流溪河流域景观空间特征与河流水质的关联分析

人类活动影响或改变流域景观空间结构,并有可能对河流水质产生不同程度的影响,以流溪河流域为研究区,分析流域景观空间格局特征与水质指数之间的相关关系。将流域划分为27个子流域,采集水样分析水质状况,所选用的水质指标有氨氮(NH3-N)、硝态氮-亚硝态氮(NO3-N+NO2-N)、总磷(TP)、化学需氧量(CODCr)。结果表明:1)该流域土地利用结构与水质具有显著相关性,其中居住用地对水质的影响作用最强,林地对河流水质具有净化功能,与水质指标之间的关系表现为负相关,园地与水质指标关系具有不确定性;2)流域景观特征从上游到下游之间表现为城市化增强的梯度,水质状况响应这个梯度变化表现为上游优于下游,人类活动及城市化发展引起的土地利用变化及土地管理方式对水质变化有显著影响;(3)景观破碎度与水质呈现显著正相关性,是影响水质的重要指标,景观聚集程度和斑块形状复杂程度与水质有负相关关系;子流域尺度和河岸带尺度景观空间特征对水质的影响差异不明显。     

条锈菌诱导的抗锈小麦种质的基因表达分析

以条锈菌接种前后的抗条锈病种质N 95175的小麦幼苗叶片为材料,利用抑制消减杂交技术,构建了条锈菌接种初期小麦抗性种质叶片的SSH-cDNA文库。通过对文库中随机选取的50个阳性克隆提取质粒,进行测序,共获得已知功能的EST序列14条,如蛋白激酶、锌指蛋白、细胞色素P 450和OM T 1等抗病相关基因,它们涉及植物的信号传导、转录调控、丙烷代谢途径及防卫反应等方面。     

Detection of human blood by cloth-based enzyme immunoassay of immunoglobulin G

A specific and sensitive assay for the detection of human blood was developed using polyester cloth coated with goat anti-human IgG antibody to capture human IgG, an abundant and stable protein in blood. The captured IgG was detected by the reaction between goat anti-human IgG antibody-peroxidase conjugate and a chromogenic peroxidase substrate. Because the assay is simple and rapid, and permits simultaneous analysis of multiple samples, it has the potential to be used as a forensic test for human blood.     

Excess carotenoids disturb prospective cell-to-cell recognition system in mating responses ofPhycomyces blakesleeanus

Carotenogenic mutants ofPhycomyces, which accumulate excess β-carotene or its intermediates, always failed in zygospore development. No improvement occurred when such mutants were mated together with a helper wild type of the same mating type against the wild type of the opposite mating type. Addition of excess synthesized pheromone, trisporin B, also failed to improve the zygospore development, though the mating response was significantly activated in the early stages and abundant zygophores were formed. Exceptional acceleration of the zygospore development under these experimental conditions occurred in a regulatory albino mutant (carA), which does not accumulate excess intermediate carotenoids. Chemically- or genetically-induced ovarproduction of β-carotene or lycopene also inhibited the zygospore development. These results imply that the zygospore development ofPhycomyces is maximal when the intracellular amount of β-carotene is optimal (=wild type), and that pheromones act mainly in the early stages of mating, while other factors such as the cell-to-cell recognition system may also be involved in the later stages. Intracellular accumulation of excess β-carotene or its intermediates probably disturb such later-stage factors.     

Structural insight into receptor-selectivity for lurasidone

Lurasidone is a novel antipsychotic agent with high affinity for dopamine D₂, 5-hydroxyltryptamine 5-HT_2A, and 5-HT₇ receptors. Lurasidone has negligible affinity for histamine H₁ and muscarinic M₁ receptors, which are thought to contribute to side effects such as weight gain, sedation, and worsening of cognitive deficits. Our interests focus on why lurasidone has such high selectivity for only a part of these aminergic G-protein coupled receptors (GPCRs) and the different binding profile from ziprasidone, which has the same benzisothiazolylpiperazine moiety as lurasidone. In order to address these issues, we constructed structural models of lurasidone–GPCR complexes by homology modeling of receptors, exhaustive docking of ligand, and molecular dynamics simulation-based refinement of complexes. This computational study gave reliable structural models for D₂, 5-HT_2A, and 5-HT₇, which had overall structural complementarities with a salt bridge anchor at the center of the lurasidone molecule, but not for H₁ and M₁ owing to steric hindrance between the norbornane-2,3-dicarboximide and/or cyclohexane part of lurasidone and both receptors. By comparison with the structural models of olanzapine–GPCRs and ziprasidone–GPCRs constructed using the same computational protocols, it was suggested that the bulkiness of the norbornane-2,3-dicarboximide part and the rigidity and the bulkiness of the cyclohexyl linker gave lurasidone high selectivity for the desired aminergic GPCRs. Finally, this structural insight was validated by a binding experiment of the novel benzisothiazolylpiperazine derivatives. This knowledge on the structural mechanism behind the receptor selectivity should help to design new antipsychotic agents with preferable binding profiles, and the established computational protocols realize virtual screening and structure-based drug design for other central nervous system drugs with desired selectivity for multiple targets.     

