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Lee H, Yeo H, Park J, Kang K, Yi SJ, Kim K. Adaptation responses to salt stress in the gut of Poecilia reticulata. Anim Cells Syst (Seoul) 2025; 29:84-99. [PMID: 39839657 PMCID: PMC11749108 DOI: 10.1080/19768354.2025.2451413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 11/29/2024] [Accepted: 12/24/2024] [Indexed: 01/23/2025] Open
Abstract
Osmoregulation is essential for the survival of aquatic organisms, particularly teleost fish facing osmotic challenges in environments characterized by variable salinity. While the gills are known for ion exchange, the intestine's role in water and salt absorption is gaining attention. Here, we investigated the adaptive responses of the intestine to salinity stress in guppies (Poecilia reticulata), observing significant morphological and transcriptomic alterations. Guppies showed superior salt tolerance compared to zebrafish (Danio rerio). Increasing salinity reduced villus length and intestinal diameter in guppies, while zebrafish exhibited damage to villus structure and loss of goblet cells. Transcriptomic analysis identified key genes involved in osmoregulation, tissue remodeling, and immune modulation. Upregulated genes included the solute carrier transporters slc2al and slc3al, which facilitate ion and water transport, as well as a transcription factor AP-1 subunit and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta, both of which participate in tissue repair and growth responses. In contrast, many genes related to the innate immune system (such as Tnfaip6) were downregulated, suggesting a shift toward the prioritization of osmoregulatory functions over immune responses. Interestingly, the differential expression of adaptation genes was linked to variations in epigenetic modifications and transcription factor activity. Transcription factors crucial for adapting to salt stress, such as bhlhe40, cebpd, and gata6, were progressively upregulated in guppies but remained downregulated in zebrafish. Our findings highlight the intricate mechanisms of adaptation to salinity stress in P. reticulata, providing insights into osmoregulatory mechanisms involving the intestine in aquatic organisms.
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Affiliation(s)
- Hyerim Lee
- Department of Biological Sciences and Biotechnology, Chungbuk National University, Cheongju, Republic of Korea
| | - Hyunjae Yeo
- Department of Biological Sciences and Biotechnology, Chungbuk National University, Cheongju, Republic of Korea
| | - Jihye Park
- Department of Microbiology, Dankook University, Cheonan, Republic of Korea
| | - Keunsoo Kang
- Department of Microbiology, Dankook University, Cheonan, Republic of Korea
| | - Sun-Ju Yi
- Department of Biological Sciences and Biotechnology, Chungbuk National University, Cheongju, Republic of Korea
| | - Kyunghwan Kim
- Department of Biological Sciences and Biotechnology, Chungbuk National University, Cheongju, Republic of Korea
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Velotta JP, Iqbal AR, Glenn ES, Franckowiak RP, Formenti G, Mountcastle J, Balacco J, Tracey A, Sims Y, Howe K, Fedrigo O, Jarvis ED, Therkildsen NO. A Complete Assembly and Annotation of the American Shad Genome Yields Insights into the Origins of Diadromy. Genome Biol Evol 2025; 17:evae276. [PMID: 39786563 PMCID: PMC11759296 DOI: 10.1093/gbe/evae276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 10/15/2024] [Accepted: 12/16/2024] [Indexed: 01/12/2025] Open
Abstract
Transitions across ecological boundaries, such as those separating freshwater from the sea, are major drivers of phenotypic innovation and biodiversity. Despite their importance to evolutionary history, we know little about the mechanisms by which such transitions are accomplished. To help shed light on these mechanisms, we generated the first high-quality, near-complete assembly and annotation of the genome of the American shad (Alosa sapidissima), an ancestrally diadromous (migratory between salinities) fish in the order Clupeiformes of major cultural and historical significance. Among the Clupeiformes, there is a large amount of variation in salinity habitat and many independent instances of salinity boundary crossing, making this taxon well-suited for studies of mechanisms underlying ecological transitions. Our initial analysis of the American shad genome reveals several unique insights for future study including: (i) that genomic repeat content is among the highest of any fish studied to date; (ii) that genome-wide heterozygosity is low and may be associated with range-wide population collapses since the 19th century; and (iii) that natural selection has acted on the branch leading to the diadromous genus Alosa. Our analysis suggests that functional targets of natural selection may include diet, particularly lipid metabolism, as well as cytoskeletal remodeling and sensing of salinity changes. Natural selection on these functions is expected in the transition from a marine to diadromous life history, particularly in the tolerance of nutrient- and ion-devoid freshwater. We anticipate that our assembly of the American shad genome will be used to test future hypotheses on adaptation to novel environments, the origins of diadromy, and adaptive variation in life history strategies, among others.
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Affiliation(s)
- Jonathan P Velotta
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| | - Azwad R Iqbal
- Department of Natural Resources and the Environment, Cornell University, Ithaca, NY 14853, USA
| | - Emma S Glenn
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
| | - Ryan P Franckowiak
- Department of Natural Resources and the Environment, Cornell University, Ithaca, NY 14853, USA
| | - Giulio Formenti
- The Vertebrate Genome Laboratory, The Rockefeller University, New York, NY 10021, USA
| | - Jacquelyn Mountcastle
- The Vertebrate Genome Laboratory, The Rockefeller University, New York, NY 10021, USA
| | - Jennifer Balacco
- The Vertebrate Genome Laboratory, The Rockefeller University, New York, NY 10021, USA
| | - Alan Tracey
- Tree of Life, Wellcome Sanger Institute, Cambridge, UK
| | - Ying Sims
- Tree of Life, Wellcome Sanger Institute, Cambridge, UK
| | - Kerstin Howe
- Tree of Life, Wellcome Sanger Institute, Cambridge, UK
| | - Olivier Fedrigo
- The Vertebrate Genome Laboratory, The Rockefeller University, New York, NY 10021, USA
| | - Erich D Jarvis
- The Vertebrate Genome Laboratory, The Rockefeller University, New York, NY 10021, USA
| | - Nina O Therkildsen
- Department of Natural Resources and the Environment, Cornell University, Ithaca, NY 14853, USA
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3
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Breves JP, Puterbaugh KM, Bradley SE, Hageman AE, Verspyck AJ, Shaw LH, Danielson EC, Hou Y. Molecular targets of prolactin in mummichogs (Fundulus heteroclitus): Ion transporters/channels, aquaporins, and claudins. Gen Comp Endocrinol 2022; 325:114051. [PMID: 35533740 DOI: 10.1016/j.ygcen.2022.114051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/25/2022] [Accepted: 05/02/2022] [Indexed: 11/30/2022]
Abstract
Prolactin (Prl) was identified over 60 years ago in mummichogs (Fundulus heteroclitus) as a "freshwater (FW)-adapting hormone", yet the cellular and molecular targets of Prl in this model teleost have remained unknown. Here, we conducted a phylogenetic analysis of two mummichog Prl receptors (Prlrs), designated Prlra and Prlrb, prior to describing the tissue- and salinity-dependent expression of their associated mRNAs. We then administered ovine Prl (oPrl) to mummichogs held in brackish water and characterized the expression of genes associated with FW- and seawater (SW)-type ionocytes. Within FW-type ionocytes, oPrl stimulated the expression of Na+/Cl- cotransporter 2 (ncc2) and aquaporin 3 (aqp3). Alternatively, branchial Na+/H+ exchanger 2 and -3 (nhe2 and -3) expression did not respond to oPrl. Gene transcripts associated with SW-type ionocytes, including Na+/K+/2Cl- cotransporter 1 (nkcc1), cystic fibrosis transmembrane regulator 1 (cftr1), and claudin 10f (cldn10f) were reduced by oPrl. Isolated gill filaments incubated with oPrl in vitro exhibited elevated ncc2 and prlra expression. Given the role of Aqps in supporting gastrointestinal fluid absorption, we assessed whether several intestinal aqp transcripts were responsive to oPrl and found that aqp1a and -8 levels were reduced by oPrl. Our collective data indicate that Prl promotes FW-acclimation in mummichogs by orchestrating the expression of solute transporters/channels, water channels, and tight-junction proteins across multiple osmoregulatory organs.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA.
| | - Katie M Puterbaugh
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Serena E Bradley
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Annie E Hageman
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Adrian J Verspyck
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Lydia H Shaw
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Elizabeth C Danielson
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Yubo Hou
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
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Velselvi R, Dasgupta S, Varghese T, Sahu NP, Tripathi G, Panmei H, Singha KP, Krishna G. Taurine and/or inorganic potassium as dietary osmolyte counter the stress and enhance the growth of GIFT reared in ion imbalanced low saline water. FOOD CHEMISTRY. MOLECULAR SCIENCES 2022; 4:100058. [PMID: 35415671 PMCID: PMC8991973 DOI: 10.1016/j.fochms.2021.100058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/13/2021] [Accepted: 11/25/2021] [Indexed: 11/06/2022]
Abstract
The effects of dietary osmolytes for alleviating osmotic stress and enhancing growth are not well elucidated in fish reared in inland saline water. The present study evaluated the effects of dietary taurine or potassium (K+) individually or in combination on growth, ionic homeostasis, and stress response of GIFT tilapia reared in potassium deficient low saline water (PDLSW, 10 ppt salinity) mimicking inland saline water. Isonitrogenous and isoenergetic diets supplemented with five potassium concentrations (0, 0.3, 0.45, 0.6 and 0.75 %), two taurine (T) concentrations (0.5 and 1.0 %) and two combinations of both (K+ 0.1 % + T 0.5 % and K+ 0.2 % + T 0.5 %) were fed to GIFT juveniles (4.4 ± 0.02 g body weight) and reared in PDLSW for 45 days. The fish fed on the diet fortifying with K+ 0.2 % + T 0.5 % showed the highest growth performance among the controls and other treatment groups. Dietary supplementation had no effects on PDLSW induced increase in osmoregulatory endpoints. The optimum dietary potassium requirement of GIFT reared in PDLSW was 0.57 and 0.599 g/100 g diet. Dietary K+ down-regulated the PDLSW induced expression of NKAa1, AQP1, and ClC2, whereas inhibited taurine-induced up-regulation of AQP1 and CLC2, which is the first report in tilapia. In addition, dietary K+ and taurine modulated antioxidant and metabolic enzyme activities for easing stress and balancing energy requirements. Thus, blending of potassium (0.2 %) and taurine (0.5 %) in the diet appears best to mitigate stress and enhance GIFT growth reared in inland saline water.
