V. I. Mel’nikova

The January 6, 2006, Balei earthquake as a reflection of the present tectonic activity of the east Trans-Baikal Region

The results of detailed studies of the January 6, 2006, Balei earthquake (Kp = 13.1, Mb = 4.7 [7]), which occurred in an almost aseismic area of the east Trans-Baikal Region, are presented. The focal mechanism and dynamical characteristics of the focus are considered, and the structural-tectonic position of the focus is analyzed. It is supposed that the focus of this seismic event coincides with an activated segment of the northwest-striking Balei-Darasun fault. The maximal observed macroseismic intensity was 5–6 points by the MSK-64 scale (in the town of Baleis). The origination of foci for the earthquake with such intensity and magnitude takes place substantially owing to subhorizontal northeastern compression, the varied-rank block structure of the medium, and low rate values of tectonic motions; on aggregate, all these factors promote the accumulation of stresses in the Earth’s crust. The obtained data can be useful for the purpose of assessment in seismic danger of the region.

Seismicity of the Baikal rift zone for the digital recording period of earthquake observation (2001–2006)

Some characteristics of the seismic regime of the Baikal rift zone for the analogue (1960–2000) and digital (2001–2006) registration modes are considered. It was ascertained that the general number of seismic events recorded by digital equipment increased by two times in comparison with the analogue observation period and the catalog completeness level was lowered to KP = 7.0 as well. The focal mechanisms of 110 earth-quakes with KP ≥ 8.0 were examined. The overwhelming majority of them during 2001–2006 were due to normal faulting and normal faulting with strike-slip components. Special attention was given to study of the strong events (KP ≥ 13.5 and MPSP ≥ 4.7), whose focal solutions reveal the regional stress field.

On generation conditions of strong earthquakes in southern Baikal

In this paper the features of seismic process in the southern depression of Lake Baikal are considered. By the data on focal mechanisms of the earthquakes of February 25, 1999 (Mw = 6.0), and August 27, 2008 (Mw = 6.3), as well as based on configuration of their aftershock fields, it is determined that foci of strong seismic events in southern Baikal are controlled by the greatest structural elements of sublatitudinal and submeridional strikes. It has been shown that a substantial role in the formation of focal zones is played by low-scale destruction of the Earth’s crust, revealed by geological-geophysical data and proved by clustering of seismic shocks. New data on the August 27, 2008, earthquake have proved the high level of seismic danger of this part of the Baikal Rift Zone and allowed us to determine generation conditions of strong earthquakes more precisely.

The 2008 Kultuk earthquake with M w = 6.3 in the south of Baikal: Spatial-temporal analysis of seismic activation

The results of investigating the data of stationary and field observations in the epicentral zone of the Kultuk earthquake of August 27, 2008 with Mw = 6.3 localized south of Baikal are presented. The seismic activation amounting to 1790 aftershocks with Kp ≥ 4 (Mw ≥ 0.9) affected a part of the general fault bounding the southwestern coast of the lake and shallower intrabasin structures. It was established through the cluster analysis that the main shock was located at the periphery of the cloud of the concentrated seismicity component, and three main clusters reflecting a complex character of rupture in the earthquake source were identified in the zone of aftershocks. Owing to a high accuracy of aftershock hypocenters determinations (ERZ ≤ 1.2 km), the local character of the seismisity-generating zones was revealed. Based on the method of mapping seismic regime parameters, it was established that zones of reduced fractionality are recognizable in the central part of the source area; in this case, the entire periphery, except for the southeastern direction (where the main shock epicenter is located), is characterized by a high fractionality, which also points to the complex character of the rupture in the source. On the whole, the aftershock sequence under consideration showed the activation of the southwestern flank of the Southern Baikal region, which remained passive for more than one century, and demonstrated destructive features of the Earth’s crust.

The role of serotonin in the immune system development and functioning during ontogenesis

In this study, we investigated the influence of serotonin on the development and functioning of T- and B-cell-mediated immunity during ontogenesis using the pharmacological model of serotonin depletion in rat fetuses. It has been demonstrated that prenatal serotonin deficiency resulted in a decrease in thymus and spleen weights, changes in their cellular composition, and long-lasting disturbances in cell-mediated and humoral immunity in postnatal ontogenesis. The data obtained suggest that serotonin may be considered a morphogenic factor in development of the immune system.

Recent structures and tectonic regimes of the stress–strain state of the Earth’s crust in the northeastern sector of the Russian Arctic region

A comprehensive investigation aimed at determining seismotectonic types of destruction and the stress–strain state of the Earth’s crust in the main seismogenerating structures of the Arctic–Asian seismic belt is conducted for the territory of the northeastern sector of the Russian Arctic region. Based on the degree of activity of geodynamical processes, the regional principles for ranking neotectonic structures are elaborated, and neotectonic zoning is carried out based on the substantiated differentiation of the corresponding classes. Within the limits of the Laptev Sea, Kharaulakh, and Lena-Anabar segments, we analyzed I the structural–tectonic position of the most recent structures, II the deep structure parameters, III the parameters of the active fault system, and IV the parameters of the tectonic stress field, as revealed from tectonophysical analysis of Late Cenozoic fault and fold deformations. Based on the seismological data, the mean seismotectonic deformation tensors are calculated to determine, in combination with geological and geophysical data, the orientations of the principal stress axes and to reveal the structural–tectonic regularity for tectonic regimes of the stress–strain state of the Earth’s crust in the Arctic sector of the boundary between the Eurasian and North American lithospheric plates.

