Activation of mouse oocytes requires multiple sperm factors but not sperm PLC gamma 1

A sperm cytosolic factor is responsible for oocyte activation at fertilizat ion in mammals. The molecular identity of this factor is not yet known, alt hough a sperm phospholipase C gamma (PLC gamma) is a potential candidate. I n this study, cation-exchange chromatography with a Heparin column was used for the fractionation of porcine sperm cytosolic extracts. Oocyte activati on potential of the resulting fractions was tested and active fractions wer e subjected to Western blot analysis using antibodies specific to PLC gamma 1. PLC gamma 1 was detected in fractions other than those supporting oocyt e activation (Ca2+-release and pronuclear formation). The active Heparin fr action was then purified on a Mono Q anion-exchange column. One of the resu lting fractions still contained Ca2+-releasing activity, bur pronuclear for mation did not occur. We conclude that sperm PLC gamma 1 is not involved in oocyte activation and that Ca2+-release and pronuclear formation requires multiple factors from sperm cytosol. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.