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Affiliation(s)
| | - Subrata Dasgupta
- ICAR-Central Institute of Fisheries Education, Salt Lake City, Kolkata, India
| | - Tincy Varghese
- ICAR-Central Institute of Fisheries Education, Versova, Mumbai, India
| | | | - Gayatri Tripathi
- ICAR-Central Institute of Fisheries Education, Versova, Mumbai, India
| | - Hougaina Panmei
- ICAR-Central Institute of Fisheries Education, Versova, Mumbai, India
| | | | - Gopal Krishna
- ICAR-Central Institute of Fisheries Education, Versova, Mumbai, India
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Hieu DQ, Hang BTB, Lokesh J, Garigliany MM, Huong DTT, Yen DT, Liem PT, Tam BM, Hai DM, Son VN, Phuong NT, Farnir F, Kestemont P. Salinity significantly affects intestinal microbiota and gene expression in striped catfish juveniles. Appl Microbiol Biotechnol 2022; 106:3245-3264. [PMID: 35366085 DOI: 10.1007/s00253-022-11895-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/08/2022] [Accepted: 03/19/2022] [Indexed: 12/17/2022]
Abstract
In the present study, juvenile striped catfish (Pangasianodon hypophthalmus), a freshwater fish species, have been chronically exposed to a salinity gradient from freshwater to 20 psu (practical salinity unit) and were sampled at the beginning (D20) and the end (D34) of exposure. The results revealed that the intestinal microbial profile of striped catfish reared in freshwater conditions were dominated by the phyla Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia. Alpha diversity measures (observed OTUs (operational taxonomic units), Shannon and Faith's PD (phylogenetic diversity)) showed a decreasing pattern as the salinities increased, except for the phylogenetic diversity at D34, which was showing an opposite trend. Furthermore, the beta diversity between groups was significantly different. Vibrio and Akkermansia genera were affected differentially with increasing salinity, the former being increased while the latter was decreased. The genus Sulfurospirillium was found predominantly in fish submitted to salinity treatments. Regarding the host response, the fish intestine likely contributed to osmoregulation by modifying the expression of osmoregulatory genes such as nka1a, nka1b, slc12a1, slc12a2, cftr, and aqp1, especially in fish exposed to 15 and 20 psu. The expression of heat shock proteins (hsp) hsp60, hsp70, and hsp90 was significantly increased in fish reared in 15 and 20 psu. On the other hand, the expression of pattern recognition receptors (PRRs) were inhibited in fish exposed to 20 psu at D20. In conclusion, the fish intestinal microbiota was significantly disrupted in salinities higher than 10 psu and these effects were proportional to the exposure time. In addition, the modifications of intestinal gene expression related to ion exchange and stressful responses may help the fish to adapt hyperosmotic environment. KEY POINTS: • It is the first study to provide detailed information on the gut microbiota of fish using the amplicon sequencing method. • Salinity environment significantly modified the intestinal microbiota of striped catfish. • Intestinal responses may help the fish adapt to hyperosmotic environment.
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Affiliation(s)
- Dang Quang Hieu
- Research Unit in Environmental and Evolutionary Biology, Institute of Life Earth & Environment (ILEE), University of Namur, Namur, Belgium.
| | - Bui Thi Bich Hang
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Jep Lokesh
- Université de Pau Et Des Pays de L'Adour, Saint-Pee-sur-Nivelle, E2S UPPA, INRAE, NuMéA, France
| | - Mutien-Marie Garigliany
- Department of Pathology, Faculty of Veterinary Medicine, University of Liège, Liege, Belgium
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Duong Thuy Yen
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Pham Thanh Liem
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Bui Minh Tam
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Dao Minh Hai
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam.,Department of Animal Production, Faculty of Veterinary Medicine, University of Liège, Liege, Belgium
| | - Vo Nam Son
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Frédéric Farnir
- Department of Animal Production, Faculty of Veterinary Medicine, University of Liège, Liege, Belgium
| | - Patrick Kestemont
- Research Unit in Environmental and Evolutionary Biology, Institute of Life Earth & Environment (ILEE), University of Namur, Namur, Belgium.
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6
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Syropoulou E, Benini E, Sørensen SR, Butts IAE, Tomkiewicz J, Politis SN. Early and abrupt salinity reduction impacts European eel larval culture. FISH PHYSIOLOGY AND BIOCHEMISTRY 2022; 48:355-366. [PMID: 35156136 DOI: 10.1007/s10695-022-01056-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Reducing water salinity towards iso-osmotic conditions is a common practice applied in euryhaline fish farming to limit osmoregulation costs and enhance growth. In this respect, the present study investigated the timing of salinity reduction in an abrupt manner during European eel (Anguilla anguilla) larval culture by examining associated impacts on morphological and molecular levels. Larvae from 3 different parental combinations (families) were reared at constant 36 psu for 6 days (control) or subjected to a direct reduction to 18 psu on 1, 2, or 3 days post-hatch. Overall, salinity reduction enhanced growth and survival, resulting from more efficient energy resource utilization. In the control group, expression of growth-related igf2 remained constant, demonstrating a steady growth progression, while igf1 expression increased over time only for the salinity reduced treatments, potentially qualifying as a useful biomarker for growth performance. Even though each parental combination seems to have a different capacity to cope with salinity alterations, as observed by family-driven water-transport-related aquaporin (aqp1, aqp3) gene expression, it could be inferred that the abrupt salinity change is generally not stressful, based on non-upregulated heat shock proteins (hsp70, hsp90). However, the applied salinity reduction (irrespective of timing) induced the development of pericardial edema. As such, we conclude that despite the positive effect of salinity reduction on early growth and survival, the long-term benefit for eel larval culture lies in establishing a protocol for salinity reduction, at a precise developmental time point, without causing pericardial malformations.
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Affiliation(s)
- E Syropoulou
- Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark
- Aquaculture and Fisheries Group, Wageningen University & Research, Wageningen, Netherlands
| | - E Benini
- Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark
| | - S R Sørensen
- Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark
- Billund Aquaculture A/S, Billund, Denmark
| | - I A E Butts
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, USA
| | - J Tomkiewicz
- Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark
| | - S N Politis
- Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark.
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Drechsel V, Schneebauer G, Fiechtner B, Cutler CP, Pelster B. Aquaporin expression and cholesterol content in eel swimbladder tissue. JOURNAL OF FISH BIOLOGY 2022; 100:609-618. [PMID: 34882794 PMCID: PMC9302985 DOI: 10.1111/jfb.14973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 05/08/2023]
Abstract
Leakiness of the swimbladder wall of teleost fishes must be prevented to avoid diffusional loss of gases out of the swimbladder. Guanine incrustation as well as high concentrations of cholesterol in swimbladder membranes in midwater and deep-sea fish has been connected to a reduced gas permeability of the swimbladder wall. On the contrary, the swimbladder is filled by diffusion of gases, mainly oxygen and CO2 , from the blood and the gas gland cells into the swimbladder lumen. In swimbladder tissue of the zebrafish and the Japanese eel, aquaporin mRNA has been detected, and the aquaporin protein has been considered important for the diffusion of water, which may accidentally be gulped by physostome fish when taking an air breath. In the present study, the expression of two aquaporin 1 genes (Aqp1aa and Aqp1ab) in the swimbladder tissue of the European eel, a functional physoclist fish, was assessed using immunohistochemistry, and the expression of both genes was detected in endothelial cells of swimbladder capillaries as well as in basolateral membranes of gas gland cells. In addition, Aqp1ab was present in apical membranes of swimbladder gas gland cells. The authors also found high concentrations of cholesterol in these membranes, which were several fold higher than in muscle tissue membranes. In yellow eels the cholesterol concentration exceeded the concentration detected in silver eel swimbladder membranes. The authors suggest that aquaporin 1 in swimbladder gas gland cells and endothelial cells facilitates CO2 diffusion into the blood, enhancing the switch-on of the Root effect, which is essential for the secretion of oxygen into the swimbladder. It may also facilitate CO2 diffusion into the swimbladder lumen along the partial gradient established by CO2 production in gas gland cells. Cholesterol has been shown to reduce the gas permeability of membranes and thus could contribute to the gas tightness of swimbladder membranes, which is essential to avoid diffusional loss of gas out of the swimbladder.
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Affiliation(s)
- Victoria Drechsel
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Gabriel Schneebauer
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Birgit Fiechtner
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | | | - Bernd Pelster
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
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Cloning and Expression of Four Aquaporin Homologs from the Chinese Black Sleeper (Bostrychus sinensis): The Effects of Salinity Acclimation. Biochem Genet 2021; 59:837-855. [PMID: 33544299 DOI: 10.1007/s10528-021-10033-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
Several fish species are known to possess mechanisms that allow them to adapt to environments with different salinities. The aim of this study was to investigate the effects of salinity on the expression of aquaporins (aqp1a, aqp3a, aqp8a, and aqp9a) in the gills and intestines of Chinese black sleeper. After 30 days of acclimation, the expression of aqp1a, aqp3a, and aqp9a in the gills was significantly higher in fish transferred to 5 ppt than in those transferred to 40 ppt seawater, whereas aqp8 expression was lower. In contrast, aqp1a, aqp3a, and aqp8a expression in the intestines was higher in fish acclimated in 40 ppt than in those acclimated in 5 ppt. During abrupt salinity acclimation, the levels of aqp1a and aqp9a in the gills varied over time in fish acclimated in 5 ppt, but not in 40 ppt. The aqp3a levels in gills were higher in the 5 ppt group after 24 h than in the 40 ppt. The expression level of aqp8a in gills was higher in 40 ppt than in 5 ppt, except for that at 12 h. In the intestines, expression level of aqp1a and aqp8a were significantly upregulated from 12 to 48 h following acclimation in 40 ppt and aqp3a was higher in 40 ppt group than in 5 ppt, while aqp9a expression exhibited an opposite trend. These findings suggest that aqp1a, aqp3a, aqp8a and aqp9a may play a major osmoregulatory role in water transport in the gills and intestines during acclimation to different salinity environment.
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9
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Breves JP, Popp EE, Rothenberg EF, Rosenstein CW, Maffett KM, Guertin RR. Osmoregulatory actions of prolactin in the gastrointestinal tract of fishes. Gen Comp Endocrinol 2020; 298:113589. [PMID: 32827513 DOI: 10.1016/j.ygcen.2020.113589] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/17/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023]
Abstract
In fishes, prolactin (Prl) signaling underlies the homeostatic regulation of hydromineral balance by controlling essential solute and water transporting functions performed by the gill, gastrointestinal tract, kidney, urinary bladder, and integument. Comparative studies spanning over 60 years have firmly established that Prl promotes physiological activities that enable euryhaline and stenohaline teleosts to reside in freshwater environments; nonetheless, the specific molecular and cellular targets of Prl in ion- and water-transporting tissues are still being resolved. In this short review, we discuss how particular targets of Prl (e.g., ion cotransporters, tight-junction proteins, and ion pumps) confer adaptive functions to the esophagus and intestine. Additionally, in some instances, Prl promotes histological and functional transformations within esophageal and intestinal epithelia by regulating cell proliferation. Collectively, the demonstrated actions of Prl in the gastrointestinal tract of teleosts indicate that Prl operates to promote phenotypes supportive of freshwater acclimation and to inhibit phenotypes associated with seawater acclimation. We conclude our review by underscoring that future investigations are warranted to determine how growth hormone/Prl-family signaling evolved in basal fishes to support the gastrointestinal processes underlying hydromineral balance.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA.
| | - Emily E Popp
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Eva F Rothenberg
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Clarence W Rosenstein
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Kaitlyn M Maffett
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
| | - Rebecca R Guertin
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866, USA
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10
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Abstract
Shifts between habitats during reproduction can induce costs that are independent of the reproductive effort and that often apply to both sexes. Such shifts can also illustrate physiological costs complementary to those involving energetic currencies. In this study, we investigated osmotic consequences of reproduction in a context where reproduction induces a shift from terrestrial habitats to freshwater environments. During reproduction, toads migrate to breeding ponds where males remain for several weeks, while females leave shortly after egg-laying. We assessed plasma osmolality of male spined toads during the whole reproductive period (approx. 30 days) in conjunction with markers of individual condition. We found that osmolality decreases during the protracted period of immersion in freshwater during reproduction, presumably through water influx as indicated by body mass changes. Hormonal markers of metabolism and sexual activity were positively correlated with osmolality. Recent research has highlighted hydric 'costs' of reproduction when access to water is limited. Our study adds to this growing field of investigation, yet with an opposite perspective, where water availability linked to reproduction provokes hyperhydration rather than dehydration.
