抗羟脯氨酸水稻变异系的筛选及其特性的研究

利用Hyp反复筛选经EMS处理的水稻愈伤组织,得到4个抗性细胞系。它们的游离脯氨酸含量高于对照2—25倍。Hyp(2 mmol/L)和NaCl(1%)胁迫对M_1、M_2变异系γ-谷氨酰磷酸合成活力及游离脯氨酸积累的影响呈一定的正相关性。变异系在0.8%,15NaCl 培养基中分化出植株。与对照相比,各变异系在愈伤组织、植株水平上均表现较强的耐盐性,且与游离脯氨酸的积累量呈正相关。     

耐盐突变体小麦后代耐盐稳定性分析研究

以卫星搭载小麦种子为原始材料,利用其幼穗、幼胚诱导的愈伤组织进行耐盐突变体的筛选,对耐盐愈伤组织再生植株后代进行耐盐稳定性生理生化特性分析。结果表明：(1)耐盐系后代在土壤高盐浓度条件下,游离脯氨酸含量稳定增加,且高于对照系;(2)耐盐系再生植株后代保持较高的K^ ／Na^ 比;(3)与对照相比,种子醇溶蛋白电泳带谱中的b2,b3,b5,b7带为耐盐系所特有,b8带消失;(4)耐盐系再生植株后代可溶蛋白电泳带为26条,而对照系为23条蛋白带。其中98kD、75kD、52kD、49kD和32kD为耐盐系的特有蛋白带。而38kD和35kD蛋白带为对照系所特有。     

水稻高脯氨酸愈伤组织变异体的选择及其耐盐性

以水稻（ＯｒｙｚａｓａｔｉｖａＬ．）品种双丰１号幼胚愈伤组织为材料,经５０ＣＯγ－射线诱变处理后,用羟基脯氨酸（Ｈｙｐ）作为选择压力,通过多次在含Ｈｙｐ（３．０ｍｍｏｌ／Ｌ）的选择培养基和无Ｈｙｐ培养基上交替培养,分离出耐Ｈｙｐ的愈伤组织变异体。该变异体以高脯氨酸含量为特征,其脯氨酸含量比原型高２．６倍;在ＮａＣｌ处理时,随着ＮａＣｌ浓度的提高,变异体愈伤组织脯氨酸含量的增加大大高于原型。这种高脯氨酸变异体的耐盐性较原型强,用相对鲜重估计其耐性比对照提高３９％。变异体在盐胁迫下可溶性糖含量比原型多,吸收较多的Ｎａ＋,并维持较高的Ｋ＋含量;但Ｋ＋／Ｎａ＋比与原型无差异。变异体含水量略有下降。这些性状的变化显示了变异体在盐胁迫下渗透调节的加强。     

高粱不同类型胚性和非胚性愈伤组织的生理生化差异

植物体细胞胚胎发生过程中伴随着复杂的生理生化变化,为进一步揭示胚性愈伤组织的再生潜力,该研究以高粱Sb19未成熟胚诱导产生的两种胚性愈伤组织和一种非胚性愈伤组织为材料,通过测定各愈伤组织中可溶性蛋白、游离脯氨酸和可溶性糖的含量,采用方差分析法对高粱体细胞胚胎发生过程中不同类型愈伤组织的生理生化指标进行了差异比较研究。结果表明:(1)高粱两种胚性愈伤组织中可溶性蛋白、游离脯氨酸和可溶性糖的含量均显著高于非胚性愈伤组织,表明胚性愈伤组织中的代谢活性高于非胚性愈伤组织,能够为体细胞胚胎发生提供更多的物质能量基础。(2)两种类型胚性愈伤组织之间生理生化差异显著,其中,Ⅱ型胚性愈伤组织中可溶性蛋白和游离脯氨酸含量均显著高于Ⅰ型胚性愈伤组织,相反,Ⅱ型胚性愈伤组织中可溶性糖含量显著低于Ⅰ型胚性愈伤组织,这种生理生化差异在一定程度上影响了后期的分化。该研究结果为愈伤组织的胚胎发生能力与生化代谢的关系提供理论依据。     

