增强UV-B辐射对喜树生理指标及喜树碱含量的影响（英文）

喜树(Camptotheca acuminata Decne.)隶属于蓝果树科(Nyssaceae)喜树属(Camptotheca),为抗癌药物喜树碱的主要资源,提高喜树碱的积累以满足临床需求是喜树碱开发的重要途径。该研究运用UV-B辐射对2年生喜树进行每天8h辐射处理,对1年生喜树分别设置每天2h、4h、6h和8h的辐射处理,连续处理12d后分别测定各处理喜树叶的叶绿素、MDA、游离脯氨酸(Fpro)含量和SOD活性,以及幼叶、幼枝和根中喜树碱含量,分析UV-B辐射对喜树生理指标和次生代谢物的影响,以揭示喜树碱为喜树适应UV-B辐射逆境的防御产物。结果显示:(1)2年生喜树经UV-B每天8h辐射处理12d后,叶绿素含量较对照显著降低,而MDA、Fpro和喜树碱含量均增加,说明每天8hUV-B辐射对2年生喜树产生了较强的胁迫伤害。(2)1年生喜树经UV-B辐射处理12d后,随着每天UV-B辐射时间的增加,叶绿素含量不断降低,Fpro含量显著增加;每天2~6h处理的MDA含量与对照无显著差异,但总体随处理时间增加呈上升趋势;每天8hUV-B辐射的MDA含量较对照显著增加;SOD活性随每天处理时间的延长呈先下降、后上升、再下降的变化趋势,说明每天8h的UV-B辐射对一年生喜树也产生了胁迫伤害。(3)1年生喜树幼叶、幼枝和根中喜树碱含量随着每天UV-B辐射时间的延长均呈递增趋势,而且每天8h辐射处理的喜树碱含量均最高,其中幼叶和幼枝中喜树碱含量显著高于根中含量。实验结果表明,增强UV-B辐射对喜树造成了一定的伤害,而喜树通过改变生理以及次生代谢机制,以进一步产生喜树碱来响应增强UV-B的胁迫。     

增强UV-B辐射与干旱复合处理对小麦幼苗生理特性的影响

为研究由于平流层臭氧层减薄紫外线B辐射增强在干旱地区对春小麦生理特性的影响的特殊性,模拟平流层臭氧减少20％时辐射到地表的紫外线B（UV－B,280－315nm)的增强和水分胁迫（－0.5Mpa,聚乙二醇PEG－6000处理获得）,通过测定两种胁迫下春小麦（Triticum aestivum L.)叶绿素含量、类黄酮含量、水势、细胞膜相对透性、超氧歧化酶（SOD）活性及丙二醛（MDA）含量,研究了增强UV－B辐射和水分胁迫复合作用对温室种植的小麦幼苗生理生化的影响。实验结果表明,虽然水分胁迫和UV－B辐射单独或复合处理都使春小麦的叶绿素含量降低,但仅UV－B辐射增强单独处理显著地降低小麦叶绿素a、b和总叶绿素的含量,而水分胁迫以及复合处理对叶绿素的含量的降低作用不显著。两种胁迫无论是单独作用还是复合作用均能使类黄酮含量升高,并且处理第3天比第1天高出近50％,复合处理下类黄酮的含量大于两个因子单独处理。UV－B辐射和水分胁迫处理1d对春小麦叶片的相对电导率的影响不明显,处理3d后两种胁迫下相对电导率均上升,表明膜透性增加,其中水分胁迫作用下增加尤其明显。膜质过氧化产物丙二醛的含量,在两种因子单独和复合作用下都升高,说明膜的生理功能受到了一定的不利影响。活性氧清除剂超氧化物歧化酶（SOD）的活性在各种处理下,都没有发生改变。虽然增强的UV－B辐射和干旱处理一样,会显著降低植物水势,但是,UV－B辐射与干旱同时处理时叶片水势降低的程度,不但没有比两者分别处理时降低程度之和低,而且比单做干旱处理时的降低程度还低,这表明UV－B辐射和干旱胁迫同时处理时,UV－B辐射不但没有加重水分胁迫,反而减轻了干旱对春小麦生长的胁迫。由此可以认为,在干旱条件下,增强UV－B辐射不会加剧而是有利于提高小麦对干旱的抗性。     

