Ross M H, Cochran D G
J Hered. 1975 Mar-Apr;66(2):79-88. doi: 10.1093/oxfordjournals.jhered.a108586.
Two new reciprocal translocations in the German cockroach have been analyzed. They were identified cytologically to be T(3;12) and T(7;12). Linkage studies showed that groups XI, IX, and IV are on chromosomes 12, 3, and 7, respectively, and clearly demonstrated sex differences in recombination. Each of these chromosomes have distinctive morphological features that facilitate their identification, and permit breakpoint and centromere localization. A sex difference in fecundity is associated with T(7;12), but not T(3;12). About 40 percent mortality occurred when T(3;12) males or females and T(7;12) females were outcrossed. Outcrossing T(7;12) males produced the expected 50 percent mortality. Cell counts at metaphase I revealed that T(3;12) males exhibit directed segregation, while T(7;12) males do not. Tests for homozygosity indicated that the T(7;12) homozygote is viable. A map of chromosome 12 is presented showing the tentative placement of linkage group XI with respect to interchange breakpoints and chromosome morphology. The results are discussed in relation to possible sex differences in chiasma localization.
对德国小蠊的两个新的相互易位进行了分析。通过细胞学鉴定它们为T(3;12)和T(7;12)。连锁研究表明，第十一组、第九组和第四组分别位于第12、3和7号染色体上，并清楚地显示了重组中的性别差异。这些染色体中的每一条都有独特的形态特征，便于识别，并能确定断点和着丝粒的位置。繁殖力的性别差异与T(7;12)有关，但与T(3;12)无关。当T(3;12)的雄性或雌性与T(7;12)的雌性进行杂交时，约有40%的死亡率。T(7;12)的雄性杂交产生了预期的50%的死亡率。中期I的细胞计数显示，T(3;12)的雄性表现出定向分离，而T(7;12)的雄性则没有。纯合性测试表明，T(7;12)纯合子是可行的。给出了第12号染色体的图谱，显示了连锁群XI相对于互换断点和染色体形态的暂定位置。讨论了与交叉定位中可能的性别差异相关的结果。
