中油821接种菌核病菌丝体后的生化反应

以油菜第3片真叶人工接种菌核病菌丝体，研究中油821抗（耐）菌核病与植株叶片硫甙含量、POX活性的关系。结果显示，第3叶片接种区域的各种硫甙含量增加，以吲哚族硫甙表现突出，接种后7d吲哚族硫甙含量达1158nmol/ml，比不接种对照增加70倍，第3叶片非接种区域的吲哚族硫甙含量比不接种对照增加7－30倍，第5、6叶片及第3叶叶柄也表现接种后嘴哚族硫甙增加。所有接种材料均在第3d产生了芳香族硫甙，接种叶POX活性表现持续上升。     

Myeloperoxidase,a leukocyte-derived vascular NO oxidase

Myeloperoxidase (MPO) is an abundant mammalian phagocyte hemoprotein thought to primarily mediate host defense reactions. Although its microbicidal functions are well established in vitro, humans deficient in MPO are not at unusual risk of infection. MPO was observed herein to modulate the vascular signaling and vasodilatory functions of nitric oxide (NO) during acute inflammation. After leukocyte degranulation, MPO localized in and around vascular endothelial cells in a rodent model of acute endotoxemia and impaired endothelium-dependent relaxant responses, to which MPO-deficient mice were resistant. Altered vascular responsiveness was due to catalytic consumption of NO by substrate radicals generated by MPO. Thus MPO can directly modulate vascular inflammatory responses by regulating NO bioavailability.     

The combined effects of thinning and prescribed fire on carbon and nutrient budgets in a Jeffrey pine forest

? Both burning and harvesting cause carbon and nutrient removals from forest ecosystems, but few studies have addressed the combination of these effects. For a Pinus jeffreyii forest in the Sierra Nevada Mountains of California, we posed the question: what are the relative impacts of thinning and subsequent burning on carbon and nutrient removals?

? The thinning methods included whole-tree thinning (WT, where all aboveground biomass was removed) cut to length (CTL, where branches and foliage were left on site in a slash mat on top of skid trails) and no harvest (CONT). Total C and nutrient exports with thinning and burning were greater in the WT and CTL than in the CONT treatments. Total C and N removals were approximately equal for the WT and CTL treatments, although harvesting dominated exports in the WT treatment and burning dominated exports in the CTL treatment. Total removals of P, K, Ca, Mg and S were greatest in the WT treatments, where harvesting dominated removals.

? Comparisons of nutrient removals with ecosystem capital and calculations of potential replenishment by atmospheric deposition suggested that N is the nutrient likely to be most depleted by harvesting and burning treatments.

     

利用介质阻挡放电等离子体杀灭鲜榨果汁大肠杆菌

与传统热杀菌相比,非热杀菌能较大程度地保持食品中营养成分,节约能耗。为了进一步研究非热杀菌技术,利用自行设计的介质阻挡放电反应器（DBDR）,以鲜榨果汁为杀菌介质,研究了DBDR所产生的低温等离子体（LTP）的杀菌效果和对鲜榨果汁品质的影响。采用响应面法建立了介质阻挡放电等离子体（DBDP）杀灭鲜榨果汁饮料中大肠杆菌的二次多项数学模型,验证了模型的有效性,并探讨了循环次数、pH值、温度及电压对DBDP杀灭大肠杆菌的影响,优化出杀灭7个数量级大肠杆菌（E.coli）ATCC 8739的工艺参数为：循环次数6次,pH值 3.14,温度39.72℃,电压21.42 kV。为进一步研究DBDP的杀菌规律和探讨杀菌机理奠定了数学基础,同时,此模型的决定系数R2达到0.9817,可推广应用到其他果蔬汁的杀菌处理,提高鲜榨果蔬汁的品质和质量安全。     

Growth and feed performance,digestibility and acute stress response of juvenile grouper (Epinephelus fuscoguttatus) fed diets with hydrolysate from milkfish offal

Nutritional qualities of fish processing by‐products can further be improved through enzymatic hydrolysis. The objective of this study was to elucidate the efficacy of hydrolysed milkfish offal at different inclusion levels when fed to juvenile grouper, Epinephelus fuscoguttatus, with an initial body weight of 2.88 ± 0.06 g. The animals were fed for 56 days with seven diets supplemented with 0 (control), 5%, 15% and 25% of milkfish offal (MO) and milkfish offal hydrolysate (MOH). The diets were formulated to be isonitrogenous (45%) and isolipidic (11%). The diets were assigned to 21 tanks (15 fish per tank) with each diet having three replicates. Results from the experimental trials indicated that feed conversion efficiency, feed intake and weight gain of fish significantly (P < 0.05) improved when fed diets with MOH. No significant differences within the rest of the dietary treatments were observed. Survival rate (>90%) did not differ in all the dietary treatments. Proximate composition (crude protein, crude fat and ash) indicated no significant difference among fish fed from all the dietary treatments. Apparent digestibility of MOH indicated a 95% and 66% digestibility for protein and dry matter respectively. Plasma stress parameters (cortisol and glucose) were not influenced by the dietary treatment when fish were subjected to an acute stressor (5‐min chasing). Liver morphology indicated normal hepatocyte shape and the presence of lipid droplets in fish fed from all the dietary treatments. The results indicated that milkfish offal processed as hydrolysate can be utilized in grouper diets and can promote growth and feed efficiency when supplied at 10–15%.     

