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Ito-Harashima S, Tsubouchi Y, Takada E, Kawanishi M, Yagi T. Development of a yeast reporter gene assay to detect ligands of freshwater cladoceran Daphnia magna ultraspiracle, a homolog of vertebrate retinoid X receptors. J Appl Toxicol 2023; 43:1447-1461. [PMID: 37078133 DOI: 10.1002/jat.4476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 04/16/2023] [Accepted: 04/17/2023] [Indexed: 04/21/2023]
Abstract
Endocrine-disrupting chemicals (EDCs) often affect homeostatic regulation in living organisms by directly acting on nuclear receptors (NRs). Retinoid X receptors (RXRs), the most highly conserved members of the NR superfamily during evolution, function as partners to form heterodimers with other NRs, such as retinoic acid, thyroid hormone, and vitamin D3 receptors. RXRs also homodimerize and induce the expression of target genes upon binding with their natural ligand, 9-cis-retinoic acid (9cRA), and typical EDCs organotin compounds, such as tributyltin and triphenyltin. In the present study, we established a new yeast reporter gene assay (RGA) to detect the ligands of freshwater cladoceran Daphnia magna ultraspiracle (Dapma-USP), a homolog of vertebrate RXRs. D. magna has been used as a representative crustacean species for aquatic EDC assessments in the Organization for Economic Corporation and Development test guidelines. Dapma-USP was expressed along with the Drosophila melanogaster steroid receptor coactivator Taiman in yeast cells carrying the lacZ reporter plasmid. The RGA for detecting agonist activity of organotins and o-butylphenol was improved by use of mutant yeast strains lacking genes encoding cell wall mannoproteins and/or plasma membrane drug efflux pumps as hosts. We also showed that a number of other human RXR ligands, phenol and bisphenol A derivatives, and terpenoid compounds such as 9c-RA exhibited antagonist activity on Dapma-USP. Our newly established yeast-based RGA system is valuable as the first screening tool to detect ligand substances for Dapma-USP and for evaluating the evolutionary divergence of the ligand responses of RXR homologs between humans and D. magna.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Applied Biological Chemistry, Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Japan
| | - Yumiko Tsubouchi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Eiji Takada
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Masanobu Kawanishi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai, Japan
| | - Takashi Yagi
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai, Japan
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Wyngaard GA, Skern-Mauritzen R, Malde K, Prendergast R, Peruzzi S. The salmon louse genome may be much larger than sequencing suggests. Sci Rep 2022; 12:6616. [PMID: 35459797 PMCID: PMC9033869 DOI: 10.1038/s41598-022-10585-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 04/08/2022] [Indexed: 12/30/2022] Open
Abstract
The genome size of organisms impacts their evolution and biology and is often assumed to be characteristic of a species. Here we present the first published estimates of genome size of the ecologically and economically important ectoparasite, Lepeophtheirus salmonis (Copepoda, Caligidae). Four independent L. salmonis genome assemblies of the North Atlantic subspecies Lepeophtheirus salmonis salmonis, including two chromosome level assemblies, yield assemblies ranging from 665 to 790 Mbps. These genome assemblies are congruent in their findings, and appear very complete with Benchmarking Universal Single-Copy Orthologs analyses finding > 92% of expected genes and transcriptome datasets routinely mapping > 90% of reads. However, two cytometric techniques, flow cytometry and Feulgen image analysis densitometry, yield measurements of 1.3-1.6 Gb in the haploid genome. Interestingly, earlier cytometric measurements reported genome sizes of 939 and 567 Mbps in L. salmonis salmonis samples from Bay of Fundy and Norway, respectively. Available data thus suggest that the genome sizes of salmon lice are variable. Current understanding of eukaryotic genome dynamics suggests that the most likely explanation for such variability involves repetitive DNA, which for L. salmonis makes up ≈ 60% of the genome assemblies.
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Affiliation(s)
- Grace A Wyngaard
- Department of Biology, James Madison University, Harrisonburg, VA, USA
| | | | - Ketil Malde
- Institute of Marine Research, Bergen, Norway
- Department of Informatics, University of Bergen, Bergen, Norway
| | | | - Stefano Peruzzi
- Department of Arctic Marine Biology, UiT-the Arctic University of Norway, Tromsø, Norway.
