Diethylamide of thujic acid: a potent repellent of Aedes aegypti

A series of novel, representatively substituted amides of thujic acid were prepared and screened for insect repellent and attractant potential. In repel-lency tests the N,N-diethylamide was the most potent compound, surpassing the activity of the standard repellents dimethyl phthalate and fencholic acid. In contrast, the N-monoethylamide displayed attractant activity.     

A new arbovirus from Aedes albopictus, an Asian mosquito established in the United States

Ten strains of a new arbovirus belonging to the Bunyamwera group (Bunyaviridae) were recovered from field-collected Aedes albopictus mosquitoes in Potosi, Missouri. This evidence indicates that this species may serve as an arbovirus vector in the United States. The urban-suburban distribution, aggressive biting behavior, and broad viral susceptibility of Ae. albopictus may lead to the transmission of viruses of known public health importance and perhaps of viruses hitherto not transmitted to humans because of the feeding pattern of their usual vectors.     

Aedes aegypti: origin of a "new" chromosome from a double translocation heterozygote

An apparent enhancement of crossing-over occurs in the region common to two translocated chromosomes derived from two different reciprocal translocations in the yellow-fever mnosquito, Aedes aegypti. A "new" chromosome containing parts of all three linkage groups is created through crossing-over. In a reversible process, two haploid translocated sets in the double translocation heterozygote produce a new, normal chromosome. set and vice versa in alternating generatiots.     

Genome sequence of Theileria parva, a bovine pathogen that transforms lymphocytes

We report the genome sequence of Theileria parva, an apicomplexan pathogen causing economic losses to smallholder farmers in Africa. The parasite chromosomes exhibit limited conservation of gene synteny with Plasmodium falciparum, and its plastid-like genome represents the first example where all apicoplast genes are encoded on one DNA strand. We tentatively identify proteins that facilitate parasite segregation during host cell cytokinesis and contribute to persistent infection of transformed host cells. Several biosynthetic pathways are incomplete or absent, suggesting substantial metabolic dependence on the host cell. One protein family that may generate parasite antigenic diversity is not telomere-associated.     

Lethal effects of synthetic juvenile hormone on larvae of the yellow fever mosquito, Aedes aegypti

Emergence of adult mosquitoes is blocked after the addition of 1 part of crude synthetic juvenile hormone to 100,000 parts water. Development is arrested at stages ranging from pupae to fully formed pharate adults incapable of escaping from the pupal exuvium. Fourth-stage larvae just prior to metamorphosis are most sensitive: 40 percent were killed after being exposed for 1 dayto 1 part juvenile hormone in 2 million parts water. The active material also inhibits the hatching of mosquito eggs.     

Genome sequence of a polydnavirus: insights into symbiotic virus evolution

Little is known of the fate of viruses involved in long-term obligatory associations with eukaryotes. For example, many species of parasitoid wasps have symbiotic viruses to manipulate host defenses and to allow development of parasitoid larvae. The complete nucleotide sequence of the DNA enclosed in the virus particles injected by a parasitoid wasp revealed a complex organization, resembling a eukaryote genomic region more than a viral genome. Although endocellular symbiont genomes have undergone a dramatic loss of genes, the evolution of symbiotic viruses appears to be characterized by extensive duplication of virulence genes coding for truncated versions of cellular proteins.     

Effect of DDT on Free Amino Acids of Susceptible and DDT-Resistant Aedes aegypti Larvae

The exposure of mosquito larvae (Aedes aegypti L.) to LC(50) concentrations of DDT for various periods of time resulted in a selective increase in the alanine level of a DDT-resistant strain after 4 to 8 hours' contact with the insecticide, whereas the concentration of this amino acid in a susceptible strain remained comparatively low.     

The Genome sequence of the SARS-associated coronavirus

We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)-associated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses. The genome sequence will aid in the diagnosis of SARS virus infection in humans and potential animal hosts (using polymerase chain reaction and immunological tests), in the development of antivirals (including neutralizing antibodies), and in the identification of putative epitopes for vaccine development.     

生防蜡样芽胞杆菌Bacillus cereus 905基因组测序及分析

为深入研究蜡样芽胞杆菌905(Bacillus cereus 905)的促生防病机制以及为进一步优化该菌株提供遗传学信息,采用454焦磷酸测序技术对B.cereus 905基因组进行了测序,并使用相关软件对测序数据进行了基因组拼接、基因功能预测与注释、基因本体分析(GO)、直系同源基因簇(COG)聚类分析以及共线性分析。结果表明:B.cereus 905基因组草图序列大小约为5.39 Mb,GC含量35.05%,由127个片段重叠群组成;该序列已提交GenBank数据库,登录号为LSTW00000000;分析发现菌株905的基因组与其他蜡样芽胞杆菌的基因组有显著的共线性关系;菌株905基因组中存在相当数量的与促生防病功能相关的基因。本研究通过对B.cereus 905基因组的测序为该菌株的优化提供了序列信息。     

A novel mode of arbovirus transmission involving a nonviremic host

In nature, infected and uninfected arthropod vectors often feed together on an animal. In mimicking this scenario in the laboratory, uninfected vectors were found to acquire virus while cofeeding on the same host as infected vectors. However, the vertebrate host on which they fed did not develop detectable levels of virus in its blood. These observations were made with Thogoto virus, an influenza-like virus of medical and veterinary significance. Rhipicephalus appendiculatus ticks were used as the vector and guinea pigs as the vertebrate host. The results demonstrate that a vertebrate that is apparently refractory to infection by an arthropod-borne virus can still play an important role in the epidemiology of the virus, and they suggest a novel mode of arthropod-borne virus transmission.     

Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.     

