Actin localization in nuclei of two-cell mouse embryos

In this study, preimplantation mouse embryos were used as a new model for the study of actin distribution in nuclei and the identification of functional forms of nuclear actin. The combination of the direct detection of actin by fluorescent-conjugated phalloidin and DNase I with indirect immunofluorecence was applied as an integrated approach to studying the localization of actin in nuclei of two-cell mouse embryos. Aggregates of monomeric actin and two oligomeric forms of actin were revealed in nuclei. Each of these forms demonstrated their own pattern of distribution. Oligomeric actin recognized by antibodies to the actin C-terminal domain was associated with condensed chromatin, as well as with metaphase chromosomes and chromatin of the second polar body. Monomeric actin and another oligomeric form recognized by antibodies to actin N-terminal domain were revealed in the area of dispersed chromatin localization.