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1.
本研究比较了饲料中添加粪肠球菌(Enterococcus faecalis LYB1)、嗜酸乳杆菌(Lactobacillus acidophilus W2)和凝结芽孢杆菌(Bacillus coagulans NJ17)对凡纳滨对虾(Litopenaeus vannamei)幼虾的生长、抗病力及肠道菌群结构的影响。以基础饲料中分别添加1.0×1010 cfu/kg浓度的3种不同乳酸菌为实验组,以基础饲料为对照组,以投喂方式养殖对虾42 d。养殖结束后,进行14 d的副溶血弧菌(Vibrio parahaemolyticus)攻毒实验。研究表明:投喂3种乳酸菌的实验组对虾的体重、特定生长率、饲料效率和表观消化率均显著高于对照组(P<0.05),其中以添加凝结芽孢杆菌组效果最佳。攻毒实验显示,添加粪肠球菌和嗜酸乳杆菌均可显著降低对虾的累计死亡率(P<0.05)。添加乳酸菌的各实验组对虾的肠道细菌群落结构与对照组相比均发生了明显变化,其中以添加粪肠球菌组差异最大。在门水平上,变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)为对虾肠道优势菌群。在纲分类水平上,α-变形菌纲(Alphaproteobacteria)、丹毒丝菌纲(Erysipelotrichia)和黄杆菌纲(Flavobacteriia)为对虾肠道优势菌群。研究结果显示,凝结芽孢杆菌NJ17对凡纳滨对虾促长效果最佳,而嗜酸乳杆菌W2对对虾抗病力提高效果最佳,3种乳酸菌均明显改善了对虾肠道微生物群落的组成和丰度。  相似文献   
2.
海带苗绿烂病暴发严重威胁海带养殖生产,给海带养殖业造成巨大经济损失。研究发现,海带中的多酚化合物可以抵御海带病害初期病原体侵入。为研究多酚对绿烂海带表面附生菌的抑菌效果,在病烂部位分离出一株细菌,通过16s rRNA基因测序的方法,证实该细菌为小孔芽孢杆菌(Bacillus foraminis)。进一步以健康海带为原料提取多酚,利用平板生长抑制法,以哈维氏弧菌(Vibrio harveyi)和溶藻弧菌(Vibrioalginolyticus)作为对照,分析多酚对小孔芽胞杆菌的抑菌效果。结果显示褐藻多酚在接种了哈维氏弧菌和溶藻弧菌的培养基上产生了不同大小的抑菌圈,而在接种有小孔芽孢杆菌的培养基上未产生抑菌圈,表明多酚对小孔芽胞杆菌无抑菌效应。此项研究为海带多酚抑菌作用提供了参考,同时对了解海带病害暴发及开展海带病害防治工作具有重要意义。  相似文献   
3.
西藏林周县是我国大骨节病(KBD)患病较为严重的地区之一,本文将林周县作为研究区,通过使用地理探测器(GeoDetector)量化分析KBD患病率风险因子的影响,并使用环境化学方法验证空间分析结果。通过对10个潜在影响因子的分析以及对当地KBD患病村和非患病村的土壤-水-粮食-人这一生物地球化学循环的环境化学分析,结果表明:(1)林周县KBD由一组多重且交互作用的环境影响因子共同作用影响,其中最重要的控制因子是地层因子;(2)所有环境介质(土壤、水、谷物)及人体组织中的硒元素浓度在KBD患病区均低于非患病区;(3)当地居民对硒和铬的摄入严重不足,尤其是KBD患病村中居民硒元素平均日摄入量(ADD)大约仅为世界卫生组织(WHO)建议的成人基本摄入量下限的4%;(4)我们推测,当地居民患病主要是由于地层这一影响因子,这是由于通过生态系统的迁移转化导致当地人口严重硒缺乏,最终导致地方性生物地球化学硒缺乏。  相似文献   
4.
赵亚波  王智 《测绘通报》2020,(8):160-163
错台是地铁隧道的主要病害之一,通常是由于盾构机施工控制不好或是隧道荷载发生变化导致,错台的发生也会引起隧道收敛变形及渗水等其他病害。传统手段主要采用人工巡检等方式进行错台情况的检测,由于受夜间窗口期短的影响,该方法效率低,成果难以精确量化。研究采用基于轨道的隧道移动三维激光扫描系统对隧道错台进行检测,通过快速获取隧道三维点云生成正射影像,并基于正射影像进行管片的划分及里程的匹配,进而根据每一环的三维点云信息计算管片错台情况。以青岛地铁2号线为例,本文介绍了移动扫描技术在地铁隧道管片错台检测的应用情况,为该技术在其他隧道的推广应用提供了一定的借鉴意义。  相似文献   
5.
Impact of global change on transmission of human infectious diseases   总被引:1,自引:0,他引:1  
Global change,which refers to large-scale changes in the earth system and human society,has been changing the outbreak and transmission mode of many infectious diseases.Climate change affects infectious diseases directly and indirectly.Meteorological factors including temperature,precipitation,humidity and radiation influence infectious disease by modulating pathogen,host and transmission pathways.Meteorological disasters such as droughts and floods directly impact the outbreak and transmission of infectious diseases.Climate change indirectly impacts infectious diseases by altering the ecological system,including its underlying surface and vegetation distribution.In addition,anthropogenic activities are a driving force for climate change and an indirect forcing of infectious disease transmission.International travel and rural-urban migration are a root cause of infectious disease transmission.Rapid urbanization along with poor infrastructure and high disease risk in the rural-urban fringe has been changing the pattern of disease outbreaks and mortality.Land use changes,such as agricultural expansion and deforestation,have already changed the transmission of infectious disease.Accelerated air,road and rail transportation development may not only increase the transmission speed of outbreaks,but also enlarge the scope of transmission area.In addition,more frequent trade and other economic activities will also increase the potential risks of disease outbreaks and facilitate the spread of infectious diseases.  相似文献   
6.
