植物光毒素作用机理

光激发植物光毒素产生单线态氧或自由基,破坏核酸、脂质和蛋白质等,对病毒、细菌、真菌、线虫、昆虫和其他植物产生毒性,在植物的防护反应中具有重要作用．     

昆虫资源利用及其产业化进展

主要从食用昆虫、饲用昆虫、药用昆虫、工业原料昆虫、传粉昆虫、观赏娱乐昆虫、天敌昆虫、环保昆虫以及昆虫生物反应器和昆虫在仿生学上的应用等方面全面综述了昆虫资源的利用及其产业化进展.     

基于服务功能的昆虫生态调控理论

鉴于昆虫在植物传粉授精、害虫生物控制、土壤有机物分解中提供多种生态系统服务功能,本文在害虫生态调控、区域性害虫生态调控与生境管理的基础上,进一步提出基于多种生态服务功能的农田景观昆虫生态调控理论、方法与实践。认为:昆虫管理不仅仅是害虫的管理,还应包括有益昆虫(如传粉昆虫、天敌昆虫、分解昆虫)的管理,这种管理应从单一农田生态系统扩展到农田景观生态系统,充分考虑农田景观中昆虫的传粉功能、生物控害功能和分解功能,通过对功能植物、作物与非作物生境的空间布局以及时间序列上的生态设计,从空间上明确昆虫(包括害虫、天敌、传粉昆虫、分解昆虫)在不同生境中的转移扩散动态,从时间上掌握昆虫在不同寄主植物与非作物生境上的演替过程,从技术上着重发挥有利于昆虫的传粉功能、生物控害功能和分解功能的综合措施,在研究方法上突出使用稳定同位素、生态能量学、化学生态学等定量分析手段,研究景观区域内中"植物-昆虫"互作过程及其生态调控措施的作用,寻求不同时空条件下控害保益的关键措施,设计和组装出维持多功能的农田景观昆虫生态调控技术体系,创造有利于天敌控害、蜜蜂传粉、土壤分解的环境条件,以发挥昆虫类群在农田景观中最大的生态服务功能。     

脂质组学研究方法及其应用

脂质不仅是生物膜的骨架成分和能量贮存物质, 越来越多的证据表明, 脂质也参与细胞的许多重要功能。脂质组学是代谢组学的一个重要分支, 主要研究生物体内所有的脂质分子的特性以及它们在蛋白质表达和基因调控过程中的作用。脂质组学是依赖技术驱动的科学。近年来, 随着人们对脂质研究的重视, 脂质组学研究方法和策略有了突破性进展, 在动物上开发出的脂质组学分析方法已经扩展应用到植物上。该文重点介绍脂质组学的研究方法及其应用, 以期推动脂质组学,特别是植物脂质组学的进一步发展。     

脂质组学研究方法及其应用

脂质不仅是生物膜的骨架成分和能量贮存物质,越来越多的证据表明,脂质也参与细胞的许多重要功能。脂质组学是代谢组学的一个重要分支,主要研究生物体内所有的脂质分子的特性以及它们在蛋白质表达和基因调控过程中的作用。脂质组学是依赖技术驱动的科学。近年来,随着人们对脂质研究的重视,脂质组学研究方法和策略有了突破性进展,在动物上开发出的脂质组学分析方法已经扩展应用到植物上。该文重点介绍脂质组学的研究方法及其应用,以期推动脂质组学,特别是植物脂质组学的进一步发展。     

封面照片:访花昆虫短毛斑金龟Lasiotrichius succinctus(Pallas)

访花昆虫主要指在显花植物上活动较为频繁的昆虫种类,包括传粉昆虫、天敌昆虫以及取食花朵的昆虫。     

昆虫的RNA干扰

RNA干扰(RNAi)是一种强有力的分子生物学技术, 在昆虫研究中得到了较多的应用。目前, RNAi技术主要应用于昆虫功能基因和功能基因组研究, 已在多个目的19种昆虫上实现了RNAi。在昆虫上实现RNAi的方法主要有注射、浸泡、喂食、转基因和病毒介导等方法, 这些方法各有特点, 其中喂食法因其简单而最有应用前景。昆虫RNAi的系统性较为复杂, 只有部分昆虫具有RNAi的系统性。昆虫中RNAi信号传导的基因可能是sid-1, 但昆虫RNAi的系统性机理还不是很清楚。转基因植物产生的dsRNA实现了对作物的保护, 证实了RNAi技术可用于害虫控制, 为害虫控制开辟了新领域。昆虫的RNAi研究处在起步阶段, 研究昆虫RNAi的机理, 特别是RNAi在昆虫体内的系统性扩散机理, 改进实现RNAi的方法, 提高RNAi技术在昆虫研究中的应用, 有利于昆虫基因功能鉴定和害虫控制, 促进昆虫学科的发展。     

