title: Evaluation of potential reference genes in real-time RT-PCR studies of Atlantic salmon.
abstract: BACKGROUND
  Salmonid fishes are among the most widely studied model fish species but reports on systematic evaluation of reference genes in qRT-PCR studies is lacking.
  
  
  RESULTS
  The stability of six potential reference genes was examined in eight tissues of Atlantic salmon (Salmo salar), to determine the most suitable genes to be used in quantitative real-time RT-PCR analyses. The relative transcription levels of genes encoding 18S rRNA, S20 ribosomal protein, beta-actin, glyceraldehyde-3P-dehydrogenase (GAPDH), and two paralog genes encoding elongation factor 1A (EF1AA and EF1AB) were quantified in gills, liver, head kidney, spleen, thymus, brain, muscle, and posterior intestine in six untreated adult fish, in addition to a group of individuals that went through smoltification. Based on calculations performed with the geNorm VBA applet, which determines the most stable genes from a set of tested genes in a given cDNA sample, the ranking of the examined genes in adult Atlantic salmon was EF1AB>EF1AA>beta-actin>18S rRNA>S20>GAPDH. When the same calculations were done on a total of 24 individuals from four stages in the smoltification process (presmolt, smolt, smoltified seawater and desmoltified freshwater), the gene ranking was EF1AB>EF1AA>S20>beta-actin>18S rRNA>GAPDH.
  
  
  CONCLUSIONS
  Overall, this work suggests that the EF1AA and EF1AB genes can be useful as reference genes in qRT-PCR examination of gene expression in the Atlantic salmon.
authors.affiliation: National Institute of Nutrition and Seafood Research, Nordnesboder 2, N-5005 Bergen, Norway. pal.olsvik@nifes.no
authors.forename: Pål A
authors.initials: PA
authors.lastname: Olsvik
authors.forename: Kai K
authors.initials: KK
authors.lastname: Lie
authors.forename: Ann-Elise O
authors.initials: AE
authors.lastname: Jordal
authors.forename: Tom O
authors.initials: TO
authors.lastname: Nilsen
authors.forename: Ivar
authors.initials: I
authors.lastname: Hordvik
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D005511:Food Handling; D005796:Genes; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012015:Reference Standards; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards*; D012269:Ribosomal Proteins / Q000235:genetics; D020317:Salmo salar / Q000235:genetics*; D014018:Tissue Distribution
chemical_list: D000199:Actins; D020648:Peptide Elongation Factor 1; D012337:RNA, Ribosomal, 18S; D012269:Ribosomal Proteins; C029611:ribosomal protein S20; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases