芋螺毒素基因资源研究进展

芋螺毒素和微生物的次生代谢产物与植物的生物碱一样,具有生物多样性的特点。芋螺毒素特有的二硫键骨架和化学修饰后特异的空间结构,使其具有特异的稳定性和药理学活性。对芋螺毒素基因的分析和新型基因的克隆筛选,是深入研究各种受体、离子通道及其亚型,进而在克隆表达的靶受体上设计和筛选高效新药的前提。芋螺毒素基因资源的研究在芋螺毒素新基因及其编码产物毒素肽的发现与利用方面发挥了重要作用。现对该领域的新进展进行论述。     

浓香型白酒糟醅及窖泥产香功能菌的研究进展

浓香型白酒主要香气物为己酸乙酯、乳酸乙酯、乙酸乙酯和丁酸乙酯四大酯类,白酒微生物发酵过程中酯类合成主要是酸与醇在酯化酶的作用下产生,因此产香功能菌包括香气及其前体物产生菌和酯化酶产生菌.本文综述了浓香型白酒糟醅及窖泥主要产香功能菌的来源、组成、鉴定方法、功能特性、相互关系及其在浓香型白酒生产过程中的应用等方面的研究进展,旨为浓香型白酒重要微生物的研究提供思路,为其发酵过程控制提供理论依据.     

微生物降解呋喃丹的研究进展

呋喃丹(2,3-二氢-2,2-二甲基-7-苯并呋喃基甲氨基甲酸酯)是一种曾被广泛应用于农业生产的氨基甲酸酯类杀虫剂。虽然呋喃丹现在是我国的限制使用农药品种,但是它的残留仍然破坏生态环境和威胁人体健康。微生物降解是消除环境中呋喃丹污染的有效手段,但是目前对微生物降解呋喃丹的分子机制还未阐明。本文从微生物菌株资源、降解途径、关键酶和基因等几个方面综合阐述了国内外对微生物降解呋喃丹的最新研究进展,为呋喃丹污染环境的生物修复提供参考。     

微藻无菌化技术的研究进展

无菌纯藻是深入开展藻类生理学和遗传学研究的基础。目前已有涂布划线法,离心洗涤技术、稀释滤过技术、辐照技术、毛细吸管技术、抗生素技术、化学消毒技术、利用其他生理特性等技术用于微藻的纯化。拟介绍国内外近年来微藻无菌纯化技术的研究进展。     

基于SCI文献分析我国菌根学研究现状和发展方向

基于美国科学情报研究所(ISI)科学引文索引(Science Citation Index, SCI)数据库, 对1989~2007年期间我国发表的菌根研究论文进行检索, 并采用文献计量方法对所获资料进行统计和趋势分析。结果表明, 1989~2007年间, 我国菌根学研究呈现不断上升趋势, 尤其是2000年之后, 增长速度明显加快。但只有5.22%的论文发表于影响因子大于5的刊物, 在研究深度上仍需进一步加强。半数以上的研究论文与丛枝菌根研究有关, 研究重点主要集中在菌根对植物的生理效应, 菌根与植物抗性     

Isolation and characterization of lytic bacteriophages from sewage at an egyptian tertiary care hospital against methicillin-resistant Staphylococcus aureus clinical isolates

BackgroundMethicillin resistant Staphylococcus aureus (MRSA) is a pathogen to humans causing life-threatening infections. MRSA have the capability to grow resistance to many antibiotics, and phage therapy is one treatment option for this infection.ObjectivesThe aim of the present study was to isolate and characterize the lytic bacteriophages specific to MRSA from domestic sewage water at a tertiary care hospital in Egypt.MethodsThirty MRSA strains were isolated from different clinical samples admitted to the microbiology lab at Theodor Bilharz Research institute (TBRI) hospital, Giza, Egypt. They were confirmed to be MRSA through phenotypic detection and conventional PCR for mecA gene. They were used for the isolation of phages from sewage water of TBRI hospital. Plaque assay was applied to purify and quantify the titer of the isolated phages. The host range of the isolated phages was detected using the spot test assay. The morphology of phages was confirmed using transmission electron microscope (TEM). Digestion of DNA extracted from phages with endonuclease enzymes including EcoRI and SmaI was performed. SDS-PAGE was performed to analyze MRSA specific phage proteins. As a positive control prophages were isolated from a mitomycin C (MitC) treated culture of S. aureus strain ATCC25923. Further characterization using conventional polymerase chain reaction (PCR) was used to select three known Staphylophages by detecting the endolysin gene of phage K, the polymerase gene of phage 44AHJD, and the minor tail gene of phage P68.ResultsIsolated phages in this research displayed a wide host range against MRSA using the spot test, out of thirty tested MRSA isolates 24 were sensitive and got lysed (80%). The titer of the phages was estimated to be 1.04 × 10⁶ pfu/ml using plaque test. Identification of head and tail morphology of the phages was achieved using TEM and they were designated to tailed phages of order Caudovirales, they composed an icosahedral capsid. Prophages were isolated through MitC induction. DNA of phages was digested by endonuclease enzymes. Conventional PCR yielded 341 bp of phage K endolysin gene and phage P68 minor tail protein gene 501 bp. Protein analysis using SDS-PAGE showed 4 proteins of sizes between 42 kDa and 140 kDa.ConclusionPhages isolated here are alike to others mentioned in previous studies. The high broad host range of the isolated phages is promising to control MRSA and can be in the future commercially suitable for treatment as lysate preparations. Animal models of phage-bacterial interaction will be our next step that may help in resolving the multidrug resistant crisis of MRSA in Egypt.     

