Analysis of a novel Drosophila Activin ligand, dActivin2/Alp23B. Y. Funakoshi¹, M. Yang¹, D. Nelson², R. Padgett¹. 1) Waksman Inst, Rutgers Univ, Piscataway, NJ; 2) University College of the Cariboo, Kamloops, British Columbia, Canada.

   Activin signaling pathways are known to function in various contexts, such as cell proliferation, apoptosis, or differentiation, in ways distinctive from other TGF pathways. The Drosophila BMP-like signaling pathway (Dpp), has been well studied, but the functions of the activin pathway have just started to be explored. The core of the activin signaling pathway has been defined (type I receptor, Babo, type II receptor, Punt and Wit, and the R-Smad, dSmad2). However, there are two activin-like ligand homologues in the Drosophila genome, but the function of them has not been described due to the lack of mutant strains. We conducted a P element imprecise excision of the genomic region containing dActivin2 and obtained several dActivin2 mutants. They are homozygous lethal and escaper larvae exhibit a delay in development. Further efforts are being directed toward phenotypic analysis of these mutants.