c-fos蛋白在白蚁婚飞时脑中免疫组织化学定位观察(简报)

在原癌基因家族中有一类可以被第二信使诱导的原癌基因,它们能对神经递质、激素等刺激作出反应进行表达,这类基因称为即刻早基因(imme- diate-early gene,IEG)。c-fos就是其中重要的一种即刻早基因。目前已经证实哺乳动物的性行为与其脑中的c-fos表达有关,c-fos特异性表达被认为是研究性行为时脑部神经细胞活动的重要指征,Joppa 等人用此方法已经在鼠、仓鼠脑中定位出与性行为有关的神经活动区域。c-fos在昆虫的脑中也有表达,但有关昆虫性行为时的脑部神经细胞c-fos表达未见有报道。婚飞是白蚁重要的性行为,婚飞行为是否像哺乳动物那样与脑部神经细胞c-fos表达有关呢?因此本文研究的目的是:(1)用免疫细胞化学方法检测雌、雄繁殖蚁婚飞时脑中是否有c-fos特异性表达。(2)研究c-fos在白蚁脑中的精确定位,了解与其性行为有关的脑部神经活动区域。(3)为进一步推测c-fos在白蚁婚飞中可能的作用及婚飞的分子调节机制提供依据。     

双翅目昆虫传粉研究进展

昆虫传粉不仅在自然生态系统中发挥着十分重要的作用,也和农业生态系统中产量密切相关。众所周知,膜翅目昆虫是最重要的传粉昆虫。双翅目昆虫分布广,物种多,数量大,也是一类十分重要的传粉昆虫,但其传粉作用未受到足够的重视。本文主要综述了双翅目传粉昆虫的主要种类、传粉效力、传粉特征、与植物的协同进化以及双翅目昆虫传粉的生态学意义。据记载双翅目昆虫中至少有71个科涉及虫媒种类,目前有资料显示访花昆虫类群中双翅目约有54 417种,按涉及的种数排序居于昆虫纲传粉昆虫目中第4位。尽管双翅目昆虫单次访问可携带花粉量相对较少(相比于膜翅目),但是较高访问速率及庞大的个体数量,保证了其作为有效传粉者的地位。传粉综合征能够有效揭示植物与传粉者的协同进化关系,尤其是对一些专化传粉现象(如五味子科-瘿蚊系统)和泛化传粉的深入研究,更加深了我们对协同进化的理解。就生态学意义而言,一方面双翅目传粉昆虫是膜翅目传粉昆虫的有益补充,另一方面在一些特殊环境中,双翅目昆虫具有不可替代的作用。当前传粉昆虫(包括双翅目)数量急剧下降,而且双翅目昆虫的传粉价值还利用较少。结合我国当前的研究现状提出了以下未来研究重点:1)加深双翅目传粉效力和适应意义的案例研究以明确双翅目昆虫在传粉体系中的地位;2)加强栖息地格局变化与昆虫多样性的研究以明确栖息地改变对昆虫的影响程度;3)梳理访花和传粉、专化传粉和泛化传粉等关系以更加明确双翅目昆虫在与植物协同进化中的作用;4)逐步深入探讨花粉浪费和花粉竞争以探究传粉策略和植物繁殖策略。这些努力将为双翅目传粉昆虫的知识普及、资源保护与利用研究等方面提供参考。     

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。     

第一届国际双翅目学会议简介

第一届国际双翅目学会议(First International Congress of Dipterology)于1986年8月17—24日在布达佩斯召开,大会学术报告有二:加拿大G.C.D.Griffiths博士讲了“双翅目内的大群分类评述”,捷克M,Chvala博士讲了“双翅目的婚飞是有效的行为隔离机制。” 参加会议的正式成员248人,来自35个国家或地区,出席人数最多为匈牙利(44人)、顺次为美国、捷克、西德、英国、苏联、波兰、加拿大,我国有3人出席。大会通过下列决议: 1.本会议对匈牙利科学院生物学部,Tibor Jermy 博土及组织委员会的所有成员给予第一届双翅目学会议的款待和有效率的组织工作表示真诚的感谢;     

