华北平原罗布麻种群生殖分株数量特征及变化规律

通过大样本取样调查,研究了华北平原罗布麻种群生殖分株的数量特征和生殖分配规律．结果表明,在籽粒完熟期,罗布麻种群单个生殖分株重为10．38±7．78g,蒴果生物量和蒴果数分别为1．57±1．59g和7．60±6．56个;种子生物量和种子数分别为0．34±0．33g和582．3±558．7个;生殖分配Ⅰ和生殖分配Ⅱ分别为12．98±7．94和2．75±1．69％．蒴果和种子形成分别需要分株积累1．42和1．77g以上的生物量．蒴果生物量、葫果数、种子生物量、种子数分别与分株总生物量呈极显著的（P〈0．01）线性正相关关系;蒴果数、种子数与茎叶生物量分配呈极显著的（P〈0．01）线性负相关关系;生殖分配Ⅰ、生殖分配Ⅱ和叶生物量分配呈极显著的（P〈0．01）线性负相关关系．单葫果的重量、种子重、种子数、种子毛重、胎座重分别和葫果的长度呈极显著（P〈0．01）的幂函数正相关关系．罗布麻种群生殖分株同时具有同速和异速2种不同增减过程的表型可塑性调节．     

葎草种群自疏过程中幼苗构件性状及生物量分配变化

以雌雄异株攀援草本植物葎草为材料,通过每10 d测量1次,连续6次,测定幼苗期葎草种群的密度和高度、个体构件性状和生物量分配等参数,分析种群自疏过程中种群密度与个体构件性状及生物量分配的关系,研究葎草种群的自疏规律。结果表明:幼苗期葎草种群存在显著的自疏现象,种群密度60 d内下降了71%;幼苗期葎草由直立生长向横向生长时,种群密度和株高显著降低;自疏过程中存留植株的茎性状有显著变化,变化大小为节间长主茎长茎直径,节间长增加,叶性状变化大小为叶面积叶柄长叶厚叶宽叶长总叶数保留叶片数,根性状变化大小为总根长根体积根数根长最大根长;自疏过程中存留植株的构件生物量、单株生物量显著增加,而单位面积累积生物量呈阶段性下降;留存植株的地上生物量分配比相对稳定(P0.05),根茎比和叶茎比有极显著变化(P0.01);叶、茎、叶柄生物量与根生物量和地上生物量之间均呈极显著的异速关系(P0.01),茎随地上生物量增长呈等速生长,而叶、叶柄和根随地上生物量增长呈异速生长,地上生物量与叶、茎、叶柄及根生物量极显著相关(P0.01);茎生物量与密度的异速关系遵循最终产量恒定法则,叶、叶柄和根生物量并不满足-3/2或-4/3或-1自疏法则;地上和单株总生物量与密度极显著相关(P0.01),存留单株的地上生物量和总生物量与密度的异速关系遵循最终产量恒定法则。     

安徽大龙山国家森林公园东亚小金发藓配子体与孢子体个体性状及其相互关系

植物性状是植物对环境变化响应和适应的综合反映。目前对苔藓植物个体水平功能性状的研究较为匮乏。以安徽大龙山国家森林公园分布的东亚小金发藓（Pogonatum inflexum）雌株为例,在其孢子体成熟期测定地上部分孢子体和配子体的形态特征及生物量,系统分析了植株性状变异特征、异速生长关系及协变（整合）格局。结果表明,东亚小金发藓配子体形态性状变异性高于孢子体,且二者生物量变异系数最大。孢子体高度是配子体的2倍,但其生物量仅占地上部分的23%。孢子体和配子体功能性状之间有一定相关性;形态性状（Y）与生物量（X）之间多为指数<1.0异速生长关系,而孢子体和配子体生物量之间为等速生长关系（指数为1.135±0.158）。孢子体生物量分配比例随个体增大而显著减小,体现出显著的负的个体大小依赖。主成分分析表明,东亚小金发藓孢子体和配子体主要个体性状具有不同的协变方向（即两个不同的性状群）,其中孢子体生物量是两类性状群的关键结点。综合来看,东亚小金发藓个体性状间具有与维管植物相似的协变关系。     

大豆作物响应增强UV—B辐射的品种差异

田间条件下模拟20％平流层臭氧层衰减,紫外线（UV－B,280－315nm)辐射增强,研究了UV－B对2个大豆（Glycin max (L.)Merr.)品种黑豆和晋豆生长,光合作用和稳定碳同位素组成的影响,结果表明,晋豆比黑豆对UV－B有较强的抗性或不敏感,表现为增强的UV－B辐射显著抑制黑豆的生长和株高,叶、茎、根和总生物量以及株高全部降低,而晋豆仅茎重和株高降低;晋豆的色素含量（叶绿素a,b,类胡萝卜素和类黄酮）不受UV－B辐射影响,在UV－B辐射下黑豆的净光合作用,气孔导度,胞间CO2浓度和蒸腾作用以及不分利用效率明显下降,而晋豆只有气孔导度和蒸腾作用减少,这可能与晋豆本身含有较高的类黄酮及较多的表皮毛和遗传特性有关,用叶片稳定碳同位素组成（δ^13C值）的分析也证明晋豆对UV－B辐射不敏感,由此看来,大豆品种对UV－B辐射的反应差异可以通过δ^13C值来判定。     

