The influence of ethanol on the functional status of GABA(A) receptors

Gamma aminobutyric acid (GABA) is one of the main inhibitory neurotransmitters in the mammalian brain. Its effects are realized via GABA_A, GABA_B, and GABA_C receptors. GABA_A is the most abundant type of GABA receptors. It consists of six classes of subunits, , , , , , and . Acute and chronic exposures to ethanol are accompanied by changes in structure and function of GABA_A receptors. These changes may be a basis for altered behavior seen in alcoholism.     

Changes in localization of cellular vesicular apparatus during differentiation of myoblasts into myotubules in cell culture

A study of changes in intracellular processes in the course of the differentiation of myoblasts into myotubules is of great importance for understanding fundamental problems of cell biology. This primarily concerns the change in the spatial organization of the vacuolar apparatus, which reflects changes in the properties of the membranes, cytoskeleton, and processes of vesicular transport in the course of differentiation. In the present work, the distribution of acid organelles (lysosomes, late endosomes, Golgi cisternae) accumulating acridine orange during the process of the formation of myotubules in the L6J1 cell culture is analyzed. The perinuclear localization of acid cell organelles in myoblasts is shown to be replaced by the diffuse distribution of these organelles throughout the entire volume of the myotubule cytoplasm. The use of lipophilic dyes RH 414 or di-8-ANEPPS enables one to compare the process of formation and dynamics of endocytic vesicles in myoblasts and myotubules. For the analysis of nonspecific endocytosis, we also used the semiconductor nanocrystals, i.e., quantum dots (QDs) conjugated with TAT-peptide, a cell-penetrating peptide. We have shown that the QD-TAT complexes enter into myoblasts via endocytosis. It has been established that QD-TAT complexes penetrate myoblasts, but do not penetrate myotubules, even after incubation for 24 h, which can indicate changes in the properties of the plasma membrane in the process of differentiation of skeletal muscle fibers.     

Acridine orange distribution and fluorescence spectra in myoblasts and single muscle fibers

Acridine orange (AO) fluorescence spectra in nuclei and cytoplasm of living myoblasts L6J1 and frog single muscle fibers have been studied using spectral scanning system of Leica TCS SL confocal microscope. AO fluorescence spectra in salt solutions dependent on free AO concentrations or in complex with DNA have also been obtained. Myoblast nuclei fluoresced in the green spectral region with maximum at about 530 nm; nucleoli had the brightest fluorescence. The fluorescence of nuclear chromatin was not uniform. Similar fluorescence of nuclei and nucleoli was observed in frog single muscle fibers. Uniform, weak, green fluorescence was observed in the myoblast cytoplasm. In the sarcoplasm of muscle fibers, AO green fluorescence was seen in A discs. In the cytoplasm of myoblasts and muscle fibers stained with AO, different red, yellow, and green fluorescent granules, which were acidic organelles, were visualized. The comparison of AO fluorescence spectra in living cells with AO fluorescence spectra in buffer solutions with different AO concentrations and AO in complex with DNA enables the estimation of the AO concentration in acidic granules. It is important for the evaluation of these cellular organelles functions in intracellular transport, adaptation, and apoptosis, as well as in a number of pathological processes.     

Weekly administration of rapamycin improves survival and biomarkers in obese male mice on high‐fat diet

