Surosky R T, Tye B K
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
Genetics. 1988 Jun;119(2):273-87. doi: 10.1093/genetics/119.2.273.
We explored the behavior of meiotic chromosomes in Saccharomyces cerevisiae by examining the effects of chromosomal rearrangements on the pattern of disjunction and recombination of chromosome III during meiosis. The segregation of deletion chromosomes lacking part or all (telocentric) of one arm was analyzed in the presence of one or two copies of a normal chromosome III. In strains containing one normal and any one deletion chromosome, the two chromosomes disjoined in most meioses. In strains with one normal chromosome and both a left and right arm telocentric chromosome, the two telocentrics preferentially disjoined from the normal chromosome. Homology on one arm was sufficient to direct chromosome disjunction, and two chromosomes could be directed to disjoin from a third. In strains containing one deletion chromosome and two normal chromosomes, the two normal chromosomes preferentially disjoined, but in 4-7% of the tetrads the normal chromosomes cosegregated, disjoining from the deletion chromosome. Recombination between the two normal chromosomes or between the deletion chromosome and a normal chromosome increased the probability that these chromosomes would disjoin, although cosegregation of recombinants was observed. Finally, we observed that a derivative of chromosome III in which the centromeric region was deleted and CEN5 was integrated at another site on the chromosome disjoined from a normal chromosome III with fidelity. These studies demonstrate that it is not pairing of the centromeres, but pairing and recombination along the arms of the homologs, that directs meiotic chromosome segregation.
我们通过研究染色体重排对减数分裂过程中第三条染色体的分离和重组模式的影响，探索了酿酒酵母减数分裂染色体的行为。在存在一条或两条正常第三条染色体的情况下，分析了缺少一条臂的部分或全部（端着丝粒）缺失染色体的分离情况。在含有一条正常染色体和任意一条缺失染色体的菌株中，这两条染色体在大多数减数分裂中分离。在含有一条正常染色体以及一条左臂端着丝粒染色体和一条右臂端着丝粒染色体的菌株中，这两条端着丝粒染色体优先与正常染色体分离。一条臂上的同源性足以指导染色体分离，并且两条染色体可以被引导与第三条染色体分离。在含有一条缺失染色体和两条正常染色体的菌株中，两条正常染色体优先分离，但在4%-7%的四分体中，正常染色体共分离，与缺失染色体分离。两条正常染色体之间或缺失染色体与正常染色体之间的重组增加了这些染色体分离的概率，尽管观察到了重组体的共分离。最后，我们观察到第三条染色体的一个衍生物，其中着丝粒区域被删除，CEN5整合到染色体上的另一个位点，它与正常的第三条染色体准确分离。这些研究表明，指导减数分裂染色体分离的不是着丝粒的配对，而是同源染色体臂上的配对和重组。
