Changes in lipid profiles and 32P-uptake into phosphoprotein (vitellogenin) content of the ovary and liver in the female catfish, Clarias batrachus, exposed to mercury.

Toxic effects of selected sublethal concentrations of mercuric chloride (HgCl2, 0.05 mg.L-1), methylmercuric chloride (CH3HgCl, 0.04 mg.L-1) and Emisan 6 (an organic mercurial fungicide, 0.5 mg.L-1) on levels of lipids (total lipids-TL, phospholipids-PL, free cholesterol-FC; esterified cholesterol-EC and free fatty acids-FFA), and uptake of 32P into phosphoprotein fraction of the ovary and liver are reported in Clarias batrachus exposed for 45, 90 and 180 days from February to July (preparatory to spawning phase of the annual reproductive cycle). The TL level decreased significantly only in the ovary of 180-day Hg groups. The ovarian PL and FC levels showed a significant reduction at all durations of Hg exposure. In contrast, the hepatic PL and FC levels increased significantly at all durations except the PL content in the 45-day Emisan 6 and CH3HgCl groups. The EC level in the ovary showed a significant decline after both 90 and 180 days of Hg treatment whereas in the liver, it decreased significantly only after 180 days. The level of FFA in the ovary decreased significantly only in the 180-day HgCl2 group while in the liver, it showed a significant increase in all the 180-day Hg groups. The rate and level of incorporation of 32P into phosphoprotein fraction of the ovary and liver showed a progressive decline in the Hg-treated groups, the effect being significantly different only after 90 and 180 days. The results suggest that the decrease in ovarian lipid levels is largely due to their immobilization from the liver and the reduction in vitellogenin content may be due to both the inhibition of its synthesis in the liver and subsequent incorporation into the ovary.