Exposure to estrogenic endocrine disrupting chemicals (EDCs) induces a range of adverse effects, notably on reproduction and reproductive development. These responses are mediated via estrogen receptors (ERs). Different species of fish may show differences in their responsiveness to environmental estrogens but there is very limited understanding on the underlying mechanisms accounting for these differences.
View Article and Find Full Text PDFAndrogens play key roles in the morphological specification of male type sex attractive and reproductive organs, whereas little is known about the developmental mechanisms of such secondary sex characters. Medaka offers a clue about sexual differentiation. They show a prominent masculine sexual character for appendage development, the formation of papillary processes in the anal fin, which has been induced in females by exogenous androgen exposure.
View Article and Find Full Text PDFJuvenile hormone is an essential regulator of major developmental and life history events in arthropods. Most of the insects use juvenile hormone III as the innate juvenile hormone ligand. By contrast, crustaceans use methyl farnesoate.
View Article and Find Full Text PDFSeveral endocrine-disrupting chemicals with estrogenic activity can affect sexual development and reproduction in aquatic wildlife. The occurrence of oocytes in the testis (testis-ova) is one reproductive disorder and can be used as a valid endpoint when studying disruptive effects of estrogenic chemicals. To elucidate the molecular basis of testis-ova induction, we conducted gene expression analysis in the gonads of Silurana tropicalis exposed to 0, 3, 10 and 30 ng l(-1) 17α-ethinylestradiol (EE2) from 2 days after fertilization to the juvenile stage (14 weeks after fertilization).
View Article and Find Full Text PDFThe occurrence of oocytes in the testis (testis-ova) of several fish species is often associated with exposure of estrogenic chemicals. However, induction mechanisms of the testis-ova remain to be elucidated. To develop marker genes for detecting testis-ova in the testis, adult male medaka were exposed to nominal concentration of 100 ng L(-1) of 17α-ethinylestradiol (EE2) for 3-5 weeks, and 800 ng estradiol benzoate (EB) for 3 weeks (experiment I), and a measured concentration of 20 ng L(-1) EE2 for 1-6 weeks (experiment II).
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