Nucleosome unit repeat size in aneuploid mice.

Male 8-day-old mice that have part of chromosome 7 translocated to an X chromosome [T(X;7)1 Ct] and that are chromosomally unbalanced for chromosome 7, and consequently trisomic for that part of chromosome 7, were found to have a smaller nucleosome repeat unit size than normal littermate males (Rake, A. V., and Edwards, R. H., Biochem. Genet. 25:671, 1987). This smaller nucleosome size is maintained in adult trisomic males. Males with a balanced chromosomal translocation [T(X;7)1Ct] had a normal nucleosome size compared to their littermates. The nucleosome unit size is not altered in two other types of aneuploid mice studied (XO vs XX, 2n = 39 and 40, respectively; and Ts12(17) vs normal, 2n = 40 and 41, respectively).