Fibre type-specific expression patterns of myosin heavy chain genes in adult torafugu Takifugu rubripes muscles

Abstract

SUMMARYComprehensive in silico studies, based on the total fugu genome database, which was the first to appear in fish, revealed that torafugu Takifugu rubripes contains 20 sarcomeric myosin heavy chain (MYH) genes (MYH genes) (Ikeda et al., 2007). The present study was undertaken to identify MYH genes that would be expressed in adult muscles. In total, seven MYH genes were found by screening cDNA clone libraries constructed from fast, slow and cardiac muscles. Three MYH genes, fast-type MYH M86-1 , slow-type MYH M8248 and slow/cardiac-type MYH M880 , were cloned exclusively from fast, slow and cardiac muscles, respectively. Northern blot hybridization substantiated their specific expression, with the exception of MYH M880 . In contrast, transcripts of fast-type MYH M2528-1 and MYH M1034 were found in both fast and slow muscles as revealed by cDNA clone library and northern blot techniques. This result was supported by in situ hybridization analysis using specific RNA probes, where transcripts of fast-type MYH M2528-1 were expressed in fast fibres with small diameters as well as in fibres of superficial slow muscle with large diameters adjacent to fast muscle. Transcripts of fast-type MYH M86-1 were expressed in all fast fibres with different diameters, whereas transcripts of slow-type MYH M8248 were restricted to fibres with small diameters located in a superficial part of slow muscle. Interestingly, histochemical analyses showed that fast fibres with small diameters and slow fibres with large diameters both contained acid-stable myofibrillar ATPase, suggesting that these fibres have similar functions, possibly in the generation of muscle fibres irrespective of their fibre types. Supplementary material available online at

Species-specific expression variation of fish MYH14, an ancient vertebrate myosin heavy chain gene orthologue

“…Our genomic analysis showed obvious synteny between the regions of human MYH14 and fish orthologues. In addition, these fish MYH14 orthologues were found to be actually expressed in torafugu in our previous study [9,13] and in zebrafish in the present study. While MYH14 in mammals is expressed mainly in slow and cardiac muscles [5,8], its mRNA levels were found to be quite low in comparison with those of other sarcomeric MYHs [8].…”

“…Interestingly, MYH14 was also expressed in intermediate muscle fibers of the adult zebrafish. Akolkar et al [13] found no expression of MYH M5 in the fast muscle of adult torafugu.…”

“…While MYH14 in mammals is expressed mainly in slow and cardiac muscles [5,8], its mRNA levels were found to be quite low in comparison with those of other sarcomeric MYHs [8]. Akolkar et al [13] revealed that MYH M5 , a torafugu MYH14 orthologue, is one of the NDRG family member 3, TRCP4AP transient receptor potential cation channel subfamily C member 4 associated protein, Snail1 snail homologue 1, CYLD cylindromatosis, TOP1 topoisomerase I major components in the MYH repertoire expressed in torafugu slow and cardiac muscles. The present study also showed a high expression of MYH14 in zebrafish embryos and adults, suggesting its pivotal role in fish muscle formation.…”

“…Ikeda et al [9] showed that MYH M5 , a torafugu Takifugu rubripes MYH14 orthologue, is expressed specifically in slow and cardiac muscles at the same developmental stage as its mammalian counterpart. Detailed expression analysis revealed that MYH M5 is one of the major components in the MYH repertoire expressed in slow and cardiac muscles of adult torafugu [13], suggesting its pivotal role in fish muscle formation.…”

Characterization of Pax3 and Pax7 genes and their expression patterns during different development and growth stages of Japanese pufferfish Takifugu rubripes

“…In an adult torafugu (275 g body weight), fast and slow muscle in the trunk were identified and obtained as described previously (Akolkar et al, 2010) and used for cDNA cloning.…”