title: Cloning and characterization of a highly reiterated 5.8-kilobase pair nucleolar EcoRI DNA fragment found in Novikoff hepatoma ascites cells.
abstract: The DNA of Novikoff hepatoma ascites cells was found to contain a 3.6-megadalton EcoRI restriction fragment, referred to as EcoRI fragment A (Parker et al., 1979). C0t analyses demonstrated an enrichment of fragment A sequences in Novikoff hepatoma genome relative to normal rat liver DNA. This fragment was cloned in lambda gtWES to determine its molecular structure and sequence organization. The DNA from a positive clone was labeled by nick translation and hybridized to a Southern blot of EcoRI digested Novikoff DNA. Distinct hybrids formed with the region corresponding to fragment A. The greater degree of hybridization to the nucleolar fraction suggested a nucleolar enrichment of fragment A. Fragment A has a PstI site approximately 300 base pairs from one terminus which was used to generate mono-5'-32P-labeled fragments. The larger PStI subfragment, 5500 base pairs, labeled at a single terminus, was used to evolve a restriction enzyme map. The 300 base pair fragment was partially sequenced, revealing the presence of a repetitive sequence "island", TT(GTCT)8(GAAT)5G-. C0t analysis, utilizing the purified clone as a probe, confirmed the enrichment of fragment A sequences in the tumor relative to the normal rat liver control.
mesh_terms: D000818:Animals; D001482:Base Composition; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis*; D004262:DNA Restriction Enzymes; D008114:Liver Neoplasms, Experimental / Q000032:analysis*; D009693:Nucleic Acid Hybridization; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004247:DNA; D004262:DNA Restriction Enzymes