牛小脑肌醇磷脂激酶PI(4)K高产率纯化与特征

对牛小脑膜区肌醇磷脂激酶进行了11 500倍纯化,过程包括：TritonX-100抽提,硫酸铵沉淀,阳离子交换层析(phosphocellulose),亲和层析(Heparin Sepharose CL-6B)和阴离子交换层析(DEAE10,FPLC)等.纯化程度可达95％以上,对SDS-PAGE电泳结果进行扫描分析测其分子质量为56 ku.纯化的肌醇磷脂激酶的特异活性为450 nmol/mg·min, 动力学性质表现为ATP的表观K_m值为7.9×10^-7 mol/L,PI的表观K_m值为6.6×10^-7 mol/L. 腺嘌呤核苷是该酶的有效抑制剂,3.5×10^-7 mol/L腺嘌呤核苷可使该酶活力降低约50％,而TritonX-100对该酶活力具有刺激作用,0.5% TritonX-100可使该酶表现为最高活力.     

厚叶景天组织传感器的研究

利用厚叶景天的叶和茎组织作为生物催化材料,分别同二氧化碳气敏电极和氨气敏电极组合,研制了L－精氨酸传感器及,L－赖氨酸传感器。两种传感器的线性范围分别为1.0×10^-4 1.O×10^-3mol/L和8．0×10^-5—3.0×10^-3mol/L．检测下限分别为3．2×10^-5mol／L和2.2×10^-5mol/L,响应斜率分别为42.2mV／dec和41．4mv／dec。考察了两种传感器的回收率．结果表明,L－精氨酸传感器和L－赖氨酸传感器的回收率平均值分别为98．6％和101.6％,标准偏差分别为4.6％和4.0％。     

Nafion膜固定的亚甲基蓝为介体的生物传感器

制成了以亚甲基蓝为介体的电流型过氧化氢生物传感器,通过离子交换牢固地固定在Nafion膜中的亚甲基蓝,能有效地在辣根过氧化物酶和玻碳电极之间传递电子.探讨了pH值、温度、工作电位和抗坏血酸等物质对此传感器生物电催化还原H₂O₂的影响.此生物传感器选择性好、灵敏度高,对H₂O₂线性响应范围为5.0×10^-7～2×10^-4 mol/L,响应时间少于30 s.     

腺苷敏感组织电极的研究

将一种含丰富腺苷脱氨酶的新鲜猪肝组织切片,通过“三明治夹心”法固定于氨气敏电极上,制成对腺苷具有特异响应的生物催化组织膜电极。电极测定腺苷浓度线性范围为1.4×10^-4—1.0×10^-2mol/L,检出限为5.0×10^-5mol/L。并对介质条件,pH影响,选择性以及动力学响应行为进行研究,电极寿命达一个月以上。电极用于合成样品测定,效果满意。     

2.5次微分伏安法对生物样品中丙二醛的测定

以0.1mol/L NH₄Cl溶液为介质, 用2.5次微分伏安法测定了丙二醛, 线性范围为1.0×10^-6至1.0×10^-3 mol/L, 检测限达1.0×10^-7 mol/L. 并测定了细胞培养液介质中新生SD大鼠心室肌细胞样品中的丙二醛.     

二茂铁－交联剂修饰的葡萄糖传感器

用牛血清白蛋白-戊二醛交联剂把葡萄糖氧化酶固定在Nafion-二茂铁修饰电极上,最后在电极上修饰一层Nafion膜,制备成葡萄搪传感器,电活性物质如抗坏血酸、尿酸等对葡萄糖的测定无干扰.该传感器的线性范围为5.0×10^-4-1.3×10^-2mol/L,响应时间小于60s.     