不同种源喜树幼枝中喜树碱的含量

通过HPLC测定了喜树(Camptotheca acuminata)不同器官及不同种源幼枝中喜树碱的含量.结果表明,喜树碱含量在叶、种子和幼枝(幼叶和幼茎)中较高,木质部中较少,髓中最低.不同种源的幼枝中,来自成都种源喜树的喜树碱含量最高.通过比较,两年生喜树各器官中喜树碱含量普遍比一年生高,幼枝中顶枝的喜树碱含量比侧枝高.     

不同种源喜树幼枝中喜树碱的含量

通过HPLC测定了喜树(Camptotheca acuminata)不同器官及不同种源幼枝中喜树碱的含量。结果表明, 喜树碱含量在叶、种子和幼枝(幼叶和幼茎)中较高, 木质部中较少, 髓中最低。不同种源的幼枝中, 来自成都种源喜树的喜树碱含量最高。通过比较, 两年生喜树各器官中喜树碱含量普遍比一年生高, 幼枝中顶枝的喜树碱含量比侧枝高。     

芒果老叶在增强UV-B辐射处理下的损伤和保护反应

以‘台衣一号’芒果盆栽苗离体老叶为试材,研究增强UV—B辐射条件下芒果老叶的损伤和保护反应。结果表明：UV—B辐射处理使芒果叶片MDA含量和相对电导率升高、叶绿素含量和叶绿素a／b降低,表明叶片受到损伤,且随处理时间延长叶片损伤加重。UV—B辐射处理叶片可溶性蛋白含量、抗氧化酶（SOD、CAT、POD）活性、保护色素（类胡萝卜素、类黄酮）和还原型GSH含量显著高于对照叶片,UV—B辐射处理叶片维生素C含量显著低于对照叶片,表明增强UV—B辐射可诱导叶片细胞通过提高活性氧清除能力和积累保护色素而直接吸收部分UV—B辐射来提高抗增强UV—B辐射损伤的能力。     

2种杨树光合色素和抗氧化系统对UV-B与NaCl胁迫的响应

以胡杨和俄罗斯杨(黑杨杂交种)为材料,通过设置增强UV-B辐射、NaCl胁迫(100mmol/L NaCl)、复合胁迫(增强UV-B辐射+100mmol/L NaCl)及对照(不额外施加NaCl和UV-B)4组处理,研究2种杨树对UV-B辐射、NaCl胁迫及其复合胁迫的生理响应及其种间差异。结果显示:(1)增强UV-B辐射、NaCl胁迫及其复合胁迫下,2种杨树的叶绿素含量降低,叶绿素a/b比值减小,类胡萝卜素含量升高;叶片中的膜脂过氧化产物(MDA)和H2O2含量均显著升高;但在复合胁迫下,俄罗斯杨MDA含量要明显低于各单一胁迫处理,而胡杨MDA含量和2种杨树H2O2含量均介于2种单一胁迫处理之间。(2)在3种不同胁迫条件下,俄罗斯杨和胡杨叶片中过氧化物酶(POD)和过氧化氢酶(CAT)活性比对照显著升高,且POD活性在复合胁迫下最高。(3)2种杨树叶片中渗透调节物质(脯氨酸、甜菜碱、可溶性蛋白)含量在各胁迫条件下均比对照明显升高,且脯氨酸和可溶性蛋白含量在复合胁迫下最高;胡杨甜菜碱含量在3种胁迫条件下的升高幅度均远大于俄罗斯杨,而俄罗斯杨可溶性蛋白含量升高的幅度在增强UV-B辐射和复合胁迫下却明显高于胡杨。研究表明,增强UV-B辐射、NaCl胁迫及其复合处理对2种杨树生长均造成不同程度的胁迫伤害,但2种杨树在复合胁迫下表现出的抗氧化保护能力比在2种单一胁迫下更强,因而复合胁迫对2种杨树的伤害更小,UV-B辐射可能与NaCl胁迫相互拮抗最终减缓了对植物的伤害。     

