昆虫体内抗氧化系统研究进展

昆虫为了减轻和防止活性氧损伤,已形成了复杂的氧化应激机制。可通过酶促如超氧化物歧化酶、过氧化物酶、过氧化氢酶等和非酶促谷胱甘肽、抗坏血酸和胡萝卜素等清除活性氧的系统以清除过量的活性氧。本文论述了昆虫在氧化胁迫下所具有的一套抗氧化系统。对其系统组成抗氧化酶和抗氧化剂的主要成分的抗氧化活性进行了综述。     

食用菌体内抗氧化酶活性影响因素的研究进展

食用菌的菌丝和子实体在正常生长发育中会产生活性氧,但是在环境胁迫下或者贮藏运输中活性氧会大量增加,打破了活性氧的平衡,必须依靠抗氧化酶系对抗其有害作用。介绍了抗氧化酶的种类及其作用,综述了食用菌不同部位、不同发育阶段等自身因素,及温度、金属离子、采后保鲜技术等外界环境因素对抗氧化酶活性的影响,并对食用菌抗氧化酶研究前景进行展望。     

紫外辐射对水生生物的影响研究进展

紫外辐射对陆生植物的生物学效应已被广泛研究,对水生生物也能产生一系列影响。本文在综述国内外紫外线在水体中渗透状况及影响因素的基础上,阐述了紫外辐射对浮游细菌和微型浮游生物、浮游植物、浮游动物、大型藻类、鱼卵和幼鱼、鱼类及两栖动物的生物学效应,从直接效应和间接效应两方面介绍了紫外辐射对水生生物作用的机理。未来研究应该注重紫外辐射与气候变化、酸沉降、水污染等环境因子联合作用对水生有机体产生影响,其研究对象应扩展至沉水植物、底栖生物等大部分水生有机体,这些研究将对深入研究水生生态系统的演化、水生生态系统退化及其修复起重要作用。     

酸雨对水生生物影响的研究

环境生物学家目前面临的任务之一是就酸雨对水体和水生生物的冲击作出预测。本文主要介绍酸雨分布最广、危害严重的地区,并对水生生物的影响作出分析。研究表明一个湖泊及其流域中和酸雨所进入的酸的容量,主要取决于汇水区基岩的组成。湖、河酸化所带来的最明显的生物学冲击是鱼类种群的消失或减少。而食物网中各个营养级的生物也可能受到影响。生物的数量和种类会减少,结果随着整个水生态系统的破坏,水体的初级生产力和分解作用受到伤害。 我们所进行的研究表明:鲢、餹、鲤对酸的相对敏感性是受精卵>鱼苗>鱼种;鲢鱼的96小时LC_(50)分别是pH5.34,4.51及3.80。酸雨对大型溞的急性毒性,24小时LC_(50)是pH4.06±0.19;48小时LC_(50)是pH4.94±0.20。椭园萝卜螺对酸的96小时累积死亡率分别是:pH3.6时100％,pH3.8时60％,pH4.0时20％以及pH4.2时10％。 作者对今后需要进行的研究课题提出了建议。     

生物胺降解酶研究进展及其应用

生物胺是存在于发酵食品和酒精饮料中的潜在胺类危害物。如果人体摄入过量的生物胺,则会引起呼吸困难、呕吐和发烧等过敏反应。生物胺降解酶是通过将生物胺氧化成醛类物质来实现降解生物胺的一类酶。目前发现的具有降解生物胺能力的酶主要包括胺氧化酶、胺脱氢酶和多铜氧化酶。本文详细阐述了这3类主要生物胺降解酶的催化机理、底物特异性、酶学性质、应用特性和它们对生物胺的降解效果,归纳和总结了生物胺降解酶的异源表达和分子改造的研究进展,并对生物胺降解酶在基因挖掘、分子改造和表达等方面的研究趋势进行了展望,以期为研究和开发食品中生物胺的酶法降解策略提供参考。     

