卫矛科植物苦皮藤杀虫成分化学研究新进展

卫矛科植物苦皮藤(Celastrus angulatus Max.)是我国著名的杀虫植物。近些年来,我国对这一杀虫植物从化学和生物学的角度进行了多学科的交叉研究。本文结合笔者近年来的研究,从苦皮藤的杀虫化学成分的结构、构效关系、环境中的稳定性以及结构修饰等方面综述了对苦皮藤杀虫成分化学研究的新进展。     

13种卫矛科植物杀虫活性研究

研究了13种卫矛科植物根皮的39种提取物对3龄粘虫幼虫(Mythimna sepamte Walker)的杀虫活性。胃毒处理表明6种植物有麻醉活性,7种植物有毒杀活性,触杀处理表明仅2种植物的3种提取物有触杀活性。对玉米象(Sitophiuls zeamais Motschulsky)的种群抑制处理表明,13种植物的36种提取物对玉米象种群有一定程度的抑制作用,但总体上低于文献报道的苦皮藤乙醚提取物的活性。     

福建杀虫植物资源初步调查

福建杀虫植物有53科107种。含种类较多的科有:菊科8种;豆科、大戟科各7种;卫矛科、蓼科、唇形科、茄科各4种。通过综合分析认为,福建杀虫植物中以苦楝、苦皮藤、鱼藤、苦参、羊踯躅、羊角拗、苦蓝盘、猪毛蒿、烟草、辣蓼、土荆芥、百部等具有较高的开发价值。本文对福建杀虫植物的研究方向和合理开发利用提出若干建议。     

苦皮藤种油对几种蔬菜和贮粮害虫拒食的研究

室内测定表明:苦皮藤种油对菜青虫、黄守瓜、猿叶虫、28星瓢虫等4种蔬菜害虫有明显的拒食作用,对赤拟谷盗、谷蠹具有较明显忌避作用,对玉米象有明显的拒食作用、干扰产卵及抑制卵的孵化作用,对四纹豆象有较高的防治效果。田间试验效果:防治青菜虫用2%、0.66%、0.5%的苦皮藤种油,防效分别为86.5%、91.16%、85.37%,10%氯氰菊酯5000倍液为89.6%,苦皮藤根皮粉为79.81%。所以,苦皮藤种油与菊酯类农药的效果相似。     

苦皮藤主要杀虫有效成分的杀虫作用机理及其应用

卫矛科植物苦皮藤Celastrus angulatus Max.是我国著名的杀虫植物,自1980年代以来,已从化学和生物学的角度对这一杀虫植物进行了多学科的交叉研究。该文综述了苦皮藤中化合物的主要生物活性,包括对昆虫的拒食作用、毒杀作用、麻醉作用,对植物病菌的杀菌作用以及抗癌活性。就主要杀虫成分的杀虫作用机理,特别是对苦皮藤素Ⅳ可能作用于昆虫神经肌肉突触、苦皮藤素Ⅴ作用于昆虫消化系统以及在中肠肠壁细胞膜上可能存在有苦皮藤素Ⅴ受体的研究进行了总结。此外,还综述了苦皮藤素制剂的应用技术和环境毒理学的有关研究。最后,分析和讨论了这些研究中存在的问题及其发展前景。     

猪常用植物性饲料氨基酸消化率

采用8头初始体重平均为27.2kg±2.3kg、在回肠末端装有简单T型瘘管的杜长大三元杂交公猪,手术康复后随机分成2组,每组4头,每组采用同一豆粕-玉米淀粉基础日粮,按拉丁方设计,用于测定豆粕、棉粕、菜粕、稻谷、油糠、统糠和玉米7种饲料原料的回肠和粪氨基酸消化率。结果表明,所测氨基酸平均表观消化率回肠比粪低5%~8%(P<0.05);稻谷氨基酸表观消化率比玉米低5%;所测原料氨基酸表观消化率与中国饲料数据库和前人报道结果基本吻合。     

