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Hervé Tostivint - One of the best experts on this subject based on the ideXlab platform.
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Data_Sheet_2_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.PDF
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Table_4_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.DOCX
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Data_Sheet_7_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.DOCX
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives
Frontiers in Neuroscience, 2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Daniela Pérez Sirkin, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Image_1_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.TIFF
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
Corey J A Bradshaw - One of the best experts on this subject based on the ideXlab platform.
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to go or not to go with the flow environmental influences on Whale Shark movement patterns
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Jai C Sleeman, Mark G Meekan, Stephen G Wilson, Jeffrey J Polovina, John D Stevens, Guy S Boggs, Corey J A BradshawAbstract:Seven Whale Sharks were tracked using satellite-linked tags from Ningaloo Reef, off northern Western Australia, following tagging in April and June 2002 and April–May 2005. We investigated how the movements of those Whale Shark tracks were influenced by geostrophic surface currents during sequential one-week periods by using a passive diffusion model parameterised with observed starting locations of the Sharks and weekly maps of surface current velocity and direction (derived from altimetry). We compared the outputs from the passive diffusion model and maps of chlorophyll-a concentration (SeaWiFs/MODIS) and with the actual tracks of the Sharks using GIS and generalized linear mixed-effects models (GLMM). The GLMM indicated very little support for passive diffusion with sea-surface ocean currents influencing Whale Shark distributions in the north eastern Indian Ocean. Moreover, the Sharks' movements correlated only weakly with the spatial distribution of sea-surface chlorophyll-a concentrations. The seven Whale Sharks had average swimming speeds comparable with those recorded in other satellite tracking studies of this species. Swimming speeds of the seven Sharks were similar to those reported in previous studies and up to three times greater than the maximum sea-surface current velocities that the Sharks encountered while traversing into lower southerly latitudes (moving northward towards the equator). Our results indicate that Whale Sharks departing from Ningaloo travel actively and independently of near-surface currents where they spend most of their time despite additional metabolic costs of this behaviour.
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oceanographic and atmospheric phenomena influence the abundance of Whale Sharks at ningaloo reef western australia
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Jai C Sleeman, Mark G Meekan, Corey J A Bradshaw, Ben Fitzpatrick, Craig Steinberg, R AncelAbstract:Seasonal observations of Whale Shark abundance recorded by ecotourist operators at Ningaloo Reef, Western Australia from 1999 to 2004 were compared with weekly regional and global oceanographic and atmospheric variables, including average sea surface temperatures, along-shelf wind shear, sea level and the Southern Oscillation Index (SOI). Estimates of these physical variables were derived from either ground-based data or from remote sensing instruments. A generalised linear mixed-effects modelling (GLMM) approach with random sampling and model simulation was used to determine the relationships between the number of Whale Sharks and all model variants of the environmental parameters, using information-theoretic weights of evidence to rank models. SOI and wind shear had the most support for explaining the deviance in weekly Whale Shark abundance at Ningaloo Reef during a season. The SOI and wind shear variables positively influenced Whale Shark abundance such that more Sharks were sighted when the Southern Oscillation was stronger and along-shelf winds were increasingly prevalent. This may reflect changes in the strength of oceanographic processes such as the Leeuwin Current (in response to the Southern Oscillation) and wind/current driven upwelling which may affect the abundance of Whale Sharks transported to the region and/or the availability of their prey by driving productivity changes.
