ISOFORM DISTRIBUTION OF PARVALBUMINS AND OF SOME MYOFIBRILLAR PROTEINS IN ADULT AND DEVELOPING CHRYSICHTHYS-AURATUS (GEOFFROY-ST-HILAIRE, 1808) (PISCES, CLAROTEIDAE)

Polyacrylamide gel electrophoresis was used to analyse the distributio n of parvalbumin, myosin light chain, and troponin I isoforms in white muscles of larval, juvenile, and adult Chrysichthys auratus (catfish, siluriforms) and to study the kinetics of their synthesis. Parvalbumi n isoform PA II was first detected from day 5 post-hatching and was th e main ''larval'' isoform in this species. PA III appeared at the begi nning of the juvenile stage bur always remained the minor isoform, eve n in adult fish. Young mature specimens (approximately 12 cm long) dis played the highest total parvalbumin content Adult-type myosin light c hains were detected from day 8. Densitometric analysis confirmed the l ight-chain distribution typical of fish muscles, with a relatively hig h amount of LC3 and a low amount of LC1. We evidenced a ''larval'' for m of troponin-1 and its progressive replacement by art ''adult'' form.