野生植物苦皮藤种油对几种主要害虫防治研究报告

室内测定表明:苦皮藤种油对菜青虫、黄守瓜、猿叶虫、28星瓢虫,丝绵木金星■蠖、缀叶丛螟等六种害虫有明显的拒食作用;田间试验效果:防治菜青虫,用2%、0.66%、0.5%的苦皮藤种油防效分别为86.5%、91.16%、85.37%,10%氯氰菊酯5000倍液为89.6%,苦皮藤根皮粉为79.81%,所以,苦皮藤种油与氯氰菊酯的效果相近,但优于苦皮藤根皮粉;防治黄守瓜,其防效与增产均优于DDVp。苦皮藤资源丰富,其种油将有可能成为一种很有发展前途的植物性天然产物杀虫剂或拒食剂。     

长期轮作对黄土高原旱地小麦籽粒蛋白质营养品质的影响

在长期定位试验条件下,研究了黄土高原旱地粮草（小麦-红豆草）、粮豆（小麦-豌豆）和粮饲（小麦-玉米）3种典型轮作制度对小麦籽粒蛋白质营养品质的影响.结果表明： 轮作制度及茬口年限可对黄土高原旱地小麦籽粒蛋白质营养品质产生不同程度的影响.与连作小麦相比,实行小麦-红豆草轮作后,小麦籽粒蛋白质营养品质较稳定,且其籽粒蛋白质必需氨基酸含量、氨基酸评分、氨基酸比值系数、化学评分和氨基酸指数均较高,可作为黄土高原生产优质蛋白小麦的轮作制度;小麦与豌豆进行轮作,豌豆茬后1年小麦籽粒蛋白质营养品质较高,但豌豆茬后2年小麦籽粒蛋白质必需氨基酸含量较低,且多种必需氨基酸评分和化学评分低于连作小麦,必需氨基酸指数比连作小麦低12.2%,营养品质较低;虽然粮饲轮作小麦籽粒蛋白质营养品质较稳定,但其粗蛋白、必需氨基酸含量及氨基酸平衡程度均低于连作小麦.     

长期轮作对黄土高原旱地小麦籽粒蛋白质营养品质的影响

在长期定位试验条件下,研究了黄土高原旱地粮草(小麦-红豆草)、粮豆(小麦-豌豆)和粮饲(小麦-玉米)3种典型轮作制度对小麦籽粒蛋白质营养品质的影响.结果表明:轮作制度及茬口年限可对黄土高原旱地小麦籽粒蛋白质营养品质产生不同程度的影响.与连作小麦相比,实行小麦-红豆草轮作后,小麦籽粒蛋白质营养品质较稳定,且其籽粒蛋白质必需氨基酸含量、氨基酸评分、氨基酸比值系数、化学评分和氨基酸指数均较高,可作为黄土高原生产优质蛋白小麦的轮作制度;小麦与豌豆进行轮作,豌豆茬后1年小麦籽粒蛋白质营养品质较高,但豌豆茬后2年小麦籽粒蛋白质必需氨基酸含量较低,且多种必需氨基酸评分和化学评分低于连作小麦,必需氨基酸指数比连作小麦低12.2％,营养品质较低;虽然粮饲轮作小麦籽粒蛋白质营养品质较稳定,但其粗蛋白、必需氨基酸含量及氨基酸平衡程度均低于连作小麦.     

阿拉善荒漠4种植物叶RNA/DNA比和RNA/蛋白质比的季节变化

为比较进展演替和正在演替中建群植物体内RNA/DNA比、RNA/蛋白质比的变化,选择阿拉善荒漠基于流沙基质演替系列建群植物籽蒿(Artemisia sphaerocephalla)、油蒿(A. ordosica)、冷蒿(A. frigida)与猫头刺(Oxytropis aciphylla)为对象,分析了生长季4种植物幼嫩枝叶RNA、DNA、蛋白质以及RNA/DNA比和RNA/蛋白质比的季节变化。结果表明,叶DNA含量,4种植物均为5月最低,籽蒿和猫头刺7月最高而油蒿和冷蒿5至9月逐渐升高;叶RNA含量,油蒿和冷蒿7月最高,籽蒿5月最高、7月最低,猫头刺5至9月逐渐升高;叶蛋白质含量,4种植物均为7月最低、9月最高;叶RNA/DNA比,籽蒿和猫头刺7月最低而油蒿和冷蒿7月最高,随进展演替4种植物叶RNA/DNA比生长季均值逐渐降低;叶RNA/蛋白质比,4种植物均为7月最高且显著高于5月,演替替代种冷蒿叶RNA/蛋白质比生长季均值高于被替代种油蒿。可见,演替系列建群植物与演替群落被替代种和替代种叶RNA/DNA比与RNA/蛋白质比存在明显季节分异并与植物生长快慢相关。     

Conformational isomers of insect odorant-binding proteins.

