苯甲（乙）腈类化合物理化参数的统计和筛选

本文对20个芳香腈化合物的理化参数作了统计分析,得到了乙腈基中—CH_2—基因的电子效应常数为0.2,建立了水解速率常数k与取代基电子效应常数σ的回归方程,pk=5.89,9—2.144σ(R=-0.957,n=20),根据各化合物的因子得分和实验设计方法为生物试验挑选出了5个有代表性的化合物。     

我国化肥施用量及其可能污染的时空分布特征

近年来，随着化肥施用量的增加，由化肥污染所引起的环境问题逐渐被人们所认识。文章利用我国各省历年主要农作物播种面积和化肥用量资料，提出了化肥施用量评价指数。我国总的化肥施用量没有超过适宜施用量；氮肥实际施用量基本接近于适宜施用量，而磷肥、钾肥的实际施用量严重不足。但对全国各省情况的研究表明，东部地区的氮肥施用量普遍超过或接近于适宜施用量，而中西部地区的氮肥施用量普遍小于适宜施用量；各省磷肥和钾肥的施用量普遍严重不足。因此，应降低东部的氮肥用量以减少污染，同时增加中西部的氮肥施用量。全国各省均应增加磷、钾肥施用量，调整氮、磷、钾肥的比例，有计划地安排我国氮、磷、钾肥的施用量及合理比例，从化肥污染的源头减少化肥污染。     

一种经济、简单的微生物基因组DNA的提取方法

获得一定浓度和纯度的DNA是进行分子生物学研究的基础。破解细胞壁与细胞膜是获得基因组DNA的前提，而蛋白质和核酸物质的分离是获得高质量DNA产物的关键。目前，主要采用的破壁方法有：冷冻研磨法、溶菌酶法、EDTA测等，这些方法一般采用复杂的裂解液体系，并借助蛋白酶K和RNA酶的帮助来获得高质量的抽提产物。由于细胞裂解体系不仅配制十分麻烦，而日部分药品有毒操作危险性大，此外部分药品及相关酶试剂价格昂贵。本文充分利用DNA在不同温度下自身可变性与复性的特性和在高盐与高温条件下蛋白质能够变性并沉淀。以无菌的SDS（c／c=20％）和NaCl（c/c=8％）的混合液作裂解体系，在沸水浴中破壁膜并使得部分的蛋白质变性和DNA变性并得到初步分离；随后在60℃和72℃水浴中使变性的DNA复性和重新凝聚，同时让RNA、蛋白质和细胞壁碎片等杂质降解或沉淀，从而获得高质量的DNA产物。     

The effects of different carbon sources on microbial mediation of arsenic in arsenic-contaminated sediment

Changes in speciation and mobility of As by indigenous bacteria in As-contaminated sediments (339 mg/kg) from an abandoned Au–Ag mine area in Korea were investigated after biostimulation with a variety of carbon sources, including acetate, lactate and glucose in batch experiments. Sequential extraction analysis designed to determine the form of As occurrence revealed that 40 and 47% of As were present in the sediment as Fe-associated and residual fractions, respectively. After 22-day incubation with acetate and lactate, the presence of indigenous bacteria increased the amount of total dissolved As from both Fe-associated and residual fractions in the sediment. More than 99% of dissolved As existed as As(V) in biotic slurries in contrast to sterile controls (less than 50% of total dissolved As), which indicated that indigenous bacteria transformed some dissolved As(III) to As(V). In real environments, depending on the pH, microbially-produced aqueous As(V) may be either immobilized through adsorption or reduced to As(III) after migration to the anoxic subsurface.     

海洋假单胞杆菌QD80低温碱性蛋白酶的化学修饰

海洋假单胞杆菌QD80低温碱性蛋白酶(QDAPr)具有良好的低温适应性,且与常见的增稠剂及表面活性剂有良好的配伍性.因此该蛋白酶在日用化学领域,尤其是低温洗涤领域,具有广泛的应用价值.为研究其结构与功能之间的关系,用EDC、PMSF、N-AI、2,3-丁二酮等8种化学修饰剂修饰该低温碱性蛋白酶,然后检测残余酶活力,借以研究酶分子中氨基酸侧链基团与酶活性中心的关系.结果表明,羧基、丝氨酸、ε-氨基、巯基等残基与酶活性无关;而色氨酸、组氨酸、酪氨酸残基侧链的化学修饰引起酶活性的大幅度下降,说明色氨酸、组氨酸、酪氨酸残基是酶活力所必需的基团.精氨酸残基侧链的化学修饰引起酶活性的轻微下降,说明精氨酸对酶活性具有一定贡献,但不处于活性中心.图5表2参18     

Uptake and metabolism of [<Superscript>14</Superscript>C]rinderine and [<Superscript>14</Superscript>C]retronecine in leaf-beetles of the genus <Emphasis Type="Italic"> Platyphora</Emphasis> and alkaloid accumulation in the exocrine defensive secretions

