Project Summary (1995-2000)

Objectives of this research are to study the effects of trace cadmium (Cd) levels on spermatogenesis. Epidemiological studies indicate that male gametes and the complex, hormone-regulated processes by which germ cell proliferation, development and survival are controlled, may be threatened by environmental contaminants. By virtue of a long biological half-life, cadmium (Cd) exemplifies a trace environmental pollutant with potential as a cumulative toxicant. Although spermatogenesis is exquisitely sensitive to Cd toxicity, attempts to pinpoint sensitive stages, cell-types and mechanisms of action have been hampered by the complex testicular organization of common laboratory mammals. A technically advantageous alternative is the shark testis, which facilitates analysis of spermatogenesis state-by-stage and allows intact germinal units to be isolated for experimentation and analysis in vitro. Experiments will be performed to test the hypothesis that Cd has direct access to germ cells in early developmental stages, is taken up by an active Cd-accumulating mechanism that is further amplified by enhanced metallothionein (Mt) expression, and activates a cell death program by perturbing normal control mechanisms.