盐碱胁迫对"丰花2号"花瓣多酚类物质的影响

以"丰花2号"玫瑰为试材,设置不同浓度(0.2％、0.4％和0.6％)的NaCl、Na2CO3、NaCl和Na2CO3(1∶1)9个胁迫处理,以清水为对照,研究了不同处理下"丰花2号"花瓣多酚、黄酮及花青素的含量,及在不同胁迫处理下的时间响应规律,以期为北方盐碱地区玫瑰产业的科学田间管理,提高花瓣保健性物质水平提供参考依据.结果 表明:随着处理的进行,"丰花2号"花瓣多酚、黄酮及花青素含量变化呈先增加后降低的趋势,NaCl、Na2CO3胁迫与"丰花2号"花瓣多酚、黄酮及花青素含量存在相关性.多酚分别在0.6％NaCl胁迫第2周增加最多,增加了12.1％;0.4％Na2CO3胁迫在第1周增加最多,增加了8.2％;0.4％NaCl和Na2CO3混合胁迫第1周增加最多,增加了9.1％;在胁迫第4周以后会明显抑制多酚的合成.黄酮分别在0.4％ NaCl胁迫第1周增加最多,增加了23.1％;0.6％Na2CO3在第3周增加最多,增加了19.9％;0.2％NaCl和Na2CO3混合胁迫第1周增加最多;胁迫第4周以后会明显抑制黄酮的合成.花青素分别在0.6％ NaCl胁迫第3周上升最多,上升了16.1％;0.2％Na2CO3胁迫在第2周增加最多,增加了9.6％;0.6％NaCl和Na2CO3在胁迫第2周上升最多,上升了17.8％;在胁迫第5周以后会明显抑制花青素的合成.     

Visualization of the Anticaging Effect of Ronozyme WX Xylanase on Wheat Substrates

A fluorescence microscope was used for visualization of the anticaging effect of a commercial xylanase on milled wheat, microtome cuts of wheat grains, and digesta samples obtained from piglets 1 or 4 h after feeding a wheat‐based diet (wheat 490 g/kg of diet, barley 100 g/kg of diet, and oats 100 g/kg of diet). Both starchy endosperm and aleurone cell walls were shown to be broken down by Ronozyme WX commercial xylanase. Data obtained by fluorescence microscopy was supplemented with measurements of starch and xylose released as a result of degradation of nonstarch polysaccharides by the xylanase. The results visualize and provide evidence that Ronozyme WX commercial xylanase can overcome the so‐called cage effect. This release of nutrients from their encapsulation in cereal cell wall structures has positive impact on nutrient digestibility and partially explains the positive effect of xylanase supplementation on livestock performance.     

中国罗非鱼产业的国际地位及对外贸易评价

分析我国罗非鱼产业在国际上的比较优势和竞争优势,通过分析近年贸易数据特点及走势,总结我国罗非鱼外贸特征。在此基础上,提出如何稳定增加罗非鱼产品出口,规避贸易风险的建议。     

The temporal trend of urban green coverage in major Chinese cities between 1990 and 2010

Information on changes in urban green spaces and the causes of these changes is important for urban planning. In this study the trends of urban green coverage (UGC) between 1990 and 2010 in 30 major Chinese cities were studied using classified Landsat satellite images. Associations between the trends and natural and socio-economic variables were analyzed using the maximum information-based nonparametric exploration method. The results showed that, overall, the studied cities have become greener over the past two decades. Greening in old city districts and expanded built-up areas (BUAs) led to the increase of urban green coverage at a mean annual rate of 1.51%. However rapid urbanization also caused a dramatic turn-over in vegetation covers. On a regional scale, around 46.89% of original vegetation cover was converted to other land cover types. The trends of UGC cannot be attributed to any one of natural or socio-economic variables alone. The combined influences of economic growth, climate change, and urban greening policies are the most likely causes behind the detected trend. One lesson from this study is that the preservation of existing vegetation cover must be a priority in urban greening programs.     