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Zhou Z, Eichner C, Nilsen F, Jonassen I, Dondrup M. A novel approach to co-expression network analysis identifies modules and genes relevant for moulting and development in the Atlantic salmon louse (Lepeophtheirus salmonis). BMC Genomics 2021; 22:832. [PMID: 34789144 PMCID: PMC8600823 DOI: 10.1186/s12864-021-08054-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/04/2021] [Indexed: 11/25/2022] Open
Abstract
Background The salmon louse (Lepeophtheirus salmonis) is an obligate ectoparasitic copepod living on Atlantic salmon and other salmonids in the marine environment. Salmon lice cause a number of environmental problems and lead to large economical losses in aquaculture every year. In order to develop novel parasite control strategies, a better understanding of the mechanisms of moulting and development of the salmon louse at the transcriptional level is required. Methods Three weighted gene co-expression networks were constructed based on the pairwise correlations of salmon louse gene expression profiles at different life stages. Network-based approaches and gene annotation information were applied to identify genes that might be important for the moulting and development of the salmon louse. RNA interference was performed for validation. Regulatory impact factors were calculated for all the transcription factor genes by examining the changes in co-expression patterns between transcription factor genes and deferentially expressed genes in middle stages and moulting stages. Results Eight gene modules were predicted as important, and 10 genes from six of the eight modules have been found to show observable phenotypes in RNA interference experiments. We knocked down five hub genes from three modules and observed phenotypic consequences in all experiments. In the infection trial, no copepodids with a RAB1A-like gene knocked down were found on fish, while control samples developed to chalimus-1 larvae. Also, a FOXO-like transcription factor obtained highest scores in the regulatory impact factor calculation. Conclusions We propose a gene co-expression network-based approach to identify genes playing an important role in the moulting and development of salmon louse. The RNA interference experiments confirm the effectiveness of our approach and demonstrated the indispensable role of a RAB1A-like gene in the development of the salmon louse. We propose that our approach could be generalized to identify important genes associated with a phenotype of interest in other organisms. Supplementary Information The online version contains supplementary material available at (10.1186/s12864-021-08054-7).
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Affiliation(s)
- Zhaoran Zhou
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Inge Jonassen
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Michael Dondrup
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway.
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The FTZ-F1 gene encodes two functionally distinct nuclear receptor isoforms in the ectoparasitic copepod salmon louse (Lepeophtheirus salmonis). PLoS One 2021; 16:e0251575. [PMID: 34014986 PMCID: PMC8136749 DOI: 10.1371/journal.pone.0251575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 04/29/2021] [Indexed: 01/21/2023] Open
Abstract
The salmon louse, Lepeophtheirus salmonis, is an ectoparasitic crustacean that annually inflicts substantial losses to the aquaculture industry in the northern hemisphere and poses a threat to the wild populations of salmonids. The salmon louse life cycle consists of eight developmental stages each separated by a molt. Fushi Tarazu Factor-1 (FTZ-F1) is an ecdysteroid-regulated gene that encodes a member of the NR5A family of nuclear receptors that is shown to play a crucial regulatory role in molting in insects and nematodes. Characterization of an FTZ-F1 orthologue in the salmon louse gave two isoforms named αFTZ-F1 and βFTZ-F1, which are identical except for the presence of a unique N-terminal domain (A/B domain). A comparison suggest conservation of the FTZ-F1 gene structure among ecdysozoans, with the exception of nematodes, to produce isoforms with unique N-terminal domains through alternative transcription start and splicing. The two isoforms of the salmon louse FTZ-F1 were expressed in different amounts in the same tissues and showed a distinct cyclical expression pattern through the molting cycle with βFTZ-F1 being the highest expressed isoform. While RNA interference knockdown of βFTZ-F1 in nauplius larvae and in pre-adult males lead to molting arrest, knockdown of βFTZ-F1 in pre-adult II female lice caused disruption of oocyte maturation at the vitellogenic stage. No apparent phenotype could be observed in αFTZ-F1 knockdown larvae, or in their development to adults, and no genes were found to be differentially expressed in the nauplii larvae following αFTZ-F1 knockdown. βFTZ-F1 knockdown in nauplii larvae caused both down and upregulation of genes associated with proteolysis and chitin binding and affected a large number of genes which are in normal salmon louse development expressed in a cyclical pattern. This is the first description of FTZ-F1 gene function in copepod crustaceans and provides a foundation to expand the understanding of the molecular mechanisms of molting in the salmon louse and other copepods.