鸟类的求偶行为及其生物学意义

鸟类的繁殖具有明显的季节性。每当进入繁殖季节以后 ,随着鸟类性腺的发育 ,会出现一系列的繁殖活动。其中第一步常常是通过求偶行为而形成一定的配偶关系。求偶行为是鸟类通过婉转鸣唱 ,展示华丽多彩的婚羽或色彩斑斓的冠囊、角、裙等附属物 ,进行婚飞、戏飞或其它行为姿态吸引异性的一种活动。1　求偶行为的主动性雌鸟和雄鸟由谁先出现求偶行为呢 ?谁在求偶行为中表现主动呢 ?这是由鸟类的外貌决定的。我们知道 ,多数鸟类的雌雄鸟外貌之间存在着明显的差别。一般雄鸟具有色彩艳丽的羽毛或“婚装” ,而雌鸟的羽色较为平淡。所以 ,大多数鸟…     

内蒙古阿拉善骆驼生活环境水生双翅目昆虫种类调查

【目的】通过对内蒙古阿拉善骆驼生活环境中水生双翅目昆虫的调查研究,以明确其种类的组成和分布。【方法】于2014年5-9月利用网捕法,调查了阿拉善骆驼生活环境水生双翅目昆虫。对鉴定的吸血种类的COI基因序列进行了测序和分析。【结果】共发现水生双翅目昆虫21科41属47种,其中有16种为内蒙古地区新记录,12种为吸血种类,长角亚目、芒角亚目和短角亚目个体数量分别占水生双翅目昆虫总数的49.3%,43.5%和7.2%。分子数据分析显示,12种吸血水生双翅目昆虫的COI基因序列一致性在75.9%~97.3%之间,不同科之间大部分水生双翅目昆虫差异显著,科内不同属间差异也较明显。【结论】本研究基本上掌握了内蒙古骆驼生活环境水生双翅目昆虫的种类,特别是吸血种类,为后期骆驼福斯盘尾丝虫病传播媒介种属的确定提供了基础数据。     

水生双翅目昆虫监测水体重金属污染的研究

水生双翅目昆虫是监测水体重金属污染的理想对象。文章归纳用于监测重金属污染的水生双翅目昆虫的种类,重点介绍水生双翅目昆虫在重金属污染下外部形态、内部结构、生化及分子水平的变化,以及相关生物标志物的研究,为水生双翅目昆虫用于水体重金属污染的生物监测提供科学依据。     

南京地区外来植物一年蓬上访花昆虫的多样性及其访花选择性的影响因素分析

为揭示外来植物一年蓬Erigeron annuus上的本土访花昆虫多样性和影响访花行为的因素, 本研究在南京郊区进行了连续2年的野外调查, 采用跨栏模型分析了环境因素如何影响昆虫的访花选择性, 即接受概率（测度是否接受一年蓬花）和访问频数（测度接受一年蓬花的程度）。调查发现, 访问一年蓬花的昆虫共计9目54科145种, 其中, 科丰富度占优势的是膜翅目、 鳞翅目和鞘翅目（均占总科数的20.75%）, 其次是双翅目（18.87%）和半翅目（13.21%）; 物种丰富度占优势的是双翅目（26.39%）, 其次是膜翅目（18.75%）、 半翅目（18.75%）、 鞘翅目（17.36%）和鳞翅目（15.38%）。多数目的物种丰富度在6-7月最高, 9月最低, 仅双翅目（食蚜蝇为主）在5月最高。运用跨栏模型对物种优势度最大的半翅目、 膜翅目和双翅目等的访花个体数量及其影响因素的分析结果表明： 影响半翅目和膜翅目对一年蓬花访问倾向（接受概率）的因素多于影响其访问频数的因素, 由此预测这些访花昆虫可能参考较多因素做出是否接受一年蓬花, 而依据较少线索做出访问程度的访花行为决策; 一年蓬植株密度影响半翅目和膜翅目昆虫的接受概率, 而花密度影响半翅目和双翅目昆虫的接受概率和访问频数, 说明靶标植物花的特性可能对访花昆虫的访花行为决策起主要作用。     

