MOLECULAR NATURE OF THE UNSTABLE WHITE-ST ARKA ALLELE

In 1992, Bashkirov et al. described the case of occurrence in line C(1 )RM, yw/0; Dp(1;3) w(vco)/+ of a unique female with light, uniformly c olored eyes. This trait was not inherited together with Dp(1;3) w(vco) but was linked to the X chromosome. We denoted this new allele as whi te-starka (w(str)). It proved to be unstable, demonstrating mutational transitions to other allelic states with frequencies of 10(-3) to 10( -5). Southern blot analysis showed that the w(str) mutation was induce d by an insertion of an unknown sequence with a length approximately e valuated by the authors in 1992 as 7 kb. Using a wider spectrum of res triction endonucleases and a prolonged gel running, we were able to es timate the size of this insertion more precisely. According to our dat a, in the case of w(str) we are dealing with an insertion in the locus white of a sequence 15.1 kb long. As seen from our restriction map of the allele w(str), this insertion does not resemble retroposons with long terminal repeats, but is possibly similar to LINE mobile elements of Het-A and TART types, characteristic for heterochromatin.