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Affiliation(s)
- François Brischoux
- Centre d'Etudes Biologiques de Chizé, CEBC UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
| | - Marion Cheron
- Centre d'Etudes Biologiques de Chizé, CEBC UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
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11
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Lorente-Martínez H, Agorreta A, Torres-Sánchez M, San Mauro D. Evidence of positive selection suggests possible role of aquaporins in the water-to-land transition of mudskippers. ORG DIVERS EVOL 2018. [DOI: 10.1007/s13127-018-0382-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Politis SN, Mazurais D, Servili A, Zambonino-Infante JL, Miest JJ, Tomkiewicz J, Butts IAE. Salinity reduction benefits European eel larvae: Insights at the morphological and molecular level. PLoS One 2018; 13:e0198294. [PMID: 29897966 PMCID: PMC5999099 DOI: 10.1371/journal.pone.0198294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/16/2018] [Indexed: 11/23/2022] Open
Abstract
European eel (Anguilla anguilla) is a euryhaline species, that has adapted to cope with both, hyper- and hypo-osmotic environments. This study investigates the effect of salinity, from a morphological and molecular point of view on European eel larvae reared from 0 to 12 days post hatch (dph). Offspring reared in 36 practical salinity units (psu; control), were compared with larvae reared in six scenarios, where salinity was decreased on 0 or 3 dph and in rates of 1, 2 or 4 psu/day, towards iso-osmotic conditions. Results showed that several genes relating to osmoregulation (nkcc2α, nkcc2β, aqp1dup, aqpe), stress response (hsp70, hsp90), and thyroid metabolism (thrαA, thrαB, thrβB, dio1, dio2, dio3) were differentially expressed throughout larval development, while nkcc1α, nkcc2β, aqp3, aqp1dup, aqpe, hsp90, thrαA and dio3 showed lower expression in response to the salinity reduction. Moreover, larvae were able to keep energy metabolism related gene expression (atp6, cox1) at stable levels, irrespective of the salinity reduction. As such, when reducing salinity, an energy surplus associated to reduced osmoregulation demands and stress (lower nkcc, aqp and hsp expression), likely facilitated the observed increased survival, improved biometry and enhanced growth efficiency. Additionally, the salinity reduction decreased the amount of severe deformities such as spinal curvature and emaciation but also induced an edematous state of the larval heart, resulting in the most balanced mortality/deformity ratio when salinity was decreased on 3 dph and at 2 psu/day. However, the persistency of the pericardial edema and if or how it represents an obstacle in further larval development needs to be further clarified. In conclusion, this study clearly showed that salinity reduction regimes towards iso-osmotic conditions facilitated the European eel pre-leptocephalus development and revealed the existence of highly sensitive and regulated osmoregulation processes at such early life stage of this species.
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Affiliation(s)
- Sebastian N. Politis
- National Institute of Aquatic Resources, Technical University of Denmark, DTU, Lyngby, Denmark
- * E-mail:
| | - David Mazurais
- Ifremer, Marine Environmental Science Laboratory UMR 6539, Plouzané, France
| | - Arianna Servili
- Ifremer, Marine Environmental Science Laboratory UMR 6539, Plouzané, France
| | | | | | - Jonna Tomkiewicz
- National Institute of Aquatic Resources, Technical University of Denmark, DTU, Lyngby, Denmark
| | - Ian A. E. Butts
- National Institute of Aquatic Resources, Technical University of Denmark, DTU, Lyngby, Denmark
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Cao Q, Gu J, Wang D, Liang F, Zhang H, Li X, Yin S. Physiological mechanism of osmoregulatory adaptation in anguillid eels. FISH PHYSIOLOGY AND BIOCHEMISTRY 2018; 44:423-433. [PMID: 29344774 PMCID: PMC5862950 DOI: 10.1007/s10695-018-0464-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 01/03/2018] [Indexed: 06/07/2023]
Abstract
In recent years, the production of eel larvae has dramatic declines due to reductions in spawning stocks, overfishing, growth habitat destruction and access reductions, and pollution. Therefore, it is particularly important and urgent for artificial production of glass eels. However, the technique of artificial hatching and rearing larvae is still immature, which has long been regarded as an extremely difficult task. One of the huge gaps is artificial condition which is far from the natural condition to develop their capability of osmoregulation. Thus, understanding their osmoregulatory mechanisms will help to improve the breed and adapt to the changes in the environment. In this paper, we give a general review for a study progress of osmoregulatory mechanisms in eels from five aspects including tissues and organs, ion transporters, hormones, proteins, and high throughput sequencing methods.
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Affiliation(s)
- Quanquan Cao
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China
| | - Jie Gu
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Dan Wang
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China
| | - Fenfei Liang
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China
| | - Hongye Zhang
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China
| | - Xinru Li
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China
| | - Shaowu Yin
- College of Life Sciences, Key Laboratory of Biodiversity and Biotechnology of Jiangsu Province, Nanjing Normal University, 1 Wenyuan Road, Nanjing, Jiangsu Province, 210023, China.
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14
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Robertson LS, Galbraith HS, Iwanowicz D, Blakeslee CJ, Cornman RS. RNA sequencing analysis of transcriptional change in the freshwater mussel Elliptio complanata after environmentally relevant sodium chloride exposure. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:2352-2366. [PMID: 28224655 DOI: 10.1002/etc.3774] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 10/25/2016] [Accepted: 02/17/2017] [Indexed: 06/06/2023]
Abstract
To identify potential biomarkers of salt stress in a freshwater sentinel species, we examined transcriptional responses of the common mussel Elliptio complanata to controlled sodium chloride (NaCl) exposures. Ribonucleic acid sequencing (RNA-Seq) of mantle tissue identified 481 transcripts differentially expressed in adult mussels exposed to 2 ppt NaCl (1.2 ppt chloride) for 7 d, of which 290 had nonoverlapping intervals. Differentially expressed gene categories included ion and transmembrane transport, oxidoreductase activity, maintenance of protein folding, and amino acid metabolism. The rate-limiting enzyme for synthesis of taurine, an amino acid frequently linked to osmotic stress in aquatic species, was upregulated, as was the transmembrane ion pump sodium/potassium adenosine 5'-triphosphatase. These patterns confirm a primary transcriptional response to the experimental dose, albeit likely overlapping with nonspecific secondary stress responses. Substantial involvement of the heat shock protein 70 chaperone family and the water-transporting aquaporin family was not detected, however, in contrast to some studies in other bivalves. A subset of the most significantly regulated genes was confirmed by quantitative polymerase chain reaction in an independent sample. Cluster analysis showed separation of mussels exposed to 2 ppt NaCl from control mussels in multivariate space, but mussels exposed to 1 ppt NaCl were largely indistinguishable from controls. Transcriptome-scale analysis of salt exposure under laboratory conditions efficiently identified candidate biomarkers for further functional analysis and field validation. Environ Toxicol Chem 2017;36:2352-2366. © Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
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Affiliation(s)
- Laura S Robertson
- Leetown Science Center, US Geological Survey, Kearneysville, West Virginia
| | - Heather S Galbraith
- Northern Appalachian Research Laboratory, Leetown Science Center, US Geological Survey, Wellsboro, Pennsylvania
| | - Deborah Iwanowicz
- Leetown Science Center, US Geological Survey, Kearneysville, West Virginia
| | - Carrie J Blakeslee
- Northern Appalachian Research Laboratory, Leetown Science Center, US Geological Survey, Wellsboro, Pennsylvania
| | - R Scott Cornman
- Fort Collins Science Center, US Geological Survey, Fort Collins, Colorado
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15
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Kalujnaia S, Hazon N, Cramb G. Myo-inositol phosphate synthase expression in the European eel (Anguilla anguilla) and Nile tilapia (Oreochromis niloticus): effect of seawater acclimation. Am J Physiol Regul Integr Comp Physiol 2016; 311:R287-98. [PMID: 27252471 PMCID: PMC5008666 DOI: 10.1152/ajpregu.00056.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 05/25/2016] [Indexed: 11/29/2022]
Abstract
A single MIPS gene (Isyna1/Ino1) exists in eel and tilapia genomes with a single myo-d-inositol 3-phosphate synthase (MIPS) transcript identified in all eel tissues, although two MIPS spliced variants [termed MIPS(s) and MIPS(l)] are found in all tilapia tissues. The larger tilapia transcript [MIPS(l)] results from the inclusion of the 87-nucleotide intron between exons 5 and 6 in the genomic sequence. In most tilapia tissues, the MIPS(s) transcript exhibits much higher abundance (generally >10-fold) with the exception of white skeletal muscle and oocytes, in which the MIPS(l) transcript predominates. SW acclimation resulted in large (6- to 32-fold) increases in mRNA expression for both MIPS(s) and MIPS(l) in all tilapia tissues tested, whereas in the eel, changes in expression were limited to a more modest 2.5-fold increase and only in the kidney. Western blots identified a number of species- and tissue-specific immunoreactive MIPS proteins ranging from 40 to 67 kDa molecular weight. SW acclimation failed to affect the abundance of any immunoreactive protein in any tissue tested from the eel. However, a major 67-kDa immunoreactive protein (presumed to be MIPS) found in tilapia tissues exhibited 11- and 54-fold increases in expression in gill and fin samples from SW-acclimated fish. Immunohistochemical investigations revealed specific immunoreactivity in the gill, fin, skin, and intestine taken from only SW-acclimated tilapia. Immunofluorescence indicated that MIPS was expressed within gill chondrocytes and epithelial cells of the primary filaments, basal epithelial cell layers of the skin and fin, the cytosol of columnar intestinal epithelial and mucous cells, as well as unknown entero-endocrine-like cells.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom; and
| | - Neil Hazon
- School of Biology, University of St. Andrews, St. Andrews, United Kingdom
| | - Gordon Cramb
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom; and
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16
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Madsen SS, Engelund MB, Cutler CP. Water transport and functional dynamics of aquaporins in osmoregulatory organs of fishes. THE BIOLOGICAL BULLETIN 2015; 229:70-92. [PMID: 26338871 DOI: 10.1086/bblv229n1p70] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Aquaporins play distinct roles for water transport in fishes as they do in mammals-both at the cellular, organ, and organismal levels. However, with over 32,000 known species of fishes inhabiting almost every aquatic environment, from tidal pools, small mountain streams, to the oceans and extreme salty desert lakes, the challenge to obtain consensus as well as specific knowledge about aquaporin physiology in these vertebrate clades is overwhelming. Because the integumental surfaces of these animals are in intimate contact with the surrounding milieu, passive water loss and uptake represent two of the major osmoregulatory challenges that need compensation. However, neither obligatory nor regulatory water transport nor their mechanisms have been elucidated to the same degree as, for example, ion transport in fishes. Currently fewer than 60 papers address fish aquaporins. Most of these papers identify "what is present" and describe tissue expression patterns in various teleosts. The agnathans, chondrichthyans, and functionality of fish aquaporins generally have received little attention. This review emphasizes the functional physiology of aquaporins in fishes, focusing on transepithelial water transport in osmoregulatory organs in euryhaline species - primarily teleosts, but covering other taxonomic groups as well. Most current knowledge comes from teleosts, and there is a strong need for related information on older fish clades. Our survey aims to stimulate new, original research in this area and to bring together new collaborations across disciplines.