水生生物粒径谱/生物量谱研究进展

介绍了水生生物粒径谱概念,粒径谱理论的提出背景及其发展历程。综述了浮游生物、底栖生物、微型生物和鱼类粒径谱的研究现状;并以粒径谱理论在鱼类潜在产量估算方面的应用为重点,介绍了粒径谱理论的应用。回顾了国内生物粒径谱研究现状;结合新陈代谢理论、宏生态学与粒径谱理论的联系,新的粒径测量手段的应用,传统分类方法与粒径方法的关系,以及粒径谱模型研究的特点,展望未来粒径谱研究的前景。认为粒径谱研究已经历了半个多世纪的发展和多个领域的应用,给人们以区别于传统物种分类的崭新视角,成为生态学研究,尤其是水生生态学研究的热点。目前水生生物包括浮游生物、底栖生物、微型生物和鱼类粒径谱/生物量谱的分析方法、模型和理论研究已取得了一些进展,但由于各类生物个体形态、结构呈现多样化,数据获取的难度以及其他各种因素影响,使得研究工作发展缓慢,海洋生物粒径谱研究尤其困难。随着海洋生物资源评估、利用与渔业生态系统管理的需要,应重视加强粒径谱/生物量谱的研究,包括不同类型生物的粒径分布曲线、捕食与被捕食之间的关系、新陈代谢特征、时空尺度变异、粒径谱模型的假设条件和新模型的建立,以及先进测量技术应用等,这将是今后粒径谱/生物量谱研究需要引起关注的重点内容。     

余氯对水生生物的影响

氯是滨河、滨海企业冷却水常用的防治污损生物的处理剂。总结近年来国内外氯在企业冷却水中的应用、氯对浮游植物、浮游动物、贝类、鱼类等影响的研究成果,为制定冷却水余氯排放标准和水产养殖的合理布局提供了参考,针对我国大量滨海电厂即将建立的现状,分析了余氯研究在中国海域研究的不足,提出了氯对我国海洋生物影响不同层面的研究方向。认为氯对生物种群的毒性,氯对生物群落组成、结构和生态演替的影响,以及减轻或避免余氯污染的对策是需要进一步解决的科学问题。     

急性低氧对大鼠微血管反应性及抗氧化酶的影响

目的：探讨不同急性低氧条件下对肠系膜微动脉血管反应性和抗氧化酶的影响。方法：实验采用给予大鼠吸入含氧量为12．5％和8．5％的氮氧混合气体,观察急性低氧后肠系膜微动脉血管口径、血流速度和血中谷光甘肽过氧化物酶（GSH—PX）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和活性氧（ROS）含量的变化。结果：肠系膜微动脉血管口径随急性低氧时间延长而逐渐增大,而血液流速却减慢（P〈0．01,P〈0．05）;SOD、CAT和GSH—PX活力明显下降,ROS含量增加（P〈0.01,P〈0．05）。结论：急性低氧可使肠系膜微动脉管径变大和血液流速减慢;同时体内抗氧化酶活性减弱,这可能与自由基产生增加有关。     

纳米酶的抗菌作用及其机制研究进展

抗生素类药物的发现和使用给人类提供了抗击细菌感染的强大武器。但是,抗生素长期使用导致的细菌耐药问题限制了其在临床上的应用。开发新型的基于纳米酶(Nano-Enzyme)的新型抗菌剂为解决上述问题提供了新思路。将纳米酶可以归为两大类:一类是酶和纳米材料的复合材料;另一类是纳米材料本身具有类酶活性。因为银(Ag)纳米粒子是历史最悠久且研究最广泛的纳米抗菌剂,而且其抗菌机制多样化,因此将Ag纳米粒子的抗菌机制和最新进展单独论述。纳米抗菌剂可以组合多种抗菌机制协同抗菌,从而提高其抗菌性能。因此,在这篇综述中系统介绍了Ag纳米粒子和上述2种类型纳米抗菌剂的最新研究进展和抗菌机制,重点介绍了纳米材料的物理性质对抗菌活性和生物安全性的影响。最后,该综述还强调了该领域目前面临的问题和挑战,并对该领域的发展前景进行了展望。     

