title: Identification and expression profile of the ID gene family in the rainbow trout (Oncorhynchus mykiss).
abstract: ID proteins are negative regulators of basic helix-loop-helix transcription factors governing growth and development in mammals. However, little is known about the ID gene function and expression in fish. We report the identification and characterization of two new rainbow trout ID genes (ID1D and ID2B) and extend our expression analyses of two previously identified ID genes (ID1A and ID2A). Phylogenetic analyses indicate an evolutionary relationship between ID1A and ID1D and between ID1B and ID1C, suggesting a mechanism of divergence throughout salmonid evolution. To access the expression of these genes in adult and developing fish, we measured the relative transcript abundance of four ID1 and two ID2 genes by real-time PCR. ID1 transcripts were expressed in a variety of tissues and the ID1 paralogues showed similar patterns of expression, whereas the ID2 paralogues were differentially expressed. To access the role of the ID genes during embryonic development, gene expression was measured at early (day 0 and day 2), mid (day 9 and day 18) and late (day 30 and day 50) embryonic development. ID1A and ID1D expression remained unchanged throughout embryonic development, while ID1B and ID1C were lowest during early, highest at mid, and decreased during late embryonic development. The ID2 transcripts revealed the highest expression in unfertilized eggs and day 2 embryos, and remained low throughout the remainder of embryonic development. The sequence analyses and gene expression patterns implicate gene and genome duplication in rainbow trout ID gene evolution and suggest an extensive role for the IDs in rainbow trout growth and development.
authors.affiliation: United States Department of Agriculture, Agriculture Research Service, National Center for Cool and Cold Water Aquaculture, 11861 Leetown Road, Kearneysville, WV 25430, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Gahr
authors.forename: M Fernanda
authors.initials: MF
authors.lastname: Rodriguez
authors.forename: Caird E
authors.initials: CE
authors.lastname: Rexroad
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D016678:Genome; D051798:Inhibitor of Differentiation Protein 1; D051797:Inhibitor of Differentiation Protein 2; D017686:Oncorhynchus mykiss / Q000196:embryology* / Q000235:genetics; D009928:Organ Specificity / Q000502:physiology; D010063:Ovum / Q000378:metabolism; D010802:Phylogeny; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D051798:Inhibitor of Differentiation Protein 1; D051797:Inhibitor of Differentiation Protein 2; D012097:Repressor Proteins; D014157:Transcription Factors