Analysis of 5′-Termini of Early Intermediates of Okazaki Fragments Accumulated in Thymocytes after Emetine Treatment of Mice

Abstract

Nascent Hg-DNA synthesized by the incorporation of Hg-dCTP in reversibly permeable cells of murine thymocytes has been characterized earlier. Here we describe the analysis of 5′ ends of oligonucleotides isolated from thymocytes 48 hr after a single dose of emetine administration to mice. This small-molecular-weight population of nascent DNA shorter than Okazaki fragments was absent in control cells. More than 90% of the terminally ³²P-labeled oligonucleotides carried a terminally phosphorylated RNA moiety at the 5′ end, as demonstrated by alkaline hydrolysis. The size of the short nascent DNA fragments carrying RNA primers ranged between 9 and 50 nucleotides with an average chain length of 15 nucleotides. These oligomers are regarded as the precursors of the Okazaki fragments.