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G Rontó

Publications and source records attributed to G Rontó.

34 records · Page 2Linked to original sources
PubMed1982

Temperature dependent structural changes of intraphage T7 DNA.

The phenomena connected with the first phase transition step of the native T7 phage at 40 degrees-65 degrees C have been studied using various methods. In this temperature range a) the optical melting curve shows an absorption decrease, b) the maximum of the small-angle X-ray scattering characteristic for DNA packing disappears, c) there is a drop of biological activity and d) there are changes in the structure of the difference absorption spectra of native phages versus isolated DNA. All data are interpreted assuming a structural change of the DNA due to the release of its protein coat towards the end of the first phase transition step (at 60 degrees-65 degrees C in the case of M9 buffer). Above this temperature the intraphage DNA packing appears to be destroyed and the DNA structure seems to be similar to that in DNA solution.

DNA, Viral↗
PubMed1979

Determination of the biological parameters of bacterium-phage complexes.

The authors present a method of measurement and evaluation for continuous cultures of bacteria infected by virulent phages. By the comparison of the model describing the phage-bacterium interaction and their own experimental data they determined the following biological parameter values characterizing the interaction: the adsorption rate (mu), the expectation of the latency period (T) and its standard deviation ((sigma), the time required for lysis (d), the infection efficiency (eta) and the average burst size (C). The parameters were used for the determination of optimal cultivating conditions (maximum phage yield).

Adsorption↗
PubMed1975

Inactivation of bacteriophages T7 and phiX174 by radiomimetics.

Inactivation of phages T7 and phiX174 induced by the radiomimetics N-nitroso-N-methylurea (NMU) and N-acetylethylenimine (AEI) has been studied. In semilogarithmic scale the kinetic curves of phage inactivation were steplike in character. This was connected with the occurrence of several processes in the system. A possible kinetic model has been proposed for the process of NMU-induced phage inactivation. The model is applicable to initial phage inactivation only. From the model a kinetic curve parameter, rho can be determined which characterizes the radiomimetic effect on different phages and determines the changes in the repair system after caffeine treatment. NMU exerted a post-inactivation effect on the phage T7. Also the NMU-induced phage T7 post-inactivation kinetic curves were of steplike character. They can be described as a sum of two exponential processes of different rate constant. The rate constant for the first stage of the post-inactivation process was close to the depurinization rate constant found in the literature.

Azirines↗
PubMedDate not supplied

Influence of spectral and angular sensitivity on the readout of biological dosimeters.

Biological systems used as biological dosimeters can possess different angular sensitivities from the detectors usually used in physical devices. A simple experimental setup has been developed and used to measure the angular sensitivity of uracil thin-layer biological dosimeters. Results of angular sensitivity measurements for uracil thin-layer dosimeters are presented using a Xe arc lamp as the UV source. According to the experiments described here, uracil thin-layer dosimeters show a cosine-type angular dependence. In several indoor experiments broadband UV meters are used to control the applied dose rate from a given artificial UV source. The experimental setup has been designed and used to verify experimentally the importance of spectral and angular sensitivity differences of biological and physical UV meters applied in biological experiments. Model calculations for two different irradiation systems, using different geometrical arrangements of artificial UV sources, are also presented. For these arrangements relative dose rates that could be measured with dosimeters of arbitrary spectral, but different angular sensitivity have been calculated.

Dimerization↗
PubMedDate not supplied

Biological UV dosimeters in the assessment of the biological hazard from environmental radiation.

To determine the impact of environmental UV radiation, biological dosimeters that weight directly the incident UV components of sunlight have been developed, improved and evaluated in the frame of the BIODOS project. Four DNA-based biological dosimeters ((i) phage T7, (ii) uracil thin layer, (iii) spore dosimeter and (iv) DLR-biofilm) have been assessed from the viewpoint of their biological relevance, spectral response and quantification of their biological effectiveness. The biological dosimeters have been validated by comparing their readings with weighted spectroradiometer data, by comparison with other biological doses, as well as with the determined amounts of DNA UV photoproducts. The data presented here demonstrate that the biological dosimeters are potentially reliable field dosimeters for measuring the integrated biologically effective irradiance for DNA damage.

Bacillus subtilis↗