Selection of rat genomic clones transcribed into brain polysomal RNA

A library of rat DNA in the lambda phage vector Charon 4A was screened with a cDNA probe transcribed from a brain polysomal poly(A)+RNA template. Clones were selected that served as templates for transcripts which were more abundant in brain than in liver. It was essential to add a large excess of repetitive DNA to the hybridization mixtures to prevent the cDNA from annealing to ubiquitous repetitive rat DNA in the clones. The abundance of the brain and liver polysomal poly(A)+ transcripts of one clone was determined.