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Clothilde Heude-berthelin - One of the best experts on this subject based on the ideXlab platform.
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Morphological and molecular criteria allow the identification of putative germ stem cells in a lophotrochozoan, the Pacific oyster Crassostrea gigas
Histochemistry and Cell Biology, 2019Co-Authors: Maëva Cherif-feildel, Kristell Kellner, Béatrice Adeline, Didier Goux, Nicolas Elie, Christophe Lelong, Clothilde Heude-berthelinAbstract:While our knowledge of bivalve Gametogenesis recently progressed, data on early stages of Gametogenesis remain to be developed, especially when dealing with germinal stem cells (GSC) and their niche in these organisms. Here, we wish to develop a strategy to identify putative GSC in Pacific oyster Crassostrea gigas based on morphological criteria combined with vasa marker expression. A histological quantitative approach, based on stereology, allowed us to identify two types of early germ cells in the germinal epithelium, one presenting round nuclei and the other irregular ones. Both early germ cell types present slightly condensed chromatin in nucleus, are vasa-positive and the Oyvlg (oyster vasa-like gene) expression in these cells is recorded throughout the whole Gametogenesis process. The microenvironment of an early germ cell in oyster includes an associated somatic cell presenting an immunolabeling for BMP2/4 and a close myoid cell. In agreement with the GSC characteristics in other species, we postulate that putative germ stem cells in C. gigas correspond to the early germ cell type with irregular nucleus shape; those early germ cells with a round nucleus may consist in progenitors.
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Impact of energy storage strategies on Gametogenesis and reproductive effort in diploid and triploid Pacific oysters Crassostrea gigas — Involvement of insulin signaling
Aquaculture, 2013Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, J.l. Blin, Béatrice Adeline, M. Mathieu, K. KellnerAbstract:Gametogenesis of the Pacific oyster Crassostrea gigas follows an annual cycle. In this work, we used contrasting dietary conditions (fed and unfed) for a preconditioning treatment in order to impact glycogen storage supporting reproductive pathways in diploid and triploid animals before a broodstock conditioning treatment. In diploid oysters, food deprivation during preconditioning led to reduced gonia proliferation as demonstrated by lower PCNA (Proliferating Cell Nuclear Antigen) expression and subsequently, the reproductive effort was significantly reduced. For triploid animals exhibiting arrested Gametogenesis, dietary conditions impacted the ratio of α (animals with unlocked Gametogenesis) and β (animals with locked Gametogenesis). Thermal stress applied to these conditioned animals confirmed the weakness of diploid animals with high stored reserves and intense reproductive effort, versus low reproductive effort. Moreover, only low mortalities were observed for triploid animals whatever the reproductive status. The involvement of the insulin pathway in the regulation of Gametogenesis and storage rebuilding was assessed by measuring an increased expression of CIR (C. gigas insulin related receptor) in unfed oysters.
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Gametogenic stages in triploid oysters Crassostrea gigas: Irregular locking of gonial proliferation and subsequent reproductive effort
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, Michel Mathieu, Kristell KellnerAbstract:Abstract Although triploid oysters Crassostrea gigas have generally been considered to be sterile, Gametogenesis events are sometimes recorded. We aimed to establish a new classification adapted for the description of Gametogenesis in triploid oysters and their comparison with diploid animals. From stage I to stage III, two types of gametogenic pattern were identified: α-pattern, corresponding to animals displaying numerous proliferating gonia (PCNA labelling at stage I), resulting in abundant gametes at stage III and β-pattern, which was associated with locked Gametogenesis (only few mature gametes at sexual maturity) with accumulation of abnormal gonia from stage I to III. The granular aspect of TUNEL labelling in the perinuclear area of stage Iα animals suggests either the occurrence of apoptotic events or the possibility of chromosome number regulation (chromosome extrusion). Reproductive effort was evaluated by quantitative approaches in order to evaluate the possible contribution of triploid oysters to recruitment in the natural environment. For mature α triploid animals, the ratio of gonadal area over total area on histological slide preparations reached almost 50% that of diploid counterparts. Moreover, the gonadal area contained numerous mature germinal cells as in diploids. Future ecological studies should consider the involvement of triploids in spat recruitment in the case of spawning by these animals.
