Correlation between meiotic behavior and breakpoints with respect to G-bands in two X-4 mouse translocations: T(X;4)7R1 and T(X;4)8R1.
The meiotic synaptic behavior of male mice heterozygous for one of two X-4 translocations was examined to test a recently advanced hypothesis (Ashley, 1988) suggesting that it is possible to predict the synaptic behavior (nonhomologous vs. homologous) and recombinational parameters (suppression vs. nonsuppression of crossing-over) of a chromosome aberration from mitotic G-band breakpoint data. The hypothesis was based on prior observations of synaptic behavior in a series of X-autosome translocations in mice. The breakpoints of the translocation T(X;4)7R1 are both in G-light bands. As predicted by the hypothesis, synapsis was restricted to homology. In contrast, one breakpoint of the translocation T(X;4)8R1 lies in a "stippled" band of the standard diagrams of Nesbitt and Francke (1981). As predicted (Ashley, 1988), "stippled" bands are shown here to synapse nonhomologously, i.e., they behave as "G-dark." The linkage data, as they relate to the synaptic data and the predictions of the hypothesis, are also discussed.
Ashley
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Department of Zoology, University of Tennessee, Knoxville 37996.
Cacheiro
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D000818:Animals; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002875:Chromosomes / Q000502:physiology* / Q000648:ultrastructure; D003434:Crossing Over, Genetic; D008040:Genetic Linkage; D008540:Meiosis; D051379:Mice; D008817:Mice, Mutant Strains; D014178:Translocation, Genetic; D014960:X Chromosome