Differential Effects of Heavy Metals (Cadmium, Cobalt, Lead and Mercury) on Oocyte Maturation and Ovulation of the Catfish Heteropneustes fossilis: an In Vitro Study

Özet

The aim of the present study was to examine comparative effects of different concentrations of heavy metals such ascadmium (Cd), cobalt (Co), lead (Pb) and mercury (Hg) on catfish oocyte maturation and ovulation. Post-vitellogenic oocytesof the catfish H. fossilis were incubated with heavy metals at concentrations of 0.1, 1.0, 10 and 50ng/ml. Translucent follicleswithout germinal vesicle and opaque follicles with GV were scored after 4, 8, 16, and 24 h of incubation. Percentage GVbreakdown (GVBD) was calculated as an index of oocyte maturation. The results of present investigation suggested that theeffect of heavy metals on oocyte maturation and ovulation was in the order of Pb>Hg>Cd>Co. Pb and Hg showed significantincreases (P<0.05) in GVBD and ovulation at all concentrations during 4 and 8hr of the incubation. However, there was adose –dependent decrease at 16 and 24 h. Cd and Co showed decline in GVBD and ovulation at 16 and 24 h of the incubation.However, mercury and lead showed a stimulatory effect on ovulation at 16 and 24 h compared to control (P<0.05). Thus,these results suggest that catfish oocytes are differentially influenced by heavy metals and are resistant to them at certainlevels.