Melatonin is considered as the time-keeping hormone acting on important physiological functions o... more Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-dependent. Innate immune markers, including lysozyme, complement, peroxidase and phagocytic activities, were stimulated by the fall-simulated photoperiod and a significant correlation was made with plasma melatonin. In addition to bring the first evidence of changes in fish immunocompetence related to photoperiod, our results provide an additional indication supporting the immunomodulatory action of melatonin in teleosts.
HAL (Le Centre pour la Communication Scientifique Directe), Aug 29, 2006
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
In this study, the systematic development of a protocol allowing an effective advanced spawning o... more In this study, the systematic development of a protocol allowing an effective advanced spawning of wild Eurasian perch with the use of salmon gonadoliberin analogue (sGnRHa) was undertaken. The novel approach used in this study involved the application of a strategy of the repeated administration of sGnRHa (i.e., the hormone was given in two doses: priming and resolving) along with an additional thermal stimulation of ovulation. Additionally, the developed protocol was tested for its suitability in the controlled reproduction of domesticated broodstock. The obtained results suggested that the best interval between the hormonal treatments is 7 days when a water temperature of 10°C is kept constant between the two injections and when the resolving injection is followed by rapid increments of temperature up to 12°C, at which spawning is expected. This study revealed that the most suitable priming dose of sGnRHa was 10 µg kg -1 , at which the highest embryonic survival rates (>80%) and spawning efficiency indexes (>500 larvae kg -1 ) (SEI: representing the number of larvae with an inflated swim bladder obtained from 1 kg of a spawned female) were recorded. Furthermore, in most cases, the application of the resolving injection yielded an embryonic survival rate of over 85% with the highest ovulation rate (100%) and SEI values observed in the group injected with 10 and 25 µg kg -1 at the priming and resolving doses, respectively. Repeated administrations of sGnRHa were more effective than a previous strategy typically applied for the induction of ovulation in Eurasian perch (a single application of sGnRHa or human chorionic gonadotropin). Moreover, the protocol applied to wild perch can be fully transferrable to domesticated broodstock, which makes it a valuable tool for the improvement of controlled reproduction of this species for intensive aquaculture purposes.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The aim of this study was to assess monthly testicular development in the cultured breeding stock... more The aim of this study was to assess monthly testicular development in the cultured breeding stock of sterlet, Acipenser ruthenus, using histological and serum sex steroid changes. Testicular development in the adult male was examined monthly and showed four distinct phases including resting, pre-spawning, spawning and post-spawning. Also, seasonal changes of the testes were described according to its variations in gonadosomatic index (GSI) during different phases of testicular development. Using histology, we identified continuous spermatogenesis and asynchronous gonad development pattern in the testes of male sterlet, which shows that regulation of annual gonadal cycle is influenced by season. Results also showed variation in the GSI value and number of spermatogenic cells according to each season during annual cycle of gonad, as the highest value of GSI was recorded during spawning phase (spring; March-May). Hormonal profiles of 11-ketotestosterone (11-KT) showed peak, which indicated a seasonal pattern of gonadal development. The 11-KT concentration increased considerably during the spermatogenesis (pre-spawning phase) and remained quite high throughout the pre-spermiation period. In the final phase of testicular development (spawning phase), the 11-KT markedly dropped. This study undertook an examination of complete reproductive development in cultured sterlet sturgeon to provide a valuable guide for the future sterlet studies, and allows comparison of reproductive development between sturgeon species.
This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pikeperch (San... more This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pikeperch (Sander lucioperca) broodstock fed a commercial diet with low levels of long-chain polyunsaturated fatty acids (Lc-PUFA) and wild (F0) pike-perch broodstock fed forage fish. Reproductive parameters, including pseudogonadosomatic index (PGSI), egg size, latency time, hatching rate, embryo survival, and eggs' fatty acid (FA) composition, as well as plasma sex hormone, glucose and immunoglobulin levels after hormone injection, were analyzed. The results showed low PGSI (10% in F1 vs. 14% in F0) and embryo survival (24% in F1 vs. 61% in F0) in F1 broodstock, but a satisfactory hatching rate (63% in F1 vs. 78% in F0) and larval size (4.6 mm in F1 vs. 4.7 mm in F0). A low arachidonic acid (ARA) percentage in F1 fish eggs (1.32%), along with increased immunoglobulin levels (17.31 g/L), suggests that immune system activation might have depleted the reserves of ARA in F1 fish, which is the key fatty acid for successful oocyte maturation. We assumed that the administration of more sustainable diets, based on terrestrial plant ingredients, is not inferior to higher-quality diets based on marine ingredients.
