Identification by quinacrine fluorescence of the chromosome carrying mouse linkage group I in the Cattanach translocation.

ATTANACH's flecked ( fd ) translocation, T( I ;X)Ct is thought to be a 3-point nonreciprocal translocation in which an inverted segment (SLrzYNsKI 1967) of the mid-portion of linkage group I (LG I, EICHER 1967) has been inserted into the mid-portion of the X (CATTANACH 1966). One of the break points in LG I is between the sh-1 and Hbb loci (EICHER 1967; WOLFE 1967). The second break point is between the qu and ru-2 loci. The length of the segment of LG I which has been inserted into the X is thus 21-32 centimorgans (cM) long, i.e. 30-46% of the 70 CM distance separating the outside markers of LG I, fr and nu (MNL 1970). It is now possible to identify each chromosome in the mitotic metaphase complement of the mouse by its quinacrine fluorescence pattern (MILLER, et al. 1971). Using this technique, we have identified the X and Y chromosomes and numbered each pair of autosomes in order of their approximate length. Using a series of translocations, we have been able to assign LG I1 to chromosome 10, LG I11 to 12 or 15, LG IX to 16, LG XI to 6, LG XI1 to 19, and LG XI11 to 1. We report here the assignment of LG I to chromosome 8 and confirmation of our earlier identification of the X (by definition, LG XX) by quinacrine fluorescence study of the Cattanach translocation.