Independent chromosome segregation and absence of interchromosomal effect at first meiotic division in male Chinese hamsters heterozygous for two reciprocal translocations

摘要

Chromosome segregation and interchromosomal effects of reciprocal translocations at first meiotic division were investigated by chromosome analysis of meiotic cells from male Chinese hamsters heterozygous for two reciprocal translocations. We used six stocks heterozygous for two different translocations which were obtained by crosses between males and females homozygous or heterozygous for a different translocation. The frequency of second meiotic (MIl) cells from each segregational class of one quadrivalent in heterozygotes for two reciprocal translocations agreed with that of the same quadrivalent in heterozygotes for the single translocation. This indicates that the two quadrivalents in heterozygotes for two reciprocal translocations segregate independently. The mean frequency of hyperhaploid MIl cells from males heterozygous for two reciprocal translocations ranged from 7.1 to 15.4%. These cells were mostly derivatives from 3:1 disjunctions of the quadrivalents. The percentage of cells with extra chromosomes in translocation-unrelated groups was calculated at 0.10–0.25%. The frequency did not increase significantly as compared with that in karyotypically normal males, in which the mean frequency of hyperhaploid MIl cells was 0.39%. These findings revealed that reciprocal translocations do not have interchromosomal effects on meiotic division in male Chinese hamster