Bovine fast-twitch myosin light chain 1: cloning and mRNA amount in muscle of cattle treated with clenbuterol
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The cDNA clone encoding the fast-twitch isoform of myosin light chain 1 (MLC-1f) was isolated from bovine longissimus dorsi muscle and sequenced in M13 and pUC8. An 0.8-kb subclone, produced by digestion of the cDNA with EcoRI, contained the portion of the molecule common to MLC-1f and MLC-3f. The cDNA in pUC8 contained an additional 81 bp upstream of the EcoR I digestion site, which was unique to MLC-1f. The cDNA clone was used to measure MLC-1f mRNA in longissimus dorsi muscle of cattle chronically administered the beta-adrenergic agonist clenbuterol. Treatment with clenbuterol for 50 days increased succinic dehydrogenase negative (type IIB) and positive (types I and IIA) myofiber cross-sectional areas by 25%. After the 50-day treatment period, the amount of MLC-1f mRNA was 90% greater in longissimus dorsi muscle of treated animals than in the initial group. This effect was lost when clenbuterol treatment was withdrawn for a 78-day period, during which time muscle growth in the treated animals stopped completely. We conclude that we have cloned the bovine cDNA for MLC-1f, which has provided additional evidence that beta-adrenergic agonists increase myofibrillar gene expression.
author list (cited authors)
Smith, S. B., Davis, S. K., Wilson, J. J., Stone, R. T., Wu, F. Y., Garcia, D. K., Lunt, D. K., & Schiavetta, A. M.