cDNA Cloning and Analyses of Two Myosin Heavy Chain Isoforms of Mandarin Fish (Siniperca chuatsi) Based on Transcriptome Sequencing

Abstract:

Myosin heavy chain (MYH) is the main component of the skeletal muscle thick filament. The expression levels of MYHs have significant influences on the formation of thick filaments and muscle development. To understand the roles of MYHs on growth during the early development of mandarin fish (Siniperca chuatsi), the differentially expressed unigenes from the transcriptome sequencing data of the fast and slow growing fish were analyzed, and two highly expressed unigenes of MYH were screened. The full length cDNAs of these two MYH-7s, MYH-7a and MYH-7b were obtained by RACE method; they were 6070 bp and 5896 bp in length, with coding regions of 5820 bp and 5745 bp, respectively. Sequencing analysis showed that both MYH-7s contain the conserved regions such as Loop1 and Loop2, and ATP binding sites. The evolutionary tree clustering analysis showed that both MYH-7s genes belong to the slow muscle type MYH. The expression patterns of the two MYH-7s in different tissues were detected by qRT-PCR. The highest expression of MYH-7a was found in heart muscle while MYH-7b was highly expressed in red muscle. The expression levels of both MYH-7a and MYH-7b increased gradually in accordance with the embryonic development stages. The expression levels of the MYH-7s in the fast growing group were significantly higher than in the slow growing groups in 15, 30-day post hatching (dph), while both genes showed lower expression levels in fast growing group than in slow growing group in 60 dph. The different expression levels in tissues and early developmental stages of these two genes in the fast and slow growing groups suggested that they play important roles in the embryonic and early development of S. chuatsi.