Comparing the behavioural thermoregulation response to heat stress by Atlantic salmon parr (Salmo salar) in two rivers

Climate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon (Salmo salar) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature surpasses this threshold, juvenile salmon exploit thermal heterogeneity to behaviourally thermoregulate, forming aggregations in coolwater refuges. This study aimed to determine whether the behavioural thermoregulation response is universal across rivers, arising from common thermal cues. We detailed the temperature and discharge patterns of two geographically distinct rivers from 2010 to 2012 and compared these with aggregation onset temperature. PIT telemetry and snorkelling were used to confirm the presence of aggregations. Mean daily maximum temperature in 2010 was significantly greater in the OR versus the LSWM (p = 0.005), but not in other years (p = 0.090–0.353). Aggregations occurred on 14 and 9 occasions in the OR and LSWM respectively. Temperature at onset of aggregation was significantly greater in the OR (T_onset = 28.3°C) than in the LSWM (T_onset = 27.3°C; p = 0.049). Logistic regression models varied by river and were able to predict the probability of aggregation based on the preceding number of hours >23°C (R² = 0.61 & 0.65; P₅₀ = 27.4°C & 28.9°C; in the OR and LSWM respectively). These results imply the preceding local thermal regime may influence behaviour and indicate a degree of phenotypic plasticity, illustrating a need for localised management strategies.     

党的先进性建设如何借鉴国际共产主义运动的基本经验教训

前苏联及东欧共产党丧失执政地位使国际共产主义运动遭受重大挫折的原因有很多，最重要的因素是苏东共产党蜕化变质。没有按照党的先进性来建设党，丧失了党的思想、理论、阶级基础、群众基础、前进方向的先进性，从而失去了它作为无产阶级先锋队的作用，削弱乃至丧失了执政能力，最终葬送了社会主义事业也葬送了党的自身。国际共产主义的经验教训对中国共产党人在全党开展先进性建设的启示是深刻而巨大的：在新的形势下必须坚持党在指导思想上与时俱进；必须从严治党，建立党的先进性建设长效机制；必须加强党的执政能力建设。巩固党的执政基础；必须加大反腐败力度。永葆党的先进性。     

Use of space by bank voles (Clethrionomys glareolus) in a polish farm landscape

Movements of bank voles (Clethrionomys glareolus) were studied in a farmland mosaic in Poland. Distances crossed by animals in short-time periods are significantly longer in heterogenous than in homogenous habitats. In long-time and large-spatial scales, a significant portion of the animals in a population travel among habitat elements of the mosaic, reducing the degree of isolation of patch populations and decreasing the probability of local extinction.     

Movement of Xanthomonas campestris pv. vitians in the stems of lettuce and seed contamination

Xanthomonas campestris pv. vitians , the causal agent of bacterial leaf spot of lettuce (BLS), can be seedborne, but the mechanism by which the bacteria contaminates and/or infects lettuce seed is not known. In this study, the capacity of X. campestris pv. vitians to enter and translocate within the vascular system of lettuce plants was examined. The stems of 8- to 11-week-old lettuce plants were stab-inoculated, and movement of X. campestris pv. vitians was monitored at various intervals. At 4, 8, 12 and 16 h post-inoculation (hpi), X. campestris pv. vitians was recovered from 2 to 10 cm above (depending on stem length) and 2 cm below the inoculation site. Xanthomonas campestris pv. vitians was also recovered from surface-disinfested stem sections of spray-inoculated plants. Together, these results are consistent with X. campestris pv. vitians invading and moving systemically within the vascular system of lettuce plants. To investigate the mechanism of seed contamination, lettuce plants at the vegetative stage of growth were spray-inoculated with X. campestris pv. vitians and allowed to develop BLS. Seed collected from these plants had a 2% incidence of X. campestris pv. vitians external colonization, but no bacteria were recovered from within the seed.     

香蕉束顶病毒(BBTV)侵染对寄主内源激素的影响

 本试验用ELISA方法测定了香蕉感染束顶病毒(BBTV)后植株体内的3种内源激素,赤霉素(GA₃)、玉米素类(iPAs)和脱落酸(ABA)的变化。结果表明,感株的GA₃水平在侵染过程中虽有微弱增加,但含量和增长速度显著低于健株对照;iPAs在接种BBTV第14天后明显下降,并维持较低水平;ABA在BBTV侵染后被大量诱导增加并不断积累,在接种后第35天测定含量最高,为对照的3.34倍。试验还同时检测了BBTV在侵染过程中的运转。用间接ELISA测定的接种叶和顶叶的BBTV含量显示:接种21天后BBTV在接种叶和顶叶中还大量增殖,呈系统性分布。但寄主的症状在接种35天后才逐渐在顶叶表现。以上结果表明:香蕉束顶病的症状表现似乎主要与病株中的内源激素的失调有关,而与BBTV在体内的运转并不直接相关     

