薇甘菊的化感作用研究

研究薇甘菊对萝卜、黑麦草、白三叶以及薇甘菊常见伴生树种马占相思、马尾松、大叶桉的生化他感作用。分别用薇甘菊地上部分、根部、枯枝叶和土壤的水提液以及地上部分的石油醚、乙酸乙酯和乙醇提取液按照一定浓度进行生物测定。研究表明,薇甘菊地上部分水提液能够显著影响受体植物生长,根水提液的抑制作用程度稍低,其枯枝叶水提液基本无作用。薇甘菊地上部分的石油醚和乙醇提取物均对受体植物幼苗生长表现出一定的抑制作用．但是乙酸乙酯提取物的作用最强烈,可使种子发芽过程受阻,幼苗生长受抑制程度高达90％以上．显示化感物质主要集中在这一部分。     

果胶酶制剂中花色素酶的去除

以皂土为吸附剂,将花色素酶从粗果胶酶制剂中除去。分离效果受pH和皂土用量影响。皂土还具有一定的脱色作用。黑曲霉AS3.316麦麸固体曲用5倍重量的自来水于室温下抽提4小时。粗果胶酶拙提液中加入3％皂土,调pH至4.1,于室温下放置30分钟。过滤所得部分提纯酶液含果胶酶258u/ml,酶活力回收为88％。 100ml山楂汁和387u(1.5ml)上述部分提纯的果胶酶于50℃保温3小时后,澄清度由65％提高到98％;相对粘度由12.5下降到1.2;果胶完全水解;红色素完全保留着。     

黄河流域棉区转Bt基因棉种植对根际土壤微生物数量及细菌多样性的影响

采用传统培养与PCR-DGGE相结合的方法研究了黄河流域棉区4个省份种植的转Bt基因棉在4个生长时期（播种后第30天、第60天、第90天和第120天）的根际土壤微生物数量及细菌多样性.结果表明：同一省份同一生长时期转Bt基因棉根际土壤微生物数量与常规棉相比均无显著差异,其数量主要受不同生长时期影响,而不同省份间主要受地域条件的影响.4个省份转Bt基因棉根际土壤细菌多样性较丰富,同一省份同一生长时期内转Bt基因棉与常规棉根际土壤细菌多样性指数、均匀度和丰富度均无显著差异.不同省份间细菌多样性主要因地域条件而有所不同,但差异较小.     

1954—2005年中国北方针叶林分布区的气候变化特征

基于中国北方针叶林(兴安落叶松林)分布区8个气象观测站的气象资料,分析了1954—2005年气温和降水的变化特征.结果表明：研究期间,中国北方针叶林分布区的气温以0.38 ℃·(10 a)^-1的速度上升,远大于全球近50年来0.13 ℃·(10 a)^-1的平均增温速率.尽管夏、秋季的气温呈上升趋势,但不显著;而冬、春季的增温显著(P<0.01);最高年平均气温(0.37 ℃·(10 a)^-1)与最低年平均气温(0.54 ℃·(10 a)^-1)均呈极显著的增加趋势(P<0.01).降水量年际间波动较大,但没有明显的变化趋势;各季节降水量也没有明显的变化规律,其中春、秋、冬季的降水日数有增加趋势,但没有达到显著水平,而夏季的降水日数呈显著减少趋势(P<0.05);各季降水强度均呈增加趋势,其中夏季(P<0.05)和冬季(P<0.01)的变化达到了显著水平.     

不同密度下沙地樟子松碳、氮、磷化学计量及养分重吸收特征

以樟子松纯林为对象,研究了6种密度(490、750、1110、1550、1930、2560株.hm-2)下不同器官(当年生叶、一年生叶、当年生枝、一年生枝和细根)的C、N、P化学计量特征及叶片N、P重吸收效率.结果表明:随着林分密度增加,当年生和一年生叶C含量及当年生和一年生枝P含量呈降低趋势(1550株.hm-2除外...     

Association of Childhood Economic Hardship with Adult Height and Adult Adiposity among Hispanics/Latinos. The HCHS/SOL Socio-Cultural Ancillary Study

The study examined the association of childhood and current economic hardship with anthropometric indices in Hispanic/Latino adults, using data from the HCHS/SOL Socio-cultural ancillary study (N = 5,084), a community-based study of Hispanic/Latinos living in four urban areas (Bronx, NY, Chicago, IL, Miami, FL, and San Diego, CA). Childhood economic hardship was defined as having experienced a period of time when one’s family had trouble paying for basic needs (e.g., food, housing), and when this economic hardship occurred: between 0–12, 13–18 years old, or throughout both of those times. Current economic hardship was defined as experiencing trouble paying for basic needs during the past 12 months. Anthropometry included height, body mass index (BMI), waist circumference (WC), and percentage body fat (%BF). Complex survey linear regression models were used to test the associations of childhood economic hardship with adult anthropometric indices, adjusting for potential confounders (e.g., age, sex, Hispanic background). Childhood economic hardship varied by Hispanic background, place of birth, and adult socio-economic status. Childhood economic hardship during both periods, childhood and adolescence, was associated with shorter height. Childhood economic hardship was associated with greater adiposity among US born individuals only. Current economic hardship was significantly associated with all three measures of adiposity (BMI, WC, %BF). These findings suggest that previous periods of childhood economic hardship appear to influence adult height more than adiposity, whereas current economic hardship may be a better determinant of adult adiposity in Hispanics.     

