Submitted to: Plant and Animal Genome
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2005
Publication Date: 1/15/2005
Citation: Gahr, S.A., Rexroad III, C.E. 2005. Tissue distribution and embryonic expression of the inhibitor of differentiation/DNA binding (ID) family of proteins in the rainbow trout (Oncorhynchus mykiss). Plant and Animal Genome, XIII P603, pg 221.
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. We have previously identified the rainbow trout mRNA and genomic sequences for six ID proteins (four previously unidentified) and developed real-time PCR assays for functional genome analyses including determination of tissue distribution and embryonic expression patterns. These proteins have been classified based on homologies to previously identified ID genes including four ID1s (ID1A, ID1B, ID1C and ID1D) and two ID2s (ID2A and ID2B). Each class of ID gene shares a similar genomic sequence and shows the protein features specific to that class. Tissue distribution of the ID proteins shows redundancy in expression between the most closely related family members. That is, we found significant overlap in the expression of ID1A and ID1D (91% similarity) with IDB (77% similarity) showing somewhat different tissue distribution. However, there were instances where the two closest proteins show substantial differences in expression. For example, ID2A was found to have much higher expression than ID2B in the pyloric ceca and the intestines. Gene expression patterns were determined for Day 0 (Unfertilized Eggs), 2 (blastula), 9 (gastrula), 18 (eyed), 30 (hatch) and 50 (1st feeding) of embryonic development. Expression was observed to be low in unfertilized eggs and increased throughout embryonic development. As reported in other species, higher expression levels were observed during proliferative stages of development and reduced during periods of cellular differentiation.