CDNA CLONING OF MYOSIN HEAVY-CHAIN ISOFORMS FROM CARP FAST SKELETAL-MUSCLE AND THEIR GENE-EXPRESSION ASSOCIATED WITH TEMPERATURE-ACCLIMATION

We have isolated cDNA clones encoding fast skeletal muscle myosin heav y chains of carp acclimated to 10, 20 and 30 degrees C for over 5 week s. All clones covered at least the full length of L-meromyosin, the C- terminal part of the myosin molecule, Nucleotide sequence analysis on cDNA clones showed three types of 3' untranslated sequences, demonstra ting that carp expresses at least three myosin heavy chain isoforms in fast skeletal muscle in an acclimation-temperature-dependent manner. cDNAs were identified which were the predominant types expressed in 10 degrees C- and 30 degrees C-acclimated fish, as well as an intermedia te type present at all acclimation temperatures, Northern blot analysi s using probes of three kinds of DNA fragments from the 3' untranslate d region of carp acclimated to 10, 20 and 30 degrees C further confirm ed the presence of acclimation-temperature-specific isoforms. In addit ion, it was found that mRNA levels of three isoforms were altered in a n acclimation-temperature-dependent manner. When the deduced amino aci d sequences of three types of carp L-meromyosin were compared with tho se of homoiotherms, the 30 degrees C-acclimated type was more similar to those of homoiotherms than was the 10 degrees C-acclimated type.