Connectivity in Heterogeneous Landscapes: Analyzing the Effect of Topography

Animal response to landscape heterogeneity directs dispersal and affects connectivity between populations. Topographical heterogeneity is a major source of landscape heterogeneity, which is rarely studied in the contexts of movement, dispersal, or connectivity. The current study aims at characterizing and quantifying the impacts of topography on landscape connectivity. We focus on ‘hilltopping’ behavior in butterflies, a dispersal-like behavior where males and virgin females ascend to mountain summits and mate there. Our approach integrates three elements: an individual-based model for simulating animal movements across topographically heterogeneous landscapes; a formula for the accessibility of patches in homogenous landscapes; and a graphical analysis of the plots of the simulation-based vs. the formula-based accessibility values. We characterize the functional relationship between accessibility values and landscape structure (referred to as ‘accessibility patterns’) and analyze the influence of two factors: the intensity of the individuals’ response to topography, and the level of topographical noise. We show that, despite the diversity of topographical landscapes, animal response to topography results in the formation of two, quantifiable accessibility patterns. We term them ‘effectively homogeneous’ and ‘effectively channeled’. The latter, in which individuals move toward a single summit, prevails over a wide range of behavioral and spatial parameters. Therefore, ‘channeled’ accessibilities may occur in a variety of landscapes and contexts. Our work provides novel tools for understanding and predicting accessibility patterns in heterogeneous landscapes. These tools are essential for linking movement behavior, movement patterns and connectivity. We also present new insights into the practical value of ecologically scaled landscape indices.     

ULTRASONOGRAPHIC EXAMINATION OF THE PHARYNX AND LARYNX OF THE NORMAL DOG

Real-time ultrasonographic examination of the canine larynx was performed in 12 normal dogs using a 7.5-mHz mechanical sector scanner combined with a stand-off. A variety of breeds and ages were examined. All examinations were performed in nonsedated, conscious animals. Transverse scans were found to provide the most reliable and interpretable images. Identification of laryngeal structures included the epiglottis, laryngeal and cricoid cartilages, and the vocal cords. In conscious animals, abduction and adduction of the vocal cords associated with respiration could be identified if the animal was made to pant during the examination. Movement of the vocal cords could also be quantified by pulse-wave Doppler recording. In all animals, recordings were made during inspiration only, with muscular vibration at a rate less than 0.1 m/s.     

Phytosanitary Measures Against Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), in International Trade

The establishment of P. truncatus in Africa has highlighted the inherent weakness of phytosanitary measures against exotic pests. Consideration is given to the need for phytosanitary measures and how patterns of international trade affect phytosanitary control. To prevent the spread of pests such as P. truncatus, large grain shipments can be subject to stringent pest control procedures. However, a significant proportion of grain movement in Africa, both within countries and across borders, occurs informally by both illicit, commercial movement of multiple truckloads of grain and legally by individuals carrying headloads via bush paths or small parcels on public transport. Attempts to locate and inspect the small lots would be impractical. Some recommendations are given on how the spread of P. truncatus in large-scale international trade can be slowed but otherwise it is accepted that in the long-term the prevention of further spread of P. truncatus in Africa is wholly unrealistic.     

LDL对牛精子冷冻-解冻后运动特性的影响

在牛冷冻精液稀释液中,卵黄中的低密度脂蛋白(LDL)对精子起主要保护作用。本研究利用含有7%、8%、9%和10%(w/v)LDL配制成的稀释液制作牛细管冷冻精液(0.25mL/支),冷冻-解冻后,通过计算机辅助分析系统(CASA)对精子运动参数进行分析。结果表明:稀释液中含8%(w/v)LDL时冷冻效果最好,其冻后精子活力平均可达55.6%,显著高于其他组(P<0.01);精子直线速度平均为32.5μm/s,平均路径速度为35.7μm/s,与对照组相比差异显著(P<0.05);a,b级精子可占精子总数的54%。本研究为牛冷冻精液新型稀释液的开发与利用提供了一定的依据。     

Qualitative and quantitative characteristics of the electroencephalogram in normal horses during spontaneous drowsiness and sleep

