A survey of the socially parasitic ant generaEpimyrma Emery, 1915 andChalepoxenus Menozzi, 1922 in Italy (Hymenoptera,Formicidae, Myrmicinae)

Summary An up-to-date synthesis is presented of the available faunistic and biological data concerning the Italian species belonging to the socially parasitic ant generaEpimyrma Emery andChalepoxenus Menozzi.The first known populations ofE. corsica (Emery) andE. stumperi (Kutter) in Italy were discovered in the Lucretili mountains (Latium) and in Alto Adige, the former species being previously recorded only in Corsica and Dalmatia (Yugoslavia), the latter in the French and Swiss Alps.The first records ofE. ravouxi (André),E. kraussei (Emery) andC. muellerianus (Finzi) in central Italy are presented. Since no species of either genera has ever been collected in Italy in the area between the Po valley and Calabria, these new records are of great interest.Maps, showing the currently known distribution of each taxon in Italy, are provided.     

On the relative importance of specific and non-specific approaches to oral microbial adhesion.

In this paper, it is suggested that specificity and non-specificity in (oral) microbial adhesion are different expressions for the same phenomena. It is argued that the same basic, physicochemical forces are responsible for so-called 'non-specific' and 'specific' binding and that from a physico-chemical point of view the distinction between the two is an artificial one. Non-specific interactions arise from Van der Waals and electrostatic forces and hydrogen bonding, and originate from the entire cell. A specific bond consists of a combination of the same type of Van der Waals and electrostatic forces and hydrogen bonding, now originating from highly localized chemical groups, which together form a stereochemical combination. The absence or presence of specific receptor sites on microbial cell surfaces must therefore be reflected in the overall, non-specific surface properties of cells as well. This point is illustrated by showing that glucan-binding lectins on mutans streptococcal strains may determine the pH dependence of the zeta potentials of these cells. When studying microbial adhesion, a non-specific approach may be better suited to explain adhesion to inert substrata, whereas a specific approach may be preferred in case of adhesion to adsorbed protein films. Adhesion is, however, not as important in plaque formation in the human oral cavity as is retention, because low shear force periods, during which adhesion presumably occurs, are followed by high shear force periods, during which adhering cells must withstand these detachment forces. Evidence is provided that such detachment will be through cohesive failure in the pellicle mass, the properties of which are conditioned by the overall, non-specific substratum properties. Therefore, in vivo plaque formation may be more readily explained by a non-specific approach.     

Intrinsic fluorescence of the bacterial copper-containing protein amicyanin

The fluorescence properties of the single tryptophanyl residue present in amicyanin from Thiobacillus versutus are very similar to those of azurin from Pseudomonas aeruginosa and other mononuclear blue copper proteins. The emission maximum is well structured and centered at 318 nm. The quantum yield is strongly affected by the presence of copper, the removal of which is accompanied by a more than sixfold increase in fluorescence, without change in shape. The fluorescence decay of holo-amicyanin is heterogeneous with a longer component of 5.7 ns and a shorter one of 0.7 ns accounting for 90% of the total emitting molecules. Copper-free amicyanin shows instead a single exponential decay (3.3 ns) of intrinsic fluorescence. This lifetime decreases as the temperature increases as does the longer lifetime component of holoamicyanin.     

温度对干旱、盐胁迫下两种黄芪属种子萌发和幼苗生长的影响

为探讨温度对干旱、盐胁迫下黄芪属种子萌发和幼苗生长特性的影响,以黄芪属蒙古黄芪和扁茎黄芪2种种子为研究对象,纯净水处理为对照组,NaCl、PEG处理为实验组,设置4个渗透势水平(0、-0.1、-0.3、-0.5 MPa),置于5种不同的温度(10、15、20、25、30 ℃)下,每日观察并记录两种种子萌发和幼苗生长情况。结果表明：旱盐胁迫下蒙古黄芪和扁茎黄芪种子萌发最适宜的温度分别为25和20 ℃左右;蒙古黄芪耐高温不耐低温,而扁茎黄芪恰恰相反;但25和20 ℃均适宜两种幼苗生长,包括胚根、胚轴和子叶的生长。蒙古黄芪各处理组(除未发芽的种子)的平均发芽时间都比扁茎黄芪长;NaCl胁迫程度的增加使得两种种子的最终发芽率降低,但蒙古黄芪的耐盐性高于扁茎黄芪;随着PEG胁迫程度的增加,二者的发芽均受到抑制,甚至会出现完全不萌发,但扁茎黄芪的耐旱性高于蒙古黄芪;在相同的渗透势时,尤其是-0.5 MPa,PEG比NaCl对两种种子的影响大;交互胁迫作用下,随着渗透势的增加两种幼苗的鲜重、干重以及胚根、胚轴、子叶的长和宽变化较大;利用Design Expert软件预测发现：温度25 ℃、NaCl渗透势为-0.1 MPa,温度24 ℃、PEG渗透势为-0.04 MPa的处理是蒙古黄芪种子萌发和幼苗生长达到最优化的组合;而扁茎黄芪最优化的组合则为23 ℃下NaCl渗透势为-0.07 MPa的处理,20 ℃下PEG渗透势为-0.13 MPa的处理。     

Acoustic modes and nonbonded interactions of the double helix

Observations of acoustic velocities in DNA fibers have been used to refine nonbonded force constants for the DNA double helix. Long-range forces are found to be needed for A conformation and are likely to dominate in B conformation as well. The acoustic dispersion curves are described and calculated. A correction due to the effects of water is calculated. The effect of nonbonded interaction on other vibrational modes is calculated.     