昆虫行为的左右非对称性研究进展

大脑和行为的左右非对称性一直以来被认为是人类特有的,现在广泛存在于脊椎动物中,而近期又发现无脊椎动物中也存在行为偏侧性。近年来大量研究表明,群居型昆虫的嗅觉行为和大脑的非对称性表现在种群水平上,少数散居型昆虫行为的非对称性往往表现在个体水平上。当前,昆虫行为的单侧性是一个重要的研究领域,有助于对生物多样性中单侧性的早期起源有一个更深刻的认识,对探索昆虫进化发展具有重要的科学意义。对大多数昆虫而言,行为的偏侧性都是通过对触角的左右非对称性研究来实现的,触角作为昆虫感觉系统的重要组成部分,在昆虫寄主定位、识别、取食、觅偶、交配、繁殖、栖息、防御与迁移、稳定飞行速率等社会性行为过程中起着极为重要的作用。本文回顾了国内外膜翅目、双翅目、半翅目、蜚蠊目和直翅目昆虫行为非对称性研究的最新进展,有助于分析不同种类昆虫在进化历史上的相似性以及探讨昆虫在个体水平和群体水平上的进化差异。     

有机稻田埂植物上节肢动物多样性

对稻鸭共作有机稻和常规稻田埂杂草、大豆和芝麻上的节肢动物群落进行了全季节系统调查,共采集2纲、12目、76科、172种,其中天敌103种(包括33种蜘蛛,6种捕食性昆虫和64种寄生性昆虫)、植食性昆虫64种.结果表明,蜘蛛和天敌昆虫丰富度以有机稻田埂最大,其蜘蛛物种数和个体数是常规田埂的4.5倍以上,天敌昆虫物种数和个体数是常规田埂的1.5倍以上.比较田埂植物上昆虫多样性表明,在有机稻田,大豆和杂草田埂上的昆虫物种丰富度最大(71),其次是芝麻(62),而杂草上的Shannon多样性指数最大;在常规稻田,大豆田埂上昆虫丰富度(52)和Shannon多样性指数最大,杂草上的昆虫Shannon多样性指数最小.有机田埂杂草上蜘蛛和飞虱发生动态有明显的跟随现象,由于喷施杀虫剂防治飞虱,常规田埂杂草上的蜘蛛和飞虱数量都处于较低水平,且没有明显的跟随现象.调查结果说明,有机稻田比常规稻田更有利于天敌的保护,在常规管理模式下田埂种植大豆和芝麻对稻田节肢动物群落保护具有积极作用.     

昆虫教学标本的采集及制备

昆虫标本是昆虫种类的物证。在昆虫教学中使用实物标本,可使学生加深记忆和理解程度。昆虫种类千万,生活习性各异,要得到教学上需要的一套完整标本,必须掌握正确的采集和制作方法。     

Nonbilayer lipids affect peripheral and integral membrane proteins via changes in the lateral pressure profile

Nonbilayer lipids can be defined as cone-shaped lipids with a preference for nonbilayer structures with a negative curvature, such as the hexagonal phase. All membranes contain these lipids in large amounts. Yet, the lipids in biological membranes are organized in a bilayer. This leads to the question: what is the physiological role of nonbilayer lipids? Different models are discussed in this review, with a focus on the lateral pressure profile within the membrane. Based on this lateral pressure model, predictions can be made for the effect of nonbilayer lipids on peripheral and integral membrane proteins. Recent data on the catalytic domain of Leader Peptidase and the potassium channel KcsA are discussed in relation to these predictions and in relation to the different models on the function of nonbilayer lipids. The data suggest a general mechanism for the interaction between nonbilayer lipids and membrane proteins via the membrane lateral pressure.     

Multiple bonds for the lipid interest

Polyene lipids and alkyne lipids allow study of lipid organization, dynamics and metabolism. Both types of lipids contain multiple bonds as the essential functional group, leading to minimal disturbance of the hydrophobic properties on which the characteristic behavior of lipids is based. Polyene lipids can directly be traced due to their intrinsic fluorescence, while alkyne lipids need the copper-catalyzed click reaction to an azido-reporter for detection. This review describes recent developments in synthesis and application of both types of lipid analogs with emphasis on metabolic tracing and microscopy imaging. This article is part of a Special Issue entitled Tools to study lipid functions.     

