P1.59 Wednesday, Jan. 4 Effects of molting on myostatin expression in crustacean skeletal muscle COSENZA, K. S.*; SORACH, K.; CHANG, E. S.; MYKLES, D. L.; Colorado State Univ; Colorado State Univ; UC Davis Bodega Marine Lab; Colorado State Univ email@example.com
In response to molting hormone (ecdysteroid), claw muscle atrophies to ease withdrawal at ecdysis. In blackback land crab, Gecarcinus lateralis, molting can be induced by eyestalk ablation (ESA) or multiple leg autotomy (MLA). Limb bud autotomy (LBA) suspends premolt by lowering hemolymph ecdysteroid titer. During premolt, down-regulation of myostatin (Gl-Mstn) is associated with increased protein synthesis during myofibril remodeling. Gl-Mstn levels are negatively correlated with ecdysteroid levels, suggesting that ecdysteroids inhibit Gl-Mstn expression. In thoracic muscle, which does not atrophy, Gl-Mstn mRNA and ecdysteroid are not correlated. The difference in response to ecdysteroids may be due to differences in ecdysteroid receptor (RXR/EcR) isoforms. The main goal is to determine how ecdysteroids control Mstn expression in G. lateralis and in Carcinus maenas. In G. lateralis, suspension of premolt by LBA maintained Gl-Mstn at elevated levels, which is consistent with the hypothesis. The effects of 20-hydroxyecdysone (20E) injection on Gl-Mstn expression in claw and thoracic muscle will be determined. dsRNA will be used to determine the effects of RXR/EcR knockdown on Gl-Mstn expression. As C. maenas is refractory to ESA and MLA, the expression of Cm-Mstn will be determined in muscles from spontaneously molting animals. Supported by NSF (IBN-0618203).