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Weinrauch AM, Anderson WG. In situ method for the determination of nutrient acquisition and its hormonal regulation in the spiral valve of two chondrichthyan fishes. Am J Physiol Regul Integr Comp Physiol 2023; 325:R546-R555. [PMID: 37642282 DOI: 10.1152/ajpregu.00109.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 08/17/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023]
Abstract
Chondrichthyans play an important role in nutrient cycling of many marine ecosystems, yet little is known about their nutritional physiology particularly relating to nutrient acquisition in the spiral valve intestine. This unique organ poses challenges for examining nutrient transport physiology using traditional reductionist methods owing to its scroll-like morphology. Thus, we established a method for the characterization of nutrient uptake rates in two representative chondrichthyans, the Pacific spiny dogfish (Squalus suckleyi) and the Pacific spotted ratfish (Hydrolagus colliei). We validated a dual-cannulation method wherein perfusate was circulated through the vasculature of the spiral valve via the anterior and posterior intestinal arteries, and [14C]glucose or [3H]oleic acid was accumulated from the static spiral valve lumen into the anterior and posterior intestinal veins. Radiotracer accumulated at a stable rate in the venous effluent in comparison with measures of mucosal disappearance. Interestingly, similar anterior and posterior glucose uptake was observed in dogfish, yet significantly more oleic acid was accumulated in the posterior veins of ratfish. Further validation of the preparation in dogfish demonstrated sodium dependence of glucose transport as well as an effect of bovine insulin administration to the arterial circulation. Each of these manipulations resulted in significant differences in glucose handling between the anterior and posterior veins, suggestive of heretofore unknown heterogenous functions along the intestine. This preparation demonstrates a new and reliable method for the measurement of nutrient acquisition and regulation thereof in a unique digestive organ. Furthermore, it presents avenues for investigation of differential functional along the spiral valve.NEW & NOTEWORTHY We describe a novel dual cannulation method for investigating radiolabeled nutrient uptake from a unique organ, the spiral valve. Furthermore, we identify functional differences in nutrient transport along the length of the spiral valve which consists of a homogenous gross morphology. Finally, this method reveals a useful way in which to manipulate the arterial supply to better understand postprandial physiology as it varies with metabolites and endocrine factors.
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Affiliation(s)
- Alyssa M Weinrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
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Rankins DR, Herrera MJ, Christensen MP, Chen A, Hood NZ, Heras J, German DP. When digestive physiology doesn't match "diet": Lumpenus sagitta (Stichaeidae) is an "omnivore" with a carnivorous gut. Comp Biochem Physiol A Mol Integr Physiol 2023; 285:111508. [PMID: 37625480 DOI: 10.1016/j.cbpa.2023.111508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 08/21/2023] [Accepted: 08/21/2023] [Indexed: 08/27/2023]
Abstract
What an animal ingests and what it digests can be different. Thus, we examined the nutritional physiology of Lumpenus sagitta, a member of the family Stichaeidae, to better understand whether it could digest algal components like its better studied algivorous relatives. Although L. sagitta ingests considerable algal content, we found little evidence of algal digestion. This fish species has a short gut that doesn't show positive allometry with body size, low amylolytic activity that actually decreases as the fish grow, no ontogenetic changes in digestive enzyme gene expression, elevated N-acetyl-glucosaminidase activity (indicative of chitin breakdown), and an enteric microbial community that is consistent with carnivory and differs from members of its family that consume and digest algae. Hence, we are left concluding that L. sagitta is not capable of digesting the algae it consumes, and instead, are likely targeting epibionts on the algae itself, and other invertebrates consumed with the algae. Our study expands the coverage of dietary and digestive information for the family Stichaeidae, which is becoming a model for fish digestive physiology and genomics, and shows the power of moving beyond gut content analyses to better understand what an animal can actually digest and use metabolically.