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Affiliation(s)
- Steffen S Madsen
- Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark;
| | - Morten B Engelund
- Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Christopher P Cutler
- Department of Biology, Georgia Southern University, P.O. Box 8042, Statesboro, Georgia 30460
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17
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Carvalho ESM, Gregório SF, Canário AVM, Power DM, Fuentes J. PTHrP regulates water absorption and aquaporin expression in the intestine of the marine sea bream (Sparus aurata, L.). Gen Comp Endocrinol 2015; 213:24-31. [PMID: 25562629 DOI: 10.1016/j.ygcen.2014.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/25/2014] [Accepted: 12/27/2014] [Indexed: 11/22/2022]
Abstract
Water ingestion by drinking is fundamental for ion homeostasis in marine fish. However, the fluid ingested requires processing to allow net water absorption in the intestine. The formation of luminal carbonate aggregates impacts on calcium homeostasis and requires epithelial HCO3(-) secretion to enable water absorption. In light of its endocrine importance in calcium handling and the indication of involvement in HCO3(-) secretion the present study was designed to expose the role of the parathyroid hormone-related protein (PTHrP) in HCO3(-) secretion, water absorption and the regulation of aqp1 gene expression in the anterior intestine of the sea bream. HCO3(-) secretion rapidly decreased when PTHrP(1-34) was added to anterior intestine of the sea bream mounted in Ussing chambers. The effect achieved a maximum inhibition of 60% of basal secretion rates, showing a threshold effective dose of 0.1 ng ml(-1) compatible with reported plasma values of PTHrP. When applied in combination with the adenylate cyclase inhibitor (SQ 22.536, 100 μmol l(-1)) or the phospholipase C inhibitor (U73122, 10 μmol l(-1)) the effect of PTHrP(1-34) on HCO3(-) secretion was reduced by about 50% in both cases. In parallel, bulk water absorption measured in intestinal sacs was sensitive to inhibition by PTHrP. The inhibitory action conforms to a typical dose-response curve in the range of 0.1-1000 ng ml(-1), achieves a maximal effect of 60-65% inhibition from basal rates and shows threshold significant effects at hormone levels of 0.1 ng ml(-1). The action of PTHrP in water absorption was completely abolished in the presence of the adenylate cyclase inhibitor (SQ 22.536, 100 μmol l(-1)) and was insensitive to the phospholipase C inhibitor (U73122, 10 μmol l(-1)). In vivo injections of PTHrP(1-34) or the PTH/PTHrP receptor antagonist PTHrP(7-34) evoked respectively, a significant decrease or increase of aqp1ab, but not aqp1a. Overall the present results suggest that PTHrP acts as a key regulator of carbonate aggregate formation in the intestine of marine fish via its actions on water absorption, calcium regulation and HCO3(-) secretion.
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Affiliation(s)
- Edison S M Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Sílvia F Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Adelino V M Canário
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Deborah M Power
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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18
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Wong MKS, Ozaki H, Suzuki Y, Iwasaki W, Takei Y. Discovery of osmotic sensitive transcription factors in fish intestine via a transcriptomic approach. BMC Genomics 2014; 15:1134. [PMID: 25520040 PMCID: PMC4377849 DOI: 10.1186/1471-2164-15-1134] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 12/09/2014] [Indexed: 11/10/2022] Open
Abstract
Background Teleost intestine is crucial for seawater acclimation by sensing osmolality of imbibed seawater and regulating drinking and water/ion absorption. Regulatory genes for transforming intestinal function have not been identified. A transcriptomic approach was used to search for such genes in the intestine of euryhaline medaka. Results Quantitative RNA-seq by Illumina Hi-Seq Sequencing method was performed to analyze intestinal gene expression 0 h, 1 h, 3 h, 1 d, and 7 d after seawater transfer. Gene ontology (GO) enrichment results showed that cell adhesion, signal transduction, and protein phosphorylation gene categories were augmented soon after transfer, indicating a rapid reorganization of cellular components and functions. Among >50 transiently up-regulated transcription factors selected via co-expression correlation and GO selection, five transcription factors, including CEBPB and CEBPD, were confirmed by quantitative PCR to be specific to hyperosmotic stress, while others were also up-regulated after freshwater control transfer, including some well-known osmotic-stress transcription factors such as SGK1 and TSC22D3/Ostf1. Protein interaction networks suggest a high degree of overlapping among the signaling of transcription factors that respond to osmotic and general stresses, which sheds light on the interpretation of their roles during hyperosmotic stress and emergency. Conclusions Since cortisol is an important hormone for seawater acclimation as well as for general stress in teleosts, emergency and osmotic challenges could have been evolved in parallel and resulted in the overlapped signaling networks. Our results revealed important interactions among transcription factors and offer a multifactorial perspective of genes involved in seawater acclimation. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1134) contains supplementary material, which is available to authorized users.
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19
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Ando M, Wong MKS, Takei Y. Mechanisms of guanylin action on water and ion absorption at different regions of seawater eel intestine. Am J Physiol Regul Integr Comp Physiol 2014; 307:R653-63. [PMID: 24990857 DOI: 10.1152/ajpregu.00543.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Guanylin (GN) inhibited water absorption and short-circuit current (Isc) in seawater eel intestine. Similar inhibition was observed after bumetanide, and the effect of bumetanide was abolished by GN or vice versa, suggesting that both act on the same target, Na(+)-K(+)-2Cl(-) cotransporter (NKCC), which is a key player for the Na(+)-K(+)-Cl(-) transport system responsible for water absorption in marine teleost intestine. However, effect of GN was always greater than that of bumetanide: 10% greater in middle intestine (MI) and 40% in posterior intestine (PI) for Isc, and 25% greater in MI and 34% in PI for water absorption. After treatment with GN, Isc decreased to zero, but 20-30% water absorption still remained. The remainder may be due to the Cl(-)/HCO3 (-) exchanger and Na(+)-Cl(-) cotransporter (NCC), since inhibitors for these transporters almost nullified the remaining water absorption. Quantitative PCR analysis revealed the presence of major proteins involved in water absorption; the NKCC2β and AQP1 genes whose expression was markedly upregulated after seawater acclimation. The SLC26A6 (anion exchanger) and NCCβ genes were also expressed in small amounts. Consistent with the inhibitors' effect, expression of NKCC2β was MI > PI, and that of NCCβ was MI << PI. The present study showed that GN not only inhibits the bumetanide-sensitive Na(+)-K(+)-Cl(-) transport system governed by NKCC2β, but also regulates unknown ion transporters different from GN-insensitive SLC26A6 and NCC. A candidate is cystic fibrosis transmembrane conductance regulator Cl(-) channel, as demonstrated in mammals, but its expression is low in eel intestine, and its role may be minor, as indicated by the small effect of its inhibitors.
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Affiliation(s)
- Masaaki Ando
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Marty K S Wong
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Yoshio Takei
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
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Larsen EH, Deaton LE, Onken H, O'Donnell M, Grosell M, Dantzler WH, Weihrauch D. Osmoregulation and Excretion. Compr Physiol 2014; 4:405-573. [DOI: 10.1002/cphy.c130004] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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21
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Jeong SY, Kim JH, Lee WO, Dahms HU, Han KN. Salinity changes in the anadromous river pufferfish, Takifugu obscurus, mediate gene regulation. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:205-219. [PMID: 23907526 DOI: 10.1007/s10695-013-9837-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 07/24/2013] [Indexed: 06/02/2023]
Abstract
This study aimed to better understand the hydromineral regulatory response of the anadromous river pufferfish, Takifugu obscurus, to salinity changes through real-time RT-PCR. After abrupt transfer from 30 or 5 psu to 5 or 30 psu, respectively, we analyzed the mRNA expression of Na⁺/K⁺ ATPase, prolactin receptor, and aquaporin from osmoregulatory organs of the river pufferfish such as gills, kidney, and intestine. Na⁺/K⁺ ATPase showed notable changes in the gills and kidney when salinity was increased. In the gills, the expression level of Na⁺/K⁺ ATPase suddenly increased within a day after abrupt transfer from 5 to 30 psu and then slightly declined within 2 days after exposure. In the kidney, Na⁺/K⁺ ATPase has shown consistently high mRNA expression after the increase in salinity. Expression levels of the prolactin receptor gene increased when environmental salinity decreased. In the intestine, gene expression of the prolactin receptor remained high, even when salinity decreased. To the contrary, there was a steady increase or decrease in mRNA expression in the kidney in response to salinity decrease or increase, respectively. As for aquaporins, aquaporin 1 was mainly expressed in the intestine and kidney, and aquaporin 3 was mainly expressed in the gills and intestine. In the gills, increased expression of aquaporin 3 was found after transfer to lower salinity and in the intestine and kidney, a decrease in salinity followed by an abrupt decrease in aquaporin 1 and aquaporin 3. Contrastingly, the expression of these genes increased in the intestine after transfer to 30 psu. Osmoregulatory genes were expressed in diverse organs, apparently to overcome an influx or exhaust of water or ions. A superior adaptation ability of the river pufferfish to a wide range of salinities is most reasonably due to active osmoregulatory processes mediated by the genes monitored here.
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Affiliation(s)
- Su-Young Jeong
- Department of Marine Science, College of Natural Sciences, Inha University, Incheon, 402-751, South Korea
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22
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Kwong RWM, Kumai Y, Perry SF. The role of aquaporin and tight junction proteins in the regulation of water movement in larval zebrafish (Danio rerio). PLoS One 2013; 8:e70764. [PMID: 23967101 PMCID: PMC3743848 DOI: 10.1371/journal.pone.0070764] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 06/23/2013] [Indexed: 01/17/2023] Open
Abstract
Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafish (Danio rerio). We observed that the half-time for saturation of water influx (Ku) was 4.3±0.9 min, and reached equilibrium at approximately 30 min. These findings suggest a high turnover rate of water between the fish and the environment. Water influx was reduced by the putative AQP inhibitor phloretin (100 or 500 μM). Immunohistochemistry and confocal microscopy revealed that AQP1a1 protein was expressed in cells on the yolk sac epithelium. A substantial number of these AQP1a1-positive cells were identified as ionocytes, either H+-ATPase-rich cells or Na+/K+-ATPase-rich cells. AQP1a1 appeared to be expressed predominantly on the basolateral membranes of ionocytes, suggesting its potential involvement in regulating ionocyte volume and/or water flux into the circulation. Additionally, translational gene knockdown of AQP1a1 protein reduced water influx by approximately 30%, further indicating a role for AQP1a1 in facilitating transcellular water uptake. On the other hand, incubation with the Ca2+-chelator EDTA or knockdown of the epithelial tight junction protein claudin-b significantly increased water influx. These findings indicate that the epithelial tight junctions normally act to restrict paracellular water influx. Together, the results of the present study provide direct in vivo evidence that water movement can occur through transcellular routes (via AQP); the paracellular routes may become significant when the paracellular permeability is increased.
