新烟碱类和大环内酯类杀虫剂对四种赤眼蜂成蜂急性毒性和安全性评价

为了明确新烟碱类和大环内酯类杀虫剂对天敌赤眼蜂Trichogramma spp.的影响, 在室内采用药膜法测定了其对稻螟赤眼蜂Trichogramma japonicum Ashmead、 亚洲玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen、 拟澳洲赤眼蜂Trichogramma confusum Viggiani和广赤眼蜂Trichogramma evanescens Westwood成蜂的急性毒性, 并进行了安全性评价。急性毒性测定结果表明： 在测定的新烟碱类药剂中, 噻虫嗪对拟澳洲赤眼蜂和稻螟赤眼蜂表现出最高的急性毒性, 其LC₅₀分别为0.24 (0.21~0.27) 和0.40 (0.37~0.44) mg a.i./L; 其次为烯啶虫胺, 该药剂对上述两种赤眼蜂的LC₅₀分别为0.83 (0.74~0.96) 和0.72 (0.65~0.80) mg a.i./L; 而吡虫啉对亚洲玉米螟赤眼蜂和拟澳洲赤眼蜂的毒性最低, 其LC₅₀分别为502.13 (459.80~549.62)和752.62 (687.51~828.63) mg a.i./L。在测定的大环内酯类药剂中, 阿维菌素对稻螟赤眼蜂的急性毒性最高, 其LC₅₀为0.49 (0.46~0.65) mg a.i./L, 而甲氨基阿维菌素苯甲酸盐对拟澳洲赤眼蜂表现出最低的急性毒性, 其LC₅₀为21.76 (19.59~24.40) mg a.i./L。安全性评价结果表明, 吡虫啉、 啶虫脒、 氯噻啉和甲氨基阿维菌素苯甲酸盐对4种赤眼蜂为低风险~中等风险性, 安全性系数为0.57~23.54; 噻虫啉和依维菌素对4种赤眼蜂却为中等风险~高风险性, 安全性系数为0.16~3.45; 而烯啶虫胺、 噻虫嗪和阿维菌素对4种赤眼蜂为高风险~极高风险性, 安全性系数为0.01~0.15。本研究测定的大部分杀虫剂对赤眼蜂都有一定的急性毒性风险。因此, 在害虫综合治理中应谨慎使用新烟碱类和大环内酯类杀虫剂尤其是烯啶虫胺、 噻虫嗪和阿维菌素, 以免造成对赤眼蜂的大量杀伤。     

Molecular biology of plasma membrane redox enzymes: A survey of current knowledge

Summary Despite a large body of evidence for enzymatic activities and physiological functions of plasma membrane redox function, few of these enzymes have been characterized in terms of molecular biology. Examples for these with at least some molecular data up to complete sequences, membrane topology and binding sites for substrates and coenzymes or prosthetic groups are NADH-ferricyanide reductase of Ehrlich ascites membranes, NADH-coenzyme Q reductase of liver, NADH oxidase ectoenzyme of liver and HeLa (and possibly other) cells, protein disulfide isomerase which is widespread, and relatives thereof, as well as cytochromes P-450 andb ₅₅₈, NADPH oxidase of fat and thyroid cells and fat cell amine oxidase. Ferricyanide reductase and coenzyme O reductase may be identical, but NADH oxidase ectoenzyme is distinct and possibly functions also as a disulfide and a copper reductase. On the other hand, the plasma-membrane-located protein disulfide isomerase (PDI), despite its similar enzymatic activity, is completely different from the ectooxidase. The latter is shed from the membrane into the surrounding medium by proteolysis, whereas PDI is not an integral membrane protein and is secreted intact. Another disulfide reductase has been demonstrated in THP-1 cells, which again is totally different from the former two. It turns out that enzymatic activities are insufficient to describe redox enzymes. Special forms of cytochrome P-450 can be induced to expression at the cell membrane of liver, where they are transported by the cytoskeleton-associated secretory pathway. Why some isoforms are expressed at the surface and some are not is not yet clear. Cytochromeb ₅₅₈, the flavocytochrome of neutrophils, is described in other cells too, but there are different isoforms, which are genetically distinct. A relative has also been identified in duodenal cells, where it functions as a ferric reductase involved in iron absorption. NADPH oxidase of fat cells has very similar properties, but the identity is unproved, whereas thyroid oxidase is a non-heme protein which is calcium-sensitive and does not need assembly of subunits for activation. Finally, fat cell membranes also possess a quinone-containing amine-oxidase which may be involved in signaling of glucose-transport regulation, as it is also found in GLUT4-containing vesicles. However, the physiological connection has yet to be demonstrated.     

