Interlinking interleukin-7

The signaling processes that maintain the homeostatic proliferation of peripheral T-cells and result in their self-renewal largely remain to be elucidated. Much focus has been placed on the anti-apoptotic function of the cytokine, interleukin-7 (IL-7), during T-cell development. But a more critical role has been ascribed to IL-7 as a mediator of peripheral T-cell maintenance. The biological effects responsive to IL-7 signaling are transduced through only a few well-known pathways. In this review we will focus on the signals transduced by IL-7 and similar cytokines, examining how proliferative signals originate from cytokine receptors, are amplified and eventually alter gene expression. In this regard we will highlight the crosstalk between pathways that promote survival, drive cell cycle progression and most importantly provide the needed energy to sustain these critical cellular activities. Though this review showcases much of what has been learned about IL-7 proliferative signaling, it also reveals the significant gaps in our knowledge about cytokine signaling in the very relevant context of peripheral T-cell homeostasis.     

Substrate specificities and electron paramagnetic resonance properties of benzylsuccinate synthases in anaerobic toluene and<Emphasis Type="Italic"> m</Emphasis>-xylene metabolism

The anaerobic degradation pathways of toluene and m-xylene are initiated by addition of a fumarate cosubstrate to the methyl group of the hydrocarbon, yielding (R)-benzylsuccinate and (3-methylbenzyl)succinate, respectively, as first intermediates. These reactions are catalyzed by a novel glycyl-radical enzyme, (R)-benzylsuccinate synthase. Substrate specificities of benzylsuccinate synthases were analyzed in Azoarcus sp. strain T and Thauera aromatica strain K172. The enzyme of Azoarcus sp. strain T converts toluene, but also all xylene and cresol isomers, to the corresponding succinate adducts, whereas the enzyme of T. aromatica is active with toluene and all cresols, but not with any xylene isomer. This corresponds to the capabilities of Azoarcus sp. strain T to grow on either toluene or m-xylene, and of T. aromatica to grow on toluene as sole hydrocarbon substrate. Thus, differences in the substrate spectra of the respective benzylsuccinate synthases of the two strains contribute to utilization of different aromatic hydrocarbons, although growth on different substrates also depends on additional determinants. We also provide direct evidence by electron paramagnetic resonance (EPR) spectroscopy that glycyl radical enzymes corresponding to substrate-induced benzylsuccinate synthases are specifically detectable in anoxically prepared extracts of toluene- or m-xylene-grown cells. The presence of the EPR signals and the determined amount of the radical are consistent with the respective benzylsuccinate synthase activities. The properties of the EPR signals are highly similar to those of the prototype glycyl radical enzyme pyruvate formate lyase, but differ slightly from previously reported parameters for partially purified benzylsuccinate synthase.     

烟草可培养内生细菌的分离及多样性分析

采用稀释平板法, 从健康烟草的根、茎、叶组织中分离到267株内生细菌。利用细菌菌落表征性状和16S rRNA序列对这些分离物进行了多样性分析。通过数值分析比较了8个菌落形态表征性状, 以类平均连锁聚类法的方式进行聚类分析, 在2.15的水平上可分成5个聚类群和56个亚群。16S rDNA序列系统发育分析表明267株分离物可分为21个类群。研究表明同一菌落形态类型的菌株在系统发育树中不一定聚为一类, 菌落形态分类与分子生物学方法分类结果不完全一致。经克隆测序分析表明, 这267株分离物分别与GenBank中6类细菌中的21个已知种相似性达到98%?99%。其中芽孢杆菌属(Bacillus)细菌是烟草可培养内生细菌的优势种群。     

Primer protein of bacteriophage M2 exposes the RGD receptor site upon linking the first deoxynucleotide

Summary Using electroporation with the phage PRD1 genome, we set up a high-frequency DNA transfer system for a linear dsDNA molecule with 5-covalently linked terminal proteins. The transfer was saturated when more than 100 ng of PRD1 genome was used. Electroporation efficiency was about four orders of magnitude higher than that obtained with transfection. Removal of the terminal protein abolished plaque formation, which could not be rescued by supplying the terminal protein or phage DNA polymerase or both in trans.     

Intrapopulation foraging niche variation between phenotypes and genotypes of Spirit bear populations

Foraging niche variation within a species can contribute to the maintenance of phenotypic diversity. The multiniche model posits that phenotypes occupying different niches can contribute to the maintenance of balanced polymorphisms. Using coastal populations of black bears (Ursus americanus kermodei) from British Columbia, Canada, we examined potential foraging niche divergence between phenotypes (black and white “Spirit” coat color) and between genotypes (black‐coated homozygote and heterozygous). We applied the Bayesian multivariate models, with biotracers of diet (δ¹³C and δ¹⁵N) together comprising the response variable, to draw inference about foraging niche variation. Variance–covariance matrices from multivariate linear mixed‐effect models were visualized as the Bayesian standard ellipses in δ¹³C and δ¹⁵N isotopic space to assess potential seasonal and annual niche variation between phenotypes and genotypes. We did not detect a difference in annual isotopic foraging niche area in comparisons between genotypes or phenotypes. Consistent with previous field experimental and isotopic analyses, however, we found that white phenotype Spirit bears were modestly more enriched in δ¹⁵N during the fall foraging season, though with our modest sample sizes these results were not significant. Although also not statistically significant, variation in isotopic niches between genotypes revealed that heterozygotes were moderately more enriched in δ¹³C along hair segments grown during fall foraging compared with black‐coated homozygotes. To the extent to which the pattern of elevated δ¹⁵N and δ¹³C may signal the consumption of salmon (Oncorhynchus spp.), as well as the influence of salmon consumption on reproductive fitness, these results suggest that black‐coated heterozygotes could have a minor selective advantage in the fall compared with black‐coated homozygotes. More broadly, our multivariate approach, coupled with knowledge of genetic variation underlying a polymorphic trait, provides new insight into the potential role of a multiniche mechanism in maintaining this rare morph of conservation priority in Canada''s Great Bear Rainforest and could offer new understanding into polymorphisms in other systems.     

