MYOFIBRILLAR PROTEINS IN DEVELOPING WHITE MUSCLE OF THE ARCTIC CHARR, SALVELINUS-ALPINUS (L)

Myosin light chains from Arctic charr muscles have previously been identified by SDS-polyacrylamide gel electrophoresis of electrophoretically purified native myosin. Tropomyosins were identified by two-dimensional electrophoretic comigration with rat muscle proteins in the absence and presence of urea. Three tropomyosin spots were detected in embryos. The isoform of lower electrophoretic mobility and lower pI became predominant in white muscle while the other two isoforms, differing only slightly in electrophoretic mobility and pI, became predominant in red muscles. In cardiac tissue, a fourth tropomyosin spot was found of slightly lower pI and higher electrophoretic mobility than the two spots from the red muscle. White muscle tropomyosin had lower electrophoretic mobility than rat muscle beta-tropomyosin. The two tropomyosins from charr red muscle and the tropomyosin from cardiac muscles were clustered close to the rat alpha-tropomyosin. Neither cardiac nor red myosin light chains were detected in the developing musculature. White muscle myosin from all the Arctic charr analysed from two locations in Norway, Hammerfest and Takvatn, possessed two myosin light chains type 1, but three out of four charrs from a third location, Sila, possessed three myosin light chains type 1.