Stereological ultrastructural study of myocardial atrophy in hypokinesia

The myocardium of Wistar rats immobilized for 5, 15 and 30 days was examined by morphometry and stereological methods for evaluating the volumetric and surface density of myofibrils, mitochondria, T system, sarcoplasmic reticulum and for the measurement of the volumetric ratio of different ultrastructures to the density of myofibrils and the surface-volumetric ratio of the main organelles of the cardiomyocyte. Myocardial atrophy was shown to develop in the course of hypokinesia. The 30-day hypokinesia entailed changes in ultrastructural organization of cardiomyocytes, attesting to the tension of intracellular systems responsible for energy supply, of ionic membrane transport and the contractile apparatus.     

Molecular mechanisms underlying oxygen reception

In this review, modern concepts on molecular mechanisms underlying reception of the oxygen level in natural O₂-sensory structures and cellular in vitro models are considered and discussed.Neirofiziologiya/Neurophysiology, Vol.36, No.4, pp.330–347, July–August, 2004.     

Effect of dose magnitude and fractionation on the radiation damage to bone marrow cells forming granulocyte-macrophage colonies in diffusion chambers

The ability of CFUdc to repair radiation-induced lesions in the irradiated body was studied by the methods of dose fractionation and dose-rate reduction. With the dose-rate decreased from 1-0.5 Gy/min to 0.02 Gy/min, a mean lethal dose per cell increased from 1.35 up to 1.93 Gy. With fractionation of the dose, the known picture of repair of sublethal radiation lesions was obtained the second survival peak being insignificant. The authors discuss the possible causes of the distinctions in the repair parameters of CFUdc obtained by the two methods.     

Late Replication Domains Are Evolutionary Conserved in the Drosophila Genome

Drosophila chromosomes are organized into distinct domains differing in their predominant chromatin composition, replication timing and evolutionary conservation. We show on a genome-wide level that genes whose order has remained unaltered across 9 Drosophila species display late replication timing and frequently map to the regions of repressive chromatin. This observation is consistent with the existence of extensive domains of repressive chromatin that replicate extremely late and have conserved gene order in the Drosophila genome. We suggest that such repressive chromatin domains correspond to a handful of regions that complete replication at the very end of S phase. We further demonstrate that the order of genes in these regions is rarely altered in evolution. Substantial proportion of such regions significantly coincide with large synteny blocks. This indicates that there are evolutionary mechanisms maintaining the integrity of these late-replicating chromatin domains. The synteny blocks corresponding to the extremely late-replicating regions in the D. melanogaster genome consistently display two-fold lower gene density across different Drosophila species.     

Quantitative interrelationship between the parenchyma and the stroma of the rabbit myocardium in atherosclerotic cardiosclerosis]

The relative volume of myocardial fibers, connective tissue cells, capillaries, interstitial space and surface area of the myocardial fibers and capillaries per tissue volume unit of the myocardium were measured during diffuse cardiosclerosis under conditions of experimental atherosclerosis. A significant decrease in the relative volume of the myocardial fibers alone with a concomitant increase of the extracellular space of the stroma were demonstrated.     

Interaction with Tsg101 Is Necessary for the Efficient Transport and Release of Nucleocapsids in Marburg Virus-Infected Cells

Endosomal sorting complex required for transport (ESCRT) machinery supports the efficient budding of Marburg virus (MARV) and many other enveloped viruses. Interaction between components of the ESCRT machinery and viral proteins is predominantly mediated by short tetrapeptide motifs, known as late domains. MARV contains late domain motifs in the matrix protein VP40 and in the genome-encapsidating nucleoprotein (NP). The PSAP late domain motif of NP recruits the ESCRT-I protein tumor susceptibility gene 101 (Tsg101). Here, we generated a recombinant MARV encoding NP with a mutated PSAP late domain (rMARV_PSAPmut). rMARV_PSAPmut was attenuated by up to one log compared with recombinant wild-type MARV (rMARV_wt), formed smaller plaques and exhibited delayed virus release. Nucleocapsids in rMARV_PSAPmut-infected cells were more densely packed inside viral inclusions and more abundant in the cytoplasm than in rMARV_wt-infected cells. A similar phenotype was detected when MARV-infected cells were depleted of Tsg101. Live-cell imaging analyses revealed that Tsg101 accumulated in inclusions of rMARV_wt-infected cells and was co-transported together with nucleocapsids. In contrast, rMARV_PSAPmut nucleocapsids did not display co-localization with Tsg101, had significantly shorter transport trajectories, and migration close to the plasma membrane was severely impaired, resulting in reduced recruitment into filopodia, the major budding sites of MARV. We further show that the Tsg101 interacting protein IQGAP1, an actin cytoskeleton regulator, was recruited into inclusions and to individual nucleocapsids together with Tsg101. Moreover, IQGAP1 was detected in a contrail-like structure at the rear end of migrating nucleocapsids. Down regulation of IQGAP1 impaired release of MARV. These results indicate that the PSAP motif in NP, which enables binding to Tsg101, is important for the efficient actin-dependent transport of nucleocapsids to the sites of budding. Thus, the interaction between NP and Tsg101 supports several steps of MARV assembly before virus fission.     

Morphofunctional State of Epiphysis in Relatively Wild and Domesticated Silver-Black Foxes during Pregnancy

Morphological indices of changes in the epiphysis activity during pregnancy are analyzed in relatively wild and domesticated silver-black foxes. The diameter of light actively functioning nuclei of pinealocytes increased most significantly and reliably in the end of pregnancy and, at the same time, the area of their surface decreased. These signs witness an enhanced protein synthesis. Unlike other stages of ontogenesis, the degree and dynamics of epiphysis activity during the period of pregnancy were similar in animals of both groups.     

Ethnic Peculiarities of the Lipid Profile in Adolescent Representatives of Some Indigenous Ethnic Groups of Siberia

The indicators of lipid metabolism were analyzed comparatively in 258 adolescent girls and boys representing major ethnic groups of Eastern Siberia: indigenous Tofalars, Evenks and Buryats and alien Europoids (Caucasoids). The adolescent lipid profile in these groups was found to be ethnos-specific. In contemporary Tofalars and Buryats, its indicators are stable, while the overall lipid profile shows an anti-atherogenic trend. By contrast, Evenks and Europoids show an increasing level of cholesterol-containing blood components.