Meeting Abstract

P1.51  Tuesday, Jan. 4  The role of Wnt and Decapentaplegic signaling on postembryonic leg development and lipid homeostasis in the flour beetle Tribolium castaneum . NAMIGAI, E.K.**; SHAH, M.V.; SUZUKI, Y.; Wellesley College; Wellesley College; Wellesley College ysuzuki@wellesley.edu

Holometabolous insects undergo complete metamorphosis, a developmental event characterized by striking changes in morphology. While many holometabolous insects develop their adult legs from imaginal discs, the more basal holometabolous insects develop their adult appendages from larval legs. Much is known about the mechanism of imaginal disc formation in highly derived insects, such as the model organism Drosophila melanogaster, but the mechanism governing larval to adult leg development in more basal insects is not well understood. To investigate the mechanism underlying larval to adult leg transformation in basal insects, leg development in the flour beetle, Tribolium castaneum, was examined. It is known that in D. melanogaster, leg growth and proliferation are initiated within imaginal discs, which form at the intersection of two secreted morphogens, Wingless (Wg) and Decapentaplegic (Dpp). However, little is known about the role that these morphogens play during adult leg development in T. castaneum. In this study, the functions of the canonical Wnt signaling pathway and the TGF-β family member dpp were investigated during larval-to-adult leg transformation in T. castaneum. Knockdown of the β-catenin homolog Armadillo (Arm) resulted in severely attenuated adult legs, and Dpp knockdown resulted in adult appendage malformation, strongly suggesting that both Arm and Dpp are key regulators of postembryonic leg development. Unexpectedly, in addition to the effects on leg development, dpp double-stranded RNA injection also resulted in severe fat body loss and body clearing. This curious result indicates that dpp is not only needed for adult leg development but also plays a role in fat metabolism.