Meeting Abstract

98.2  Thursday, Jan. 7  Prolonged Cold Exposure in Young Quail: avUCP, Ultrastructure and Catabolic Capacities in Skeletal Muscle OLSON, JM*; CARAGIULO, A; CZERWINSKI SHIELDS, BV; SOUCIER, D; Villanova University; Fordham University; Villanova University; Villanova University john.olson@villanova.edu

Skeletal muscle is the site of both shivering thermogenesis (ST) and regulatory nonshivering thermogenesis (NST) through avian uncoupling protein (avUCP). Thermogenic capabilities may be upregulated in response to chronically cold ambient temperatures, especially during development. Japanese Quail were acclimated to cold (5°C) or warm temperatures (25°C) for three weeks starting at age 14d posthatch (CA and WA, resp.). Pectoralis muscle of CA birds possessed more avUCP, but, contrary to predictions, mitochondrial area (as % total fiber area) was not elevated in the CA birds, even though mitochondrial area did increase significantly with age in both groups. Interestingly, however, muscle mitochondria of CA birds possessed more cristae, suggesting the possibility that these birds could have concomitantly higher catabolic capacities to support both elevated ST and NST. Activities of three regulatory enzymes (pyruvate kinase, citrate synthase, and 3-hydroxyacyl-CoA-dehydrogenase) were assayed at three temperatures in pectoralis and gastrocnemius muscles from CA and WA birds. As predicted, enzyme activities increased with temperature, but catabolic capacities did not increase with CA in either muscle. Additionally, thermal sensitivities of catabolic enzymes did not differ in CA birds. This lack of significant differences, together with depressed growth and lower body temperature in CA birds, suggest birds acclimated in part through regulated hypothermia