Root growth,and microorganisms associated with the rhizoplane and root zone soil of a native C4 grass on burned and unburned sand prairies

We investigated the root growth of native Schizachyrium scoparium, little bluestem grass, and the seasonal abundance of rhizoplane and root zone soil microorganisms on burned and unburned sand prairies. Root growth and abundances of rhizoplane and root zone microorganisms were greater in burned than unburned sites. Microbe populations were nearly always higher on the rhizoplane than in the root zone soils, although they were not always significantly different. The seasonal dynamics of total bacteria, total fungi, fluorescent pseudomonads, and microorganisms that decompose chitin, cellulose, and protein varied between burned and unburned sites. Some microbial populations showed significant, though weak, relationships with root growth. Populations of most microorganisms were usually highest from June through August, when roots were being shed following the peak standing crop of root mass in May. The production of fine roots on burned sites early in the growing season and the consequent shedding of fine roots probably have an important effect on microbe population dynamics.     

Labile inorganic manganese — An overlooked reason for fish mortality in acidified streams?

Acid deposition has caused acid episodes and elevated concentrations of metals like Fe, Al and Mn in streams in mountain regions of Sweden. In streams in the area of Lofsdalen, central Sweden, an episode in 1978 during snow melt caused massive downstream migrations of fish. Acid episodes have occurred yearly since then. pH of 4–4.5 and high concentrations of total Fe, Mn and Al were measured during these spates. Liming measures have been carried out in a number of catchments in order to increase the pH and try to decrease the leaching of metals. The lime has been delivered on wetlands, seepage areas and areas covered by meltwater during the spring. Cage experiments were carried out with yearling brown trout in the springs of 1982, and 1985–86. Fe, Al and Mn were analysed in water samples and on/in the gills of dead and live brown trout. There were no significant correlations between mortality or average survival time and total concentrations of Fe, Al or Mn in the water or on/in the gills. Average survival time was positively correlated to pH (p< 0.01). Metal speciation was carried out in 15 experiments in 1985 and ?86. A canonical discriminant analysis showed that pH and the concentration of labile inorganic manganese in the water explained all the observed mortality (can. corr 0.89, p< 0.001). The rate of accumulation of manganese on/in the gills was correlated to the concentration of labile inorganic manganese in the water (p<0.01, r²=0.54, linear regression).     

Intense fragmentation and deep burial reduce emergence of Rumex crispus L.

Abstract

Mechanical control through different tillage methods is a common measure against perennial weeds. However, non-optimal tillage can potentially increase the vegetative regeneration instead of reducing it. Aspects of regenerative capacity in the perennial weed species Rumex crispus L. was studied in three pot and box experiments as follows: (1) regeneration from different root fragments under varying test conditions; (2) effects of root size and burial depth on time of emergence and emergence rate; and (3) effects of burial depth and cutting on biomass production and seed production. In experiment 1, sprouting occurred mainly from the neck of the roots, consisting of underground stem tissue. A few shoots were observed also from the upper half of the true taproot and from a side root. No difference in sprouting was found between test conditions. In experiment 2, total emergence rate was positively related to root size and negatively related to burial depth. Time to first emergence was defined by an interaction between the two factors. Roots larger than 100 g gave rise to a high degree of emergence from all burial depths, while emergence from roots weighing 20–30 g was less than 30% from 12 cm and nonexistent from 18 cm. When emergence and shoot production were tested under different cutting regimes (experiment 3), the separated top fragments of the roots sprouted faster and produced more shoot biomass than intact rootstocks, even at a second harvest. Our results indicate that fragmentation can stimulate sprouting from the regenerative tissue of the taproot. Hence, if tillage is carried out as weed control it is important that root fragments are buried at ploughing depth, especially if the population consists of adult plants.     

Potential impacts of water harvesting and ecological sanitation on crop yield, evaporation and river flow regimes in the Thukela River basin, South Africa

In this study we explore the potential impacts of two strategies, namely in situ water harvesting (in situ WH) and fertilisation with stored human urine (Ecosan), to increase the water and nutrient availability in rain-fed smallholder agriculture in South Africa's Thukela River basin (29,000 km²). We use the soil and water assessment tool (SWAT) to simulate potential impacts on smallholder maize yields, river flow regimes, plant transpiration, and soil and canopy evaporation during 1997-2006. Based on the results, the impacts on maize yields are likely to be small with in situ WH (median change: 0%) but significant with Ecosan (median increase: 30%). The primary causes for these effects are high nitrogen stress on crop growth, and low or untimed soil moisture enhancement with in situ WH. However, the impacts vary significantly in time and space, occasionally resulting in yield increases of up to 40% with in situ WH. Soil fertility improvements primarily increase yield magnitudes, whereas soil moisture enhancements reduce spatial yield variability. Ecosan significantly improves the productivity of the evaporative fluxes by increasing transpiration (median: 2.8%, 4.7 mm season⁻¹) and reducing soil and canopy evaporation (median: −1.7%, −4.5 mm season⁻¹). In situ WH does not generally affect the river flow regimes. Occasionally, significant regime changes occur due to enhanced lateral and shallow aquifer return flows. This leads to higher risks of flooding in some areas, but also to enhanced low flows, which help sustain aquatic ecosystems in the basin.