Developmental patterns of zygotes from transgenic female mice with elevated tissue glutathione

Zygotes were collected from transgenic mice overexpressing glutathione synthetase to test the hypothesis that such zygotes are more capable of developing in suboptimal culture media than zygotes from non-transgenic (control) mice. The effects of injection of donor mice with gamma-glutamylcysteinyl ethyl ester (gamma-GCE) on embryonic development were also investigated. In addition, the effects of genetic background (i.e., transgenic vs. non-transgenic) and injection with gamma-GCE on developmental capacity in kSOM were studied after exposure of zygotes to diamide (0.01 mM, for 30 min). When cultured in modified Medium 16 significantly more pronuclear ova from transgenic females reached the morula (M) and early blastocyst (EB) stages than embryos derived from control mice. Genetic background significantly affected the proportions of embryos reaching 4- to 16-cell, M and EB stages during culture in modified Whitten's medium (WM); more zygotes collected from transgenic than from control mice developed. The injection of experimental mice with gamma-GCE significantly increased proportions of zygotes developing to M and EB stages in WM. Following exposure to diamide and subsequent culture in kSOM significantly more zygotes collected from transgenic mice reached the 4- to 16-cell stages than those from control females; a significant positive effect on developmental capacity was also seen after injection of donor mice with gamma-GCE. When cultured in suboptimal conditions, zygotes derived from transgenic mice overexpressing glutathione synthetase were more capable of developing than zygotes of non-transgenic control females. Zygotes from the transgenic mice also exhibited greater capacity to withstand toxic exposure to diamide. Present data suggest that commonly known strain differences in preimplantational development in vitro may reflect differences in the synthesis and/or metabolism of glutathione. J. Exp. Zool. 286:173-180, 2000.