猪TLR5基因表达水平与F18大肠杆菌侵染关系分析

为了探究猪Toll样受体（Toll-like receptor 5,TLR5） 基因表达水平与F18大肠杆菌抗性的关系,试验通过不同血清型产肠毒素大肠杆菌（F18ab和F18ac）侵染猪小肠上皮细胞（IPEC-J2）,同时通过脂多糖（LPS）分别诱导IPEC-J2细胞4和8 h,利用实时荧光定量PCR检测TLR5基因表达水平变化,并利用Western blotting进行蛋白表达分析。结果显示,不同血清型大肠杆菌（F18ab和F18ac）菌体侵染IPEC-J2细胞后,TLR5基因表达水平均极显著上调（P<0.01）;LPS诱导IPEC-J2细胞4和8 h后,TLR5基因表达水平均极显著上调（P<0.01）,且在LPS诱导IPEC-J2细胞8 h后,TLR5基因表达水平明显高于诱导4 h。与对照组相比,细胞中TLR5蛋白的表达水平极显著上调（P<0.01）,与LPS诱导及F18大肠杆菌菌体刺激IPEC-J2细胞后mRNA表达水平结果相一致。本研究在细胞水平上分析了TLR5表达水平和F18大肠杆菌侵染的相关性,进一步证实猪TLR5基因的表达水平在细胞抵抗F18大肠杆菌的侵染过程中发挥了重要的调控作用,为今后关于TLR5基因功能及其在大肠杆菌腹泻遗传育种应用的研究奠定基础。     

Weed or not a weed? Density,perceptions and management of Chromolaena odorata (Asteraceae) in West Africa: Voices from Ghana

The status (weed or beneficial shrub) of Chromolaena odorata in West Africa has been a major subject of debate since its introduction in the 1930s. Its negative impacts on agriculture and biodiversity are clear. However, indigenous people have harnessed several benefits of the plant, making management strategies less straightforward. Using indigenous voices in Ghana, the current perceptions of C. odorata in West Africa were assessed. Here, 90 respondents in three regions of Ghana were interviewed, using questionnaires, on aspects relating to the abundance, perceptions and management of C. odorata in their communities. Overall, results showed that the density of C. odorata had declined. The majority of the respondents considered C. odorata as a fallow shrub, a medicinal plant or both. However, impacts on crop production and injuries incurred during physical control were also highlighted. The local uses of the plant in Ghana included treating fevers and injuries, and as a fallow shrub for soil nutrient replenishment. Although most of the respondents classified C. odorata as a useful shrub in Ghana, they also highlighted the use of local farming tools such as cutlasses for the slash of the plant. The use of herbicides for the control of C. odorata was rare and not applied specifically for C. odorata. In conclusion, local awareness programmes on the deleterious impacts of C. odorata on ecosystem functioning and livelihoods are required for its effective management in West Africa.     

Comparative analysis of genetic structures and aggressiveness of Fusarium pseudograminearum populations from two surveys undertaken in 2008 and 2015 at two sites in the wheat belt of Western Australia

Fusarium crown rot (FCR), caused predominantly by Fusarium pseudograminearum (Fp) in Australia, is an important fungal disease of wheat and barley. FCR causes significant yield losses and reduced grain quality worldwide. This study investigated the population dynamics of FCR-causing F. pseudograminearum isolates from Western Australia (WA), a major wheat-growing region. Wheat samples were collected from a total of seven different sites in 2008 and 2015. Two sites, Tammin and Karlgarin, with moderate to high FCR incidence, were intensively sampled in both years. The results revealed significant increase in Fp isolation frequency between 2008 and 2015. Over 86% of 1100 Fusarium isolates were Fp in 2015 compared with 59% of 639 isolates from 2008. Mating type idiomorphs, toxin chemotypes and population genetic structures were determined for a subset of 279 Fp isolates (132 isolates from 2008 and 165 from 2015). Mating type analysis revealed differences in MAT1-1 and MAT1-2 distributions between Tammin and Karlgarin for both years. Results also showed that 97.6% of Fp isolates analysed had the 3-ADON trichothecene chemotype. Additionally, for the first time in Australia, the 15-ADON chemotype was identified in 2.3% and 2.4% of Fp isolates from 2008 and 2015, respectively. The genetic structure of Fp population determined using 21 cleaved amplified polymorphic sequence (CAPS) markers revealed a high level of genetic variation within and between populations. In addition, 2015 isolates from Tammin and Karlgarin were significantly more aggressive (P < 0.0001) than 2008 isolates. This finding may have implications in managing this significant fungal disease.     

Uncertainty and investment in precision agriculture – Is it worth the money?

Irreversibility and uncertainty render the standard capital budgeting techniques such as net present value (NPV) analysis insufficient as a decision criterion. The standard NPV underestimates the value of the investment by not including the value of waiting for new information to reduce the uncertainty of the cashflows generated by the investment. An alternative to NPV analysis is real options. In this study, we apply real options analysis to an investment decision for a grain producer in Western Australia. The investment choice is to either purchase machinery suitable for undertaking controlled traffic precision agriculture or acquire a conventional system and reduce sowing time. The results of the analysis suggest that the required rates of return for the two investment alternatives need to be approximately 96–156% higher than the rates of return used in the standard NPV analysis. These higher rates of return are required to compensate for the uncertainty inherent in the cropping systems of the farm. Also, in most cases, even though the variable costs of operating the precision agriculture system were higher, due to smaller operating widths, the additional returns generated by managing zones individually outweighed these additional costs. Further analysis also shows that the relative size of management zones has a marked effect on the returns generated and that it is possible to increase returns by taking out marginally productive zones.     

