Amplitude-time parameters of long-latency components (N1, N2 and P300) of acoustic evoked potential of healthy examinees of young and mature age

The aim of study was to track a cumulative changes of amplitude-time parametres of components N1, N2 and P300 of acoustic evoked potential in experimental situations different in complexity (at the account and listening of sounds) and to compare the received distinctions at examinees of young and mature age. ERP were recorded at 12 healthy subjects from 18 to 22 ages and 12 subjects from 32 to 59 ages. The two-stimuli oddball paradigm was used. It is revealed that components N1, N2 and P300 recorded in the situation of the listenings of sounds without any preliminary instruction do not differ at persons of young and mature age. At examinees of younger age the biger amplitude of component N1 is noted at the account of sounds in comparison with listening whereas the latency of the one do not change depending on complexity of the task. It is shown that component N2 has stability of latency in relation to age and an experimental situation. The amplitude of component N2 is above at the account of sounds in both age groups. The amplitude-time parametres of component P300 do not differ at examinees of different age in a problem of listening of sounds. The revealed features of components N1, N2 and P300 at examinees of young and mature age in experimental situations different in complexity, allow to assume that with the years at the person adaptive mechanisms which allow carrying out successfully of the task.     

Optimization of the nutrient medium makeup for the biosynthesis of carminomycin using mathematical methods of experimental design]

The nutrient medium for biosynthesis of carminomycin by Actinomadura carminata, strain 4281 was optimized with the methods of mathematical planning of the experiment. The starting variant of the medium, production of carminomycin on which was assumed equal to 100 per cent was enriched during the experiments carried out according to the patterns of the orthogonal latin squares. The production levels of carminomycin on the above medium was more than 3 times higher than those on the starting medium.     

Genetic study of Escherichia coli K-12 mutations that affect the transposition process

Results of genetic analysis of bacterial tnm mutations influencing transposition of Tn9 are presented. Five independent tnm mutations were mapped at 90,5 min of the E. coli genetic map. The tnm mutations were 3,5 and 46,5% contransducible with metA and malB markers, respectively. Two tnm mutations tested were recessive in tnm+/tnm- merodiploids. The effect of tnm mutations on other transposons--Tn10, Tn601, Tn3 and Tn5 was examined. It was shown that tnm1 and tnm2 mutations reduced the frequency of transposition of Tn10, Tn3, Tn5 and Tn601 from the genome of phage lambda and inhibited intracellular development of the infecting Mu phage. The latter effect was probably due to the inhibition of Mu integration into bacterial chromosome. The tnm3 mutation affected the transposition of Tn9 only.     

The motor activity of the chick embryo and amnion during embryogenesis

Studies have been made on the motor activity of amnion and chick embryo from the 5th to the 14th day of development. Between the 5th and the 8th day of embryogenesis, when embryonic movements are rather poor, amnion contractions are mainly observed, their frequency being maximum to the 7th day. On further development (8-14 days), with the increase in the mass of the limbs which account for embryonic movements (body extremities), the increase in the intensity of their motor activity is paralleled by the decrease in the frequency of amnion contractions. Therefore, during the intensive growth and development of mainly frontal part of the embryo, the deficiency of motor activity of rather undeveloped body and extremities is presumably compensated by temporal motor activity of the amnion. Between the 8th and the 10th day, synchronous movements of embryo and amnion are observed. Possible mechanisms of synchronization are discussed.     

Interaction of negative (CytT) and positive (cAMP-CRP) regulation in the promoter region of the uridine phosphorylase (udp) gene in Escherichia coli K-12

Interaction of negative (CytR) and positive (cAMP-CRP) control in the promoter region of the uridine phosphorylase (udp) gene of Escherichia coli has been studied by using udp-lac operon fusions in which the structural lacZ gene is expressed from the wild type promoter udpP+ or from mutant promoters udpP1 and udpP18. The specific activity of beta-galactosidase was examined in these fusions in cytR+ and cytR- backgrounds after introduction of specific mutations in crp locus, crp* and crp(a) altering interaction of CRP protein with catabolite-sensitive promoters. The data obtained using crp* mutation confirm the proposed model of the udp gene regulation, according to which CytR repressor protein interferes with CRP binding site in the promoter-operator region of the udp gene and thereby prevents the positive action of cAMP-CRP complex on the udp expression. Additional data in favor of this model were obtained using crp(a) mutation which most probably alters the structure of CRP protein in such a way that it exhibits more high affinity to the udp promoter, as compared to the CytR repressor protein. Indeed, taken by itself, the crp(a) mutation did not lead to any increase in the expression of udpP+-lac fusion under the conditions of cAMP limitation (on glucose-grown cells), in spite of whether or not the CytR repressor was present. However, when combined with the ptsG mutation or when cells were grown on succinate medium, complete constitutive expression of udpP+-lac fusion is observed, even in the presence of the cytR gene product. The effect of the crp(a) mutation was virtually the same in strains harboring udpP1-lac fusion. These data are in accordance with suggestion that udpP1 is a mutation in the site of the promoter-operator region that responds to the cytR gene product, while the corresponding binding site for CRP protein is still unaltered in this mutant. On the other hand, the crp(a) mutation causes only slight alteration in the expression of udpP18-lac fusion, providing additional evidence that udpP18 mutation seems to comprise a modification of the promoter-operator region, where binding sites for CRP and CytR proteins overlap.     