Additional file 2: Figure S2. Barplots representing results obtained for all key traits studied (... more Additional file 2: Figure S2. Barplots representing results obtained for all key traits studied (n = 3 per population, except for activity and inter-individual distances for which n=9). Different letters indicate significant differences between populations (p-value<0.05) using post-hoc tests.
This study aimed to assess the effect of constant darkness applied to fish during controlled bree... more This study aimed to assess the effect of constant darkness applied to fish during controlled breeding on reproductive traits in domesticated females of Eurasian perch. Based on the assumption that keeping fish in constant darkness during the reproduction operation may reduce stress, suspected to be responsible for variable spawning effectiveness in this species. Two conditions were assessed (16 h light per day [group 16L] and constant darkness [group 0L], two tank replicates per condition). The reproductive protocol involved a 7-day-long adaptation period for group 0L where photoperiod was reduced by 2.3 h a day down to constant darkness. After the adaptation period, two hormone injections (salmon gonadoliberin analogue) were applied to both groups: priming (10 mg/kg) and resolving (25 mg/kg) with a 7-day interval between them. During the study, morphometric indices were recorded and blood, brain, and pituitary samples were collected to assess stress markers and determine hypothalamic-pituitary-gonadal axis functioning via measuring blood plasma hormones, as well as gonadoliberin and gonadotropins (luteinising hormone [LH] and follicle-stimulating hormone [FSH]) transcript abundance (n = 7 for each group at each sampling point). In addition, kinetics of the final oocyte maturation (FOM) process, ovulation rate, and egg quality of each group was monitored (n = 12 for each group). The results indicated that there were no differences in terms of morphometry, FOM kinetics, and most stress indices between groups throughout the experiment, except haematocrit, which increased immediately following the acclimation period in fish kept in darkness. Constant darkness negatively affected plasma levels of 17a,20b-dihy droxy-4-pregnen-3-one (DHP) and LH transcript expression at the time of the second hormone injection. This indicated that exposure to constant darkness negatively affected priming of the hormonal dose applied, resulted in the disruption of ovulation, and reduced ovulation rates (50%) for group 0L, as compared to 16L (91%). The findings of this study clearly indicate that constant darkness may have significant deleterious effects on reproductive traits throughout out-of-season induced, hormonally supported, controlled reproduction. Therefore, we advise against the use of constant darkness when managing broodstock reproduction in domesticated Eurasian perch.
The aim of this study was to evaluate seasonal testicular development in the cultured sterlet, Ac... more The aim of this study was to evaluate seasonal testicular development in the cultured sterlet, Acipenser ruthenus. During annual sexual cycle of male sterlet, stages of gonad maturity were examined using histology and ultrasonography approaches. The histology identified males at different stages of maturity among fish sampled monthly. According to the seasonal changes in the testes, reproductive cycle was divided into four stages including resting, pre-spawning, spawning, and post-spawning. The histology examination revealed considerable variation in testicular developmental stages. These changes were identified based on persistent spermatogenesis and asynchronous gonad development in testes, showing that regulation of annual gonadal cycle is influenced by season. Also, the results obtained using ultrasound suggested that reproductive stages can be identified based on morphology and tissue echogenicity. At each phase of testicular development, gonadosomatic index (GSI) and number of spermatogenic cysts were variable. The present study focused on determination of annual reproductive development in cultured male sterlet which clearly identifies reproductive stage in each season as valuable guide for future researches on reproductive biology of sterlet. This study presents basic knowledge about reproductive biology in sterlet contributing to optimal broodstocks management that allows comparison of reproductive development among sturgeon species.