外源SNP对干旱胁迫下不同马铃薯品种叶片抗氧化酶活性的影响

以正常水分状态、轻度干旱胁迫、中度干旱胁迫和重度干旱胁迫下的马铃薯抗旱品种‘底西瑞’和干旱敏感品种‘大西洋’ 植株为材料,于现蕾期采用0（对照）和0.01 mmol·L^-1 SNP分别喷施各处理植株,对不同处理下2个品种的植株形态、叶片超氧阴离子和H₂O₂含量以及抗氧化酶活性进行比较分析,探讨外源SNP对干旱状态下马铃薯的生理应答机制,为马铃薯的抗旱栽培提供新的技术理论支持。结果显示：（1）SNP喷施对重度水分胁迫下马铃薯植株的正常生长具有一定的保护作用。（2）在干旱胁迫条件下,马铃薯叶片POD活性在品种‘底西瑞’中增加而在品种‘大西洋’中降低,超氧阴离子含量和H₂O₂含量以及CAT和APX活性在各品种中均增加,但超氧阴离子含量和H₂O₂含量增加程度与胁迫程度无关。（3）抗旱品种‘底西瑞’在干旱胁迫下的超氧阴离子含量低于干旱敏感品种‘大西洋’,而其POD、CAT和APX活性则高于‘大西洋’; 0.01 mmol·L^-1SNP处理未改变马铃薯叶片中超氧阴离子和H₂O₂含量随土壤水分的变化趋势,但改变了‘大西洋’叶片中SOD、POD、CAT活性以及‘底西瑞’叶片中APX活性的变化趋势。（4）外源喷施0.01 mmol·L^-1SNP降低了‘底西瑞’在中度和重度胁迫下以及‘大西洋’在轻度和中度胁迫下超氧阴离子含量,提高了干旱胁迫下‘底西瑞’和‘大西洋’的POD和APX活性。研究表明,POD、CAT和APX可作为马铃薯水分胁迫下的应答以及品种抗旱性的筛选指标,外源SNP可通过诱导增强干旱胁迫下马铃薯的抗氧化酶活性来提高其抗旱性。     

Sediment-Associated Phototoxicity to Aquatic Organisms

Phototoxicity is a two to greater than 1000-fold increase in chemical toxicity caused by ultraviolet radiation (UV), which has been demonstrated in a broad range of marine and freshwater fish, invertebrates, and other aquatic organisms in water column exposures. Field collected sediments containing polycyclic aromatic hydrocarbons (PAHs) and other contaminants are phototoxic to sediment-dwelling organisms in laboratory tests, but in situ or field investigations of phototoxicity have not been reported. Sediment provides a pathway for the bioaccumulation of phototoxic chemicals through contact with and ingestion of bedded and suspended sediment, and maternal transfer, but risks are uncertain. Risks from sediment-associated phototoxicity will be greatest in areas of both high contaminant exposure (e.g., surficial and suspended sediments in harbors, outfall areas, and spill sites), and high UV exposure (e.g., high optical clarity or shallow depths). Organisms and life-stages most at risk will be those translucent to UV that inhabit the photic zone and near shore areas, but benthic organisms may have generally low UV exposure because of life history and morphological characteristics. Site-specific assessments are needed to characterize risks both spatially and temporally because of heterogeneous sediment contamination and large differences in species sensitivity and exposure pathways.     

Superoxide Production and Antioxidant Enzymes in Ammonia Intoxication in Rats

Injection of large doses of ammonium salts lead to the rapid death of animals. However, the molecular mechanisms involved in ammonia toxicity remain to be clarified. We have tested the effect of injecting 7 mmol/kg of ammonium acetate on the production of superoxide and on the activities of some antioxidant enzymes in rat liver, brain, erythrocytes and plasma. Glutathione peroxidase, superoxide dismutase and catalase activities were decreased in liver and brain (both in cytoso-lic and mitochondrial fractions) and also in blood red cells, while glutathione reductase activity remained unchanged. Superoxide production in submitochon-drial particles from liver and brain was increased by more than 100% in both tissues. Both diminished activity of antioxidant enzymes and increased superoxide radical production could lead to oxidative stress and cell damage, which could be involved in the mechanism of acute ammonia toxicity.     