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Kluebsoongnoen J, Panyim S, Sarnowski TJ, Udomkit A. Retinoid X receptor modulates vitellogenin gene expression in black tiger shrimp, Penaeus monodon. Comp Biochem Physiol A Mol Integr Physiol 2020; 254:110877. [PMID: 33352261 DOI: 10.1016/j.cbpa.2020.110877] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/17/2020] [Accepted: 12/17/2020] [Indexed: 11/28/2022]
Abstract
Effective inducing of ovarian maturation in female shrimp broodstock is important for successful breeding programs. Vitellogenesis is a biochemical process during which a yolk protein precursor vitellogenin (Vg) is synthesized and thus, can be used to indicate ovarian maturation stage. In this study, transcriptional regulation of Vg synthesis in the black tiger shrimp, Penaeus monodon was investigated. Genome walking on 5' upstream sequence of Vg gene revealed several putative binding sites of lipophilic retinoic acid response elements (RARE), and nuclear hormone responsive elements. Deletion of RARE significantly reduced the promoter activity to drive the expression of luciferase reporter gene in Sf-9 cells. To validate the trans-factor that potentially controls Vg expression through RARE, a cDNA encoding retinoid X receptor (PmRXR), one of the RARE-bound transcription factors was cloned from P. monodon's ovary. PmRXR expression was detected in various shrimp tissues, and was up-regulated during ovary development in a similar way to Vg expression. The DNA-binding domain of PmRXR protein showed specific binding to RARE-containing region on Vg 5' upstream sequence as determined by Electrophoretic Mobility Shift Assay (EMSA). Furthermore, dsRNA-mediated PmRXR silencing in previtellogenic and vitellogenic shrimp revealed that suppression of PmRXR could reduce Vg transcript in both stages. Taken together, the results presented in this study indicate that RXR is possibly an activator protein that modulates Vg expression in shrimp ovary through the binding to RARE.
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Affiliation(s)
- Jakkapong Kluebsoongnoen
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom 73170, Thailand
| | - Sakol Panyim
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom 73170, Thailand; Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
| | - Tomasz J Sarnowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Apinunt Udomkit
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom 73170, Thailand.
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Identification of critical enzymes in the salmon louse chitin synthesis pathway as revealed by RNA interference-mediated abrogation of infectivity. Int J Parasitol 2020; 50:873-889. [PMID: 32745476 DOI: 10.1016/j.ijpara.2020.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/10/2020] [Accepted: 06/18/2020] [Indexed: 12/12/2022]
Abstract
Treatment of infestation by the ectoparasite Lepeophtheirus salmonis relies on a small number of chemotherapeutant treatments that currently meet with limited success. Drugs targeting chitin synthesis have been largely successful against terrestrial parasites where the pathway is well characterised. However, a comparable approach against salmon lice has been, until recently, less successful, likely due to a poor understanding of the chitin synthesis pathway. Post-transcriptional silencing of genes by RNA interference (RNAi) is a powerful method for evaluation of protein function in non-model organisms and has been successfully applied to the salmon louse. In the present study, putative genes coding for enzymes involved in L. salmonis chitin synthesis were characterised after knockdown by RNAi. Nauplii I stage L. salmonis were exposed to double-stranded (ds) RNA specific for several putative non-redundant points in the pathway: glutamine: fructose-6-phosphate aminotransferase (LsGFAT), UDP-N-acetylglucosamine pyrophosphorylase (LsUAP), N-acetylglucosamine phosphate mutase (LsAGM), chitin synthase 1 (LsCHS1), and chitin synthase 2 (LsCHS2). Additionally, we targeted three putative chitin deacetylases (LsCDA4557, 5169 and 5956) by knockdown. Successful knockdown was determined after moulting to the copepodite stage by real-time quantitative PCR (RT-qPCR), while infectivity potential (the number of attached chalimus II compared with the initial number of larvae in the system) was measured after exposure to Atlantic salmon and subsequent development on their host. Compared with controls, infectivity potential was not compromised in dsAGM, dsCHS2, dsCDA4557, or dsCDA5169 groups. In contrast, there was a significant effect in the dsUAP-treated group. However, of most interest was the treatment with dsGFAT, dsCHS1, dsCHS1+2, and dsCDA5956, which resulted in complete abrogation of infectivity, despite apparent compensatory mechanisms in the chitin synthesis pathway as detected by qPCR. There appeared to be a common phenotypic effect in these groups, characterised by significant aberrations in appendage morphology and an inability to swim. Ultrastructurally, dsGFAT showed a significantly distorted procuticle without distinct exo/endocuticle and intermittent electron dense (i.e. chitin) inclusions, and together with dsUAP and dsCHS1, indicated delayed entry to the pre-moult phase.