Summary. Sequestration and processing of pyrrolizidine alkaloids (PAs) by leaf beetles of the genus Platyphora were investigated. Tracer experiments with labeled alkaloids were performed with P. eucosma feeding on Koanophyllon panamense (Asteraceae, tribe Eupatorieae). P. eucosma catalyzes the same reactions previously demonstrated for P. boucardi specialized to Prestonia portobellensis (Apocynaceae): (i) epimerization of rinderine to intermedine; (ii) esterification of retronecine yielding insect-specific PAs; (iii) efficient transport of the PAs as free bases into the defensive secretions. P. bella feeding on Tournefortia cuspidata (Boraginaceae) shows the same sequestration behavior and ability to synthesize the specific retronecine esters. P. ligata, a species phylogenetically closely related to the PA adapted species and clustering in the same clade, but feeding on a host plant devoid of PAs, feeds easily on PA treated host-plant leaves, but does not sequester or metabolize PAs. P. kollari a species clustering outside the PA clade refused to feed on its food-plant leaves painted with PAs. The results are discussed in relation to host-plant selection of the PA adapted species and the role of PAs in chemical defense. Received 20 September 2002; accepted 18 November 2002.     

Responses of three mouse species to deterrent chemicals in the monarch butterfly. II. Taste tests using intact monarchs

Summary Peromyscus melanotis is the only one of three mouse species that eats monarch butterflies at their overwintering sites in Mexico. I tested two hypotheses: 1)P. aztecus avoids monarchs because of a bitter taste aversion to cardiac glycosides (CGs) and an inability to reject CG-rich body parts; 2)Reithrodontomys sumichrasti avoids monarchs principally because of a bitter taste aversion to the CGs. None of the species are sensitive to the toxic effects of ingested CGs. Feeding responses of laboratory-reared mice of each species to monarchs with low, medium and high CG concentrations were compared. BothP. aztecus andR. sumichrasti ate significantly fewer of all three types of monarchs thanP. melanotis. ForP. aztecus andR. sumichrasti, the number of monarchs eaten decreased with increasing CG concentration, whereas forP. melanotis, the number remained constant.Peromyscus melanotis andR. sumichrasti developed a feeding technique for rejecting the CG-laden cuticular material, which reduced the bitterness of ingested monarch material. However,R. sumichrasti displayed the technique significantly less often thanP. melanotis; andP. aztecus never developed it. I conclude that high taste sensitivity to CGs and less versatile food handling preventP. aztecus andR. sumichrasti from overcoming the monarch's chemical defenses.     

Allelochemical effects of ergoline alkaloids fromIpomoea parasitica onHeliothis virescens

Lysergol, elymoclavine and three other van Urk-positive alkaloids were identified by 2D chromatography in the seed extract ofIpomoea parasitica. The presence of the same ergoline alkaloids was also demonstrated in vegetative tissue ofI. parasitica. Heliothis virescens larvae reared on a diet containing an alkaloid extract ofI. parasitica showed an increase in the consumption index and a reduction in the effiency of conversion of food. No difference was observed in the approximated digestibility. The percentages of pupation and emergence were reduced and the malefemale ratio was altered in insects fed on a diet containing the alkaloid extract ofI. parasitica or lysergol. The increases in the concentration of ergoline alkaloids inI. parasitica at the seedling stage and at flowering support the theory that these compounds play a defensive role against herbivory in the plant.     

火力发电厂灰渣场地理化性质对植物生长的影响

经实地考察分析 ,对芜湖火力发电厂灰渣场地理化性质和植物生长的关系进行了研究。结果表明 ,芜湖发电厂灰渣场地自然定居的植物仅 30种 ,大部分定居物种是适于风力传播的繁殖体 ,它和渣场周边的植物繁殖体源有重要关系。灰渣场地物理性质不良、养分不平衡而贫瘠和重金属浓度过高是限制植物定居的主要因素。     

利用垃圾堆肥改良水稻土I:对水稻土物理化学性状的影响

根据上海市农业产业结构调整过程中对土质的要求，本文从资源化利用上海市城市生活垃圾的角度出发，将自然堆置多年的垃圾堆肥应用于土壤改良．由于垃圾堆肥质地粗松，含有较高的营养成分，同时考虑到水稻土对垃圾堆肥的承纳量，本实验设计了0、7．5、15、22．5kgm^-2 4个垃圾堆肥施用剂量，经过一个完整的生长季节后采集土壤样品进行理化分析．结果表明，相较对照小区(0kg m^-2)，施用垃圾堆肥可以有效地改良水稻土的物理化学性状：有机质、全N、全P、碱解N和速效P的含量分别提高5％—240％，土壤中细砂含量升高，粘粒含量下降．而且这种改良的效果随着垃圾堆肥施用量的增加而增加．在不同耕作深度上，以0-10cm土层的效果最佳，10—20cm次之，20—40cm最低．本实验结果表明，垃圾堆肥不仅是上海市水田旱作土壤的有效改良添加剂，而且是解决城市生活垃圾出路的一条有效途径．表2参7