R-loop hybridization of collagen DNA: separation in Cs2SO4 gradients

High molecular weight poly(A)RNA (26-35 S) from chicken embryo trunks which is enriched for collagen mRNA was iodinated and hybridized to DNA under conditions of R-loop formation. The R-loops were separated in Cs2SO4 gradients from the bulk of DNA yielding double stranded DNA enriched for collagen genes.