Protein Synthesis during Photocontrolled Progression of the Cell Cycle in Single-celled Protonemata of the Fern Adiantum Capillus-veneris |
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Authors: | AKIRA NAGATANI HIDEHO SUZUKI MASAKI FURUYA |
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Institution: | Department of Biology, Faculty of Science, University of Tokyo, Hongo, Tokyo 113, Japan |
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Abstract: | Protein synthesis during photoinduced, synchronous progression of the cell cycle in single-celled protonemata of the fern Adiantum capillus-veneris was studied by tracer techniques. Nuclei of the protonemata were labelled with 3H-thymidine during spore germination so that the amount of 3H incorporated into the TCA-insoluble fraction of the cells could be used as a measure of the cell number in each sample. The rate of the incorporation of 14C-amino acids into TCA-insoluble materials was not significantly varied at different stages of the cell cycle or by treatment with blue light. Extracts of cells labelled with 35S-methionine at various times after the transfer from red light condition (G0) to darkness (G1 to S) were analyzed by two-dimensional gel electrophoresis. At least 3 of about 200 spots showed significant changes in intensity on fluorograms. Spot A (molecular weight 20,000, isoelectric point 6.3) was detectable only in early G1, whereas spot B (molecular weight 19,500, isoelectric point 6.3) was found only in the late G1 and S phases. When the cells were exposed to blue light before the dark incubation, the times of disappearance of spot A and appearance of spot B were advanced depending upon the progression of the cell cycle but not upon the clock time. |
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