Tcf15 Primes Pluripotent Cells for Differentiation

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Highlights? Tcf15 marks a subpopulation of pluripotent cells primed for somatic lineages ? Tcf15 expression is regulated by FGF signaling ? Tcf15 activity is repressed by Id proteins ? Tcf15 represses Nanog and drives differentiation once released from Id inhibition     

Calibration of mammalian skeletal muscle Ca2+ transients recorded with the fast Ca2+ dye Mag-Fluo-4

BackgroundMag-Fluo-4 is increasingly employed for studying Ca²⁺ signaling in skeletal muscle; however, the lack of information on the Ca²⁺-Mag-Fluo-4 reaction limits its wider usage.MethodsFluorescence and isothermal titration calorimetry (ITC) experiments were performed to determine the binding stoichiometry (n) and thermodynamics (enthalpy (ΔH) and entropy (ΔS) changes), as well as the in vitro and in situ K_d of the Ca²⁺-Mag-Fluo-4 reaction. Rate constants (k_on, k_off), fluorescence maximum (F_max), minimum (F_min), and the dye compartmentalization were also estimated. Experiments in cells used enzymatically dissociated flexor digitorum brevis fibres of C57BL6, adult mice, loaded at room temperature for 8 min, with 6 μM Mag-Fluo-4, AM, and permeabilized with saponin or ionomycin. All measurements were done at 20 °C.ResultsThe in vitro fluorescence assays showed a binding stoichiometry of 0.5 for the Ca²⁺/Mag-Fluo-4 (n = 5) reaction. ITC results (n = 3) provided ΔH and ΔS values of 2.3 (0.7) kJ/mol and 97.8 (5.9) J/mol.K, respectively. The in situ K_d was 1.652 × 10⁵μM²(n = 58 fibres, R² = 0.99). With an F_max of 150.9 (8.8) A.U. (n = 8), F_min of 0.14 (0.1) A.U. (n = 10), and ΔF of Ca²⁺ transients of 8.4 (2.5) A.U. (n = 10), the sarcoplasmic [Ca²⁺]_peak reached 22.5 (7.8) μM. Compartmentalized dye amounted to only 1.1 (0.7)% (n = 10).CONCLUSIONS: Two Mag-Fluo-4 molecules coalesce around one Ca²⁺ ion, in an entropy-driven, very low in situ affinity reaction, making it suitable to reliably track the kinetics of rapid muscle Ca²⁺ transients.General significanceOur results may be relevant to the quantitative study of Ca²⁺ kinetics in many other cell types.     

Complex-dependent histone acetyltransferase activity of KAT8 determines its role in transcription and cellular homeostasis

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IFIT1 Differentially Interferes with Translation and Replication of Alphavirus Genomes and Promotes Induction of Type I Interferon

Alphaviruses are a group of widely distributed human and animal pathogens. It is well established that their replication is sensitive to type I IFN treatment, but the mechanism of IFN inhibitory function remains poorly understood. Using a new experimental system, we demonstrate that in the presence of IFN-β, activation of interferon-stimulated genes (ISGs) does not interfere with either attachment of alphavirus virions to the cells, or their entry and nucleocapsid disassembly. However, it strongly affects translation of the virion-delivered virus-specific RNAs. One of the ISG products, IFIT1 protein, plays a major role in this translation block, although an IFIT1-independent mechanism is also involved. The 5’UTRs of the alphavirus genomes were found to differ significantly in their ability to drive translation in the presence of increased concentration of IFIT1. Prior studies have shown that adaptation of naturally circulating alphaviruses to replication in tissue culture results in accumulation of mutations in the 5’UTR, which increase the efficiency of the promoter located in the 5’end of the genome. Here, we show that these mutations also decrease resistance of viral RNA to IFIT1-induced translation inhibition. In the presence of higher levels of IFIT1, alphaviruses with wt 5’UTRs became potent inducers of type I IFN, suggesting a new mechanism of type I IFN induction. We applied this knowledge of IFIT1 interaction with alphaviruses to develop new attenuated variants of Venezuelan equine encephalitis and chikungunya viruses that are more sensitive to the antiviral effects of IFIT1, and thus could serve as novel vaccine candidates.     

Use of cultivated plants and non-plant remedies for human and animal home-medication in Liubań district,Belarus

Background

To use any domestic remedy, specific knowledge and skills are required. Simple logic dictates that the use of wild plants in the context of limited interaction with nature requires prior identification, while in the case of non-plant remedies and cultivated plants this step can be omitted. This paper aims to document the current and past uses of non-plant remedies and cultivated plants in the study region for human/animal medication; to analyze the human medicinal and veterinary use areas in the context of the remedy groups; to qualitatively compare the results with relevant historical publications; and to compare the intensity and purpose of use between the remedy groups.

Methods

During field studies 134 semi-structured interviews were conducted with locals from 11 villages in the Liubań district of Belarus. Currently used home-remedies as well as those used in the past were documented by employing the folk history method. The subject was approached through health-related uses, not by way of remedies. Interview records were digitalized and structured in Detailed Use Records in order to ascertain local perceptions. An Informant Consensus Factor (FIC) was calculated for remedy groups as well as for different use categories.

Results

In the human medication area the use of nearby remedies was neither very diverse nor numerous: 266 DUR for 45 taxa belonging to 27 families were recorded for cultivated plants along with 188 DUR for 58 different non-plant remedies. The FIC values for both remedy groups were lower than for wild plants. In the ethnoveterinary medicine use area there were 48 DUR referring to the use of 14 cultivated plant taxa from 12 families and 72 DUR referring to the use of 31 non-plant remedies. The FIC value for the whole veterinary use area of cultivated plants was relatively low, yet similar to the FIC of wild plants.

Conclusions

Differences between remedy groups were pronounced, indicating that in domestic human medicine cultivated plants and non-plant remedies are either remarkably less important than wild ones or not considered worth talking about. In ethnoveterinary medicine non-plant remedies are almost equally important as wild plants, while cultivated plants are the least used. People in study area seem to still more often rely on, or are more willing to talk to strangers about, wild plants, as promoted by both official medicine and popular literature.