Heat-shock response in Xenopus oocytes during meiotic maturation and activation.

After a 60 min heat-shock at 36 degrees C, Xenopus oocytes are still able to accomplish a complete meiotic maturation in response to a progesterone treatment. The 36 degrees C heat-shock applied to maturing oocytes strongly enhances the synthesis of a single heat-shock protein of approx. 70 000 molecular weight (hsp70); after activation with the Ca2+-ionophore A 23187, matured oocytes still display the ability to synthesize hsp70 and to survive a heat-shock. A cycloheximide treatment combined with a heat-shock induces, during the recovery period, the synthesis of two heat-shock proteins, of approx. 70 000 and 83 000 molecular weight.