不同小麦品种对UV-B辐射增强响应的生理特性差异

研究了大田条件下模拟增强UV-B辐射（500 KJ·m^-2,相当于昆明地区臭氧层减少20%）对10个小麦品种生理指标的影响以及小麦对UV B辐射响应的种内差异.结果表明,10个供试小麦品种中有6个品种的叶绿素含量显著下降,叶绿素a降低的程度大于叶绿素b,从而导致叶绿素a/b的比率下降.UV-B对小麦叶片内MDA和类黄酮的影响也具有种内差异,有5个品种的MDA含量显著上升, 2个品种的MDA含量显著下降;4个品种的类黄酮含量显著增加,2个品种的类黄酮含量显著减少.叶绿素和类黄酮含量变化与MDA含量均呈显著负相关关系,类黄酮与小麦UV-B抗性之间存在密切联系.     

增强UV-B辐射对喜树幼苗生物量和两种生物碱含量的影响

通过盆栽试验,以自然辐射为对照,研究人工增强UV-B辐射下(5.0 μW/cm2)喜树幼苗生物量和各器官中喜树碱、10-羟基喜树碱含量的变化,试验结果表明:(1 )UV-B辐射处理前20d,处理组幼苗的全株以及各器官的鲜重与对照相差很少.至辐射处理的40d,处理组幼苗的全株以及各器官的生物量均高于正常条件的幼苗.试验后期,处理组单株生物量降低,长时间的UV-B辐射使喜树植株矮化、基茎加粗,同时还改变了喜树生长过程中干物质的分配,较多的干物质分配到喜树的茎和根中,而较少进入叶中;(2)UV-B辐射增强能明显增加喜树地上器官中喜树碱的含量,而对10-羟基喜树碱含量影响不明显.(3)各器官中生物碱含量与生物量的积累速率具有一定的相关性,生物量增长过快时单位质量植物体中的生物碱含量下降.     

油菜素内酯对霍山石斛抗冷性能的调控效应

以2年生霍山石斛(Dendrobium huoshanense)的当年生茎叶为试验材料,在叶面喷施0、0.01、0.05、0.10和0.50mg·L-1油菜素内酯(BR)后,进行48h昼/夜温度为(4±1)℃/(2±1)℃的低温胁迫处理,测定其幼苗叶片叶绿素含量、抗氧化酶活性、丙二醛含量和电导率及脯氨酸含量和可溶性糖含量的变化,研究BR对霍山石斛抗冷性的影响。结果显示:(1)低温胁迫条件下,霍山石斛叶片叶绿素含量随胁迫时间推移而不断降低;SOD、POD与CAT活性变化趋势均呈单峰曲线,峰值出现在低温胁迫后10d;MDA含量和电导率均持续提高。(2)叶面喷施BR预处理显著缓解了低温胁迫对霍山石斛的伤害,显著提高其叶片叶绿素含量,显著增强了SOD、POD与CAT的活性,显著降低其MDA含量和电导率;并显著提高了叶片中脯氨酸含量与茎中可溶性糖含量。(3)BR浓度为0.10mg·L-1的处理效果显著优于其它浓度处理。研究表明,在低温胁迫条件下,油菜素内酯能够通过增强霍山石斛叶片内抗氧化酶活性,提高其渗透调节能力,有效减轻低温造成的过氧化伤害,提高叶片叶绿素含量,增强其植株的抗冷性,并以0.10mg·L-1油菜素内酯效果最佳。     

喜树幼枝的喜树碱积累及其组织内定位

对喜树幼枝发育过程中各组织结构变化的观察和喜树碱含量的分析,以及荧光显微技术对喜树碱的定位研究,结果表明,幼茎和幼叶表面的单细胞腺毛和幼茎及幼叶内部由1～2层细胞包围而成的分泌道是喜树碱的主要积累部位.     

