Early loss of Xist RNA expression and inactive X chromosome associated chromatin modification in developing primordial germ cells

BACKGROUND: The inactive X chromosome characteristic of female somatic lineages is reactivated during development of the female germ cell lineage. In mouse, analysis of protein products of X-linked genes and/or transgenes located on the X chromosome has indicated that reactivation occurs after primordial germ cells reach the genital ridges. PRINCIPAL FINDINGS/METHODOLOGY: We present evidence that the epigenetic reprogramming of the inactive X-chromosome is initiated earlier than was previously thought, around the time that primordial germ cells (PGCs) migrate through the hindgut. Specifically, we find that Xist RNA expression, the primary signal for establishment of chromosome silencing, is extinguished in migrating PGCs. This is accompanied by displacement of Polycomb-group repressor proteins Eed and Suz(12), and loss of the inactive X associated histone modification, methylation of histone H3 lysine 27. CONCLUSIONS/SIGNIFICANCE: We conclude that X reactivation in primordial germ cells occurs progressively, initiated by extinction of Xist RNA around the time that germ cells migrate through the hindgut to the genital ridges. The events that we observe are reminiscent of X reactivation of the paternal X chromosome in inner cell mass cells of mouse pre-implantation embryos and suggest a unified model in which execution of the pluripotency program represses Xist RNA thereby triggering progressive reversal of epigenetic silencing of the X chromosome.     

Melatonin protects against experimental immune ovarian failure in mice

Experimental immune ovarian failure induced in CBA mice by either administration of xenogenic anti-ovarian antibodies or immunization with allogenic ovarian extracts impaired the meiotic maturation of oocytes and increased apoptosis of follicular cells. Immunization was accompanied with the inflammation and active immune reaction, as shown by the enlargement of regional lymph nodes, the increase of apoptosis in cultured lymph node cells and the increase of band and segmented neutrophil percentage in the blood. Triple injections of melatonin (5 mg/kg of the body weight) an hour before antibodies administration restored the meiotic maturation of oocytes and supported the survival of follicular and lymph node cells. In contrast, melatonin application upon immunization was not effective to prevent the ovary impairment and cell death. It is concluded that melatonin protects against immune ovary failure induced by xenogenic anti-ovarian antibodies.     

Chlorophyll fluorescence induction and relaxation system for the continuous monitoring of photosynthetic capacity in photobioreactors

The development of high‐performance photobioreactors equipped with automatic systems for non‐invasive real‐time monitoring of cultivation conditions and photosynthetic parameters is a challenge in algae biotechnology. Therefore, we developed a chlorophyll (Chl) fluorescence measuring system for the online recording of the light‐induced fluorescence rise and the dark relaxation of the flash‐induced fluorescence yield (Qa^? ? re‐oxidation kinetics) in photobioreactors. This system provides automatic measurements in a broad range of Chl concentrations at high frequency of gas‐tight sampling, and advanced data analysis. The performance of this new technique was tested on the green microalgae Chlamydomonas reinhardtii subjected to a sulfur deficiency stress and to long‐term dark anaerobic conditions. More than thousand fluorescence kinetic curves were recorded and analyzed during aerobic and anaerobic stages of incubation. Lifetime and amplitude values of kinetic components were determined, and their dynamics plotted on heatmaps. Out of these data, stress‐sensitive kinetic parameters were specified. This implemented apparatus can therefore be useful for the continuous real‐time monitoring of algal photosynthesis in photobioreactors.     

CRISPR/Cas9-mediated gfp gene inactivation in Arabidopsis suspension cells

Molecular Biology Reports - Targeted genome editing using CRISPR/Cas9 is a promising technology successfully verified in various plant species; however, it has hardly been used in plant cell...     

Synthetic Oligopeptides Mimicking γ-Core Regions of Cysteine-Rich Peptides of Solanum lycopersicum Possess Antimicrobial Activity against Human and Plant Pathogens

Plant cysteine-rich peptides (CRPs) represent a diverse group of molecules involved in different aspects of plant physiology. Antimicrobial peptides, which directly suppress the growth of pathogens, are regarded as promising templates for the development of next-generation pharmaceuticals and ecologically friendly plant disease control agents. Their oligopeptide fragments are even more promising because of their low production costs. The goal of this work was to explore the antimicrobial activity of nine short peptides derived from the γ-core-containing regions of tomato CRPs against important plant and human pathogens. We discovered antimicrobial activity in peptides derived from the defensin-like peptides, snakins, and MEG, which demonstrates the direct involvement of these CRPs in defense reactions in tomato. The CRP-derived short peptides appeared particularly active against the gram-positive bacterium Clavibacter michiganensis, which causes bacterial wilt—opening up new possibilities for their use in agriculture to control this dangerous disease. Furthermore, high inhibitory potency of short oligopeptides was demonstrated against the yeast Cryptococcus neoformans, which causes serious diseases in humans, making these peptide molecules promising candidates for the development of next-generation pharmaceuticals. Studies of the mode of action of the two most active peptides indicate fungal membrane permeabilization as a mechanism of antimicrobial action.     