We have identified and cloned the cDNAs encoding odorant-binding proteins (OBPs) from the large black chafer, Holotrichia parallela, and the yellowish elongate chafer, Heptophylla picea. Each species possess two OBPs, the proteins migrating faster in native gels (OBP1) showed high amino acid identity (>88%) to previously identified pheromone-binding proteins (PBPs) from scarab beetles. HparOBP1 and HpicOBP1 have 116 amino acids and six highly conserved cysteine residues. In contrast to OBP1 that gave a single band, both HparOBP2 and HpicOBP2 separated each into two bands in native gels (15%). The N-terminal amino acid sequences for the two bands from each species were indistinguishable, and they had the same molecular masses. Although we sequenced several clones from each species, they all encode only one protein for each species, indicating they are different conformational isomers of the same protein. HparOBP2 and HpicOBP2 have 133 amino acids and cysteine residues are conserved in proteins of the same family.     

Genetic variability and improvement of seed proteins in wheat

Summary Albumins, globulins, gliadins and glutenins presumably comprising 100 percent of the wheat seed proteins were sequentially extracted and electrophoresed on SDS-polyacrylamide gels. The SDS-electrophoretic patterns within each of the four fractions from T. boeotiaum, T. urartu, T. turgidum, T. timopheevii, T. aestivum, Ae. speltoides and Ae. squawosa were similar. They differed from one species to another only in a few minor components or density of certain components. Similarity in MW's of components, as indicated by the SDS-electrophoretic patterns, suggests that the wheats and Aegilops exhibit no variability for structural genes coding seed proteins. A minimum of 60 to 70 and a maximum of 360 to 420 structural genes with major or minor effects control the total seed protein in T. aestivum. Presumably, only one or the other homoeoallele was expressed in the polyploids. Different components of albumins and globulins presumably had distinct MW's and amino acid composition, while the components of gliadins and glutenins could be classified into a few groups each containing one or more components with the same MW and nearly identical amino acid composition. The genes for components with similar MW's and amino acid composition arose through multiplication of a single original gene and perhaps share the same regulatory mechanism. Seed protein content and quality in wheat might be improved through the incorporation of structural genes, coding for polypeptides with distinct MW's, from distantly related species, rather than by manipulation of the structural genes within the Triticum-Aegilops group. Regulatory mutants similar to opaque-2 of corn could be used to alter the proportion of gliadins in relation to albumins and globulins, to improve amino acid composition of wheat proteins.     

Analysis of the amino acid sequence of homologous proteins on the personal computer "Iskra-226"

The presented software package allows: 1) to input and edit amino acid sequences; 2) to list aligned amino acid sequences of homologous proteins; 3) pairwise comparison of homologous sequences; 4) construction of phylogenetic trees; 5) comparison of two groups of protein sequences from the same family of homologous proteins; 6) graphic identification of conservative and variable regions of homologous sequences. The stepwise application of the programs allows to study the process of amino acid replacement accumulation during certain intervals of species evolution.     

割手密醛脱氢酶ScALDH基因的克隆与表达分析

该研究从甘蔗细茎野生种(割手密Saccharum spontaneum)中克隆抗旱相关的基因Sc ALDH,并分析其在干旱处理条件下的表达情况和序列特征。利用RT-PCR技术克隆甘蔗的ALDH基因片段,并对其核苷酸和氨基酸序列进行分析。使用NCBI Blastx、ORF finder、Mega、NCBI Conserved Domain Search等程序对其分别进行不同物种氨基酸比较、开放阅读框(ORF)寻找、进化树及保守序列分析,并用Real Time-PCR分析所克隆基因在干旱胁迫前后的表达差异。结果表明:克隆出甘蔗的ALDH基因片段,总长度为1996bp,其中蛋白质编码区(CDS)全长1524bp,编码508个氨基酸;与其它物种ALDH类蛋白氨基酸序列有很高的同源性,有ALDH家族的保守序列,并含有完整的开放阅读框,系统进化树分析显示与玉米的蛋白质亲缘关系最近;Real timePCR数据表明,在干旱胁迫下,随着干旱时间的延长,该基因的表达量呈持续积累的表达模式。总体上来说,该基因对干旱胁迫显著表达。利用RT-PCR技术克隆的甘蔗ALDH基因,属于ALDH蛋白家族的一员,具有其典型的功能域,该基因在干旱胁迫过程中参与抗旱作用。该研究结果为野生种资源开发、优良抗旱亲本选择和培育抗旱性强甘蔗品种提供了参考依据。     

