Meeting Abstract

P2.135  Saturday, Jan. 5  Examining the role of nitric oxide in the control of molting of the blackback land crab, Gecarcinus lateralis PITTS, NL*; MYKLES, DL; Colorado State University; Colorado State University natalie.pitts@colorado.edu

Nitric oxide (NO) is a unique gaseous signaling molecule involved in variety of biological processes. NO is synthesized from L-arginine, oxygen, and NADPH by nitric oxide synthase (NOS). In decapod crustaceans, we hypothesize that NO modulates the secretion of a neuropeptide, molt-inhibiting hormone (MIH), from the X organ (XO) in the eyestalk ganglia (ESG). Release of MIH from the XO inhibits the synthesis of molting hormones (ecdysteroids) by a pair of Y organs (YOs) in the anterior cephalothorax. A model of MIH signaling involves NO. A reduction in MIH activates the YO, increasing secretion of ecdysteroids and initiating premolt. NOS is expressed in the YO and becomes phosphorylated in the activated YO, reducing the production of NO. NO donors and guanylyl cyclase agonist can inhibit YO ecdysteroidogenesis, suggesting that NO-dependent guanylyl cyclase is a downstream target of the MIH pathway. Eyestalk ablation of intermolt animals up regulates NOS expression in both YO and muscle. The purpose of this study is to determine the effects of molting on the expression of NOS in the YO and ESG. Molting is induced by multiple limb autonomy (MLA) and ESG and YOs are harvested at premolt and postmolt stages. NOS mRNA levels are quantified by Real Time PCR. Localization of NOS uses immunofluorescence. This is the first study to explore the expression of NOS in the ESG and YO over the molt cycle. Supported by NSF (IOS-0745224).