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Affiliation(s)
- Raymond W M Kwong
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
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Kalujnaia S, Gellatly SA, Hazon N, Villasenor A, Yancey PH, Cramb G. Seawater acclimation and inositol monophosphatase isoform expression in the European eel (Anguilla anguilla) and Nile tilapia (Orechromis niloticus). Am J Physiol Regul Integr Comp Physiol 2013; 305:R369-84. [PMID: 23739342 DOI: 10.1152/ajpregu.00044.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inositol monophosphatase (IMPA) is responsible for the synthesis of inositol, a polyol that can function as an intracellular osmolyte helping re-establish cell volume when exposed to hypertonic environments. Some epithelial tissues in euryhaline teleosts such as the eel and tilapia encounter considerable hyperosmotic challenge when fish move from freshwater (FW) to seawater (SW) environments; however, the roles played by organic osmolytes, such as inositol, have yet to be determined. Syntenic analysis has indicated that, as a result of whole genome- and tandem-duplication events, up to six IMPA isoforms can exist within teleost genomes. Four isoforms are homologs of the mammalian IMPA1 gene, and two isoforms are homologs of the mammalian IMPA2 gene. Although the tissue-dependent isoform expression profiles of the teleost isoforms appear to be species-specific, it was primarily mRNA for the IMPA1.1 isoform that was upregulated in epithelial tissues after fish were transferred to SW (up to 16-fold in eel and 90-fold in tilapia). Although up-regulation of IMPA1.1 expression was evident in many tissues in the eel, more substantial increases in IMPA1.1 expression were found in tilapia tissues, where SW acclimation resulted in up to 2,000-fold increases in protein expression, 16-fold increases in enzyme activity and 15-fold increases in tissue inositol contents. Immunohistochemical studies indicated that the tissue and cellular distribution of IMPA1.1 protein differed slightly between eels and tilapia; however, in both species the basal epithelial cell layers within the skin and fin, and the branchial epithelium and interstitial cells within the kidney, exhibited high levels of IMPA1.1 protein expression.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
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24
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Ip YK, Soh MML, Chen XL, Ong JLY, Chng YR, Ching B, Wong WP, Lam SH, Chew SF. Molecular characterization of branchial aquaporin 1aa and effects of seawater acclimation, emersion or ammonia exposure on its mRNA expression in the gills, gut, kidney and skin of the freshwater climbing perch, Anabas testudineus. PLoS One 2013; 8:e61163. [PMID: 23593418 PMCID: PMC3621907 DOI: 10.1371/journal.pone.0061163] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 03/06/2013] [Indexed: 12/27/2022] Open
Abstract
We obtained a full cDNA coding sequence of aquaporin 1aa (aqp1aa) from the gills of the freshwater climbing perch, Anabas testudineus, which had the highest expression in the gills and skin, suggesting an important role of Aqp1aa in these organs. Since seawater acclimation had no significant effects on the branchial and intestinal aqp1aa mRNA expression, and since the mRNA expression of aqp1aa in the gut was extremely low, it can be deduced that Aqp1aa, despite being a water channel, did not play a significant osmoregulatory role in A. testudineus. However, terrestrial exposure led to significant increases in the mRNA expression of aqp1aa in the gills and skin of A. testudineus. Since terrestrial exposure would lead to evaporative water loss, these results further support the proposition that Aqp1aa did not function predominantly for the permeation of water through the gills and skin. Rather, increased aqp1aa mRNA expression might be necessary to facilitate increased ammonia excretion during emersion, because A. testudineus is known to utilize amino acids as energy sources for locomotor activity with increased ammonia production on land. Furthermore, ammonia exposure resulted in significant decreases in mRNA expression of aqp1aa in the gills and skin of A. testudineus, presumably to reduce ammonia influx during ammonia loading. This corroborates previous reports on AQP1 being able to facilitate ammonia permeation. However, a molecular characterization of Aqp1aa from A. testudineus revealed that its intrinsic aquapore might not facilitate NH3 transport. Hence, ammonia probably permeated the central fifth pore of the Aqp1aa tetramer as suggested previously. Taken together, our results indicate that Aqp1aa might have a greater physiological role in ammonia excretion than in osmoregulation in A. testudineus.
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Affiliation(s)
- Yuen K Ip
- Department of Biological Science, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore.
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Chung JS, Maurer L, Bratcher M, Pitula JS, Ogburn MB. Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity. AQUATIC BIOSYSTEMS 2012; 8:21. [PMID: 22943628 PMCID: PMC3489796 DOI: 10.1186/2046-9063-8-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 07/25/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. RESULTS A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5' and 3' RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. CONCLUSIONS We report the ontogenetic variation in CasAQP-1 expression during the larval development of C. sapidus and the induction of its expression at early larval stages in the exposure of hyposalinity. However, it remains to be determined if the increase in CasAQP-1 expression at later larval stages may have a role in adaptation to hyposalinity.
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Affiliation(s)
- J Sook Chung
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 East Pratt Street, Columbus Center, Suite 236, Baltimore, MD, USA
| | - Leah Maurer
- Department of Environmental Science, University of Maryland Baltimore County, Baltimore, MD, USA
| | - Meagan Bratcher
- Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA
| | - Joseph S Pitula
- Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA
| | - Matthew B Ogburn
- Department of Natural Sciences, Savannah State University, Savannah, GA, USA
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Carvalho ESM, Gregório SF, Power DM, Canário AVM, Fuentes J. Water absorption and bicarbonate secretion in the intestine of the sea bream are regulated by transmembrane and soluble adenylyl cyclase stimulation. J Comp Physiol B 2012; 182:1069-80. [PMID: 22752677 DOI: 10.1007/s00360-012-0685-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 06/04/2012] [Accepted: 06/09/2012] [Indexed: 10/28/2022]
Abstract
In the marine fish intestine luminal, HCO₃⁻ can remove divalent ions (calcium and magnesium) by precipitation in the form of carbonate aggregates. The process of epithelial HCO₃⁻ secretion is under endocrine control, therefore, in this study we aimed to characterize the involvement of transmembrane (tmACs) and soluble (sACs) adenylyl cyclases on the regulation of bicarbonate secretion (BCS) and water absorption in the intestine of the sea bream (Sparus aurata). We observed that all sections of sea bream intestine are able to secrete bicarbonate as measured by pH-Stat in Ussing chambers. In addition, gut sac preparations reveal net water absorption in all segments of the intestine, with significantly higher absorption rates in the anterior intestine that in the rectum. BCS and water absorption are positively correlated in all regions of the sea bream intestinal tract. Furthermore, stimulation of tmACs (10 μM FK + 500 μM IBMX) causes a significant decrease in BCS, bulk water absorption and short circuit current (Isc) in a region dependent manner. In turn, stimulation of sACs with elevated HCO₃⁻ results in a significant increase in BCS, and bulk water absorption in the anterior intestine, an action completely reversed by the sAC inhibitor KH7 (200 μM). Overall, the results reveal a functional relationship between BCS and water absorption in marine fish intestine and modulation by tmACs and sAC. In light of the present observations, it is hypothesized that the endocrine effects on intestinal BCS and water absorption mediated by tmACs are locally and reciprocally modulated by the action of sACs in the fish enterocyte, thus fine-tuning the process of carbonate aggregate production in the intestinal lumen.
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Affiliation(s)
- Edison S M Carvalho
- Centre of Marine Sciences (CCMar), CIMAR-Laboratório Associado, Universidade do Algarve, Faro, Portugal
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Wood CM, Grosell M. Independence of net water flux from paracellular permeability in the intestine of Fundulus heteroclitus, a euryhaline teleost. ACTA ACUST UNITED AC 2012; 215:508-17. [PMID: 22246259 DOI: 10.1242/jeb.060004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Paracellular permeability and absorptive water flux across the intestine of the euryhaline killifish were investigated using in vitro gut sac preparations from seawater- and freshwater-acclimated animals. The permeability of polyethylene glycol (PEG), a well-established paracellular probe, was measured using trace amounts of radiolabelled oligomers of three different molecular sizes (PEG-400, PEG-900 and PEG-4000) at various times after satiation feeding. All three PEG molecules were absorbed, with permeability declining as a linear function of increasing hydrodynamic radius. Response patterns were similar in seawater and freshwater preparations, though water absorption and PEG-900 permeability were greater in the latter. Despite up to 4-fold variations in absorptive water flux associated with feeding and fasting (highest at 1-3 h, lowest at 12-24 h and intermediate at 1-2 weeks post-feeding), there were no changes in PEG permeability for any size oligomer. When PEG permeability was measured in the opposite direction (i.e. serosal to mucosal) from net water flux, it was again unchanged. HgCl(2) (10(-3) mol l(-1)), a putative blocker of aquaporins, eliminated absorptive water flux yet increased PEG-4000 permeability by 6- to 8-fold in both freshwater and seawater preparations. Experimentally raising the serosal osmolality by addition of 300 mmol l(-1) mannitol increased the absorptive water flux rate 10-fold, but did not alter PEG permeability. Under these conditions, HgCl(2) reduced absorptive water flux by 60% and again increased PEG permeability by 6- to 8-fold in both freshwater and seawater preparations. Clearly, there was no influence of solvent drag on PEG movement. The putative paracellular blocker 2,4,6-triaminopyrimidine (TAP, 20 mmol l(-1)) had no effect on net water flux or PEG permeability. We conclude that PEG and water move by separate pathways; absorptive water transport probably occurs via a transcellular route in the intestine of Fundulus heteroclitus.
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Affiliation(s)
- Chris M Wood
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149, USA.
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Chauvigné F, Zapater C, Cerdà J. Role of Aquaporins during Teleost Gametogenesis and Early Embryogenesis. Front Physiol 2011; 2:66. [PMID: 21994496 PMCID: PMC3183482 DOI: 10.3389/fphys.2011.00066] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 09/13/2011] [Indexed: 11/13/2022] Open
Abstract
Aquaporins are believed to be involved in homeosmotic mechanisms of marine teleosts. Increasing data suggest that these molecular water channels play critical roles associated with the adaptation of gametes and early embryos to the external spawning environment. In this mini-review, we discuss recent studies suggesting the function of aquaporin-mediated fluid homeostasis during spermatozoa activation and egg formation in teleosts. In addition, we address the potential role of water channels in osmosensing and cell migration during early embryonic development.
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Affiliation(s)
- François Chauvigné
- Laboratory of Institut de Recerca i Tecnologia Agroalimentàries, Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas Barcelona, Spain
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Madsen SS, Olesen JH, Bedal K, Engelund MB, Velasco-Santamaría YM, Tipsmark CK. Functional characterization of water transport and cellular localization of three aquaporin paralogs in the salmonid intestine. Front Physiol 2011; 2:56. [PMID: 21941512 PMCID: PMC3171111 DOI: 10.3389/fphys.2011.00056] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/17/2011] [Indexed: 01/05/2023] Open
Abstract
Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along with an investigation of the distribution and cellular localization of three aquaporins (Aqp1aa, -1ab, and -8ab) in pyloric caeca, middle (M), and posterior (P) intestine of the Atlantic salmon. In vitro iso-osmotic water absorption (J(v)) was higher in SW than FW-trout and was inhibited by (mmol L(-1)): 0.1 KCN (41%), 0.1 ouabain (72%), and 0.1 bumetanide (82%) suggesting that active transport, Na(+), K(+)-ATPase and Na(+), K(+), 2Cl(-)-co-transport are involved in establishing the driving gradient for water transport. J(v) was also inhibited by 1 mmol L(-1) HgCl(2), serosally (23% in M and 44% in P), mucosally (27% in M), or both (61% in M and 58% in P), suggesting involvement of both apical and basolateral aquaporins in water transport. The inhibition was antagonized by 5 mmol L(-1) mercaptoethanol. By comparison, 10 mmol L(-1) mucosal tetraethylammonium, an inhibitor of certain aquaporins, inhibited J(v) by 20%. In the presence of glucose, mucosal addition of phloridzin inhibited water transport by 20%, suggesting that water transport is partially linked to the Na(+)-glucose co-transporter. Using polyclonal antibodies against salmon Aqp1aa, -1ab, and -8ab, we detected Aqp1aa, and -1ab immunoreactivity in the brush border and sub-apical region of enterocytes in all intestinal segments. The Aqp8ab antibody showed a particularly strong immunoreaction in the brush border and sub-apical region of enterocytes throughout the intestine and also stained lateral membranes and peri-nuclear regions though at lower intensity. The present localization of three aquaporins in both apical and lateral membranes of salmonid enterocytes facilitates a model for transcellular water transport in the intestine of SW-acclimated salmonids.