This study was designed to determine the influence of the thermal level and duration of chilling ... more This study was designed to determine the influence of the thermal level and duration of chilling period on the initiation and progress of gonadogenesis and gametogenesis under controlled conditions in pikeperch (Sander lucioperca). A set of 120 fish was distributed into eight tanks (15 fish per tank). The effects of two temperatures (6 or 12°C) in combination with two durations of chilling period, either short (S; 75 days at 6°C and 125 days at 12°C) or long (L; 135 days at 6°C and 185 days at 12°C), were investigated for the effect on growth, gonadosomatic index (GSI), hepatosomatic index (HSI), gamete developmental stage and sex‐steroid levels (17 beta‐estradiol‐E2 and testosterone‐T). These zootechnical and physiological parameters were selected as they reflect the progressive advancement of gametogenesis in percids including pikeperch. The results show that the temperature did not affect the reproductive parameters but down‐regulated the HSI and the condition factor in females. ...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics, 2020
Dopamine (DA) is a ubiquitous neurotransmitter exerting a range of pleiotropic actions through tw... more Dopamine (DA) is a ubiquitous neurotransmitter exerting a range of pleiotropic actions through two DA receptor families, the D1 and the D2. To date in vertebrates, a maximum of four receptor subtypes have been identified within the D1 family, D 1 (former D 1A ), D 5 (former D 1B ), D 6 (former D 1C ) and D 7 (former D 1E ), while the D2 family encloses five subtypes, D 2 , D 3 , D 4 , D 8 (former D 2like or D 2l ) and D 9 (former D 4-related sequence or D 4-rs ). In teleosts, no study has investigated in parallel all the DA receptors to identify and localize the whole receptor repertoire from both families. In pikeperch, Sander lucioperca, a species of interest for aquaculture development, the existence, number and location of the DA receptors are totally unknown. To address these questions, RNA-seq with de novo transcriptome reconstruction, functional annotation and phylogenetic analysis were performed to characterize the transcript repertoire of DA receptors in the brain of female pikeperch at the pre-ovulatory period. Ten different cDNA were identified and showed to belong to the D1 family: two D 1 , one D 5a , one D 6a and one D 6b and to the D2 family: two spliced variants of D 2 , one D 3 , one D 8 and one D 9. Unlike zebrafish, the subtypes D 4 and D 7 have not yet been isolated in pikeperch. As expected D 1 , D 3 , D 8 and D 9 are mostly expressed in brain parts except for the cerebellum (D 1 and D 3 ). The inter-species differences in the number of DA receptors and the inter-organ differences in the gene expression of all receptors support the complexity of the dopaminergic actions in vertebrate.
Melatonin is considered as the time-keeping hormone acting on important physiological functions o... more Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-...
In this study, the systematic development of a protocol allowing an effective advanced spawning o... more In this study, the systematic development of a protocol allowing an effective advanced spawning of wild Eurasian perch with the use of salmon gonadoliberin analogue (sGnRHa) was undertaken. The novel approach used in this study involved the application of a strategy of the repeated administration of sGnRHa (i.e., the hormone was given in two doses: priming and resolving) along with an additional thermal stimulation of ovulation. Additionally, the developed protocol was tested for its suitability in the controlled reproduction of domesticated broodstock. The obtained results suggested that the best interval between the hormonal treatments is 7 days when a water temperature of 10°C is kept constant between the two injections and when the resolving injection is followed by rapid increments of temperature up to 12°C, at which spawning is expected. This study revealed that the most suitable priming dose of sGnRHa was 10 µg kg -1 , at which the highest embryonic survival rates (>80%) and spawning efficiency indexes (>500 larvae kg -1 ) (SEI: representing the number of larvae with an inflated swim bladder obtained from 1 kg of a spawned female) were recorded. Furthermore, in most cases, the application of the resolving injection yielded an embryonic survival rate of over 85% with the highest ovulation rate (100%) and SEI values observed in the group injected with 10 and 25 µg kg -1 at the priming and resolving doses, respectively. Repeated administrations of sGnRHa were more effective than a previous strategy typically applied for the induction of ovulation in Eurasian perch (a single application of sGnRHa or human chorionic gonadotropin). Moreover, the protocol applied to wild perch can be fully transferrable to domesticated broodstock, which makes it a valuable tool for the improvement of controlled reproduction of this species for intensive aquaculture purposes.