The brain is one of the most important sources of dopamine in the systemic circulation in the perinatal period of ontogenesis in rats

This study was designed to test the authors’ hypothesis that dopamine passes from dopamine-synthesizing cells in the brain to the systemic circulation prior to the formation of the blood-brain barrier during ontogenesis. High-performance liquid chromatography studies demonstrated that peripheral blood dopamine levels before formation of the blood-brain barrier-in rat fetuses and neonates-are significantly higher than after formation of the barrier in adult rats, providing indirect evidence in support of the hypothesis. Furthermore, formation of the blood-brain barrier is accompanied by a significant increase in dopamine levels in the rat brain. Direct evidence for the hypothesis was obtained in the form of a sharp decrease in blood dopamine levels in fetuses after lesioning of dopamine-synthesizing neurons in the brain by encephalectomy.

Dopamine Synthesis by Non-Dopaminergic Neurons in the Arcuate Nucleus of Rat Fetuses

The aim of the present work was to verify the hypothesis that non-dopaminergic neurons expressing individual complementary dopamine synthesis enzymes can perform the co-located synthesis of dopamine. According to this hypothesis, neurons expressing tyrosine hydroxylase use L-tyrosine for the synthesis of L-dihydroxyphenylalanine (L-DOPA), which then enters neurons expressing aromatic amino acid decarboxylase, which converts L-DOPA to dopamine. Experiments were performed using the mediobasal hypothalamus of rat fetuses, which mostly contains single-enzyme neurons (>99%) and occasional double-enzyme neurons (<1%). Controls were obtained from the fetal substantia nigra, which is enriched with dopaminergic neurons. High-performance liquid chromatography was used to measure levels of dopamine and L-DOPA in cell extracts and the incubation medium after incubation in the presence and absence of exogenous L-tyrosine. Addition of L-tyrosine to the medium led to increases in the level of synthesis and release of L-DOPA in the mediobasal hypothalamus and substantia nigra. In addition, L-tyrosine increased dopamine synthesis in the substantia nigra and decreased dopamine synthesis in the mediobasal hypothalamus. This regional difference in levels of dopamine synthesis is probably due to inhibition of the uptake of L-DOPA from the intercellular medium by neurons in the mediobasal hypothalamus containing aromatic amino acid decarboxylase, due to the competitive binding of the L-DOPA transporter by L-tyrosine. Thus, these results provide the first evidence for the co-located synthesis of dopamine by non-dopaminergic neurons expressing single complementary enzymes involved in the synthesis of this neurotransmitter.

The effect of vasopressin on the Zajdela hepatocellular carcinoma growth rate

222 In mammals, water balance is maintained by a complex neurohormonal system, in which vasoo pressin, a peptide from neurohypophysis that controls reabsorption of water in the tubules, plays the most important role [1]. The impairment of synthesis and secretion of vasopressin leads to pathologically increased excretion of urine with low osmolarity and, as a result, increased water consumption [2]. Brattlee boro rats have an impaired vasopressin expression in the hypothalamus due to deletion of guanine in the coding region leading to the reading frame shift and loss of its single stop codon [3]. Homozygous mutant animals cannot produce the endogenous hormone, so they daily consume and excrete the amount of water equal to 100% of their body weight [4]. The absence of vasopressin in blood causes other functional disorders that are not directly related to water balance control. Significant alterations are found in the immune syss tem [5, 6]. We previously showed that the growth rate of the transplanted Walker 256 carcinosarcoma changed depending on the lack of vasopressin in Bratt tleboro rats. Two after the inoculation of tumor cells, large mature nodules started to reduce down to comm plete disappearance. On the contrary, WAG (Wistar Albino Glaxo) rats with actively expressed vasopressin gene and physiologically normal vasopressin blood level suffered from progressive growth of the tumor, which then caused their death [7].To confirm the putative role of vasopressin in neoplastic processes, we conducted a study in which rats were transplanted with Zajdela ascitic hepatocellular carcinoma with the orii gin and types of tumor cells different from those of the Walker 256 carcinosarcoma. Adult male Brattleboro and WAG rats weiging 260–300 g (7 animals in each group) were used in the study. The rats were obtained from the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences. The rats were kept under the standard conditions with free access to food and water and natural lighting. The study was carried out according to the regulations for handling experii mental animals (the Addendum to the Order of the Ministry of Health no. 755 of August 12, 1977) and international regulations on the protection of animals used for research purposes. Experimental protocols were approved by the Bioethics Committee of the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences. Ascitic tumors are widely used models for in vivo studies and …

Immune proteasomes in the developing rat spleen

Changes in the structure of the rat spleen and the distribution of immune proteasomes in it during early postnatal development have been studied using double immunofluorescent staining of tissue sections with antibodies to the LMP7 immune proteasome subunit and to specific markers of T and B lymphocytes. It has been shown that the white pulp on postnatal day 5 is not yet colonized by lymphocytes and contains a smaller amount of immune proteasomes than the red pulp. At this stage, T and B lymphocytes concentrate mainly in the red pulp. On day 8, B lymphocytes occupy the marginal zone, while T lymphocytes aggregate into dense strands close to the white pulp. By day 18, T lymphocytes form periarteriolar sheaths in the white pulp, and the contents of immune proteasomes in the red and white pulp become equally high. An increase in the total content of immune proteasomes in the spleen on the third postnatal week was revealed in our previous study by Western blotting. In addition to T and B lymphocytes, immune proteasomes have also been revealed in other spleen cell types, probably in macrophages and reticular cells of the white pulp. Thus, the postnatal development of the spleen is associated with an increase in the contents of immune proteasomes in it.