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Affiliation(s)
- Steffen S Madsen
- Institute of Biology, University of Southern Denmark Odense, Denmark
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Deane EE, Luk JCY, Woo NYS. Aquaporin 1a expression in gill, intestine, and kidney of the euryhaline silver sea bream. Front Physiol 2011; 2:39. [PMID: 21811469 PMCID: PMC3143732 DOI: 10.3389/fphys.2011.00039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/09/2011] [Indexed: 01/28/2023] Open
Abstract
This study aimed to investigate the effects of chronic salinity acclimation, abrupt salinity transfer, and cortisol administration on aquaporin 1 (AQP1) expression in gill, intestine, and kidney of silver sea bream (Sparus sarba). An AQP1a cDNA was cloned and found to share 83-96% amino acid sequence identity with AQP1 genes from several fish species. Tissue distribution studies of AQP1a mRNA demonstrated that it was expressed in gill, liver, intestine, rectum, kidney, heart, urinary bladder, and whole blood. Semi-quantitative RT-PCR analysis was used to measure AQP1a transcript abundance in sea bream that were acclimated to salinity conditions of 0, 6, 12, 33, 50, and 70 ppt for 1 month. The abundance of gill AQP1a transcript was highest in sea bream acclimated to 0 ppt whereas no differences were found among 0-50 ppt groups. For intestine, the highest AQP1a transcript amounts were found in sea bream acclimated to 12 and 70 ppt whereas the transcript abundance of kidney AQP1a was found to be unchanged amongst the different salinity groups. To investigate the effects of acute salinity alterations on AQP1a expression, sea bream were abruptly transferred from 33 to 6 ppt. For intestine AQP1a levels were altered at different times, post transfer, but remained unchanged in gill and kidney. To study the effects of cortisol on AQP1a expression, sea bream were administered a single dose of cortisol followed by a 3-day acclimation to either 33 or 6 ppt. The findings from this experiment demonstrated that cortisol administration resulted in alterations of AQP1a transcript in gill and intestine but not in kidney.
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Affiliation(s)
- Eddie E Deane
- School of Life Sciences, The Chinese University of Hong Kong Hong Kong, China
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Giffard-Mena I, Boulo V, Abed C, Cramb G, Charmantier G. Expression and Localization of Aquaporin 1a in the Sea-Bass (Dicentrarchus labrax) during Ontogeny. Front Physiol 2011; 2:34. [PMID: 21808622 PMCID: PMC3137954 DOI: 10.3389/fphys.2011.00034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 06/20/2011] [Indexed: 01/24/2023] Open
Abstract
The successful establishment of a species in a given habitat depends on the ability of each of its developing stages to adapt to the environment. In order to understand this process we have studied the adaptation of a euryhaline fish, the sea-bass Dicentrarchus labrax, to various salinities during its ontogeny. The expression and localization of Aquaporin 1a (AQP1a) mRNA and protein were determined in different osmoregulatory tissues. In larvae, the sites of AQP1a expression are variable and they shift according to age, implying functional changes. In juveniles after metamorphosis (D32-D48 post-hatch, 15-25 mm) and in pre-adults, an increase in AQP1a transcript abundance was noted in the digestive tract, and the AQP1a location was observed in the intestine. In juveniles (D87-D100 post-hatch, 38-48 mm), the transcript levels of AQP1a in the digestive tract and in the kidney were higher in sea water (SW) than at lower salinity. These observations, in agreement with existing models, suggest that in SW-acclimated fish, the imbibed water is absorbed via AQP1a through the digestive tract, particularly the intestine and the rectum. In addition, AQP1a may play a role in water reabsorption in the kidney. These mechanisms compensate dehydration in SW, and they contribute to the adaptation of juveniles to salinity changes during sea-lagoon migrations. These results contribute to the interpretation of the adaptation of populations to habitats where salinity varies.
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Affiliation(s)
- Ivone Giffard-Mena
- Molecular Ecology Laboratory, Universidad Autónoma de Baja CaliforniaEnsenada, Baja California, Mexico
| | - Viviane Boulo
- Adaptation Ecophysiologique et Ontogenèse Team, UMR5119, CNRS, IFREMER Ecosym, Université Montpellier 2Montpellier, France
| | - Charline Abed
- Adaptation Ecophysiologique et Ontogenèse Team, UMR5119, CNRS, IFREMER Ecosym, Université Montpellier 2Montpellier, France
| | - Gordon Cramb
- School of Biology, University of St AndrewsSt Andrews, Fife, UK
| | - Guy Charmantier
- Adaptation Ecophysiologique et Ontogenèse Team, UMR5119, CNRS, IFREMER Ecosym, Université Montpellier 2Montpellier, France
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Cerdà J, Finn RN. Piscine aquaporins: an overview of recent advances. ACTA ACUST UNITED AC 2010; 313:623-50. [PMID: 20717996 DOI: 10.1002/jez.634] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 06/15/2010] [Accepted: 06/29/2010] [Indexed: 11/08/2022]
Abstract
Aquaporins are a superfamily of integral membrane proteins that facilitate the rapid and yet highly selective flux of water and other small solutes across biological membranes. Since their discovery, they have been documented throughout the living biota, with the majority of research focusing on mammals and plants. Here, we review available data for piscine aquaporins, including Agnatha (jawless fish), Chondrichthyes (chimaeras, sharks, and rays), Dipnoi (lungfishes), and Teleostei (ray-finned bony fishes). Recent evidence suggests that the aquaporin superfamily has specifically expanded in the chordate lineage consequent to serial rounds of whole genome duplication, with teleost genomes harboring the largest number of paralogs. The selective retention and dichotomous clustering of most duplicated paralogs in Teleostei, with differential tissue expression profiles, implies that novel or specialized physiological functions may have evolved in this clade. The recently proposed new nomenclature of the piscine aquaporin superfamily is discussed in relation to the phylogenetic signal and genomic synteny, with the teleost aquaporin-8 paralogs used as a case study to illustrate disparities between the underlying codons, molecular phylogeny, and physical locus. Structural data indicate that piscine aquaporins display similar channel restriction residues found in the tetrapod counterparts, and hence their functional properties seem to be conserved. However, emerging evidence suggests that regulation of aquaporin function in teleosts may have diverged in some cases. Cell localization and experimental studies imply that the physiological roles of piscine aquaporins extend at least to osmoregulation, reproduction, and early development, although in most cases their specific functions remain to be elucidated.
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Affiliation(s)
- Joan Cerdà
- Laboratory of Institut de Recerca i Tecnologia Agroalimentàries (IRTA)- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain.
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Kalujnaia S, McVee J, Kasciukovic T, Stewart AJ, Cramb G. A role for inositol monophosphatase 1 (IMPA1) in salinity adaptation in the euryhaline eel (Anguilla anguilla). FASEB J 2010; 24:3981-91. [PMID: 20547660 DOI: 10.1096/fj.10-161000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study investigated the expression and tissue distribution of inositol monophosphatase (IMPA1) and characterized its role in salinity adaptation in the eel. The coding sequence of eel IMPA1 was determined and confirmed to be orthologous to the mammalian gene/enzyme by phylogenetic analysis and structural modeling. Quantitative real-time PCR and Western blot techniques indicated up to 17-fold increases in mRNA expression and 2-fold increases in protein abundance in major osmoregulatory tissues following transfer of fish to seawater (SW). This was accompanied by up to 5-fold increases in enzyme activity, and 1.8- and 3-fold increases in inositol contents within the gill and kidney, respectively. Immunohistological studies revealed that IMPA1 protein expression predominated in SW-acclimated fish within basal epithelial/epidermal layers of the gill, esophagus, intestine, skin, and fins. SW transfer also induced a 10-fold increase in inositol content in the fin. IMPA1 immunoreactivity was also identified in chondrocytes within the cartilagenous matrix of the gills and fins, as well as in clusters of interstitial cells surrounding the kidney tubules. The observed increases in expression of IMPA1 highlight a protective role for inositol within various eel tissues following SW acclimation. This constitutes an adaptive mechanism in teleost fish naturally exposed to hypertonic environments.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St Andrews, St Andrews, Fife, KY16 9TF, UK
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Tingaud-Sequeira A, Calusinska M, Finn RN, Chauvigné F, Lozano J, Cerdà J. The zebrafish genome encodes the largest vertebrate repertoire of functional aquaporins with dual paralogy and substrate specificities similar to mammals. BMC Evol Biol 2010; 10:38. [PMID: 20149227 PMCID: PMC2829555 DOI: 10.1186/1471-2148-10-38] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 02/11/2010] [Indexed: 01/15/2023] Open
Abstract
Background Aquaporins are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. These proteins are vital for maintaining water homeostasis in living organisms. In mammals, thirteen aquaporins (AQP0-12) have been characterized, but in lower vertebrates, such as fish, the diversity, structure and substrate specificity of these membrane channel proteins are largely unknown. Results The screening and isolation of transcripts from the zebrafish (Danio rerio) genome revealed eighteen sequences structurally related to the four subfamilies of tetrapod aquaporins, i.e., aquaporins (AQP0, -1 and -4), water and glycerol transporters or aquaglyceroporins (Glps; AQP3 and AQP7-10), a water and urea transporter (AQP8), and two unorthodox aquaporins (AQP11 and -12). Phylogenetic analyses of nucleotide and deduced amino acid sequences demonstrated dual paralogy between teleost and human aquaporins. Three of the duplicated zebrafish isoforms have unlinked loci, two have linked loci, while DrAqp8 was found in triplicate across two chromosomes. Genomic sequencing, structural analysis, and maximum likelihood reconstruction, further revealed the presence of a putative pseudogene that displays hybrid exons similar to tetrapod AQP5 and -1. Ectopic expression of the cloned transcripts in Xenopus laevis oocytes demonstrated that zebrafish aquaporins and Glps transport water or water, glycerol and urea, respectively, whereas DrAqp11b and -12 were not functional in oocytes. Contrary to humans and some rodents, intrachromosomal duplicates of zebrafish AQP8 were water and urea permeable, while the genomic duplicate only transported water. All aquaporin transcripts were expressed in adult tissues and found to have divergent expression patterns. In some tissues, however, redundant expression of transcripts encoding two duplicated paralogs seems to occur. Conclusion The zebrafish genome encodes the largest repertoire of functional vertebrate aquaporins with dual paralogy to human isoforms. Our data reveal an early and specific diversification of these integral membrane proteins at the root of the crown-clade of Teleostei. Despite the increase in gene copy number, zebrafish aquaporins mostly retain the substrate specificity characteristic of the tetrapod counterparts. Based upon the integration of phylogenetic, genomic and functional data we propose a new classification for the piscine aquaporin superfamily.
