Mechanism of action of mercury on sperm morphology, adenosine triphosphate content, and motility in Perca fluviatilis (Percidae; Teleostei)

The main objectives of the present study were to investigate the performance of mercury chloride (HgCl2 ) on sperm function and structure, identify sites of action of HgCl2 , and investigate the mechanism of action of HgCl2 on fish (Perca fluviatilis L.) spermatozoa. Direct exposure of nonincubated sperm decreased sperm motility and velocity in a dose-dependent manner and was totally suppressed at 250 µM HgCl2 .

Adenosine-5'-triphosphate (ATP) content of sperm after activation in an activation medium (AM) containing more than 25 µM HgCl2 did not differ compared with nonactivated sperm. Motility and velocity of demembranated sperm decreased after activation in an AM containing 62 µM HgCl2 , and was totally suppressed at 250 µM HgCl2 .

Incubation of sperm in an immobilizing medium (IM) containing HgCl2 enhanced HgCl2 effects after sperm activation in an AM containing HgCl2 . Sperm motility of incubated sperm in an IM without HgCl2 was totally suppressed at 125 µM HgCl2 after 3 h incubation. In case of incubated sperm in an IM containing HgCl2 , sperm motility was totally suppressed at 31 µM HgCl2 .

Adenosine-5'-triphosphate content of sperm was significantly lower in an IM containing HgCl2 greater than 3 µM compared with those of the control (no HgCl2 ) and lower HgCl2 concentrations. Damage to the plasma membrane and axoneme were observed in sperm incubated in an IM containing HgCl2 compared with the control, when HgCl2 concentration and incubation time increased.

In conclusion, HgCl2 acts on sperm through disruption of function of the plasma membrane, axoneme, and ATP content.