Selenium-containing tRNAs from Clostridium sticklandii. Cochromatography of seleno-tRNA I with l-valyl-tRNA

It has been previously shown that Clostridium sticklandii specifically synthesized three readily separable ⁷⁵Se-labeled tRNAs, designated seleno-tRNAs I, II and III, and the partially purified seleno-tRNA II cochromatographed with l-prolyl-tRNA on DEAE-Sephadex A-50 (Chen, C.S. and Stadtman, T.C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1403–1407). In the present study a highly purified ⁷⁵Se-labeled tRNA I was obtained by chromatography on benzoylated DEAE-cellulose, DEAE-Sephadex A-50 and Sepharose 4B. The ⁷⁵Se-labeled tRNA I cochromatographed with an l-valine-accepting species on DEAE-Sephadex A-50 and Sepharose 4B. Addition of a 285-fold molar excess of unlabeled l-valine to the l-valine acceptor activity assay mixture markedly decreased the amount of l-[¹⁴C]valine bound to seleno-tRNA I.     

Identification of an insertion sequence, IS1081, in Mycobacterium bovis

Abstract: An insertion sequence, IS1081, in the genome of Mycobacterium bovis has been identified and sequenced. It is 1324 bp long with 15 bp inverted repeat ends and contains a large ORF. There are six copies of IS1081 in the genome of M. bovis and the element is also present in Mycobacterium tuberculosis . IS1081 is not closely related to other DNA elements described in actinomycetes but its putative transposase bears some resemblance to that of IS256 from Staphylococcus aureus . IS1081 may be useful for genetic manipulations and for developing a diagnostic test for bovine tuberculosis based on the polymerase chain reaction.     

Measurement of the relative electron-transport capacity of Photosystem I and Photosystem II in spinach chloroplasts

The ratio of Photosystem (PS) II to PS I electron-transport capacity in spinach chloroplasts was compared from reaction-center and steady-state rate measurements. The reaction-center electron-transport capacity was based upon both the relative concentrations of the PS II_α, PS II_β and PS I centers, and the number of chlorophyll molecules associated with each type of center. The reaction-center ratio of total PS II to PS I electron-transport capacity was about 1.8:1. Steady-state electron-transport capacity data were obtained from the rate of light-induced absorbance-change measurements in the presence of ferredoxin-NADP⁺, potassium ferricyanide and 2,5-dimethylbenzoquinone (DMQ). A new method was developed for determining the partition of reduced DMQ between the thylakoid membrane and the surrounding aqueous phase. The ratio of membrane-bound to aqueous DMQH₂ was experimentally determined to be 1.3:1. When used at low concentrations (200 μM), potassium ferricyanide is shown to be strictly a PS I electron acceptor. At concentrations higher than 200 μM, ferricyanide intercepted electrons from the reducing side of PS II as well. The experimental rates of electron flow through PS II and PS I defined a PS II/PS I electron-transport capacity ratio of 1.6:1.     

Effect of Alkylsilyl Side‐Chain Structure on Photovoltaic Properties of Conjugated Polymer Donors

Side‐chain engineering is an important strategy for optimizing photovoltaic properties of organic photovoltaic materials. In this work, the effect of alkylsilyl side‐chain structure on the photovoltaic properties of medium bandgap conjugated polymer donors is studied by synthesizing four new polymers J70 , J72 , J73 , and J74 on the basis of highly efficient polymer donor J71 by changing alkyl substituents of the alkylsilyl side chains of the polymers. And the photovoltaic properties of the five polymers are studied by fabricating polymer solar cells (PSCs) with the polymers as donor and an n‐type organic semiconductor (n‐OS) m‐ITIC as acceptor. It is found that the shorter and linear alkylsilyl side chain could afford ordered molecular packing, stronger absorption coefficient, higher charge carrier mobility, thus results in higher J_sc and fill factor values in the corresponding PSCs. While the polymers with longer or branched alkyl substituents in the trialkylsilyl group show lower‐lying highest occupied molecular orbital energy levels which leads to higher V_oc of the PSCs. The PSCs based on J70 :m‐ITIC and J71 :m‐ITIC achieve power conversion efficiency (PCE) of 11.62 and 12.05%, respectively, which are among the top values of the PSCs reported in the literatures so far.     

