Analysis on the nuclear apoptosis indispensable for sexual reproduction in a ciliate, Paramecium.

纤毛虫草履虫有性繁殖所必需的核细胞凋亡分析。

• 批准号: 15603001
• 负责人: MIKAMI Kazuyuki
• 金额: $ 2.3万
• 依托单位: Research Institute on Environmental Education, 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: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15603001/
• 关键词: Paramecium caudatum; macronucleus; micronucleus; nuclear apoptosis; meiosis; germ line; nuclear division; nuclear differentiation; Nuclear apoptosis

Programmed nuclear death occurs in unicellular eukaryotes such as ciliates. In the present work, nuclear apoptosis was investigated from the point of view of nuclear interaction among maternal macronuclei, newly developed macronuclei, maternal micronuclei and newly developed micronuclei. In Paramecium caudatum, programmed nuclear death occurs three times during conjugation (Mikami, 2000).The first of the three selective nuclear degeneration events occurring is the degeneration of meiotic products of the micronucleus. When cells enter the conjugative phase the micronucleus undergoes meiosis and produces four haploid micronuclei. One of these moves into an area called the paroral cone and survives while the other three soon degenerate.The remaining nucleus divides once and produces gametic nuclei (gametogenesis). The gametic micronuclei are exchanged reciprocally between mating cells and form diploid zygotic nuclei. A zygotic nucleus (synkaryon) divides three times to give rise to eight … More nuclei. Four of these differentiate into macronuclear anlagen and the other four became presumptive micronuclei. The four macronuclear anlagen are distributed without nuclear division to daughter cells in two cell divisions after conjugation. For the four presumptive micronuclei, it is known that one remains and the other three degenerate. This is the second nuclear degeneration. The results obtained lead us to a conclusion that most of the micronuclei remained at least by the first post-conjugation fission and that only one of them was selected to divide at the first fission (Taka et al, 2005).The third selective degeneration of nuclei occurs with the parental macronucleus and the macronuclear anlagen (Kimura et al., 2004). After conjugation, the parental macronucleus fragments into pieces that retain the functions of the macronucleus. After several fissions, however, the macronuclear fragments degenerate selectively. If newly developed macronucleus was removed just before the degeneration of macronuclear fragments, the gene expression of the fragments could be reprogrammed to be juvenile (Kimura and Mikami, 2003). Less

程序性核死亡发生在单细胞真核生物如纤毛虫中。本文从母体大核、新生大核、母体微核和新生微核之间的核相互作用的角度研究了细胞核凋亡。尾草履虫在接合过程中发生三次程序性核死亡（Mikami，2000），第一次是微核减数分裂产物的变性。当细胞进入接合期时，微核经历减数分裂并产生四个单倍体微核。其中一个进入口旁锥并存活下来，而其他三个很快退化，剩下的核分裂一次并产生配子核（配子发生）。配子微核在交配细胞间交换，形成二倍体合子核。一个合子核（合核）分裂三次，产生八个 ...更多信息 原子核。其中四个分化为大核原基，其他四个成为假定的微核。四个大核原基在接合后的两次细胞分裂中不经核分裂而分布到子细胞中。对于四个假定的微核，已知一个保留，其他三个退化。这是第二次核变性。获得的结果使我们得出结论，大多数微核至少在第一次接合后分裂时保留，并且在第一次分裂时仅选择其中一个进行分裂（Taka et al，2005）。第三次选择性核变性发生在亲本大核和大核原基中（Kimura et al.，2004年）。接合后，亲本大核分裂成保留大核功能的片段。然而，在几次分裂之后，大核碎片选择性地退化。如果在大核片段变性之前去除新发育的大核，则片段的基因表达可以被重编程为幼年的（Kimura和Mikami，2003）。少

项目成果

Delayed degradation of parental macronuclear DNA in programmed nuclear death of Paramecium caudatum

• DOI: 10.1002/gene.20060
• 发表时间: 2004-09
• 期刊: genesis
• 影响因子: 1.5
• 作者: N. Kimura;K. Mikami;H. Endoh

Interactions between newly developed macronuclei and maternal macronuclei in sexually immature multinucleate exconjugants of Paramecium caudatum.

尾草履虫性未成熟多核外接合子中新发育的大核和母体大核之间的相互作用。

• 发表时间: 2003
• 期刊: Differentiation 71
• 作者: Kimura;K.;Mikami K.
• 通讯作者: Mikami K.

Kimura, K., Mikami, K: "Interactions between newly developed macronuclei and maternal macronuclei in sexually immature multinucleate exconjugants of Paramecium caudatum"Differentiation. 71. 337-345 (2003)

Kimura, K., Mikami, K：“尾草履虫性未成熟多核外接合体中新发育的大核与母体大核之间的相互作用”分化。