转基因及常规水稻幼苗对潮霉素敏感性的研究

研究了转基因及常规水稻幼苗叶面喷施潮霉素B溶液后的反应。结果发现,常规水稻吸收潮霉素B后,叶片会出现以褐斑为特征的中毒症状。在50～100mgL浓度范围内,褐斑的数目和面积随时间和浓度的增加而增加,溶液中滴加DMSO可提高潮霉素对稻苗的毒性。浓度在75mgL及以上时,喷后第7天,处理的所有幼苗都出现症状。而浓度在50mgL时,个别幼苗经处理后未出现中毒症状。在上述浓度范围内,带潮霉素磷酸转移酶基因(hpt)的Bt转基因水稻(克螟稻)幼苗均未出现中毒症状。苗期鉴定与抽穗前后成株期鉴定的结果相一致。讨论了叶面喷施潮霉素B溶液在转基因水稻育种和筛选潮霉素敏感转基因水稻突变体中的可能应用。     

中国黄土高原黄土-古土壤序列的红度对古气候的指示意义

Comparisons of red ratings (RR) with Fe_d, Fe_d/Fe_t, clay content, and magnetic susceptibility (x) of two loess-paleosol sequences at Luochuan and Lingtai on China's Loess Plateau were conducted to study the possible relationship between RR and pedogenic degrees of the two loess-paleosol sequences, and to discuss whether the RR could become new paleo-climatic indicators. Results showed that the RR of the two loess-paleosol sequences had positive, highly significant (P < 0.01) correlations with: 1) citrate-bicarbonate-dithionite (CBD) extracted iron (Fe_d), 2) ratios of CBD extracted iron to total iron (Fe_d/Fe_t), 3) clay (< 2 μm), and 4) magnetic susceptibility (x). This suggested that the RR of these loess-paleosol sequences could indicate degrees of loess weathering and pedogenesis and were potential paleo-climatic proxies. The strong correlations of RR to Fe_d and x also implied that during pedogenic processes, pedogenic hematite in loess and paleosols were closely related to the amount of total secondary iron oxides and pedogenic ferrimagnetic minerals (predominantly maghemite).     

嫩江中下游湿地生态环境敏感性分析及可持续管理对策

对嫩江中下游湿地生态环境从自然驱动因子:流域地形地貌、地质构造和沉积特征、气候变化和人为驱动因子:人类开垦活动、水利工程等条件下进行了敏感性评价,在此基础上提出了湿地生态环境可持续性管理对策。     

与有机物质的分解相关的还原作用对红壤磁性质的影响

Five soils derived from different parent materials were sampled from red soil region of southern China and studied by magnetic methodology to understand to what extent iron reduction would affect soil magnetic properties and how iron reduction would affect the magnetic minerals in soils.Reduction associated with organic matter decomposition strongly affected soil magnetic parameters at low pH.The losses of original soil magnetic signals in terms of magnetic susceptibility(χ),‘Soft’ isothermal remanent magnetization (‘Soft’ IRM),anhysteretic remanent magnetization(ARM) and saturation isothermal remanent magnetization(SIRM) at pH 4-6 during the two-month saturation treatment,were 66%-94%,54%-90%,64%-95% and 33%-83%,respectively.These changes were interpreted as a consequence of substantial dissolution of maghaemite and haematite in the soils.At pH 10,however,there was no significant magnetic change observed.Moreover,stable single domain soil maghaemite grains were also sensitive to reduction,which suggested that both pedogenic and detrital maghaemite were not stable in acid and reducing environments.Goethite,instead,was the most stable iron form under reducing conditions.     

Historical Trace Metal Accumulation in the Sediments of an Urbanized Region of the Lake Champlain Watershed, Burlington, Vermont

This study documents the history ofpollution inputs in the Burlington region of LakeChamplain, Vermont using measurements of anthropogenicmetals (Cu, Zn, Cr, Pb, Cd, and Ag) in four age-datedsediment cores. Sediments record a history ofcontamination in a region and can be used to assessthe changing threat to biota over time and to evaluatethe effectiveness of discharge regulations onanthropogenic inputs.Grain size, magnetic susceptibility, radiometricdating and pollen stratigraphy were combined withtrace metal data to provide an assessment of thehistory of contamination over the last 350 yr inthe Burlington region of Lake Champlain. Magneticsusceptibility was initially used to identify land-usehistory for each site because it is a proxy indicatorof soil erosion. Historical trends in metal inputs inthe Burlington region from the seventeenth through thetwentieth centuries are reflected in downcorevariations in metal concentrations and accumulationrates. Metal concentrations increase above backgroundvalues in the early to mid nineteenth century. Themetal input rate to the sediments increases around1920 and maximum concentrations and accumulation ratesare observed in the late 1960s. Decreases inconcentration and accumulation rate between 1970 andthe present are observed for most metals. Theobserved trends are primarily a function of variationsin anthropogenic inputs and not variations in sedimentgrain size. Grain size data were used to removetexture variations from the metal profiles and resultsshow trends in the anthropogenic metal signals remain. Radiometric dating and pollen stratigraphy providewell-constrained dates for the sediments therebyallowing the metal profiles to be interpreted in termsof land-use history.     

