| Myostatin (MSTN), a member of transforming growth factor (TGF)-p superfamily, is a negative regulator of muscle development, it suppresses the development and growth of muscle. To study MSTN of fish is helpful to understand the mechanism of regulation and development of musle of fish; and it is also benenifical for aquaculture to promote the fish production by inhibition of myostatin activity.Gobiocypris rarus and Misgurnus anguillicaudatus were chosen as the subjects to clone myostatin genes, and the expression patterns of the genes were studied. Theβ-actin gene of Gobiocypris rarus was also cloned. The finish of cloning the myostatin andβ-actin will be useful for further studies of regulation and development of muscle in these fishes.The full-length cDNA of myostatin (MSTN) of Gobiocypris rarus was cloned from muscle SMART cDNA library by the method of RACE. MSTN of Gobiocypris rarus is 2184 bp, it has an open reading-frame (ORF) of 1128 bp which encodes a protein of 375 amino acids. Multiple alignment and phylogenetic analyse were conducted with MSTN proteins, the MSTN of Gobiocypris rarus has high identity (54%- 97%) to the MSTNs of other animals. MSTN of Gobiocypris rarus has the typical characters of MSTN, a predomain (position 99 to 255), a mature MSTN domain(position 281 to 375), a conservative hydrolytic site (RIRR, position 263 to 266) and 9 cysteine residues. Sequence analysis predicted that MSTN of Gobiocypris rarus has a putative signal peptide as character of a secretory protein. The temporal and spatial expression pattern of MSTN of Gobiocypris rarus were analyzed by RT-PCR. The rusults showed MSTN mRNA was confined to muscle and eye, the other tested tissues, such as brain, gill, heart, intestine, ovary, liver, testis, had not any detectable expression.Loach (Misgurnus anguillicaudatus ) has been a fishery species recently, so the MSTN of loach was also cloned and charaterized. The partial sequence of MSTN of loach was cloned by RT-PCR with primers based on conservative sequence.The segment of loach MSTN cDNA is 815 base pairs which encodes 271 amino acid residues. The cloned MSTN of loach is nearly the whole sequence of open reading fragment, including a pre-domain, mature MSTN domain, conservative hydrolytic site (RIRR), and 7 conservative cysteine residues. Homology analysis was conducted using amino acid sequences of MSTN of loach, carp, zebrafish, and rainbow trout; the MSTN of loach shares 94%, 92% identities to MSTNs of carp and zebrafish, respectively.The expression pattern of MSTN of loach was checked by RT-PCR, the results shows that the MSTN is expressed strongly in muscle and weakly in eyes, but there were not any detectable expression in other tissues like brain, gill, heart, liver, intestine, testes, and ovary.Based on the expression pattern, it is presumed that MSTN may play some roles in development of eye except of suppression of growth and development of muscle in Gobiocypris rarus and Misgurnus anguillicaudatus.β-actin is a member of the actin family which is an extremely well conserved family of proteins in various species throughout evolution. Like other house-keeping genes, expression ofβ-actin is ubiquitous and constant during all development stages in species, so it is often used as an internal control in many experiment, such as RT-PCR, quantity PCR, Northern blot, etc. However, the sequence ofβ-actin of Gobiocypris rarus has not been reported so far, so the partial sequence ofβ-actin of Gobiocypris rarus was cloned by RT-PCR. The partial sequence ofβ-actin of Gobiocypris rarus is 1029 base pairs which encodes 343 amino acids. The identities of the corresponding partial sequences ofβ-actin between Gobiocypris rarus and other fishes were very high. The results of RT-PCR showed that expression ofβ-actin of Gobiocypris rarus were ubiquital in tissues, like muscle ,eye , brain, heart ,liver , gut , gill, spleen and ovary, and its expression is also continuous and constant during embryonic development.
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