In an effort to characterize the lethal translucida (l(3)tr) gene, I made crosses between the following stocks 528 l(3)tr1 Sb1/In(3L)P, In(3R)UbxP18, Me1 Ubx1 UbxP18 e4 1918 Df(3R)red-P93, l(3)tr1 Sb1/In(3L)P, In(3R)UbxP18, Me1 UbxP18 e4 and 529 l(3)tr1 Ubx1/TM1 and saw that the resulting homozygous l(3)tr1 larvae showed the bloated phenotype described by Hadorn and Rosin (FBrf0063497). They had mapped l(3)tr1 to 3-20.8 by recombination with ru1 and h1. Using overlapping deletions covering the ru to h interval, I found that l(3)tr1 was lethal in combination with one set of overlapping deletions, but was not lethal in combination with deletions of any other region. (There were three small gaps in deletion coverage surrounding the haploinsufficient genes RpL26, RpL18 and RpL14 that could not be tested.) Specifically, l(3)tr1 was lethal in combination with Df(3L)Exel8104, Df(3L)pbl-X1, Df(3L)BSC375, Df(3L)BSC875 and Df(3L)BSC459. The distal breakpoint of Df(3L)BSC375 and the proximal breakpoint of Df(3L)Exel8104 define the smallest interval containing l(3)tr. The sole transcription unit in this interval is larval translucida (ltl) described by Matt Gibson and colleagues in FBrf0212881, who named it for the similarity of mutants to the published descriptions of lethal translucida mutants. They were not aware that stocks of l(3)tr1 existed. Because Gibson and colleagues have characterized larval translucida mutations molecularly and have examined mutant phenotypes extensively and because other studies have built on their work, I suggest that l(3)tr1 be renamed as an ltl allele despite the historical precedence of the lethal translucida gene name. Kevin R. Cook, Ph.D. Bloomington Drosophila Stock Center Department of Biology Indiana University