K. Kellner - One of the best experts on this subject based on the ideXlab platform.
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Impact of energy storage strategies on Gametogenesis and reproductive effort in diploid and triploid Pacific oysters Crassostrea gigas — Involvement of insulin signaling
Aquaculture, 2013Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, J.l. Blin, Béatrice Adeline, M. Mathieu, K. KellnerAbstract:Gametogenesis of the Pacific oyster Crassostrea gigas follows an annual cycle. In this work, we used contrasting dietary conditions (fed and unfed) for a preconditioning treatment in order to impact glycogen storage supporting reproductive pathways in diploid and triploid animals before a broodstock conditioning treatment. In diploid oysters, food deprivation during preconditioning led to reduced gonia proliferation as demonstrated by lower PCNA (Proliferating Cell Nuclear Antigen) expression and subsequently, the reproductive effort was significantly reduced. For triploid animals exhibiting arrested Gametogenesis, dietary conditions impacted the ratio of α (animals with unlocked Gametogenesis) and β (animals with locked Gametogenesis). Thermal stress applied to these conditioned animals confirmed the weakness of diploid animals with high stored reserves and intense reproductive effort, versus low reproductive effort. Moreover, only low mortalities were observed for triploid animals whatever the reproductive status. The involvement of the insulin pathway in the regulation of Gametogenesis and storage rebuilding was assessed by measuring an increased expression of CIR (C. gigas insulin related receptor) in unfed oysters.
Aude Jouaux - One of the best experts on this subject based on the ideXlab platform.
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Impact of energy storage strategies on Gametogenesis and reproductive effort in diploid and triploid Pacific oysters Crassostrea gigas — Involvement of insulin signaling
Aquaculture, 2013Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, J.l. Blin, Béatrice Adeline, M. Mathieu, K. KellnerAbstract:Gametogenesis of the Pacific oyster Crassostrea gigas follows an annual cycle. In this work, we used contrasting dietary conditions (fed and unfed) for a preconditioning treatment in order to impact glycogen storage supporting reproductive pathways in diploid and triploid animals before a broodstock conditioning treatment. In diploid oysters, food deprivation during preconditioning led to reduced gonia proliferation as demonstrated by lower PCNA (Proliferating Cell Nuclear Antigen) expression and subsequently, the reproductive effort was significantly reduced. For triploid animals exhibiting arrested Gametogenesis, dietary conditions impacted the ratio of α (animals with unlocked Gametogenesis) and β (animals with locked Gametogenesis). Thermal stress applied to these conditioned animals confirmed the weakness of diploid animals with high stored reserves and intense reproductive effort, versus low reproductive effort. Moreover, only low mortalities were observed for triploid animals whatever the reproductive status. The involvement of the insulin pathway in the regulation of Gametogenesis and storage rebuilding was assessed by measuring an increased expression of CIR (C. gigas insulin related receptor) in unfed oysters.
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Gametogenic stages in triploid oysters Crassostrea gigas: Irregular locking of gonial proliferation and subsequent reproductive effort
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, Michel Mathieu, Kristell KellnerAbstract:Abstract Although triploid oysters Crassostrea gigas have generally been considered to be sterile, Gametogenesis events are sometimes recorded. We aimed to establish a new classification adapted for the description of Gametogenesis in triploid oysters and their comparison with diploid animals. From stage I to stage III, two types of gametogenic pattern were identified: α-pattern, corresponding to animals displaying numerous proliferating gonia (PCNA labelling at stage I), resulting in abundant gametes at stage III and β-pattern, which was associated with locked Gametogenesis (only few mature gametes at sexual maturity) with accumulation of abnormal gonia from stage I to III. The granular aspect of TUNEL labelling in the perinuclear area of stage Iα animals suggests either the occurrence of apoptotic events or the possibility of chromosome number regulation (chromosome extrusion). Reproductive effort was evaluated by quantitative approaches in order to evaluate the possible contribution of triploid oysters to recruitment in the natural environment. For mature α triploid animals, the ratio of gonadal area over total area on histological slide preparations reached almost 50% that of diploid counterparts. Moreover, the gonadal area contained numerous mature germinal cells as in diploids. Future ecological studies should consider the involvement of triploids in spat recruitment in the case of spawning by these animals.
