[39] Cloning developmentally regulated gene families

Abstract

Over the past few years it has become increasingly clear that the principal means of evolution at the genomic level is through gene duplication and divergence. This has resulted in the realization that many genes once described as "single copy" are actually members of relatively large gene families. The primary method used to search for members of a gene family has been to screen either genomic or cDNA libraries at low stringency with a DNA probe encoding an amino acid motif that is believed to be conserved. This approach has been quite successful when the conserved motif is relatively large, as in the case of the homeotic genes. However, it does have a number of disadvantages. In particular, one is relying on conservation of the DNA sequence used as a probe when in the majority of cases it is the encoded amino acid sequence that is being evolutionarily conserved. As a result, when the conserved motif within a gene family is relatively small, the degeneracy of the triplet code can make detection of other family members virtually impossible using this method

Additional details