Studies on mixed monolayers of phospholipids and fusogenic lipids.

1. The behaviour of mixed monolayers of 14 different lipids with preparations of erythrocyte lipids, purified natural and synthetic phospholipids, cholesterol and galactosylceramide was investigated. 2. The mean areas occupied per molecule in mixed films containing lipids that are fusogenic for hen erythrocytes were compared with those for corresponding films containing lipids that are inactive as fusogens. 3. Fusogenic lipids were found to exhibit interactions, which were not shown by non-fusogenic lipids, in mixed monolayers with several species of phospholipid, particularly those containing a choline head group. 4. Heterogeneity in the hydrophobic chains of phosphatidylcholine, their degree of unsaturation and the presence of cholesterol had little effect on the interaction of phosphatidylcholine with fusogenic lipids. 5. Fusogenic lipids showed little specific interaction with natural or synthetic preparations of phosphatidylethanolamine. 6. The possible significance of these observations in relation to the action of fusogenic lipids on biological membranes is discussed in the light of the asymmetrical distribution of phospholipids in erythrocyte membranes.     

Formation of lipid reserves in fat body and eggs of the yellow fever mosquito, Aedes aegypti

We examined the accumulation of lipids in adult females of the mosquito, Aedes aegypti. Females emerged with about 100 μg lipid in the fat body. With access to sugar water lipids increased over seven days to 300 μg. After a blood meal on day five, sugar-fed females accumulated 120-140 μg of lipids in their ovaries within 2 days. At the same time the lipid content of the fat body decreased by 100 μg, indicating transfer of lipids from fat body to oocytes. Experiments in which fat body lipids were prelabelled support this conclusion. Label was transferred to oocytes: in mature oocytes the specific radioactivity of lipids was 80% of the specific radioactivity of prelabeled fat body lipids. Components of blood meals are also used to synthesize oocyte lipids. Fat bodies of females starved for four days had only 27 μg of lipids left. When these females were given a blood meal, they matured oocytes, although the number of ooyctes was reduced and ovaries contained only half the amount of lipids found in ovaries of females which had first fed on sugar water. Fat body lipids of these females had only slightly increased to 36 μg. This demonstrates that female Ae. aegypti use sugar to synthesize lipids, but they can also use components of blood for this purpose.     

Kinetic characteristics of lipids of mammalian tissues in autooxidation reactions

We generalize the results of multiyear studies of the level of antioxidative activity of lipids isolated from tissues of laboratory rodents of different species and lines. A classification of lipids according to their ability to inhibit thermal autooxidation of methyl oleate is proposed. The involvement of lipids in low-temperature autooxidation reactions at the radical initiation and chain propagation stages was proved using the model developed. In addition to antioxidative activity, the initial content of peroxides in lipids, determined by their degree of unsaturation, and the antiperoxide activity of lipids are proposed for quantitative estimation of the kinetic characteristics of lipids of mammalian tissues. The dependence of effects on the rate of radical initiation in the system is shown, which is determined by the influence of the physicochemical properties of lipids on the coordination of relationships and balance of biochemical functions in biological objects differing in the intensity of oxidation processes.     

Evidence for specificity in lipid-rhodopsin interactions

The interaction of bovine rhodopsin with poly- and monounsaturated lipids was studied by (1)H MAS NMR with magnetization transfer from rhodopsin to lipid. Experiments were conducted on bovine rod outer segment (ROS) disks and on recombinant membranes containing lipids with polyunsaturated, docosahexaenoyl (DHA) chains. Poly- and monounsaturated lipids interact specifically with different sites on the rhodopsin surface. Rates of magnetization transfer from protein to DHA are lipid headgroup-dependent and increased in the sequence PC < PS < PE. Boundary lipids are in fast exchange with the lipid matrix on a time scale of milliseconds or shorter. All rhodopsin photointermediates transferred magnetization preferentially to DHA-containing lipids, but highest rates were observed for Meta-III rhodopsin. The experiments show clearly that the surface of rhodopsin has sites for specific interaction with lipids. Current theories of lipid-protein interaction do not account for such surface heterogeneity.     

