Cortisol release,heart rate,and heart rate variability in transport-naive horses during repeated road transport

Domestic animals are often repeatedly exposed to the same anthropogenic stressors. Based on cortisol secretion and heart rate, it has been demonstrated that transport is stressful for horses, but so far, changes in this stress response with repeated road transport have not been reported. We determined salivary cortisol concentrations, fecal cortisol metabolites, cardiac beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-naive horses (N = 8) transported 4 times over a standardized course of 200 km. Immunoreactive salivary cortisol concentrations always increased in response to transport (P < 0.001), but cortisol release decreased stepwise with each transport (P < 0.05). Concentrations of fecal cortisol metabolites increased from 55.1 ± 4.6 ng/g before the first transport to 161 ± 17 ng/g the morning after (P < 0.001). Subsequent transport did not cause further increases in fecal cortisol metabolites. In response to the first transport, mean RR interval decreased with loading of the horses and further with the onset of transport (1551 ± 23, 1304 ± 166, and 1101 ± 123 msec 1 d before, immediately preceeding, and after 60–90 min of transport, respectively; P < 0.05). Decreases in RR interval during subsequent transports became less pronounced (P < 0.001). Transport was associated with a short rise in the HRV variable standard deviation 2 (P < 0.001 except transport 1), indicating sympathetic activation. No consistent changes were found for other HRV variables. In conclusion, a transport-induced stress response in horses decreased with repeated transport, indicating that animals habituated to the situation, but an increased cortisol secretion remained detectable.     

二维虚拟土壤中溶质迁移行为的数值模拟研究

利用Voronoi图逐级碎裂方法,在二维正方网格上构造出不同等级的虚拟土壤来仿真具有丰富孔隙结构的真实土壤,并借助于随机行走模型,数值模拟了溶质粒子在该虚拟土壤中的迁移行为。结果表明,溶质粒子表现出反常扩散行为。对有偏倚的随机行走模型,其均方位移与时间呈正比关系∝tK,即扩散系数D=K-1,长时间的K值更大,溶质粒子扩散更快;首次穿越时间满足正态对数分布,说明溶质粒子迁移是一阶随机过程;由连续时间随机行走理论,发现溶质粒子扩散非费克现象明显。同时发现不同的土壤孔隙结构及随机行走类型所对应的拟合参数不同,即它们也影响溶质粒子的迁移行为。该研究有利于人们从理论上定性理解和预测水及溶质在有大孔隙土壤中的迁移,保护地下水环境。     

利用土壤颗粒的沉降粒级研究泥沙的迁移与分布规律

了解不同粒径泥沙迁移运动规律,有助于深入理解侵蚀条件下碳、氮、磷等元素的生物地球化学过程。土壤营养元素的迁移转化与泥沙颗粒的运动规律密切相关,而泥沙的运动规律由颗粒大小、性状、孔隙度和密度等因素共同决定。依据泥沙颗粒沉降速度分选的原理,针对中国两种典型侵蚀土壤(红壤和黄绵土),分别进行了土壤机械组成(矿质土粒分选)和沉降速度分选测定。结果表明,土壤颗粒的沉降粒级可有效区分红壤和黄绵土中不同粒径团聚体的沉降速度,能够更加准确地反映出同一粒径颗粒因性状、密度和孔隙度的差异而形成的不同沉降速度。相对于质地疏松的黄绵土,红壤的机械组成显示,有86.9%的有机碳与≤32μm的矿物颗粒相结合,很有可能随悬移过程汇入下游水体。但土壤颗粒沉降速度分布表明,约有90.5%的红壤有机碳与等效石英粒径≥63μm的团聚体相结合,易在经历较短的迁移过程后,快速沉积于下坡面。这表明,现有的土壤侵蚀模型大多利用土壤机械组成(即矿质粒径大小)在反映泥沙运动或元素迁移规律方面存在片面性。土壤的团聚过程可有效缩减有机碳和无机碳的迁移距离,从而使其更易沉积于陆生环境。土壤颗粒的沉降速度分级对认识泥沙颗粒和养分元素在侵蚀—迁移—沉积过程中的生物地球化学过程提供了新的途径和视角。     

Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in the field

Allelopathy is a biological phenomenon where plants have harmful effects on growth of surrounding plants through the production of chemical substances. Here we focus on allelochemical processes which operate belowground, can influence plant interactions and therefore potentially affect plant community structure. Soil hyphae of arbuscular mycorrhizal fungi (AMF) may enhance transport processes in the soil matrix by providing direct connections between plants facilitating infochemical exchange.In a two-component field study we showed that soil hyphae likely play a crucial role in movement of allelochemicals in natural soils and greatly expand bioactive zones by providing effective transport pathways for chemical compounds. First, we tested the effects of Juglans regia leaf litter extract addition in intact or disrupted hyphal networks and simultaneously determined growth reducing effects on sensitive Lycopersicon lycopersicum plants. Second, we analyzed the effect of juglone on tomato by directly adding leaf litter. In both approaches we found an increase of juglone transport if a hyphal network was present, resulting in reduced growth of target plants.Our results, together with previous work, add to the body of evidence for hyphae of soil fungi playing an important role in the transfer of allelochemicals and effectively acting as transport highways in the field. We suggest that hyphal connections, mostly formed by AMF, increase the effectiveness of allelochemicals in natural systems and can play a crucial role in chemical interaction processes in the soil.     