Tomato contains two differentially expressed genes encoding B-type phytochromes,neither of which can be considered an ortholog of Arabidopsis phytochrome B

Tomato (Solanum lycopersicon L.) contains two B-type phytochrome genes (PHYB1 and PHYB2). Fragments of these two PHYB were cloned following amplification by the polymerase chain reaction of a portion of their relatively well conserved 5 coding regions. Polypeptides encoded by these gene fragments exhibit 90% sequence identity. These two PHYB are independently expressed in organ-specific fashion. In mature plants, PHYB2 mRNA is most abundant in fruit and PHYB1 mRNA in expanded leaves. A phylogenetic analysis fails to establish which tomato PHYB is orthologous to either Arabidopsis PHYB or PHYD, the latter being a second B-type phytochrome. Instead, this analysis indicates that following the divergence of the Solanaceae and Brassicaceae from one another, a PHYB gene duplicated independently in each lineage. Consequently, Arabidopsis PHYB mutants cannot be considered strictly equivalent to the tomato tri mutants, which appear to be mutated at the PHYB1 locus. Similarly, other putative PHYB mutants might not be equivalent to those described for Arabidopsis and tomato. This situation complicates efforts to determine PHYB function because there might be no one answer to this question.Abbreviations PCR polymerase chain reaction - PHY undesignated phytochrome gene - PHYA, PHYB, etc phytochrome gene(s) of the A, B, etc. type This research was supported by USDA NRICGP grant 93-00939 and by NATO travel grant CRG 931183. It was initiated when two of us (L.H.P., M.-M.C.-P.) spent a sabbatical year at the Institut National de la Recherche Agronomique in Versailles, France. L.H.P. gratefully acknowledges support provided by a senior guest fellowship from the Ministère de l'enseignement superieur et de la recherche during his stay in Versailles. L.H.P. and M.-M.C.-P thank all of their colleagues in Versailles for their warm hospitality and their willingness to share their expertise with us. We also thank Russell Malmberg, Richard Meagher and Robert Price for helpful discussions concerning the interpretation of molecular phylogenies.     

Development of primary cell culture from <Emphasis Type="Italic">Scylla serrata</Emphasis>

This paper reports for the first time, the Primary cell culture of hepatopancreas from edible crab Scylla serrata using crab saline, L-15 (Leibovitz), 1 × L-15 + crab saline, 2 × L-15 + crab saline, 3 × L-15 and citrate buffer without any serum. We could isolate and maintain E (Embryonalzellen), F (Fibrenzellen), B (Blasenzellen), R (Restzellen) and G (Granular cells). Upon seeding the hepatopancreatic E, F, B, and R cells showed different survival pattern over time than granular cells. A modified L-15 (3×) medium supported the best survival of hepatopancreatic E, F B, and R cells in in-vitro culture. However granular cells could be maintained for 184 days with L-15 (1×) + crab saline. Fetal bovine serum was not effective additive and hampered cell viability in present study.     

Impaired negative cooperativity of the semisynthetic analogues human [LeuB24]- and [LeuB25]-insulins

Several semisynthetic analogues of human insulin were prepared by enzyme-assisted coupling of synthetic octapeptides to the C-terminal of porcine desoctapeptide insulin. We report the receptor-binding and biological properties of [Leu^B24]- and [Leu^B25]-insulins, one of which has the same sequence as a “mutant” insulin recently found in a diabetic patient (Tager, H. et al.(1979) Nature $\text{28}$:121–125). [Leu^B24]- and [Leu^B25]-insulins had, respectively, 8–12% and 0.9–1.1% of the binding affinity of human insulin, and 11% and 2.7% of its potency in stimulating lipogenesis in isolated rat fat cells. Neither one was an antagonist of the biological effects of native insulin. While the ability of [Leu^B24]-insulin to induce negative cooperativity was clearly impaired, that of [Leu^B25]-insulin was almost abolished. [Leu^B25]-insulin was also a potent antagonist of the negative cooperativity induced by native insulin.     

