Komori Rie, Harumoto Terue, Fujisawa Hiromi, Takagi Yoshiomi
The Division of Human Environmental Sciences, Graduate School of Human Culture, Nara Women's University, Nara, Japan.
Zoolog Sci. 2002 Nov;19(11):1245-9. doi: 10.2108/zsj.19.1245.
Autogamy in Paramecium tetraurelia is a form of sexual reproduction in a single cell that results in homozygosity in every genetic locus. Autogamy becomes inducible by natural starvation several fissions after the previous autogamy, and percent autogamy increases gradually with clonal age to reach 100%. We here report the degree of variability of the autogamy-maturation pattern, and how it is inherited through autogamous generations. We assessed the autogamy-maturation pattern by monitoring percent autogamy at the ages of 9, 18 and 27 fissions in the wild-type stock 51. To determine how the autogamy-maturation pattern is inherited, clones that showed the lowest and the highest percent autogamy at age 18 in a given autogamous generation (Gn) were examined for their percent autogamy in the next autogamous generation (Gn+1). This procedure was repeated through successive autogamous generations. We found that percent autogamy at ages 9 and 27 was rather stable (low and high, respectively), while it was extremely variable at age 18 ranging from 3% to 100%. We also found that percent autogamy at age 18 in the progeny clones was variable irrespective of percent autogamy at age 18 in the parental clones; there was no regular rule such as producing progeny with higher (or lower) percent autogamy from parents with lower (or higher) percent autogamy.
四膜虫的自体受精是单细胞中的一种有性生殖形式，会导致每个基因座都出现纯合性。在前一次自体受精后的几次分裂后，自然饥饿可诱导自体受精，并且自体受精的比例会随着克隆代数的增加而逐渐上升至100%。我们在此报告自体受精成熟模式的变异程度，以及它如何在自体受精的世代中遗传。我们通过监测野生型51品系在第9、18和27次分裂时的自体受精比例来评估自体受精成熟模式。为了确定自体受精成熟模式是如何遗传的，我们检查了在给定的自体受精世代（Gn）中18次分裂时自体受精比例最低和最高的克隆在下一代自体受精世代（Gn+1）中的自体受精比例。这个过程在连续的自体受精世代中重复进行。我们发现，9次和27次分裂时的自体受精比例相当稳定（分别为低和高），而18次分裂时的自体受精比例变化极大，从3%到100%不等。我们还发现，子代克隆在18次分裂时的自体受精比例是可变的，与亲代克隆在18次分裂时的自体受精比例无关；不存在诸如从自体受精比例较低（或较高）的亲代产生自体受精比例较高（或较低）的子代这样的规律。
