Structural state of active and inactive genes during chromatin decondensation

Chromatin structure of globin and ovalbumin genes in chicken erythrocyte nuclei has been investigated by means of the "nuclease criterion" (described earlier). In intact nuclei (i.e. in the presence of 3 mM MgCl2) DNase I cleaves chromatin of both genes generating fragments multiple of a double-nucleosome repeat (2N-periodicity). However, in the case of the globin gene, apart from the 2N-periodicity, fragments were observed that are multiple of 100 b.p. and are characteristic for partially unfolded chromatin. This distinction in nuclease cleavage patterns correlates with a higher sensitivity of the globin gene as compared with the inactive ovalbumin gene. At 0.5-0.7 mM MgCl2 the transition from dinucleosomal fragmentation with DNase I and DNase II to fragmentation via a 100 b.p. interval occurs and the difference in digestibility of both genes is dramatically increased. If chromatin has been decondensed by incubation of nuclei in 10 mM Tris-buffer DNase Il generates an usual nucleosomal repeat, and in this ionic conditions one may not observe any difference in nuclease sensitivity of the analyzed genes. The data allow to suggest that the high nuclease sensitivity of potentially active genes can be conditioned by more relaxed arrangement of nucleosomes in higher order chromatin structure.     

Performance of the Conventional Divertor in TRT

Plasma Physics Reports - The paper presents the first results of SOLPS4.3 modeling of the TRT divertor within the conventional paradigm: a single-null poloidal divertor with solid metal...     

Fluxes in DEMO-FNS Fuel Cycle Systems with Allowance for Injection of D and T Pellets

Plasma Physics Reports - As a result of self-consistent simulations using the ASTRA + SOLPS and FC-FNS codes, the range of parameters was found, within which the required fraction of tritium in the...     

Theoretical study of the pulse method for the quenching analysis of photosystem II fluorescence

The kinetics of photochemical (qQ) and nonphotochemical (qE) fluorescence quenching during induction was studied in terms of the earlier developed theoretical model of photosynthesis. Photochemical and nonphotochemical quenching was calculated from the parameters of fluorescence induction upon simultaneous excitation with continuous light and by high-intensity light pulses by the method used in a PAM fluorometer. It is shown that the fraction of closed reaction centers during the pulse can change in the course of induction. In consequence, even when none of supposed mechanisms of photochemical quenching is taken into account, the value of qE during induction varies and is not equal to zero.     

Effect of perfluorocarbon emulsions on function of enzyme systems responsible for generating active forms of oxygen in neutrophils

The ability of the emulsion of perfluoroorganic compounds stabilized with proxanol 268 to affect the functions of peritoneal neutrophils was evaluated. The functional activity of neutrophils was estimated from the intensity of generation of reactive oxygen species using the method of chemiluminescent analysis. The emulsion was shown to suppress the neutrophil responses to phorbol-12-myristate-13-acetate in a dose-dependent manner. No inhibition of the activity of neutrophils in the presence of the emulsion was observed in N-formylmethionylleucylphenylalanine stimulated cells. The data obtained indirectly confirm the suggestion that the perfluoride emulsion inhibits neutrophil NADPH oxidase activity. In the presence of the perfluoride emulsion, myeloperoxidase plays a more important role in the generation of luminescent responses in both N-formylmethionylleucylphenylalanine- and phorbol-12-myristate-13-acetate-stimulated neutrophils. The effect of perfluoride emulsion results in the preferential myeloperoxidase-produced generation of reactive oxygen species in the neutrophil respiratory burst.     

Characteristics of force-frequency relations in the myocardium of the squirrel Citellus undulatus

The force-frequency relationship (FFR) in papillary muscles of the heart of active ground squirrel in different seasons was studied. For comparison, similar preparations from rat and rabbit were used. It was shown that the FFR of papillary muscles of active ground squirrel undergo significant seasonal changes. In summer and a part of autumn squirrels, a negative staircase (a decrease in the isometric force with increasing stimulation frequency) similar to that in adult rat was revealed. The FFR of the majority of autumn, winter and spring squirrels were polyphasic and contained both positive and negative components. Changes in the force in response to the introduction of pauses at a constant stimulation frequency were recorded. Two types of the post-rest recovery pattern were revealed in the myocardium of ground squirrels. For frequencies range with the negative direction of FFR, a typical pattern of rest-potentiation similar to that in rat papillary muscles was observed. The amplitude of the first post-rest contraction (F1) was usually higher than that of the preceding steady-state contraction. In papillary muscles of autumn animals the F1 value was greater that in summer, which suggests an enhanced release of Ca2+ from the sarcoplasmic reticulum. There was no post-rest potentiation in the range of frequencies with positive direction of FFR, and the post-rest recovery pattern in these cases was principally different from those of rat and rabbit preparations. It was proposed that seasonal differences of the FFR of active ground squirrel heart are associated with changes in the ratio of activities of the calcium-transporting system in the hibernation period.     

Sorption of plasma components on the surface of particles of fluorocarbon emulsions stabilized by proxanol 268

It was found in the experiments in vivo and in vitro that the contact of perfluorocarbon emulsion stabilized with proxanol 268 with blood plasma leads to the sorption of various plasma proteins on the surface of emulsion particles. The profile of the proteins sorbed is complex and includes proteins with molecular weights ranging from 14 to 94 kDa. Among proteins sorbed on the emulsion particles circulating in blood, IgG was identified. Incubation of the emulsion stabilized with proxanol 268 with human blood plasma in vitro was shown to result in the sorption of IgG and IgA the perfluorocarbon particles. The sorbtion of serum proteins and immune complexes circulating in blood on the surface of perfluorocarbon particles stabilized with proxanol 268 was revealed to activate the complement system.     

Effect of dopamine antibodies on neuropathic pain syndrome in rats

Dopaminergic brain system plays an important role in regulation of pain sensitivity. However, the data on participation of antidopamine antibodies in the development of neurogenic pain are absent. This work was aimed at the study of the role of antidopamine antibodies in the development of pain syndrome induced by the injury of nn. ischiadic and saphenous in rats. It was shown that after the nerve injury, the behavioral reaction such as autotomy (self-injury) appeared as a feature of the experimental neuropathic pain syndrome. It was originally established that the development of neuropathic pain syndrome induced by the injury of peripheral nerves was accompanied by induction of dopamine autoantibodies. It was also shown that immunization of the animals with conjugated dopamine-protein autigen resulted in aninerease of autidopamine antibody level and an amplification of the experimental neuropathic pain syndrome, i.e., decrease in the latency of the first autotomy, increase in expression of autotomies, and increase in the number of animals with late autotomies.