Centro Nacional de Biotecnología, Campus Univ. Autónoma, 28049 Madrid, Spain, Health Research Inc., Howard Hughes Medical Institute at Wadsworth Center, Empire State Plaza, Albany, NY 12201-0509, and Department of Biomedical Sciences, State University of New York at Albany, University of Konstanz, Department of Biology, 78457 Konstanz, Germany, Max-Planck-Institut fur Biophysik, Frankfurt, Germany

This paper describes the purification of polysomal RNA from SV40-lytically infected CV1 (monkey) cells and separation of the two distinct classes of SV40-specific mRNA sedimenting at 16 S and 19 S. These classes have been hybridized with the whole SV40 DNA genome as well as with the SV40 Hind fragments. The results have permitted the mapping of SV40-specific late 16 S mRNA from approximately 0....