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Vaccinia virus cores contain a type I topoisomerase which promotes the relaxation of superhelical DNA of either handedness (Bauer et al., Proc. Natl. Acad. Sci. U.S.A. 74:1841-1845, 1977). The activity of partially purified vaccinia virus topoisomerase (VV-Topo I) was determined in the presence of ATP, dATP, GTP, ADP, and ATP analogs in which hydrolysis of(More)
Purified human DNA topoisomerase I was assayed quantitatively by enzyme titrations with supercoiled pHC624 DNA in the presence of 0–2.0 μm doxorubicin. Supercoiled and relaxed DNAs were resolved by agarose gel electrophoresis in the presence of ethidium bromide, and the pereentage of conversion of supercoiled DNA to relaxed DNA was quantified by scanning(More)
A preliminary map of the frog virus 3 (FV 3) genome was constructed by hybridization-selection of mRNAs to cloned DNA fragments and translation in reticulocyte lysates. FV 3 mRNAs were hybridized toKpnI,HindIII, andSalI restriction fragments representing the entire FV 3 genome. Two different hybridization conditions were employed in order to discriminate(More)
Earlier studies have suggested that higher cellular levels of teniposide (VM-26) are required for the inhibition of growth in L1210/VM-26 sublines than in parental L1210 cells [8]. On the basis of this observation, we hypothesized that resistance to VM-26, which is partly attributed to multidrug resistance, also resulted in reduced formation of DNA lesions(More)
DNA topoisomerase activity can be rapidly assayed by measuring the change in ethidium bromide fluorescence intensity after treatment of closed duplex DNA with enzyme. The sensitivity of the fluorometric assay has been enhanced 3-fold by a 10-fold reduction in ethidium bromide concentration to 0.1 microgram/ml. The results of the fluorometric assays are in(More)
Multiple DNA-dependent enzyme activities have been detected in highly purified preparations of a single-strand-specific nuclease from vaccinia virus. These enzyme preparations were extensively purified and characterized by using superhelical DNAs as substrates. In particular, the nuclease activity was monitored by the extent of conversion of supercoiled(More)
We isolated a new larval color mutant, brown larva (b), from the Bangalore, India strain of Anopheles stephensi Liston. The gene b is an autosomal recessive with uniform expression and complete penetrance. We conducted extensive crosses to establish allelism between brown larva (b) and green larva (g) reported previously in An. stephensi from our(More)
Faithful transcription of a vaccinia virus gene was accomplished in vitro by using a soluble extract prepared from vaccinia virus-infected HeLa cells. Specific transcription of the cloned vaccinia virus gene was detected by using template DNA restricted within the transcribed region. The vaccinia virus gene was not transcribed by extracts prepared from(More)
The induction by interleukin-2 of DNA topoisomerase I and DNA topoisomerase II activities in the human T cell line HuT 78 was investigated. HuT 78 cells were treated with 1000 U of interleukin-2/ml, and extracts of the HuT 78 nuclei were prepared over a 24h period. The extracts were assayed quantitatively for the activities of DNA topoisomerase I and DNA(More)
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