The region of transcriptional initiation in Lytechinus variegatus rRNA genes

Abstract

A sea urchin ribosomal DNA 1.9 kilobase BamHI fragment adjacent to the 5′ end of the 18 S gene has been mapped with the restriction enzymes, XhoI, EcoRI, SmaI and HinfI. A 270 basepair fragment which most likely contains the 5′ end of the presumed primary transcript of rRNA was identified by hybridization of [³²P]DNA fragments to total nuclear RNA separated on methylmercury hydroxide gels and bound to diazobenzyloxymethyl paper. Under these denaturing conditions the size of Lytechinus variegatus precursor rRNA was determined to be 7.2 kilobases (33 S).