Classical swine fever (CSF) marker vaccine. Trial I. Challenge studies in weaner pigs

Two commercial marker vaccines against classical swine fever virus (CSFV) and companion diagnostic tests were examined in 160 conventional pigs. To test the vaccines in a "worst case scenario", group of 10 weaners were vaccinated using a single dose of an E2 (gp55) based vaccine at days -21, -14, -10 or -7, and subsequently challenged at day 0. The challenge virus was CSFV 277, originating from a recent outbreak of classical swine fever (CSF) in Germany. In all groups, only 5 out of 10 pigs were challenged; the remaining 5 pigs served as vaccinated contact controls. Also, three control groups, each consisting of 10 non-vaccinated pigs, were challenged in parallel to the vaccinated animals. CSFV could be isolated from all non-vaccinated pigs. Among these pigs 40% displayed a chronic course of the infection (virus positive for more than 10 days). Pigs vaccinated 21 or 14 days before challenge displayed no clinical signs of CSFV after challenge. However, they were still able to replicate CSFV when challenged, as measured by reisolation of CSFV from leukocytes of the directly challenged pigs. CSFV could be isolated from the leucocytes of 25% of the pigs vaccinated 21 days before challenge and 50% of the pigs vaccinated 14 days before challenge. Chronic infection was not observed, but transmission to one vaccinated contact pig occurred. From all pigs vaccinated 10 or 7 days before challenge, CSFV could be reisolated. We observed a chronic course of infection in 5% of pigs vaccinated 10 days before challenge and in 30% of pigs vaccinated 7 days before challenge. The mortality rate was 20% in the pigs vaccinated 10 days before challenge, and varied between 20 and 80% in pigs vaccinated 7 days prior to challenge. The contact animals had lower mortality (0-20%) than directly challenged pigs, probably mirroring the delayed time point of infection. There was thus some protection against clinical illness by both marker vaccines, but not a solid protection against infection and virus shedding. The efficacy of the vaccine was best if used 3 weeks before challenge and a clear correlation between time interval from vaccination to challenge and the level of virus shedding was observed. Each vaccine had its own accompanying discriminatory ELISA, but 18% of the virus positive pigs never seroconverted in these tests.     

Comparison of selective and systematic treatments to control nematode infection of the digestive tract in dairy goats

Resistance to anthelmintics in nematode parasite of the digestive tract is a major concern in small ruminants and particularly in goats. One possible solution to limit the development and spread of resistance is to give treatments on a selective basis, i.e. by targeting the most susceptible animals within a flock rather than treating all the animals. In dairy goats, epidemiological studies have shown that, within a flock, goats in first lactation and the multiparous ones with the highest level of milk production were highly receptive to parasite infection. The objective of the study was to assess whether selective treatments could achieve a level of control of nematodes similar to systematic drenching. A similar experimental design was applied for two successive years. An experimental flock of 120 dairy goats was divided into two groups. All the goats from group SYS (systematic treatment) were drenched at mid-grazing season (July). In contrast, anthelmintics in group SEL (selective treatment) were restricted to the goats in first lactation plus the high producers. Overall, these treated goats represented 48% of the flock in year 1 and 66% in year 2. After treatments, both groups grazed on separate pastures. Parasitological and pathophysiological measurements were performed monthly. The results indicate a similar level of egg excretion in the two groups. The pathophysiological parameters (pepsinogen and phosphate concentrations) were also similar in the two groups, as well as the milk production for the 2 years. These results suggest that a targeted use of anthelmintics may allow efficient control of gastrointestinal nematodes whilst resulting in a predicted reduction in the selection pressure for the development of anthelmintic resistance.     

Experimental study of the mechanical behaviour of thin slices of maturating green poplar wood using cyclic tensile tests

In this study, longitudinal cyclic tensile tests were performed on green wood samples of Populus cv I4551. Complex mechanical behaviour, such as permanent set in terms of displacement and strain-dependent stiffness, was found. A linear relationship between stiffness and strain enabled each sample to be characterized. A large-scale experimental campaign led to the observation of the evolution of temporal and spatial intra-ring mechanical behaviour of intra-ring sliced specimens during wood maturation and tree gravitropic response. The results showed that tension wood lamellas exhibit strain hardening behaviour whereas normal wood lamellas exhibit strain softening behaviour. Temporal variations in the strain hardening behaviour of tension wood lamellas occurred once cell wall deposition was achieved. Moreover, no correlation was found between infradensity and mechanical behaviour of lamellas. These results show that cells undergo temporal variations in their properties due to a complex maturation process.     