Upon infection, B-lymphocytes expressing antibodies specific for the intruding pathogen develop c... more Upon infection, B-lymphocytes expressing antibodies specific for the intruding pathogen develop clonal responses triggered by pathogen recognition via the B-cell receptor. In teleost fish, in absence of lymph nodes the kinetics and anatomy of B-cell responses remain poorly characterized. After B cells encounter their specific target, they differentiate into Ab secreting cells probably in spleen or kidney, and it is believed that mature plasma cells migrate and persist in the anterior kidney. Here, we undertook a comparative analysis of the variable heavy chain (VH) domain repertoires of the IgM and IgT in the head kidney of isogenic rainbow trout (Oncorhynchus mykiss) lines after primary infection, vaccination and boost with an attenuated strain of the rhabdovirus Viral Hemorrhagic Septicemia Virus (VHSV). We used a barcoded IgH cDNA sequencing approach to characterise the modifications of the antibody repertoire, through the analysis of VH usage in expressed V(D)J rearrangements, clonal diversity, frequency of clonotypes, clonotype distribution and sharing between individual fish and treatments, which is determined by convergent response to Ag and probability of generation by the recombination process. We found extensive modifications implicating most VH families one month after primary infection. In contrast, only modest changes in terms of repertoire diversity and composition were observed 5 months postvaccination with the attenuated VHSV vaccine. A boost performed 5 months post vaccination induced additional alterations of the kidney IgH repertoire detected after one week, but they faded after one month. The IgM public response implicating VH5 and JH5, that we previously described in spleen, was again observed in all infected fish confirming its presence among B cells from the head kidney and its strong correlation with the response against the virus. Our results provide insights about the amplitude of the primary and secondary B cell response to VHSV infection in the tissue in which plasma cells and memory cells accumulate. Together with a standardisation effort of salmonid Ig genes annotation, these data pave the way for a better monitoring of B cell response kinetics in lymphoid tissues, an essential step to understand B memory mechanisms in fish.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Melatonin is considered as the time-keeping hormone acting on important physiological functions o... more Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-dependent. Innate immune markers, including lysozyme, complement, peroxidase and phagocytic activities, were stimulated by the fall-simulated photoperiod and a significant correlation was made with plasma melatonin. In addition to bring the first evidence of changes in fish immunocompetence related to photoperiod, our results provide an additional indication supporting the immunomodulatory action of melatonin in teleosts.
HAL (Le Centre pour la Communication Scientifique Directe), Aug 29, 2006
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
In this study, the systematic development of a protocol allowing an effective advanced spawning o... more In this study, the systematic development of a protocol allowing an effective advanced spawning of wild Eurasian perch with the use of salmon gonadoliberin analogue (sGnRHa) was undertaken. The novel approach used in this study involved the application of a strategy of the repeated administration of sGnRHa (i.e., the hormone was given in two doses: priming and resolving) along with an additional thermal stimulation of ovulation. Additionally, the developed protocol was tested for its suitability in the controlled reproduction of domesticated broodstock. The obtained results suggested that the best interval between the hormonal treatments is 7 days when a water temperature of 10°C is kept constant between the two injections and when the resolving injection is followed by rapid increments of temperature up to 12°C, at which spawning is expected. This study revealed that the most suitable priming dose of sGnRHa was 10 µg kg -1 , at which the highest embryonic survival rates (>80%) and spawning efficiency indexes (>500 larvae kg -1 ) (SEI: representing the number of larvae with an inflated swim bladder obtained from 1 kg of a spawned female) were recorded. Furthermore, in most cases, the application of the resolving injection yielded an embryonic survival rate of over 85% with the highest ovulation rate (100%) and SEI values observed in the group injected with 10 and 25 µg kg -1 at the priming and resolving doses, respectively. Repeated administrations of sGnRHa were more effective than a previous strategy typically applied for the induction of ovulation in Eurasian perch (a single application of sGnRHa or human chorionic gonadotropin). Moreover, the protocol applied to wild perch can be fully transferrable to domesticated broodstock, which makes it a valuable tool for the improvement of controlled reproduction of this species for intensive aquaculture purposes.