[Certain properties of transcribed fragments of the mouse genome cloned in plasmid pBR322].

Clones of total mouse DNA efficiently hybridized with mRNA (or cDNA) were selected by colony hybridization technique. The majority of selected fragments demonstrate hybridization with cDNA, dsRNA-B (isolated from pre-mRNA) and oligo(dT). The data obtained indicate that the base sequences hybridizing to these test-probes are contiguous within several individual cloned restriction DNA fragments. At least in two cases sequences hybridizing with cDNA belong to repetitive fraction of the mouse genome (presumptive repetitive structural genes). They are transcribed effectively, and respective mRNAs of abundant type. Two other clones contain structural genes which are expressed into mRNAs of non-abundant type.