Single-ion-conducting polymers are ideal electrolytes for rechargeable lithium batteries as they eliminate salt concentration gradients and concomitant concentration overpotentials during battery ...cycling. Here we study the ionic conductivity and morphology of poly(ethylene oxide)-b-poly(styrenesulfonyllithium(trifluoromethylsulfonyl)imide) (PEO-b-PSLiTFSI) block copolymers with no added salt using ac impedance spectroscopy and small-angle X-ray scattering. The PEO molecular weight was held fixed at 5.0 kg mol–1, and that of PSLiTFSI was varied from 2.0 to 7.5 kg mol–1. The lithium ion concentration and block copolymer composition are intimately coupled in this system. At low temperatures, copolymers with PSLiTFSI block molecular weights ≤4.0 kg mol–1 exhibited microphase separation with crystalline PEO-rich microphases and lithium ions trapped in the form of ionic clusters in the glassy PSLiTFSI-rich microphases. At temperatures above the melting temperature of the PEO microphase, the lithium ions were released from the clusters, and a homogeneous disordered morphology was obtained. The ionic conductivity increased abruptly by several orders of magnitude at this transition. Block copolymers with PSLiTFSI block molecular weights ≥5.4 kg mol–1 were disordered at all temperatures, and the ionic conductivity was a smooth function of temperature. The transference numbers of these copolymers varied from 0.87 to 0.99. The relationship between ion transport and molecular structure in single-ion-conducting block copolymer electrolytes is qualitatively different from the well-studied case of block copolymers with added salt.
The immune response against transplanted allografts is one of the most potent reactions mounted by the immune system. The acute rejection response has been attributed to donor dendritic cells (DCs), ...which migrate to recipient lymphoid tissues and directly activate alloreactive T cells against donor MHC molecules. Here, using a murine heart transplant model, we determined that only a small number of donor DCs reach lymphoid tissues and investigated how this limited population of donor DCs efficiently initiates the alloreactive T cell response that causes acute rejection. In our mouse model, efficient passage of donor MHC molecules to recipient conventional DCs (cDCs) was dependent on the transfer of extracellular vesicles (EVs) from donor DCs that migrated from the graft to lymphoid tissues. These EVs shared characteristics with exosomes and were internalized or remained attached to the recipient cDCs. Recipient cDCs that acquired exosomes became activated and triggered full activation of alloreactive T cells. Depletion of recipient cDCs after cardiac transplantation drastically decreased presentation of donor MHC molecules to directly alloreactive T cells and delayed graft rejection in mice. These findings support a key role for transfer of donor EVs in the generation of allograft-targeting immune responses and suggest that interrupting this process has potential to dampen the immune response to allografts.
The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this ...process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA—directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations.
Hexokinases (HXKs) and fructokinases (FRKs) are the only two families of enzymes in plants that have been identified as able to phosphorylate Glucose (Glc) and Fructose (Fru). Glc can only be ...phosphorylated in plants by HXKs, while Fru can be phosphorylated by either HXKs or FRKs. The various subcellular localizations of HXKs in plants indicate that they are involved in diverse functions, including anther dehiscence and pollen germination, stomatal closure in response to sugar levels, stomatal aperture and reducing transpiration. Its association with modulating programmed cell death, and responses to oxidative stress and pathogen infection (abiotic and biotic stresses) also have been reported. To extend our understanding about the function of HXK-like genes in the response of Prunus rootstocks to abiotic stress, we performed a detailed bioinformatic and functional analysis of hexokinase 3-like genes (HXK3s) from two Prunus rootstock genotypes, 'M.2624' (Prunus cerasifera Ehrh × P. munsoniana W.Wight & Hedrick) and 'M.F12/1' (P. avium L.), which are tolerant and sensitive to hypoxia stress, respectively. A previous large-scale transcriptome sequencing of roots of these rootstocks, showed that this HXK3-like gene that was highly induced in the tolerant genotype under hypoxia conditions. In silico analysis of gene promoters from M.2624 and M.F12/1 genotypes revealed regulatory elements that could explain differential transcriptional profiles of HXK3 genes. Subcellular localization was determinates by both bioinformatic prediction and expression of their protein fused to the green fluorescent protein (GFP) in protoplasts and transgenic plants of Arabidopsis. Both approaches showed that they are expressed in plastids. Metabolomics analysis of Arabidopsis plants ectopically expressing Prunus HXK3 genes revealed that content of several metabolites including phosphorylated sugars (G6P), starch and some metabolites associated with the TCA cycle were affected. These transgenic Arabidopsis plants showed improved tolerance to salt and drought stress under growth chamber conditions. Our results suggest that Prunus HXK3 is a potential candidate for enhancing tolerance to salt and drought stresses in stone fruit trees and other plants.