Aftereffect of synchronizers of protein synthesis rhythm in hepatocytes in vitro

The effect of gangliosides and phenylephrine synchronizing the protein synthesis rhythm was preserved in hepatocytes cultured in the normal serum-free medium for one-two days. Hence, the membrane signal triggers intracellular, as was shown by us earlier, calcium-dependent processes, which regulate the kinetics of protein synthesis for a certain time after the signal perception.     

Effect of hypoxia on amnion rhythmic contractions and heart rate in the embryonic European pond turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

The effect of acute hypoxia (10% O₂ for 30 min) on the rate of amnion rhythmic contractions and heart rate (HR) was studied in two age groups of European pond turtle (Emys orbicularis) embryos, on days 19–27 and 37–43 of incubation (30–40 and 60–70% of the period until hatching). Under the control conditions, the two age groups of embryos did not differ from each other in either parameter. Hypoxia did not affect significantly the amnion contraction frequency but decreased the HR. The time course of the HR during hypoxia depended on the embryo age. The mean HR in the first group of embryos was 8% decreased by minutes 10–14 of hypoxia and did not change afterwards; in the second group, it was 18% decreased by minutes 3–7 and then partly or completely restored before the end of hypoxic exposure. It has been assumed that the capacity of European pond turtle embryos for restoring the HR when exposed to acute hypoxia during the second half of embryogenesis is related to the development of neurohumoral control mechanisms.     

Growth and oxygen consumption in embryonic and early postembryonic development of European pond turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Experiments on developing eggs of European pond turtle (Emys orbicularis) demonstrated S-shaped changes in the rate of oxygen consumption and body weight during embryonic development. The rate of oxygen consumption and weight progressively increased within 70 days after hatching. During embryogenesis, the mass-specific rate of oxygen consumption decreased. After hatching, it increased but then decreased to a certain level, which remained constant to the end of the studied period. We observed unidirectional changes in the mass-specific rate of oxygen consumption and specific weight gain during embryonic development and this pattern was maintained after hatching. The coefficients of the allometric relationship between oxygen consumption and body weight were a = 0.33 and k = 0.52 during embryonic development and a = 0.17 and k = 0.89 during postembryonic development.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 2, 2005, pp. 214–220.Original Russian Text Copyright © 2005 by Vladimirova, Alekseeva, Nechaeva.     

Age-related features of protein synthesis rhythm in hepatocytes. Effects of extracellular medium

Cell interactions have been studied in cultures pf hepatocytes from young and old rats. The rhythm of protein synthesis is an index of cell interaction and synchronization in culture, while the amplitude of oscillations characterized cell cooperation in an aggregate rhythm. The mean rhythm amplitude in the culture of hepatocytes from old rats is twice lower than that from young rats. Gangliosides (mixture, bovine brain gangliosides) and alpha1-adrenomimetic phenylephrine enhanced synchronization of cultures of the cells from old rats and increased the amplitude of oscillations to the level of young animals. Addition of rat blood serum (10%) to the medium revealed the rhythm of protein synthesis in the culture, asynchronous in the control, i.e., led to their synchronization. In media with young and old rat blood sera, oscillations were intense, with high amplitudes, and low, respectively. Addition of bovine brain gangliosides to a medium with old rat blood serum increased the amplitudes of oscillations to a level of the rhythm stimulated by the young rat serum. Thus, the cells of old animals can fully perceive synchronizing factors and, in the case of their increased concentration, the rhythm of protein synthesis in old animals did not differ from that in young rats. Current data on biochemical mechanisms underlying intercellular cooperation in the formation of population rhythm of protein synthesis have been discussed.