繊毛虫Hemicycliostyla Sphagniの二分裂における多数大核の行動

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Several stocks of multi-macronucleated Hemicycliostyla sphagni were isolated after excysting the cysts attached to dry rice-stubbles from various paddy fields. The cells were grown at 23℃ in a wheat-lettuce infusion containing Bodo sp. as a food. Under our conditions, generation time was about 24 hours. In the present studies, a serial change of the macronuclei was investigated during the cell cycle. At 3 hours after cell division each cell possessed 64 (50-68) smallest macronuclei which were equal to micronuclei in terms of size and staining features. After about 12 hours, 5-12 basophilic vacuoles regarded as nucleoli were developed within each smallest macronucleus, but not in the micronucleus. At 15 hours after the separation of daughter cells, a replication band for DNA synthesis began to appear in each macronucleus. Such DNA synthesis occurred for about 5 hours. After disappearance of replication bands, the macronuclei fused with one another and formed a single large mass within 1 hour. About 3 hours before the next cell division (just after fission), amitotic division of the large macronucleus occurred 6 times without being accompanied by DNA synthesis and concurrent cytokinesis, resulting in a production of multiple smaller macronuclei (about 64). After cytokinesis occurred, the smaller macronuclei further divided once within 3 hours. The cell thus possessed about 64 (50-68) smallest macronuclei. Since such smallest macronucleus seems to be equivalent to the diploid micronucleus, the author considers that ploidy of the macronuclei in G-1 cell is about 128n and that in G-2 cell is about 256n. Such a macronuclear behavior during the cell cycle held true for all stocks examined, except that some of the stocks differed in ploidy and in times of consecutive macronuclear division prior to cytokinesis.
社団法人日本動物学会の論文
1972-01-15

著者

高橋忠夫
広島大学理学部動物学教室

繊毛虫Hemicycliostyla Sphagniの二分裂における多数大核の行動

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