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Tarrant AM, Nilsson B, Hansen BW. Molecular physiology of copepods - from biomarkers to transcriptomes and back again. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2019; 30:230-247. [DOI: 10.1016/j.cbd.2019.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/14/2019] [Accepted: 03/16/2019] [Indexed: 12/31/2022]
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Poley JD, Braden LM, Messmer AM, Igboeli OO, Whyte SK, Macdonald A, Rodriguez J, Gameiro M, Rufener L, Bouvier J, Wadowska DW, Koop BF, Hosking BC, Fast MD. High level efficacy of lufenuron against sea lice (Lepeophtheirus salmonis) linked to rapid impact on moulting processes. Int J Parasitol Drugs Drug Resist 2018; 8:174-188. [PMID: 29627513 PMCID: PMC6039351 DOI: 10.1016/j.ijpddr.2018.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/26/2018] [Accepted: 02/28/2018] [Indexed: 11/29/2022]
Abstract
Drug resistance in the salmon louse Lepeophtheirus salmonis is a global issue for Atlantic salmon aquaculture. Multiple resistance has been described across most available compound classes with the exception of the benzoylureas. To target this gap in effective management of L. salmonis and other species of sea lice (e.g. Caligus spp.), Elanco Animal Health is developing an in-feed treatment containing lufenuron (a benzoylurea) to be administered prior to seawater transfer of salmon smolts and to provide long-term protection of salmon against sea lice infestations. Benzoylureas disrupt chitin synthesis, formation, and deposition during all moulting events. However, the mechanism(s) of action are not yet fully understood and most research completed to date has focused on insects. We exposed the first parasitic stage of L. salmonis to 700 ppb lufenuron for three hours and observed over 90% reduction in survival to the chalimus II life stage on the host, as compared to vehicle controls. This agrees with a follow up in vivo administration study on the host, which showed >95% reduction by the chalimus I stage. Transcriptomic responses of salmon lice exposed to lufenuron included genes related to moulting, epithelial differentiation, solute transport, and general developmental processes. Global metabolite profiles also suggest that membrane stability and fluidity is impacted in treated lice. These molecular signals are likely the underpinnings of an abnormal moulting process and cuticle formation observed ultrastructurally using transmission electron microscopy. Treated nauplii-staged lice exhibited multiple abnormalities in the integument, suggesting that the coordinated assembly of the epi- and procuticle is impaired. In all cases, treatment with lufenuron had rapid impacts on L. salmonis development. We describe multiple experiments to characterize the efficacy of lufenuron on eggs, larvae, and parasitic stages of L. salmonis, and provide the most comprehensive assessment of the physiological responses of a marine arthropod to a benzoylurea chemical.
