THE HSR CHROMOSOME-1 IN THE HOUSE MOUSE, MUS MUSCULUS, FROM REGIONS OF THE URALS POLLUTED BY MUTAGENS

The incidence of the HSR chromosome 1 was examined in Mus musculus mus culus from 12 localities of the Middle and South Urals and Northwester n Siberia. The HSR chromosome was found in 7 localities, its frequency varying from 5 up to 18%. The HSR incidence was shown ro correlate wi th the mean pooled frequency of aneuploidy and polyploidy in bone marr ow, but not with the mean proportion of cells carrying structural chro mosome aberrations. In mice heterozygous for HSR the rate of aneuploid y and polyploidy was significantly higher than in animals with standar d karyotype, on average by a factor 2.35. HSRs tend to be more abundan t in localities adjacent to sites of radiation incidents with contamin ation mainly by Sr-90.