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aerial survey as a tool to estimate Whale Shark abundance trends
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Mark G Meekan, Corey J A Bradshaw, David Rowat, M A Gore, Ivan R LawlerAbstract:Aerial surveys have been used to estimate population abundance of both terrestrial and marine species; in the marine environment this has largely been used for air-breathing species that spend time regularly at the surface. Whale Sharks spend a large proportion of their time close to the surface and so are amenable to aerial survey techniques. This study presents the results of six years of synoptic aerial belt-surveys done nearly daily during the peak Whale Shark season around the island of Mahe, Seychelles. A total of 580 survey flights were flown providing 699.7 hours of survey record. A seasonal peak of Shark sightings per hour was recorded in September or October in most years with the maximum on a single survey of 28.4 h- 1 in October 2006. The aerial survey data were used to generate an estimate of relative population abundance indicating that highest mean annual relative population estimate was also in 2006, with an estimate of 38, while the lowest mean estimate was 11 in 2004. These estimates were then compared to weekly capture-mark-recapture estimates of abundance based on unique individual identification data. The results indicate that the use of aerial survey data alone may give an acceptable indication of instantaneous relative population abundance but further refinement is necessary to estimate absolute regional abundance.
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decline in Whale Shark size and abundance at ningaloo reef over the past decade the world s largest fish is getting smaller
Biological Conservation, 2008Co-Authors: Ben Fitzpatrick, Corey J A Bradshaw, Craig C Steinberg, Barry W Brook, Mark G MeekanAbstract:Over-exploitation of Whale Sharks threatens the future of these wide-ranging pelagic fish. A long-term continuous record (4436 sightings) from a large aggregation (300–500 resident individuals) of Whale Sharks at Ningaloo Reef, Western Australia shows that mean Shark length declined linearly by nearly 2.0 m and relative abundance measured from ecotourism sightings (corrected for variation in search effort and environmental stochasticity) has fallen by approximately 40% over the last decade. This population-level result confirms previous predictions of population decline based on projection models parameterised using mark-recapture estimates of survival. The majority of these changes are driven by reductions in the number of large individuals in the population. Phenomenological time series models support a deterministic (extrinsic) decline in large females, although there was some evidence for density dependence in large males. These reductions have occurred despite the total protection of Whale Sharks in Australian waters. As this species is highly migratory, the rapid change in population composition over a decade (<1 Whale Shark generation) supports the hypothesis of unsustainable mortality in other parts of their range (e.g., overfishing), rather than the alternative of long-term abiotic or biotic shifts in the environment. As such, effective conservation of Whale Sharks will require international protection, and collaborative tagging studies to identify and monitor migratory pathways.
Anne-laure Gaillard - One of the best experts on this subject based on the ideXlab platform.
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Data_Sheet_2_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.PDF
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Table_4_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.DOCX
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Data_Sheet_7_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.DOCX
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives
Frontiers in Neuroscience, 2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Daniela Pérez Sirkin, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
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Image_1_Characterization of Gonadotropin-Releasing Hormone (GnRH) Genes From Cartilaginous Fish: Evolutionary Perspectives.TIFF
2018Co-Authors: Anne-laure Gaillard, Sylvie Mazan, Byrappa Venkatesh, Boon-hui Tay, Daniela Pérez I. Sirkin, Anne-gaëlle Lafont, Céline De Flori, Paula G. Vissio, Sylvie Dufour, Hervé TostivintAbstract:The neuropeptide gonadotropin-releasing hormone (GnRH) plays an important role in the control of reproductive functions. Vertebrates possess multiple GnRH forms that are classified into three main groups, namely GnRH1, GnRH2, and GnRH3. In order to gain more insights into the GnRH gene family in vertebrates, we sought to identify which paralogs of this family are present in cartilaginous fish. For this purpose, we searched the genomes and/or transcriptomes of three representative species of this group, the small-spotted catShark, Scyliorhinus canicula, the Whale Shark, Rhincodon typus and the elephant Shark Callorhinchus milii. In each species, we report the identification of three GnRH genes. In catShark and Whale Shark, phylogenetic and synteny analysis showed that these three genes correspond to GnRH1, GnRH2, and GnRH3. In both species, GnRH1 was found to encode a novel form of GnRH whose primary structure was determined as follows: QHWSFDLRPG. In elephant Shark, the three genes correspond to GnRH1a and GnRH1b, two copies of the GnRH1 gene, plus GnRH2. 3D structure prediction of the chondrichthyan GnRH-associated peptides (GAPs) revealed that catShark GAP1, GAP2, and elephant Shark GAP2 peptides exhibit a helix-loop-helix (HLH) structure. This structure observed for many osteichthyan GAP1 and GAP2, may convey GAP biological activity. This HLH structure could not be observed for elephant Shark GAP1a and GAP1b. As for all other GAP3 described so far, no typical 3D HLH structure was observed for catShark nor Whale Shark GAP3. RT-PCR analysis revealed that GnRH1, GnRH2, and GnRH3 genes are differentially expressed in the catShark brain. GnRH1 mRNA appeared predominant in the diencephalon while GnRH2 and GnRH3 mRNAs seemed to be most abundant in the mesencephalon and telencephalon, respectively. Taken together, our results show that the GnRH gene repertoire of the vertebrate ancestor was entirely conserved in the chondrichthyan lineage but that the GnRH3 gene was probably lost in holocephali. They also suggest that the three GnRH neuronal systems previously described in the brain of bony vertebrates are also present in cartilaginous fish.