Pierre Boudry - One of the best experts on this subject based on the ideXlab platform.
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Comparative histological study of Gametogenesis in diploid and triploid Pacific oysters (Crassostrea gigas) reared in an estuarine farming site in France during the 2003 heatwave
Aquaculture, 2008Co-Authors: Julien Normand, Marcel Le Pennec, Pierre BoudryAbstract:We compared the temporal dynamics of Gametogenesis in diploid and triploid Pacific oysters (Crassostrea gigas) using histology. Oysters were reared in an estuarine farming site in Brittany over 3 years and their Gametogenesis was monitored over the exceptionally hot summer of 2003. Both diploids and triploids showed active Gametogenesis, but a high proportion of triploids remained at early stages of gonad development. Gametogenesis of triploids was characterized by the simultaneous occurrence of gonias and immature cytes together with mature gametes rather than overall retardation, though some triploids showed complete gonad maturation. Evidence of spawning was seen in both groups, and the quantity of germinal products emitted appeared to be similar in triploids and diploids, though triploids were much heavier than diploids. Our study supports previously reported experimental observations and suggests that gonad development in triploid Pacific oysters can be enhanced when these oysters are reared in the field under unusually warm conditions.
Béatrice Adeline - One of the best experts on this subject based on the ideXlab platform.
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Morphological and molecular criteria allow the identification of putative germ stem cells in a lophotrochozoan, the Pacific oyster Crassostrea gigas
Histochemistry and Cell Biology, 2019Co-Authors: Maëva Cherif-feildel, Kristell Kellner, Béatrice Adeline, Didier Goux, Nicolas Elie, Christophe Lelong, Clothilde Heude-berthelinAbstract:While our knowledge of bivalve Gametogenesis recently progressed, data on early stages of Gametogenesis remain to be developed, especially when dealing with germinal stem cells (GSC) and their niche in these organisms. Here, we wish to develop a strategy to identify putative GSC in Pacific oyster Crassostrea gigas based on morphological criteria combined with vasa marker expression. A histological quantitative approach, based on stereology, allowed us to identify two types of early germ cells in the germinal epithelium, one presenting round nuclei and the other irregular ones. Both early germ cell types present slightly condensed chromatin in nucleus, are vasa-positive and the Oyvlg (oyster vasa-like gene) expression in these cells is recorded throughout the whole Gametogenesis process. The microenvironment of an early germ cell in oyster includes an associated somatic cell presenting an immunolabeling for BMP2/4 and a close myoid cell. In agreement with the GSC characteristics in other species, we postulate that putative germ stem cells in C. gigas correspond to the early germ cell type with irregular nucleus shape; those early germ cells with a round nucleus may consist in progenitors.
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Impact of energy storage strategies on Gametogenesis and reproductive effort in diploid and triploid Pacific oysters Crassostrea gigas — Involvement of insulin signaling
Aquaculture, 2013Co-Authors: Aude Jouaux, Clothilde Heude-berthelin, Pascal Sourdaine, J.l. Blin, Béatrice Adeline, M. Mathieu, K. KellnerAbstract:Gametogenesis of the Pacific oyster Crassostrea gigas follows an annual cycle. In this work, we used contrasting dietary conditions (fed and unfed) for a preconditioning treatment in order to impact glycogen storage supporting reproductive pathways in diploid and triploid animals before a broodstock conditioning treatment. In diploid oysters, food deprivation during preconditioning led to reduced gonia proliferation as demonstrated by lower PCNA (Proliferating Cell Nuclear Antigen) expression and subsequently, the reproductive effort was significantly reduced. For triploid animals exhibiting arrested Gametogenesis, dietary conditions impacted the ratio of α (animals with unlocked Gametogenesis) and β (animals with locked Gametogenesis). Thermal stress applied to these conditioned animals confirmed the weakness of diploid animals with high stored reserves and intense reproductive effort, versus low reproductive effort. Moreover, only low mortalities were observed for triploid animals whatever the reproductive status. The involvement of the insulin pathway in the regulation of Gametogenesis and storage rebuilding was assessed by measuring an increased expression of CIR (C. gigas insulin related receptor) in unfed oysters.
