Meeting Abstract
P1.60 Saturday, Jan. 4 15:30 Understanding hormone release by analyzing gene expression in the eyestalk throughout the molt cycle of the green crab, Carcinus maenas SCHULZ, H.M.*; PITTS, N.L.; MYKLES, D.L.; Colorado State University ; Colorado State University ; Colorado State University hmschulz@rams.colostate.edu
In decapod crustaceans, molting is regulated by the release of MIH from the X-organ/sinus gland (XO/SG) complex in the eyestalk ganglia (ESG). Neuropeptide synthesis occurs in the XO and includes the production of crustacean hyperglycemic hormone (CHH), as well as a molt-inhibiting hormone (MIH). CHH is a neuropeptide that is important in the regulation of various physiological functions including hyperglycemic action and other metabolic functions. MIH negatively regulates molting by inhibiting the Y-organ or molting gland. We hypothesize that the signaling molecule nitric oxide (NO) is involved in the secretion of neuropeptides from the SG. NO is synthesized by NO synthase (NOS) by catalyzing the conversion of L-arginine to L-citrulline. NO binds to a receptor guanylyl cyclase (GC-Iβ). Previous work showed that MIH and CHH mRNA levels are the same in the XO from intermolt (stage C4) and premolt (stage D2) animals. This suggests that control of neuropeptide release from the SG is posttransciptional. We hypothesize that NO acts as a neuromodulator by suppressing synaptic vesicle binding to the cell membrane, thus reducing neuropeptide release from the SG. The decrease in MIH stimulates molting. The purpose of this study is to examine whether NO is involved in the release of MIH and CHH from the SG. qPCR is utilized to quantify the expression of MIH, CHH, NOS, and GC-Iβ throughout the molt cycle in the ESG. Primers were designed to reduce dimerization and secondary structure formation. RNA was purified from ESG harvested from animals at intermolt, premolt, and postmolt stages. Cm-EF2 endpoint PCR was used to evaluate the cDNA. The experiments are currently in progress and the results will be reported. Supported by NSF (IOS-1257732).
