B. H. Rosenberg

Learn More
The effects of DNA lesions produced by the carcinogenic alkylating agents ethylnitrosourea and diethylsulfate on the extent of DNA synthesis have been studied in a system utilizing circular single-stranded phiX174 DNA as template and a 392-base restriction fragment as primer with E. coli polymerase I (Klenow fragment). Apurinic sites produced by loss of(More)
Synchronized cells of a normal human lymphocytic cell line contain little swiven enzyme activity in G0 and G1 and high activity in Sphase. The level of activity in different growth phase appears to be related to the fraction of the population engaged in DNA replication. No endogenous inhibitor or activator of swiven activity could be demonstrated. The(More)
DNA swivel (nicking-rejoining) enzyme activity has been studied in various cell fractions of a human lymphoid cell line. Swivel activity is found only in chromatin and in a nuclear membrane fraction containing DNA and possessing endogenous DNA synthesizing activity. Twenty percent of the total swivel activity and less than one percent of the total DNA are(More)
A detailed growth and purification scheme suitable for producing relatively large quantities of fully active, pure SV40 is presented together with data on recovery and purity at each step of the procedure. The scheme was designed to prevent the initial binding of virus to cell components as well as contamination of the extracted virus by cellular DNA.
A highly carcinogenic ethylating agent, ethylnitrosourea (ENU), and a weakly carcinogenic one, diethylsulfate (DES) react with DNA to roughly the same extent but DES produces about 6 times as many unstable ethylated bases, which are gradually lost spontaneously under physiological conditions. The different rates of loss for the different DNA bases have been(More)
DNA has been isolated from synchronized cultures of E. coli 15(T)- at various times. At first the DNA was four-stranded (and indistinguishable in all respects from log phase E. coli DNA), but at the start of DNA synthesis the DNA was found to have halved its molecular weight and to have become two-stranded. This sample had all the properties of undenatured,(More)
The kinetics of degradation of DNA by deoxyribonuclease II have been studied, using the techniques of light scattering, viscosity, and titration. Theoretical equations have been derived for both random and non-random attacks, and all assumptions have been evaluated. It has been shown that these equations permit a valid calculation of the number of(More)
We have studied DNA synthesis in vitro using as template phi X174 DNA containing varying numbers of adducts formed by reaction with cis and trans benzo[a]pyrene (BP) diol-epoxides. The extent of DNA synthesis decreases with increasing numbers of adducts and there is a concomitant decrease in the size of the DNA products. Both decreases can be accounted for(More)