Role of sex steroids in gonadal differentiation of the mussel Choromytilus chorus (Bivalvia Mytilidae) (Molina 1782) (original) (raw)
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Possible roles of sex steroids in the control of reproduction in bivalve molluscs
Aquaculture, 2007
The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration.
Aquaculture, 2004
Previous work has demonstrated the presence of various sex steroids in molluscs and suggested their possible functions in the control of reproduction. However, their potential roles in early sexual development have remained unexplored. The results of the present study showed that injections of estradiol, testosterone, progesterone, and dehydroepiandrosterone (DHEA) all accelerated gonadal differentiation and shifted sex ratios toward more males in the sea scallop. Morphological changes were also observed in the females of steroid-injected groups. Estradiol appeared to stimulate oocyte growth while testosterone appeared to induce degeneration of oocytes. No parallel changes were noted in males of steroid-injected groups. Hermaphroditic animals were also found in the progesterone-and DHEA-injected groups. Together, these results support the hypothesis that sex steroids are involved in invertebrate reproduction and may be exploited for gender manipulation in bivalve aquaculture. D
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2015
This paper reports on sex-related differences in free steroid hormone concentrations including the concentrations of three naturally occurring estrogens (17β-estradiol E2, estrone E1, and estriol E3) and one androgen (testosterone T) in the tissues (gills and gonads) of the blue mussel Mytilus edulis trossulus sampled from the Gulf of Gdańsk (Baltic Sea, Poland). The dissimilarity in steroid concentrations between tissues was particularly evident in the T concentration with a level in gills almost three times higher compared to gonads (on average, 15.38 ng/g w.w. and 5.31 ng/g w.w., respectively, p = 0.00008), suggesting its exogenous origin. In general, a tendency towards a skewed steroid profile related to sex, with E2 more abundant for males and T for females, was observed. Female gonads were characterized by a higher level of T than testis (4.61 ng/g w.w. for females and 0.70 ng/g w.w. for males, p = 0.0121). At the same time, the level of E2 found in the testis was higher than in the ovary (4.81 ng/g w.w. and 3.86 ng/g w.w., respectively); however, the difference was not statistically significant. As for gills, similar trend with T and E2 being more abundant in males was observed. At the same time, no disturbances in the sex ratio and gametogenesis process were observed which suggests i) efficient deactivation of free forms of steroids, and/or ii) their little or no physiological role.
General and Comparative Endocrinology, 2006
Perturbation of the reproductive cycle as well as vitellin-like protein synthesis have already been reported in Mya arenaria sampled in contaminated areas of the St. Lawrence maritime estuary (Québec, Canada). To assess the potential role of endocrine disruptors in modulating the reproductive cycle in clams, the role of sex steroids has to be clariWed. We determined the levels of estradiol-17 and testosterone during the reproductive cycle in female and male M. arenaria. Both steroids were measured by ELISA in the gonads and no diVerences in steroid proWles appeared between sexes. Estrogen levels varied between 150 and 400 pg g ¡1 wet weight over gametogenesis and were near 10 times higher than testosterone levels. Results showed transient increases of both steroids at the onset of vitellogenesis in females and during the spawning stage in both sexes. These Wndings indicate that these hormones could have a role as endogenous modulators of gametogenesis. Further studies are, however, needed to describe the pathway of steroid synthesis in clam gonad and elucidate steroid involvement in controlling gametogenesis and as well as their relationship with neurohormones since these latter are required to promote sexual maturation.