Animals’ facial expressions are widely used as a readout for emotion. Scientific interest in the facial expressions of laboratory animals has centered primarily on negative experiences, such as pain, ...experienced as a result of scientific research procedures. Recent attempts to standardize evaluation of facial expressions associated with pain in laboratory animals has culminated in the development of “grimace scales”. The prevention or relief of pain in laboratory animals is a fundamental requirement for in vivo research to satisfy community expectations. However, to date it appears that the grimace scales have not seen widespread implementation as clinical pain assessment techniques in biomedical research. In this review, we discuss some of the barriers to implementation of the scales in clinical laboratory animal medicine, progress made in automation of collection, and suggest avenues for future research.
Background Efficient development of atopic diseases requires interactions between allergen and adjuvant to initiate and amplify the underlying inflammatory responses. Substance P (SP) and hemokinin-1 ...(HK-1) are neuropeptides that signal through the neurokinin-1 receptor (NK1R) to promote inflammation. Mast cells initiate the symptoms and tissue effects of atopic disorders, secreting TNF and IL-6 after FcεRI cross-linking by antigen-IgE complexes (FcεRI-activated mast cells FcεRI-MCs). Additionally, MCs express the NK1R, suggesting an adjuvant role for NK1R agonists in FcεRI-MC–mediated pathologies; however, in-depth research addressing this relevant aspect of MC biology is lacking. Objective We sought to investigate the effect of NK1R signaling and the individual roles of SP and HK-1 as potential adjuvants for FcεRI-MC–mediated allergic disorders. Methods Bone marrow–derived mast cells (BMMCs) from C57BL/6 wild-type (WT) or NK1R−/− mice were used to investigate the effects of NK1R signaling on FcεRI-MCs. BMMCs generated from Tac1−/− mice or after culture with Tac4 small interfering RNA were used to address the adjuvancy of SP and HK-1. WT, NK1R−/− , and c-Kit W-sh/W-sh mice reconstituted with WT or NK1R−/− BMMCs were used to evaluate NK1R signaling on FcεRI-MC–mediated passive local and systemic anaphylaxis and on airway inflammation. Results FcεRI-activated MCs upregulated NK1R and HK-1 transcripts and protein synthesis, without modifying SP expression. In a positive signaling loop HK-1 promoted TNF and IL-6 secretion by MC degranulation and protein synthesis, the latter through the phosphoinositide 3-kinase/Akt/nuclear factor κB pathways. In vivo NK1R signaling was necessary for the development of passive local and systemic anaphylaxis and airway inflammation. Conclusions FcεRI stimulation of MCs promotes autocrine secretion of HK-1, which signals through NK1R to provide adjuvancy for efficient development of FcεRI-MC–mediated disorders.
Background
Bone demineralization has shown to be advantageous in autogenous onlay bone grafts and in pre‐osteoblasts cultures, but such procedure has never been evaluated in particulate bone grafts. ...This study aimed to investigate the role of two demineralizing agents in the repair of the 8‐mm critical‐size defects in rats’ calvaria.
Methods
Eighty adult male Wistar rats were randomly assigned to one of eight groups as follows: particulate autogenous bone demineralized with citric acid for 15 seconds (CA15), 30 seconds (CA30), or 60 seconds (CA60); particulate autogenous bone demineralized with tetracycline hydrochloride for 15 seconds (TCN15), 30 seconds (TCN30), or 60 seconds (TCN60); blood clot (NC), and non‐demineralized autogenous bone (PC). The calvariae were harvested at 30 and 60 postoperative days (n = 5) for blinded histological and histometric analysis of the percentage area of newly formed bone within the defects.
Results
In the NC and TCN groups, bone formation was limited to the margins of the defects at 30 postoperative days, whereas complete closure was present in all the specimens from CA15 group. Both at 30 and 60 postoperative days, histomorphometry showed significant higher area of newly formed bone in specimens demineralized with CA than in those demineralized with TCN or non‐demineralized (P < 0.05). TCN appeared to impair bone neoformation, as its use produced similar or inferior results compared to blood clot.
Conclusions
Demineralization of particulate bone grafts with CA during 15s enhanced the regeneration of critical‐size defects and may be a promising adjuvant in regenerative procedures. TCN seems to be improper for this purpose.
Background
Screening for pulmonary hypertension (PHT) is recommended in children with sickle cell disease (SCD). However, best approaches are poorly described. We examined the utility of PHT ...symptoms, echocardiogram (ECHO), N‐terminal‐pro hormone brain natriuretic peptide (NT‐proBNP), and BNP to screen for PHT in the SCD pediatric population.