中华蜂体内放线菌的分离、多样性及抗菌活性研究

【目的】探索药用昆虫中华蜂(Apis cerana cerana Fabricius)体内可培养放线菌的分离方法,研究其物种多样性及抗菌活性,挖掘更多微生物资源。【方法】选用7种分离培养基对中华蜂样品体内放线菌进行分离;通过采用16S rRNA PCR-RFLP和16S rRNA基因序列分析方法研究其多样性;选用4种致病菌对菌株进行抗菌活性初探。【结果】共分离得到180株放线菌,根据菌落的形态和细胞特征观察结果,从中选取84株作为代表菌株,其分属于3个目、4个科中的4个属,其中6株为潜在新种;最适的表面消毒方法:浓度为0.2%的Cl O2(二氧化氯)作为消毒剂,作用60 s;拮抗实验显示,31.0%、48.8%、27.4%、16.7%的代表菌株分别对大肠杆菌、枯草芽孢杆菌、玉米弯孢病菌、西瓜枯萎病菌有不同程度的抗菌活性,71.4%的代表菌株对至少一种病原菌有拮抗作用。【结论】分离方法的选择对昆虫体内放线菌的分离效果影响较大;中华蜂体内放线菌具有丰富的多样性,展现出很好的抗菌活性,表明其在发现新型生物活性物质中具有很大的潜力。     

我国苏云金杆菌研究60年

综述了我国近60年来的苏云金杆菌研究进展,包括资源收集及分类鉴定、Bt新基因的发掘及组学研究、病理学与作用机制、毒力测定、产品标准化、产业化,并就Bt生物农药存在的问题及改善途径进行了探讨。     

基于DSSAT模型对豫北地区夏玉米灌溉制度的优化模拟

合理的灌溉制度是提高农业水资源利用效率、保证夏玉米高产稳产的前提。采用农业技术转化决策系统(DSSAT,Decision Support System for Agrotechno1ogy Transfer)探究了河南省北部地区夏玉米不同降水年型下的最优灌溉制度。经过参数的校正和验证,归一化均方根误差(nRMSE)、均方根误差(RMSE)和一致性指数(d)均表现出模拟值与实测值的吻合度很好,DSSAT-maize模型可以准确模拟夏玉米物候期、地上部分生物量、产量和土壤水分状况。然后基于模型模拟了不同灌溉处理下的夏玉米生产潜力,从而评估夏玉米缺水量,并对比分析不同生育时期灌水对产量的影响确定最优灌溉时期,综合考虑产量和水分利用效率确定最优灌溉制度。结果表明:夏玉米生长季的缺水量年际间差异显著,多年平均值为38.91 mm,波动范围为0—193.03 mm。在丰水年,不需要灌溉;在平水年,开花期灌水30 mm;在枯水年,开花期和灌浆期灌水50 mm;在特别干旱年,苗期、拔节期和开花期至少灌水180 mm。优化的灌溉制度下丰水年、平水年和枯水年的WUE达到最高且产量分别占其最高产量的100%、99.72%和97.89%,实现了作物高产节水协同提高的目标。     

新疆典型蝗虫适生区分布预测

新疆草原面积广阔,农牧业地位突出,蝗灾对当地经济、生态威胁很大,近年新疆极端天气日渐频发,蝗灾监测与防治任务艰巨。以意大利蝗、西伯利亚蝗和亚洲飞蝗为代表的蝗虫数据为基础,综合考虑对蝗虫各生命周期有重要影响的环境因素,运用BIOCLIM模型、领域模型(DOMAIN)、马氏距离模型(MAHAL)、广义线性模型(GLM)、随机森林模型(RF)、提升回归树模型(BRT)、支持向量机模型(SVM)、最大熵模型(MaxEnt)等八种经典物种分布模型及集成模型对新疆典型蝗虫适生区展开了预测。结果表明：(1)不同模型对新疆典型蝗虫适生区预测存在差异,其中DOMAIN最差(曲线下面积(AUC)=0.688,真实技巧统计(TSS)=0.301),而提升回归树(BRT)最佳(AUC=0.920,TSS=0.910),基于BRT、SVM和MaxEnt 3个集成模型预测的新疆蝗虫适生区可靠性更高;(2)新疆典型蝗虫不同等级适生区面积约56.844万km²,占新疆总面积的36%,其中高适生区面积16.568万km²;(3)新疆典型蝗虫适生区主要集中于北疆阿勒泰、塔城地区...