CYTOLOGY AND GENETICS OF T(9,11) IN THE GERMAN COCKROACH, AND ITS RELATIONSHIP TO OTHER CHROMOSOME 9 TRAITS

Abstract

A new chromosome translocation in the German cockroach, Blattella germanica, was studied. Cytologically, it involves chromosomes 9 and 11 and was designated T(9,11). The approximate positions of the breakpoints were determined. In chromosome 9, the distance between the breakpoint and Df(9)Pw was measured. Genetically, linkage of T(9,11) with the chromosome 9 marker, ru, was estimated at 1.1 ± 0.6%. The new chromosome 9 breakpoint and available linkage data were used to approximate the location of the linkage group on the chromosome. An attempt to correlate map and chromosome distances indicated chromosome 9 probably has a total of at least 50 crossover units.Crosses between T(9, 11) heterozygotes and wild type showed significant sex differences in oothecal size and percent hatch. In males, the hatch data suggested preferential alternate disjunction. This was confirmed cytologically by examination of metaphase I and prophase II cells. In females, the hatch data suggested random disjunction. Similar hatch and cytological data are included for T(9,10)Pw and T(2,11)Cu. Intercrosses of T(9,11) were largely sterile, precluding the attempt to test for a viable homozygote.