单倍性烟草Hyp抗性愈伤组织变异系的选择及其生理生化特性的研究Ⅱ．Hyp抗性变异系内游离脯氨酸的积累

在正常条件下,烟草Hyp抗性变异系愈伤组织内的游离脯氨酸含量是其野生型的4倍多。这种积累游离脯氨酸的特性在愈伤组织的转代、再生及次生过程中均十分稳定。虽然其他多种氨基酸含量也有所改变,但变异系内游离脯氨酸的积累具有特异性。由于脯氨酸对Hyp抑制效应具有部分的逆转作用,所以游离脯氨酸的积累是变异系抗Hyp抑制作用的重要原因。然而,变异系内蛋白质组成中的脯氨酸并没有特异性地增加。在Hyp存在条件下,变异系内的硝酸还原酶、转化酶及过氧化氢酶活性均显著地高于野生型。表明变异系对培养基中的碳源和氮源具有较高的利用能力。     

枸杞耐盐变异体的筛选及植株再生

枸杞(Lycium barbarum L.)无菌苗下胚轴于MS+2,4-D 0.25mg/L+LH 50 0mg/L的诱导培养基上产生胚性愈伤组织。经0.34%的EMS(半致死剂量)处理并恢复增殖2周后, 将存活组织转接到含有1.5%NaCl的诱导培养基上培养4周,再将少数存活的组织转移到含1.0%NaCl的同样培养基上继续培养,经不断选择,选出了耐1.0%NaCl的愈伤组织变异体。经耐盐性、耐盐稳定性、脯氨酸含量、叶绿素含量分析,以及对山梨醇、聚乙二醇的反应证明,该愈伤组织是耐盐变异体。变异体在含有1.0%NaCl的分化培养基(MS+6-BA0.5mg/L)上可分化出再生植株。     

葡萄耐羟脯氨酸变异细胞系的筛选及其特性研究（简报）

葡萄愈伤组织经甲基磺酸乙酯（EMS）诱变处理后,用羟脯氨酸（HMP）作为选择压力,筛选出耐HYP的变异细胞系。该变异系游离脯氨酸含量比正常细胞系高4．7倍,并且表现出很强的耐NaCl和PEG能力。在盐胁迫下,变异系吸收的K 和Na 含量均高于正常系,而K ／Na 比值仍与正常系相近。     

枸杞耐盐突变体的筛选及生理生化分析

用不同剂量60Coγ对以枸杞叶为外植体诱导出的愈伤组织进行辐射处理,并将恢复增殖的愈伤组织采用逐步提高盐浓度的方法,直到筛选出耐1%的愈伤组织变异体,通过对其生理生化的分析表明:变异体在不同盐浓度胁迫下干、鲜重增长均高于对照组;MDA含量和质膜透性、O-·2与H2O2含量都低于对照组;抗氧化酶SOD、POD、CAT活性均高于对照组;对可溶性蛋白SDS电泳结果表明:耐盐变异体有22条蛋白带,而对照组有21条蛋白带,其中31.3kD、21.0kD、18.5kD带为耐盐变异体所特有,而74.1kD、52.1kD带为对照组所特有,并且73.7kD、67.9kD的蛋白耐盐变异体含量高于对照组.     

单倍性烟草Hyp抗性愈伤组织变异系的选择及其生理生化特性的研究I．Hyp抗性变异系的抗性表现

利用多步正筛选系统,对⁶⁰C0Y射线诱变的单倍性体细胞愈伤组织无性系经过连续八轮的分离与选择,获得了抗脯氨酸类似物Hyp(L－羟基脯氨酸)的烟草愈伤组织变异系C^r-2,H^r-4和X^r-1,并由之再生出了相应的抗性植株。离开选择压力的Hyp抗性变异体愈伤组织系、再生植株及其次生愈伤组织均具抗Hyp的抑制作用。变异系对苏氨酸的抑制作用不表现交叉抗性。在Hyp抑制培养基上,变异体小植株的发根能力高于其野生型。离开选择剂转代培养了七代的变异系对Hyp的抑制作用仍保持着相对稳定的抗性。     

提高水稻组培诱导频率方法及其对耐冷变异体筛选的研究

本试验得到外植体种胚的适宜接种量为6粒左右,培养基量为15—20毫升。由于不同品种具有的基因型各异,因而接种的外植体成熟胚和幼穗离体培养的愈伤组织诱导与分化率也有所不同。在Ms培养基中NAA的适宜浓度为2mg/L,附加一定量的酵母膏有提高分化率的趋势。 从560份耐冷变异体株系中,经生理生化测定和田间鉴定,初步认为耐冷变异体有三份:647—4;160—3—1;和160—4。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。