中国陆地植被净初级生产力估算模型优化与分析——基于中国生态系统研究网络数据

该研究基于中国生态系统研究网络(CERN)数据对传统CASA模型进行优化,对比两叶模型与优化CASA模型在站点尺度和像元尺度对于8个典型生态站点的植被净初级生产力(NPP)估算精度,选择在像元尺度表现更好的优化CASA模型,结合中国土地覆被数据(ChinaCover)开展2000—2019年中国陆地植被NPP监测与分析。研究结果表明：(1)基于FY2D PAR的优化方案能够有效避免空间插值导致的不确定性问题,显著提高了PAR估算精度;(2)在站点尺度上,两叶模型用于估算典型森林、草地生态系统的NPP表现更好,而在像元尺度上优化CASA模型估算精度更高;(3)在全国尺度上,优化了最大光能利用率、水分胁迫系数以及光合有效辐射计算方法的CASA模型能够较好地模拟中国陆地植被NPP,近20年中国陆地植被NPP变化范围为2.703—2.882 PgC/a,在空间上呈西北低东南高的格局,在时间上呈现波动中缓慢增加的趋势。     

中国荒漠草原的研究态势与热点分析——基于文献计量研究

荒漠草原是我国草原的重要组成部分,对保障粮食安全、生态安全具有极其重要的作用。为了解中国该领域研究态势,运用文献计量方法,基于36年间国内外发表的3651篇论文,分析了发文量、发文来源、被引频次、主要作者、研究机构和研究热点等。结果表明：（1）2000年后关于荒漠草原的论文数量增幅较大,年均发表超160篇,但篇均被引频次、高质量学术期刊发文量和创新性研究成果较少,整体发文质量还有待进一步提高;（2）具有创新性的评价方法和理论研究一直备受关注,而利用荟萃分析方法对某一研究领域进展的分析得到了学者们的认可;（3）韩国栋、宋乃平、卫智军、周广胜等是荒漠草原研究的主要贡献者,内蒙古农业大学和宁夏大学等单位在发文机构合作间的节点上发挥了重要作用,并形成了荒漠草原研究的网络核心,但中文论文研究机构间的合作较英文论文离散程度高,特别是与国外机构的合作相对较少;（4）研究的热点主要集中在人类活动和气候变化对荒漠草原植被-土壤系统的影响、荒漠草原植被生产力及其影响因素、利用孢粉研究植被和环境变迁等方面。未来荒漠草原的研究应加强国内外机构和人员间的合作创新,从多尺度、多维度应用多学科知识、多技术手段,加强人类活动和气候条件相互作用对荒漠草原植物群落结构进化过程、地上与地下生态过程耦联关系、不同营养级之间内在机理的分析和探讨。通过深度挖掘荒漠草原基础数据,以促进高影响力、高质量成果的产出,实现科研成果量变与质变并举、基础研究与实际应用并重,期望能给荒漠草原的相关研究提供借鉴和启发新方向,为中国草地建设和决策提供科学依据。     

酶作为治疗性药物的研究进展

酶制剂作为药物已成为生物制药领域的一个热点。世界各国药典中含有越来越多的酶制剂,其中大部分已成为治疗各种重大疾病的有效药物。酶对底物具有很高的亲和力和特异性,而且能催化多种目标分子转化为所需产物,这两种特性使得酶可作为一种特殊药物执行小分子无法进行的治疗性生物化学反应。利用生物技术开发新的酶类药物,采用化学修饰的手段降低治疗酶的免疫原性及提高其相对稳定性,是目前探索酶类药物的研究方向。本文系统地概述了国内外酶作为治疗性药物的最新研究进展及展望。     

Membrane potential and surface charge densities as possible generalized regulators of membrane protein activities

On the basis of experimental evidence accumulated in studies of coupling and other membranes a theoretical discussion of a “breathing” membrane structure dependent upon a changing transmembrane electrical (electrochemical) gradient is presented. In the case of certain membranes difference of electrical potentials across the membrane (Δψ) is considered as one of important driving forces for some membrane protein folding and/or the arrangement of subunits within some oligomeric proteins. Δψ changes may induce synchronous reversible energetically favourable transitions in the three-dimensional architecture of several spatially separated proteins of the biomembrane. A polyfunctional regulation of levels of activities of spatially separated membrane proteins may be achieved; in some cases alterations of Δψ and surface charge densities may fulfil function of a link in the chain of events triggering membrane-bound activities in response to external stimuli.