Stereological analysis of the parenchymal and stromal structures of a hypertrophied myocardium in acute arterial hypertension

Arterial hypertension in 35 male Wistar rats was produced by disturbance of the left renal artery circulation. Myocardial tissue reorganization was studied by using the methods of light microscopy and stereological analysis. By the 35th day of the experiment marked alterations of the intramural vessels were found which were manifested in the thickening of the vessel walls due to hyperplasia and hypertrophy of the smooth muscles cells, and in the developing of sclerotic processes in all layers of the arterial walls. At the tissue level a decrease of the volume and surface densities of capillaries and connective tissue cells were determined, that resulted in a decline of the ratio between the volume and surface densities of the structures to the volume density of cardiomyocytes. Informational analysis revealed an increase of entropy and relative entropy of the myocardium tissue during its hypertrophy.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Structural plasticity of synapses in hippocampal slices after oxygen-glucose deprivation

We analyzed structural rearrangements of synaptic contacts in the stratum radiatum of the CA1 area of cultured rat hippocampal slices under conditions of the development of potentiation of synaptic transmission induced by short-term (10 min) oxygen-glucose deprivation (OGD). Studies were carried out using electron microscopy and 3D reconstruction of cellular compartments. Within the 1st h after OGD, we observed increases in the volume of pre-synaptic terminals and post-synaptic spines and also in the area of postsynaptic densities (PSDs) in both asymmetric excitatory and symmetric inhibitory synapses, especially in the case were the PSD was perforated. We also observed significant activation of glial cells (increases in their volume and area of contacts of their processes with the components of synapses). Therefore, OGD results in activationassociated structural rearrangements of both excitatory and inhibitory synapses of the hippocampal CA1 area. Such rearrangements are accompanied by a clearly pronounced reaction of the glia, which correlates with an important role of the latter in modulation of the functioning of neurons.     

Mdm2 promotes genetic instability and transformation independent of p53

Mdm2, a regulator of the tumor suppressor p53, is frequently overexpressed in human malignancies. Mdm2 also has unresolved, p53-independent functions that contribute to tumorigenesis. Here, we show that increased Mdm2 expression induced chromosome/chromatid breaks and delayed DNA double-strand break repair in cells lacking p53 but not in cells with a mutant form of Nbs1, a component of the Mre11/Rad50/Nbs1 DNA repair complex. A 31-amino-acid region of Mdm2 was necessary for binding to Nbs1. Mutation of conserved amino acids in the Nbs1 binding domain of Mdm2 inhibited Mdm2-Nbs1 association and prevented Mdm2 from delaying phosphorylation of H2AX and ATM-S/TQ sites, repair of DNA breaks, and resolution of DNA damage foci. Similarly, the mutation of eight amino acids in the Mdm2 binding domain of Nbs1 inhibited Mdm2-Nbs1 interaction and blocked the ability of Mdm2 to delay DNA break repair. Both Nbs1 and ATM, but not the ubiquitin ligase activity of Mdm2, were necessary to inhibit DNA break repair. Only Mdm2 with an intact Nbs1 binding domain was able to increase the frequency of chromosome/chromatid breaks and the transformation efficiency of cells lacking p53. Therefore, the interaction of Mdm2 with Nbs1 inhibited DNA break repair, leading to chromosome instability and subsequent transformation that was independent of p53.     

Co-Expression of Glutamic Acid Decarboxylase Isoform 67, Membrane Nicotinic Acetylcholine Receptors,and Connexin 36 in Ischemia-Resistant Hippocampal Interneurons

As is known, hippocampal pyramidal neurons are highly sensitive to cerebral ischemia, while some other hippocampal neurons (particularly, interneurons) survive and keep their functional activity under these conditions for a longer time. We studied interneurons of the rat hippocampal organotypic culture after 30-min-long oxygen-glucose deprivation (OGD) using immunohistochemical approaches. Four and 24 h after OGD, the somata of interneurons with no signs of degeneration (revealed by propidium iodide, PI, staining) were immunopositive to antibodies against glutamic acid decarboxylase isoform 67 (GAD67) and to an extracellular domain of a7 nicotinic acetylcholine receptor (nAChR) but negative with respect to choline acetyltransferase (ChAT). GAD67/nAChR-positive interneurons were abundant within all layers of the hippocampal CA1-CA4 zones and also in the dentate gyrus. Co-localized GAD67/nAChR immunopositivity was also observed on numerous punctuate terminals close to the somata of pyramidal neurons stained by PI. After OGD followed by incubation with a blocker of gap junctions, carbenoxolone, only single PI-stained units were revealed in the pyramidal layer. In experiments with connexin 36 cyan fluorescent protein (Cx36-CFP) on gene-reporter mice, we have found that the combination of GAD67/nAChR immunopositivity and ChAT negativity in the hippocampus is specific for the interneuronal somata expressing Cx36-CFP, a component of electrotonic gap contacts in the neuronal networks. Our results indicate that OGD-resistant hippocampal interneurons display co-localization of GAD67, a7 nAChR, and Cx36-CFP. By these neurochemical features, OGD-resistant neurons can be classified as inhibitory GABA-ergic acetylcholine-sensitive interneurons able to couple electrotonically with other hippocampal units through Cx36-CFP-containing gap junctions. The existence of hippocampal interneurons coexpressing the above factors shows that further investigations towards elucidation of cooperative endogenic mechanisms responsible for cerebral neuroresistance are expedient.     

Lipoxygenase inhibitors induce rat hepatocyte apoptosis in primary culture

Arachidonic acid metabolites have been shown to have a wide range of effects on cell proliferation and viability. In this study, the effects of lipoxygenase (LO) inhibitors nordihydroguaiaretic acid (NDGA) and caffeic acid (CA) on the viability of cultured rat hepatocytes (HC) were investigated. As a result, treatment with NDGA and CA for 4 h and 24 h decreased ALT release from HC and increased a number of apoptotic cells. Apoptosis inducing effects of general LO inhibitor NDGA were more pronounced, than those of 5-LO inhibitor CA. The results suggest that lipoxygenase pathway of arachidonic acid metabolism, in particular 5-LO, is essential regulator of hepatocyte survival and apoptosis.     

Comparative cytogenetics of hamsters of the genus Calomyscus

Karyotypes of Calomyscus from different regions of Turkmenistan, Iran, and Azerbaijan were studied using chromosome banding (G- and C-banding) and analyses of meiosis in laboratory hybrids. Extensive variation in the diploid number and the number of autosomal arms (FNa) was revealed (2n = 30, FNa = 44; 2n = 32, FNa = 42; 2n = 44, FNa = 46; 2n = 44, FNa = 58; 2n = 37, FNa = 44; 2n = 50, FNa = 50; 2n = 52, FNa = 56). Centric and tandem fusions and heterochromatin changes were identified as the major modes of karyotype evolution in this group. Natural hybrids between individuals with different karyotypes were recorded, and regular chromosome pairing in meiosis was observed in laboratory hybrids. Fluorescence in situ hybridization with a 353-bp BspRI complex tandem repeat indicated that chromosomal repatterning occurred recently within the genus. There is no unequivocal evidence suggesting the role of chromosomal change in the speciation of the populations of Calomyscus examined.     

A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.