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Affiliation(s)
- Jordan D Poley
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Laura M Braden
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Amber M Messmer
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Okechukwu O Igboeli
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Shona K Whyte
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Alicia Macdonald
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Jose Rodriguez
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Marta Gameiro
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Lucien Rufener
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Jacques Bouvier
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Dorota W Wadowska
- Electron Microscopy Laboratory, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PEI, C1A 4P3, Canada.
| | - Ben F Koop
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Barry C Hosking
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Mark D Fast
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
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Farlora R, Valdebenito-Aguayo F, Valenzuela-Muñoz V, Gallardo-Escárate C. Hydrogen peroxide treatment modulates the transcription of sex-related genes in the sea lice Caligus rogercresseyi. JOURNAL OF FISH DISEASES 2018; 41:921-926. [PMID: 28984365 DOI: 10.1111/jfd.12700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 06/07/2023]
Affiliation(s)
- R Farlora
- Laboratorio de Biotecnología Acuática y Genómica Reproductiva/Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - F Valdebenito-Aguayo
- Laboratory of Biotechnology and Aquatic Genomics, Universidad de Concepción, Concepción, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile
| | - V Valenzuela-Muñoz
- Laboratory of Biotechnology and Aquatic Genomics, Universidad de Concepción, Concepción, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile
| | - C Gallardo-Escárate
- Laboratory of Biotechnology and Aquatic Genomics, Universidad de Concepción, Concepción, Chile
- Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile
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Eichner C, Dondrup M, Nilsen F. RNA sequencing reveals distinct gene expression patterns during the development of parasitic larval stages of the salmon louse (Lepeophtheirus salmonis). JOURNAL OF FISH DISEASES 2018; 41:1005-1029. [PMID: 29368347 DOI: 10.1111/jfd.12770] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Abstract
The salmon louse (Lepeophtheirus salmonis), an ectoparasitic copepod on salmonids, has become a major threat for the aquaculture industry. In search for new drugs and vaccines, transcriptome analysis is increasingly used to find differently regulated genes and pathways in response to treatment. However, the underlying gene expression changes going along with developmental processes could confound such analyses. The life cycle of L. salmonis consists of eight stages divided by moults. The developmental rate of salmon lice on the host is not uniform. Individual- and sex-related differences are found leading to individuals of unlike developmental status at same sampling time point after infection. In this study, we analyse L. salmonis from a time series by RNA sequencing applying a method of separating individuals of different instar age independent of sampling time point. Lice of four stages divided into up to four age groups within the stage were analysed in triplicate (total of 66 samples). Gene expression analysis shows that the method for sorting individuals was successful. Many genes show cyclic expression patterns over the moulting cycles. Overall gene expression differs more between lice of different age within the same stage than between lice of different stage but same instar age.
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Affiliation(s)
- C Eichner
- Sea Lice Research Centre, Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - M Dondrup
- Sea Lice Research Centre, Department of Informatics, University of Bergen, Bergen, Norway
| | - F Nilsen
- Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
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11
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Sandlund L, Kongshaug H, Nilsen F, Dalvin S. Molecular characterization and functional analysis of components of the TOR pathway of the salmon louse, Lepeophtheirus salmonis (Krøyer, 1838). Exp Parasitol 2018; 188:83-92. [PMID: 29625096 DOI: 10.1016/j.exppara.2018.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/16/2018] [Accepted: 04/02/2018] [Indexed: 11/27/2022]
Abstract
The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting salmonid fishes in the northern hemisphere. At present, salmon lice infections are the most severe disease problem in the salmon farming industry causing significant economic losses. Due to development of resistance towards available chemotherapeutants, it is clear that new chemotherapeutants or non-chemical control methods are essential to manage the parasite in the future. The TOR signaling pathway is present in all metazoans and is a major regulator of cellular activity according to nutrient availability. In this study, we identified the TOR pathway genes in salmon louse; LsTSC1, LsTSC2, LsRheb, LsTOR, LsRaptor and LsRictor. RNA interference mediated gene silencing was performed to elucidate the functional role of each member of the pathway. Our results show that interference of the TOR signaling pathway either directly or indirectly inhibits many biological processes including egg maturation. In addition, the effect of gene knock-down results in more comprehensive physiological defects when targeting TORC1 and the upstream regulator Rheb. This is the first report on the TOR pathway in the salmon louse and that our research contributes to the basic knowledge of the parasite that could lead to development of novel treatment methods.
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Affiliation(s)
- Liv Sandlund
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway
| | - Heidi Kongshaug
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Frank Nilsen
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Sussie Dalvin
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway.
