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1.
Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is triggered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing industries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria's virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following: (1) the inhibition of signal molecule biosynthesis, (2) blocking signal transduction, and (3) chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper. 相似文献
2.
Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is triggered via
auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher
bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation.
N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing
industries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector
worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance
between the pathogenic bacteria’s virulence factor expression and their auto inducers, quorum quenching is a new effective
anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this
mainly include the following: (1) the inhibition of signal molecule biosynthesis, (2) blocking signal transduction, and (3)
chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling
aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination,
purification and identification of auto inducers in this paper. 相似文献
3.
我国海洋遥感应用的进展 总被引：1，自引：0，他引：1
刘宝银 《地球信息科学学报》2000,2(4):67-70
本文就我国20余年的海洋遥感应用历程,以三个阶段,4种类型信息源的分析及其相关手段和理论基础,按时间前后,着重阐述了所取得的成果,并展示我国海洋遥感技术未来发展的机遇与挑战. 相似文献
4.
Quorum sensing(QS)disruption is considered as a potential alternative strategy to combat bacterial diseases in aquaculture.In this study,we isolated and identified bacteria degrading QS molecules from pond sediment and fish intestine.A total of 132 strains were obtained in the enrichment culture,of which two strains were identified as Enterobacter sp.f003 and Staphylococcus sp.sw120,being isolated from the fish intestine and pond sediment,respectively.We found that strains f003 and sw120 could degrade acyl-homoserine lactones(AHLs)and cause no hemolysis of sheep red blood cells.The AHL lactonase(aiiA)homologous gene in the two strains was detected in PCR amplification and the high-degrading activity to N-hexanoyl-L-homoserine lactone(C6-HSL)and AHLs secreted from pathogenic Aeromonas hydrophila was assessed.Meanwhile,the artificial infection of cyprinid Carassius auratus gibelio with intraperitoneal injection showed that the two strains were avirulent.Therefore,the obtained indigenous bacteria are candidate probiotics against pathogenic A.hydrophila in aquaculture. 相似文献
5.
Pathogenicity of vibrios in fish: An overview 总被引：1，自引：0，他引：1
Norman Y.S.Woo 《中国海洋大学学报(英文版)》2003,2(2):117-128
Bacteria of the genus Vibrio are ubiquitously distributed in the marine environment. Due to the rapid expansion of intensive mariculture and the consequent deterioration of culture conditions, more and more Vibrio spp. have been recognized as pathogenic agents in outbreaks of vibriosis, a serious epizootic disease affecting most wild and farmed fish species worldwide, which has become the most important limiting factor for the development of intensive mariculture industry. Attempts have been made to understand the pathogenicity of vibrios in host fish with the ultimate aim of elucidating the best means for disease control. After an extensive literature survey of the recent advances in the field of fish vibriosis, the pathological changes, virulence factors and associated potential pathogenic mechanisms, transmission routes and related environmental factors involved in outbreak of vibriosis, as well as the controlling strategies are reviewed in the present paper. 相似文献
6.
方红亮 《地球信息科学学报》2021,23(7):1155-1168
尺度效应是地球科学和定量遥感中的重要研究课题,目前的许多研究大多集中在估算尺度效应带来的误差,而对一些关键的植被结构参数是否存在尺度效应及其尺度转换方法尚存在诸多不同见解。本文针对真实和有效叶面积指数（Leaf Area Index, LAI和Effective LAI, LAIe）以及聚集指数（Clumping Index, CI）3个植被关键结构参数,从基本概念和获取方法上分析参数的尺度效应及其尺度转换方法。从定义上看,LAI并不存在尺度效应,而LAIe和CI则存在尺度效应,其中CI的尺度效应由LAIe引入（CI=LAIe/LAI）。在野外实测中,LAI破坏测量法没有尺度效应,但由孔隙率模型获取3个参数的方法均具有尺度效应。异速生长方程和遥感反演方法的尺度效应取决于方法本身的线性或非线性特征。目前全球主要的LAI、LAIe和CI遥感产品都基于非线性模型获取,其反演过程具有尺度效应。像元尺度的LAI本身并不具有尺度效应,而像元尺度的LAIe和CI虽然具有尺度效应,但在实践中常常被忽略。因此,实际工作中应注意区分参数概念本身、野外测量、遥感反演方法以及遥感产品等所展示的不同尺度效应。 相似文献
7.
