Meeting Abstract

P3.40  Saturday, Jan. 5  Increased nitric oxide synthase expression in the activated molting gland of the land crab Gecarcinus lateralis MCDONALD, Audrey A.*; BADER, Brandon D.; COVI, Joe A.; MYKLES, Donald L.; Colorado State University, Fort Collins; Colorado State University, Fort Collins; Colorado State University, Fort Collins; Colorado State University, Fort Collins audmcdon@simla.colostate.edu

Molting in crustaceans is regulated ecdysteroids produced in the Y-organs (YO) located in the lateral cephalothorax. Ecdysteroid secretion by the YO is suppressed in the presence of molt-inhibiting hormone (MIH), a neuropeptide produced in the X-organ of the eyestalk ganglia (EG). The binding of MIH to its cell surface receptor in the YO activates a signal transduction cascade, resulting in decreased production of ecdysteroids. Recent research indicates that the pathway may involve nitric oxide synthase (NOS), an enzyme which catalyzes the production of nitric oxide from oxygen and arginine and is known to be present in the YO. Additional research shows that the sensitivity of the YO to MIH varies over the molting cycle. To illuminate the role of NOS, we eye stalk ablated (ESA) land crabs, effectively removing the endogenous source of MIH and quantified NOS expression levels in the YO from intact and 1, 3 and 7 days post ESA animals. Total mRNA was isolated from excised YOs, and cDNA synthesized via reverse transcription. NOS cDNA was then quantified using real-time PCR. Results indicate a significant increase in NOS expression over seven days in the absence of MIH. Quantification of ecdysteroid levels in hemolymph by radioimmunoassay also indicate a significant increase in ecdysteroid concentration seven days post ESA. Supported by National Science Foundation. (IBN-0342982)