学生对问题导向性教学模式的认可及影响因素——以“资源与环境经济学”教学为例

问题导向性教学模式被广泛应用在高校课程教学中，但是其教学效果很大程度上取决于学生对该教学模式的认可程度。以“资源与环境经济学”课程为例，运用经济学研究方法分析学生对问题导向性教学模式的认可程度以及影响因素。研究发现，多数学生赞同问题导向性教学模式，关注实际问题分析的学生更容易接受问题导向性教学模式。建议将问题导向性教学模式与传统教学模式相结合来提升总体教学效果。     

Effect of Tetranychus urticae (Acari: Tetranychidae) on yield,quality, and economics of tomato production

The twospotted spider mite, Tetranychus urticae Koch, is an important and consistent pest of vegetables in central and western North Carolina, particularly on tomatoes, Solanum lycopersicum L. Small plot experiments were conducted in 2007, 2008 and 2009 in which acaricides were applied to early and late-planted staked tomatoes based on threshold levels ranging from 0 to 50 mites per leaflet, with a non-treated control included. Vine ripe fruit were harvested at weekly intervals from all plots, and fruit were weighed and graded for size and quality. A partial budget analysis was conducted to compare net profitability among treatments. Results from 2007 to 2008 showed that total and marketable yield was higher in plots with low versus high densities of T. urticae, and that yield differences were mostly due to number of fruit harvested rather than size of fruit. In 2009 there were no differences in yields among treatments. Gold fleck caused by T. urticae feeding directly on the fruit was another factor that influenced marketability, with more fruit affected and a higher percentage of surface area affected in higher densities versus lower densities of T. urticae. Net profitability varied considerably among planting dates and years, but an action threshold level to avoid yield losses by T. urticae injury on staked tomatoes appeared to be about eight mites per leaflet on a second or third recently expanded leaf.     

西部原油管道余热回收系统的设计与应用

西部原油管道冬季运行油品热处理外输出站温度达到50-55℃，不但损伤管道防腐层，而且造成能源浪费。为此，对乌鲁木齐首站、鄯善站原油加热系统进行余热回收技术改造，在热媒换热器的基础上增加了油油换热器，使热原油与进站冷油进行热量交换，对综合热处理后的原油进行余热回收，既满足了原油综合热处理65℃的温度要求和40℃出站的温度要求，又达到节能降耗的目的，实际节约能源近30％。同时，冬季运行投用余热回收装置后，可防止紧急停输再启输工况下输油泵因油温过高保护停泵及部分冷油进入下游，并满足急冷热处理后的外输条件。（图7，表6，参8）     

西文图书回溯建库工作的实践研究——以内蒙古农业大学图书馆为例

结合内蒙古农业大学图书馆回溯建库工作实践,介绍回溯建库全过程。建库前做的准备工作有图书加工、确定建库依据、规定著录细则、培训编目人员等,提出套录数据、原编数据以及多卷书著录的具体实施方案。最后笔者对西文图书回溯建库中遇到的问题提出几点思考。     

西部地区农业技术推广工作存在的问题及对策

文章阐述了当前西部农业技术推广工作中存在的问题,结合实际提出加强西部农技推广工作的建议与对策,对促进西部农技推广工作的开展具有一定的借鉴意义。     

Anthelmintic resistance in nematodes of beef cattle in south-west Western Australia

Anthelminthic resistance in nematodes of beef cattle is an emerging issue globally with implications for effective parasite control. The prevalence of resistance in beef cattle in the Mediterranean-style climatic zone of south-west Western Australia was assessed on 19 farms, using faecal egg count reduction tests. Pre-treatment faecal worm egg counts were compared with counts at 14 days after treatments with ivermectin (injectable), fenbendazole (oral), or levamisole (oral). A separately grazed group treated with topical ivermectin (pour-on) and sampled at 28 days was included as a comparison against injectable ivermectin. The results demonstrate that resistance is common, with failure of at least one anthelmintic (<95% reduction for each species, by arithmetic means) for either of the major species Cooperia oncophora or Ostertagia ostertagi on 17 of the 19 properties. Resistance to ivermectin (injectable) was demonstrated in C. oncophora in 59% of tests, but ivermectin was fully effective against O. ostertagi by this route. Conversely, O. ostertagi resistant to fenbendazole and levamisole were present on 50% and 67% of farms respectively, with both fully effective against C. oncophora. The finding of Haemonchus placei on several properties was unexpected but the egg counts were low and there is no suggestion of pathogenic effects. An indication of reduced efficacy of the pour-on ivermectin formulation compared to the injectable was apparent against both C. oncophora and O. ostertagi, and this may have implications for resistance development, given the widespread use of topical treatments reported in this region. This survey confirms that anthelminthic resistance in nematodes of beef cattle is common in Western Australia and the pattern of occurrence is in general agreement with surveys elsewhere in Australia and in other countries.