栓菌漆酶在毕赤酵母中高效表达及重组酶的性质

栓菌420（Trametes sp. 420）漆酶基因lacD以两种方式在巴斯德毕赤酵母（Pichia pastoris）进行异源表达,产生两种重组漆酶：rLacDx（具有天然N-末端）和rLacDe（N-末端带有8个额外的氨基酸残基）。摇瓶发酵18d,rLacDx和rLacDe的产量分别为1.21×10⁵u/L、7.38×10⁴u/L ［以2,2′-连氮-3-乙苯-二噻唑-6磺酸（ABTS）为底物］。在高密度发酵条件下,rLacDx的产量增加到2.39×10⁵u/L,同时其生产周期降至7.5 d。两种重组酶对愈创木酚底物的氧化特性相似,且在50℃和pH3～10的范围内均稳定。然而,rLacDx对底物ABTS的比活力（1761u/mg）高于rLacDe （1122u/mg）,其表观K_m值(427μmol/L)低于rLacDe (604μmol/L)。     

甘油三酯酶传感器的研制及应用

将脂肪酶固定在pH玻璃电极上,制成甘油三酯酶传感器.对传感器的制作方法和响应性能进行了研究.在37℃,选择Tris-HCl缓冲溶液(pH 8.5)为测量介质, 所制传感器对甘油三酯的响应线性范围为3.09×10^－6～1.91×10^－3 mol/L,响应斜率为32.7 mV/pC, 响应时间为5～10 min, 使用寿命可达25 d.用研制的传感器测定了人和兔血清中的甘油三酯含量,结果满意.     

人脑神经元特异性烯醇化酶的纯化方法

采用改良的Grace层析方法,经一次DEAE-Sephadex A50柱层析即从人脑中纯化了神经元特异性烯醇化酶,比活力为92.1U/mg,纯化倍数为59.4.该酶纯化后,经SDS-聚丙烯酰胺凝胶电泳鉴定为单一蛋白质谱带.此外,还测定了其部分理化性质,其亚单位分子量为45000,等电点pI为4.7,氨基酸组成分析表明其为一种酸性蛋白质;对2-磷酸甘油酸的K_m值为5.6×10^-4mol/L.     

用Blue Sepharose CL-6B快速纯化天花粉蛋白

差光谱显示染料cibacron blue F3GA与天花粉蛋白(TCS)有特异性结合,复合物在可见光部分的最大吸收波长在690 nm,摩尔消光系数ε=2.6×10^-3(mol/L)^-1·cm^-1,解离常数K_d=1.8 μmol/L,0.5 mol/L NaCl可使复合物解离.根据这一特点,用Blue-Sepharose CL-6B凝胶从栝篓块茎中亲和纯化了TCS.此法快速、简便、高效,易于大量制备.     

Taxonomical studies on ovariicolous ustomycetes on caryophyllaceae I.Ustilago jehudana andUstilago moenchiae-manticae

A study of the type specimen ofUstilago jehudana resulted in the correction of the diagnosis. The sori are localized in the host gynoecium but not in the anthers. Morphological characters of the sori and ustospores of the later describedU. moenchiae-manticae are identical with these ofU. jehudana. Ustilago moenchiae-manticae is reduced here to a synonym ofU. jehudana. The smut is reported as new to Bulgaria on a new host, viz.,Moenchia erecta. A new combination,Bauhinus jehudanus, is proposed.     

降水对鄂尔多斯高原克隆植物分布的影响

鄂尔多斯高原地处半干旱区到干旱区的过渡带。通过沿鄂尔多斯高原从东到西的天然降水梯度的样带调查,分析了克隆植物的分布特征与降水的关系。结果表明:克隆植物的物种数量、占物种总数的比例和重要值以及根状茎型克隆植物的物种数量均与降水量呈显著正相关。5种优势植物克氏针茅、本氏针茅、黑沙蒿、赖草和短花针茅均为克隆植物,它们的分布也受降水影响。克氏针茅的密度、本氏针茅的盖度和密度、黑沙蒿的高度、盖度和密度以及赖草的高度均与降水量呈显著正相关。然而,赖草的盖度以及短花针茅的高度、盖度和密度均与降水量成负相关。因此,克隆植物在鄂尔多斯高原植被中具有重要作用,而且其作用随着降水量的增加而加强。     

Research on streptococci in the UK

Pleurotus florida produced high amounts of laccase (4.60 U/ml) in malt extract broth after 12 days' growth under stationary conditions. The production of laccase was semi-constitutive. Hyperlaccase mutants ofP. florida were obtained through mutagenesis of mycelial protoplasts usingN-methyl-N-nitro-N-nitrosoguanidine (50 g/ml) for 2 min. Three hyperlaccase mutants were selected showing growth and enzyme production responses similar to the parent.     