准实时监测城市发展、掌握城市土地利用类型是日趋科学化、合理化进行城市规划的基本要求。随着信息通信技术、移动互联网技术、位置服务等的发展,海量的手机数据、浮动车数据、公交卡数据、社交网络数据等在内的人类时空活动信息为从“人”的角度动态实时感知城市土地利用、空间结构提供了可能。本文以深圳市为例,基于百万名QQ用户2013年的电子足迹数据,提出了不同类型的人类时空活动指数,以建立人类活动与城市地物间的对应关系;借鉴遥感影像不同波段记录各类地物在特定波谱区间辐射值的思想,生成各类人类时空活动指数波段图;并利用最大似然法对该“类高光谱影像”进行城市土地监督分类,获取城市的土地利用图。通过与深圳市规划图的对比验证,全体分类精度为72%。相较于传统基于“物”的遥感探测手段,基于“人”的城市感知更能反映城市内部相同地类的发展差异性。 相似文献
8.
Microbial communities play key roles in the marine ecosystem. Despite a few studies on marine microbial communities in deep straits, ecological associations among microbial communities in the sediments of shallow straits have not been fully investigated. The Bohai Strait in northern China(average depth less than 20 m) separates the Bohai Sea from the Yellow Sea and has organic-rich sediments. In this study, in the summer of 2014, six stations across the strait were selected to explore the taxonomic composition of microbial communities and their ecological associations. The four most abundant classes were Gammaproteobacteria, Deltaproteobacteria, Bacilli and Flavobacteriia. Temperature, total carbon, depth, nitrate, fishery breeding and cold water masses influenced the microbial communities, as suggested by representational dif ference and composition analyses. Network analysis of microbial associations revealed that key families included Flavobacteriaceae, Pirellulaceae and Piscirickettsiaceae. Our findings suggest that the families with high phylogenetic diversity are key populations in the microbial association network that ensure the stability of microbial ecosystems. Our study contributes to a better understanding of microbial ecology in complex hydrological environments. 相似文献
9.
【目的】研究海洋土曲霉C23-3与不同类型海洋微生物共培养对其次生代谢产物的影响,挖掘土曲霉菌株C23-3的次生代谢潜力。【方法】将副溶血弧菌、枯草芽孢杆菌和胶红酵母的活菌或灭活菌体分别以不同时间与土曲霉C23-3共培养;采用DPPH自由基清除法和Ellman法分别评价各提取物的抗氧化和乙酰胆碱酯酶抑制活性,采用滤纸片法比较各提取物的抗菌活性,采用HPLC指纹图谱分析各提取物化学成分的差异。【结果与结论】发现不同类型的微生物与土曲霉共培养均可激活一些原本沉默的活性次级代谢产物;菌株及共培养物的化学拮抗能力、HPLC指纹图谱中的特征代谢产物变化揭示在活菌培养体系中土曲霉占竞争优势;而且灭活菌体中可能存在某些信号物质,在12 d时对土曲霉群体自感应信号分子丁内酯-I的产生具有比活菌更强的刺激作用。研究结果为深入挖掘海洋真菌代谢潜力及抗老年痴呆等活性先导化合物的发现提供基础。 相似文献
10.
