title: The two myostatin genes of Atlantic salmon (Salmo salar) are expressed in a variety of tissues.
abstract: Two myostatin isoforms were identified in Atlantic salmon (Salmo salar) by RT-PCR, and genomic sequences encoding this negative muscle growth factor were for the first time isolated from a nonmammalian species. Salmon myostatin isoform I is transcribed in white skeletal muscle as a 2346-nucleotide mRNA species that encodes a precursor protein of 373 amino acids. Salmon myostatin I shows 93% sequence identity with isoform II which was isolated from white muscle as a partial cDNA sequence of 1409 nucleotides. In contrast to the restricted gene expression of myostatin in mammals, salmon myostatin I and II mRNAs were identified by RT-PCR in multiple tissues, including white muscle, intestine, brain, gills, tongue and eye. In addition, isoform I mRNA was found in red skeletal muscle, heart, spleen, and ovarian tissue. Using polyclonal antibodies against both isoforms, a 55-kDa precursor protein was detected by Western blot analysis in the red and white skeletal muscle, heart, intestine, and brain. Immunoreactive peptides of 35-40 kDa were identified in the gills, tongue, spleen, and head kidney, while the 25-kDa mature myostatin was found in the eye and serum, and in vitro expressed in rabbit reticulocyte lysate. Salmon myostatin was immunohistochemically localized in the sarcoplasma of red and white muscle fibres, in intestinal epithelial cells, at the basis of the branchial primary lamellae, and in odontoblasts and ameloblasts of the tongue teeth. The results indicate that the role of fish myostatin may not be restricted to muscle growth regulation, but may have additional functions similar to the growth/differentiation factor-11 in mammals.
authors.affiliation: Institute of Aquaculture Research, Aas, Norway.
authors.forename: T K
authors.initials: TK
authors.lastname: Østbye
authors.forename: T F
authors.initials: TF
authors.lastname: Galloway
authors.forename: C
authors.initials: C
authors.lastname: Nielsen
authors.forename: I
authors.initials: I
authors.lastname: Gabestad
authors.forename: T
authors.initials: T
authors.lastname: Bardal
authors.lastname: Andersen Ø
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D029941:Fish Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D055435:Myostatin; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020317:Salmo salar / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000737:chemistry / Q000235:genetics* / Q000276:immunology
chemical_list: D029941:Fish Proteins; D007106:Immune Sera; C525911:MSTN protein, human; D055435:Myostatin; D020033:Protein Isoforms; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta