Comparison of the aspartase activity and its stability in Escherichia coli cells immobilized on polyacrylamide gel and carrageenan

The conditions for immobilization of Escherichia coli cells (Soviet strain 85) on the natural polysaccharide carrier carrageenan (Soviet-made) were investigated and kinetic regularities of the aspartase reaction catalysed by immobilized in carrageenan cells of E. coli 85 were established. The conditions for retaining a high aspartase activity and stability of biocatalysts based on the E. coli 85 cells immobilized in PAAG and carrageenan were determined using full-loaded tanks for continuous synthesis of L-aspartic acid. The time-stable aspartase activity of the biocatalyst can be increased by treating the beads of the catalyst with bifunctional reagents (hexamethylenediamine, glutaraldehyde), the most active catalyst for the biotechnological synthesis of L-aspartic acid being obtained when carrageenan is used.     

Corynebacterium diphtheriae nontoxigenic strain carrying the gene of diphtheria toxin

Among 828 C. diphtheriae nontoxigenic cultures isolated in different region of Russia in 1994-2002, 114 cultures (13.8%) had the gene of diphtheria toxin (gene tox) and were thus called nontoxigenic tox-carrying (NTTC) strains. All NTTC strains were found to belong to biovar mitis and formed neither normal, nor "defective" diphtheria toxin. The most of NTTC strains (94%) belonged to ribotype "Moskva", not occurring among C. diphtheriae toxigenic strains. The incapacity of NNTC strains of forming diphtheria toxin was caused by mutation: the deletion of one nucleotide which led to the shift of the open reading frame and to the formation of the stop codon. The results of these studies are indicative of the fact that a sufficiently homogeneous and isolated group of C. diphtheriae nontoxigenic strains is spread in Russia. These strains carry the nonexpressing gene of diphtheria toxin and are of no epidemic importance in diphtheria infection.     

Quantification of sleepiness through principal component analysis of the electroencephalographic spectrum

Although circadian and sleep research has made extraordinary progress in the recent years, one remaining challenge is the objective quantification of sleepiness in individuals suffering from sleep deprivation, sleep restriction, and excessive somnolence. The major goal of the present study was to apply principal component analysis to the wake electroencephalographic (EEG) spectrum in order to establish an objective measure of sleepiness. The present analysis was led by the hypothesis that in sleep-deprived individuals, the time course of self-rated sleepiness correlates with the time course score on the 2nd principal component of the EEG spectrum. The resting EEG of 15 young subjects was recorded at 2-h intervals for 32-50 h. Principal component analysis was performed on the sets of 16 single-Hz log-transformed EEG powers (1-16 Hz frequency range). The time course of self-perceived sleepiness correlated strongly with the time course of the 2nd principal component score, irrespective of derivation (frontal or occipital) and of analyzed section of the 7-min EEG record (2-min section with eyes open or any of the five 1-min sections with eyes closed). This result indicates the possibility of deriving an objective index of physiological sleepiness by applying principal component analysis to the wake EEG spectrum.     

Seasonal activity budget of adult baltic ringed seals

Although ringed seals are important components in oceanic and fresh water ecosystems at high latitudes, little is known about how they exploit these harsh environments. Seasonal activity and diving behaviour of 19 adult Baltic ringed seals were studied by satellite telemetry. We elaborated an activity budget for ten months of the year, extending over the period from moult to the breeding season. Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks. Both the mean duration and the mean depth of dives peaked in June and July. Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn. Less than one percent of dives exceeded 10 min in females, while 10% of male dives lasted longer than 10 min in June to September. Less than one percent of dives lasted for more than 25 min. Both females and males were most active during day time and hauled out predominantly during the night. Activity patterns during the summer are suggested to be correlated to energy accumulation and prey availability. The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.     

Photoinduced bactericidal activity of TiO<Subscript>2</Subscript> films

A decrease in CFU of gram-positive and gram-negative bacteria on the surface of UV illuminated TiO₂ films (wavelength of 380 nm) is shown. A 29, 45, and 47% decrease in bacterial viability of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli, respectively, was seen after 12-min exposition. It was first discovered that the reuse of TiO₂ films to test a bacterial suspension for viability removes UV-induced bactericidal activity. However, annealing of TiO₂ at a temperature above 400°C restores the photoinduced bactericidal activity to its initial state.     

Enzymatic synthesis of L-malic acid from fumaric acid using immobilized Escherichia coli cells

Optimal conditions were chosen for cultivation of Escherichia coli 85 cells with a rather high fumarate-hydratase activity on a cheap medium containing no edible raw material. An active biocatalyst for the synthesis of L-malic acid from fumaric acid was obtained based on E. coli 85 cells immobilized in carrageenan. The enzymatic synthesis of L-malic acid from potassium fumarate was kinetically studied and optimized. Some thermodynamic parameters of fumaric acid hydration into malic acid were determined. A technique for assaying the reaction mixture was developed that involved high performance liquid chromatography.     

Biofeedback in optimizing psychomotor reactivity: II. The dynamics of segmental α-activity characteristics

To estimate the EEG predictors of successful training in the voluntary control of psychomotor reactivity, 29 healthy young (aged 22.3 ± 1.5 years) musical performers were examined. The estimation was carried out in terms of segmental α-activity analysis using a biofeedback session as an example, simultaneously stimulating the EEG α rhythm and decreasing the muscle tone. On the first day of the study, the musicians followed instructions for the voluntary control of comfortable finger motor activity when performing musical passages for the right hand during a standard performance practice (without any use of an adaptive feedback). On the second day, the muscle tone and the power of the EEG α rhythm were voluntarily controlled in the context of a biofeedback technology. The analysis of the unsteady EEG segmentation showed that the dynamics of changes in the coherence and segmental characteristics of the α activity were the same for both effective biofeedback training and the standard successful performance practice: an increase in the α-rhythm coherence, an increase in the lifetime of α spindles, and a decrease in their amplitude variability. The results obtained are discussed in terms of the formation and dissociation of neuron ensembles in central mechanisms of optimal psychomotor functioning.     

Photoinduced bactericidal activity of TiO2 films

A decline in CFU of gram-positive and gram-negative bacteria on the surface of UV illuminated TiO2 films (wavelength of 380 nm) is shown. A 29, 45, and 47% decrease in bacterial viability of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli, respectively, was seen following a 12-min exposition. It was first discovered that the reuse of TiO2 films to test a bacterial suspension for viability removes UV-induced bactericidal activity. However, annealing of TiO2 at a temperature above 400 degrees C restores the photoinduced bactericidal activity to its initial state.     

A new SWPAQ's scale predicts the effects of sleep deprivation on the segmental structure of alpha waves

The three-dimensional cube-in-globe model predicts the possibility to delineate six main adaptive abilities of the sleep - wake cycle (Putilov & Putilov, 2005). Such prediction led to the inclusion of a new sixth scale named “daytime wakeability” (Putilov & Putilov, 2006; Putilov, 2007) in the Sleep-Wake Pattern Assessment Questionnaire (SWPAQ; Putilov, 1990, 2000). This new scale permits self-assessment of the ability to keep waking at daytime in sleep provoking conditions. In the study reported here we applied the procedure of adaptive segmentation of the EEG record (SECTION 0.1®, Human Brain Research Group, Moscow State University) to determine whether sleep deprivation changes the temporal pattern of alpha activity and, if yes, whether this change is associated with state and trait self-measures of alertness/sleepiness including a score on “daytime wakeability” scale. In the course of sustained wakefulness, EEG was recorded nine times with three-hour intervals in frontal and occipital derivations in 39 healthy subjects. The procedure of adaptive segmentation allowed cutting EEG records on quasi-stationary segments and determining such characteristics of each segment as within-segmental amplitude, coefficient of its variation and segment length. These characteristics obtained in the morning hours on the first and second experimental days were compared. They were found to increase in the second morning, when eyes are open, but do not change when eyes are closed. It was also documented that “daytime wakeability” score along with other trait and state self-measures of alertness/sleepiness can serve as predictors of the response of alpha waves to sleep deprivation.     

Molecular characterization of podoviral bacteriophages virulent for Clostridium perfringens and their comparison with members of the Picovirinae

Clostridium perfringens is a Gram-positive, spore-forming anaerobic bacterium responsible for human food-borne disease as well as non-food-borne human, animal and poultry diseases. Because bacteriophages or their gene products could be applied to control bacterial diseases in a species-specific manner, they are potential important alternatives to antibiotics. Consequently, poultry intestinal material, soil, sewage and poultry processing drainage water were screened for virulent bacteriophages that lysed C. perfringens. Two bacteriophages, designated ΦCPV4 and ΦZP2, were isolated in the Moscow Region of the Russian Federation while another closely related virus, named ΦCP7R, was isolated in the southeastern USA. The viruses were identified as members of the order Caudovirales in the family Podoviridae with short, non-contractile tails of the C1 morphotype. The genomes of the three bacteriophages were 17.972, 18.078 and 18.397 kbp respectively; encoding twenty-six to twenty-eight ORF's with inverted terminal repeats and an average GC content of 34.6%. Structural proteins identified by mass spectrometry in the purified ΦCP7R virion included a pre-neck/appendage with putative lyase activity, major head, tail, connector/upper collar, lower collar and a structural protein with putative lysozyme-peptidase activity. All three podoviral bacteriophage genomes encoded a predicted N-acetylmuramoyl-L-alanine amidase and a putative stage V sporulation protein. Each putative amidase contained a predicted bacterial SH3 domain at the C-terminal end of the protein, presumably involved with binding the C. perfringens cell wall. The predicted DNA polymerase type B protein sequences were closely related to other members of the Podoviridae including Bacillus phage Φ29. Whole-genome comparisons supported this relationship, but also indicated that the Russian and USA viruses may be unique members of the sub-family Picovirinae.