RhoA interaction with inositol 1,4,5-trisphosphate receptor and transient receptor potential channel-1 regulates Ca2+ entry. Role in signaling increased endothelial permeability

We tested the hypothesis that RhoA, a monomeric GTP-binding protein, induces association of inositol trisphosphate receptor (IP3R) with transient receptor potential channel (TRPC1), and thereby activates store depletion-induced Ca2+ entry in endothelial cells. We showed that RhoA upon activation with thrombin associated with both IP3R and TRPC1. Thrombin also induced translocation of a complex consisting of Rho, IP3R, and TRPC1 to the plasma membrane. IP3R and TRPC1 translocation and association required Rho activation because the response was not seen in C3 transferase (C3)-treated cells. Rho function inhibition using Rho dominant-negative mutant or C3 dampened Ca2+ entry regardless of whether Ca2+ stores were emptied by thrombin, thapsigargin, or inositol trisphosphate. Rho-induced association of IP3R with TRPC1 was dependent on actin filament polymerization because latrunculin (which inhibits actin polymerization) prevented both the association and Ca2+ entry. We also showed that thrombin produced a sustained Rho-dependent increase in cytosolic Ca2+ concentration [Ca2+]i in endothelial cells overexpressing TRPC1. We further showed that Rho-activated Ca2+ entry via TRPC1 is important in the mechanism of the thrombin-induced increase in endothelial permeability. In summary, Rho activation signals interaction of IP3R with TRPC1 at the plasma membrane of endothelial cells, and triggers Ca2+ entry following store depletion and the resultant increase in endothelial permeability.     

Comparison of the aerobic performance of leg and arm muscles in cross-country skiers

In the last fifteen years, a trend has appeared in cross-country ski racing to increase the use of double poling and, therefore, to increase the load on the shoulder girdle (arm) muscles. The purpose of this study was to compare the aerobic performance of elite cross-country skiers in incremental running (treadmill) and double poling (with manual ski ergometer) tests to exhaustion. Four junior cross-country skiers and four biathletes ( $ \dot V_{O_{2max} } $ = 70 (66?C72) mL/min per kg body weight) participated in the experiment. In the double poling test, the lactate concentration increased more rapidly than in the running test, and the peak oxygen consumption ( $ \dot V_{O_{2peak} } $ ) in the double poling test was 88 (84?C93)% of the maximal oxygen consumption ( $ \dot V_{O_{2max} } $ ) in the running test. The relative anaerobic threshold, which characterizes the relative level of current aerobic performance, in the double poling test was significantly lower than in the running test (79 (57?C83)% vs 94 (90?C98)%, respectively). On the basis of these data, it can be concluded that the main reserve for a further increase in the aerobic performance of cross-country skiers and biathletes is the increase in the aerobic capacity of arm and trunk muscles.     

Sensory characteristics of the cortical input to the hippocampus: the entorhinal cortex]

Sensory reactions of neurones in the medial entorhinal area were investigated in unanaesthetized rabbits. 54% of the units were multimodal. Different stimuli evoked various response patterns with complex on-off components. Differential coding of pure tones was observed in many cells, which were also sensitive to other sensory modalities. Complete habituation of responses was virtually absent; only partial reduction of the late components was observed in some cases. In 71% of units reactions were stable or incremental (gradual development and increase). It may be concluded that from the entorhinal cortex the hippocampus receives highly differentiated signals of "associative" type, which do not habituate and are of a stable or incremental nature.     

Effect of redox potential on activity of hydrogenase 1 and hydrogenase 2 in Escherichia coli

This report elucidates the distinctions of redox properties between two uptake hydrogenases in Escherichia coli. Hydrogen uptake in the presence of mediators with different redox potential was studied in cell-free extracts of E. coli mutants HDK103 and HDK203 synthesizing hydrogenase 2 or hydrogenase 1, respectively. Both hydrogenases mediated H(2) uptake in the presence of high-potential acceptors (ferricyanide and phenazine methosulfate). H(2) uptake in the presence of low-potential acceptors (methyl and benzyl viologen) was mediated mainly by hydrogenase 2. To explore the dependence of hydrogen consumption on redox potential of media in cell-free extracts, a chamber with hydrogen and redox ( E(h)) electrodes was used. The mutants HDK103 and HDK203 exhibited significant distinctions in their redox behavior. During the redox titration, maximal hydrogenase 2 activity was observed at the E(h) below -80 mV. Hydrogenase 1 had maximum activity in the E(h) range from +30 mV to +110 mV. Unlike hydrogenase 2, the activated hydrogenase 1 retained activity after a fast shift of redox potential up to +500 mV by ferricyanide titration and was more tolerant to O(2). Thus, two hydrogenases in E. coli are complementary in their redox properties, hydrogenase 1 functioning at higher redox potentials and/or at higher O(2) concentrations than hydrogenase 2.