The fate of oocyte nuclear proteins during early development ofXenopus laevis

The localization and movements of four nuclear proteins, originally contained in the germinal vesicle ofXenopus oocytes, were followed through early development from cleavage to late neurula. The study made use of monoclonal antibodies directed against germinal vesicle proteins. Biochemical methods showed that all proteins persist in the embryo without a change in molecular size or gross concentration. At early stages the proteins are localized preferentially in the cytoplasm of the animal hemisphere. They shift from the cytoplasm to the nucleus at stages specific for the individual proteins. During mitosis the proteins are released from the nucleus into the cytoplasm.