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An analysis on nuclear differentiation and the continuity of germ line during conjugation of Paramecium caudatum

尾草履虫接合过程中核分化和种系连续性分析

基本信息

批准号：
08680785
负责人：
MIKAMI Kazuyuki
金额：
$ 1.6万
依托单位：
MIYAGI UNIVERSITY OF EDUCATION
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08680785/
关键词：
Ciliate Paramecium Conjuation Nuclear differentiation Germ line Sexual phase Lectin Microinjection レクテン

项目摘要

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.

尾草履虫的每个细胞都有一个胚性微核和一个体细胞大核。在有性阶段，通过来自微核减数分裂产物的雌性和雄性原核细胞融合产生受精。受精核分裂3次，产生新的大核和微核。同时，合子前的大核在以后发生碎裂和退化，从而使生殖系由微核延续。本研究对微核的行为进行了研究，结果表明：1）配子发生和受精过程中的微核是接合后气孔发生所必需的。通过对核小体微核的分析，认为微核对气孔发生的作用不是由少数特异基因决定的。因此，可能的假设是，微核的作用，以支持组织中心接合后气孔发生。抗α-微管蛋白抗体的检测结果表明，微管的动态变化与微核行为密切相关。2）电镜观察减数分裂产物的退化过程。当将凝集素WGA注射到细胞中时（1 mg/ml，约20 mg/ml），35pl）。当将WGA-金结合物注射到细胞中时，金颗粒出现在溶酶体样结构处。WGA可能直接或间接地与细胞质因子结合，产生细胞核，并阻止细胞核的退化。在合子后细胞分裂时，只有1个细胞分裂，另外3个细胞不分裂。