New Glycoprotein-Associated Amino Acid Transporters

The L-type amino acid transporter LAT1 has recently been identified as being a disulfide-linked ``light chain' of the ubiquitously expressed glycoprotein 4F2hc/CD98. Several LAT1-related transporters have been identified, which share the same putative 12-transmembrane segment topology and also associate with the single transmembrane domain 4F2hc protein. They display differing amino acid substrate specificities, transport kinetics and localizations such as, for instance, y⁺LAT1 which is localized at the basolateral membrane of transporting epithelia, and the defect of which causes lysinuric protein intolerance. The b^0,+AT transporter which associates with the 4F2hc-related rBAT protein to form the luminal high-affinity diamino acid transporter defective in cystinuria, belongs to the same family of glycoprotein-associated amino acid transporters (gpaATs). These glycoprotein-associated transporters function as amino acid exchangers. They extend the specificity range of vectorial amino acid transport when located in the same membrane as carriers that unidirectionally transport one of the exchanged substrates. gpaATs belong to a phylogenetic cluster within the amino acid/polyamine/choline (APC) superfamily of transporters. This cluster, which we designate the LAT family (named after its first vertebrate member), includes some members from nematodes, yeast and bacteria. The latter of these proteins presumably lack association with a second subunit. In this review, we focus on the animal members of the LAT cluster that form, together with some of the nematode members, the family of glycoprotein-associated amino acid transporters (gpaAT family). Received: 20 July 1999/Revised: 7 September 1999     

A new family of plant antifungal proteins.

Plant seeds contain high concentrations of many antimicrobial proteins. These include chitinases, beta-1,3-glucanases, proteinase inhibitors, and ribosome-inactivating proteins. We recently reported the presence in corn seeds of zeamatin, a protein that has potent activity against a variety of fungi but has none of the above activities. Zeamatin is a 22-kDa protein that acts by causing membrane permeabilization Using a novel bioautography technique, we found similar antifungal proteins in the seeds of 6 of 12 plants examined. A polyclonal antiserum was raised against zeamatin and was used in immunoblots to confirm the presence of zeamatinlike proteins in these seeds. N-terminal amino acid sequencing was carried out on the antifungal proteins from corn, oats, sorghum, and wheat, and these sequences revealed considerable homology with each other. Interestingly, these N-terminal sequences are also similar to those of thaumatin, a pathogenesis-related protein from tobacco, and two salt stress-induced proteins. These results indicate that zeamatin is not unique but is a member of a previously unrecognized family of plant defense proteins that may include some species of pathogenesis-related proteins.     

Primary structure of human thromboxane synthase determined from the cDNA sequence.

Polymerase chain reaction techniques have been used to isolate a cDNA clone containing the entire protein coding region of thromboxane A2 synthase (EC 5.3.99.5) from a human lung cDNA library. The cDNA clone hybridizes with a single 2.1-kilobase mRNA species in phorbol ester-induced human erythroleukemia and monocytic leukemia cell lines. A second cDNA, differing only by an insert of 163 base pairs near the 3'-end of the translated region, was also found to be present in the same library. The proteins predicted from both nucleic acid sequences include the three polypeptide sequences determined from amino acid sequencing of the purified human platelet enzyme, five potential sites for N-glycosylation, and a hydrophobic region that may serve to anchor the synthase in the endoplasmic reticulum membrane. The longer predicted protein, designated thromboxane synthase-I, contains 534 amino acids, with a Mr of 60,684, whereas the shorter protein, designated thromboxane synthase-II, contains 460 amino acids and has a Mr of 52,408. Although thromboxane synthase-II lacks the conserved cysteine that serves as the proximal heme ligand in the other cytochromes, significant sequence similarities exist among thromboxane synthase-I and -II and several P450s, particularly those in family 3. The overall amino acid identity is considerably less than 40%, making it likely that thromboxane synthase represents a previously undefined family of cytochrome P450.     

