实蝇共生菌研究进展

实蝇类昆虫(双翅目Diptera:实蝇科Tephritidae)是重要的农业害虫,为害农作物茎秆和水果,严重影响农业生产和果蔬贸易,被许多国家列为重要的检疫性有害生物。实蝇共生菌对宿主实蝇的取食、生殖、发育及环境适应能力具有重要作用。目前,已有21个属的共生细菌(Enterobacter、Klebsiella、Citrobacter、Pseudomonas、Providencia、Erwinia、Acetobacter、Serratia、Proteus、Hafnia、Cedecea、Arthrobacter、Lactobacillus、Micrococcus、Streptococcus、Staphylococcus、Vibrio、Hafnia、Deinococcacea、Bacillus、Wolba-chia)以及1个属的共生真菌(Candida)被鉴定。其中,肺炎杆菌Klebsiella pneumoniae、产酸克雷伯氏菌Klebsiella oxytoca、成团泛菌Pantoea agglomerans、费氏柠檬酸杆菌Citrobter freundii、阴沟肠杆菌Enterobacter cloaca...     

2'Halo-ATP and -GTP analogues: rational phasing tools for protein crystallography

The solution of the crystallographic macromolecular phase problem requires incorporation of heavy atoms into protein crystals. Several 2'-halogenated nucleotides have been reported as potential universal phasing tools for nucleotide binding proteins. However, only limited data are available dealing with the effect of 2'-substitution on recognition by the protein. We have determined equilibrium dissociation constants of 2'-halogenated ATP analogues for the ATP binding proteins UMP/CMP kinase and the molecular chaperone DnaK. Whereas the affinities to UMP/CMP kinase are of the same order of magnitude as for unsubstituted ATP, the affinities to DnaK are drastically decreased to undetectable levels. For 2'-halogenated GTP analogues, the kinetics of interaction were determined for the small GTPases p21ras(Y32W) (fluorescent mutant) and RabS. The rates of association were found to be within about one order of magnitude of those for the nonsubstituted nucleotides, whereas the rates of dissociation were accelerated by factors of approximately 100 (p21ras) or approximately 10(5) (Rab5), and the resulting equilibrium dissociation constants are in the nm or microM range, respectively. The data demonstrate that 2'halo-ATP and -GTP are substrates or ligands for all proteins tested except the chaperone DnaK. Due to the very high affinities of a large number of GTP binding proteins to guanine nucleotides, even a 10(5)-fold decrease in affinity as observed for Rab5 places the equilibrium dissociation constant in the microM range, so that they are still well suited for crystallization of the G-protein:nucleotide complex.     

微生物肥料及其生产应用中的问题

微生物肥料和微生物制剂是新世纪实行绿色农业的重要技术保障,关键是因其中含有大量的有效微生物的生命活动产生特定的肥效或其他生理功能,导致增产,微生物肥料包括根瘤菌肥,解磷菌肥、解钾菌肥、5406菌肥,植物根际促生菌,VA菌根等等,有机肥料堆制剂中含有多种降解农业有机废料的菌种,可缩短堆肥周期,提高养份利用率,由于微生物本身的特殊性,相关市场监督机制不健全,微生物肥料的生产,应用领域存在很多问题,甚至出现明显的伪科学,科研、生产、行政各有关部门应加强基础研究,提高全民科普水平,健全市场监督机制,依靠专家设计严格试验,优选可靠技术,保证良好的经济效益和社会效益。     

连作障碍因素对大豆养分吸收和固氮作用的影响

采用分室装置,利用不同孔径的膜研究大豆连作条件下,化感物质、土壤有害生物和大豆胞囊线虫等因素不断累加对植株生长、生物固氮作用和矿质养分吸收和分配的影响。结果表明,随着各因素不断累加,植株的地上部、根系和根瘤干重逐渐降低;除Ca元素外,植株组织的P、K等矿质元素单位含量下降,吸收总量下降,地上部分配的养分比例下降。在化感物质和土壤有害生物因素的基础上接种线虫,对生物固氮和矿质养 分的吸收和分配影响明显。     

不同改良措施对太子参根际土壤酚酸含量及特异菌群的影响

太子参为石竹科多年生草本植物,以根部入药,药用价值高,市场需求大,但其栽培过程中存在严重的连作障碍问题,连作导致产量品质严重下降,病虫害猖獗,探索太子参连作障碍形成的机制及其消减措施意义重大.本研究以广泛栽培的“柘参2号”为试验材料,采用土壤农化分析、高效液相色谱(HPLC)分析、荧光定量PCR(qPCR)等技术对不同连作年限或不同消减措施下太子参根际土壤的主要养分、酚酸含量动态及特异菌群变化进行分析.结果显示: 太子参连作导致产量显著下降,与正茬相比产量下降达43.5%,而水旱轮作和微生物菌肥处理可不同程度缓解其障碍效应.太子参连作土壤主要养分(如速效氮、速效磷、速效钾、全钾)未降反升,但导致土壤酸化.HPLC分析表明,太子参连作下或者随生长时期的推进,土壤酚酸类物质并未表现出明显的积累效应,膨大中期和收获期重茬土壤中大部分酚酸含量甚至低于正茬土壤.进一步荧光定量PCR分析发现,太子参连作导致前期分离筛选到的几类病原菌(如尖孢镰刀菌、踝节霉菌、Kosakonia sacchari)的绝对含量显著上升,而水旱轮作和微生物菌肥处理可有效降低3类病原菌的含量,改善微生态结构.综上认为,太子参连作障碍的发生并非由土壤养分匮乏或者酚酸持续积累直接造成,可能主要与连作下土传病原微生物的大量繁殖爆发有关,本研究结果为深入揭示太子参连作障碍的形成机制及消减修复机制提供了理论依据.     