2-Amino-3-carboxy-1,4-naphthoquinone affects the end-product profile of bifidobacteria through the mediated oxidation of NAD(P)H

Glucose metabolism of bifidobacteria in the presence of 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ), a specific growth stimulator for bifidobacteria, and ferricyanide (Fe(CN)(6)(3-)) as an extracellular electron acceptor was examined using resting cells of Bifidobacterium longum and Bifidobacterium breve. NAD(P)H in the cells is oxidized by ACNQ with the aid of diaphorase activity, and reduced ACNQ donates the electron to Fe(CN)(6)(3-). Exogenous oxidation of NADH by the ACNQ/Fe(CN)(6)(3-) system suppresses the endogenous lactate dehydrogenase reaction competitively, which results in the remarkable generation of pyruvate and a decrease in lactate production. In addition, a decrease in acetate generation is also observed in the presence of ACNQ and Fe(CN)(6)(3-). This phenomenon could not be explained in terms of the fructose-6-phosphate phosphoketolase pathway, but suggests rather that glucose is partially metabolized via the hexose monophosphate pathway. This was verified by NADP(+)-induced reduction of Fe(CN)(6)(3-) in cell-free extracts in the presence of ACNQ. Effects of the ACNQ/Fe(CN)(6)(3-) system on anaerobically harvested cells were also examined. Stoichiometric analysis of the metabolites from the pyruvate-formate lyase pathway suggests that exogenous oxidation of NADH is an efficient method to produce ATP in this pathway.     

Complete Nucleotide Sequence and Genetic Organization of Aichi Virus, a Distinct Member of the Picornaviridae Associated with Acute Gastroenteritis in Humans

The complete nucleotide sequence of a novel enteric virus, Aichi virus, associated with nonbacterial acute gastroenteritis in humans was determined. The Aichi virus genome proved to be a single-stranded positive-sense RNA molecule with 8,251 bases excluding a poly(A) tail; it contains a large open reading frame with 7,302 nucleotides that encodes a potential polyprotein precursor of 2,433 amino acids. The genome contains a 5′ nontranslated region (NTR) with 712 bases and a 3′ NTR with 240 bases followed by a poly(A) tail. The structure of the genome, VPg–5′ NTR–leader protein–structural proteins–nonstructural proteins–3′ NTR–poly(A), was found to be typical of a picornavirus. The VP0-VP3 and VP3-VP1 cleavage sites were determined to be Q-H and Q-T, respectively, by N-terminal amino acid sequence analyses using purified virion proteins. Possible cleavage sites, Q-G, Q-A, and Q-S, which cleave P2 and P3 polyproteins were found to be similar to those of picornaviruses. A dendrogram based on 3D^pol proteins indicated that Aichi virus is genetically distinct from the known six genera of picornaviruses including entero-, rhino-, cardio-, aphtho-, and hepatovirus and echovirus 22. Considering this together with other properties of the virus (T. Yamashita, S. Kobayashi, K. Sakae, S. Nakata, S. Chiba, Y. Ishihara, and S. Isomura, J. Infect. Dis. 164:954–957, 1991), we propose that Aichi virus be regarded as a new genus of the family Picornaviridae.     

凋亡和周期基因芯片研究As2O3对NB4细胞凋亡相关基因表达谱的影响

目的:利用细胞凋亡和周期基因芯片研究As₂O₃作用前后NB4细胞基因表达谱的差异性,寻找As₂O₃诱导NB4细胞凋亡的相关基因并分析其可能机制。方法:流式细胞仪检测细胞凋亡率,抽提对照及诱导组细胞的mRNA,通过逆转录将As₂O₃处理前后的NB4细胞cDNA进行生物素标记,用含269个目的基因的细胞凋亡和周期基因芯片进行杂交,GEArray软件分析,筛选出As₂O₃诱导前后表达有差异的基因。芯片结果用荧光定量聚合酶链反应(realtimepolymerasechainreaction)进行验证。结果:筛选出As₂O₃作用前后表达有差异的基因共100条(占芯片基因总数的37.2%),其中97条(97/100,97%)基因表达上调,3条(3/100,3%)基因表达下调。表达上调的基因主要包括肿瘤坏死因子配体和受体家族、bcl2家族、半胱氨酸家族、DNA损伤检测和P53途径以及细胞分裂周期蛋白和激酶等基因。结论:As₂O₃主要通过上调促凋亡基因表达来诱导NB4细胞凋亡,其中TNFSF15、Apaf1、Caspase3和p16等基因可能参与As₂O₃诱导的NB4细胞凋亡,As₂O₃诱导NB4细胞凋亡的可能机制主要涉及TNF途径、线粒体途径、Caspase途径、细胞周期抑制途径和P53途径等。