expression of parvalbumin isoforms will differ between the anterior and posterior red muscle, but little longitudinal variation will be observed in parvalbumin expression in white and pink muscle. We successfully employed protein electrophoresis (SDS-PAGE) with western blots to identify two parvalbumin isoforms in each muscle fiber type. SDS-PAGE and densitometry were used to determine the relative expression levels of the two parvalbumin isoforms and total parvalbumin expression. Red muscle displays a significant shift, from anterior to posterior, in the relative expression of the two isoforms, both in their relative contribution and in total parvalbumin content, but white and pink muscle did not. The red muscle of southern kingfish, Menticirrhus americanus (Pisces, F. Scianidae) showed a pattern similar to the red muscle of sheepshead.

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