标题：The frequency of meiotic recombination in yeast is independent of the number and position of homologous donor sequences: implications for chromosome pairing.
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：4
页码：1120-1124
DOI：10.1073/pnas.88.4.1120
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We constructed diploids of Saccharomyces cerevisiae homozygous for LEU2 and carrying one, two, or four copies of leu2 at ectopic locations and determined the frequency of 3+:1- (LEU2:leu2) meiotic tetrads. Gene conversion between a LEU2 recipient and a leu2 ectopic donor occurred at the same frequency as did gene conversion between allelic copies of LEU2 and leu2. An increase in the number of possible ectopic donor loci did not lead to a proportional increase in the level of ectopic gene conversion. We suggest that the limiting step in meiotic recombination is the activation of a locus to become a recipient in recombination and that once activated, a locus can search the entire genome for a homologous partner with which to recombine. In this respect, this search for a homologous partner resembles the efficient premeiotic methylation/inactivation of duplicated sequences in Ascobolus and Neurospora. These observations support models in which strand exchange serves to align homologous chromosomes prior to their becoming much more fully synapsed by the elaboration of the synaptonemal complex.
