CORRELATION BETWEEN MEIOTIC BEHAVIOR AND BREAKPOINTS WITH RESPECT TO G-BANDS IN 2 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-auto-some 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. © 1990 S. Karger AG, Basel.