The effect of competition and edaphic conditions on the establishment of halophytes on brine effected soils

In order to test the feasibility of using native halophytes to reclaim brinecontaminated soil, seedlings of five inland halophytes, Atriplexprostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina, and Suaeda calceoliformis, were planted at threedensities on a site near Athens, Ohio which had been contaminated by oilwell brine water. Ten replicates of each density treatment weretransplanted on two distinct areas of high and low salinity in May of 1993. Seedling survivorship, soil moisture, and soil salinity were monitored weeklythroughout the growing season. Biomass production and ion uptake weredetermined for each plant surviving until harvest. Soil analyses wereperformed prior to planting and after harvest to determine overall changesin soil chemistry and to determine the amount of Na⁺ reductionfrom the soil due to leaching by precipitation during the course of theexperiment. Survival was determined to be density independent for all ofthe species with the exception of S. marina where survival wasfacilitated at high density. Increased salinity negatively affected the survivaland yield of A. prostrata. The remaining species had greater survivalunder high salinity conditions, and density appeared to be the key factorinfluencing yield. Sodium and chloride ions were accumulated in planttissues in much greater amounts than K⁺, Ca⁺²or Mg⁺². Salicornia europaea plants grown in high densityon the high salinity site accumulated the highest amount of Na⁺ andH. jubatum grown in low density on the high salinity site accumulatedthe lowest amount of Na⁺. Soil salinities measured directly from theroot zone were significantly reduced (p<0.05) at the end of thegrowing season when compared to their controls. Atriplex prostrata(high density/low salinity) plots produced the greatest reduction in soilsalinity (15.8%) and S. marina (high density/high salinity) plots hadthe least reduction (1.2%).     

Structures of acidic O-linked polylactosaminoglycans on human skim milk mucins

O-Linked glycans were isolated from human skim milk mucins or mucin-derived high-molecular weight glycopeptides and fractionated by anion exchange chromatography into neutral and acidic alditols. Major oligosaccharides contained in the acidic fraction were purified by high performance liquid chromatography and structurally characterized by a combination of fast atom bombardment mass spectrometry, methylation analysis and 500 MHz 1H-nuclear magnetic resonance spectroscopy. The structural aspects exhibited by these major species in the acidic fraction resemble those established previously for the neutral oligosaccharides from human skim milk mucins: 1) the size of the alditols varies from tri- to decasaccharides, 2) the core structure is of the ubiquitous type 2, 3) the backbone sequences are of the poly-N-acetyllactosamine type with a particular preponderance of linearly extended GlcNAc beta(1-3)Gal (major) or GlcNAc beta(1-6)Gal units (minor).     

Enzymic glycosphingolipid synthesis on polymer supports.

Two synthetic approaches leading toN-4-carboxymethyl-2-nitrobenzyloxycarbonyl derivatives of model compounds and of glycosylsphingosines are described. The carboxymethyl group can be converted into a hydrazido derivative and the resulting products react with an active ester polymer yielding light-sensitive polymeric products that may subsequently serve as acceptors in glycosyltransferase reactions.Author for correspondence. Address until September 1990; Graduate Department of Biochemistry, Brandeis University, 415 South Street, Waltham, MA 02254, USA     

Notes on three Japanese Agaricales

Three species of Agaricales from Japan are treated here. 1) From the examination of the types and additional specimens,Lyophyllum nigrescens is conspecific withHydropus nigrita from Cuba. 2)Hydropus kansaiensis sp. nov. from Otsu appears close toTrogia mellea from Malaysia. 3)Alnicola lactariolens sp. nov. from Otsu is a distinctive species in this genus because of the purple color of its spore print.This work has been supported by a grant to one of us (H. C.) by the Japanese Society for the Promotion of Science in 1988/89.     

