Hairy Wing-a Duplication in Drosophila Melanogaster.

LARGE proportion of the X chromosome deficiencies maintained A in stock at this laboratory are balanced over In(~)dl-qg, y Hw. When such deficiencies were examined cytologically, it was frequently noticed, especially when the chromosomes were unpaired, that there was some departure from the normal salivary gland chromosome banding of the tip region of the X carrying Hw. Since such material was heterozygous for Hw, which is known to be genetically close to this free or left end of X, it seemed logical to investigate whether the presence of Hw might account for the abnormality observed. Evidence obtained later from duplications for the left end of X gave further support to this theory. Flies carrying duplications obtained from the translocation T(I .4)w 258-18 (DEMXREC and SLIZYNSKA 1937) were phenotypically Hairy wing. This finding suggested that the expression of Hairy wing was due in itself to a duplication for some portion of the X chromosome close to the tip and consequently experiments were planned to determine the presence of such a duplication cytologically and to test its behavior genetically. Following are descriptions of mutants and aberrations which were used in this work. These are adapted from descriptions prepared by C. B. BRIDGES for Drosophila Information Service, No. 9. The mutant character Hairy wing (Hw) was found by C. B. BRIDGES in ~ 9 2 3 as a spontaneous mutation in a y cv tf stock. It has not been possible to separate it by crossing over from y , placing its locus, therefore, at 0.0 k. Males carrying Hw show extra bristles along the wing veins, on the head, affecting especially the occipitals, and on the thorax. Extra hairs also occur on the back of the head and on the pleurae. Females heterozygous for Hw show some extra bristles especially on veins; females homozygous for Hw exhibit a more extreme character than the males. They are not lethal, but their viability is reduced to 80 percent. The rank accorded the character as based on viability and ease of classification is I. The mutant achaete (ac) was found in 1916 by WEINSTEIN (1918) as a spontaneous change in the yellow stock. DUBININ referred to it as scll. It has not been possible to separate it from y, but cytological studies place its locus between y and sc, thus o.o+. On homozygous flies the posterior dorsocentrals are missing, while the anterior dorsocentrals are rarely affected; hairs are usually fewer in the neighborhood of the posterior dorso-