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Affiliation(s)
- Daniel R Rankins
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA.
| | - Michelle J Herrera
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Michelle P Christensen
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Alisa Chen
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Newton Z Hood
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Joseph Heras
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| | - Donovan P German
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
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Bosi G, Merella P, Maynard BJ, Sayyaf Dezfuli B. Microscopic Characterization of the Mucous Cells and Their Mucin Secretions in the Alimentary Canal of the Blackmouth Catshark Galeus melastomus (Chondrichthyes: Elasmobranchii). Fishes 2022; 7:8. [DOI: 10.3390/fishes7010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sharks belong to the most primitive group of jawed vertebrates and have some special structural and functional features such as a cartilaginous skeleton, a spiral intestinal valve, and a rectal gland for osmoregulation. In January 2020, ten specimens of Galeus melastomus, the Blackmouth catshark, were collected from the Gulf of Asinara (North Sardinia, Italy) and the entire alimentary canal was studied using histochemical reactions to characterize the mucous cell types. In the alimentary canal of G. melastomus, mucous cells mainly secrete a mixture of acidic and neutral mucins. Of the acidic mucins, only the carboxylated type was present in mucous cells of the stomach, while the sulfated type predominated in the esophagus and the intestines. The use of lectins revealed a distribution of sugar residues in mucins related to cellular activities of the different regions of the catshark alimentary canal. The current study is the first report to characterize the intestinal mucous cells of G. melastomus and to provide quantitative data on their different populations in the alimentary canal.
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Honda Y, Takagi W, Wong MKS, Ogawa N, Tokunaga K, Kofuji K, Hyodo S. Morphological and functional development of the spiral intestine in cloudy catshark ( Scyliorhinus torazame). J Exp Biol 2020; 223:jeb225557. [PMID: 32527960 DOI: 10.1242/jeb.225557] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
Cartilaginous fish have a comparatively short intestine known as the spiral intestine that consists of a helical spiral of intestinal mucosa. However, morphological and functional development of the spiral intestine has not been fully described. Unlike teleosts, cartilaginous fish are characterized by an extremely long developmental period in ovo or in utero; for example, in the oviparous cloudy catshark (Scyliorhinus torazame), the developing fish remains inside the egg capsule for up to 6 months, suggesting that the embryonic intestine may become functional prior to hatching. In the present study, we describe the morphological and functional development of the spiral intestine in the developing catshark embryo. Spiral formation of embryonic intestine was completed at the middle of stage 31, prior to 'pre-hatching', which is a developmental event characterized by the opening of the egg case at the end of the first third of development. Within 48 h of the pre-hatching event, egg yolk began to flow from the external yolk sac into the embryonic intestine via the yolk stalk. At the same time, there was a rapid increase in mRNA expression of the peptide transporter pept1 and neutral amino acid transporter slc6a19 Secondary folds in the intestinal mucosa and microvilli on the apical membrane appeared after pre-hatching, further supporting the onset of nutrient absorption in the developing intestine at this time. We demonstrate the acquisition of intestinal nutrient absorption at the pre-hatching stage of an oviparous elasmobranch.
