Abstract
Endocrine-disrupting compounds in water affect reproductive activities in fish. Mercury is a toxic and persistent pollutant, which bioaccumulates in the food chain. To investigate the effect of mercury chloride (HgCl) on fish reproduction, animals were kept in four aquaria containing increasing levels of HgCl (0 mg/L [control]; 0.025 mg/L [low]; 0.05 mg/L [medium]; 0.1 mg/L [high]) for 60 days. The effects of HgCl on reproduction performance of male silver sharkminnow were evaluated by GtH-Ia, GtH-IIa and GtH-IIb gene expression, testosterone levels, and GSI levels. A significant decrease in Gonadothropin Hormone type I sub unit alpha (GtH-Ia), Gonadothropin Hormone type II sub unit alpha (GtH-IIa) and Gonadothropin Hormone type II sub unit beta (GtH-IIb) gene expression, testosterone levels, and Gonado Somatic Index (GSI) levels was detected in fish receiving the high mercury dose compared to controls after 2, 4, 6 and 8 weeks (P < 0.05). After 4, 6 and 8 weeks, all treatment groups had significantly lower GtH-Ia, GtH-IIa and GtH-IIb gene expression, testosterone levels and GSI levels compared to the control group (P < 0.05). These findings demonstrate a disruptive role of mercury on reproductive performance in male silver sharkminnow.
Highlights
Reproductive activities in fish are regulated by several environmental and physiological factors (Bromage et al 2001; Rodriguez et al 2004)
In the present study we investigated the specific effects of HgCl concentration, on gene expression of Gonadothropin Hormone type I sub unit alpha (GtH-Ia), Gonadothropin Hormone type II sub unit alpha (GtH-IIa) and Gonadothropin Hormone type II sub unit beta (GtH-IIb), testosterone, Gonado Somatic Index (GSI) and spermatid proportion in male silver sharkminnow Osteochilus hasseltii (Valenciennes, 1842)
Expression levels of GtH-IIa mRNA in HgCl-treated groups and the control group at the second week and fourth week were not significantly different (P > 0.05)
Summary
Reproductive activities in fish are regulated by several environmental and physiological factors (Bromage et al 2001; Rodriguez et al 2004). The GtHs regulate the two main activities of the gonads, i.e. hormone and gamete production (Kamler 1992; Rodriguez et al 2004). GtH-II levels are low during the early stages of the reproductive cycle; they increase during spermiation in males (Breton et al 1998). Both GtHs are equipotent in stimulating testosterone (T2) production (Sulistyo et al 1998), but GtH-II is more potent than GtH-I in stimulating maturation-inducing steroid, DHP (17, 20-dihydroxy-pregnen- 3one) (Saligaut et al 1998; Utoh et al 2003)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