拉米夫定联合胸腺肽A1 治疗慢性乙型肝炎的疗效观察

目的:探讨拉米夫定(LAM)联合胸腺肽α1(Tα1)治疗慢性乙型肝炎的长期疗效和安全性。方法:72例慢性乙肝患者(HBV-DNA和HBeAg均阳性),按1:1随机分配进入联合治疗组(LAM+Tα1组)和单用拉米夫定组(LAM组)。结果:治疗1年时LAM+Tα1组HBeAg血清转换率(44.4%,16/36例)明显高于LAM组(5.6%,2/36例),P<0.01。停药1年后,持续的HBeAg血清转换率分别为36.1%(13/36例)和8.3%(3/36例),P<0.01。治疗过程中及停药后,两组HBV-DNA水平均明显下降,但两组的HBV-DNA转阴率相仿。治疗后1年ALT复常率联合治疗组与拉米夫定组相似,分别为75%(27/36例)和66.7%(24/36例)、随访1年时ALT复常率联合治疗组明显高于拉米夫定组,分别为58.3%(21/36例)和16.7%(6/36例)。在治疗过程中,未发现严重的不良反应。结论:LAM联合Tα1治疗慢性乙肝,不良反应少,疗效优于单一LAM用药组。     

真核表达载体pcDNA3.1-myc-his(-)B的改构与应用

目的:对真核表达载体pcDNA3.1-myc-his(-)B进行改构,以简化目的基因克隆的步骤。方法:用事先设计好的2条寡核苷酸链互相退火,替换pcDNA3.1-myc-his(-)B的多克隆位点中NotⅠ与HindⅢ间的部分;利用改构的真核表达载体,分别构建亲环蛋白A、胆绿素还原酶B和过氧化氢酶基因的重组真核表达载体,瞬时转染293T细胞后,用His标签抗体验证其表达。结果:测序结果证实已将预想的序列替换至pcDNA3.1-myc-his(-)B的多克隆位点中相应位置,改构为质粒pcDNA3.1(-)reconstruct;利用改构的真核表达载体表达了相应的目的基因。结论:改构的真核表达载体pcDNA3.1(-)reconstruct可以简化融合myc和His标签的目的基因克隆的过程,并且增加了限制性位点的可选择性。     

Macroporous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) resins—Versatile immobilization supports for biocatalysts

Crosslinked macroporous hydrophilic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate)s [abbreviated poly(GMA-co-EGDMA)] with identical chemical structure (60% of glycidyl methacrylate) but with varied average pore sizes (from 30 to 560 nm), specific surface areas (from 13.2 to 106.0 m²/g), specific volumes (from 0.755 to 1.191 cm³/g) and particle sizes (less than 100–650 μm) were synthesized via suspension polymerization. The influence of the resin properties on the loading of Candida antarctica lipase B (Cal-B) during immobilization and on the hydrolytic (hydrolysis of para-nitrophenyl acetate) and synthetic (ring-opening polymerization of -caprolactone) activity of the immobilized Cal-B were studied. Immobilization of Cal-B was performed at different temperatures and pH values. Cal-B immobilized at 30 °C and pH 6.8 was leading to increased activities. By decreasing the resin diameter: (i) the amount of Cal-B adsorbed onto the resin decreases, (ii) the conversion of para-nitrophenyl acetate increases (hydrolytic activity) and (iii) the conversion of -caprolactone and the molecular weight of the synthesized poly--caprolactone increases (synthetic activity). Varying the porosity parameters results in different hydrolytic and synthetic activities. Pore sizes of all synthesized resins (from 30 to 560 nm) are big enough to overcome diffusion limitations. Therefore increasing the pore size of the resins resulted in a large increase in the hydrolytic and synthetic activity. Increasing the specific surface area resulted in an increase of activities, as the result of alleviated substrate approach to the immobilized enzyme zones. The obtained results were compared to results from dried Cal-B powder and Novozyme 435. Resin with particle size less than 100 μm and pore size 48 nm had much higher hydrolytic activity than both dried Cal-B powder and Novozyme 435. Nearly similar trends were observed for the synthetic activity.Via the DMSO leaching technique we could show that about 80% of Cal-B was covalently attached to the macroporous resin.     

