Same same but different - Antiviral factors interfering with the infectivity of HIV particles

Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS). Novel strategies to combat this pandemic include the discovery of cellular proteins targeting distinct steps of the HIV replication cycle. Here, we summarize our current knowledge on antiviral proteins interfering with the infectivity of released HIV particles.     

The Ability of Tetrahymena utriculariae (Ciliophora,Oligohymenophorea) to Colonize Traps of Different Species of Aquatic Carnivorous Utricularia

The host specificity of the recently described ciliate species Tetrahymena utriculariae was tested in a greenhouse growth experiment, which included 14 different species of aquatic Utricularia as potential host plants. We confirmed the high specificity of the interaction between U. reflexa and T. utriculariae, the former being the only tested host species able to maintain colonization for prolonged time periods. We conclude that this plant–microbe relationship is a unique and specialized form of digestive mutualism and the plant–microbe unit a suitable experimental system for future ecophysiological studies.     

Oligomerization of RIG‐I and MDA5 2CARD domains

The innate immune system is the first line of defense against invading pathogens. The retinoic acid‐inducible gene I (RIG‐I) like receptors (RLRs), RIG‐I and melanoma differentiation‐associated protein 5 (MDA5), are critical for host recognition of viral RNAs. These receptors contain a pair of N‐terminal tandem caspase activation and recruitment domains (2CARD), an SF2 helicase core domain, and a C‐terminal regulatory domain. Upon RLR activation, 2CARD associates with the CARD domain of MAVS, leading to the oligomerization of MAVS, downstream signaling and interferon induction. Unanchored K63‐linked polyubiquitin chains (polyUb) interacts with the 2CARD domain, and in the case of RIG‐I, induce tetramer formation. However, the nature of the MDA5 2CARD signaling complex is not known. We have used sedimentation velocity analytical ultracentrifugation to compare MDA5 2CARD and RIG‐I 2CARD binding to polyUb and to characterize the assembly of MDA5 2CARD oligomers in the absence of polyUb. Multi‐signal sedimentation velocity analysis indicates that Ub₄ binds to RIG‐I 2CARD with a 3:4 stoichiometry and cooperatively induces formation of an RIG‐I 2CARD tetramer. In contrast, Ub₄ and Ub₇ interact with MDA5 2CARD weakly and form complexes with 1:1 and 2:1 stoichiometries but do not induce 2CARD oligomerization. In the absence of polyUb, MDA5 2CARD self‐associates to forms large oligomers in a concentration‐dependent manner. Thus, RIG‐I and MDA5 2CARD assembly processes are distinct. MDA5 2CARD concentration‐dependent self‐association, rather than polyUb binding, drives oligomerization and MDA5 2CARD forms oligomers larger than tetramer. We propose a mechanism where MDA5 2CARD oligomers, rather than a stable tetramer, function to nucleate MAVS polymerization.     

Chitosan‐triggered immunity to Fusarium in chickpea is associated with changes in the plant extracellular matrix architecture,stomatal closure and remodeling of the plant metabolome and proteome

Pathogen‐/microbe‐associated molecular patterns (PAMPs/MAMPs) initiate complex defense responses by reorganizing the biomolecular dynamics of the host cellular machinery. The extracellular matrix (ECM) acts as a physical scaffold that prevents recognition and entry of phytopathogens, while guard cells perceive and integrate signals metabolically. Although chitosan is a known MAMP implicated in plant defense, the precise mechanism of chitosan‐triggered immunity (CTI) remains unknown. Here, we show how chitosan imparts immunity against fungal disease. Morpho‐histological examination revealed stomatal closure accompanied by reductions in stomatal conductance and transpiration rate as early responses in chitosan‐treated seedlings upon vascular fusariosis. Electron microscopy and Raman spectroscopy showed ECM fortification leading to oligosaccharide signaling, as documented by increased galactose, pectin and associated secondary metabolites. Multiomics approach using quantitative ECM proteomics and metabolomics identified 325 chitosan‐triggered immune‐responsive proteins (CTIRPs), notably novel ECM structural proteins, LYM2 and receptor‐like kinases, and 65 chitosan‐triggered immune‐responsive metabolites (CTIRMs), including sugars, sugar alcohols, fatty alcohols, organic and amino acids. Identified proteins and metabolites are linked to reactive oxygen species (ROS) production, stomatal movement, root nodule development and root architecture coupled with oligosaccharide signaling that leads to Fusarium resistance. The cumulative data demonstrate that ROS, NO and eATP govern CTI, in addition to induction of PR proteins, CAZymes and PAL activities, besides accumulation of phenolic compounds downstream of CTI. The immune‐related correlation network identified functional hubs in the CTI pathway. Altogether, these shifts led to the discovery of chitosan‐responsive networks that cause significant ECM and guard cell remodeling, and translate ECM cues into cell fate decisions during fusariosis.     