Bastien Mérigot - One of the best experts on this subject based on the ideXlab platform.
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Catch and bycatch captured by tropical tuna purse-seine fishery in Whale and Whale Shark associated sets: comparison with free school and FAD sets
Biodiversity and Conservation, 2019Co-Authors: Lauriane Escalle, Daniel Gaertner, Pierre Chavance, Hilario Murua, Monique Simier, Pedro Jose Pascual-alayón, Frédéric Ménard, Jon Ruiz, Francisco Abascal, Bastien MérigotAbstract:In an ecosystem approach to fisheries management (EAFM) framework of the tuna purse-seine fishery, the assessment of target species, but also that of bycatch species, is essential. In the Atlantic and Indian oceans, purse-seine nets are sometimes set around tuna schools associated with Whale Sharks and baleen Whales, although less frequently than around free-swimming tuna schools or those associated with fish aggregating devices (FAD). However, knowledge on the targeted catch and bycatch in these megafauna associated fishing sets is still relatively limited. Therefore, the aims of this study were to assess species and size composition of the target tuna species, as well as the diversity of bycatch species in Whale and Whale Shark associated sets. Whale associated sets were found to be very similar to free school sets in terms of tuna catch (large yellowfin tuna), bycatch occurrence (presence in half the sets) and species assemblage (alpha and beta diversity). Whale Shark associated sets were intermediate between FAD and free school sets, with tuna catch (skipjack and juvenile yellowfin) closer to FAD than to free school sets. However, the presence of large yellowfin, the bycatch composition (with almost no finfish, abundantly captured in FAD sets) and the species assemblage showed similarity with free school sets. This study highlights the need for an EAFM in the tuna purse-seine fishery by providing knowledge on pelagic multi-specific catches and bycatches.
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Consequences of fishing moratoria on catch and bycatch: the case of tropical tuna purse-seiners and Whale and Whale Shark associated sets
Biodiversity and Conservation, 2016Co-Authors: Lauriane Escalle, Daniel Gaertner, Pierre Chavance, Alicia Delgado De Molina, Javier Ariz, Bastien MérigotAbstract:Time–area regulations have been introduced to manage stocks of tropical tuna, given the increased use of drifting fish aggregation devices (FADs). However, the consequences in terms of changes in fishing strategies and effort reallocation may not always be as expected. For instance, in the eastern Pacific Ocean, previous studies have highlighted that the increase use of FAD-fishing following the demand for tuna caught without dolphin mortality has raised concerns about the bycatch and the capture of juvenile tuna. In the tropical eastern Atlantic and western Indian Oceans, this study aimed to (1) assess, using before–after analysis, the consequences of previous time–area regulations on FAD sets on the fishing effort allocated to megafauna associated sets, and (2) evaluate through Monte Carlo simulations the potential effect of new regulations banning Whale or/and Whale Shark associated sets. Firstly, we showed that previous time–area regulations, which were mainly implemented during seasons with few Whale and Whale Shark associated sets, generally had thus little effect on the number of megafauna associated sets. Secondly, some simulations, particularly when both Whale and Whale Shark associated sets were banned, predicted consequences of changes in fishing strategy. Indeed, these types of ban could lead to an increase in the number of FAD and free school sets but no change in the tuna catch, as well as a slight decrease in bycatch. These results indicate that an ecosystem approach to fisheries, by taking into account megafauna associated sets and bycatch, should thus be adopted when implementing management or conservation measures.