近32年来新疆地区植被覆盖的时空变化

基于拟合的长时间序列数据监测新疆植被时空动态变化。结果表明,近32年来,新疆植被总体呈现增加趋势,但存在明显的阶段变化和空间差异;植被生长季NDVI值西部和西北部高,东部和东南部低;1982-2013年间新疆植被改善面积大于退化面积,绿洲农田植被覆盖区改善明显、草原区退化严重;整个研究区域的植被重心从北向南移动,天山以北的植被重心呈现西南-东北方向移动,天山以南呈现近似东西方向的移动。     

Movement rules for juvenile steelhead: dynamic linking of movement behaviour to habitat and density

We incorporated explanatory factors including stream habitat type and fish density into individual‐based models with dynamic connections among adjacent habitat units to infer dispersal behaviour of juvenile steelhead Oncorhynchus mykiss in a Great Lakes watershed. We used mark–recapture data and an inverse modelling approach to estimate daily probability of steelhead moving out of a habitat unit, P(move), according to four competing models. The models used included (i) a null model where all fish had equal movement probability; (ii) a habitat‐dependent model where P(move) depended on the habitat type; (iii) a density‐dependent model of P(move); and (iv) a model where P(move) depended on both density and habitat type. The habitat‐dependent model provided the most parsimonious fit to the observed data according to Akaike's information criteria (AICc). In the null model, P(move) averaged 0.70, whereas P(move) averaged 0.75 in pools, 0.68 in riffles and 0.73 in runs in the habitat‐dependent model.     

Evaluation of European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) larval movement and survival in structured and seed blend refuge plantings

Blending Bacillus thuringiensis (Bt) corn and non-Bt corn seeds in the same bag is a convenient and easier compliance solution to satisfy refuge regulations. However, there has been considerable debate and concern about larval movement of the target insects in a seed blend because of its potential effect on the development of resistance. Reported here are studies to determine the larval movement of European corn borers, Ostrinia nubilalis (Hübner), in a seed blend compared to a structured refuge and their effects on survival, feeding injury and larval fitness. Also evaluated is the relative performance of a purple-seeded corn hybrid as a surrogate host plant for tracking gene flow. Seed blend and structured refuge arrangements of Agrisure GT/CB/LL Bt corn expressing Cry1Ab and isoline plants were evaluated at two locations in 2013 and 2014 by manually infesting refuge plants with first and second generation corn borer larvae. The majority of leaf and stalk injury was recorded on the refuge plant, which amounted to 66–83% of the total tunnel length. In both refuge arrangements, plant injury and the number of larvae recovered significantly decreased on neighboring plants with increasing distance away from the refuge plant in the same row. The relative decline in injury was much more pronounced in the seed blend, with neighbor Bt plants experiencing very minor tunneling or no injury at all due to the high dose trait. Eighty-nine percent fewer live larvae were also found on neighbor Bt plants in the seed blend compared to those found in the structured refuge plots. Larvae that moved to Bt plants as well as older instars that were manually placed on Bt plants failed to complete development. Comparison of the number of tunnels and larvae recovered per refuge plant indicated that the seed blend may not produce as many susceptible individuals as those produced in a structured refuge arrangement. Although the purple-seeded hybrid showed lower levels of ear and stalk injury, it could serve as an appropriate surrogate refuge plant to track gene flow.     

整秆式甘蔗收获机内物流排杂高速摄影分析

为了研究整秆式甘蔗收获机内物流排杂运动机理,研制了甘蔗收获机内物流排杂试验台,并利用高速摄像机拍摄了甘蔗与蔗叶在物流通道内的运动全过程,并对图像进行分析。结果表明,甘蔗在物流运动过程中发生弹跳、扭转和弯曲变形,在剥叶运动过程中发生断尾,并且通过排杂装置将蔗叶与甘蔗分离后排出。通过建立甘蔗收获机内各部件元件与甘蔗、蔗叶的简化力学模型,结合甘蔗和蔗叶的力学特性分析了甘蔗和蔗叶在物流通道内的运动机理。甘蔗在物流运动中主要受到的作用力为各部件对甘蔗的轴向力、垂直于甘蔗运动方向的切向力和摩擦力。     

基于HYDRUS-2D的地下滴灌下水分运移数值模拟研究

利用HYDRUS-2D软件模拟了地下滴灌条件下滴头周围黏壤土的土壤水分动态,并与田间观测进行对比;通过分析不同滴头流量对试验地土壤湿润模式的影响,明确了最佳灌水技术参数。结果表明,HYDRUS-2D软件模拟结果与观测值一致,体积含水率均方根误差为1.2%~4.5%,湿润范围均方根误差变化范围为2.1~3.87cm。