title: Isolation, characterization and comparison of Atlantic and Chinook salmon growth hormone 1 and 2.
abstract: BACKGROUND
  Growth hormone (GH) is an important regulator of skeletal growth, as well as other adapted processes in salmonids. The GH gene (gh) in salmonids is represented by duplicated, non-allelic isoforms designated as gh1 and gh2. We have isolated and characterized gh-containing bacterial artificial chromosomes (BACs) of both Atlantic and Chinook salmon (Salmo salar and Oncorhynchus tshawytscha) in order to further elucidate our understanding of the conservation and regulation of these loci.
  
  
  RESULTS
  BACs containing gh1 and gh2 from both Atlantic and Chinook salmon were assembled, annotated, and compared to each other in their coding, intronic, regulatory, and flanking regions. These BACs also contain the genes for skeletal muscle sodium channel oriented in the same direction. The sequences of the genes for interferon alpha-1, myosin alkali light chain and microtubule associated protein Tau were also identified, and found in opposite orientations relative to gh1 and gh2. Viability of each of these genes was examined by PCR. We show that transposon insertions have occurred differently in the promoters of gh, within and between each species. Other differences within the promoters and intronic and 3'-flanking regions of the four gh genes provide evidence that they have distinct regulatory modes and possibly act to function differently and/or during different times of salmonid development.
  
  
  CONCLUSIONS
  A core proximal promoter for transcription of both gh1 and gh2 is conserved between the two species of salmon. Nevertheless, transposon integration and regulatory element differences do exist between the promoters of gh1 and gh2. Additionally, organization of transposon families into the BACs containing gh1 and for the BACs containing gh2, are very similar within orthologous regions, but much less clear conservation is apparent in comparisons between the gh1- and gh2-containing paralogous BACs for the two fish species. This is consistent with the hypothesis that a burst of transposition activity occurred during the speciation events which led to Atlantic and Pacific salmon. The Chinook and other Oncorhynchus GH1s are strikingly different in comparison to the other GHs and this change is not apparent in the surrounding non-coding sequences.
authors.affiliation: Centre for Biomedical Research, University of Victoria, Victoria, British Columbia, V8W 3N5, Canada. krvs@uvic.ca
authors.forename: Kristian R
authors.initials: KR
authors.lastname: von Schalburg
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yazawa
authors.forename: Johan
authors.initials: J
authors.lastname: de Boer
authors.forename: Krzysztof P
authors.initials: KP
authors.lastname: Lubieniecki
authors.forename: Benjamin
authors.initials: B
authors.lastname: Goh
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Straub
authors.forename: Marianne R
authors.initials: MR
authors.lastname: Beetz-Sargent
authors.forename: Adrienne
authors.initials: A
authors.lastname: Robb
authors.forename: William S
authors.initials: WS
authors.lastname: Davidson
authors.forename: Robert H
authors.initials: RH
authors.lastname: Devlin
authors.forename: Ben F
authors.initials: BF
authors.lastname: Koop
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D022202:Chromosomes, Artificial, Bacterial; D020451:Contig Mapping; D004251:DNA Transposable Elements; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D015723:Gene Library; D013006:Growth Hormone / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012474:Salmon / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements; D018076:DNA, Complementary; D013006:Growth Hormone