Translocation of dna polymerase-α during the mitotic cycle of Physarum polycephalum

Abstract

The location of DNA polymerase-α within nuclei of a macroplasmodium of Physarum polycephalum was identified at successive stages of the highly synchronous mitotic cycle by indirect immunofluorescence. The distribution of α-tubulin, the nucleolar protein fibrillarin and DNA were also identified. In G2-phase the polymerase-α was found mainly in the region of the nucleolus. In prophase the polymerase became dispersed into the nucleus with the breakdown of the nucleolus. In metaphase, the polymerase-α was located in two zones separated by the metaphase plate. In S-phase, which follows immediately after mitosis, the distribution of the polymerase was initially punctate but later segments were noted during nucleolar reconstruction. We infer that DNA polymerase-α is stored mainly in the region of the nucleolus (or the reconstructing nucleolus) when it is not needed for DNA replication.