Drought effects on water use efficiency, freezing tolerance and survival of Eucalyptus globulus and Eucalyptus globulus × nitens cuttings

Genetic improvement of Eucalyptus genotypes for drought and frost resistance is essential for successful intensive management of commercial plantations. Understanding the physiological mechanisms that relate water use and frost resistance for highly deployed genotypes may allow for better prediction of their future performance, genetic selection and seedling management for site specific purposes. We studied whether instantaneous water use efficiency (WUE _i ) may serve as drought, freezing and photoinhibition tolerance predictor by studying its response on six E. globulus clones (Eg1–Eg6) and four E. globulus × E. nitens hybrid seedlings (Egn1–Egn4) under drought and irrigated (control) treatments. Net photosynthesis (A) and transpiration (E) were studied using a gas exchange system in order to calculate WUE _i (A/E). Simultaneous chlorophyll a fluorescence measurements were performed to assess the non photochemical quenching components. Frost tolerance of plants under control and drought treatments were evaluated by measuring temperatures that exert 50% photoinactivation of photosystem II. Finally, drought tolerance was evaluated by plant survival within each genotype after rehydration. Our results showed significant genotype variability in the rate of soil and xylem water potential decrease during drought. While most of the genotypes reached ?4.0 MPa in about 35 days of drought, genotypes Eg6 and Egn4 required 56 days of drought to reach this xylem water potential. WUE _i exhibited significant differences among genotypes and irrigation treatments. Genotypes Eg5 and Egn4 increased their WUE _i between 70 and 80% after drought. This was associated with a more conservative control of water loss at the stomatal level combined with maintenance of relatively higher rates of net photosynthesis than the other genotypes under drought conditions. Plants exposed to drought were more freezing tolerant than control plants, having in average 3°C lower LT₅₀ than well irrigated ones. There was no a clear correlation between WUE _i and drought tolerance or drought-induced photoinhibition, however WUE _i was inversely correlated with LT₅₀. Our results suggest that WUE _i is not suitable by itself to select drought tolerant genotypes, but may provide evidence for discarding drought sensitive genotypes. In addition, it could provide valuable information to select for freezing tolerance.     

Thermal Stability of Selected Natural Red Extracts Used as Food Colorants

The color degradation of aqueous solutions of six natural red pigment extracts (elderberry, red cabbage, hibiscus, red beet, Opuntia fruits and red cochineal) used commercially as food colorants was investigated at temperatures between 50 and 90 °C. Color degradation was studied in respect to both spectral properties and visual color. The remaining absorbance at 535 nm as a function of the incubation time and temperature was used to quantify the degradation process. Red cochineal was the most thermoresistant extract with a remaining absorbance of 95 % after 6 h at 90 °C. Anthocyanin extracts (elderberry, red cabbage, hibiscus) showed remaining absorbance percentages of 63.8, 46.1 and 26.7, respectively. Betacyanin extracts (red beet, Opuntia fruits) were the most thermosensitive maintaining only 12.5 and 1.7 %, respectively, of the initial absorbance at 535 nm. Applying a first-order kinetic model to the degradation processes, reaction rate constants (k) and half-life periods (t _1/2 ) were calculated. The temperature dependence of the degradation rate constant obeyed the Arrhenius relationship, with activation energies (E _a ) ranging between 3.02 and 53.37 kJ?mol^?1. The higher activation energy values indicated greater temperature sensitivity. Changes in visual color attributes corroborated the high thermal stability of the red cochineal extract.     

酵母双杂交表达载体pGBKT7_NPR1与pGADT7_NPR1的构建及酵母菌的转化

NPR1是水杨酸介导的系统获得性抗性（SAR）途径中不可或缺的一个转录辅助因子。在SA诱导下,NPR1被转运至细胞核内并与一些转录因子结合,以启动下游基因的表达。本研究通过PCR扩增获得拟南芥中NPR1基因CDS序列,经过限制性内切酶酶切后在T4连接酶作用下分别克隆至pGBKT7与pGADT7酵母表达载体上,并成功将其转化至Gold酵母菌株中。为利用酵母双杂交筛选NPR1参与形成的转录复合体中其它可能存在的蛋白质并阐明其在植物防御信号传导途径中的互作模式奠定了基础。