Biological Institute, Tohoku University, Sendai 980, Japan.
Genetics. 1985 Dec;111(4):779-94. doi: 10.1093/genetics/111.4.779.
Artificially induced intersyngenic crosses in Paramecium caudatum can produce viable and fertile hybrids. When F(1) hybrids of double E mating type (Mt(1)/Mt(3) or Mt(12)/Mt(3)) were crossed with mating type O (mt/mt), aberrant segregants of double E and single O type were produced. This segregation was not explained by ordinary equal or unequal crossing over. Breeding analyses of these segregants by using linkage between Mt and cnrA (a behavioral mutant) revealed that they were produced by meiotic nondisjunction of bivalent chromosomes carrying Mt genes, and thus the double E and single O segregants were aneuploids: trisomics ( Mt(1)/Mt(3)/mt or Mt( 12)/Mt(3)/mt) and monosomics (mt), respectively. An aberrant segregant was also obtained for another locus, tnd 2, independent of both Mt and cnrA, suggesting the occurrence of meiotic nondisjunction throughout hybrid genomes. These aneuploids will be useful for genetic study in this species. The occurrence of meiotic nondisjunction in the intersyngenic hybrids also suggests that syngens of P. caudatum have been reproductively isolated for long enough to develop chromosomal incompatibility in their meiotic process.
人工诱导的聚缩虫属间杂交可以产生可育和可育的杂种。当具有双重 E 交配型（Mt(1)/Mt(3)或 Mt(12)/Mt(3)）的 F(1)杂种与交配型 O（mt/mt）杂交时，产生了具有双重 E 和单一 O 型的异常分离体。这种分离不能用普通的均等或不均等交叉来解释。通过 Mt 和 cnrA（一种行为突变体）之间的连锁对这些分离体进行的繁殖分析表明，它们是由携带 Mt 基因的二价染色体的减数分裂不分离产生的，因此双重 E 和单一 O 分离体是染色体数目异常的非整倍体：三体（Mt(1)/Mt(3)/mt 或 Mt(12)/Mt(3)/mt）和单体（mt），分别。另一个独立于 Mt 和 cnrA 的位点 tnd 2 也获得了一个异常分离体，这表明整个杂种基因组中发生了减数分裂不分离。这些非整倍体将有助于该物种的遗传研究。减数分裂不分离的发生也表明，聚缩虫的 syngens 已经进行了足够长时间的生殖隔离，以在它们的减数分裂过程中发展出染色体不相容性。
