IMMUNOLOCALIZATION OF HSP 70-RELATED PROTEINS CONSTITUTIVELY EXPRESSED DURING XENOPUS-LAEVIS OOGENESIS AND DEVELOPMENT

Using immunocytochemical and biochemical methods, we analyzed the loca lization of HSP70-related proteins constitutively expressed during oog enesis and embryogenesis in the amphibian Xenopus laevis. Our results provided evidence for a regional localization in oocytes. In embryos, the regional distribution observed in oocytes was found to be maintain ed from fertilization up to late blastula. It is noteworthy that, at t he beginning of gastrulation, nuclear transfer of such proteins had al ready occurred by the time of internalization in the involuting margin al zone (IMZ), whereas cells of the vegetal area exhibited only a peri nuclear localization of these proteins. These results suggest that HSP 70-related proteins might be involved in the control of the process o f cellular internalization.