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The aim of this study was to assess monthly testicular development in the cultured breeding stock... more The aim of this study was to assess monthly testicular development in the cultured breeding stock of sterlet, Acipenser ruthenus, using histological and serum sex steroid changes. Testicular development in the adult male was examined monthly and showed four distinct phases including resting, pre-spawning, spawning and post-spawning. Also, seasonal changes of the testes were described according to its variations in gonadosomatic index (GSI) during different phases of testicular development. Using histology, we identified continuous spermatogenesis and asynchronous gonad development pattern in the testes of male sterlet, which shows that regulation of annual gonadal cycle is influenced by season. Results also showed variation in the GSI value and number of spermatogenic cells according to each season during annual cycle of gonad, as the highest value of GSI was recorded during spawning phase (spring; March-May). Hormonal profiles of 11-ketotestosterone (11-KT) showed peak, which indicated a seasonal pattern of gonadal development. The 11-KT concentration increased considerably during the spermatogenesis (pre-spawning phase) and remained quite high throughout the pre-spermiation period. In the final phase of testicular development (spawning phase), the 11-KT markedly dropped. This study undertook an examination of complete reproductive development in cultured sterlet sturgeon to provide a valuable guide for the future sterlet studies, and allows comparison of reproductive development between sturgeon species.
This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pikeperch (San... more This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pikeperch (Sander lucioperca) broodstock fed a commercial diet with low levels of long-chain polyunsaturated fatty acids (Lc-PUFA) and wild (F0) pike-perch broodstock fed forage fish. Reproductive parameters, including pseudogonadosomatic index (PGSI), egg size, latency time, hatching rate, embryo survival, and eggs' fatty acid (FA) composition, as well as plasma sex hormone, glucose and immunoglobulin levels after hormone injection, were analyzed. The results showed low PGSI (10% in F1 vs. 14% in F0) and embryo survival (24% in F1 vs. 61% in F0) in F1 broodstock, but a satisfactory hatching rate (63% in F1 vs. 78% in F0) and larval size (4.6 mm in F1 vs. 4.7 mm in F0). A low arachidonic acid (ARA) percentage in F1 fish eggs (1.32%), along with increased immunoglobulin levels (17.31 g/L), suggests that immune system activation might have depleted the reserves of ARA in F1 fish, which is the key fatty acid for successful oocyte maturation. We assumed that the administration of more sustainable diets, based on terrestrial plant ingredients, is not inferior to higher-quality diets based on marine ingredients.
Additional file 2: Figure S2. Barplots representing results obtained for all key traits studied (... more Additional file 2: Figure S2. Barplots representing results obtained for all key traits studied (n = 3 per population, except for activity and inter-individual distances for which n=9). Different letters indicate significant differences between populations (p-value<0.05) using post-hoc tests.
This study aimed to assess the effect of constant darkness applied to fish during controlled bree... more This study aimed to assess the effect of constant darkness applied to fish during controlled breeding on reproductive traits in domesticated females of Eurasian perch. Based on the assumption that keeping fish in constant darkness during the reproduction operation may reduce stress, suspected to be responsible for variable spawning effectiveness in this species. Two conditions were assessed (16 h light per day [group 16L] and constant darkness [group 0L], two tank replicates per condition). The reproductive protocol involved a 7-day-long adaptation period for group 0L where photoperiod was reduced by 2.3 h a day down to constant darkness. After the adaptation period, two hormone injections (salmon gonadoliberin analogue) were applied to both groups: priming (10 mg/kg) and resolving (25 mg/kg) with a 7-day interval between them. During the study, morphometric indices were recorded and blood, brain, and pituitary samples were collected to assess stress markers and determine hypothalamic-pituitary-gonadal axis functioning via measuring blood plasma hormones, as well as gonadoliberin and gonadotropins (luteinising hormone [LH] and follicle-stimulating hormone [FSH]) transcript abundance (n = 7 for each group at each sampling point). In addition, kinetics of the final oocyte maturation (FOM) process, ovulation rate, and egg quality of each group was monitored (n = 12 for each group). The results indicated that there were no differences in terms of morphometry, FOM kinetics, and most stress indices between groups throughout the experiment, except haematocrit, which increased immediately following the acclimation period in fish kept in darkness. Constant darkness negatively affected plasma levels of 17a,20b-dihy droxy-4-pregnen-3-one (DHP) and LH transcript expression at the time of the second hormone injection. This indicated that exposure to constant darkness negatively affected priming of the hormonal dose applied, resulted in the disruption of ovulation, and reduced ovulation rates (50%) for group 0L, as compared to 16L (91%). The findings of this study clearly indicate that constant darkness may have significant deleterious effects on reproductive traits throughout out-of-season induced, hormonally supported, controlled reproduction. Therefore, we advise against the use of constant darkness when managing broodstock reproduction in domesticated Eurasian perch.
