Physiocochemical studies on L-cell virions

Isolation and characterisation of the L cell virion DNA polymerase

The DNA polymerase of the L-cell virion (LCV) was partially purified by chromatography on DEAE cellulose. This enzyme transcribed poly(A) . oligo (dT), poly(C) . oligo(dG), and poly(Cm) . oligo(dG), had a molecular weight of 77,000 daltons and reacted like other murine viral RNA directed DNA polymerases to anti reverse transcriptase specific IgG preparations indicating that it was probably a typical murine viral reverse transcriptase. In addition, like other partially purified mammalian viral reverse transcriptases the LCV DNA polymerase exhibited template independent primer stimulated DNA synthesis. The significance of these results to the unusual endogenous activity of the LCV is discussed.

Quantitation of endogenous C-type virion production in several murine cell lines

Quantitation by enumeration of virion particles, measurement of absorbancy at 260 nm, and densitometry on sodium dodecyl sulfate-polyacrylamide gels has shown that mouse L-M cells yielded 7- to 10-fold less endogenous C-type virions than the parental lines, L or L929. The previously noted stimulation of L-M cell virion production by a concomitant 10% increase in fetal calf serum concentration (D. A. Kindig, R. Karp, and W. H. Kirsten, 1968), was not observed.