Ptr1 evolved convergently with RPS2 and Mr5 to mediate recognition of AvrRpt2 in diverse solanaceous species

The Ptr1 (Pseudomonas tomato race 1) locus in Solanum lycopersicoides confers resistance to strains of Pseudomonas syringae pv. tomato expressing AvrRpt2 and Ralstonia pseudosolanacearum expressing RipBN. Here we describe the identification and phylogenetic analysis of the Ptr1 gene. A single recombinant among 585 F2 plants segregating for the Ptr1 locus was discovered that narrowed the Ptr1 candidates to eight nucleotide‐binding leucine‐rich repeat protein (NLR)‐encoding genes. From analysis of the gene models in the S. lycopersicoides genome sequence and RNA‐Seq data, two of the eight genes emerged as the strongest candidates for Ptr1. One of these two candidates was found to encode Ptr1 based on its ability to mediate recognition of AvrRpt2 and RipBN when it was transiently expressed with these effectors in leaves of Nicotiana glutinosa. The ortholog of Ptr1 in tomato and in Solanum pennellii is a pseudogene. However, a functional Ptr1 ortholog exists in Nicotiana benthamiana and potato, and both mediate recognition of AvrRpt2 and RipBN. In apple and Arabidopsis, recognition of AvrRpt2 is mediated by the Mr5 and RPS2 proteins, respectively. Phylogenetic analysis places Ptr1 in a distinct clade compared with Mr5 and RPS2, and it therefore appears to have arisen by convergent evolution for recognition of AvrRpt2.     

‘培矮64S’与其eui突变体‘长选3S’穗颈节间蛋白质组差异分析

为从蛋白质表达水平了解长穗颈温敏核不育水稻穗颈节间伸长机理,该研究以长穗颈(EUI)温敏核不育水稻‘长选3S’为材料,温敏核不育水稻‘培矮64S’为对照,采用固相pH梯度双向凝胶电泳和质谱分析方法,对2个水稻材料抽穗前2 d的穗颈节间蛋白质进行分离,并进行差异蛋白质组学的比较研究。结果表明:(1)获得了分辨率和重复性较好的双向凝胶电泳图谱。(2)对40个差异蛋白质点进行MALDI-TOF-TOF-MS肽质谱指纹图谱分析,成功鉴定其中27个差异蛋白质点;与‘培矮64S’相比,‘长选3S’中有17个上调表达和10个下调表达的蛋白质。(3)差异蛋白质按照其功能可分为6类,其中主要是与细胞代谢相关蛋白,其次是与细胞壁重建相关蛋白;并且这些差异蛋白质可能与‘长选3S’抽穗期穗颈节间剧烈伸长生长有关,尤其是细胞壁重建相关蛋白与细胞的伸长密切相关。(4)实时荧光定量PCR对随机挑选的蛋白点2、7、8、24、35和36所对应的基因在两个材料最上节间的表达结果显示,‘长选3S’的2(Os10g08550)、7(Os12g42876)、8(Os01g55830)基因的表达量较‘培矮64S’明显下调,而24(Os06g48760)、35(Os05g25850)、36(Os07g42300)基因的表达量较‘培矮64S’显著上调,表明q-PCR的结果与蛋白凝胶图分析结果一致。研究认为,水稻eui基因可能是通过调节抽穗期穗颈节间这些蛋白质的表达,从而促进穗颈节间细胞分裂,尤其是细胞的伸长生长。     