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Affiliation(s)
- Angèle Tingaud-Sequeira
- Laboratory of Institut de Recerca i Tecnologia Agroalimentàries-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, 08003 Barcelona, Spain
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Tipsmark CK, Sørensen KJ, Madsen SS. Aquaporin expression dynamics in osmoregulatory tissues of Atlantic salmon during smoltification and seawater acclimation. J Exp Biol 2010; 213:368-79. [DOI: 10.1242/jeb.034785] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
SUMMARY
Osmotic balance in fish is maintained through the coordinated regulation of water and ion transport performed by epithelia in intestine, kidney and gill. In the current study, six aquaporin (AQP) isoforms found in Atlantic salmon (Salmo salar) were classified and their tissue specificity and mRNA expression in response to a hyperosmotic challenge and during smoltification were examined. While AQP-1a was generic, AQP-1b had highest expression in kidney and AQP-3 was predominantly found in oesophagus, gill and muscle. Two novel teleost isoforms, AQP-8a and -8b, were expressed specifically in liver and intestinal segments, respectively. AQP-10 was predominantly expressed in intestinal segments, albeit at very low levels. Transfer from freshwater (FW) to seawater (SW) induced elevated levels of intestinal AQP-1a, -1b and -8b mRNA, whereas only AQP-8b was stimulated during smoltification. In kidney, AQP-1a, -3 and -10 were elevated in SW whereas AQP-1b was reduced compared with FW levels. Correspondingly, renal AQP-1a and -10 peaked during smoltification in April and March, respectively, as AQP-1b and AQP-3 declined. In the gill, AQP-1a and AQP-3 declined in SW whereas AQP-1b increased. Gill AQP-1a and -b peaked in April, whereas AQP-3 declined through smoltification. These reciprocal isoform shifts in renal and gill tissues may be functionally linked with the changed role of these organs in FW compared with SW. The presence and observed dynamics of the AQP-8b isoform specifically in intestinal sections suggest that this is a key water channel responsible for water uptake in the intestinal tract of seawater salmonids.
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Affiliation(s)
- C. K. Tipsmark
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - K. J. Sørensen
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - S. S. Madsen
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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MacIver B, Cutler CP, Yin J, Hill MG, Zeidel ML, Hill WG. Expression and functional characterization of four aquaporin water channels from the European eel (Anguilla anguilla). ACTA ACUST UNITED AC 2009; 212:2856-63. [PMID: 19684221 DOI: 10.1242/jeb.025882] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The European eel is a euryhaline teleost which has been shown to differentially up- and downregulate aquaporin (AQP) water channels in response to changes in environmental salinity. We have characterized the transport properties of four aquaporins localized to osmoregulatory organs - gill, esophagus, intestine and kidney. By sequence comparison these four AQP orthologs resemble human AQP1 (eel AQP1), AQP3 (eel AQP3) and AQP10 (AQPe). The fourth member is a duplicate form of AQP1 (AQP1dup) thought to arise from a duplication of the teleost genome. Using heterologous expression in Xenopus oocytes we demonstrate that all four eel orthologs transport water and are mercury inhibitable. Eel AQP3 and AQPe also transport urea and glycerol, making them aquaglyceroporins. Eel AQP3 is dramatically inhibited by extracellular acidity (91% and 69% inhibition of water and glycerol transport respectively at pH 6.5) consistent with channel gating by protons. Maximal water flux of eel AQP3 occurred around pH 8.2 - close to the physiological pH of plasma in the eel. Exposure of AQP-expressing oocytes to heavy metals revealed that eel AQP3 is highly sensitive to extracellular nickel and zinc (88.3% and 86.3% inhibition, respectively) but less sensitive to copper (56.4% inhibition). Surprisingly, copper had a stimulatory effect on eel AQP1 (153.7% activity of control). Copper, nickel and zinc did not affect AQP1dup or AQPe. We establish that all four eel AQP orthologs have similar transport profiles to their human counterparts, with eel AQP3 exhibiting some differences in its sensitivity to metals. This is the first investigation of the transport properties and inhibitor sensitivity of salinity-regulated aquaporins from a euryhaline species. Our results indicate a need to further investigate the deleterious effects of metal pollutants on AQP-containing epithelial cells of the gill and gastrointestinal tract at environmentally appropriate concentrations.
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Affiliation(s)
- Bryce MacIver
- Nephrology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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Cerdà J. Molecular pathways during marine fish egg hydration: the role of aquaporins. JOURNAL OF FISH BIOLOGY 2009; 75:2175-2196. [PMID: 20738681 DOI: 10.1111/j.1095-8649.2009.02397.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The pre-ovulatory hydration of the oocyte of marine teleosts, a unique process among vertebrates that occurs concomitantly with meiosis resumption (oocyte maturation), is a critical process for the correct development and survival of the embryo. Increasing information is available on the molecular mechanisms that control oocyte maturation in fish, but the identification of the cellular processes involved in oocyte hydration has remained long ignored. During the past few years, a number of studies have identified the major inorganic and organic osmolytes that create a transient intra-oocytic osmotic potential for hydrating the oocytes, whereas water influx was believed to occur passively. Recent work, however, has uncovered the role of a novel molecular water channel (aquaporin), designated aquaporin-1b (Aqp1b), which facilitates water permeation and resultant swelling of the oocyte. The Aqp1b belongs to a teleost-specific subfamily of water-selective aquaporins, similar to mammalian aquaporin-1 (AQP1) that has possibly evolved by duplication of a common ancestor and further neofunctionalization in oocytes of marine teleosts for water uptake. Strikingly, Aqp1b shows specific regulatory domains at the cytoplasmic tail, which are key to the vesicular trafficking and temporal insertion of Aqp1b in the oocyte plasma membrane during the phase of maximal hydration. These findings are revealing that the mechanism of oocyte hydration in marine teleosts is a highly regulated process based on the interplay between the generation of inorganic and organic osmolytes and the controlled insertion of Aqp1b in the oocyte surface. The discovery of Aqp1b in teleosts provides an important insight into the molecular basis of the production of viable eggs in marine fish.
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Affiliation(s)
- J Cerdà
- Laboratory of Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Passeig marítim 37-49, 08003 Barcelona, Spain.
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Suzuki M. Expression and localization of aquaporin-1 on the apical membrane of enterocytes in the small intestine of bottlenose dolphins. J Comp Physiol B 2009; 180:229-38. [PMID: 19705128 DOI: 10.1007/s00360-009-0397-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 07/10/2009] [Accepted: 07/27/2009] [Indexed: 01/18/2023]
Abstract
The small and large intestines are primary sites for water intake in mammals. To reveal how water is absorbed in the intestines of cetaceans, histological and molecular-biological studies were performed on the small intestine of the bottlenose dolphin, Tursiops truncatus. In histological studies using fresh specimens, obvious villi and deep crypts of Lieberkühn, lined by abundant enterocytes with microvilli and goblet cells, were observed in the mucosa. Expressions and immunolocalizations of aquaporin-1 (AQP1), a member of the water-selective channel termed AQP, were also investigated in the intestine. By reverse transcriptional polymerase chain reaction and rapid amplification of cDNA ends using RNA extracted from the dolphins' small intestines, the full length of mRNA for AQP1 was sequenced. The deductive amino acid sequence for an open reading frame showed high homologies with other mammals' AQP1, and water permeability of the protein was certified by cRNA injection to Xenopus oocytes. Immunohistochemistry showed AQP1 distribution on the apical membrane of the enterocytes, especially in the crypts. These data suggest that AQP1 is a channel protein responsible for water absorption in the small intestine of dolphins.
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Affiliation(s)
- Miwa Suzuki
- Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, 252-8510, Japan.
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Kalujnaia S, Cramb G. Regulation of Expression of the Myo-inositol Monophosphatase 1 Gene in Osmoregulatory Tissues of the European Eel Anguilla anguilla after Seawater Acclimation. Ann N Y Acad Sci 2009; 1163:433-6. [DOI: 10.1111/j.1749-6632.2009.04457.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Benga G. Water channel proteins (later called aquaporins) and relatives: past, present, and future. IUBMB Life 2009; 61:112-33. [PMID: 19165894 DOI: 10.1002/iub.156] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Water channels or water channel proteins (WCPs) are transmembrane proteins that have a specific three-dimensional structure with a pore that can be permeated by water molecules. WCPs are large families (over 450 members) that are present in all kingdoms of life. The first WCP was discovered in the human red blood cell (RBC) membrane in 1980s. In 1990s other WCPs were discovered in plants, microorganisms, various animals, and humans; and it became obvious that the WCPs belong to the superfamily of major intrinsic proteins (MIPs, over 800 members). WCPs include three subfamilies: (a) aquaporins (AQPs), which are water specific (or selective water channels); (b) aquaglyceroporins (and glycerol facilitators), which are permeable to water and/or other small molecules; and (c) "superaquaporins" or subcellular AQPs. WCPs (and MIPs) have several structural characteristics which were better understood after the atomic structure of some MIPs was deciphered. The structure-function relationships of MIPs expressed in microorganisms (bacteria, archaea, yeast, and protozoa), plants, and some multicellular animal species [nematodes, insects, fishes, amphibians, mammals (and humans)] are described. A synthetic overview on the WCPs from RBCs from various species is provided. The physiological roles of WCPs in kidney, gastrointestinal system, respiratory apparatus, central nervous system, eye, adipose tissue, skin are described, and some implications of WCPs in various diseases are briefly presented. References of detailed reviews on each topic are given. This is the first review providing in a condensed form an overview of the whole WCP field that became in the last 20 years a very hot area of research in biochemistry and molecular cell biology, with wide and increasing implications.
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Affiliation(s)
- Gheorghe Benga
- Department of Cell and Molecular Biology, Iuliu HaTieganu University of Medicine and Pharmacy Cluj-Napoca, Cluj-Napoca, Romania.
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Tingaud-Sequeira A, Chauvigné F, Fabra M, Lozano J, Raldúa D, Cerdà J. Structural and functional divergence of two fish aquaporin-1 water channels following teleost-specific gene duplication. BMC Evol Biol 2008; 8:259. [PMID: 18811940 PMCID: PMC2564943 DOI: 10.1186/1471-2148-8-259] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 09/23/2008] [Indexed: 12/31/2022] Open
Abstract
Background Teleost radiation in the oceans required specific physiological adaptations in eggs and early embryos to survive in the hyper-osmotic seawater. Investigating the evolution of aquaporins (AQPs) in these vertebrates should help to elucidate how mechanisms for water homeostasis evolved. The marine teleost gilthead sea bream (Sparus aurata) has a mammalian aquaporin-1 (AQP1)-related channel, termed AQP1o, with a specialized physiological role in mediating egg hydration. However, teleosts have an additional AQP isoform structurally more similar to AQP1, though its relationship with AQP1o is unclear. Results By using phylogenetic and genomic analyses we show here that teleosts, unlike tetrapods, have two closely linked AQP1 paralogous genes, termed aqp1a and aqp1b (formerly AQP1o). In marine teleosts that produce hydrated eggs, aqp1b is highly expressed in the ovary, whereas in freshwater species that produce non-hydrated eggs, aqp1b has a completely different expression pattern or is not found in the genome. Both Aqp1a and Aqp1b are functional water-selective channels when expressed in Xenopus laevis oocytes. However, expression of chimeric and mutated proteins in oocytes revealed that the sea bream Aqp1b C-terminus, unlike that of Aqp1a, contains specific residues involved in the control of Aqp1b intracellular trafficking through phosphorylation-independent and -dependent mechanisms. Conclusion We propose that 1) Aqp1a and Aqp1b are encoded by distinct genes that probably originated specifically in the teleost lineage by duplication of a common ancestor soon after divergence from tetrapods, 2) Aqp1b possibly represents a neofunctionalized AQP adapted to oocytes of marine and catadromous teleosts, thereby contributing to a water reservoir in eggs and early embryos that increases their survival in the ocean, and 3) Aqp1b independently acquired regulatory domains in the cytoplasmatic C-terminal tail for the specific control of Aqp1b expression in the plasma membrane.