Foraging Ants as Scavengers on Entomopathogenic Nematode-Killed Insects

Ants were the most apparent invertebrate scavengers observed foraging on entomopathogenic nematode-killed insects (i.e., insect cadavers containing entomopathogenic nematodes and their symbiotic bacteria) in the present study. Workers of the Argentine ant,Linepithema humile(Mayr), scavenged nematode-killed insects on the surface and those buried 2 cm below the soil surface. Ant workers scavenged significantly more steinernematid-killed (60–85%) than heterorhabditid-killed (10–20%) insects. More 4-day-postinfected cadavers (hosts died within 48 h after exposure to nematodes) were scavenged than 10-day-postinfected cadavers. Ten-day-postinfected hosts contained live infective juvenile nematodes therefore ants may serve as phoretic agents. Other ant species, includingVeromessor andrei(Mayr),Pheidole vistanaForel,Formica pacificaFrancoeur, andMonomoriom ergatogynaWheeler, also scavenged nematode-killed insects. These ant species removed or destroyed about 45% of the steinernematid-killed insects. These results suggest that survival of steinernematid nematodes may be more significantly impacted by invertebrate scavengers, especially ants, than that of heterorhabditid nematodes, and placement of steinernematid-killed insects in the field for biological control may be an ineffective release strategy. Because entomopathogenic nematodes kill insects with the help of symbiotic bacteria, we tested the role of these bacterial species in deterring invertebrate scavengers by injecting bacteria (without nematodes) into insects and placing the cadavers in the field. None of the insects killed by the symbiotic bacterium,Photorhabdus luminescens(Thomas and Poinar) fromHeterorhabditis bacteriophoraPoinar, were scavanged, whereas 70% of the insects killed by the symbiotic bacterium,Xenorhabdus nematophilus(Poinar and Thomas) fromSteinernema carpocapsae(Weiser), and 90% of the insects killed byBacillus thuringiensisBerliner were scavenged by the Argentine ant. We conclude thatP. luminescensis responsible for preventing ants from foraging on heterorhabditid-killed hosts.     

Anatomical studies on ectomycorrhizas

Ectomycorrhizas of 5-month-old Pinus patula plants grown in autoclaved shola soil (forest soil) inoculated with basidiospores of Amanita muscaria, Laccaria laccata and Suillus brevipes are described. The main em phasis is on the organisation of the mantle tissue as seen in plan view and features of associated hyphae and strands. The different layers in the mantle produced by the different fungi are described and illustrated.     

Studies on ciliated protozoa in eutrophic lakes: 2. Field and laboratory studies on the effects of oxygen and other chemical gradients on ciliate distribution

An investigation into the spatial distribution of hypolimnetic ciliates in three small eutrophic lakes during the period of summer stratification was carried out. Peak ciliate densities were found to occur at the oxic/anoxic boundary, ciliate numbers declining with increasing depth within the hypolimnion. The ciliates only occurred in aerobic water where oxygen levels were less than about 0.5 mgl^–1 Laboratory experiments demonstrated that the ciliates swim upwards under anaerobic conditions but swim rapidly downwards under aerobic conditions. Further laboratory experiments showed that although the bulk of the population occured within anaerobic water, the hypolimnetic ciliates are aerobes and cannot survive indefinite anoxia. Despite the demonstrable toxicity of high levels of ammonia and sulphide, it was probably excesive distance from an available source of oxygen that excluded the ciliates from the lowest levels of the hypolimnion. Possible mechanisms which allowed these aerobic ciliates to colonise anaerobic water are considered.