儿童反复呼吸道感染与肠道微生态变化的相关性

目的研究儿童反复呼吸道感染与患儿肠道微生态平衡紊乱的关系。方法选择102例反复呼吸道感染患儿为研究组,167例急性肺炎患儿为肺炎对照组,142例健康体检儿童为正常对照组。采用16S rRNA荧光定量PCR检测3组对象肠道双歧杆菌及大肠埃希菌数量,计算B/E值,并比较3组研究对象细胞免疫功能。结果正常对照组、肺炎对照组以及研究组儿童肠道双歧杆菌数量依次降低,大肠埃希菌依次增多,B/E值依次降低,差异均有统计学意义(均P0.05)。正常对照组、肺炎对照组以及研究组儿童血液中CD3~+、CD4~+细胞水平以及CD4~+/CD8~+依次降低,CD8~+细胞水平依次增高,差异均有统计学意义(均P0.05)。结论儿童反复呼吸道感染与肠道微生态失衡具有一定相关性,肠道微生态稳态的维持可为反复呼吸道感染的防治提供新思路。     

微生态制剂在早期结直肠癌根治术后的作用

目的探讨微生态制剂在早期结直肠癌(CRC)根治术后的作用,并为此类患者提供一种术后康复支持疗法。方法选取2017年6月-2019年6月于本院接受早期CRC根治术术后97例患者作为研究对象,采用随机数字表分为观察组50例和对照组47例。两组术后均接受常规治疗,观察组在对照组基础上接受双歧杆菌三联活菌胶囊治疗,比较两组治疗前后细胞免疫指标、肠道微生态复杂度及属水平相对丰度、肠道菌群OTU数量、肠道黏膜屏障功能。结果治疗后观察组NK细胞、CD3~+T、CD4~+T、CD4~+/CD8~+T均提高(P0.05),观察组CD8~+T治疗前后相近(P0.05);治疗后对照组上述指标与治疗前差异均无统计学意义(P0.05),观察组NK细胞、CD3~+T、CD4~+T、CD4~+/CD8~+T均高于对照组(P0.05);治疗后观察组Chao1指数、Shannon指数、肠道菌群OTU数均升高(P0.05),对照组Chao1指数、Shannon指数、肠道菌群OTU数量治疗前后差异均无统计学意义(P0.05);治疗后观察组Chao1指数、Shannon指数、肠道菌群OTU数量均高于对照组(P0.05);治疗后观察组大肠杆菌、肠球菌、葡萄球菌属水平相对丰度均下降(P0.05),对照组均升高(P0.05),且观察组均低于对照组(P0.05);治疗后观察组乳杆菌、双歧杆菌、梭菌、类杆菌、链球菌属水平相对丰度均升高(P0.05),对照组均下降(P0.05),且观察组均高于对照组(P0.05);治疗后观察组血浆D-乳酸、DAO、I-FABP、内毒素水平分别为(6.94±1.23)mg/L、(3.45±0.65)U/L、(43.95±7.99)μg/L、(4.48±0.85)U/L,均较治疗前下降(P0.05),对照组各项指标水平分别为(15.59±2.79)mg/L、(7.74±1.35)U/L、(74.21±13.82)μg/L、(8.68±1.65)U/L,均较治疗前升高(P0.05),治疗后观察组血浆D-乳酸、DAO、I-FABP、内毒素水平均降低(P0.05)。结论微生态制剂可有效改善早期CRC患者根治术后的细胞免疫水平,有效纠正早期CRC术后患者肠道菌群失调,增强早期CRC根治术后患者肠黏膜屏障功能。