多元指标的海上溢油信息提取 总被引：1，自引：0，他引：1
海上溢油给海洋生态环境带来了巨大的影响,甚至需要几十年才能恢复。运用卫星遥感进行海上溢油监测已成为目前溢油监测的主要手段。本文对海上溢油遥感监测方法进行了分析,鉴此,提出了一种SAR数据的多元指标溢油信息提取方法。首先,对图像进行分割,然后,建立溢油形状参数、纹理特征指数、物理特性指数等主要指标,并以层次分析法得出每一类指标的权重。针对每一类指标,以经现场验证的溢油图像为基础,选择形状参数,如周长与面积比值、复杂度等,建立溢油形状判读等级;选择纹理特征参数,以灰度共生矩阵的相关性、熵、变化等来表达溢油的纹理特性,建立溢油纹理特征判断等级;选择溢油物理特征,如溢油与海水的标准差、均方根差、对比度等,建立溢油物理参数判断等级。在此基础上,建立海上溢油遥感信息提取指数,计算分割图斑的溢油遥感信息提取指数,以此判断溢油遥感信息提取的置信度,为溢油识别提供依据。 相似文献
11.
海洋功能区划管理信息系统 总被引：5，自引：0，他引：5
海洋开发利用和保护已成为全球的热点。如何合理地利用海洋资源是未来社会经济可持续发展的重大问题。海洋功能区划是为实现海洋资源、社会经济可持续发展的重要举措。海洋功能区划管理信息系统是在地理信息系统的支持下,以海洋功能区划数据、基础地理数据和遥感数据为地理实体对象,集知识、分析、决策和服务为一体的系统。该系统从应用角度为空间数据管理和信息共享提供了一种可行的解决方案。本文以福建省海洋功能区划管理信息系统的建设为例,对系统的总体结构、功能、数据库和系统集成等方面进行了探讨。 相似文献
12.
Flavobacterium columnare, the etiological agent of columnaris disease, is one of the most important and widespread bacterial pathogens of freshwater fish. In this study, we constructed two artificial selectable markers (chloramphenicol and spectinomycin resistance) for gene transfer in F. columnare. These two new artificial selectable markers, which were created by placing the chloramphenicol or spectinomycin resistance gene under the control of the native acs regulatory region of F. columnare, were functional in both F. columnare and Escherichia coli. The integrative/conjugative plasmids constructed by using these markers were introduced into F. columnare G4 via electroporation or conjugation. The integrated plasmid DNA was confirmed by Southern blotting and PCR analysis. These two markers can be employed in future investigations into gene deletion and the pathogenicity of virulence factors in F. columnare. 相似文献
13.
海量遥感图像的检索与管理,需要研究有效的基于内容的图像检索方法。目前,对遥感图像的CBIR研究,主要集中在颜色、纹理、形状等视觉特征检索方法上,尚缺乏实用系统。从面向实用的遥感图像检索系统(RSIQuery) 的体系架构设计入手,着重分析了CBIR遥感图像数据模型和数据组织方式,并给出了系统的初步实现。 相似文献
14.
Exopolysaccharides from marine bacteria 总被引：1，自引：0，他引：1
CHIZhenming FANGYan 《中国海洋大学学报(英文版)》2005,4(1):67-74
Microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives, textiles, pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and industrial waste treatments, etc. This paper gives a brief summary of the information about the EPSs produced by marine bacteria, including their chemical compositions, properties and structures, together with their potential applications in industry. 相似文献
15.
及时准确掌握农作物种植制度时空分布信息,对于确保国家粮食安全与农业结构合理具有重要意义。随着时序遥感影像质量的不断提高,基于时序遥感数据的农作物种植制度研究备受关注。本文从研究框架、遥感特征参数以及数据产品等角度,分析了基于时序遥感数据的农作物种植制度最新研究进展。研究发现:① 前农作物种植制度研究框架,主要包括耕地复种指数和农作物制图等相关内容,其问题在于需要高质量耕地分布数据支撑以及易将热带亚热带湿润区撂荒地误判为农作物等;② 于红边和短波红外的新型多维度光谱指数,有助于更好地揭示农作物生长发育过程,大尺度农作物时序遥感制图取得了系列研究成果,但需要应对不同作物光谱差异细微、同种作物在不同区域和年份存在明显类内异质性的挑战;③ 尺度中高分辨率耕地复种指数产品不断丰富,但其时效性和时空连续性有待加强;④ 欧美少数国家外,目前农作物分布数据产品覆盖的作物类型有限,我国大尺度农作物种植制度数据产品欠缺,特别是复杂多熟制农业区。随着多源遥感数据时空谱分辨率的不断提高以及云计算平台性能的不断发展,我们对以下方面进行了研究展望:① 新研究框架,建立直接提取耕作区、农作物种植模式的农作物种植制度一体化遥感监测技术框架;② 一步加强新型多维度遥感指数及其物候特征指标设计,拓展农作物种植制度监测的遥感特征参数;③ 立作物种植制度变化遥感监测技术,实现多年信息连续自动提取。 相似文献
16.