Developmental differences in activation of cholinephosphate cytidylyltransferase by lipids in rabbit lung cytosol

Lung cytosolic cholinephosphate cytidylyltransferase is activated by lipids. We examined the lipid activation pattern as a function of development in rabbit lung from 27 days gestation through term (31 days) and in the adult. The enzyme in both the fetal and adult cytosol was dependent on lipids for activity. Extraction of the cytosol with acetone/butanol virtually abolished cytidylyltransferase activity, but the activity could be restored on addition of lipids extracted with chloroform/methanol from additional cytosol. Cytosolic phospholipids from the fetal lung reactivated cytidylyltransferase but both neutral lipids and phospholipids from the adult were required. The lipids had the same effect on cytidylyltransferase activity in delipidated cytosol from either the fetus or adult so the difference in activation pattern was attributable to the lipids rather than the protein. There was a shift from the fetal to the adult lipid activation pattern as development progressed. Further, there was a significant correlation between cytidylyltransferase activities in intact cytosols from developing lung and activities in delipidated cytosol in the presence of lipids from the same animals. Although these data suggest that lipids regulate cytosolic cytidylyltransferase activity in developing lung their physiological significance remains to be established.     

A lipid-phase separation model of low-temperature damage to biological membranes

An hypothesis is proposed to explain the damage caused to biological membranes exposed to low temperatures. The thesis rests on the general observation that the lipid components of most membranes are heterogeneous and undergo phase transitions from gel-phase lamellae to liquid-crystalline lamellae and some to a non-lamellar, hexagonal-II phase over a wide range of temperatures. As a consequence of these phase transitions the lateral distribution of the lipids characteristic of the growth temperature is disturbed and redistribution takes place on the basis of the temperature at which phase transitions occur. When membranes are cooled, first the non-lamellar forming lipids pass through a transition to a fluid lamellar phase and are miscible with bilayer-forming lipids into which they diffuse. On further cooling the high-melting-point lipids begin to crystallize and separate into a lamellar gel phase, in the process excluding the low-melting point lipids and intrinsic proteins. The lipids in these remaining regions form a gel phase at the lowest temperature. It is suggested that, because the non-lamellar lipids tend to undergo a liquid-crystalline to gel-phase transition at higher temperatures than lamellar-forming lipids, these will tend to phase separate into a gel phase domain rich in these lipids. Damage results when the membrane is reheated, whereupon the hexagonal-II-forming lipids give rise to non-lamellar structures. These probably take the form of inverted micelles sandwiched within the lipid bilayer and they completely destroy the permeability barrier properties of the membrane. The model is consistent with the phase behavior of membrane lipids and the action of cryoprotective agents in modifying lipid phase properties.     

Very Long-Chain Fatty Acids in Composition of Plant Membrane Lipids

Literary data on very long-chain fatty acids (VLCFAs) that are present in polar lipids of the plant cell membranes are discussed. Large amounts of VLCFA are found in polar lipids of some cellular organelles as well as in nonextractable lipids from diverse plant objects, where the influence of surface lipids on the relative content of these FAs is excluded. In some plants, the VLCFA fraction in membrane lipids increases under several kinds of stress. Amounts and diversity of VLCFAs are lower in flowering plants as compared with the representatives of more ancient taxons—gymnosperms, ferns, and marine algae. Presence of VLCFAs in the composition of annular lipids of the cell membranes is assumed. Biosynthesis of VLCFAs, enzymes involved in the process, and encoding genes are discussed.     

General model for lipid-mediated two-dimensional array formation of membrane proteins: application to bacteriorhodopsin.

Based on experimental evidence for 2D array formation of bacteriorhodopsin, we propose a general model for lipid-mediated 2D array formation of membrane proteins in lipid bilayers. The model includes two different lipid species, "annular" lipids and "neutral" lipids, and one protein species. The central assumption of the model is that the annular lipids interact more strongly with the protein than with the neutral lipids. Monte Carlo simulations performed on this model show that 2D arrays of proteins only form when there are annular lipids present. In addition, no arrays form if all of the lipids present are annular lipids. The geometry of the observed arrays is for the most part hexagonal. However, for a certain range of low annular lipid/protein ratios, arrays form that have geometries other than hexagonal. Using the assumption that the hydrocarbon chains of the annular lipids are restricted in motion when close to a protein, we expand the model to include a ground state and an excited state of the annular lipids. The main result from the extended model is that within a certain temperature range, increasing the temperature will lead to larger and more regular protein arrays.