Evolution of the electron Langmuir oscillations in an inhomogeneous magnetized plasma

The conditions under which the energy of the electron Langmuir oscillations can escape from the plasma into vacuum are determined in the simplest model of a plane slab of an inhomogeneous cold magnetized plasma in a uniform magnetic field.     

Role of lipid peroxidation in changes in the structure of Ca-ATPase in skeletal muscle sarcoplasmic reticulum during hypercholesterolemia

Using the method of spin labels it was shown that in hypercholesterolemia (HCh), the following parameters decreased: the velocity of maleimide spin label binding to sarcoplasmic reticulum (SR) Ca-ATPase of rabbit skeletal muscles, the accessibility of spin-labeled thiol groups of the enzyme to potassium ferricyanide and sodium ascorbate, and the mobility of the Ca-ATPase molecule fragment to which the spin label was attached. In addition, intensification of lipid peroxidation was demonstrated in SR membranes. Supplementation of the high-cholesterol diet with alpha-tocopherol resulted in the decreased rates of lipid peroxidation in SR membranes and increased values of the above parameters relative to the values found under HCh. It is concluded that the effect of alpha-tocopherol in vivo on the structure of the Ca-ATPase proteolipid complex in HCh is due mainly to antioxidant properties of the diet-supplementing substance.     

Evaluation of the professional qualities of operators working with computer displays

The influence of spatio-temporal factors (spatial heterogeneity of distribution of the numbers sought for in the matrix of data, processes of learning and development of fatigue, periodic attention oscillations) of the character of solving the task of searching the numbers in a matrix of 176 three-figure numbers (16 lines, 11 columns) was studied in 39 operators. The possibility was shown to use the characteristics obtained for evaluation of professionally important abilities of an operator working at the display.     

Plasma processing of spent nuclear fuel by two-frequency ion cyclotron resonance heating

A previously developed method for analyzing the plasma processing of spent nuclear fuel is generalized to a plasma containing multicharged fuel ions. In such a plasma, ion cyclotron resonance heating of nuclear ash ions should be carried out in two monochromatic RF fields of different frequencies, provided that the fraction of ξ multicharged ions is small, ξ ≤ 0.1, a condition that substantially restricts the productivity of systems for processing spent nuclear fuel. Ways of overcoming this difficulty are discussed.     

Protective effect of alpha-tocopherol on the Ca2+-transport system of the sarcoplasmic reticulum membranes in hypercholesterolemia

The effect of antioxidant--alpha-tocopherol--on Ca2+-transporting system in sarcoplasmic reticulum (SR) of the rabbit skeletal muscles was studied in hypercholesterolemia (HC). alpha-tocopherol administration to animals with HC produced a break on the curve of temperature dependence of Ca-ATPase activity at about 20 degrees C, that disappeared in HC, increased the rate of "rapid" SH-group binding by thiol reagents, and normalized the level of unsaturated fatty acids in SR membranes without altering phospholipid content. It is suggested that the damage of Ca-ATPase in HC is mainly due to activation of lipid peroxidation.     

Segmental flexibility of single-, double-, and triple-stranded polyribonucleotides from the data of spin label method. Formation of the triple-stranded poly(A.A.U) polynucleotide helix

Segmental mobility dynamic peculiarities of poly(U), poly(A) and poly(C) synthetic polymers and their complexes were investigated by spin-label method. Imidazolide spin-label was introduced into 2'-oxi-groups of polymer ribose in correlation: one spin-label on 18-20 bases. Formation of complexes was observed by ESR spectra at two pH: 4.2 and 7.2. Segmental mobility of only single strand spin-labelled polymer segment and in the complex was evaluated by measuring rotational correlation time (tau) determined by dependence of distances between outer wide extrema in ESR spectra from solvent viscosity at different temperatures. It turned out that correlation time tau of single strand structures in a high degree depend on pH and temperature. For three strand structures abrupt increase of tau because of appearance of rigidity was observed. It is possible to evaluate part of triple complexes poly(U.A.A) and poly(U.U.A) existing in dynamic equilibrium depending on pH and temperature by the form of outer wide extrema. Adding of dye to complex of poly(U).poly(A) causes an increase of rigidity of the supermolecular structure. Quantitative characteristics of formed complexes were obtained by simulation of ESR spectra on computer.     

Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal

We have developed a new approach to the measurement of phylogenetic signal in character state matrices called relative apparent synapomorphy analysis (RASA). RASA provides a deterministic, statistical measure of natural cladistic hierarchy (phylogenetic signal) in character state matrices. The method works by determining whether a measure of the rate of increase of cladistic similarity among pairs of taxa as a function of phenetic similarity is greater than a null equiprobable rate of increase. Our investigation of the utility and limitations of RASA using simulated and bacteriophage T7 data sets indicates that the method has numerous advantages over existing measures of signal. A first advantage is computational efficiency. A second advantage is that RASA employs known methods of statistical inference, providing measurable sensitivity and power. The performance of RASA is examined under various conditions of branching evolution as the number of characters, character states per character, and mutations per branch length are varied. RASA appears to provide an unbiased and reliable measure of phylogenetic signal, and the general approach promises to be useful in the development of new techniques that should increase the rigor and reliability of phylogenetic estimates.      

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Some peculiarities of the dynamics of the immunoglobulin M structure

The isotropic mobility of separate regions of the intact molecule of immunoglobulin M (IgM) and its Fab and (Fc)5 fragments was studied using spin-labeling of carbohydrate (2,2,6,6-tetramethyl-4-aminopiperidine-1-oxyl) and peptide (2,2,5,5-tetramethyl-3-dichlorotriazinylaminopyrrolidine-1-oxyl) moieties. The spin-labeled oligosaccharide groups (OGs) in the Fab region are shown to have much more amplitude of anisotropic motion than those in the (Fc)5 region. The spin label in the latter is evidently attached in the C mu 3 domain to one of its OGs which is probably stabilized by ionic contacts between terminal N-acetylneuraminic acid residue and the peptide moiety of the IgM molecule. When the amount of the glycosidase-cleaved carbohydrate does not exceed 10-15%, most OGs affected are of the Fab region. Upon profound splitting (greater than or equal to 50%) the OGs of the (Fc)5 region are also affected; that results evidently in loosening the ionic contacts between the shortened OGs and the peptide moiety of IgM, and consequently in increasing mobility of the former. The structure of the (Fc)5 region of IgM is labile; after detaching this moiety from the intact IgM molecule, its structure is stabilized, but one of its domains (C mu 3) becomes more mobile than it is in the intact IgM molecule; at the same time the amplitude of anisotropic motion of OG bound here is decreased. In the latter case, this decrease depends on the sequence of spin-labeling and fragmentation. The most probable cause of stabilization of the (Fc)5 fragment is the heating of IgM solution to 56 degree C during fragmentation with trypsin. At this temperature the tau value for the (Fc)5 fragment is unusually low, equaling 23 ns. The spin-labeling in the peptide part of IgM occurs mostly in the Fab region which is a rather rigid moiety as expected.     

Comparative study of dynamic structure of pig and chicken aspartate aminotransferases by measuring the rotational correlation time

The rotational correlation time of two homologous cytoplasmic aspartate aminotransferase molecules isolated from pig and chicken hearts was obtained by spin-labeling technique. The maleimide and iodoacetamide spin-labels modyfying external SH-groups of a protein were used. In the interpretation of ESR spectra a rotational motion of nitroxide group relative to the protein molecule was taken into account. To determine the macromolecule rotational correlation time two methods of the immobilization of a protein molecule were used: 1) by means of increasing protein solution viscosity and 2) by fixation of the protein molecule on adsorbent. From comparison of experimental and theoretical values of rotational correlation time it was conclude that the both enzymes exhibits an intramolecular flexibility.