A role for Toll-like receptor 4 in the host response to the lung infection of Yersinia pseudotuberculosis in mice

Although a Yersinia pseudotuberculosis (Yptb) lung infection model has been developed to study Y. pestis pathogenesis, it is still necessary to establish a new animal model to mimic the pathophysiological features induced by Y. pestis infection. Here, we provide a new lung infection model using the Yptb strain, IP2777, which displayed rapid spread of bacteria to the liver, spleen, and blood. In addition, we examined whether TLR4 is involved in Yptb-induced pathogenesis in the lung infection model of mice we generated. Following lung infection of WT and TLR4-deficient mice with the Yptb strain IP2777, the survival rate, bacterial colonization, histopathology, and level of cytokines and chemokines in the lung, spleen, liver, and blood were analyzed. TLR4-deficient mice had a lower survival rate than WT mice in response to Yptb lung infection. Although the bacterial colonization and pathology of the lung were comparable between WT and TLR4-deficient mice, those of the spleen and liver were more severe in TLR4-deficient mice. In addition, the levels of TNF-α and CXCL2 in the liver and IL-6 and CXCL2 in the blood were higher in TLR4-deficient mice than in WT mice. Our results demonstrate that TLR4 is necessary for optimal host protection against Yptb lung infection and TLR4-deficient mice may serve as a better genetic model of Yptb infection for mimicking Y. pestis infection.     

The origin,evolution, cultivation,dissemination, and diversification of Asian and African rices

Summary Available evidences drawn from biosystematics, evolutionary biology, biogeography, archaeology, history, anthropology, paleo-geology and paleo-meteorology are pooled to reconstruct the series of events that led to the cosmopolitan cultivation of the Asian cultivated rice (O. sativa) and the regionalized planting of the African cultigen (O. glaberrima) in West Africa. The genus Oryza originated in the Gondwanaland continents and, following the fracture of the supercontinent, became widely distributed in the humid tropics of Africa, South America, South and Southeast Asia, and Oceania. The two cultivated species have had a common progenitor in the distant past. Parallel and independent evolutionary processes occurred in Africa and in Asia, following the sequence of: wild perennialwild annualcultivated annual. The weed races also contributed to the differentiation of the cultivated annuals. The corresponding members of the above series are O. longistaminata Chev. et Roehr., O. barthii A. Chev., O. glaberrima Steud., and the stapfii forms of O. glaberrima in Africa; O. rufipogon Griff., O. nivara Sharma et Shastry, O. sativa L., and the spontanea forms of O. sativa in Asia.The differentiation and diversification of the annuals in South Asia were accelerated by marked climatic changes following the last glacial age, dispersal of plants over latitude or altitude, human selection, and manipulation of the cultural environment.Cultivation of rice began in many parts of South and Southeast Asia, probably first in Ancient India. Cultural techniques such as puddling and transplanting were first developed in north and central China and later transmitted to Southeast Asia. Wetland culture preceded dryland culture in China, but in hilly areas of Southeast Asia, dryland cultivation is older than lowland culture. The planting method progressed from shifting cultivation to direct sowing in permanent fields, then to transplanting in bunded fields.Widespread dispersal of the Asian cultigen led to the formation of three eco-geographic races (Indica. Sinica or Japonica, and Javanica) and distinct cultural types in monsoon Asia (upland, lowland, and deep water). Varietal types changed readily within the span of a millenium, largely due to cultivators' preferences, socio-religious traditions, and population pressure. Genetic differentiation developed parallel to the ecologic diversification process.The African cultigen developed later than the Asian cultigen and has undergone less diversification. The wild races in South America and Oceania retain their primitive features mainly due to lack of cultivation pressure or dispersal.Both the African and Asian rices are still undergoing evolutionary changes at habitats where the wild, weed, and cultivated races co-exist.     

