Influence of phage proteins on formation of specific UV DNA photoproducts in phage T7

Phage T7 can be used as a biological UV dosimeter. Its reading is proportional to the inactivation rate expressed in HT7 units. To understand the influence of phage proteins on the formation of DNA UV photoproducts, cyclobutane pyrimidine dimers (CPD) and (6-4)photoproducts ((6-4)PD) were determined in T7 DNA exposed to UV radiation under...

Assessment of the Effects of Various UV Sources on Inactivation and Photoproduct Induction in Phage T7 Dosimeter

The correlation between the biologically effective dose (BED) of a phage T7 biological dosimeter and the induction of cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts ((6-4)PD) in the phage DNA was determined using seven various UV sources. The BED is the inactivation rate of phage T7 expressed in HT7 units. The CPD and (6-4)PD were...

Expression of the Autographa californica nuclear polyhedrosis virus p10 gene: Effect of polyhedrin gene expression

Two major late proteins, polyhedrin and p10, are synthesized in large quantities in baculovirus infected insect cells. This and the fact that both proteins are dispensable for virus replication, form the basis for the use of these viruses as vector for foreign gene expression. To address the question whether the Autographa californica nuclear...

Structural and functional analysis of two cryptic plasmids from Lactobacillus pentosus MD353 and Lactobacillus plantarum ATCC 8014

The DNA sequences of a 2.4 kb plasmid (p353-2) from Lactobacillus pentosus MD353 and a 1.9 kb plasmid (p8014-2) from Lactobacillus plantarum ATCC 8014 show 81.5% overall similarity. Both plasmids carry elements (replication protein gene, plus-origin and minus-origin of replication), which are typical of plasmids that replicate via a rolling...

Leukaemia virus infection promotes fibroblast transformation by normal BALB/c mouse DNA

All normal cells are thought to carry genetic information for oncogenic transformation, which, on activation to continuous expression. might make the cell cancerous. The presently known transforming retroviruses contain transforming genes which were probably derived by recombination of a slow oncogenic retrovirus with cellular sequences closely...

Induction of mutations in bacteriophage T7 by gamma-rays. No influence of the SOS repair pathway

Under conditions where the reversion of an amber mutant of bacteriophage ?? by ??-rays is enhanced by subjecting the irradiated phage to SOS repair, ??-ray-induced reversion of two T7 ambers is not influenced by this error-prone bacterial repair system. The survival of T7 ??-irradiated under anoxic conditions is somewhat enhanced by SOS repair,...

Gamma-Ray mutagenesis in bacteriophage T4 is not enhanced by oxygen

As in the induction of r mutants in bacteriophage T4 by ??-rays, the radiation-induced reversion of T4 amber mutants to wild-type was found to depend on the product of the DNA-repair gene x of the phage. Neither the efficiency of induction of r mutants nor the efficiency of reversion of ambers was enhanced by the presence of oxygen during...

Gamma-ray induced double-strand breaks in DNA resulting from randomly-inflicted single-strand breaks: Temporal local denaturation, a new radiation phenomenon?

The induction of single- and double-strand breaks in DNA by γ-rays has been measured. The maximum number of nucleotide paris (a) between two independently induced single-strand breaks in opposite strands of the DNA which cannot prevent the occurrence of a double-strand break was found to amount to about 16. This value did not differ...

Mechanisms of inactivation of bacteriophage phiX174 and its DNA in aerosols by ozone and ozonized cyclohexene

The mechanisms of inactivation of aerosolized bacteriophage phiX174 in atmospheres containing ozone, cyclohexene, or ozonized cyclohexene were studied by using 32P-labelled phage. The inactivation of the aerosolized phage in clean air or in air containing cyclohexene is due to damage of the protein coat since the deoxyribonucleic acid (DNA)...

Induction of mutations in bacteriophage T7 by γ rays: Independence of host repair mechanisms

Amber mutants of bacteriophage T7 are reverted by γ-rays to pseudo wild-type particles, i.e. particles able to propagate in a suppressorless host. The yield of revertants is much higher when the phage is irradiated in the presence of oxygen than when irradiated anoxically. Under particular gas conditions the efficiency of mutation induction...

The effect of irradiation with ultraviolet light on the sedimentation behaviour of PM2 DNA

Chemicals/CAS: DNA, Viral

Radiosensitization of biologically active DNA in cellular extracts by oxygen. Evidence that the presence of SH compounds is not required

The radiosensitization by oxygen of biologically active bacteriophage DNA in bacterial extracts was studied. The oxygen effect in such a system appeared not to be due or only to a minor extent to the presence of endogenous sulphydryl compounds. The components in a cell extract which enable oxygen and other sensitizers to sensitize DNA could not...

Influence of the radiosensitizers paranitroacetophenone and triacetoneamine N oxyl on the effects of ionizing radiation on DNA

Paranitroacetophenone (PNAP) and triacetoneamine N oxyl (TAN), which sensitize anoxic cells to ionizing radiation, do not increase the radiosensitivity of bacteriophage DNA irradiated in the dry state, showing that the 'direct action model' of sensitization does not hold in this experimental set up. PNAP and TAN added within 1.5 msec after...

Infection of spheroplasts of Pseudomonas with DNA of bacteriophage PM2

Spheroplasts of Pseudomonas BAL-31/PM2, obtained by treatment of the bacteria with lysozyme, can be infected with purified DNA from bacteriophage PM2. After 4 h of incubation the yield of progeny phage reaches a value of 107-6×107 plaque forming units/μg PM2 DNA. The yield increases linearly with the concentration of DNA over at least 3 orders...

Thermal inactivation of bacteriophage _X174 and two of its mutants

The thermal inactivation of the two forms (∅* and ∅) of bacteriophage ∅X174 with different adsorption properties was investigated under various conditions of pH, ionic strength, and temperature. A reaction mechanism is proposed that is similar for both forms. At high temperatures inactivation occurs mainly as a result of protein destruction and...