Role of catalase and superoxide dismutase in the yeast Saccharomyces cerevisiae response to hydrogen peroxide in exponential phase of growth

The role of catalase and superoxide dismutase (SOD) in response of the yeast Saccharomyces cerevisiae to oxidative stress induced by hydrogen peroxide in the middle-exponential phase has been investigated. It was shown that cell survival is significantly decreased after yeast exposure to hydrogen peroxide in the strains defective in cytosolic or peroxisomal catalases. Treatment of the wild-type cells with 0.5 mM H2O2 for 30 min causes an increase in the activity of catalase and superoxide dismutase, but the effect was not observed in all strains investigated. It was also shown that hydrogen peroxide leads to an increase in the activities of both catalases and Cu,Zn-containing SOD. The effect was cancelled by cycloheximide, an inhibitor of protein synthesis.     

Kinetics of rearrangement of solvation sheath of an excited molecule of the fluorescent probe 4"-dimethylaminochalcone

Processes accompanying the quenching of the fluorescent probe 4"-dimethylaminochalcone by hydroxyl groups of the proton-donor solvent 1-butanol have been studied. The kinetics of the deactivation of the excited state of 4"-dimethylaminochalcone has been monitored from the transition absorption spectra at a time resolution of 50 fs and fluorescence decay at a time resolution of 30 ps. The data obtained allow thinking that the next picture occurs in 1-butanol. At first stage, the 4"-dimethylaminochalcone molecule in its ground state forms a hydrogen bond with an alcohol molecule. At the second stage, the absorption of light quantum and corresponding rise of the dipole moment of 4"-dimethylaminochalcone take place, the initially existing hydrogen bond is retained. The third stage consists in the rearrangement of the 4"-dimethylaminochalcone solvation shell formed by alcohol dipole molecules due to an increase of the dipole of moment 4"-dimethylaminochalcone; this rearrangement takes an energy of about 24 kJ/mol, the arrangement time constant is close to 40 ps; the initial hydrogen bond is retained. The fourth stage involves processes that lead to fluorescence quenching; their time constant is about 200 ps. Taking into account that the quenching is a much slower process than the relaxation of the solvation shell, it was supposed that the quenching is not a direct consequence of the solvation shell relaxation or the existence of the hydrogen bond formed prior to excitation. Then the fluorescence quenching of 4"-dimethylaminochalcone can be accomplished through some other processes that are observed in other fluorescent molecules: (a) rearrangement of the initial hydrogen bond from a conformation that cannot quench the fluorescence of 4"-dimethylaminochalcone to a more "effective" conformation, (b) charge transfer between the excited of molecule 4"-dimethylaminochalcone and alcohol, or (c) solvent-induced twist of the 4"-dimethylaminochalcone amino group (its withdrawal from the molecule plane) by the action of the solvent.     

EDAS, databases of alternatively spliced human genes

EDAS, a database of alternatively spliced human genes, contains data on the alignment of proteins, mRNAs, and EST. It contains information on all exons and introns observed, as well as elementary alternatives formed from them. The database makes it possible to filter the output data by changing the cut-off threshold by the significance level. The database is accessible at http://www.gene-bee.msu.ru/edas/.     

Antinociceptive properties of the 5-HT3 receptor antagonist in the model of inflammatory pain in rats of different age with prenatal deficit of serotonine and under stress

The role of peripheral 5-HT3 receptors in the nociceptive behavioral response and the effect of the 5-HT3 antagonist ondansetron on indices of acute and tonic pain were investigated in the formalin test in 25- and 90-day-old Wistar male rats. The experimental rats were prenatally exposed to 5-HT depletion (a single injection ofparachlorophenilalanine 400 mg/kg/2 ml, i. p.; ICN, USA to the dams on day 9 of pregnancy) and to stress (dams immobilization during the last week of pregnancy). Antinociceptive effects of ondansetron in the rats with both prenatal 5-HT deficiency and stress (experimental rats) and prenatal injection of saline solution and stress (control rats) were more obvious in the younger animals. Prenatal 5-HT deficiency attenuated the antinociceptive effect of ondansetron in licking patterns in the younder age group in acute pain, and in adults--in tonic pain. Thus, the data obtained in the rats with prenatal 5-HT deficiency and stress indicate involvement of 5-HT3 receptors in mediation of prolonged pain in the formalin test, and antinociceptive effect of ondansetron which is attenuated in animals with prenatal 5-HT deficiency and specifically depends on rat's age.     