农机推广培训工作中存在的问题及解决措施

农机推广培训是农机工作的重要环节,但目前依然存在农机购置补贴政策实施滞后、农机产品供货不及时、农机购置补贴范围不宽、农机培训内容单一以及部分农机具定价偏高、适用性不强等问题,为此,提出牢固树立为农民服务的意识、合理分配农机化投入资金、建设高素质农机科技队伍、简化办事程序等工作措施,以促进农机推广培训工作的有效开展。     

基于文献计量的抗生素耐药基因(ARGs)传播研究现状及热点分析

为了了解抗生素耐药基因传播研究的整体状况和前沿动态,以WebofScience核心合集数据库集为基础,对20082017年间全球范围内有关该研究领域的文献报道开展计量学分析,从总体情况、研究力量、研究热点等方面进行系统评价。结果表明,10年间有关该领域的研究报道增加显著,自2008年的341篇增加到2017年的1011篇,增加196%。国内学者发文量自2008年的15篇增加到2017年的210篇,文献增长趋势显著高于国外。通过对作者分析表明,主要研究力量持续增加,主要高产作者(第一作者和通讯作者)后5年比前5年发文量增加。通过对论文关键词计量分析表明,四环素是目前关于抗生素耐药基因传播研究热点抗生素,废水则是热点研究基质。研究较多的耐药菌包括鲍曼不动杆菌、肺炎克雷伯菌、大肠杆菌、金黄色葡萄球菌、耐甲氧西林金黄色葡萄球菌、沙门菌、铜绿假单胞菌等,其耐药机制主要涉及β-内酰胺酶、超广谱β-内酰胺酶以及碳青霉烯酶类耐药基因。具体研究内容主要有多重耐药、致病性、流行病学、整合子、共转移、质粒、生物膜、演化、基因水平转移、可移动基因元件等。综合文献计量分析结果,抗生素耐药基因传播仍然是抗生素耐药研究领域的研究热点,在未来的研究发展趋势方面,质粒在抗生素耐药基因传播中所扮演的角色、抗生素耐药性的起源与演化等方向将具有特定的研究价值和发展空间。     

Seasonal patterns of dispersal of ascospores of Cryphonectria parasitica (chestnut blight)

Infected barks of chestnut blight cankers, caused by Cryphonectria parasitica , were collected from a naturally infected orchard and incubated at different temperatures. Cankers started to discharge ascospores about a week after incubation at 15–25°C; most ascospores were collected at 20 and 25°C. When incubated at 5, 10 or 30°C, only a few cankers released a small number of ascospores and only during the later stages of incubation. However, the rate of formation of perithecia was not affected by the incubation temperature. The number of airborne ascospores was monitored using a volumetric spore trap in a chestnut orchard during 1996 and 1997. In both years, the number of ascospores trapped daily varied greatly, but in general it increased sharply from March onwards, reached a peak in May, and then declined steeply. There was a significant correlation between daily counts of ascospores and air temperature. Time-series transfer function (TF) analysis showed a positive association of the daily number of ascospores with increasing temperature, rain events and wet/humid conditions. In general, values predicted by the TF model agreed well with the observed pattern. However, a multiple regression equation based on TF analysis failed to provide a satisfactory prediction of the daily number of ascospores.     

Web2．0在农业信息传播中的应用

介绍了Web2．0及其在农业信息传播中的应用与可行性,指出Web2．0在农业信息传播中的特点。     

论数字参考咨询服务中利用镜像站点进行原文传递的侵权问题

就数字参考咨询服务中利用镜像站点进行原文传递的侵权问题进行了探讨,提出了利用镜像站点进行原文传递对数据提供商的权益侵害和对著作权人的信息网络传播权侵犯的观点。     

干旱地区土壤保墒增墒的有效措施

旱灾是制约辽西地区农业发展的重要因素。针对辽西干旱地区农业生产实际,介绍深松和坐水播种技术及其作用,并通过应用试验以验证其对土壤的保墒增墒效果。试验结果表明,在干旱条件下采用这两种技术可有效改善土壤情况,为种子发芽出苗创造适宜的环境条件。