Meeting Abstract
P3.43 Saturday, Jan. 5 Quantitative Expression of Myostatin in Tropical Land Crab, Gecarcinus lateralis: Implications for the Regulation of Muscle Atrophy. BADER, B.D.*; KIM, H.W.; COVI, J.A.; CHANG, E.S.; MYKLES, D.L.; Colorado State University; Pukyong National University; Colorado State University; UC Davis Bodega Marine Lab; Colorado State University bbader@simla.colostate.edu
Molting is the periodic shedding of the exoskeleton required for organismal growth in arthropods. Ecdysteroid hormones initiate cellular processes necessary for successful exuviation. One process is a programmed atrophy of the claw muscle, in which the mass is reduced 2-3-fold. This allows the claws to be pulled through the small joints of the appendage at molt. How ecdysteroids induce claw muscle atrophy is poorly understood. Myostatin (Mstn), a member of the TGFβ family of growth factors, is a negative regulator of muscle growth in mammals and birds. We have cloned cDNAs encoding Mstn in scallop, land crab, and green crab muscles, which suggests that Mstn also controls the size of invertebrate muscles. Our hypothesis is that ecdysteroids increase the expression and activation of Mstn, leading to the expression of genes required for the degradation of myofibrillar proteins. Real-time Reverse Transcription PCR (qRT-PCR) was performed to quantify the relative expression of myostatin in various time points pre- and post-molt. Multiple limb autonomy (MLA) was performed to induce molting and limb bud growth was used to monitor molting stage. Expression data indicates an elevated expression of myostatin in claw muscle tissue during early to middle pre-molt, supporting our hypothesis of myostatin involved in claw muscle atrophy occurring during pre-molt. Furthermore, the data suggests a decrease in myostatin expression in late pre-molt and early post-molt, suggesting down-regulation is needed to rebuild muscle tissue following ecdysis. Supported by NSF (IBN-0618203), an Arnold and Mabel Beckman Foundation Scholarship, and an Undergraduate Research Institute Scholarship to B.D.B.
