Polarographic study of quinones formed during oxidation of caffeic and chlorogenic acids]

Polarographic behaviour of a number of substituted ortho-benzenquinones was studied in weakly acidic, neutral and weakly caustic solutions (up to pH --9.0). Half-wave potential depends on the solution pH, indicating protonization of the carbonyl groups of the quinones. Protonization is probably stipulated by the hydroxonium ions. Protonization may take place not only under the action of water, but also under the effect of other acidic components, as indicated by the dependence of E1/2 on the undissociated acetic acid centrifugation. The condensation and polymerization reactions are characteristic for the ortho-quinones. A shift of the quinone potential indicates dimerization of the electrode products.     

Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.     

Polymerase chain reaction with universal primers for studying genomes]

Universal primer ability of generating conservative and variable UP-PCR (universally primed polymerase chain reaction) species-specific patterns was analysed on bacteria to serve as an example. Also, two important properties of the UP-PCR patterns (species/primer DNA hybridization specificity) are characterized.     

Idiotype-specific inactivation by xenogeneic antisera of T killers but not of T-MIF producers immune to H-2 complex antigens

Following appropriate absorption rabbit serum to CBA anti-C57BL/6 lymph node cells (rabbit ISS) and rat serum to enriched CBA anti-C57BL/6 T killers (rat ISS) selectively inhibited the activity of K-anti-b T killers but did not affect T killers of other specificities (K-anti-d, d-anti-b). Rabbit ISS did not suppress the capacity of CBA anti-C57BL/6 (K-anti-b) T cells to produce MIF. Under the same conditions, anti-Thy-1.2 serum inactivated killers and K-anti-b MIF-producers. The findings indicate that the killers and MIF-producers immune to the antigens of H-2 complex constitute different subpopulations of T cells, which appear to carry nonidentical sets of idiotypes.     

Possibility spaces and evolution

Regulatory sequences, protein active sites, and gene networks contain evolutionarily conservative modules, which define possibility spaces, which restrict variability and canalize evolution. This provides a new insight into Vavilov’s law of homologous series and other cases of parallel evolution. These modules are self-sustained due to duplications and convergent molecular evolution. At the same time, protecting some mutations from the effect of natural selection, the modules facilitate accumulation of mutations in the quasineutral mode and, thereby, promote further evolution, making it unique.     

Relation of double-stranded DNA breaks and their repair to cell death and recovery after methylnitrosourea exposure

The yield of DNA double-strand breaks (DSB) in the cells of mouse lymphosarcoma treated with nitrosomethylurea (NMU) was registered by means of elastoviscosimetry. It was shown that after short-term (7 min) treatment with NMU the lesions formed in DNA are efficiently repaired both in complete and conditioned media. After long-term (30 min) treatment DNA was only repaired in complete growth medium. The yield of the first fixed DSB after long-term NMU treatment correlated with the mean lethal dose D0. After short-term NMU treatment the first DSBs are registered in the dose range which is 4-fold higher than D0. The nature of lethal and potentially lethal lesions as well as the participation of various repair systems in the elimination of potentially lethal lesions are discussed.