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Affiliation(s)
- Yuki Honda
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Wataru Takagi
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Marty K S Wong
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Nobuhiro Ogawa
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Kotaro Tokunaga
- Ibaraki Prefectural Oarai Aquarium, Oarai, Ibaraki 311-1301, Japan
| | - Kazuya Kofuji
- Ibaraki Prefectural Oarai Aquarium, Oarai, Ibaraki 311-1301, Japan
| | - Susumu Hyodo
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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Luo WJ, Song P, He ZM, Cao SP, Tang JZ, Xu WQ, Xiong D, Qu FF, Zhao DF, Liu Z, Li JZ, Yin YL. JAK2 Mediates the Regulation of Pept1 Expression by Leptin in the Grass Carp ( Ctenopharyngodon idella) Intestine. Front Physiol 2020; 11:79. [PMID: 32116786 PMCID: PMC7033393 DOI: 10.3389/fphys.2020.00079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 01/23/2020] [Indexed: 11/17/2022] Open
Abstract
Oligopeptide transporter 1 (Pept1) is located on the brush border membrane of the intestinal epithelium and plays an important role in dipeptide and tripeptide absorption from protein digestion. In this study, we cloned and characterized the cDNA sequence of Janus kinase 2 (JAK2) from Ctenopharyngodon idella. The expression patterns of JAK2 in various tissues and developmental stages were characterized by quantitative real-time PCR (qRT-PCR). The mRNA expression levels of JAK2 and Pept1 regulated by leptin in the intestine were also analyzed in vitro and in vivo. The cDNA sequence of JAK2 is 3378 bp in length, and the mRNA of JAK2 was broadly expressed in all tissues and embryonic stages of C. idella analyzed. In addition, we found that leptin regulated expression of JAK2 and Pept1 in the intestine; Pept1 expression was down-regulated by the JAK2 inhibitor AG490 in vivo and in vitro. Furthermore, luciferase experiments showed that overexpression of the JAK2 gene significantly upregulated the activity of the Pept1 5′ regulatory sequence in C. idella. In conclusion, these results may help in elucidating the regulatory effect of the leptin-mediated JAK2 pathway on intestinal Pept1 expression in C. idella and the molecular mechanism of peptide transport by the intestinal transporter Pept1 in fishes.
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Affiliation(s)
- Wen-Jie Luo
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China.,Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Hunan Normal University, Changsha, China
| | - Peng Song
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Zhi-Min He
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Shen-Ping Cao
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Jian-Zhou Tang
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Wen-Qian Xu
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Ding Xiong
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Fu-Fa Qu
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Da-Fang Zhao
- Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Hunan Normal University, Changsha, China
| | - Zhen Liu
- Hunan Provincial Key Laboratory of Nutrition and Quality Control of Aquatic Animals, Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Jian-Zhong Li
- Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Hunan Normal University, Changsha, China
| | - Yu-Long Yin
- Hunan International Joint Laboratory of Animal Intestinal Ecology and Health, Hunan Normal University, Changsha, China
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Leigh SC, Papastamatiou YP, German DP. Seagrass digestion by a notorious 'carnivore'. Proc Biol Sci 2018; 285:rspb.2018.1583. [PMID: 30185641 DOI: 10.1098/rspb.2018.1583] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/13/2018] [Indexed: 02/06/2023] Open
Abstract
What an animal consumes and what an animal digests and assimilates for energetic demands are not always synonymous. Sharks, uniformly accepted as carnivores, have guts that are presumed to be well suited for a high-protein diet. However, the bonnethead shark (Sphyrna tiburo), which is abundant in critical seagrass habitats, has been previously shown to consume copious amounts of seagrass (up to 62.1% of gut content mass), although it is unknown if they can digest and assimilate seagrass nutrients. To determine if bonnetheads digest seagrass nutrients, captive sharks were fed a 13C-labelled seagrass diet. Digestibility analyses, digestive enzyme assays and stable isotope analyses were used to determine the bonnethead shark's capacity for digesting and assimilating seagrass material. Compound-specific stable isotope analysis showed that sharks assimilated seagrass carbon (13.6 ± 6.77‰ δ13C mean ± s.d. for all sharks and all amino acid types analysed) with 50 ± 2% digestibility of seagrass organic matter. Additionally, cellulose-component-degrading enzyme activities were detected in shark hindguts. We show that a coastal shark is digesting seagrass with at least moderate efficiency, which has ecological implications due to the stabilizing role of omnivory and nutrient transport within fragile seagrass ecosystems.
