THE DROSOPHILA LIM-ONLY GENE, DLMO, IS MUTATED IN BEADEX ALLELES AND MIGHT REPRESENT AN EVOLUTIONARILY CONSERVED FUNCTION IN APPENDAGE DEVELOPMENT

The process of wing patterning involves precise molecular mechanisms t o establish an organizing center at the dorsal-ventral boundary, which functions to direct the development of the Drosophila wing. We report that misexpression of dLMO, a Drosophila LIM-only protein, in specifi c patterns in the developing wing imaginal disc, disrupts the dorsal-v entral (D-V) boundary and causes errors in wing patterning. When dLMO is misexpressed along the anterior-posterior boundary, extra wing outg rowth occurs, similar to the phenotype seen when mutant clones lacking Apterous, a LIM homeodomain protein known to be essential for normal D-V patterning of the wing, are made in the wing disc. When dLMO is mi sexpressed along the D-V boundary in third instar larvae, loss of the wing margin is observed. This phenotype is very similar to the phenoty pe of Beadex, a long-studied dominant mutation that we show disrupts t he dLMO transcript in the 3' untranslated region, dLMO normally is exp ressed in the wing pouch of the third instar wing imaginal disc during patterning. A mammalian homolog of dLMO is expressed in the developin g limb bud of the mouse. This indicates that LMO proteins might functi on in an evolutionarily conserved mechanism involved in patterning the appendages.