Crystal Structure of the Engineered Neutralizing Antibody M18 Complexed to Domain 4 of the Anthrax Protective Antigen

The virulence of Bacillus anthracis is critically dependent on the cytotoxic components of the anthrax toxin, lethal factor (LF) and edema factor (EF). LF and EF gain entry into host cells through interactions with the protective antigen (PA), which binds to host cellular receptors such as CMG2. Antibodies that neutralize PA have been shown to confer protection in animal models and are undergoing intense clinical development. A murine monoclonal antibody, 14B7, has been reported to interact with domain 4 of PA (PAD4) and block its binding to CMG2. More recently, the 14B7 antibody was used as the platform for the selection of very high affinity, single-chain antibodies that have tremendous potential as a combination anthrax prophylactic and treatment. Here, we report the high-resolution X-ray structures of three high-affinity, single-chain antibodies in the 14B7 family; 14B7 and two high-affinity variants 1H and M18. In addition, we present the first neutralizing antibody-PA structure, M18 in complex with PAD4 at 3.8 Å resolution. These structures provide insights into the mechanism of neutralization, and the effect of various mutations on antibody affinity, and enable a comparison between the binding of the M18 antibody and CMG2 with PAD4.     

Fusion protein of Δ27LFn and EFn has the potential as a novel anthrax toxin inhibitor

PA-binding domain of LF (LFn) or PA-binding domain of EF (EFn) is the anthrax protective antigen (PA) binding domain of anthrax lethal factor (LF) or edema factor (EF). Here we show the development of a novel anthrax toxin inhibitor, fusion protein of N-terminal 27 amino acids deletion of LFn (Δ27LFn) and EFn. In a cell model of intoxication, fusion protein of Δ27LFn and EFn (Δ27LFn-EFn) was a 62-fold more potent toxin inhibitor than LFn or EFn, and this increased activity corresponded to a 39-fold higher PA-binding affinity by Biacore analysis. More importantly, Δ27LFn-EFn could protect the highly susceptible Fischer 344 rats from anthrax lethal toxin challenge. This work suggested that Δ27LFn-EFn has the potential as a candidate therapeutic agent against anthrax.

Structured summary

MINT-7014735, MINT-7014747, MINT-7014761: PA63 (uniprotkb:P13423) and LF (uniprotkb:P15917) bind (MI:0407) by surface plasmon resonance (MI:0107)     

外源茉莉酸诱导的青杨叶片保护性酶活性变化及其对舞毒蛾幼虫生长发育的影响

为探讨外源茉莉酸对青杨Populus cathayana的诱导抗性及其对舞毒蛾Lymantria dispar的影响, 室内对青杨扦插苗喷施不同浓度的茉莉酸（对照为0.17%丙酮）, 分别在喷施后1, 5和10 d采集叶片分析其保护性酶活性的变化, 并接舞毒蛾幼虫于青杨苗木上观测其长发育情况。结果表明： 0.1 和0.001 mmol/L两种浓度的茉莉酸（JA）处理均使青杨叶过氧化物酶（POD）、 多酚氧化酶（PPO）、 苯丙氨酸解氨酶（PAL）、 胰凝乳蛋白酶抑制剂（CI）和胰蛋白酶抑制剂（TI）活性较对照增加(P<0.05)。取食茉莉酸诱导的青杨苗木后, 舞毒蛾幼虫的发育历期延长, 体重降低。0.1 mmol/L茉莉酸诱导的青杨苗木5 d后接虫, 使舞毒蛾幼虫的发育历期显著延长, 较对照长8 d; 接虫21 d后称重时, 取食茉莉酸诱导的青杨叶片的幼虫体重较对照组降低了50%~100%, 该结果说明外源茉莉酸诱导青杨产生了对舞毒蛾明显的抗虫性。     

α-萜品醇熏蒸对大麦虫体内抗氧化酶活性的影响

为研究植物挥发性有机化合物α-萜品醇的杀虫活性及作用机理, 本研究采用熏蒸法测定了α-萜品醇对大麦虫Zophobas morio（鞘翅目： 拟步行甲科）4龄幼虫的急性毒性, 并测定了不同熏蒸时间后幼虫体内超氧化物歧化酶（SOD）、 过氧化物酶（POD）和过氧化氢酶（CAT）活性。结果表明： 熏蒸48 h时, α-萜品醇对大麦虫4龄幼虫的LC₅₀和LC₂₀值分别为69.425 μg/L和59.916 μg/L。α-萜品醇（LC₂₀和LC₅₀）处理的4龄幼虫SOD, POD和CAT活性均表现为先升高后降低的趋势。据此推测, α-萜品醇在幼虫体内积累显著影响幼虫体内SOD, POD和CAT活性, 降低虫体内自由基的清除能力, 从而对其产生毒害作用。     