高寒退化草地不同海拔狼毒种群花大小与叶大小、叶数量的关系

植物花大小与叶大小、叶数量的关系反映了植物长期与环境相互作用形成的外在形态方面的适应对策,不同生境中其生长关系的变异体现了植物对异质环境的适应方式。本文研究了祁连山北坡高寒退化草地4个不同海拔狼毒(Stellera chamaejasme)种群花大小与叶大小、叶数量的关系。结果表明:随着海拔的升高,草地群落的高度、密度和地上生物量均呈先升高后降低的倒U型分布;狼毒的地上生物量、株高和叶大小均呈减小趋势,而繁殖分配、花大小和叶数量均呈增大的变化趋势;在海拔梯度上,狼毒花大小与叶数量呈极显著正相关(P0.01),与叶大小呈不显著负相关(P0.05),说明狼毒种群花大小与叶数量具有显著的依赖关系;生境对狼毒花大小与叶数量之间的依赖关系产生显著影响,高海拔的环境胁迫导致狼毒个体减小,植株通过增加花大小和叶数量、减小叶大小的资源分配策略来保证物种的繁衍。     

种群密度对大果虫实形态特征与异速生长的影响

为揭示种群密度与植物形态特征、器官生物量间的异速生长关系,阐明植物在退化土地恢复过程中的适应策略,以大果虫实为材料,通过异速生长分析方法,研究种群密度对其形态特征、生物量分配与异速生长的影响。结果表明,种群密度对大果虫实的株型构建产生了显著地影响。随着密度增大,大果虫实株高呈减小趋势,其分枝数及分枝长度明显减小。大果虫实各器官生物量随密度增大而显著减小。随密度增大,茎和繁殖器官生物量分配呈减小趋势,根和叶片生物量分配呈增大趋势。这与最优化分配理论中水分、营养物质及光资源受限时的情况一致。密度对大果虫实株高:根生物量间异速生长具有显著影响,且对株高与器官生物量间异速指数和个体大小产生了极显著影响。密度对根:地上部分、叶片:根、繁殖器官:根生物量间的影响属于表观可塑性,而对根:茎、茎:地上部分、叶:其他器官及繁殖器官:其他器官生物量间的影响属于真正可塑性,说明密度改变了大果虫实的株型发育系统,并影响各器官间的异速生长,进而权衡器官生物量分配以完成生活史。     

密度对尖头叶藜生物量分配格局及异速生长的影响

植物器官指示植物不同的功能,而植物器官生物量分配比例的变化表征了植物对资源获取能力的调整。在植物生长发育过程中,植物各器官呈一种明显的异速生长规律。利用异速生长分析方法,通过模拟不同密度(16、44.4、100、400株/m~2)下尖头叶藜(Chenopodium acuminatum)的生长特性,研究密度对尖头叶藜器官生物量分配格局及异速生长的影响。结果表明,随密度增加,尖头叶藜地上和地下器官都存在不同程度的竞争:其中,根和主茎生物量分配增加,茎和地上生物量分配减少,而叶和繁殖生物量分配不随密度变化而变化。研究发现,尖头叶藜各器官间具有显著的异速生长关系:其中叶∶主茎、根∶地上部分、根∶茎、根∶主茎、繁殖器官∶地上部分及繁殖器官∶根生物量间的异速生长不随密度变化而变化,属于表观可塑性;而叶∶地上部分、叶∶根、叶∶茎、茎∶地上部分、主茎∶地上部分、繁殖器官∶茎、繁殖器官∶主茎生物量间具有极显著的异速生长关系,异速指数和个体大小显著受密度变化影响,属于真正可塑性,这表明密度能够影响尖头叶藜各器官的生长变化。尖头叶藜叶∶主茎、叶∶根及主茎∶地上部分生物量间的异速指数在D4-密度时与3/4差异不显著(P0.05),符合生态代谢理论,而在D1—D3密度时与3/4差异显著(P0.05),表明充分竞争的植株更符合代谢理论,而竞争不激烈的植株对资源的投入具有物种特异性。     