Peer Review #2 of "Aromatisation of steroids in the bivalve Mytilus trossulus (v0.1)
2019
In this study, we demonstrated the presence of the enzymatic complex able to perform aromatization (estrogen synthesis) in both, the microsomal and mitochondrial fractions of gills and gonads from Mytilus trossulus. Based on in vitro experiments, we highlighted the importance of temperature as the limiting factor of aromatisation efficiency (AE) in mussels. After testing range of temperatures (4°C-23°C), the highest AE was found during incubation at 8°C and pH 7.6 (41.66 pmol/h/mg protein in gills and 58.37 pmol/h/mg protein in gonads). The results were confirmed during field studies where the most efficient aromatisation occurred in bivalves collected in spring while the least effective in those collected in winter. During in vitro studies, AE turned out to be more intensive in female gonads than in male gonads. The process was also more intensive in mitochondrial fraction than in microsomal one (62.97 pmol/h/mg protein in male gills and 73.94 pmol/h/mg protein in female gonads). Enzymatic complex (aromatase-like enzyme) catalysing aromatisation in mussels was found to be insensitive to inhibitory effect of selective inhibitors of mammalian aromatase such as letrozole and anastrazole, suggesting its different structure from vertebrate aromatase. Further in vivo studies using 13 C-labelled steroids at 8°C temperature window confirmed that bivalves are able to uptake testosterone and androstenedione from the ambient environment and metabolise them to estrone and 17β-estradiol thus confirming endogenous estrogen' synthesis.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1997
ABSTRACT Estrogen levels in the gonads of marine bivalves, the Pacific oyster Crassostrea gigas and scallop Patinopecten yessoensis were determined by high performance liquid chromatography (HPLC) using an electrochemical detector. Estrone (E1), estradiol-17β (E2), and a small amount of estriol (E3) were identified in the ovary, while only E2 was found in the testis. The level of E2 in the ovary was consistently higher than E1 and it increased with sexual maturation. These results indicate that E2 may play a role in the reproductive events of the oyster and scallop. In vitro experiments demonstrated the presence of 17β-hydroxysteroid dehydrogenase (17β-HSD) in the ovaries of both bivalves. The activity of 17β-HSD in the ovary was lower in the postspawning stage than in the early differentiating stage. The evidence for the presence of aromatase activity in the scallop ovary was obtained by 3H-water assay. The immunoreactivity against 3β-hydroxysteroid dehydrogenase (3β-HSD), P450 aromatase and E2 was detected in the cells along the outside of germinal acini of the scallop ovary. It is concluded that estrogens can be synthesized in the gonad, that their levels vary with the reproductive cycle, and that they have a role in the development of gametes.
Aromatisation of steroids in the bivalveMytilus trossulus
PeerJ, 2019
In this study, we demonstrated the presence of the enzymatic complex able to perform aromatization (estrogen synthesis) in both, the microsomal and mitochondrial fractions of gills and gonads from Mytilus trossulus. Based on in vitro experiments, we highlighted the importance of temperature as the limiting factor of aromatisation efficiency (AE) in mussels. After testing range of temperatures (4-23 C), the highest AE was found during incubation at 8 C and pH 7.6 (41.66 pmol/h/mg protein in gills and 58.37 pmol/h/mg protein in gonads). The results were confirmed during field studies where the most efficient aromatisation occurred in bivalves collected in spring while the least effective in those collected in winter. During in vitro studies, AE turned out to be more intensive in female gonads than in male gonads. The process was also more intensive in mitochondrial fraction than in microsomal one (62.97 pmol/h/mg protein in male gills and 73.94 pmol/h/mg protein in female gonads). Enzymatic complex (aromatase-like enzyme) catalysing aromatisation in mussels was found to be insensitive to inhibitory effect of selective inhibitors of mammalian aromatase such as letrozole and anastrazole, suggesting its different structure from vertebrate aromatase. Further in vivo studies using 13 C-labeled steroids at 8 C temperature window confirmed that bivalves are able to uptake testosterone and androstenedione from the ambient environment and metabolise them to estrone and 17β-estradiol thus confirming endogenous estrogen' synthesis.
Sex steroids and oocyte maturation in the sterlet (Acipenser ruthenus L.)
Journal of Applied …, 2006
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General and Comparative Endocrinology, 2008
The aim of this work was to investigate in situ biometric (condition index, hepato-somatic index, gonadosomatic index), biochemical (glycogen, lipids, sexual steroids) and histological (sex, sexual maturation stage) variables in the infaunal bivalve Scrobicularia plana. First, the reproductive cycle of S. plana was assessed by collecting bivalves from a reference site (the bay of BourgneufThen, S. plana were collected at three key periods of their sexual cycle (March 2006, beginning of gametogenesis; June 2006, spawning; and September 2006, spent) in three sites differing by their level of contamination (bay of Bourgneuf, reference site; Loire and Seine estuaries; Fr, impacted sites). The reproductive cycle of S. plana was well defined with a clear spawning period between May and July, sexual repose from November to January. Development of the gonad began in January and ended in September. Sex-ratio was determined during spawning and the influence of sex on biochemical variables was examined. Progesterone, 17b-estradiol and testosterone levels in the gonad of S. plana were close to those reported in other bivalves. This study is the first to demonstrate in situ influence of site, sex and sexual maturity on energy reserves, and sexual steroids in S. plana. Even if interpretation of results is complex due to interferences between natural and anthropogenic factors, S. plana is a suitable species for estuarine studies and a better understanding of its reproduction will permit to assess impacts of environmental pollutants.