FACTORS AFFECTING THE ROLE OF THE SPINDLE DURING EARLY RESPONSE OF MOUSE OOCYTES TO ETHANOL STIMULATION

Winston et al. ([1995] J. Cell Sci., 108:143-151) have shown recently that short (6 min) exposure of spindle intact oocytes from Swiss mice to 8% ethanol induced activation of most oocytes, while disruption of the spindles in these oocytes by nocodazole, before and during ethanol exposure, completely inhibited oocyte activation. We compared the act ivation rates (ARs) of nocodazole-treated and intact oocytes recovered from SJL and B6D2 F1 hybrid mice under the same experimental conditio ns. The difference between the ARs of nocodazole-treated and intact SU oocytes was about the same as reported for Swiss oocytes (2% vs. 82%, respectively). In contrast, this difference was minor for B6D2 oocyte s (87% vs. 100%, respectively). Moreover, 41% of these oocytes underwe nt activation when the spindle was absent, not only before and during, but also 2 h after ethanol exposure. Shortened exposure (2 min) of B6 D2 oocytes to ethanol, however, increased the difference in the ARs of nocodazole-treated and intact oocytes (18% vs. 67%, respectively). We conclude that at least two parameters affect the necessity of the pre sence of the spindle during ethanol exposure for the activation of mou se oocytes. They are the genotype of the oocytes and the duration of e xposure to ethanol. Under one set of these parameters the presence of the spindle is absolutely necessary, while under the other the appeara nce of the spindle a few hours after ethanol exposure is sufficient to allow the activation of some oocytes. (C) 1996 Wiley-Liss, Inc.