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Affiliation(s)
- Samantha C Leigh
- Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA 92697, USA
| | - Yannis P Papastamatiou
- Marine Sciences Program, Department of Biological Science, Florida International University, 3000 NE 151st Street, Miami, FL 33181, USA
| | - Donovan P German
- Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA 92697, USA
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Con P, Nitzan T, Cnaani A. Salinity-Dependent Shift in the Localization of Three Peptide Transporters along the Intestine of the Mozambique Tilapia ( Oreochromis mossambicus). Front Physiol 2017; 8:8. [PMID: 28167916 PMCID: PMC5253378 DOI: 10.3389/fphys.2017.00008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/05/2017] [Indexed: 12/15/2022] Open
Abstract
The peptide transporter (PepT) systems are well-known for their importance to protein absorption in all vertebrate species. These symporters use H+ gradient at the apical membrane of the intestinal epithelial cells to mediate the absorption of small peptides. In fish, the intestine is a multifunctional organ, involved in osmoregulation, acid-base regulation, and nutrient absorption. Therefore, we expected environmental stimuli to affect peptide absorption. We examined the effect of three environmental factors; salinity, pH and feeding, on the expression, activity and localization of three PepT transporters (PepT1a, PepT1b, PepT2) along the intestine of the Mozambique tilapia (Oreochromis mossambicus). Quantitative real time PCR (qPCR) analysis demonstrated that the two PepT1 variants are typical to the proximal intestinal section while PepT2 is typical to the distal intestinal sections. Immunofluorescence analysis with custom-made antibodies supported the qPCR results, localized both transporters on the apical membrane of enterocytes and provided the first evidence for the participation of PepT2 in nutrient absorption. This first description of segment-specific expression and localization points to a complementary role of the different peptide transporters, corresponding to the changes in nutrient availability along the intestine. Both gene expression and absorption activity assays showed that an increase in water salinity shifted the localization of the PepT genes transcription and activity down along the intestinal tract. Additionally, an unexpected pH effect was found on the absorption of small peptides, with increased activity at higher pH levels. This work emphasizes the relationships between different functions of the fish intestine and how they are affected by environmental conditions.
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Affiliation(s)
- Pazit Con
- Agricultural Research Organization, Institute of Animal ScienceRishon Letziyon, Israel; Department of Animal Sciences, Faculty of Agriculture, Food and Environment, The Hebrew University of JerusalemRehovot, Israel
| | - Tali Nitzan
- Agricultural Research Organization, Institute of Animal Science Rishon Letziyon, Israel
| | - Avner Cnaani
- Agricultural Research Organization, Institute of Animal Science Rishon Letziyon, Israel
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Verri T, Barca A, Pisani P, Piccinni B, Storelli C, Romano A. Di- and tripeptide transport in vertebrates: the contribution of teleost fish models. J Comp Physiol B 2017; 187:395-462. [PMID: 27803975 DOI: 10.1007/s00360-016-1044-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 02/06/2023]
Abstract
Solute Carrier 15 (SLC15) family, alias H+-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their role in the cellular uptake of di- and tripeptides (di/tripeptides) and peptide-like molecules. Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from dietary protein digestion, while SLC15A2 (PEPT2) mainly allows renal tubular reabsorption of di/tripeptides from ultrafiltration, SLC15A3 (PHT2) and SLC15A4 (PHT1) possibly interact with di/tripeptides and histidine in certain immune cells, and SLC15A5 has unknown function. Our understanding of this family in vertebrates has steadily increased, also due to the surge of genomic-to-functional information from 'non-conventional' animal models, livestock, poultry, and aquaculture fish species. Here, we review the literature on the SLC15 transporters in teleost fish with emphasis on SLC15A1 (PEPT1), one of the solute carriers better studied amongst teleost fish because of its relevance in animal nutrition. We report on the operativity of the transporter, the molecular diversity, and multiplicity of structural-functional solutions of the teleost fish orthologs with respect to higher vertebrates, its relevance at the intersection of the alimentary and osmoregulative functions of the gut, its response under various physiological states and dietary solicitations, and its possible involvement in examples of total body plasticity, such as growth and compensatory growth. By a comparative approach, we also review the few studies in teleost fish on SLC15A2 (PEPT2), SLC15A4 (PHT1), and SLC15A3 (PHT2). By representing the contribution of teleost fish to the knowledge of the physiology of di/tripeptide transport and transporters, we aim to fill the gap between higher and lower vertebrates.
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