Endocrine regulation of gametogenesis in fish.
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TLDR
Findings on the identification of steroidal mediators involved in each process of gametogenesis, and the sites and mechanisms of action of the mediators are reviewed.Abstract:
The pituitary-gonadal axis plays an important role in regulating gametogenesis in vertebrates. In most cases, gonadotropins act through the biosynthesis of gonadal steroid hormones which in turn mediate various stages of gametogenesis. A series of studies in our laboratory using several species of teleost fishes as experimental animals has provided new information about the endocrine regulation of gametogenesis, including oocyte growth, oocyte maturation, spermatogenesis and sperm maturation. This article briefly reviews our findings on the identification of steroidal mediators involved in each process of gametogenesis, and the sites and mechanisms of action of the mediators. These observations collectively demonstrate the appropriateness of using teleost fishes as valid models for examining hormonal influences on gametogenesis. Such models could also have applications and validity for vertebrates in general.read more
Citations
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Journal ArticleDOI
Sex determination and sex differentiation in fish: an overview of genetic, physiological, and environmental influences
TL;DR: The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions, and such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.
Journal ArticleDOI
Spermatogenesis in fish.
Rüdiger W. Schulz,Luiz R. França,Jean-Jacques Lareyre,Florence Legac,Hélio Chiarini-Garcia,Rafael Henrique Nóbrega,Rafael Henrique Nóbrega,Takeshi Miura +7 more
TL;DR: In this article, the effects of progestin, androgens, and estrogens on global testicular gene expression patterns (microarray analysis), and molecular mechanisms by which steroids regulate specific candidate genes (identified by subtractive hybridization approaches) during early stages of testis maturation are discussed.
Journal ArticleDOI
Oogenesis in teleosts: How fish eggs are formed
TL;DR: Recent advances on teleost fish oocyte differentiation, maturation and ovulation are highlighted, including those involved in the degeneration and reabsorption of ovarian follicles (atresia).
Journal ArticleDOI
Oocyte growth and development in teleosts
Charles R. Tyler,John P. Sumpter +1 more
TL;DR: The mechanisms that control oocyte growth are addressed in this review, albeit that the available information, as in all other vertebrates, is very limited.
Journal ArticleDOI
Regulation of oocyte maturation in fish.
TL;DR: This article showed that oocyte maturation is a three-step induction process involving gonadotropin (LH), maturation-inducing hormone (MIH), and maturationpromoting factor (MPF).
References
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Purified maturation-promoting factor contains the product of a Xenopus homolog of the fission yeast cell cycle control gene cdc2+.
TL;DR: It is reported here that antibodies to S. pombe p34cdc2 are able to immunoblot and immunoprecipitate the approximately equal to 32 kd component of MPF from Xenopus eggs, indicating that a Xenopus p34CDc2 homolog is present in purified MPF and suggesting that p34c2 is a component of the control mechanism initiating mitosis generally in eukaryotic cells.
Journal ArticleDOI
Cyclin is a component of maturation-promoting factor from Xenopus
TL;DR: Data indicate that B-type cyclin is the other component of MPF besides p34cdc2, for which exogenously added B1 and B2 cyclins are both substrates.
Journal ArticleDOI
Purification of maturation-promoting factor, an intracellular regulator of early mitotic events
TL;DR: The highly purified preparations described here should help to identify the mechanism of action of maturation-promoting factor and to elucidate the role of protein kinases in the induction of metaphase.
Book ChapterDOI
6 The Functional Morphology of Teleost Gonads
TL;DR: This chapter discusses the functional morphology of teleost gonads and a two cell-type model involving thecal and granulosa cell layers has been proposed for the production of these two steroids for the first time in lower vertebrates.
Journal ArticleDOI
Cellular Organization of the Testis and Spermatogenesis in Fishes
TL;DR: Variations in these testis-types are discussed particularly in light of modifications leading to the production of spermatozeugmata or spermatophores, as well as nuclear elongation, coupled with possible elongation of the sperm midpiece, is characteristic of most species wherein fer?