Potential advantages of unstable interactions for pairing of chromosomes in meiotic, somatic, and premeiotic cells.
Many different aspects of chromosome pairing, meiotic and/or somatic, can be explained conveniently if the interactions between homologous chromosomes are unstable. Initial pairing interactions should involve very unstable contacts. Such interactions could go a long way toward bringing each pair of homologous chromosomes into a joint domain, free of ectopic associations and random entanglements with other chromosomes, and in a topologically acceptable relationship to the domains of other chromosome pairs. More generally, colocalization into topologically acceptable domains could be a useful way of defining the existence of "order" at early stages in pairing; this definition requires that chromosomes have in some way recognized and interacted with one another but does not require that they necessarily be in close apposition and/or that they be aligned along their entire lengths. At later stages, interactions between pairing chromosomes could be unstable but still reversible, either intrinsically or due to an active cell-directed process. Transient homologous interactions could also contribute to maintaining colocalization between homologous chromosomes through DNA replication.
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
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Kleckner
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BM
Weiner
D000818:Animals; D002875:Chromosomes / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D008540:Meiosis / Q000235:genetics*; D008957:Models, Genetic; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000378:metabolism; D015053:Zygote / Q000648:ultrastructure
D004247:DNA; D004250:DNA Topoisomerases, Type II