A single amino acid substitution alters ClpS2 binding specificity

ClpS2 is a small protein under development as a probe for selectively recognizing N-terminal amino acids of N-degron peptide fragments. To understand the structural basis of ClpS2 specificity for an N-terminal amino acid, all atom molecular dynamics (MD) simulations were conducted using the sequence of a bench-stable mutant of ClpS2, called PROSS. We predicted that a single amino acid leucine to asparagine substitution would switch the specificity of PROSS ClpS2 to an N-terminal tyrosine over the preferred phenylalanine. Experimental validation of the mutant using a fluorescent yeast-display assay showed an increase in tyrosine binding over phenylalanine, in support of the proposed hypothesis.     

A splice variant of the Drosophila vesicular monoamine transporter contains a conserved trafficking domain and functions in the storage of dopamine, serotonin, and octopamine

Vesicular monoamine transporters (VMATs) mediate the transport of dopamine (DA), serotonin (5HT), and other monoamines into secretory vesicles. The regulation of mammalian VMAT and the related vesicular acetylcholine transporter (VAChT) has been proposed to involve membrane trafficking, but the mechanisms remain unclear. To facilitate a genetic analysis of vesicular transporter function and regulation, we have cloned the Drosophila homolog of the vesicular monoamine transporter (dVMAT). We identify two mRNA splice variants (DVMAT-A and B) that differ at their C-terminus, the domain responsible for endocytosis of mammalian VMAT and VAChT. DVMAT-A contains trafficking motifs conserved in mammals but not C. elegans, and internalization assays indicate that the DVMAT-A C-terminus is involved in endocytosis. DVMAT-B contains a divergent C-terminal domain and is less efficiently internalized from the cell surface. Using in vitro transport assays, we show that DVMAT-A recognizes DA, 5HT, octopamine, tyramine, and histamine as substrates, and similar to mammalian VMAT homologs, is inhibited by the drug reserpine and the environmental toxins 2,2,4,5,6-pentachlorobiphenyl and heptachlor. We have developed a specific antiserum to DVMAT-A, and find that it localizes to dopaminergic and serotonergic neurons as well as octopaminergic, type II terminals at the neuromuscular junction. Surprisingly, DVMAT-A is co-expressed at type II terminals with the Drosophila vesicular glutamate transporter. Our data suggest that DVMAT-A functions as a vesicular transporter for DA, 5HT, and octopamine in vivo, and will provide a powerful invertebrate model for the study of transporter trafficking and regulation.     

The Effects of Silicone Fluid Additives and Silicone Elastomer Matrices on Barnacle Adhesion Strength

Barnacle adhesion strength was used to screen seventy-seven polydimethylsiloxane elastomeric coatings for fouling-release properties. The test coatings were designed to investigate the effect on barnacle adhesion strength of silicone fluid additive type, additive location, additive molecular weight, additive loading level, mixtures of additives, coating matrix type and coating fillers. The type of silicone fluid additive was the primary controlling factor in barnacle fouling-release. The type of silicone matrix in which the fluid resided was found to alter the effect on fouling-release. Two PDMS fluids, DMSC15 and DBE224, significantly reduced the adhesion strength of barnacles compared to unmodified elastomers. Optimum fouling-release performance was dependent on the interaction of fluid type and elastomeric matrix.     

Blockade of IL-36 Receptor Signaling Does Not Prevent from TNF-Induced Arthritis

Introduction

Interleukin (IL)-36α is a newly described member of the IL-1 cytokine family with a known inflammatory and pathogenic function in psoriasis. Recently, we could demonstrate that the receptor (IL-36R), its ligand IL-36α and its antagonist IL-36Ra are expressed in synovial tissue of arthritis patients. Furthermore, IL-36α induces MAP-kinase and NFκB signaling in human synovial fibroblasts with subsequent expression and secretion of pro-inflammatory cytokines.

Methods

To understand the pathomechanism of IL-36 dependent inflammation, we investigated the biological impact of IL-36α signaling in the hTNFtg mouse. Also the impact on osteoclastogenesis by IL-36α was tested in murine and human osteoclast assays.

Results

Diseased mice showed an increased expression of IL-36R and IL-36α in inflamed knee joints compared to wildtype controls. However, preventively treating mice with an IL-36R blocking antibody led to no changes in clinical onset and pattern of disease. Furthermore, blockade of IL-36 signaling did not change histological signs of TNF-induced arthritis. Additionally, no alteration on bone homeostasis was observed in ex vivo murine and human osteoclast differentiation assays.

Conclusion

Thus we conclude that IL-36α does not affect the development of inflammatory arthritis.