基于支持向量机的DNA序列分类系统的设计与实现

针对传统统计方法进行DNA序列分类时要求DNA序列样本的概率分布函数已知，但多数情况下概率分布函数未知这一问题，采用支持向量机这一新的机器学习方法对DNA序列进行分类；以VB和Matlab为主要工具开发了基于支持向量机的DNA序列分类系统。结果表明：该系统能够动态选择DNA训练样本、待测试样本．以及支持向量机模型中的参数，并根据用户的指定条件动态输出计算结果；对于预测一批已知正确分类答案的DNA序列，系统能够自动统计识别率，以观察参数变化对于算法执行结果的影响。支持向量机能够在概率分布函数未知的条件下对DNA序列进行分类。     

籼稻GAD基因的克隆、序列分析及其植物表达载体构建

[目的]克隆籼稻谷氨酸脱羧酶(GAD)基因的全长cDNA,并进行序列分析和植物表达载体构建,为改良水稻的营养保健品质奠定基础.[方法]根据已知植物GAD基因的保守区域设计引物,以高GABA籼稻品系“新-9-4”的胚芽为材料,利用RT-PCR和RACE技术克隆GAD基因的全长cDNA;扩增其编码序列,构建双T-DNA植物表达载体.[结果]扩增获得长1962 bp的籼稻GAD基因全长cDNA(OsiGAD),包含1479 bp的开放阅读框,编码492个氨基酸.OsiGAD与已报道的水稻GAD基因OsGAD1、OsGAD2、OsGAD3的核苷酸序列同源性分别为67.1%、69.4%、98.3%,推导氨基酸序列的同源性分别为77.6%、70.1%、100.0%.OsiGAD蛋白序列具有磷酸吡哆醛结合位点和与钙调蛋白结合的C端延伸区域;构建了其具有水稻胚乳特异表达特性的双T-DNA植物高效表达载体pCDMAR-OsiGAD-hpt,选择标记基因和OsiGAD-因分别位于此载体的两个不同T-DNA区.[结论]克隆获得的籼稻GAD基因OsiGAD长1962 bp,并成功构建了其双T-DNA植物高效表达载体.     

大熊猫自然感染细小病毒的血清学调查

建立一种检测大熊猫血清中犬细小病毒 (canine parvovirus,CPV)抗体的间接酶联免疫吸附剂测定(enzyme linked immunosorbent assay,ELISA)方法。

以大熊猫源CPV DNA为模板,利用PCR扩增VP2基因,再用原核表达系统对VP2基因进行表达,经纯化后的蛋白作为ELISA包被抗原;制备并纯化兔抗大熊猫IgG,采用辣根过氧化物酶(horseradish peroxidase,HRP)标记作为间接ELISA酶标二抗,通过棋盘法确定抗原包被质量浓度及血清稀释度等条件,并评估建立方法与商业试剂盒检测样品结果的符合率。

原核表达成功获得约70 ku的VP2蛋白,将其作为间接ELISA包被抗原,抗原最佳包被质量浓度为2.0 μg/mL,血清最佳稀释度为1∶400,用该方法进行检测血清样品时OD₄₅₀≥0.258为阳性,反之为阴性。采用建立的ELISA方法检测大熊猫血清样本阳性率为60.0%,高于商业化检测试剂盒检测的阳性率(52.5%),两者总符合率达到87.5%。

本研究首次建立了基于大熊猫源CPV VP2蛋白为抗原、自制HRP标记兔抗大熊猫IgG为酶标二抗的间接ELISA方法,该方法特异性强、灵敏性较高、重复性好,为大熊猫血清中CPV抗体的检测提供了技术支持。

     

猪TPST1基因的克隆、序列分析及真核表达载体的构建

酪氨酸硫化转移酶(Tyrosylrotein sulfotransferase,TPST)在酪氨酸硫化修饰过程中起调节作用.试验参照人、鼠、牛等动物的TPST1 mRNA全长序列设计引物,通过电子克隆结合RT-RCR的方法首次克隆获得包括完整CDS区的猪TPST1基因cDNA序列(HQ439987),分析其核苷酸序列及...     

Genome sequence diversity and clues to the evolution of variola (smallpox) virus

Comparative genomics of 45 epidemiologically varied variola virus isolates from the past 30 years of the smallpox era indicate low sequence diversity, suggesting that there is probably little difference in the isolates' functional gene content. Phylogenetic clustering inferred three clades coincident with their geographical origin and case-fatality rate; the latter implicated putative proteins that mediate viral virulence differences. Analysis of the viral linear DNA genome suggests that its evolution involved direct descent and DNA end-region recombination events. Knowing the sequences will help understand the viral proteome and improve diagnostic test precision, therapeutics, and systems for their assessment.     

Anopheles hackeri,a vector of Plasmodium knowlesi in Malaya

Anopheles hackeri, a mosquito commonly found breeding in nipa palm leaf bases along the Malayan coast, was demonstrated to be infected with Plasmodium knowlesi by the inoculation of sporozoites into an uninfected rhesus monkey. This was the first demonstration of a natural vector of any monkey malaria.     

禽源衣原体主要外膜蛋白基因的克隆与序列分析

根据GenBank中收录的鹦鹉热衣原体主要外膜蛋白(MOMP)基因序列设计合成1对引物,以禽源鹦鹉热衣原体基因组为模板,应用PCR扩增MOMP基因,将其克隆到pUCm-T载体上,并进行序列分析。结果显示,本株禽源鹦鹉热衣原体MOMP编码基因全长为1176 bp,与国外报道的火鸡鹦鹉热衣原体TT3株的MOMP基因同源性为91.9%,与鹦鹉鹦鹉热衣原体6BC株MOMP基因的同源性为83.1%。