Experimental determination of sediment transport capacity of rill flow over sandified loess slope

Rill erosion is affected by the sand particle content in soil, especially in the wind and water erosion transition region of the Loess Plateau. The sediment transport capacity (STC) is a key parameter in rill erosion research, assessing the impact of aeolian sand intrusion on the STC of rill flow is of importance for a better understanding of rill erosion. This study aimed to assess the effect of aeolian sand intrusion on the STC on sandified loess slopes, with typical slopes and flow discharges, using a flume system which consisting of a sediment-feeding and a sediment-supply/settlement flume. The sediment feeding flume was jointed by 10° higher than that of the sediment measurement flume section. Three flow discharges (2, 4, and 8 L min⁻¹) and four slope gradients (5°, 10°, 15°, and 25°) were used to represent the natural hydrological conditions under three intrusion rates (SIR) of aeolian sands (10%, 20%, and 50%). The results show that STC increased with slope gradient and flow discharge, and the relationship between the STC and the SIR was significantly affected by the slope gradient; the STCs decreased with the SIR on a slope of 5° but increased with the SIR on steep slopes of 15°–25°, implying a significant impact of slope gradient on the relationship between SIR and STC. The SIR of 50% resulted in the highest sediment concentration nearly 1200 kg m⁻³ on slopes of 25°. On sandified loess slopes of 10%, 20%, and 50% SIR, the STC were about 30%, 46%, and 57% higher than on loess slopes, indicating an increased erosion rate by sand particle intrusion into loess soil. These results highlight the impact of sand intrusion on STC of rill flow and provide deeper insights into the soil loss process on the sandified loess slope.     

地下环境中胶体促使下的污染物运移研究进展

大量的研究证据表明,胶体能促使地下环境中污染物的运移。胶体的沉积、释放和运移等动力学过程受许多因素的控制,如胶体的表面性质(亲水或疏水)、胶体的稳定性、水溶液的化学组分、离子强度、pH值和水的流速等。许多研究者已提出了考虑不同影响因素的模型从理论上或用实验室土柱试验来模拟胶体的运移行为。在未来应加强野外条件下不同类型的天然介质中胶体促使下污染物运移的影响因素、作用机制和运移过程的研究,这有助于人们提出有效的策略或发展新的治理技术以防止污染的扩大或修复污染,最终达到保护地下环境的目的。     

Prevalence of anti-Toxoplasma gondii antibodies in serum and aqueous humor samples from cats with uveitis or systemic diseases in France

The present study sought to elucidate whether Schistosoma japonicum eggs could survive a passage through dogs and chickens. Three dogs and three chickens were used for the experiment. The dogs were allowed to eat goat faeces containing 80 S. japonicum eggs per gram. The chickens were given 2 ml of water containing more than 100 S. japonicum eggs per ml. The hatchability of the eggs was 51.8% prior to administration. All faeces were collected for 3 days from the dogs and for 2 days from the chickens and egg excretion and hatchability were measured. The results showed that nearly 50% of the eggs administered to the dogs were recovered in the faeces during the first 2 days and during the first 25 h 39% of the recovered eggs were viable and able to hatch. In the chickens 9% of the administered eggs were recovered within 27 h and within the first 3.5 h after administration 19% of the recovered eggs were viable and able to hatch. The results suggest that both dogs and chickens may act as transport hosts for S. japonicum in endemic areas.     

The influence of different doses of α-tocopherol and ascorbic acid on selected oxidative stress parameters in in vitro culture of leukocytes isolated from transported calves

The objective of the study was to assess in vitro the influence of various doses of two different antioxidants, α-tocopherol and ascorbic acid, on protective mechanisms against ROS in white blood cells obtained from calves exposed to transport, and to compare these results with those obtained from non-transported animals.The concentrations of lipid peroxidation products in leukocytes and in the retained medium were assessed by determining the level of ThioBarbituric Acid Reactive Substances (TBARS). Total antioxidant status in the leukocytes and the medium were estimated using a ferric-reducing ability of plasma (FRAP) assay. Leukocyte viability was determined using the trypan blue reduction test.The study demonstrated that after bovine leukocytes (WBC) were incubated in vitro with α-tocopherol and ascorbic acid, peroxidation intensity decreased and total antioxidant capacity increased. The results of the study reveal that these antioxidants in concentrations over 0.1 mg/ml have a major impact on free radical activity on bovine white blood cells and on cell viability during transport of animals.Based on this study, we suggest that incubation of the leukocytes with antioxidants decreases the oxidative stress development, which can be helpful in protection of the immunological cells during bovine respiratory disease.     

近代河南水运与农业商品化关系略论

河南在传统时期直至近代,一直是农业大省,工业发展极为缓慢,且多为小手工业:1949年,全省工业产值仅2.98亿元,比1936年下降36.8%;而1936年,近代工业产值仅占工农业总产值的5.1%、工业总产值的30.4%,远远落后于全国平均水平(1)。因此,河南近代史上的经济变迁,最重要的即是农业的商品化。一般认