防护林学研究现状与展望

防护林学是研究防护林构建及经营的理论与技术的科学, 其核心内容包括防护林构建理论与技术、防护林经营理论与技术和防护林效益评价。防护林学发展的终极目的是构建与经营防护林, 使其防护功能或生态服务功能高效、稳定并可持续。防护林学是偏重实用的应用基础学科, 其发展始终依托防护林工程建设需求, 特别是以国家运作方式开展的大型防护林工程建设, 对推动防护林学发展做出了巨大贡献。国外著名的防护林工程有美国大平原各州林业工程(罗斯福工程)、前苏联斯大林改造大自然计划、日本的治山治水防护林工程和北非五国“绿色坝”跨国防护林工程等。围绕这些工程, 在防护林规划设计、树种选择、空间配置、造林方法, 结构、抚育、间伐、衰退机制与更新, 以及效益评价等各个方面开展了相关研究, 其中, 以效益评价及效益与结构的关系研究最为广泛与深入。中国幅员辽阔、自然条件复杂、森林资源相对匮乏且分布不均、自然环境恶劣, 对防护林的需求极大, 自“三北”防护林体系建设工程启动以来, 中国防护林建设规模已居世界首位, 防护林学在中国得到了长足发展, 尤其在防护林经营理论与技术研究方面取得突破性进展。防护林学以效益评价为桥梁将防护林构建和经营组合在一起, 效益与结构的关系为防护林构建及现有防护林经营提供了科学依据。未来防护林学研究将以更广泛的生态公益林或防护性森林为对象, 在研究方法上将由以林分尺度为主向更微观和更宏观两个方向拓展; 在防护林构建方面, 仍以林学理论与技术为主体, 并重点与生态系统稳定性原理、景观生态学原理相结合, 开展防护林(体系)区域分异规划设计、营建理论与技术研究; 在防护林经营方面, 将以防护林衰退与恢复机制、带状防护林更新和非带状防护林近自然经营理论与技术为重点开展研究; 在效益评价方面, 将采用遥感等技术, 以防护林(体系)、大规模防护林建设的生态环境效应评价等为主要内容开展研究。     

Risk and protective factors for mental disorders beyond genetics: an evidence‐based atlas

Decades of research have revealed numerous risk factors for mental disorders beyond genetics, but their consistency and magnitude remain uncer­tain. We conducted a “meta‐umbrella” systematic synthesis of umbrella reviews, which are systematic reviews of meta‐analyses of individual studies, by searching international databases from inception to January 1, 2021. We included umbrella reviews on non‐purely genetic risk or protective factors for any ICD/DSM mental disorders, applying an established classification of the credibility of the evidence: class I (convincing), class II (highly suggestive), class III (suggestive), class IV (weak). Sensitivity analyses were conducted on prospective studies to test for temporality (reverse causation), TRANSD criteria were applied to test transdiagnosticity of factors, and A Measurement Tool to Assess Systematic Reviews (AMSTAR) was employed to address the quality of meta‐analyses. Fourteen eligible umbrella reviews were retrieved, summarizing 390 meta‐analyses and 1,180 associations between putative risk or protective factors and mental disorders. We included 176 class I to III evidence associations, relating to 142 risk/protective factors. The most robust risk factors (class I or II, from prospective designs) were 21. For dementia, they included type 2 diabetes mellitus (risk ratio, RR from 1.54 to 2.28), depression (RR from 1.65 to 1.99) and low frequency of social contacts (RR=1.57). For opioid use disorders, the most robust risk factor was tobacco smoking (odds ratio, OR=3.07). For non‐organic psychotic disorders, the most robust risk factors were clinical high risk state for psychosis (OR=9.32), cannabis use (OR=3.90), and childhood adversities (OR=2.80). For depressive disorders, they were widowhood (RR=5.59), sexual dysfunction (OR=2.71), three (OR=1.99) or four‐five (OR=2.06) metabolic factors, childhood physical (OR=1.98) and sexual (OR=2.42) abuse, job strain (OR=1.77), obesity (OR=1.35), and sleep disturbances (RR=1.92). For autism spectrum disorder, the most robust risk factor was maternal overweight pre/during pregnancy (RR=1.28). For attention‐deficit/hyperactivity disorder (ADHD), they were maternal pre‐pregnancy obesity (OR=1.63), maternal smoking during pregnancy (OR=1.60), and maternal overweight pre/during pregnancy (OR=1.28). Only one robust protective factor was detected: high physical activity (hazard ratio, HR=0.62) for Alzheimer’s disease. In all, 32.9% of the associations were of high quality, 48.9% of medium quality, and 18.2% of low quality. Transdiagnostic class I‐III risk/protective factors were mostly involved in the early neurodevelopmental period. The evidence‐based atlas of key risk and protective factors identified in this study represents a benchmark for advancing clinical characterization and research, and for expanding early intervention and preventive strategies for mental disorders.     

