Immunolocalization of HSP 70-related proteins constitutively expressed during Xenopus laevis oogenesis and development.

Using immunocytochemical and biochemical methods, we analyzed the localization of HSP 70-related proteins constitutively expressed during oogenesis 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 maintained from fertilization up to late blastula. It is noteworthy that, at the beginning of gastrulation, nuclear transfer of such proteins had already occurred by the time of internalization in the involuting marginal zone (IMZ), whereas cells of the vegetal area exhibited only a perinuclear localization of these proteins. These results suggest that HSP 70-related proteins might be involved in the control of the process of cellular internalization.