Understanding the diverse ways that landscape connectivity influences the distribution of microbial species is central to managing the spread and persistence of numerous biological invasions. Here, we use geospatial analytics to examine the degree to which the hydrologic connectivity of landscapes influences the transport of passively dispersed microbes, using the invasive plant pathogen Phytophthora ramorum as a case study. Pathogen occurrence was analyzed at 280 stream baiting stations across a range of watersheds – exposed to variable inoculum pressure – in California over a 7-year period (2004–2010). Using logistic regression, we modeled the probability of pathogen occurrence at a baiting station based on nine environmental variables. We developed a novel geospatial approach to quantify the hydrologic connectivity of host vegetation and inoculum pressure derived from least cost distance analyses in each watershed. We also examined the influence of local environmental conditions within the immediate neighborhood of a baiting station. Over the course of the sampling period, the pathogen was detected at 67 baiting stations associated with coastal watersheds with mild climate conditions, steep slopes, and higher levels of inoculum pressure. At the watershed scale, hydrologic landscape connectivity was a key predictor of pathogen occurrence in streams after accounting for variation in climate and exposure to inoculum. This study illustrates a geospatial approach to modeling the degree to which hydrologic systems play a role in shaping landscape structures conducive for the transport of passively dispersed microbes in heterogeneous watersheds.  相似文献   
7.
Water management practices and access to safe water supplies have major implications for human health. While a range of assessments has been developed to assess water vulnerability, limited work has extended these concepts to health and wellbeing. Water-associated disease cycles are characterized by complex linkages between social and ecological determinants, thus conceptualizing vulnerability in the context of health offers a useful framework for analysis. This paper applies a water associated disease index (WADI) as a tool to deepen understanding of changing vulnerability to dengue, comparing conditions in 2000 and 2010 in Pernambuco, Northeast Brazil. Multi-dimensional data were integrated into indicators of exposure and susceptibility using the WADI approach, including water access, land cover, climate, and solid waste collection, and outputs were validated and visualized in map form. The findings illustrate heterogeneous patterns of vulnerability to dengue in the region, and highlight trends of seasonal and long-term changes. Highest vulnerability was observed in densely populated Recife and the surrounding coastal region in both time periods, with climate conditions creating seasonal trends in exposure to dengue. While more remote areas in the semi-arid Sertão showed low vulnerability overall, increases were observed in some areas between 2000 and 2010 due to land use intensification and growing population densities. These findings suggest that interventions should consider the dynamic nature of social and ecological factors that contribute to health outcomes and address current as well as future populations vulnerable to dengue transmission. This vulnerability mapping approach can be applied to other water-associated diseases impacted by global environmental change to highlight priority areas for further investigation and contribute towards improving interventions.  相似文献   
8.
词频反文档频率是文档特征权值表示的常用方法,用以评估单词对于语料库中的其中一份文件的重要程度。通过合理映射病例库与语料库的词汇关系,对词频反文档频率模型进行改进,并将改进后的词频反文档频率模型应用到针灸处方疾病症状权重挖掘中,计算出疾病所对应的各种症状权重。实验统计了106种疾病,其中与临床诊疗经验相符合的有84种,准确率达79.2%,实验表明改进的模型能得到较好的疾病症状权重鉴别效果。  相似文献   
9.
目的:探讨多房囊性肾细胞癌(MCRCC)的256层iCT增强扫描影像特征。方法:搜集6例经外科手术病理证实为多房囊性肾细胞癌患者的临床资料、CT影像资料及病理资料,对比分析多房囊性肾细胞癌的影像特点。结果:6例均发生于肾实质区,增强扫描可见不同程度囊性改变、无明显壁结节、有包膜边界清晰、肾盂肾盏无侵蚀破坏,无肾静脉癌栓形成,均无远处转移征象,3例行患侧肾全切除术,3例行肾肿瘤楔形切除术。结论:多房囊性肾细胞癌的256层iCT增强扫描表现有一定特征性,可作为术前诊断的理想手段,对治疗方案的优选及改善患者生存质量有积极意义。  相似文献   
10.
目的:探讨肾上皮样血管平滑肌脂肪瘤(EAML)的影像学特征及病理学特点,提高对该疾病的认识。材料和方法:回顾性分析2008年1月至2014年4月间本院7例经手术病理证实为肾脏EAML的影像学表现及病理特点。结果:7个病例8个病灶,其中5个病灶部分突出肾轮廓外,2个病灶突入肾窦,1个病灶同时突出肾轮廓外及肾窦;CT平扫3例呈稍高密度,2例呈等密度,1例MRI呈稍长T1短T2;增强扫描2例病灶呈"快进快出",2例呈"快进慢出";5例见"皮质掀起征",5例见"黑星征",其中4例同时出现"皮质掀起征"及"黑星征";2例病理有恶性表现。组织学表现:肿瘤主要由上皮样细胞、平滑肌、厚壁血管及脂肪组成。免疫组化:常表达肿瘤细胞S-100、瘤细胞Vim、HMB-45、HHF-35及CD34。结论:肾上皮样血管平滑肌脂肪瘤的影像学表现多样化,影像学表现难与其他疾病相鉴别,当肿瘤部分突出肾轮廓外或向肾窦内生长,CT平扫密度呈稍高或等密度应考虑有EAML可能。  相似文献   
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