Myosin heavy chains and twelve actins differentially expressed in muscle fiber types from American Lobster (Homarus americanus)

Abstract

Unlike mammals, crustacean muscle fibers dynamically change according to the developmental and molting stage. It is important to understand molecular mechanism of its plasticity and there are many possible applications for medical and aquaculture industry. In present study, twelve actins and one myosin heavy chain (MHC) cDNAs were isolated from the different tissues of American lobster, Homarus americanus; eight skeletal muscle type actins (HA-ActinSK), one cardiac muscle type actin (HA-ActinHT), three cytoplasmic type actins (HA-ActinCT) and fast type MHC. End-point RT-PCR and quantitative PCR results showed that HA-ActinSK1 and SK2 are major actins of the crusher claw muscle and HA-ActinSK3, SK4 and SK5 are main actins of cutter claw muscle. Deep abdominal (DA) muscles were mainly composed of HA-ActinSK5 and SK8 and DA flexor contains additional HA-ActinSK7. HA-ActinSK7 may be important component to distinguish between DA flexor and extensor muscle. HA-ActinHT1 is exclusively expressed in the heart muscle. Three cytoplasmic actins, HA-ActinCT1, CT2 and CT3 were predominantly expressed in the hepatopancreas. Isolated MHC was strongly expressed in the fast type muscles (cutter, DAF, DAE). Amino acid sequence alignment and phylogenetic analysis results suggest that actins and MHCs appear to be functionally active and exhibit each muscle fiber type charaters. In addition, each gene was highly related to the tissue where they expressed, suggesting that amino acid sequence of each is strongly related with functional or structural character of each tissue type.