BACKGROUND: The influence of sleep on the equine electroencephalogram (EEG) has not been well documented. HYPOTHESIS: The objectives were to develop a noninvasive method of electrode placement for recording the EEG in horses and to establish normal EEG parameters for the various states of vigilance. Findings are compared with previously published reports on equine sleep based on electrocorticography (ECoG). ANIMALS: Five neurologically normal horses. METHODS: Overnight EEGs were recorded digitally in association with simultaneous videotaping of the horses' behavior. Data were analyzed by visual inspection, states of vigilance were identified, and representative segments were quantitatively processed. Transient EEG events were examined. RESULTS: Slow wave sleep (SWS) was significantly different (P < .05) in frequency and power from drowsiness and rapid eye movement (REM) sleep. Second-degree heart block was associated with SWS as were transient events commonly recognized in EEGs of humans. Drowsiness and REM sleep were similar. In both, background activity was low-amplitude beta activity admixed with prominent activity of approximately 4 Hz. Standing REM sleep was associated with numerous partial collapses in 1 horse. CONCLUSIONS AND CLINICAL IMPORTANCE: Normative data for several states were described and probable benign variants identified. This information will serve as control data for sedative and anesthetic studies in this species. The sleep patterns observed during this study are those of horses removed from their usual surroundings, and thus may represent those encountered in a clinical environment.     

地下水浅埋条件下包气带水和溶质运移数值模拟研究述评

地下水浅埋条件下包气带水和溶质运移规律是解决土壤盐渍化、地下水污染等环境与生态问题的基本理论基础,基于多孔介质水和溶质运移基本方程的数值模型是研究包气带物质运移的重要手段。通过深入分析土壤水和地下水之间的相互关系,强调在地下水埋深小于其极限埋深的情况下应把地下水作用耦合到包气带水和溶质运移模型中。该文概括总结了现有研究把地下水作用与土壤水模型相耦合的方法,并分析了各种方法的优缺点。在回顾现有土壤水分运动参数和溶质运移参数确定方法的基础上,归纳了包气带水和溶质运移模型从“点”尺度向“田块”尺度扩展的途径,随机方法仍将是今后的研究热点,并有望应用于实践。     

大麦黄矮病毒PAV青海分离物运动蛋白抗血清制备及其与同属BYDVs的血清学关系

 大麦黄矮病毒(Barley yellow dwarf viruses, BYDVs)属于黄症病毒科,主要以蚜虫为介体进行传播,引发多种作物减产或绝收。本文将BYDV-PAV青海分离物的运动蛋白(MP)克隆到原核表达载体pDB-MBP-His上,转化大肠杆菌Rosetta(DE3),在IPTG诱导下表达蛋白分子量约为61 kDa的融合蛋白。将纯化后的蛋白作为抗原免疫‘新西兰’大白兔制备抗血清,Western blot检测本生烟瞬时表达带标签的MP蛋白,结果显示该抗血清效价为1∶32 000,灵敏度达1∶256,且该抗血清可与相差34个氨基酸的PAV015株系以及隶属于黄症病毒属其他的BYDVs(PAS、MAV、KerⅡ和KerⅢ)MP均能发生强烈的血清学反应,具有血清学相关性。本研究制备的大麦黄矮病毒PAV青海分离物运动蛋白多克隆抗体为探索BYDV-PAV运动蛋白的功能以及作用机制打下了基础。     

Spatial and temporal dynamics of land degradation and fluvial erosion in the middle and upper Yangtze River Basin,China

Land degradation in the middle and upper Yangtze has caused loss of cultivable land, sediment deposition in reservoirs and changes in the runoff: sediment yield relationships of major tributaries. The Jialin River and the Dukou-Pingshan sector of the Jingsha River together contribute over 75 per cent of all the sediment carried by the Yangtze at Yichang. As the Jialin catchment has the highest rates of erosion per unit area, high sediment discharges from that river exert a major influence on peak summer sediment discharges on the Yangtze. Even though land degradation is increasing in severity, there is no clear overall pattern or trend in variations in sediment yield since 1950. Some tributaries are affected by major reservoir construction and soil conservation works, others are not.