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Affiliation(s)
- Angèle Tingaud-Sequeira
- Laboratory of Institut de Recerca i Tecnologia Agroalimentàries-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, 08003 Barcelona, Spain.
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Raldúa D, Otero D, Fabra M, Cerdà J. Differential localization and regulation of two aquaporin-1 homologs in the intestinal epithelia of the marine teleostSparus aurata. Am J Physiol Regul Integr Comp Physiol 2008; 294:R993-1003. [DOI: 10.1152/ajpregu.00695.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aquaporin (AQP)-mediated intestinal water absorption may play a major osmoregulatory role in euryhaline teleosts, although the molecular identity and anatomical distribution of AQPs in the fish gastrointestinal tract is poorly known. Here, we have investigated the functional properties and cellular localization in the intestine of two gilthead seabream ( Sparus aurata) homologs of mammalian aquaporin-1 (AQP1), named SaAqp1a and SaAqp1b. Heterologous expression in Xenopus laevis oocytes showed that SaAqp1a and SaAqp1b were water-selective channels. Real-time quantitative RT-PCR and Western blot using specific antisera indicated that abundance of SaAqp1a mRNA and protein was higher in duodenum and hindgut than in the rectum, whereas abundance of SaAqp1b was higher in rectum. In duodenum and hindgut, SaAqp1a localized at the apical brush border and lateral membrane of columnar enterocytes, whereas SaAqp1b was detected occasionally and at very low levels at the apical membrane. In the rectum, however, SaAqp1a was mainly accumulated in the cytoplasm of a subpopulation of enterocytes spread in groups over the surface of the epithelia, including the intervillus pockets, whereas SaAqp1b was detected exclusively at the apical brush border of all rectal enterocytes. Freshwater acclimation reduced the synthesis of SaAqp1a protein in all intestinal segments, but it only reduced SaAqp1b abundance in the rectum. These results show for the first time in teleosts a differential distribution and regulation of two functional AQP1 homologs in the intestinal epithelium, which suggest that they may play specialized functions during water movement across the intestine.
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Kurita Y, Nakada T, Kato A, Doi H, Mistry AC, Chang MH, Romero MF, Hirose S. Identification of intestinal bicarbonate transporters involved in formation of carbonate precipitates to stimulate water absorption in marine teleost fish. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1402-12. [PMID: 18216137 DOI: 10.1152/ajpregu.00759.2007] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Marine teleost fish precipitate divalent cations as carbonate deposits in the intestine to minimize the potential for excessive Ca2+ entry and to stimulate water absorption by reducing luminal osmotic pressure. This carbonate deposit formation, therefore, helps maintain osmoregulation in the seawater (SW) environment and requires controlled secretion of HCO3(-) to match the amount of Ca2+ entering the intestinal lumen. Despite its physiological importance, the process of HCO3(-) secretion has not been characterized at the molecular level. We analyzed the expression of two families of HCO3(-) transporters, Slc4 and Slc26, in fresh-water- and SW-acclimated euryhaline pufferfish, mefugu (Takifugu obscurus), and obtained the following candidate clones: NBCe1 (an Na+-HCO3(-) cotransporter) and Slc26a6A and Slc26a6B (putative Cl(-)/HCO3(-) exchangers). Heterologous expression in Xenopus oocytes showed that Slc26a6A and Slc26a6B have potent HCO3(-)-transporting activity as electrogenic Cl(-)/nHCO3(-) exchangers, whereas mefugu NBCe1 functions as an electrogenic Na+-nHCO3(-) cotransporter. Expression of NBCe1 and Slc26a6A was highly induced in the intestine in SW and expression of Slc26a6B was high in the intestine in SW and fresh water, suggesting their involvement in HCO3(-) secretion and carbonate precipitate formation. Immunohistochemistry showed staining on the apical (Slc26a6A and Slc26a6B) and basolateral (NBCe1) membranes of the intestinal epithelial cells in SW. We therefore propose a mechanism for HCO3(-) transport across the intestinal epithelial cells of marine fish that includes basolateral HCO3(-) uptake (NBCe1) and apical HCO3(-) secretion (Slc26a6A and Slc26a6B).
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Affiliation(s)
- Yukihiro Kurita
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B-19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
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Kalujnaia S, McWilliam IS, Zaguinaiko VA, Feilen AL, Nicholson J, Hazon N, Cutler CP, Cramb G. Transcriptomic approach to the study of osmoregulation in the European eel Anguilla anguilla. Physiol Genomics 2007; 31:385-401. [PMID: 17666525 DOI: 10.1152/physiolgenomics.00059.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In euryhaline teleosts, osmoregulation is a fundamental and dynamic process that is essential for the maintenance of ion and water balance, especially when fish migrate between fresh water (FW) and sea water (SW) environments. The European eel has proved to be an excellent model species to study the molecular and physiological adaptations associated with this osmoregulatory plasticity. The life cycle of the European eel includes two migratory periods, the second being the migration of FW eels back to the Sargasso Sea for reproduction. Various anatomical and physiological changes allow the successful transition to SW. The aim of this study was to use a microarray approach to screen the osmoregulatory tissues of the eel for changes in gene expression following acclimation to SW. Tissues were sampled from fish at selected intervals over a 5-mo period following FW/SW transfer, and RNA was isolated. Suppressive subtractive hybridization was used for enrichment of differentially expressed genes. Microarrays comprising 6,144 cDNAs from brain, gill, intestine, and kidney libraries were hybridized with appropriate targets and analyzed; 229 differentially expressed clones with unique sequences were identified. These clones represented the sequences for 95 known genes, with the remaining sequences (59%) being unknown. The results of the microarray analysis were validated by quantification of 28 differentially expressed genes by Northern blotting. A number of the differentially expressed genes were already known to be involved in osmoregulation, but the functional roles of many others, not normally associated with ion or water transport, remain to be characterized.
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Giffard-Mena I, Boulo V, Aujoulat F, Fowden H, Castille R, Charmantier G, Cramb G. Aquaporin molecular characterization in the sea-bass (Dicentrarchus labrax): the effect of salinity on AQP1 and AQP3 expression. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:430-44. [PMID: 17618150 DOI: 10.1016/j.cbpa.2007.06.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 12/20/2022]
Abstract
Euryhaline fish possess the ability to compensate for environmental salinity changes through hydro-mineral regulation. A number of proteins have been studied in order to understand water and ion exchanges, known as fish osmoregulation. Sea-bass (Dicentrarchus labrax) cDNA sequences encoding a homologue of mammalian aquaporin (termed AQP1) and a homologue of mammalian aquaglyceroporin (termed AQP3) have been isolated and sequenced. The aquaporin amino acid sequences share respectively more than 60% and 65% identity with other known aquaporins. We have shown that salinity influences aquaporin expression levels in the gill, kidney and digestive tract, the main osmoregulatory organs. AQP1 may have a major osmoregulatory role in water transport in kidney and gut in SW-acclimated fish, whereas AQP3 could be implicated in gill water transport in FW-acclimated fish.
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Affiliation(s)
- Ivone Giffard-Mena
- AEO team, UMR 5119 Ecolag, Université Montpellier II, Montpellier Cedex 05, 34095, France.
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Veillette PA, Breves JP, Reardon DR, Specker JL. Adaptation for water balance in the partial gastrointestinal tract of summer flounder. Comp Biochem Physiol A Mol Integr Physiol 2006; 143:211-7. [PMID: 16423546 DOI: 10.1016/j.cbpa.2005.11.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 11/23/2005] [Accepted: 11/23/2005] [Indexed: 10/25/2022]
Abstract
Marine teleosts continually drink and absorb water across the intestine to prevent dehydration. Surprisingly, summer flounder that are missing most of their intestine, due to necrotizing enteritis, maintain osmotic homeostasis. Here, we tested the hypothesis that this remnant gastrointestinal tract undergoes compensatory adaptation for fluid uptake. Flounder (Paralicthys dentatus) with a partial gastrointestinal tract had an emaciated liver. Moisture content of muscle however was similar to healthy cohorts with an intact gastrointestinal tract, indicative of an undisturbed osmoregulatory status. Mass-specific rates of fluid uptake across all segments of the partial gastrointestinal tract were less than or similar to rates in corresponding segments from intact flounder. In contrast, weights (percent of body mass) were doubled in stomach and partial intestine of the remnant gastrointestinal tract. Consequently, total capacity for fluid uptake (microL h(-1) g body mass(-1)) was similar for both groups. The functional capacity of the remnant gastrointestinal tract was therefore of a magnitude sufficient to maintain osmoregulatory ability, further evidencing a critical role of the intestine in salt and water balance of marine teleosts.
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Affiliation(s)
- Philip A Veillette
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882-1197, United States.
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Kato A, Doi H, Nakada T, Sakai H, Hirose S. Takifugu obscurus is a euryhaline fugu species very close to Takifugu rubripes and suitable for studying osmoregulation. BMC PHYSIOLOGY 2005; 5:18. [PMID: 16364184 PMCID: PMC1351200 DOI: 10.1186/1472-6793-5-18] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Accepted: 12/20/2005] [Indexed: 11/25/2022]
Abstract
Background The genome sequence of the pufferfish Takifugu rubripes is an enormously useful tool in the molecular physiology of fish. Euryhaline fish that can survive both in freshwater (FW) and seawater (SW) are also very useful for studying fish physiology, especially osmoregulation. Recently we learned that there is a pufferfish, Takifugu obscurus, common name "mefugu" that migrates into FW to spawn. If T. obscurus is indeed a euryhaline fish and shares a high sequence homology with T. rubripes, it will become a superior animal model for studying the mechanism of osmoregulation. We have therefore determined its euryhalinity and phylogenetic relationship to the members of the Takifugu family. Results The following six Takifugu species were used for the analyses: T. obscurus, T. rubripes, T. niphobles, T. pardalis, T. poecilonotus, and T. porphyreus. When transferred to FW, only T. obscurus could survive while the others could not survive more than ten days in FW. During this course of FW adaptation, serum Na+ concentration of T. obscurus decreased only slightly, but a rapid and large decrease occurred even in the case of T. niphobles, a peripheral fresh water species that is often seen in brackish river mouths. Phylogenetic analysis using nucleotide sequences of the mitochondrial 16S ribosomal RNA gene of each species indicated that the six Takifugu species are very closely related with each other. Conclusion T. obscurus is capable of adapting to both FW and SW. Its genomic sequence shares a very high homology with those of the other Takifugu species such that the existing Takifugu genomic information resources can be utilized. These properties make "mefugu", which has drawn little attention from animal physiologists until this study, a useful model animal for studying the molecular mechanism of maintaining body fluid homeostasis.
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Affiliation(s)
- Akira Kato
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroyuki Doi
- Shimonoseki Marine Science Museum "Kaikyokan", Shimonoseki Academy of Marine Science, Shimonoseki, Japan
| | - Tsutomu Nakada
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan
| | - Harumi Sakai
- Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Japan
| | - Shigehisa Hirose
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan
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