The effects of glutathione depletion on reproductive success in oysters, Crassostrea virginica

Glutathione (GSH) is a ubiquitous tripeptide that functions as a very impor tant modulator of cellular homeostasis, including detoxification of metals and oxyradicals. Therefore, depletion of GSH may predispose organisms to po llutant stress. Reproductively active oysters (Crassostrea virginica) were exposed to buthionine sulfoximine in the laboratory to deplete gonadal GSH. The effects of metal exposures (Cd and Cu) on fertilization and developmen tal assays were evaluated using gametes from control and GSH-depleted adult s. Fertilization success was not affected by GSH status, i.e. the fertiliza tion rates of gametes derived from GSH-depleted adults were the same or sli ghtly higher. However, GSH depletion did increase the susceptibility of dev eloping embryos to metal toxicity, i.e, adverse effects on embryonic develo pment were observed at lower metal concentrations with gametes derived from GSH-depleted adults. These effects may be related to diminished removal of free radicals or increased availability of metals. Whereas sperm penetrati on of embryonic membranes and fertilization success may be facilitated by f ree radicals, the persistence of free radicals during subsequent developmen tal periods may adversely affect differentiation and normal development. GS H probably also plays an important role in scavenging toxic metals and redu cing metal interactions with essential developmental processes. These resul ts suggest that parental depletion of GSH may increase the susceptibility o f embryos to metal toxicity. (C) 2000 Elsevier Science Ltd. All rights rese rved.