Aufderheide K J, Schneller M V
Mech Ageing Dev. 1985 Nov;32(2-3):299-309. doi: 10.1016/0047-6374(85)90087-9.
The aging characteristics of various known mutations of Paramecium tetraurelia have been studied. Among the mutations which had been previously isolated on the basis of the inability of the cell to do exocytosis of its trichocysts, one group was identified which had clonal life spans which were indistinguishable from, or were somewhat shorter than, the life span of wild-type. Another group of trichocyst mutations, however, had clonal life spans which were 1/3 to 1/4 that of wild-type. Further study of the phenotypes of these various mutations revealed that members of the short-lived group all had a common phenotypic defect: a frequent inability to properly divide the macronucleus during cell division. Another mutation which has normal trichocysts, but which shows macronuclear division defects, also has an extremely short life span. Thus, the short clonal life spans seen are not associated with the inability to do trichocyst exocytosis but rather are associated with the inability to properly divide the macronucleus. An hypothesis is presented which relates macronuclear misdivision to the short clonal life spans of the mutants expressing it. By extension of the hypothesis, the significance of normal macronuclear divisions to the normal aging process in P. tetraurelia is proposed.
人们已经对草履虫各种已知突变的衰老特征进行了研究。在之前基于细胞无法进行刺丝泡胞吐作用而分离出的突变中，鉴定出了一组克隆寿命与野生型无差异或略短于野生型的突变。然而，另一组刺丝泡突变的克隆寿命仅为野生型的1/3至1/4。对这些不同突变的表型进行进一步研究发现，寿命较短的那组突变体都有一个共同的表型缺陷：在细胞分裂过程中频繁无法正常分裂大核。另一个具有正常刺丝泡但表现出大核分裂缺陷的突变体，其寿命也极短。因此，观察到的较短克隆寿命并非与无法进行刺丝泡胞吐作用相关，而是与无法正常分裂大核有关。本文提出了一个假说，将大核错误分裂与表达该现象的突变体的短克隆寿命联系起来。通过对该假说的拓展，提出了正常大核分裂对四膜虫正常衰老过程的重要性。
