CONDITIONS FOR A HEAT-SHOCK RESPONSE DURING OOGENESIS AND EMBRYOGENESIS OF THE AMPHIBIAN PLEURODELES WALTL

The optimal conditions capable of inducing an increase in HSP70 neosyn thesis during development of the urodele amphibian Pleurodeles waltl w ere determined in this study. These conditions depend on temperature, heat shock duration and recovery duration. In oocytes, a heat shock re sponse was repeatedly obtained at 37 degrees C for 15 min followed by 1 h recovery, These results provided evidence for heat shock response at every stage considered. An increase in HSP70 synthesis was noted th roughout oogenesis, but it did not lead to an increase in the amount o f soluble HSP70, except for stage VI oocytes. Such results suggest tha t from stage II to stage IV oocytes, an equilibrium occurs between the HSP70 used and the HSP70 neosynthesized. in contrast, in stage VI ooc ytes, heat shock led to overproduction of HSP70. During early developm ent, the heat shock response was repeatedly obtained only from the gas trula stage with a 37 degrees C, shock and a 15 min duration of treatm ent. Surprisingly during cleavage stage, the soluble HSP70 total amoun t increased after heat shock at a time when no HSP70 neosynthesis occu rred.