Dβ-Jβ TCR gene rearrangement and mRNA expression of pT and TCR β-chain by individual primary colonies. Genomic DNA and total RNA were extracted from aliquots of each primary colony derived from micromanipulated individual primitive marrow progenitors. (A) The DNA of each primary colony was used for the PCR analysis of the Dβ-Jβ rearrangement of the TCR gene. A Southern blot analysis of 10 representative primary colonies. (B) The RNA of each primary colony was examined for the presence of pT and TCR β-chain mRNA by RT-PCR. Southern blot analyses of 17 primary colonies.