High Plains wheat mosaic virus: An enigmatic disease of wheat and corn causing the High Plains disease

Brief historyIn 1993, severe mosaic and necrosis symptoms were observed on corn (maize) and wheat from several Great Plains states of the USA. Based on the geographical location of infections, the disease was named High Plains disease and the causal agent was tentatively named High Plains virus. Subsequently, researchers renamed this virus as maize red stripe virus and wheat mosaic virus to represent the host and symptom phenotype of the virus. After sequencing the genome of the pathogen, the causal agent of High Plains disease was officially named as High Plains wheat mosaic virus. Hence, High Plains virus, maize red stripe virus, wheat mosaic virus, and High Plains wheat mosaic virus (HPWMoV) are synonyms for the causal agent of High Plains disease.TaxonomyHigh Plains wheat mosaic virus is one of the 21 definitive species in the genus Emaravirus in the family Fimoviridae.VirionThe genomic RNAs are encapsidated in thread‐like nucleocapsids in double‐membrane 80–200 nm spherical or ovoid virions.Genome characterizationThe HPWMoV genome consists of eight single‐stranded negative‐sense RNA segments encoding a single open reading frame (ORF) in each genomic RNA segment. RNA 1 is 6,981‐nucleotide (nt) long, coding for a 2,272 amino acid protein of RNA‐dependent RNA polymerase. RNA 2 is 2,211‐nt long and codes for a 667 amino acid glycoprotein precursor. RNA 3 has two variants of 1,439‐ and 1,441‐nt length that code for 286 and 289 amino acid nucleocapsid proteins, respectively. RNA 4 is 1,682‐nt long, coding for a 364 amino acid protein. RNA 5 and RNA 6 are 1,715‐ and 1,752‐nt long, respectively, and code for 478 and 492 amino acid proteins, respectively. RNA 7 and RNA 8 are 1,434‐ and 1,339‐nt long, code for 305 and 176 amino acid proteins, respectively.Biological propertiesHPWMoV can infect wheat, corn (maize), barley, rye brome, oat, rye, green foxtail, yellow foxtail, and foxtail barley. HPWMoV is transmitted by the wheat curl mite and through corn seed.Disease managementGenetic resistance against HPWMoV in wheat is not available, but most commercial corn hybrids are resistant while sweet corn varieties remain susceptible. Even though corn hybrids are resistant to virus, it still serves as a green bridge host that enables mites to carry the virus from corn to new crop wheat in the autumn. The main management strategy for High Plains disease in wheat relies on the management of green bridge hosts. Cultural practices such as avoiding early planting can be used to avoid mite buildup and virus infections.     

Molecular cloning,sequence and expression analysis of <Emphasis Type="Italic">ZmArf2</Emphasis>, a maize ADP-ribosylation factor

A full-length cDNA encoding a maize GTP-binding protein of the ADP-ribosylation factor family was cloned by suppression subtractive hybridization and an in silico cloning approach. The cDNA was 938 bp in length and contained a complete ORF of 612 bp, which encodes a protein of 203 amino acid residues. Its deduced amino acids sequence had an 83% identity with that of a GTP-binding protein in rice. The gene was designated ZmArf2. The ZmArf2 gene consists of G1, G2, G3, G4 and G5 boxes, and Switch I and Switch II regions. Eight nucleotides differed and five amino acids changed between the popcorn inbred N04 and the dent corn inbred Dan232. One changed amino acid was in the G1 box. RT-PCR analysis showed that ZmArf2 expression increased in the early stages of endosperm development and was not tissue-specific.     

Alignment of protein sequences using the hydrophobic core scores

Making an alignment of the amino acid sequences is an essential step in the prediction of an unknown protein structure by model building from the known structure of a protein of the same family. To improve the accuracy of the alignments, we introduced the concept of hydrophobic core scores, which restrains putting insertions/deletions in the hydrophobic core regions of the protein. Eight pairs of protein sequences were aligned by this method, and the quality of the alignments were assessed by reference to those obtained by the structural superposition. The introduction of the hydrophobic core scores derived from the knowledge of the tertiary structure of one of each pair resulted in an improvement of the accuracy of the alignments. The quality of the alignment was found to depend on the homology of the protein sequences.