[A SC35-like protein is localized in the nucleus of Physarum polycephalum].

ABSTRACT

After being labeled with an anti-SC35 antibody, the specimens of Physarum polycephalum at S, G2, prophase, metaphase and ana-telophase were observed with an Hitachi electron microscope and gold particles marking the location of the SC35-like protein were mainly found in the nucleus,indicating the existence of a SC35-like protein in it. Judging from the densities of the gold particles in the individual domains of the nucleus, the SC35-like protein was principally located in the nucleolar domain and interchromatin domain during G2 and prophase, and the protein was distributed in the interchromosome domain at metaphase and ana-telophase when the nucleus was disintegrated, suggesting that the nucleolus and interchromatin (interchromosome) domain are the two main locations of the SC35-like protein in the nucleus. Further observations upon the nucleolus revealed that the density of the gold particles in the dense fibrillar component (DFC) of the nucleolus was much higher than that of the fibrillar center (FC), demonstrating that the protein was largely situated in the DFC rather than FC.