Recent discoveries have revealed the key role of mTOR (target of rapamycin) in aging. Furthermore, rapamycin extends lifespan in mice, especially in female mice. Here, we treated obese male mice on high‐fat diet with rapamycin given intermittently: either weekly (once a week) or alternating bi‐weekly (three injections every other week). While only marginally reducing obesity, intermittent administration of rapamycin significantly extended lifespan. Significance was achieved for weekly treated group and for the three rapamycin‐received groups combined. In weekly treatment group, 100% mice were alive by the age of 2 years, whereas 60% of mice died in untreated group by this age. The effect of weekly treatment on survival was highly significant and cannot be fully explained by partial reduction in obesity. Alternating bi‐weekly treatments seem to be less effective than weekly treatment, although effects of additional factors (see 3 ) may not be excluded. After one year of treatment, all survived mice were sacrificed 8 days after the last administration of rapamycin to avoid its direct interference with parameters examined. Fasting levels of cardiac and hepatic p‐S6, a marker of mTORC1 activity, were lower in weekly treatment group compared with control mice. In contrast, levels of p‐Akt (S473), glucose, triglycerides and insulin were unchanged, whereas leptin and IGF‐1 tended to be lower. Thus, weekly treatment with rapamycin may slow down aging in obese male mice on high‐fat diet.     

Anaerobic Microbial Degradation of Polypropylene and Polyvinyl Chloride Samples

Microbiology - Resistance to biodegradation, which is among the most advantageous features of synthetic polymers, is also the reason for their accumulation in the environment and therefore...     

Untargeted quantum dots in confocal microscopy of living cells

The problem of the nonspecific binding of quantum dots (QDs) with cells is very important, but not fully understood taking into account the possible application of QDs in medical and fundamental studies. The interactions of untargeted CdSe/ZnS QDs with isolated frog muscle fibers, HeLa cells, and J774 cells were investigated. The observations were made on living cells using laser confocal microscopy (Leica TCS SL). QDs covered with polyethylene glycol without any functional reactive groups with an emission maximum at 565 nm were used in the study. This type of QD is suggested to prevent the interaction of QDs with biological molecules. It has been shown that QDs do not enter HeLa cells, the T-system, or the sarcoplasm of skeletal muscle fibers. However, during long-term incubation, J774 cells can take up QDs. The obtained data demonstrated the diversity of interactions of untargeted QDs with different cell types and are important for understanding problems of nonselective uptake and cytotoxicity of QDs.     

Study of Mechanisms of Relaxation in Rat Blood Vessels Differing by Density and Innervation Type

The work deals with a study of physiological significance of relaxation mechanisms initiated by stimulation of -adrenoreceptors and NO-dependent pathways as well as of participation of cyclic nucleotide signal pathways in dilatation of rat blood vessels with different density and type of nervous regulation: of thoracic aorta with poorly developed adrenergic vasoconstrictional innervation, of tail artery with well-developed adrenergic vasoconstrictional innervation, and of portal vein with adrenergic and cholinergic vasoconstrictional innervation. Isometric contraction of 1-mm wide vascular rings produced by electrostimulation or action of exogenous selective antagonists (phenylephrine for ₁-adrenoreceptors of all three vessels and 5-methylformetide for muscarinic cholinergic receptors of portal vein) was recorded using a laboratory-made highly sensitive device. From relaxants, isoproterenol, sodium nitroprusside, forskolin, and isobutylmethylxanthine were used. As a result of the performed study with use of substances affecting various chains of processes providing relaxation of smooth muscle contractile apparatus of blood vessels with different degree of development of nervous regulation, we have obtained data that indicate heterogeneity of intracellular mechanisms of transmission of external signal realizing the contractionndash;relaxation cycle in these vessels.     

S6K in geroconversion

Markers of cellular senescence depend in part on the MTOR (mechanistic target of rapamycin) pathway. MTOR participates in geroconversion, a conversion from reversible cell cycle arrest to irreversible senescence. Recently we demonstrated that hyper-induction of cyclin D1 during geroconversion was mostly dependent on MEK, whereas rapamycin only partially inhibited cyclin D1 accumulation. Here we show that, while not affecting cyclin D1, siRNA for p70S6K partially prevented loss of RP (replicative/regenerative potential) during p21-induced cell cycle arrest. Similarly, an inhibitor of p70 S6 kinase (PF-4708671) partially inhibited phosphorylation of S6 and preserved RP, while only marginally prevented cyclin D1 induction. Thus S6K and MEK play different roles in geroconversion.