Pou domain proteins are transcription factors that have been found to be important in neuronal cell identity in C. elegans, immunoglobulin production in B cells in humans, and neuron-specific expression of the dopa decarboxylase gene in Drosophila. There are a growing number of pou genes found in many species which play important roles in development, especially of the nervous system. The innervation of the heart and the mesoderm of the great vessels are derived from neural crest tissue in the embryo. Since these cardiac tissues are neuronally derived, pou genes could be important in heart development as well. Chicken heart and embryonic cDNA and chicken genomic libraries were screened using degenerate PCR primers derived from the most conserved areas of the pou domain amino acid sequence. This sequence varies little across species or class of pou proteins. We have also used reverse transcriptase and the same primers to screen chicken brain mRNA for the chicken homolog of the pou gene. The PCR reactions yielded 350 bp fragments as predicted by the Drosophila pou (Dph.1) sequence. These fragments were subcloned into pBluescript SK+ (Stratagene). We are now sequencing the fragments. If any unique pou genes are identified, we will explore the timing and distribution of their expression in chick embryos by in situ hybridization and rescreening of specific chicken cDNA libraries.
