The Genetics of Dopa Decarboxylase in Drosophila Melanogaster. IV. The Genetics and Cytology of the 37B10-37D1 Region

Of 204 mutations located in the 8-12 band Df(2L)130 region, 37B9-C1,2;37D1-2, 199 have been assigned to twelve lethal genes and one visible gene (hook). The 13 genes are not evenly distributed. Twelve, (possibly all thirteen) are in the seven band region 37B10-C4 giving a gene-to-band ratio of almost two. Only one gene, 1(2)37Cf, may be in the four band region 37C5-7, and none are localized in band 37D1. In situ hybridization places the dopa decarboxylase structural gene, Ddc, in or very close to band 37C1,2 (Hirsh and Davidson, 1981). The chi methyl dopa hypersensitive gene, 1(2) and, is 0.002 map units distal to Ddc. Df(2L)VA17, 37C1,2; 37F5-38A1 may actually break in the 37C1,2 singlet. It places six genes, hook, 1(2) and, and four lethal genes, in a maximum of five bands, 37B10, 11, 12, 13 and perhaps part of the 37C1,2 singlet and localizes six genes, Ddc plus five lethal genes, in a maximum of three bands; probably part of the 37C1,2 singlet plus bands, C3, and C4. Wild type activity of five of twelve lethal genes is necessary for female fertility. --Band 37C5 puffs at the time of pupariation; Puff Stages 8-10. Twelve of eighteen alleles of 1(2)37Cf have been examined as heterozygotes over CyO and none affect the appearance of a homozygous 37C5 puff. --Of the 204 mutations considered here only one Ddcpl, affects the function of more than one gene. It eliminates Ddc+ and 1(2)37Ca+ function and at 30 degrees C reduces 1(2)37Ce+ function. It is not a deficiency but could be a polar mutant.