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12
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Sandlund L, Kongshaug H, Horsberg TE, Male R, Nilsen F, Dalvin S. Identification and characterisation of the ecdysone biosynthetic genes neverland, disembodied and shade in the salmon louse Lepeophtheirus salmonis (Copepoda, Caligidae). PLoS One 2018; 13:e0191995. [PMID: 29401467 PMCID: PMC5798790 DOI: 10.1371/journal.pone.0191995] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 01/14/2018] [Indexed: 11/19/2022] Open
Abstract
The salmon louse is a marine ectoparasitic copepod on salmonid fishes. Its lifecycle consists of eight developmental stages, each separated by a molt. In crustaceans and insects, molting and reproduction is controlled by circulating steroid hormones such as 20-hydroxyecdysone. Steroid hormones are synthesized from cholesterol through catalytic reactions involving a 7,8-dehydrogenase Neverland and several cytochrome P450 genes collectively called the Halloween genes. In this study, we have isolated and identified orthologs of neverland, disembodied and shade in the salmon louse (Lepeophtheirus salmonis) genome. Tissue-specific expression analysis show that the genes are expressed in intestine and reproductive tissue. In addition, levels of the steroid hormones ecdysone, 20-hydroxyecdysone and ponasterone A were measured during the reproductive stage of adult females and in early life stages.
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Affiliation(s)
- Liv Sandlund
- Sea Lice Research Centre, Department of Biological sciences, University of Bergen, Bergen, Norway
- Sea Lice Research Centre, Institute of Marine Research, Bergen, Norway
| | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biological sciences, University of Bergen, Bergen, Norway
| | - Tor Einar Horsberg
- Sea Lice Research Centre, Norwegian University of Life Sciences, Oslo, Norway
| | - Rune Male
- Sea Lice Research Centre, Department of Biological sciences, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biological sciences, University of Bergen, Bergen, Norway
| | - Sussie Dalvin
- Sea Lice Research Centre, Institute of Marine Research, Bergen, Norway
- * E-mail:
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13
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Sandlund L, Nilsen F, Male R, Dalvin S. The ecdysone receptor (EcR) is a major regulator of tissue development and growth in the marine salmonid ectoparasite, Lepeophtheirus salmonis (Copepoda, Caligidae). Mol Biochem Parasitol 2016; 208:65-73. [DOI: 10.1016/j.molbiopara.2016.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 01/23/2023]
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14
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Gong J, Huang C, Shu L, Bao C, Huang H, Ye H, Zeng C, Li S. The retinoid X receptor from mud crab: new insights into its roles in ovarian development and related signaling pathway. Sci Rep 2016; 6:23654. [PMID: 27009370 PMCID: PMC4806290 DOI: 10.1038/srep23654] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/08/2016] [Indexed: 11/09/2022] Open
Abstract
In arthropods, retinoid X receptor (RXR) is a highly conserved nuclear hormone receptor. By forming a heterodimeric complex with the ecdysone receptor (EcR), RXR is known to be vital importance for various physiological processes. However, in comparison to EcR, the RXR signaling pathway and its roles in crustacean reproduction are poorly understood. In the present study, the RXR mRNA was detected in the ovarian follicular cells of mud crab Scylla paramamosain (SpRXR) and during ovarian maturation, its expression level was found to increase significantly. In vitro experiment showed that both SpRXR and vitellogenin (SpVg) mRNA in the ovarian explants were significantly induced by 20-hydroxyecdysone (20E) but not methyl farnesoate (MF). However, differing from the in vitro experiment, injection of MF in in vivo experiment significantly stimulated the expressions of SpRXR and SpVg in female crabs at early vitellogenic stage, but the ecdysone and insect juvenile hormone (JH) signaling pathway genes were not induced. The results together suggest that both MF and SpRXR play significant roles in regulating the expression of SpVg and ovarian development of S. paramamosain through their own specific signaling pathway rather than sharing with the ecdysone or the insect JH.
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Affiliation(s)
- Jie Gong
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
- School of Life Sciences, Nantong University, Nantong 226007, China
| | - Chencui Huang
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Ling Shu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Chenchang Bao
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Huiyang Huang
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Haihui Ye
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
- Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen 361102, China
| | - Chaoshu Zeng
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Shaojing Li
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
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