国内流域产汇流模型与应用分析 总被引：1，自引：0，他引：1
本文对国内流域产汇流研究与应用进行了分析、比较和综述。重点是对流域产流模型结构建立的理论基础分析,流域汇流的单位线方法和流域的实际物理特性和水流运动的内部机制之间的对应关系的分析。流域产汇流模型和遥感技术相结合应用到具体工程实践所产生的新的理论技术和研究方向作了分析。最后应用系统论、控制论和反问题对上述问题进行了系统的归纳和总结。 相似文献
17.
基于遥感长时间序列的分析能够得到更加科学、完整、全面的特征规律,本文以黄河三角洲为研究区域,开展了生态指数遥感估算及分析研究。基于Google Earth Engine (GEE)分析了2000年以来逐年度归一化植被指数（NDVI）、湿度指数（Wet）、盐分指数（SI3）、遥感生态指数（RSEI）,获得了完整、细致长时间序列的分析结果。考虑到黄河三角洲的区域特点,引入了盐分指数（SI3）与遥感生态指数（RSEI）相结合的评价分析方法。研究发现,自2011年以来研究区的生态环境指数呈上升趋势,生态环境持续改善。 相似文献
18.
三维虚拟地球的海洋信息适用性分析及原型研究 总被引：2，自引：0，他引：2
分析了三维虚拟地球在海洋应用上具有的优势及可能面临的挑战的基础上,首次提出了一种结合网格、语义网等前沿技术和理念,利用三维虚拟地球实现三维虚拟海洋的技术方案;并按照SOA的多层次架构,采用XML的多源异构海洋环境数据快速交换、海洋环境信息服务快速封装与发布、海洋环境信息服务虚拟组织、远程可视化等关键技术,实现了海洋环境信息网格平台及网格前端门户系统--三维虚拟海样(VRMarine)。VRMarine不仅能够集成网格环境下多源海洋环境信息服务,再现逼真的三维海洋环境场景,同时,还支持对功能服务的动态集成,实现多维时空特征分析。研究表明,该方案是切实可行和有效的,对三维虚拟海洋具有一定的现实及指导意义。 相似文献
19.
Response of microbial community to petroleum stress and phosphate dosage in sediments of Jiaozhou Bay,China 总被引：1，自引：0，他引：1
ZHAO Yangguo CHEN Min BAI Jie LI Xinwei Farhana Zulfiqar and WANG Qianli 《中国海洋大学学报(英文版)》2014,13(2):249-256
The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sediment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollution and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel electrophoresis (DGGE) techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually enhanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and consequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation. 相似文献
20.
云、雾、雨往往导致获取同步观测陆面-大气或海面-大气的遥感数据的复杂性,使得多圈层探测的遥感数据缺乏连续性、实时性、准确性和可用性。所以,多云、多雨环境一直成为遥感对陆面和海面探测与研究的瓶颈。对我国来说,只有实现在多云、多雨地区的全天候、全天时地对地观测,我国的遥感应用才能形成一个较为完整的体系。我们提出了多云、多雨地区遥感这个概念,介绍这方面的研究进展。为解决这一瓶颈问题,通过多云、多雨环境下对地观测系统数据获取与信息处理的多学科研究,提出发展适用于多云、多雨环境的对地观测系统的科学思路与方案。 相似文献