大气CO2和O3浓度升高对银杏构件生长的影响

采用开顶箱模拟试验,探讨了大气CO2和O3浓度升高对银杏构件生长的影响。结果表明：高浓度O3抑制银杏主枝和侧枝生长（P〈0．01）;高浓度CO2对银杏粗生长影响不显著（P〉0．05）,但在高浓度O3和CO2、O3复合气体条件,银杏粗生长受到严重抑制（P〈0．01）;高浓度CO2可促进银杏叶片面积和干物质的增加,并能提高叶片含水量和抗干旱能力,但在高浓度CO2、O3复合气体条件下,叶片面积增加不显著（P〉0．05）,而干物质增加极显著（P〈0．01）;O3对银杏叶片构件生长有明显抑制作用,叶面积大小和干物质量明显低于对照株（P〈0．05）。     

梭梭和多枝柽柳的末端小枝异速生长特征研究北大核心CSCD

荒漠植被柽柳和梭梭的叶退化,以绿色的同化枝来进行光合作用,目前对于荒漠植物的小枝和其支撑的非形态学意义上的叶(即绿色同化枝)之间的关系的研究非常缺乏,本文以柽柳和梭梭的末端小枝为对象,给出了小枝尺度上的生物量和同化枝面积估算方程,并对小枝的茎、同化枝生物量分配格局以及小枝大小和同化枝面积大小之间的关系进行研究,旨在探讨2种植物适应荒漠生境的小枝-同化枝大小关系的差异。结果显示:以茎径为自变量,利用幂函数构建的枝生物量和同化枝面积估算方程具有较高的相关性,柽柳方程的幂指数要比梭梭大,表明随着茎径增大,柽柳同化枝面积和枝重的增长幅度大于梭梭。柽柳枝重与茎重、同化枝重以及茎重和同化枝重之间均呈现极显著的等速生长的关系,小枝大小对同化枝、茎的生物量分配没有影响;而梭梭枝重与同化枝重、茎重以及茎重和同化枝重间均存在极显著的异速生长关系,随着小枝增大,茎在生物量分配中更占优势,这表明梭梭对于起到支撑和水分传输作用的茎的需求更大。柽柳的同化枝面积与茎截面积、茎重分别呈现大于1和小于1的极显著的异速生长关系,表明分别以茎截面积和茎重代表小枝大小,小枝支撑的同化枝面积比例随小枝增大有两种不同的变化趋势;而梭梭同化枝面积和茎截面积、茎重间均存在小于1的极显著的异速生长关系,表明小枝越大,小枝支撑的同化枝面积的比例越小。这些结果有助于在小枝尺度上了解柽柳和梭梭这两种植被适应干旱、高温的荒漠环境的功能结构特征。     

重金属镉（Cd）和增强UV—B辐射复合对大豆生长和生理代谢的影响

研究了大豆的生长、生物量、抗氧化酶活性和吲哚乙酸（IAA）氧化酶活性在Cd^2 、UV－B辐射和二者复合胁迫（Cd UV-B)下的变化。结果表明,Cd^2 和UV－B辐射都抑制大豆生长,并显著抑制根的伸长,二者复合后加强了对根伸长的抑制。UV－B辐射显著增强了POD、SOD活性,Cd^2 对POD活性影响不明显,但却拮抗UV－B对POD活性的诱导,SOD活性在各种胁迫下显著增强。虽然Cd%2 对叶片类黄酮含量影响不明显,但对UV－B诱导的类黄酮合成有一定影响。IAA氧化酶活性在复合作用下下降,可能是复合胁迫影响大豆生长的重要因素之一。     

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、...     

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     

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.     

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。     

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.     

Effect of soil salinity and water stresses on growth and content of nitrogen,chloride and phosphate of wheat and triticale

Summary Three wheats and one triticale were grown, up to flowering stage, in pots on calcareous soil adjusted to a range of salinities (S₁=3.5, S₂=6, S₃=8.5, and S₄=11 mmhos/cm, 20°C, soilpaste extract) by adding solution consisting of 3∶2∶1 of Na-, Ca- and Mg chlorides in chemical equivalent amounts. Moisture in the pots was kept at 100% (W₁), 40% (W₂) and 20% (W₃) of the available water. The vegetative growth, nitrogen and phosphate were affected by S and W treatments, chloride was affected only by S. The interaction S×W affected only dry weight. Varietal effect was observed between wheat as a group and triticale. Multiple quadratic regression equations of these properties on salinity and water revealed that the higher the available water the wider the range of tolerable salinity. Triticale was relatively more tolerant to water stress. Salinity increases Cl and decreases N, whereas water stress enhances N accumulation to a certain extent. However, in triticale at S₃ and S₄ the effect of water stress on N was overshadowed by the excessive salinity. This did not occur for the wheat (Florence). P trends were described. R² for P was low (0.7435–0.3603) which made interpretations rather difficult.