The aim of this study was to evaluate seasonal testicular development in the cultured sterlet, Ac... more The aim of this study was to evaluate seasonal testicular development in the cultured sterlet, Acipenser ruthenus. During annual sexual cycle of male sterlet, stages of gonad maturity were examined using histology and ultrasonography approaches. The histology identified males at different stages of maturity among fish sampled monthly. According to the seasonal changes in the testes, reproductive cycle was divided into four stages including resting, pre-spawning, spawning, and post-spawning. The histology examination revealed considerable variation in testicular developmental stages. These changes were identified based on persistent spermatogenesis and asynchronous gonad development in testes, showing that regulation of annual gonadal cycle is influenced by season. Also, the results obtained using ultrasound suggested that reproductive stages can be identified based on morphology and tissue echogenicity. At each phase of testicular development, gonadosomatic index (GSI) and number of spermatogenic cysts were variable. The present study focused on determination of annual reproductive development in cultured male sterlet which clearly identifies reproductive stage in each season as valuable guide for future researches on reproductive biology of sterlet. This study presents basic knowledge about reproductive biology in sterlet contributing to optimal broodstocks management that allows comparison of reproductive development among sturgeon species.
This study was designed to determine the influence of the thermal level and duration of chilling ... more This study was designed to determine the influence of the thermal level and duration of chilling period on the initiation and progress of gonadogenesis and gametogenesis under controlled conditions in pikeperch (Sander lucioperca). A set of 120 fish was distributed into eight tanks (15 fish per tank). The effects of two temperatures (6 or 12°C) in combination with two durations of chilling period, either short (S; 75 days at 6°C and 125 days at 12°C) or long (L; 135 days at 6°C and 185 days at 12°C), were investigated for the effect on growth, gonadosomatic index (GSI), hepatosomatic index (HSI), gamete developmental stage and sex‐steroid levels (17 beta‐estradiol‐E2 and testosterone‐T). These zootechnical and physiological parameters were selected as they reflect the progressive advancement of gametogenesis in percids including pikeperch. The results show that the temperature did not affect the reproductive parameters but down‐regulated the HSI and the condition factor in females. ...
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics, 2020
Dopamine (DA) is a ubiquitous neurotransmitter exerting a range of pleiotropic actions through tw... more Dopamine (DA) is a ubiquitous neurotransmitter exerting a range of pleiotropic actions through two DA receptor families, the D1 and the D2. To date in vertebrates, a maximum of four receptor subtypes have been identified within the D1 family, D 1 (former D 1A ), D 5 (former D 1B ), D 6 (former D 1C ) and D 7 (former D 1E ), while the D2 family encloses five subtypes, D 2 , D 3 , D 4 , D 8 (former D 2like or D 2l ) and D 9 (former D 4-related sequence or D 4-rs ). In teleosts, no study has investigated in parallel all the DA receptors to identify and localize the whole receptor repertoire from both families. In pikeperch, Sander lucioperca, a species of interest for aquaculture development, the existence, number and location of the DA receptors are totally unknown. To address these questions, RNA-seq with de novo transcriptome reconstruction, functional annotation and phylogenetic analysis were performed to characterize the transcript repertoire of DA receptors in the brain of female pikeperch at the pre-ovulatory period. Ten different cDNA were identified and showed to belong to the D1 family: two D 1 , one D 5a , one D 6a and one D 6b and to the D2 family: two spliced variants of D 2 , one D 3 , one D 8 and one D 9. Unlike zebrafish, the subtypes D 4 and D 7 have not yet been isolated in pikeperch. As expected D 1 , D 3 , D 8 and D 9 are mostly expressed in brain parts except for the cerebellum (D 1 and D 3 ). The inter-species differences in the number of DA receptors and the inter-organ differences in the gene expression of all receptors support the complexity of the dopaminergic actions in vertebrate.
