Meeting Abstract

P1.118  Sunday, Jan. 4  Cloning of a cDNA encoding a myostatin-like factor from lobster skeletal muscle AXTMAN, L.M.*; CHAO, E.; HJELMFELT, S.H.; STRATTON, M.S.; IMAN, J.D.; COVI, J.A.; MYKLES, D.L.; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins; Colorado State Univ., Fort Collins lisa.axtman@gmail.com

Claw muscles of decapod crustaceans undergo a premolt atrophy, controlled by molting hormones (ecdysteroids), to enable withdrawal of the claws at ecdysis. Myostatin-like factors (Mstn), a negative regulator of muscle growth in mammals, is expressed in scallop, insect, and crustacean muscles, which suggests it also plays a role in controlling muscle size in invertebrates. The American lobster, Homarus americanus, is being used to study the effects of claw size and fiber composition on Mstn-mediated signaling. The larger crusher claw contains only slow-twitch (S1) fibers, while the smaller cutter claw contains fast, S1, and slow-tonic (S2) fibers. We have sequenced a cDNA that encodes Mstn using RT-PCR and RACE-PCR. The conserved RXXR cleavage site was present, indicating the presence of a mature peptide and its N-terminal inhibitory propeptide domain. The nucleotide percent identity for lobster Mstn versus land crab Mstn was approximately 79%, while the amino acid percent identity was approximately 90%. We are quantifying the tissue- and fiber-type-specific expression of Mstn using end-point and quantitative RT-PCR. The results will be related to the control of muscle size by steroid hormones. Supported by NSF (IBN-0618203).