Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2005
Publication Date: 3/19/2005
Citation: Gahr, S.A., Rexroad III, C.E. 2005. Gene expression of the inhibitor of DNA binding (ID) proteins during embryonic development in the rainbow trout (oncorhynchus mykiss). Aquaculture America Conference January 17-20, page 140 New Orleans, LA.
Technical Abstract: The ID (Inhibitor of DNA Binding/Differentiation) proteins represent a family of dominant negative regulators of the basic helix-loop-helix (bHLH) transcription factors whose activities result in delayed cell differentiation and prolonged proliferation. In the current study, we have isolated the mRNA and genomic sequence for six ID proteins (four previously unidentified) and developed real-time PCR assays to determine tissue distribution and embryonic expression pattern in the rainbow trout. Putative ID genes were identified in the Rainbow Trout Gene Index (http://www.tigr.org/tdb/tgi/rtgi/) and subsequently in the NCCCWA rainbow trout BAC library. A total of six unique ID genes have been identified in the rainbow trout. Based on homology to previously identified ID genes, we have classified four of the six as ID1s (ID1A, ID1B, ID1C and ID1D) and the remaining two as ID2s (ID2A and ID2B). Sequence homology and gene structure indicate that the family members arose from a combination of gene and genome duplication. As shown in Table 1, all six proteins share substantial similarity within the HLH domain, and diverge in other regions of the protein. Results of the real-time PCR assays show the ID proteins are expressed in a variety of adult rainbow trout tissues. The ID gene expression pattern was determined for Day 0 (Unfertilized Eggs), 2, 9, 18, 30 and 50 of embryonic development. As reported in other species, the highest expression was found during proliferative stages of development and reduced during periods of cellular differentiation. In summary, we have identified members of the ID protein family in the rainbow trout and have begun to elucidate their importance for rainbow trout growth and development. Better understanding of ID protein functions could lead to more precise interventions for improved growth in rainbow trout.