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

Bleichrodt, J.F. (author), Roos-Verheij, W.S.D. (author), Medisch Biologisch Laboratorium TNO (author)

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,...

article 1980

document

Influence of SOS repair on the specificity of radiation mutagenesis in bacteriophage phiX174

Bleichrodt, J.F. (author), Roos-Verheij, W.S.D. (author), Medisch Biologisch Laboratorium TNO (author)

article 1979

document

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

Bleichrodt, J.F. (author), Roos-Verheij, W.S.D. (author), Medisch Biologisch Laboratorium TNO (author)

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...

article 1979

document

Mean tropospheric residence time of cosmic-ray-produced beryllium 7 at north temperate latitudes

Medisch biologisch laboratorium TNO (author), Bleichrodt, J.F. (author)

article 1978

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

Bleichrodt, J.F. (author), Roos, A.L.M. (author), Roos Verheij, W.S.D. (author), Medisch Biologisch Laboratorium TNO (author)

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...

article 1977

document

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

van Hemmen, J.J. (author), Meuling, W.J.A. (author), Bleichrodt, J.F. (author), Medisch Biologisch Laboratorium TNO (author)

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...

article 1974

document

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

van Hemmen, J.J. (author), Meuling, W.J.A. (author), Bleichrodt, J.F. (author), Medisch Biologisch Laboratorium TNO (author)

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...

article 1973

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Reversion of cistron A amber mutants of bacteriophage phiX 174 by ionizing radiation

Bleichrodt, J.F. (author), Verheij, W.S.D. (author), Medisch Biologisch Laboratorium TNO (author)

Amber mutants of bacteriophage can be reverted by ionizing radiation to pseudo wild type particles, i.e. particles able to propagate in a suppressorless host. Since the DNA of phi X 174 is single stranded mutation cannot be due to errors in repair of radiation damage by the excision repair or by the recombination repair system of the host cell,...

article 1973

document

Infection of spheroplasts of Pseudomonas with DNA of bacteriophage PM2

van der Schans, G.P. (author), Weyermans, J.P. (author), Bleichrodt, J.F. (author), Medisch Biologisch Laboratorium TNO (author)

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...

article 1971

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On the origin of the 70 S component of bacteriophage ∅X174

Bleichrodt, J.F. (author), Knijnenburg, C.M. (author), Medisch Biologisch Laboratorium TNO (author)

article 1969

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Bacteriophages related to ∅X174 showing a transition between two forms with different heat sensitivity and adsorption behavior

Bleichrodt, J.F. (author), Berends-Van Abkoude, E.R. (author), Medisch Biologisch Laboratorium TNO (author)

article 1968

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Thermal inactivation of bacteriophage _X174 and two of its mutants

Medisch Biologisch Laboratorium TNO (author), Bleichrodt, J.F. (author), Blok, J. (author), Berends-Van Abkoude, E.R. (author)

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...

article 1968

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The transition between two forms of bacteriophage φX17A differing in heat sensitivity and adsorption characteristics

Bleichrodt, J.F. (author), van Abkoude, E.R. (author), Medisch Biologisch Laboratorium TNO (author)

If cells of the bacterium Escherichia coliC infected with bacteriophage φX174 are lysed artificially in the cold, the phage obtained is relatively heat resistant at temperatures around 65° and unable to adsorb to host cells at 4°. At 37° the phage particles become more thermolabile with respect to inactivation at 65° and, concomitantly, obtain...

article 1967

document

Remarks on paper by P. J. Drevinsky, a.o.: Be7, P32, P33, and S35: stratospheric concentrations and artificial production

Medisch Biologisch Laboratorium TNO (author), Bleichrodt, J.F. (author)

article 1964

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Artificial beryllium 7 in the lower stratosphere

Medisch Biologisch Labortorium TNO (author), Bleichrodt, J.F. (author), van Abkoude, E.R. (author)

article 1963

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On the deposition of cosmic-ray-produced beryllium 7

Medisch Biologisch Labortorium TNO (author), Bleichrodt, J.F. (author), van Abkoude, E.R. (author)

article 1963

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Increased concentration of beryllium-7 in the stratosphere after the nuclear test explosions during September-October 1961

Bleichrodt, J.F. (author), Medisch Biologisch Laboratorium TNO (author)

IN their work on cosmic-ray-produced beryllium-7 in rain water at tropical latitudes during the period 1955-59, Rama, Zutshi and Lal1-3 did not find evidence of the production of this nuclide by nuclear test explosions. Since beryllium-7 in air and rain water is measured in several laboratories in order to obtain information on atmospheric...

article 1962

document

Origin of radioactive fallout in the Northern hemisphere after the Spring maximum in 1959

Medisch Biologisch Laboratorium TNO (author), Bleichrodt, J.F. (author), Blok, J. (author), van Abloude, E.R. (author)

article 1961

document

On the spring maximum of radioactive fallout from nuclear test explosions

Medisch Biologisch Laboratorium TNO (author), Bleichrodt, J.F. (author), Blok, J. (author), Dekker, R.H. (author)

article 1961

document

Changes in the radioactivity regime during the passage of a cold front over The Netherlands

Bleichrodt, J.F. (author), Bleeker, W. (author), Schmidt, F.H. (author), Medisch Biologisch Laboratorium TNO (author)

article 1960