The activity of recombinant human neuroglobin as an antioxidant and free radical scavenger

Free radicals are by-products of metabolism and exist in a homeostasis between generation and scavenging in vivo. Excessive free radicals cause various diseases, including nervous system diseases. Neuroglobin (Ngb), a nervous system-specific oxygen-binding protein, has been suggested to be a potential free radical scavenger in the nervous system in vivo; however, its underlying mechanism remains unclear. In this study, we investigated the antioxidant potential and free radical scavenging properties of recombinant human Ngb (rhNgb) in vitro. Interestingly, we found that the rhNgb protein itself has a direct and distinct antioxidant capacity and can efficiently scavenge a variety of free radicals, including the [2,2'-azino-di-(3-ethyl-benzthiazoline-6-sulfonic acid)] (ABTS) cation, superoxide anion, hydrogen peroxide, and hydroxyl radical. The capacity of rhNgb to scavenge the superoxide anion and hydrogen peroxide was even comparable to that of vitamin C. In addition, rhNgb had Fe(2+) chelating activity but hemoglobin did not. In conclusion, our results indicated that the rhNgb protein itself has antioxidant and free radical scavenging activities, providing fundamental evidence for the neuroprotective function of Ngb. These data provide key information for the origin of the neuroprotective and physiological role of Ngb and will promote the treatment of reactive oxygen species (ROS)-related diseases using this novel oxygen-binding globin.     

Effect of stationary magnetic field strengths of 150 and 200 mT on reactive oxygen species production in soybean

Our previous investigation reported the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean. In this study, soybean seeds treated with static magnetic fields of 150 and 200 mT for 1 h were evaluated for reactive oxygen species (ROS) and activity of antioxidant enzymes. Superoxide and hydroxyl radicals were measured in embryos and hypocotyls of germinating seeds by electron paramagnetic resonance spectroscopy and kinetics of superoxide production; hydrogen peroxide and antioxidant activities were estimated spectrophotometrically. Magnetic field treatment resulted in enhanced production of ROS mediated by cell wall peroxidase while ascorbic acid content, superoxide dismutase and ascorbate peroxidase activity decreased in the hypocotyl of germinating seeds. An increase in the cytosolic peroxidase activity indicated that this antioxidant enzyme had a vital role in scavenging the increased H(2)O(2) produced in seedlings from the magnetically treated seeds. Hence, these studies contribute to our first report on the biochemical basis of enhanced germination and seedling growth in magnetically treated seeds of soybean in relation to increased production of ROS.     

Modulation of Glutathione and Glutathione Dependent Antioxidant Enzymes in Mouse Heart Following Doxorubicin Therapy

The toxicity of the antineoplastic agent doxorubicin (DOX) has been shown to be moderated by the antioxidant enzyme glutathione peroxidase. It has been reported that acute doses of DOX can cause an inhibition of glutathione peroxidase in cardiac tissue, that may render this tissue especially susceptible to further prooxidant damage. In this study, multiple DOX treatments at a therapeutic dose were assessed for their effect on the antioxidant enzyme status of cardiac and kidney tissue. DOX was administered i.p. (5 mg/kg) once a week for two weeks to male balb/c mice. The activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX) and glutathione reductase (GR) were measured 1, 2 and 7 days following the second DOX treatment in both heart and kidney. Levels of reduced glutathione (GSH) were also measured in cardiac tissue at these same times. Cardiac levels of GPOX and GR showed a time-dependent decrease in activity, with 10% and 12% inhibition for GPOX and GR, respectively, at 7 days post second treatment. Cardiac levels of GSH also showed a significant decrease, approximately 15%, at 7 days post second treatment. Cardiac levels of SOD and CAT as well as kidney levels of all four antioxidant enzymes were not affected by DOX treatment. These data suggest that DOX given in a therapeutic regimen, at a therapeutic dose, can cause decreases in cardiac levels of GPOX, GR and GSH that could render the heart especially susceptible to further oxidative challenge.     

