1998 Fiscal Year Final Research Report Summary
An analysis on nuclear differentiation and the continuity of germ line during conjugation of Paramecium caudatum
| Project/Area Number |
08680785
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Developmental biology
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| Research Institution | MIYAGI UNIVERSITY OF EDUCATION |
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Principal Investigator |
MIKAMI Kazuyuki Miyagi University of Education Faculty of Education Professor, 教育学部, 教授 (90091777)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Ciliate / Paramecium / Conjuation / Nuclear differentiation / Germ line / Sexual phase / Lectin / Microinjection |
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| Research Abstract |
Each cell of Paramecium caudatum has a germinal micronucleus and a somatic macronucleus. During sexual phase, a fertilization is produced by fusion of a female and a male pronucluei derived from meiotic products of the micronucleus. The fertilization nucleus divides 3 times and gives rise to produce new macronuclei and micronuclei. Meantime, the prezygotic macronucleus fragments and degenerates later on. Thus, germ line continued by the micronucleus. In the present work, the following results were obtained with the behavior of the micronucleus.
1) The micronucleus at gametogeneisis and fertilization is indispensable for the postconjugationa stomatogenesis. According to the analysis of nulisomic micronuclei, the function on the stomatogenesis is not due to a few specific genes of the micronucleus. Therefore, the possible hypothesis is that the micronucleus has a role to support the organizing center for postconjugational stomatogenesis. The results investigated by the anti-alpha-tubulin antibody showed evidences that the micronuclear behavior was closely related with the dynamics of microtubics.
2) Degeneration process of the meiotic products was followed by electron microscopy. A lectin WGA prevented this degeneration when it was injected into cells (1mg/ml, ca. 35pl) at the stage of 4 nuclei. When WGA-Gold conjugate was injected in the cells, the gold particles appeared at the lysosome like structures. WGA seems to bind directly or indirectly to the cytoplasmic factor to generate the nuclei and prevented them from degenerating.
3) In the exconjugants, there are 4 presumptive micronuclei. At postzygotic cell divisions, only one of them divided and other 3 did not.
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