SHECHTER, A*; YUDKOVSKI, Y; TOM, M; OPHIR, R; CHALIFA-CASPI, V; CHANG, S.A; CHANG, E.S; SAGI, A; Ben Gurion University of the Negev, Israel; Israel Oceanographic and Limnological Research; Univ of California, Bodega Marine Laboratory: Ecdysteroid-affected genes in endocrinologically-induced molt cycle of the crayfish Cherax quadricarinatus � the use of a cDNA microarray

During premolt in arthropods a surge in ecdysteroid levels triggers a programmed gene expression pattern. To elucidate the pivotal role of 20-hydroxyecdyson (20E), initiation of the molting process has been experimentally induced in the crayfish C. quadricarinatus by either X-organ-sinus gland (XO-SG) removal or administration of exogenous 20E. A 4700 clone C. quadricarinatus cDNA microarray composed of hepatopancreatic transcripts was used during the premolt stage, which was precisely determined through X-ray digital imaging of the gastroliths and ecdysteroid levels. Since both treatments involved ecdysteroid elevation we assumed that genes which are similarly affected by both are suspected to be ecdysteroid triggered. Genes affected exclusively by XO-SG removal are suspected to be triggered by the absence of XO-SG borne neuropeptides. 200 clones showed significant changes in both treatments and were sequenced and annotated. Approximately 100 genes suspected as ecdysteroid-triggered were identified comprising of mostly transport proteins, peptidases and proteins related to chitin and carbohydrate metabolism. 144 clones showing significant changes exclusive to the XO-SG removal treatment were sequenced and annotated. Approximately 90 genes which their expression seems to be related to XO-SG neuropeptides are comprised mostly of integral membrane, nuclear and hypothetical proteins. 20-25% of the genes in both groups showed no similarity to any known genes from the database. This study opens a path for further functional genomic studies of specifically molt induced genes.