Diffusion modeling system of a neuron's molecular calculating machine

Intracellular injection of cyclic nucleotides through 3-4 barrel microelectrodes usually results in depolarization in case of cyclic AMP and in hyperpolarization in case of cyclic GMP. But sometimes the neuron response is more complex and changes with time. Phosphodiesterase inhibitors, papaverine, 3-isobutyl-1-methylxantine, SQ-20009 increase and prolong the effects of cyclic nucleotides and the complex effect of cyclic GMP is transformed into simple hyperpolarization. Large neurons respond to cyclic AMP with a delay (1-3 sec) after the beginning of iontophoresis. The solution of diffusion equation presents the distance from the microelectrode tip to the point of cyclic AMP action as a function of the delay (100-160 microns). The maximum value of concentration that may be reached at this point after a prolonged injection (10(-5) M) is calculated as well. The system producing and destroying cyclic nucleotides is supposed to be a diffusion analog input of the cell molecular computer. This system can solve various equations of mathematical physics. For this reason guanylatecyclase is supposed to be connected with special biochemical system which realizes harmonic analysis.     

Polymorphisms in glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) in the indigenous and the nonresident population of the Kemerovo region

GSTM1 and GSTT1 gene polymorphisms were studied in Shorians, Teleuts, and Caucasians of the Kemerovo region. It has been shown that distribution of homozygous deletions in the examined groups is significantly heterogeneous. The frequency of deletion genotypes and combinations of deletion in these genes was lower in Shorians and, Teleuts than in Caucasians.     

Generation of rat induced pluripotent stem cells: the analysis of reprogramming and culturing media

The rat represents very important, superior in many respects to the mous, animal model for studying pharmacology, physiology, ageing, cardiovascular etc. However, numerous attempts to derive rat ES cells necessary to carry out loss-of-gene-function studies have not been successful thus far. Therefore rat induct pluripotent stem cells (or riPS) should provide a notable alternative to ES cell, allowing to study gene functions in this valuable animal model. Here we report an improved lentivirus-based riPS derivation protocol that makes use of small inhibitors of MEK and GSK3. We show that the excision of proviruses does not affect neither karyotype and pluripotency state of these cells. Also, we propose genetic tool for an improvement of the quality of riPS cells in culture. These data may prompt further iPS-based gene targeting in rat as well as the development iPS-based gene therapies, using this animal model.     

A bacterial effector counteracts host autophagy by promoting degradation of an autophagy component

Beyond its role in cellular homeostasis, autophagy plays anti‐ and promicrobial roles in host–microbe interactions, both in animals and plants. One prominent role of antimicrobial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate autophagy to escape elimination. Although well‐described in animals, the extent to which xenophagy contributes to plant–bacteria interactions remains unknown. Here, we provide evidence that Xanthomonas campestris pv. vesicatoria (Xcv) suppresses host autophagy by utilizing type‐III effector XopL. XopL interacts with and degrades the autophagy component SH3P2 via its E3 ligase activity to promote infection. Intriguingly, XopL is targeted for degradation by defense‐related selective autophagy mediated by NBR1/Joka2, revealing a complex antagonistic interplay between XopL and the host autophagy machinery. Our results implicate plant antimicrobial autophagy in the depletion of a bacterial virulence factor and unravel an unprecedented pathogen strategy to counteract defense‐related autophagy in plant–bacteria interactions.     

Unusual biochemistry of changes in neuron membrane permeability evoked by cAMP

Influence of different metabolic poisons on cAMP-evoked neuron membrane permeability is investigated. Drugs preventing cAMP binding with R subunits of protein kinase decrease the cAMP-evoked current, but the inhibitor of the C subunit. H8, has no effect. The cAMP-dependent current is increased by uncouplers and decreased by inhibitors of glycolysis and oxidative phosphorylation. The mechanism of cAMP action on neuron permeability is discussed.     

The role of electro-mechanical and reaction-diffusion systems in the intra-neuron processing of information: effect of in-flow of calcium and intracellular calcium on cAMP activity

Influx of calcium ions cannot control a generatory potential induced by the intraneuronal system because calcium ions enter the cell during impulses. These impulses are the result of problem solving and must not influence directly the generatory potential. Therefore cAMP and not calcium controls the permeability of sodium and potassium channels from the inside of the neuron. However the calcium ions and membrane potential of mitochondria affect the impact of cAMP injections. An increase in the intracellular concentration of free Ca2+ induced by the injection of Ca-EGTA buffer with 5.10(-7) M free Ca2+, electric excitation, uncouplers of oxidative phosphorylation or arsenate leads to an increase of cAMP-dependent depolarization and the inward current. The injection of Ca-EGTA buffer with 10(-5) M free Ca2+ and drop in [Ca2+]in by EGTA as well as generation of impulses after cAMP injection decrease the cAMP effect. As rise in [Ca2+]in activates phosphodiesterase and uncouples oxidative phosphorylation, and vanadate in contrast to arsenate suppresses the cAMP effect, a hypothesis is advanced that activating effect of calcium on cAMP action is associated with neuron deenergization.     

Control of receptor internalization, signaling level, and precise arrival at the target in guided cell migration

Activation of the chemokine receptor CXCR4 by SDF1 controls a variety of biological processes in development, immune response, and disease [1-5]. The carboxyl-terminal region of CXCR4 is subject to phosphorylation that allows binding of regulatory proteins [5]; this results in downregulation of CXCR4 signaling and receptor internalization [6]. Notably, truncations of this part of CXCR4 have been implicated in WHIM syndrome, a dominantly inherited immunodeficiency disorder [7, 8]. Despite its importance in receptor signaling and the clinical relevance of its regulation, the precise function of regulating signaling level and internalization in controlling cell behavior is not known. Whereas a number of in vitro studies suggested that the carboxyl terminus of CXCR4 positively regulates chemotaxis (e.g., [9]), others reached the opposite conclusion [8, 10, 11]. These conflicting results highlight the importance of investigating this process under physiological conditions in the live animal. In this study, we demonstrate the significance of internalization and of controlling receptor signaling level for SDF-1-guided migration. We found that whereas internalization and the control over signaling intensity are dispensable for cell motility and directional sensing, they are essential for fine-tuning of migration in vivo, allowing precise arrival of zebrafish PGCs at their target, the region where the gonad develops.