基于Progressive多序列比对方法的求解多序列比对的启发式算法

在生物信息学研究中,生物序列比对问题占有重要的地位。多序列比对问题是一个NPC问题,由于时间和空间的限制不能够求出精确解。文中简要介绍了Feng和Doolittle提出的多序列比对算法的基本思想,并改进了该算法使之具有更好的比对精度。实验结果表明,新算法对解决一般的progressive多序列比对方法中遇到的局部最优问题有较好的效果。     

A new solution for maximal clique problem based sticker model

In this paper, we use stickers to construct a solution space of DNA for the maximal clique problem (MCP). Simultaneously, we also apply the DNA operation in the sticker-based model to develop a DNA algorithm. The results of the proposed algorithm show that the MCP is resolved with biological operations in the sticker-based model for the solution space of the sticker. Moreover, this work presents clear evidence of the ability of DNA computing to solve the NP-complete problem. The potential of DNA computing for the MCP is promising given the operational time complexity of O(nxk).     

中国地级区域高质量发展格局与影响因素

高质量发展战略对中国生态经济系统的运行提出了更高要求。当前对高质量发展的研究侧重经济子系统,对生态子系统和社会子系统的分析相对薄弱,且缺乏省级以下中微观尺度的分析。从经济质量、创新潜力、环境质量、生态安全、人民生活和城乡协调六个维度解析了高质量发展内涵,搜集了全国306个地级区域2018年的数据资料,构建地级区域高质量发展综合评价指标体系,定量测算了地级区域高质量发展指数,揭示了区域格局,考察了影响因素,识别了问题区域,并提出了发展质量提升策略。研究表明：(1)高质量发展指数存在明显的区域差异,东部地区和长江流域发展水平相对较高,东北地区和黄河流域发展水平相对较低。(2)经济质量、创新潜力和人民生活指数的均值相对较低,是高质量发展的薄弱环节。(3)高质量发展水平受到自然环境适宜性、城市等级和人口集聚、投资水平、交通区位、数字经济等因素的综合影响,且具有较强的空间溢出效应。(4)识别出8大类174个高质量发展的问题地市,分布在26个省区,在黄河流域和东北地区相对集中。最后,从制度建设、全国层面和具体区域层面探讨了高质量发展水平提升路径,可为制定区域发展战略和区域政策提供科学参考。     

基于主体功能区的长江经济带绿色发展评价与问题区域识别

长江经济带已成为我国推进绿色发展的重要阵地。基于主体功能区视角,构建以水系统为纽带的长江经济带绿色发展评价指标体系,采用综合加权法、空间自相关、耦合协调度模型等方法探究2018年长江经济带130个城市绿色发展及各子系统耦合协调水平的空间格局,并对绿色发展的问题区域进行分类识别。结果表明：(1)长江经济带绿色发展水平呈由下游、中游至上游递减趋势;各主体功能区绿色发展指数表现为优化开发区>限制开发区>重点开发区。(2)绿色发展各子系统耦合协调度值位于0.365—0.656之间,多处于濒临失调和勉强协调的临界区间,耦合协调水平整体偏低。(3)从长江经济带整体来看,长江中上游地区绝大部分城市绿色发展主要受资源利用和产业发展水平偏低,及由此带来的生态和生活问题限制,且长江中上游地区各省会或直辖市对区域内其他城市绿色发展带动能力不足。从主体功能区视角来看,优化开发区以生态问题为主,仅上海和嘉兴两市;重点开发区以生态和生产问题为主,集中于武汉都市圈和成渝双城经济圈内部;限制开发区以生产和生活问题为主,主要位于省际边界型城市地区。最后综合问题识别结果,分别对长江经济带各主要问题区域绿色发展...     

Preliminary results of a new approach for three-dimensional reconstruction of Dynamic AngioThermography (DATG) images based on the inversion of heat equation

Dynamic AngioThermography (DATG) is a contact-plate technique capable of producing a digital representation of breast vascularity. The inception and growth of a tumor are associated with neoangenesis, which may result in a demonstrable alteration in the regional blood flow, while in normal health conditions the vascularity remains unchanged throughout life. DATG, if included in the clinical evaluation for breast cancer, could potentially improve the accuracy of the diagnosis of this disease.Conventional DATG is limited, however, in that it is a projection (i.e. two-dimensional) imaging technique that does not provide any information on the depth and its effect on the pattern of the perfusion revealed by this technique. In fact, the blood pattern is detected by projecting temperature signals on the plate, thus acquiring a digital two-dimensional image.In this article we propose a new approach for extracting information on depth through the inversion of the Fourier heat equation. The idea is to extract the information along the third axis while acquiring and analyzing the temporal sequence during the process of image formation. The method implemented has been tested on a dedicated “electric phantom” and in one in vivo experiment.In spite of the limits of these preliminary tests, the experimental results have shown that this method makes it possible to obtain a 3D representation of the vascularity. Although it appears to be promising, further validation and characterization of our technique are required.