Melatonin is considered as the time-keeping hormone acting on important physiological functions o... more Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-...
In this study, the systematic development of a protocol allowing an effective advanced spawning o... more In this study, the systematic development of a protocol allowing an effective advanced spawning of wild Eurasian perch with the use of salmon gonadoliberin analogue (sGnRHa) was undertaken. The novel approach used in this study involved the application of a strategy of the repeated administration of sGnRHa (i.e., the hormone was given in two doses: priming and resolving) along with an additional thermal stimulation of ovulation. Additionally, the developed protocol was tested for its suitability in the controlled reproduction of domesticated broodstock. The obtained results suggested that the best interval between the hormonal treatments is 7 days when a water temperature of 10°C is kept constant between the two injections and when the resolving injection is followed by rapid increments of temperature up to 12°C, at which spawning is expected. This study revealed that the most suitable priming dose of sGnRHa was 10 µg kg -1 , at which the highest embryonic survival rates (>80%) and spawning efficiency indexes (>500 larvae kg -1 ) (SEI: representing the number of larvae with an inflated swim bladder obtained from 1 kg of a spawned female) were recorded. Furthermore, in most cases, the application of the resolving injection yielded an embryonic survival rate of over 85% with the highest ovulation rate (100%) and SEI values observed in the group injected with 10 and 25 µg kg -1 at the priming and resolving doses, respectively. Repeated administrations of sGnRHa were more effective than a previous strategy typically applied for the induction of ovulation in Eurasian perch (a single application of sGnRHa or human chorionic gonadotropin). Moreover, the protocol applied to wild perch can be fully transferrable to domesticated broodstock, which makes it a valuable tool for the improvement of controlled reproduction of this species for intensive aquaculture purposes.
Upon infection, B-lymphocytes expressing antibodies specific for the intruding pathogen develop c... more Upon infection, B-lymphocytes expressing antibodies specific for the intruding pathogen develop clonal responses triggered by pathogen recognition via the B-cell receptor. In teleost fish, in absence of lymph nodes the kinetics and anatomy of B-cell responses remain poorly characterized. After B cells encounter their specific target, they differentiate into Ab secreting cells probably in spleen or kidney, and it is believed that mature plasma cells migrate and persist in the anterior kidney. Here, we undertook a comparative analysis of the variable heavy chain (VH) domain repertoires of the IgM and IgT in the head kidney of isogenic rainbow trout (Oncorhynchus mykiss) lines after primary infection, vaccination and boost with an attenuated strain of the rhabdovirus Viral Hemorrhagic Septicemia Virus (VHSV). We used a barcoded IgH cDNA sequencing approach to characterise the modifications of the antibody repertoire, through the analysis of VH usage in expressed V(D)J rearrangements, clonal diversity, frequency of clonotypes, clonotype distribution and sharing between individual fish and treatments, which is determined by convergent response to Ag and probability of generation by the recombination process. We found extensive modifications implicating most VH families one month after primary infection. In contrast, only modest changes in terms of repertoire diversity and composition were observed 5 months postvaccination with the attenuated VHSV vaccine. A boost performed 5 months post vaccination induced additional alterations of the kidney IgH repertoire detected after one week, but they faded after one month. The IgM public response implicating VH5 and JH5, that we previously described in spleen, was again observed in all infected fish confirming its presence among B cells from the head kidney and its strong correlation with the response against the virus. Our results provide insights about the amplitude of the primary and secondary B cell response to VHSV infection in the tissue in which plasma cells and memory cells accumulate. Together with a standardisation effort of salmonid Ig genes annotation, these data pave the way for a better monitoring of B cell response kinetics in lymphoid tissues, an essential step to understand B memory mechanisms in fish.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
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