西南山区人口空间重组及其对植被的影响——以河流沿线为例

随着城市化的快速推进,山区人口迁出及空间重组成为影响中国山区人地关系的重要因素,这可能对山区植被恢复和生态改善产生巨大影响。基于人口空间数据、河流分布数据和MODIS数据,本文分析了河流沿线人口空间重组情况,以生长季EVI值为表征植被绿度的指标,采用基于像元的趋势分析方法和基于样本的相关分析模型,对2000—2010年间中国西南山区不同级别河流沿线的人口空间变化和植被变化作了系统性分析,并定量研究了人口空间重组与植被变化之间的关系。结果表明:(1)三级及以上河流出现人口往河流沿线聚集的趋势,人口在河流的影响区聚集程度大于对比区。其中,一级和二级河流沿线影响区人口密度增加量比对比区分别高75.9%和42.1%。(2)三级及以上各河流沿线影响区和对比区EVI均呈现出增加的趋势,且影响区增加趋势低于对比区。(3)植被EVI变化趋势与人口密度变化呈负相关关系,河流沿线人口密度增加不利于植被的恢复;河流级别越高,植被EVI变化趋势与人口密度变化的相关性越强。     

Reaction of wild-type and Glu243Asp variant yeast cytochrome c oxidase with O2

We have studied internal electron transfer during the reaction of Saccharomyces cerevisiae mitochondrial cytochrome c oxidase with dioxygen. Similar absorbance changes were observed with this yeast oxidase as with the previously studied Rhodobacter sphaeroides and bovine mitochondrial oxidases, which suggests that the reaction proceeds along the same trajectory. However, notable differences were observed in rates and electron-transfer equilibrium constants of specific reaction steps, for example the ferryl (F) to oxidized (O) reaction was faster with the yeast (0.4 ms) than with the bovine oxidase (~ 1 ms) and a larger fraction Cu_A was oxidized with the yeast than with the bovine oxidase in the peroxy (P_R) to F reaction. Furthermore, upon replacement of Glu243, located at the end of the so-called D proton pathway, by Asp the P_R → F and F → O reactions were slowed by factors of ~ 3 and ~ 10, respectively, and electron transfer from Cu_A to heme a during the P_R → F reaction was not observed. These data indicate that during reduction of dioxygen protons are transferred through the D pathway, via Glu243, to the catalytic site in the yeast mitochondrial oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.     

湖北贝母单鳞片砂培繁殖研究

本文针对湖北贝母生产中存在繁殖系数低的问题,研究了单鳞片砂培繁殖对提高鳞茎繁殖率的效果和原理。试验结果表明:1.单鳞片繁殖率为对照种鳞茎的5—9倍,2.低温(2—10℃)预处理4—8周和暗条件培养,能有效地提高子球形成率,促使子球迅速长大,3.植物激素(6-BA、KT、2,4-D)处理,有利于促进鳞片不定芽原基的分化,繁殖率为种茎繁殖的9—11倍;4.单鳞片繁殖的小鳞茎主要发生在鳞片基部的茎盘上,还可发生在鳞片的远轴面上,但不发生在近轴面。     

Harmonious Compatibility Dominates Influence of Side‐Chain Engineering on Morphology and Performance of Ternary Solar Cells

A growing number of recent studies have demonstrated the substantial impact of the alkyl side chains on the device performance of organic semiconductors. However, detailed investigation of the effect of side‐chain engineering on the blend morphology and performance of ternary organic solar cells (OSCs) has not yet been undertaken. In this study, the performance of ternary OSCs is investigated in a given poly(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)):[6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PTB7‐Th:PC₇₁BM) host set by introducing various small molecule donors (SMDs) with different terminal side‐chain lengths. As expected, the performance of binary OSCs with SMDs depends greatly on the side‐chain length. In contrast, it is observed that all SMD‐based ternary OSCs exhibit almost identical and high power‐conversion efficiencies of 12.0–12.2%. This minor performance variation is attributed to good molecular compatibility between the two donor components, as evidenced by in‐depth electrical and morphological investigations. These results highlight that the alloy‐like structure formed due to the high compatibility of the donor molecules has a more significant effect on the overall performance than the side‐chain length, offering a new guideline for pairing donor components for achieving high‐performance ternary OSCs.