温度对酸性草酸-草酸铵溶液浸提土壤无定形铁的影响

以下蜀黄土为试材,研究温度对酸性草酸-草酸铵缓冲溶液浸提土壤无定形铁的影响。结果表明:随着浸提温度的升高,铁的浸提量明显增加。30℃浸提出的铁约为20℃的1.57倍;而50℃浸提出的铁约为20℃的4.43倍。随温度的升高,浸提后土壤残渣的磁化率迅速降低。20℃浸提后残渣的磁化率值比原样略有减少;30℃浸提后残渣的磁化率约为原样的93.6%;50℃浸提后残渣的磁化率只有原样的65.3%。这说明随着温度的升高,以磁性矿物为代表的结晶态铁也被溶解,浸提出的铁其实已不仅是无定形铁。因此,用酸性草酸铵浸提无定形铁时,严格控制20℃的反应温度十分关键。     

不同环境因子联接方法对崩岗易发性评价的影响

[目的] 研究不同联接方法对崩岗易发性的影响,为区域崩岗的精细化空间预测提供理论依据,进而为合理、经济、高效地做好防灾减灾提供科学支持。[方法] 基于随机森林模型,选择改进频率比(ALSA)与传统频率比(FR)两种不同联接方法,通过地理探测器选取年平均降雨量、年平均降雨侵蚀力、土壤可蚀性、坡长因子、黏粒含量、坡度、砂粒含量、标准化VH通道后向散射系数(表征地表覆被的性质)作为评价指标,以江西省兴国县永丰镇为例开展崩岗易发性评价。[结果] ①ALSA-RF模型较FR-RF模型精度更高,ACC,AUC值分别为83.89%,0.893 0; ②研究区极高、高易发区主要分布于其西南区域,这与实际崩岗分布情况较吻合。[结论] 改进频率比的联接方法较传统频率比方法可以更好地体现区域崩岗的分布规律,可为滑坡研究领域中的类似问题提供借鉴。     

基于贡献率模型的崩塌易发性评价——以广州市白云区为例

[目的] 根据地质灾害野外普查空间数据库,分析花岗岩风化残积土发育地区崩塌形成机理和破坏模式,探究不同环境孕灾因子对崩塌发育的贡献率,评估崩塌灾害空间易发性与分布规律,为中国东南沿海地质灾害多发区的灾害防治工作提供科学支持。[方法] 在分析广州市白云区花岗岩风化残积土崩塌发育特征的基础上,选取高程、坡度、坡向、地形起伏度、距地表水体距离、降雨量、地层岩性、土地利用类型共8个与崩塌灾害发育密切关联的致灾因子构建崩塌灾害易发性评价指标体系,叠加研究区内404个历史崩塌数据,依据贡献率模型计算统计各指标因子崩塌灾害敏感性和空间分布特征。采用各二级指标因子贡献率的修正样本差确定因子权重。[结果] ①研究区内坡度、高程和地形起伏度对崩塌易发性贡献程度较高,坡向、地层岩性、降雨量在崩塌灾害易发性评价中贡献程度较低。②极高易发区主要集中在丘陵西麓,崩塌易发性由山地线范围外层边缘向中心逐级降低。③崩塌极高易发区和高易发区崩塌比率占总崩塌比率超过85%,模型易发性评价成功率和预测率分别达到91.3%和92.6%。[结论] 斜坡地形地貌因子对崩塌发育影响较显著,基于贡献率的崩塌灾害易发性评价模型能够客观量化指标因子权重,模型预测评价结果精度较高,易发性区划符合实际崩塌发育空间分布特征。     

Drought as a modulator of plant–virus–vector interactions: Effects on symptom expression,plant immunity and vector behaviour

Plant–virus interactions are affected by environmental conditions that determine plant vulnerability to pathogens and the population dynamics of insect vectors. We hypothesize that drought enhances horizontal transmission by dampening the basal immunity of plants, which triggers symptom expression and vector manipulation. The potato yellow vein virus (PYVV) causes potato yellow vein disease (PYVD), a re-emerging epidemic of potato crops in South America, and is transmitted horizontally by the greenhouse whitefly (GWF), Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), or vertically through infected seed tubers. We investigated the role of drought and temperature as modulators of PYVD symptom expression, plant immune response, and vector survival, development and host preference. We found that drought induced symptom expression, suppressed the salicylic acid pathway and increased PYVV replication. GWF survival was reduced on PYVV-infected hosts and development was slowest when they fed on plants with PYVD symptoms, which also triggered adults’ attraction to PYVV-infected plants. However, adults previously fed on infected plants showed the opposite effect, being more attracted to PYVV-free plants. We propose a theoretical model that explains the role of drought in modulating potato–PYVV–GWF interactions and provides new insights into plant–virus–vector coevolution.     

实验猴志贺氏菌检出、血清分型及药物敏感性试验

采用实验动物国家标准(GB/T 14926.47-2001)的检验方法,对144份待出口实验猴粪便样品检测,检出志贺氏菌2株,阳性检出率1.39%。血清学分型,均属于B群志贺氏菌,血清型分别为X变种和Y变种。药敏试验结果表明,2株分离菌对先锋V、氟哌酸和环丙沙星高度敏感,而对青霉素、红霉素和复方新诺明耐药。