Systematic implications of seed coat diversity in Gaultherieae (Ericaceae)

The seed morphology of 90 samples from 83 species of tribe Gaultherieae (Chamaedaphne, Diplycosia, Eubotryoides, Eubotrys, Gaultheria and Leucothoe) and relatives in tribes Andromedeae (Andromeda and Zenobia) and Vaccinieae (Satyria) was investigated with stereoscopic and scanning electron microscopy. Seeds exhibit variation in shape, colour, size, wing, hilum region, primary ornamentation and epidermal cells. Non‐metric multidimensional scaling (NMDS) analysis based on selected seed characters supports the affinities of some groups within Gaultherieae at various taxonomic levels. Seed characters corroborate the delimitation of Andromeda, Chamaedaphne, Leucothoe, Satyria and Zenobia and Gaultheria series Trichophyllae, series Hispidulae, section Amblyandra and section Brossaeopsis. Parsimony optimization of seed characters onto a previously published phylogenetic estimate of Gaultherieae reveals that small seeds have evolved from larger seeds and an areolate seed coat has evolved from a reticulate seed coat. Optimization also suggests that several seed character states are synapomorphies or potential synapomorphies for some major clades of Gaultherieae. Seeds of Gaultherieae from East Asia, temperate North America and the Pacific are more diverse than those from tropical America. Samples from the eastern Himalaya possess the highest variation in seed morphology. The wing and bulging edge cells observed in seeds of Leucothoe suggest dispersal by wind. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 477–495.     

陕西省主要蔬菜产区蔬菜重金属污染状况分析与评价

以GB18406．1-2001无公害蔬菜标准为评价依据．对陕西省8个蔬菜主产区的127个蔬菜样品中汞、砷、铅、镉和铬5种重金属污染状况进行分析评价。结果表明,陕西省主要蔬菜产区蔬菜重金属污染以铅污染为主。茄果类和瓜菜类蔬菜铅污染严重,绿叶类蔬菜铅污染相对较轻．其它4种重金属污染未超过国家标准,其中各产区均未检出镉。铅污染程度的大小顺序足成阳秦都〉宝鸡岐山蔡家坡〉汉中汉台〉渭南临渭。成阳泾阳、宝鸡太白、汉中城固、渭南大荔蔬菜产区5种蓖金瞒均未超标．具备发展无公害蔬菜生产基地条件。     

Quaternary structure of <Emphasis Type="Italic">Artemia</Emphasis> haemoglobin II: analysis of T and C polymer alignment and interpolymer interface

Background  

The brine shrimp Artemia expresses four different types of haemoglobin subunits namely C1, C2, T1 and T2. Two of these four subunits dimerize in different combinations to produce the three isoforms of the heterodimeric Artemia haemoglobin: HbI (C1 and C2), HbII (C1 and T2) and HbIII (T1 and T2). Previous biochemical, biophysical and computational analyses demonstrate that the T and C polymers are rings of nine concatenated globin domains, which are covalently joined by interdomain linkers. Two such rings stacked coaxially give the functional molecule. This research aimed to construct a quaternary structural model of Artemia HbII that shows the interpolymer interface and domain-domain alignment, using the MS3D (mass spectrometry for three dimensional analysis) approach. This involved introducing chemical crosslinks between the two polymers, cleaving with trypsin and analyzing the resulting products by mass spectrometry. This was followed by computational analysis of the mass spectrometry data using the program SearchXlinks to identify putatively crosslinked peptides.     

Natural variation of salinity response,population structure and candidate genes associated with salinity tolerance in perennial ryegrass accessions

Natural variation in salinity response, effects of population structure on growth and physiological traits and gene–trait association were examined in 56 global collections of diverse perennial ryegrass (Lolium perenne L.) accessions. Three population structure groups were identified with 66 simple sequence repeat markers, which on average accounted for 9 and 11% of phenotypic variation for the control and salinity treatment at 300 mm NaCl. Group 1 (10 accessions) had greater plant height, leaf dry weight and water content, chlorophyll index, K⁺ concentration and K⁺/Na⁺ than group 2 (39 accessions) and group 3 (7 accessions) under salinity stress, while group 3 had higher Na⁺ than groups 1 and 2. Eighty‐seven single nucleotide polymorphisms were detected from four partial candidate genes encoding aquaporin and Na⁺/H⁺ antiporter in both plasma and tonoplast membranes. Overall, rapid decay of linkage disequilibrium was observed within 500 bp. Significant associations were found between the putative LpTIP1 and Na⁺ for the control and between the putative LpNHX1 and K⁺/Na⁺ under the control and salinity treatments after controlling population structure. These results indicate that population structure influenced phenotypic traits, and allelic variation in LpNHX1 may affect salinity tolerance of perennial ryegrass.