^14—菲在营养液—火山石—小麦有控系统中的迁移和转化

利用放射性同位素示踪技术研究了＾１４Ｃ标记菲在有控系统中的迁移转化,结果表明,＾１４Ｃ－菲在有控降解较快,施入药品２４ｄ后仅有０．３２％的＾１４－菲存留在植物、营养液和火山石中,植物吸收的＾１４Ｃ放射性大部分被结合植物组织中,其它＾１４Ｃ主要以菲的极性代谢物形态存在。     

~(14)C-菲在营养液-火山石-小麦有控系统中的迁移和转化

利用放射性同位素示踪技术研究了１４Ｃ标记菲在有控系统中的迁移转化．结果表明,１４Ｃ菲在有控系统中降解较快,施入药品２４ｄ后仅有０．３２％的１４Ｃ－菲存留在植物、营养液和火山石中．植物吸收的１４Ｃ放射性大部分被结合到植物组织中,其它１４Ｃ主要以菲的极性代谢物形态存在．     

~(14)-C菲在“植物-火山石-营养液-空气”系统中的迁移和转化

利用放射性同位素示踪技术 ,研究14 C 菲在“植物 火山石 营养液 空气”封闭系统中的迁移转化 .结果表明 ,菲在该系统中降解较快 ,实验进行到 2 3d时 ,营养液中的放射性含量仅为施入时的 2 5 % .实验结束 (46d)时 ,14 C放射性在该系统各部分间的分布顺序为根 (38.5 5 % ) >挥发性有机代谢产物 (VOCs ,17.6 8% ) >火山石(14 .35 % ) >CO2 (11.42 % ) >茎 (2 % ) ;植物体内的放射性物质主要以结合态 (根 4.6 8% ;茎叶 0 .6 8% )与植物组织结合和以极性代谢产物 (根 2 3 .14 % ;茎 0 .78% )形式存在 .     

^14C—菲在“植物—火山石—营养液—空气”系统中的迁移和转化

利用放射性同位素示踪技术,研究^14C－菲在“植物－火山石－营养液－空气”封闭系统中的迁移转化。结果表明,菲在该系统中降解较快,实验进行到23d时,营养液中的放射性含量仅为施入时的25％,实验结束（46d）时,^14C放射性在该系统各部分间的分布顺序为根（38.55%）＞挥发性有机代谢产物（VOCs,17.68%）＞火山石（14.35%）＞CO2（11.42%0＞茎（2％）;植物体内的放射性物质主要以结合态（根4.68%,茎叶0.68%）与植物组织结合和以极性代谢产物（根23.14%;茎0.78%）形式存在。     

14C-涕灭威在旱田土壤中的降解

研究了¹⁴C-涕灭威在5种土壤中(4ppm,1.22μCi·50g^-1 土壤干重)的生物降解。模拟试验为密闭系统,土壤中水分含量为22%,气温20-30℃在供试的5种土壤中,北京肖家河的土壤降解最快,为施人放射剂量的51.3%,以“¹⁴CO₂ 形式从土壤进出;26.0%与土壤结合,只有21.6%可以被抽出。取自浙江义乌的土壤降解较慢,收集到的¹⁴CO₂ 为施入量的23.3%.土壤中加入杀菌剂红霉素或敌茵丹降解作用明显减慢。土壤提取物中涕灭威亚砜、涕灭威亚砜肟被确认是主要的代谢产物,还发现了少量的涕灭威砜,涕灭威亚砜腈涕灭威砜腈和涕灭威砜肟等降解物。     

FGF14在神经退行疾病中的研究进展 *

成纤维细胞生长因子14(FGF14)是成纤维细胞生长因子家族中一员,主要在发育中及成熟的神经系统中表达。研究发现,FGF14在退行性神经系统中的脊髓小脑共济失调27型中发挥着重要的作用,FGF14的功能与各种离子通道关系密切,以钠离子通道为主,活性被神经元的兴奋性调节。根据FGF14的特点,归纳总结了FGF14目前的研究进展,为FGF14的基础和工程化研究提供理论依据。     

高温胁迫对14C-水杨酸在葡萄苗中运转分配的影响

用38℃高温和27℃正常温度分别处理14C-SA标记的葡萄幼苗叶片1,3,6,12h,发现常温下14C-SA向外运转的很少,而高温下向外运转的更少。高温处 理和常温对照的14C-SA都既向上运输又向下运输,以向下运输为主,但无论向上运输还是向下运输,高温下要比常温下运输的少一些。在常温下1,3,6h,14C-SA 以根系分配的最多,12h以茎中分配最多,而在高温处理下1,3h以根中分配最多,6,12h则以茎中分配最多。高温处理和常温对照下都是离引入叶越近的茎 段和叶片(除引入叶),14C-SA含量越高。     

