SZUCSIK, A. M.*; ROURKE, B.C.; BENNETT, A.F.; HICKS, J.W.; University of California-Irvine; University of California-Irvine; University of California-Irvine; University of California-Irvine: Effects of aerobic exercise training on myosin heavy chain isoform expression in the Savannah Monitor Lizard Varanus exanthematicus

Prior investigations indicate that reptiles do not demonstrate phenotypic plasticity in the oxygen transport system in response to aerobic exercise training at the organismal level. Whether phenotypic plasticity exists at the molecular level in response to a training stimulus is unknown. We tested the hypothesis that skeletal muscle extracted from sedentary and exercise-trained V. exanthematicus would differ with respect to myosin heavy chain (MHC) isoform gene and protein expression. Six hindlimb muscles (puboischiotibialis, iliofibularis, iliotibialis, ambiens, flexor tibialis internus, and gastrocnemius) were extracted from sedentary (n = 6) and exercise-trained (n = 8) lizards and compared with regards to MHC isoform gene and protein expression. We cloned partial sequences of MHC isoforms via 3� RACE and assessed levels of MHC isoform gene expression using semi-quantitative RT-PCR. We monitored MHC isoform protein expression via single-fiber/whole muscle homogenate SDS-PAGE analysis. Preliminary evidence indicates MHC isoform expression patterns suggestive of skeletal muscle plasticity and thus presence an exercise training response in V. exanthematicus at the molecular level. Supported by NSF Grant IBN 0091398 (AFB/JWH) and NIH Postdoctoral Fellowship AR47749-01 (BCR).