Copper-induced oxidative stress and antioxidant defence in Arabidopsis thaliana

Content of reactive oxygen species (ROS): O2*-, H2O2 and OH* as well as activities of antioxidant enzymes: superoxide dismutase (SOD), guaiacol peroxidase (POX) and catalase (CAT) were studied in leaves of Arabidopsis thaliana ecotype Columbia, treated with Cu excess (0, 5, 25, 30, 50, 75, 100, 150 and 300 microM). After 7 days of Cu action ROS content and the activity of SOD and POX increased, while CAT activity decreased in comparison with control. Activities of SOD, POX and CAT were correlated both with Cu concentration (0-75 microM) in the growth medium and with OH* content in leaves. Close correlation was also found between OH* content and Cu concentration. Oxidative stress in A. thaliana under Cu treatment expressed in elevated content of O2*-, H2O2 and OH* in leaves. To overcome it very active the dismutase- and peroxidase-related (and not catalase-related, as in other plants) ROS scavenging system operated in A. thaliana. Visual symptoms of phytotoxicity: chlorosis, necrosis and violet colouring of leaves as well as a reduction of shoot biomass occurred in plants.     

环境污染物对水生生物产生氧化压力的分子生物标志物

为了能够建立一种简单、快速、准确的环境污染监测预警体系,人们进行了广泛的研究,其中有关环境污染物对分子生物标志物的影响已成为研究热点。生物体内的氧自由基和其它活性氧分子（ROS）对组织和细胞成分造成的伤害,称之为氧化压力,环境中的有毒物质能够对生物体产生不同程度的氧化压力。生物体内的强氧化剂或体外因素（如环境污染物）引起的强氧化物与抗氧化防御系统之间的平衡能够用于评估环境压力对生物体产生影响的程度,尤其适合于评估不同种化学物质引起氧化损伤的程度。这些抗氧化防御系统及其对氧化压力的敏感性在环境毒物学研究中占有非常重要的地位,大量研究结果表明：过渡金属、多环芳烃、有机氯和有机磷农药、多氯联苯、二氧芑和其它异型物质都能够对生物体产生氧化压力。这些有毒物质能够引起各种有害影响,如对膜脂、DNA和蛋白产生损伤;改变抗氧化酶的活性等。总结了这种氧化压力的研究进展情况,并讨论了这些分子生物标志物在水生生物中的应用。     

外源NO对南方红豆杉幼苗光合色素及抗氧化酶的影响

以4年生南方红豆杉幼苗为实验材料,通过对南方红豆杉幼苗喷施不同浓度外源一氧化氮（NO）供体硝普钠溶液（0、0.01、0.1、0.5和1 mmol·L^-1SNP）,测定光合色素含量、抗氧化酶活性、丙二醛（MDA）含量和过氧化氢（H₂O₂）含量等生理指标,以探讨不同浓度外源NO对南方红豆杉叶片光合色素和抗氧化酶的影响。结果表明：喷施低浓度（0.01、0.1 mmol·L^-1）SNP可显著提高南方红豆杉叶片的叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量,增加叶绿素a/b的比值,而喷施高浓度（0.5、1 mmol·L^-1）SNP降低了叶片的光合色素含量。随着外源NO供体浓度的增加,叶片过氧化氢酶(CAT)活性显著增加,过氧化物酶(POD)活性先增加后降低。此外,处理前期,低浓度SNP处理明显提高了抗坏血酸过氧化物酶(APX)活性,而高浓度SNP处理显著降低了APX活性,处理后期APX活性随SNP浓度的增加而显著下降。喷施低浓度SNP可有效提高超氧化物歧化酶(SOD)活性和增加可溶性蛋白含量,降低MDA和H₂O₂的含量,而喷施高浓度SNP显著增加了MDA和H₂O₂的含量。因此,低浓度的SNP（<0.5 mmol·L^-1）处理南方红豆杉幼苗,可增加其叶绿素含量,提高抗氧化酶活性,降低MDA和H₂O₂的含量,而高浓度的SNP（≥0.5 mmol·L^-1）处理会降低叶绿素含量,提高H₂O₂含量,增加细胞膜质过氧化程度,从而对南方红豆杉幼苗造成一定伤害。