A mutation protective against Alzheimer's disease renders amyloid β precursor protein incapable of mediating neurotoxicity

Expression of a familial Alzheimer's disease (AD)‐linked mutant of amyloid β precursor protein (APP) or the binding of transforming growth factor β2 to wild‐type (wt)‐APP causes neuronal death by activating an intracellular death signal (a APP‐mediated intracellular death signal) in the absence of the involvement of amyloid β (Aβ) toxicity in vitro. These neuronal death models may therefore be regarded as Aβ‐independent neuronal death models related to AD. A recent study has shown that the A673T mutation in the APP isoform APP₇₇₀, corresponding to the A598T mutation in the most prevalent neuronal APP isoform APP₆₉₅ (an AD‐protective mutant of APP), is linked to a reduction in the incidence rate of AD. Consistent with this, cells expressing the AD‐protective mutant of APP produce less Aβ than cells expressing wt‐APP. In this study, transforming growth factor β2 caused death in cultured neuronal cells expressing wt‐APP, but not in those expressing the AD‐protective mutant of APP. This result suggests that the AD‐protective mutation of APP reduces the incidence rate of AD by attenuating the APP‐mediated intracellular death signal. In addition, a mutation that causes hereditary cerebral hemorrhage with amyloidosis‐Dutch type also attenuated the APP‐mediated intracellular death signal.

     

Gene Cloning,Expression and Immunogenicity of the Protective Antigen Subolesin in Dermacentor silvarum

Subolesin (4D8), the ortholog of insect akirins, is a highly conserved protective antigen and thus has the potential for development of a broad-spectrum vaccine against ticks and mosquitoes. To date, no protective antigens have been characterized nor tested as candidate vaccines against Dermacentor silvarum bites and transmission of associated pathogens. In this study, we cloned the open reading frame (ORF) of D. silvarum 4D8 cDNA (Ds4D8), which consisted of 498 bp encoding 165 amino acid residues. The results of sequence alignments and phylogenetic analysis demonstrated that D. silvarum 4D8 (Ds4D8) is highly conserved showing more than 81% identity of amino acid sequences with those of other hard ticks. Additionally, Ds4D8 containing restriction sites was ligated into the pET-32(a+) expression vector and the recombinant plasmid was transformed into Escherichia coli rosetta. The recombinant Ds4D8 (rDs4D8) was induced by isopropyl β-D-thiogalactopyranoside (IPTG) and purified using Ni affinity chromatography. The SDS-PAGE results showed that the molecular weight of rDs4D8 was 40 kDa, which was consistent with the expected molecular mass considering 22 kDa histidine-tagged thioredoxin (TRX) protein from the expression vector. Western blot results showed that rabbit anti-D. silvarum serum recognized the expressed rDs4D8, suggesting an immune response against rDs4D8. These results provided the basis for developing a candidate vaccine against D. silvarum ticks and transmission of associated pathogens.     

多氯联苯对桐花树幼苗生长及膜保护酶系统的影响

通过盆栽实验,研究了不同浓度(180、900、1 800和2 700 μg·kg^-1)多氯联苯(PCBs)对红树植物桐花树幼苗生长、叶绿素含量、膜质过氧化产物丙二醛（MDA）以及膜保护酶系统的影响.结果表明：PCBs对桐花树幼苗的生长有一定的促进作用,随着PCBs浓度的提高,桐花树幼苗的茎高、茎径和茎体积均呈升高趋势;在试验PCBs浓度范围内,桐花树幼苗叶片能保持相对正常的叶绿素水平和相对稳定的叶绿素a/b值,叶绿素a、叶绿素b和叶绿素a+b含量虽然有所降低,但均未低于对照的75%;叶绿素a/b值有所升高,但均未超过对照的10％.随着PCBs浓度的提高,桐花树幼苗叶片SOD活性呈单峰曲线变化,而POD活性和MDA含量呈单谷曲线变化.红树植物桐花树可通过生理生化机制适应一定浓度的PCBs污染,对PCBs有较强的耐受性和适应性,可用于PCBs污染的植物修复.     

从恢复生态学视角透析防护林衰退及其防治对策：以章古台地区樟子松林为例

针对防护林衰退问题,以章古台樟子松固沙林为案例,应用生态演替、干扰、种群密度等关键性恢复生态学理论和原则,对防护林在决策层面的设计要素的科学性及其与衰退的关系进行了分析和评价,认为大面积造林与地带性顶极的不吻合（即偏离生态学原则）,使防护林建设的目标、步骤、树种的组成和密度等出现了偏颇,成为防护林衰退的最深层次的原因,疏于管理和粗放经营以及频频发生的自然和人为干扰也是致衰的重要因素;据此提出深化对受损生态系统的认识、强化物质和能量的投入、建立干扰的防控体系等对策.文中还就人工植被建设目标与生态演替顶极类型的判别,以及偏途顶极在人工植被建设中的应用问题进行了讨论,一并作为对策以供参考.