The respiratory center--the regulator of the respiratory system

The authors consider the respiratory centre to be the regulator of the respiratory system and to consist of 3 main functional blocks: chemoregulator, respiratory rhythm autogenerator and mechanoregulator, functions of which are provided by the neurons of medulla oblongata. The main aim of chemoregulator block is to maintain the level of ventilation volume speed, which is necessary to compensate the difference between the signals of setting and the firing from the chemoreceptors. The main aim of mechanoregulator block is to provide the functioning of the regulation loop of the respiratory muscles comparing the signals which come from the respiratory autogenerator, and the firing of the mechanoreceptors. The generator unit of the respiratory centre is a set of rhythm-forming associations, the system of 4 neurons (early and late inspiratory and expiratory) are typical among them. The neurons are connected by recurrent inhibitory bonds: the neuron of each rhythm-forming group, successively becoming excited, inhibits the two preceding neurons in the cycle; for all this the neuron of the successive group is released from inhibition and in such a way the rhythmogenesis occurs. The respiratory centre forms a common unit for chemo- and mechanoreceptor loops, through which the circuits of feedback for both loops are connected, providing the regulation of breathing.     

Autonomic regulation and mental activity in children during school studies under unfavorable climatic conditions of the middle ob

Autonomic regulation and mental activity were studied in first-grade 7-year-old children under the Middle Ob climatic conditions. The study disclosed some features peculiar to adaptive alterations in children’s organisms and revealed both the degree of tension of the regulatory systems and changes in mental activity that described the “cost” of adaptation to school studies. Adaptation to school process depended on alteration of the regulatory mechanisms which had different expression at certain school periods and on changes in the relationship between sympathico-parasympathetic effects and the central regulation system, which were accompanied by different changes in mental activity. The adaptation mechanisms in most northern children were rather tense due to the unfavorable climatic effect on their organism.     

Burst discharges of a single nerve cell induced by korazol and penicillin

The electrical activity of an isolated stretch-receptor neuron of a crayfish was studied under the action of corazol and penicillin by microelectrode techniques. Burst discharges induced by these agents are found to have in their basis the depolarizing shifts of pacemaker origin.     

Assessment of TDDFT- and CIS-based methods for calculating fluorescence spectra of (dibenzoylmethanato)boron difluoride exciplexes with aromatic hydrocarbons

The applicabilities of various CIS- and TDDFT-based procedures to the calculation of the fluorescence spectra of DBMBF2 exciplexes with aromatic hydrocarbons are analyzed. It is shown that a reasonable agreement between the calculated and experimental fluorescence spectra is obtained when a combined procedure is used. In this combined procedure, the geometries of the exciplexes are optimized beforehand using the CIS method with an empirical dispersion correction, while the exciplex transition energies are calculated at the optimized geometries using the CIS(D) method or the TDDFT approach with double-hybrid B2PLYP and mPW2PLYP functionals.     

Cyclic nucleotide binding proteins in the <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> and <Emphasis Type="Italic">Oryza sativa</Emphasis> genomes

Background  

Cyclic nucleotides are ubiquitous intracellular messengers. Until recently, the roles of cyclic nucleotides in plant cells have proven difficult to uncover. With an understanding of the protein domains which can bind cyclic nucleotides (CNB and GAF domains) we scanned the completed genomes of the higher plants Arabidopsis thaliana (mustard weed) and Oryza sativa (rice) for the effectors of these signalling molecules.     

Determining the evolutionary potential of a gene

In addition to information for current functions, the sequence of a gene includes potential information for the evolution of new functions. The wild-type ebgA (evolved beta-galactosidase) gene of Escherichia coli encodes a virtually inactive beta-galactosidase, but that gene has the potential to evolve sufficient activity to replace the lacZ gene for growth on the beta-galactoside sugars lactose and lactulose. Experimental evidence, which has suggested that the evolutionary potential of Ebg enzyme is limited o two specific amino acid replacements, is limited to examining the consequences of single base- substitutions. Thirteen beta-galactosidases homologous with the Ebg beta-galactosidase are widely dispersed, being found in gram-negative and gram-positive eubacteria and in a eukaryote. A comparison of Ebg beta-galactosidase with those 13 beta-galactosidases shows that Ebg is part of an ancient clade that diverged from the paralogous lacZ beta- galactosidase over 2 billion years ago. Ebg differs from other members of its clade at only 2 of the 15 active-site residues, and the two mutations required for full Ebg beta-galactosidase activity bring Ebg into conformity with the other members of its clade. We conclude that either these are the only acceptable amino acids at those positions, or all of the single-base-substitution replacements that must arise as intermediates on the way to other acceptable amino acids are so deleterious that they constitute a deep selective valley that has not been traversed in over 2 billion years. The evolutionary potential of Ebg is thus limited to those two replacements.      

Studies on soybean seed proteins by means of disc electrophoresis

Three protein fractions (albumins, globulins and glutelins) of cotyledons of ripe and dormant soybean seeds were analysed by a modified polyacrylamide disc electrophoresis method. All fractions were shown to be multicomponent and easily characterized by their “protein electrophoresis spectra”. A method of characterizing proteins by their relative electrophoretic mobility (R.E.M.) by comparison with a new nontoxic dye as a tracer is employed for a preliminary identification of proteins. Specificity of protein complement was investigated in view of the autors, further studies on dynamics of specific proteins in the course of ripening and germination of soybean seeds.