CALB脂肪酶在毕赤酵母中的组成型表达及纯化

根据南极假丝酵母脂肪酶calb的成熟多肽序列,人工合成了由毕赤酵母（Pichia  pastoris)偏爱密码子组成的calb基因序列（仅成熟肽）。将该基因克隆至穿梭质粒pGAPZαΑ中,获得的重组质粒pGAPZαA calb 经线性化后转入毕赤氏酵母GS115菌株,构建成组成型表达CALB的酵母工程菌株。酵母转化子在YPD 培养基上传代10 次后, 其外源基因未丢失。经摇瓶发酵4天后,CALB水解活力为14.5U/ml。经脱盐和阴离子交换两步纯化后,其纯度达到了95%以上,目的蛋白的含量达到了220mg/L。     

In vitro production of pectolytic and cellulolytic enzymes byColletotrichum lindemuthianum isolated from soybean grown in Saudi Arabia

Colletotrichum lindemuthianum isolated from soybean in Saudi Arabia produced polygalacturonase, pectin methylesterase, pectin trans-eliminase and carboxymethylcellulasein vitro. Polygalacturonase showed maximaum activity at 30 to 35°C and pH 4.0 to 5.0. The absorption maximum for pectin trans-eliminase reaction products was at approximately 548 nm. The polygalacturonase and pectin trans-eliminase activities increased with culture age. The degradation of carboxymethylcellulose was also demonstrated.     

Nucleotide sequence homology of the tetracycline-resistance determinant naturally maintained in Bacillus subtilis Marburg 168 chromosome and the tetracycline-resistance gene of B. subtilis plasmid pNS1981

The nucleotide sequence (1579 bp) of tetracycline-resistance determinant and flanking regions of the cloned 5.1 kb DNA fragment from Bacillus subtilis GSY908 chromosome (Sakaguchi, R. and Shishido, K. (1988) Biochim. Biophys. Acta 949, 49–57) were determined and compared with those of the B. subtilis tetracycline-resistance plasmid pNS1981. The tetracycline-resistance structural (tet) genes of the B. subtilis GSY908 chromosome (tet BS908) and pNS1981 (tet pNS1981) were found to be highly homologous (80% identical). Both tet genes were composed of 1374 bp and 458 amino-acid residues initiating from a GTG codon preceded by a ribosome-binding site (RBS-2). Upstream from tet BS908 there exists a short open reading frame (20 amino acids) initiating from a ATG codon preceded by its own RBS (RBS-1). This leader sequence was also highly homologous to that of tet pNS1981 except for a deletion of one bp between the RBS-1 and the ATG codon.     

Conjugal transfer of aminoglycoside and macrolide resistance between Enterococcus faecium isolates in the intestine of streptomycin-treated mice

The purpose was to study conjugal transfer of resistance genes between a multi-resistant Enterococcus faecium isolate and a sensitive E. faecium isolate. Co-transfer of erm(B)-Tn5405-like element and aac(6')-Ie-aph(2')-Ia was obtained in both in vivo and in vitro. Plasmid profiles and Southern blots showed that both the erm(B)-Tn5405-like element and aac(6')-Ie-aph(2')-Ia were placed on the same large plasmid (>147 kb). These data show to our knowledge the first co-transfer of the erm(B)-Tn5405-like element and aac(6')-Ie-aph(2')-Ia. The in vivo study also indicates that transfer of resistance genes between enterococci might occur under natural conditions in the gut of animals.