FITC示踪在优化小麦花粉管通道转化方法中的应用

利用FITC(fluorescein is othiocyanate,异硫氰酸荧光素)标记的外源DNA对小麦进行了花粉管通道法转化,在荧光显微镜下观察了外源DNA进入小麦胚囊的情况,并初步研究了转化时间及转化溶液组成对DNA进入胚囊效率的影响。结果表明,外源DNA沿着花粉管生长过程中形成的花粉管通道进入胚囊;授粉45 min和60min进行转化外源DNA进入胚囊的几率较大,因此在此段时间开始转化较为合适;相对于TE缓冲液,将0.05%Silwet L-77和5%蔗糖作为转化溶液可以缩短DNA进入胚囊的时间,但不能提高外源DNA进入胚囊的几率。研究表明,使用FITC标记观察外源DNA进入胚囊效率的方法,可简便有效地应用于花粉管通道法转化条件的初步优化。     

DKK-1和MMP-14在口腔鳞癌中的表达及其意义

目的:研究DKK-1蛋白和MMP-14蛋白在口腔鳞状细胞癌组织中的表达和临床意义。方法:选择口腔鳞癌石蜡标本62例作为实验组,25例正常口腔黏膜组织作为对照组。应用免疫组织化学法检测其DKK-1和MMP-14蛋白的表达,并分析二者与口腔鳞癌患者临床病理特征之间的关系及二者表达的相关性。结果:实验组DKK-1的阳性表达率为40.32%,明显低于对照组中(68%),而MMP-14的阳性表达率(72.58%)明显高于对照组(24%)(P0.05)。DKK-1和MMP-14的表达水平与口腔鳞癌的分期、淋巴结转移及分化程度有显著相关(P0.05)。口腔鳞癌组织中DKK-1和MMP-14蛋白的表达呈显著负相关(r=-0.600,P0.05)。结论:口腔鳞状细胞癌组织中DKK-1的表达下调,MMP-14的表达上调,二者可能参与了OSCC的发生和发展过程,并有望用于口腔鳞状细胞癌的病情和预后评估。     

抑制剂及其组合对尿素15N在小麦土壤系统中的行为和归宿的影响

应用加有脲酶抑制剂(HQ)、硝化抑制剂(DCD)及其组合的标记尿素进行春小麦盆栽试验.结果表明,在生长季节结束时,小麦回收,土壤残留和损失的肥料N各占施入N量的17.65～23.69%、43.72～56.32%和19.99～36.77%.其中,与单施尿素相比,两种抑制剂配合使用处理的肥料N总回收率高16.78%,小麦回收高5.96%.施用氮肥对籽粒贡献最大,占吸收肥料N量43.3～62.0%.     

A comparison of a tissue solubilization method with a combustion method for liquid scintillation counting of14C-labelled soil

Summary A comparison between a tissue solubilization method and a sample oxidizer technique to measure¹⁴C in plant and soil material is described. The solubilization method although not quantitative gives good recoveries and reproducible values of¹⁴C-content with soil samples not exceeding 10 mg and should be of value for estimating the¹⁴C-content of soils in laboratories without a sample oxidizer.     

14C-Metabolism in cultured cotyledon explants of radiata pine

Excised cotyledons of radiata pine ( Pinus radiata D. Don), cultured under shootforming (plus cytokinin) and elongating (minus cytokinin) conditions, were incubated in ¹⁴C-glucose, ¹⁴C-acetate or ¹⁴C-bicarbonate at different stages of growth and differentiation. ¹⁴CO₂ was produced when the cotyledons were fed ¹⁴C-glucose and ¹⁴C-acetate (no measurement was made for ¹⁴C-bicarbonate feeding). Label from these precursors was incorporated into ethanol-soluble and -insoluble fractions. The largest percentage of radioactivity was associated with the ethanol-soluble portion, which was further fractionated into lipids, amino acids, organic acids and sugars. The amount of label and the pattern of labelling associated with each of the above classes of metabolites varied with time in culture and morphogenetic behaviour of the cotyledons. In general, there was a tendency towards a high rate of incorporation of label in elongating cotyledons during the period of rapid elongation. On the other hand, a high rate of incorporation of label in shoot-forming cotyledons coincided with the period of meristematic tissue formation. The data obtained support the hypothesis that organized development in vitro involves a shift in metabolism, which precedes and is coincident with the initiation of the process.     