Rachel T. Graham - One of the best experts on this subject based on the ideXlab platform.
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Long-term assessment of Whale Shark population demography and connectivity using photo-identification in the Western Atlantic Ocean - Fig 3
2017Co-Authors: Jennifer A. Mckinney, Simon J Pierce, Jason Holmberg, Eric R. Hoffmayer, Rachel T. Graham, William B. Driggers, Rafael De La Parra-venegas, Beatriz E. Galván-pastoriza, Steve Fox, Alistair Dm DoveAbstract:Monthly distribution of Whale Shark encounters in a) Honduras, b) Belize, c) Mexico, and d) US waters.
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Whale Shark photo-identification records for Western Central Atlantic Ocean from 1999–2015 with details of new records and resightings from previous years.
2017Co-Authors: Jennifer A. Mckinney, Simon J Pierce, Jason Holmberg, Eric R. Hoffmayer, Rachel T. Graham, William B. Driggers, Rafael De La Parra-venegas, Beatriz E. Galván-pastoriza, Steve Fox, Alistair Dm DoveAbstract:Whale Shark photo-identification records for Western Central Atlantic Ocean from 1999–2015 with details of new records and resightings from previous years.
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Probability of resighting an individual Whale Shark over time (LIR; mean +- S.D.) within the Western Central Atlantic compared to the best fitting model (dark line).
2017Co-Authors: Jennifer A. Mckinney, Simon J Pierce, Jason Holmberg, Eric R. Hoffmayer, Rachel T. Graham, William B. Driggers, Rafael De La Parra-venegas, Beatriz E. Galván-pastoriza, Steve Fox, Alistair Dm DoveAbstract:Probability of resighting an individual Whale Shark over time (LIR; mean +- S.D.) within the Western Central Atlantic compared to the best fitting model (dark line).
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Probability of resighting an individual Whale Shark over time (LIR; mean ± S.D.) within the same location (green circle) or a different location (red asterisk) in the Western Central Atlantic compared to the best fitting model (dark line).
2017Co-Authors: Jennifer A. Mckinney, Simon J Pierce, Jason Holmberg, Eric R. Hoffmayer, Rachel T. Graham, William B. Driggers, Rafael De La Parra-venegas, Beatriz E. Galván-pastoriza, Steve Fox, Alistair Dm DoveAbstract:Probability of resighting an individual Whale Shark over time (LIR; mean ± S.D.) within the same location (green circle) or a different location (red asterisk) in the Western Central Atlantic compared to the best fitting model (dark line).
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Spatial distribution of sightings data collected through Wildbook for Whale Sharks in the Western Central Atlantic Ocean during 1999–2015.
2017Co-Authors: Jennifer A. Mckinney, Simon J Pierce, Jason Holmberg, Eric R. Hoffmayer, Rachel T. Graham, William B. Driggers, Rafael De La Parra-venegas, Beatriz E. Galván-pastoriza, Steve Fox, Alistair Dm DoveAbstract:Movements between Whale Shark sightings within the Gulf of Mexico and Caribbean, including Honduras (HN), Belize (BZ), Mexico (MX), United States of America (US), and the greater Caribbean region (CRB) based on photo-identification data.
