[A cyclin A-like protein is localized in the cells of Physarum polycephalum and functions in the cell cycle].
The subcellular distribution of a Cyclin A-like protein in the cells of Physarum polycephalum and the function of the protein in the cell cycle were studied by immunoelectron microscope and anti-Cyclin A antibody blocking. After labeled with an anti-Cyclin A monoclonal antibody, the density of gold particles in the labeled specimens was much higher than that in the control, indicating that a Cyclin A-like protein existed in Physarum polycephalum. In the labeled specimen, the gold particles density of the nucleus was higher than that of cytoplasm, which was similar to that of the control, demonstrating that the Cyclin A-like protein was a nuclear protein. The gold particles density of the nuclei varied during the cell cycle. The highest appeared in S phase and the lowest came in metaphase and ana-telophase, which was close to that in the control. From S phase to metaphase, the gold particle densities dropped down gradually. The changes in the gold particle density showed the changes in the content of the Cyclin A-like protein. After treated with the anti-Cyclin A antibody in S phase and G2 phase respectively, the nuclei of Physarum polycephalum were arrested in the phases and the morphology of these nuclei became irregular. When treated with the anti-Cyclin A antibody in prophase, the nuclei appeared abnormal. These results suggested that the Cyclin A-like protein is important in cell cycle regulation of Physarum polycephalum, essentially in S/G2 and G2/M changes.
Li
Xiao-Xue
XX
Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China.
Li
Gui-Ying
GY
Xing
Miao
M
D000818:Animals; D002453:Cell Cycle; D019925:Cyclin A / Q000032:analysis* / Q000502:physiology; D016253:Microscopy, Immunoelectron; D016839:Physarum polycephalum / Q000737:chemistry*
D019925:Cyclin A