The effect of water status and season on the incorporation of 14CO2 and [14C]-acetate into resin and rubber fractions in guayule

The effects of drought stress and season on both allocation of photosynthates to stems and leaves and potential for stem rubber synthesis were studied in guayule ( Parthenium argentatum Gray USDA line 11604). Two-year-old plants grown under field conditions in the Negev desert of Israel were subjected to different irrigation regimes, and water status was assessed by measuring the relative water content (RWC). Undetached plant tips were exposed to a 1 h pulse of ¹⁴CO₂, followed by a 24 h chase. ¹⁴C fixed and translocated to different plants parts and notably ¹⁴C incorporation into rubber and resin fractions was determined. The potential of detached branch slices to incorporate [¹⁴C]-acetate into rubber was also studied. A higher percentage of fixed ¹⁴C was translocated from shoot tips in winter (28–30%) than in summer (15–18%). The percentage of [¹⁴C]-acctate incorporated into the rubber fraction by stem slices was maximal in winter (20%) and minimal in summer (3–5%) in both cases in the absence of drought stress. In summer the translocation of photosynthates into stems was inversely related to plant RWC, dropping from 18% three days after irrigation to 3% 14 days later, and the potential of stems to synthesise rubber was high under drought conditions and low in well irrigated plants.     

Heterogeneous distribution of phosphorus and potassium in soil influences wheat growth and nutrient uptake

Heterogeneous distribution of mineral nutrients in soil profiles is a norm in agricultural lands, but its influence on nutrient uptake and crop growth is poorly documented. In this study, we examined the effects of varying phosphorus (P) and potassium (K) distribution on plant growth and nutrient uptake by wheat (Triticum aestivum L.) grown in a layered or split soil culture in glasshouse conditions. In the layered pot system the upper soil was supplied with P and either kept watered or allowed to dry or left P-deficient but watered, whereas the lower soil was watered and fertilised with K. Greater reductions in shoot growth, root length and dry weight in the upper soil layer occurred in −P/wet than in +P/dry upper soil treatment. Shoot P concentration and total P content were reduced by P deficiency but not by upper soil drying. Genotypic responses showed that K-efficient cv. Nyabing grew better and took up more P and K than K-inefficient cv. Gutha in well-watered condition, but the differences decreased when the upper soil layer was dry. In the split-root system, shoot dry weight and shoot P and K contents were similar when P and K were applied together in one compartment or separated into two compartments. In comparison, root growth was stimulated and plants took up more P and K in the treatment with the two nutrients supplied together compared with the treatment in which the two nutrients were separated. Roots proliferated in the compartment applied with either P or K at the expense of root growth in the adjoining compartment with neither P nor K. Heterogeneous nutrient distribution has a direct decreasing effect on root growth in deficient patches, and nutrient redistribution within the plant is unlikely to meet the demand of roots grown in such patches.     

Acetylation of wheat straw hemicellulose B in a new non-aqueous swelling system

The acetylation of wheat straw hemicellulose B was carried out in a homogeneous N,N-dimethylformamide and lithium chloride system with acetic anhydride using 4-dimethylaminopyridine as a catalyst. The degree of substitution of hemicellulose B acetates ranged between 0.59 and 1.25 as a function of experimental conditions. Under an optimum condition (85°C, 60 h), approximately 75% of the free hydroxyl groups in native hemicellulose B were acetylated. The molecular weight measurements (31,890–34,090 g mol⁻¹) showed a controllable degradation of hemicellulose B chains during the reactions at temperature 60–85°C and duration of 2–60 h. It was found that the thermal stability of the products was increased by chemical modification.     

小麦/大豆间作中作物种间的竞争作用和促进作用

春小麦／春大豆间作是西北一熟制灌区广泛采用的高产种植形式．本文采用田间小区和微区根系分隔试验研究了这种种植形式作物种间的竞争作用和促进作用．结果表明,小麦／大豆间作具有明显的间作优势．土地当量比为１．２３～１．２６．小麦为优势种,竞争力强于大豆,具有明显的间作边行优势．小麦边行优势的１／３贡献来自于地下部．小麦收获后,大豆生长具有恢复作用,认为这种恢复作用是间作优势的机制之一．间作相对于单作两种作物的收获指数均有显著提高．收获指数的种间促进作用是间作优势的另一机制．