Double strand DNA breaks in C57B1 and mdx mice cardiomyocytes after dynamical stress

The survival of cardiac myocytes under different physiological and pathological conditions presents pressing problem. mdx mice cardiac myocytes are a promising model of cell survival under condition of oxidative stress. Our early results have shown that some part of mdx mice cardiomyocytes is in early stage of apoptosis (Kazakov, Mikhailov, 2001). But the development of cell death with loss of apoptotical cardiac myocytes occurs only after dynamical stress (bathing during 5 min) (Mikhailov et al., 2001). DNA endonuclease activity in the myocardium and low level of cardiac myocytes death during usual being of mdx mice allowed us to suggest DNA repair to be involved in the survival of mdx mice cardiac myocytes (Mikhailov et al., 2003). To confirm the suggestion we have studied the dynamics of formation and elimination of double strand DNA breaks in mdx myocardium cells after 5 min bathing at 12 degrees C. To visualise double strand DNA breaks formation cell nuclei were stained by monoclonal antibodies to phosphorylated H2Ax histone and to mouse PAP. Double staining with monoclonal anti-H2Ax antibodies and monoclonal anti-a-actin antibodies were used to separate cardiac myocytes from other myocardial cell types. The results showed that during 40 min after stress the deal of H2Ax-positive nuclei in mdx myocardium cells grew up to 41.7 +/- 11.4 % as compared with the initial control level of 6.7 +/- 0.2 %. The number of H2Ax-positive nuclei in these cells decreased after 24 h to 5.7 +/- 0.2 %. The quantity of tagged myocardium cell nuclei in C57B1/6 mice after stress was negligible and did not go beyond 0.01%. Dynamical stress also induced the increase in the rate of 3H-Thymidine incorporation by mdx mice cardiac myocytes from 0.3 +/- 0.3 up to 2.9 +/- 0.5 %. There was not change in the rate of 3H-Thymidine incorporation by cardiac myocytes in C57B1/6 mice. The numbers of labelled nuclei before and after stress were 0.2 and 0.3 %, correspondingly. The number of 3H-Thymidine labelled mdx cardiac myocytes fell down up to 0.4 +/- 0.2 % within 24 h after stress; the level of labelled C57B1/6 cardiac myocytes did not change. We have concluded that 3H-Thymidine incorporation into cardiac myocytes nuclei and staining of these nuclei by monoclonal antiboies phosphorylated H2Ax histone after stress demonstrate rather DNA repair than cardiomyocytes entry into the cell cycle.     

Comparative study of the reactability of phosphoric acid residues in tRNA(Ser) and tRNA(Leu) from Thermus thermophilus

The reactivity of phosphates in the Thermus thermophilus tRNA(Ser) (GCU) and tRNA(Leu) (CAG) was studied using the ethylnitrosourea modification. It was shown that phosphates of nucleotides 58-60 (T loop), 20-22 (D loop), and 48 (at the junction of the variable and T stems) were poorly modified in both tRNAs. The most pronounced differences in the reactivity were observed for phosphates at the junctions of the variable stem with T-stem (47q, 49) and anticodon stem (45). This indicates differences in orientations of the long variable arm relative to the backbone in the tRNAs studied.     

Activity of the climbing fiber innervating various Purkinje cells

Low-amplitude potentials (10-130 microV) related to the action of a distant branch of the climbing fiber, which elicits complex spikes of the reference Purkinje cell were revealed by means of potential averaging synchronously with complex spikes of Purkinje cells in 10 out of 255 paired records of cerebellar Purkinje cells activity and extracellular field potentials at interelectrode distances of 200-1500 microns. These potential waves had a stable form in independent sets of data. In 3 out of 10 cases, the low-amplitude potentials included a slow (about 100 ms in duration) component. In one case, both test and reference electrodes recorded both simple and complex spikes of different Purkinje cells so that complex spikes of both cells were practically synchronous (conditional probability of complex spikes p = 0.97, onset time difference 0.54 ms). Thus for the first time in cerebellar physiology both simple and complex spikes activity of two Purkinje cells controlled by the same climbing fiber was recorded.     

Ontogenetic features of psychophysiological mechanisms of perception of speech emotional component in musically gifted children

Cerebral mechanisms of musical abilities were explored in musically gifted children. For this purpose, psychophysiological characteristics of perception of emotional speech information were experimentally studied in samples of gifted and ordinary children. Forty six schoolchildren and forty eight musicians of three age groups (7-10, 11-13 and 14-17 years old) participated in the study. In experimental session, a test sentence was presented to a subject through headphones with two emotional intonations (joy and anger) and without emotional expression. A subject had to recognize the type of emotion. His/her answers were recorded. The analysis of variance revealed age- and gender-related features of emotional recognition: boys musicians led the schoolchildren of the same age by 4-6 years in the development of mechanisms of emotional recognition, whereas girls musicians were 1-3 years ahead. Musical education in girls induced the shift of predominant activities for emotional perception in the left hemisphere; in boys, on the contrary, initial distinct dominance of the left hemisphere was not retained in the process of further education.