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DNA SYNTHESIS IN THE FERTILIZING HAMSTER SPERM NUCLEUS: SPERM TEMPLATE AVAILABILITY AND EGG CYTOPLASMIC CONTROL
Citation:
Naish, S., S. Perreault, A. Foehner, AND B. Zirkin. DNA SYNTHESIS IN THE FERTILIZING HAMSTER SPERM NUCLEUS: SPERM TEMPLATE AVAILABILITY AND EGG CYTOPLASMIC CONTROL. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-87/051 (NTIS PB87212809).
Description:
To assess the role of sperm template availability in the regulation of DNA synthesis, the morphological status of the fertilizing hamster sperm nucleus was correlated with its ability to synthesize DNA after in vivo and in vitro fertilization. Fertilized hamster eggs were incubated in (3)H-thymidine for varying periods before autoradiography. None of the decondensed sperm nuclei nor early (Stage I) male pronuclei present after either in vivo or in vitro fertilization showed incorporation of label, even in polyspermic eggs in which more advanced pronuclei were labeled. In contrast, medium-to-large pronuclei (mature Stage II pronuclei) consistently incorporated (3)H-thymidine. To investigate the contribution of egg cytoplasmic factors to the regulation of DNA synthesis, the authors examined the timing of DNA synthesis by microinjected sperm nuclei in eggs in which sperm nuclear decondensation and male pronucleus formation were accelerated experimentally by manipulation of sperm nuclear disulfide bond content. (Copyright (c) Biology of Reproduction 36, 245-253 (1987).)