Methods
Children (8–18 years old) with SCD‐HbSS and HbSthal° were prospectively included and underwent PHT screening. The screening consisted of a comprehensive PHT symptoms evaluation, ECHO measurement, and NT‐proBNP and BNP levels.
Results
A total of 73 patients were included (mean age 12 ± 5.7 years; >80% on hydroxyurea), of which 37% had a symptom consistent with PHT, including exertional dyspnea (26.5%), fatigue (17.6%), palpitation (14.7%), and chest pain (10.3%). ECHO was obtained in 53 (72.6%) patients, with only ECHO of 48 patients included in the final analysis. Elevated ECHO peak tricuspid regurgitant jet velocity (TRV) >2.5 m/s or indirect findings to suggest PHT were seen in only two of 48 (4.2%). No significant differences were seen between those with and without PHT symptoms when compared for NT‐proBNP, BNP, hemoglobin, pulmonary function testing, fractional exhaled nitric oxide, asthma, oxygen saturation, and sleep apnea.
Conclusion
PHT symptoms are not consistent with ECHO, NT‐proBNP nor BNP findings in children with SCD. PHT prevalence based on TRV was low in children on hydroxyurea, therefore screening may not be warranted for this group.
Efficient Ca2+ flux induced during cognate T cell activation requires signaling the T cell receptor (TCR) and unidentified G-protein-coupled receptors (GPCRs). T cells express the neurokinin-1 ...receptor (NK1R), a GPCR that mediates Ca2+ flux in excitable and non-excitable cells. However, the role of the NK1R in TCR signaling remains unknown. We show that the NK1R and its agonists, the neuropeptides substance P and hemokinin-1, co-localize within the immune synapse during cognate activation of T cells. Simultaneous TCR and NK1R stimulation is necessary for efficient Ca2+ flux and Ca2+-dependent signaling that sustains the survival of activated T cells and helper 1 (Th1) and Th17 bias. In a model of contact dermatitis, mice with T cells deficient in NK1R or its agonists exhibit impaired cellular immunity, due to high mortality of activated T cells. We demonstrate an effect of the NK1R in T cells that is relevant for immunotherapies based on pro-inflammatory neuropeptides and its receptors.
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•T cells express the neurokinin 1 receptor (NK1R) and synthesize its agonists•The NK1R and its agonists co-localize in or near the T cell: APC immune synapse•The NK1R promotes optimal Ca2+ flux and survival of TCR-activated T cells•Lack of the NK1R or its agonists results in deficient Th1-/Th17-biased immunity
The neurokinin 1 receptor (NK1R) induces Ca2+ flux in excitable cells. Here, Morelli et al. show that NK1R signaling in T cells promotes optimal Ca2+ flux triggered by TCR stimulation, which is necessary to sustain T cell survival and the efficient Th1- and Th17-based immunity that is relevant for immunotherapies based on pro-inflammatory neuropeptides.
Transcription factor Runx2 controls bone development and osteoblast differentiation by regulating expression of a significant number of bone-related target genes. Here, we report that transcriptional ...activation and repression of the Runx2 gene via its osteoblast-specific P1 promoter (encoding mRNA for the Runx2/p57 isoform) is accompanied by selective deposition and elimination of histone marks during differentiation of mesenchymal cells to the osteogenic and myoblastic lineages. These epigenetic profiles are mediated by key components of the Trithorax/COMPASS-like and Polycomb group complexes together with histone arginine methylases like PRMT5 and lysine demethylases like JARID1B/KDM5B. Importantly, knockdown of the H3K4me2/3 demethylase JARID1B, but not of the demethylases UTX and NO66, prevents repression of the Runx2 P1 promoter during myogenic differentiation of mesenchymal cells. The epigenetically forced expression of Runx2/p57 and osteocalcin, a classical bone-related target gene, under myoblastic-differentiation is accompanied by enrichment of the H3K4me3 and H3K27ac marks at the Runx2 P1 promoter region. Our results identify JARID1B as a key component of a potent epigenetic switch that controls mesenchymal cell fate into myogenic and osteogenic lineages.
Background: Runx2 is the master regulator of osteoblast differentiation.
Results: JARID1B/KDM5B is a key component of the epigenetic mechanisms that control Runx2 expression during osteoblast and myoblast differentiation. These mechanisms operate at the P1 promoter.
Conclusion: Epigenetic mechanisms regulate Runx2 expression and osteoblast-lineage commitment.
Significance: The work provides new mechanistic insights of Runx2 gene expression control during mesenchymal fate determination.
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