双翅目昆虫翅的退化

介绍了双翅目昆虫翅退化的5种主要类型,即短翅型、狭翅型、小翅型、弱翅型和无翅型;及翅退化双翅目昆虫的一些特殊生境诸如高原、海洋、地表以下之类。同时就双翅目昆虫翅退化的原因和机理进行了讨论。     

珠颈斑鸠繁殖生态初步观察

珠颈斑鸠在扬州市每年繁殖１－２次，每年在４月配对，雄鸟常发出３声，４声及两声求偶鸣叫，还要进行“婚飞”，雄鸟问雌鸟点头或鞠躬、对飞等行为。雌雄鸟营巢于树干的中层，巢的结构简单。满窠产卵两株。孵卵期１７－１８天。育雏期１９－２０天。     

Genetic Determinants of Swarming in Rhizobium etli

Swarming motility is considered to be a social phenomenon that enables groups of bacteria to move coordinately atop solid surfaces. The differentiated swarmer cell population is embedded in an extracellular slime layer, and the phenomenon has previously been linked with biofilm formation and virulence. The gram-negative nitrogen-fixing soil bacterium Rhizobium etli CNPAF512 was previously shown to display swarming behavior on soft agar plates. In a search for novel genetic determinants of swarming, a detailed analysis of the swarming behavior of 700 miniTn5 mutants of R. etli was performed. Twenty-four mutants defective in swarming or displaying abnormal swarming patterns were identified and could be divided into three groups based on their swarming pattern. Fourteen mutants were completely swarming deficient, five mutants showed an atypical swarming pattern with no completely smooth edge and local extrusions, and five mutants displayed an intermediate swarming phenotype. Sequence analysis of the targeted genes indicated that the mutants were likely affected in quorum-sensing, polysaccharide composition or export, motility, and amino acid and polyamines metabolism. Several of the identified mutants displayed a reduced symbiotic nitrogen fixation activity.     

Characterization of swarming motility in Citrobacter freundii

Bacterial swarming motility is a flagella-dependent translocation on the surface environment. It has received extensive attention as a population behavior involving numerous genes. Here, we report that Citrobacter freundii, an opportunistic pathogen, exhibits swarming movement on a solid medium surface with appropriate agar concentration. The swarming behavior of C. freundii was described in detail. Insertional mutagenesis with transposon Mini-Tn5 was carried out to discover genetic determinants related to the swarming of C. freundii. A number of swarming genes were identified, among which flhD, motA, motB, wzx, rfaL, rfaJ, rfbX, rfaG, rcsD, rcsC, gshB, fabF, dam, pgi, and rssB have been characterized previously in other species. In mutants related to lipopolysaccharide synthesis and RcsCDB signal system, a propensity to form poorly motile bacterial aggregates on the agar surface was observed. The aggregates hampered bacterial surface migration. In several mutants, the insertion sites were identified to be in the ORF of yqhC, yeeZ, CKO_03941, glgC, and ttrA, which have never been shown to be involved in swarming. Our results revealed several novel characteristics of swarming motility in C. freundii which are worthy of further study.     

Characterization of Proteus mirabilis Precocious Swarming Mutants: Identification of rsbA, Encoding a Regulator of Swarming Behavior

Proteus mirabilis swarming behavior is characterized by the development of concentric rings of growth that are formed as cyclic events of swarmer cell differentiation, swarming migration, and cellular differentiation are repeated during colony translocation across a surface. This cycle produces the bull’s-eye colony often associated with cultures of P. mirabilis. How the cells communicate with one another to coordinate these perfectly synchronized rings is presently unknown. We report here the identification of a genetic locus that, when mutated, results in a precocious swarming phenotype. These mutants are defective in the temporal control of swarming migration and start swarming ca. 60 min sooner than wild-type cells. Unlike the wild type, precocious swarming mutants are also constitutive swarmer cells and swarm on minimal agar medium. The defects were found to be localized to a 5.4-kb locus on the P. mirabilis genome encoding RsbA (regulator of swarming behavior) and the P. mirabilis homologs to RcsB and RcsC. RsbA is homologous to membrane sensor histidine kinases of the two-component family of regulatory proteins, suggesting that RsbA may function as a sensor of environmental conditions required to initiate swarming migration. Introduction of a rsbA mutation back into the wild type via allelic-exchange mutagenesis reconstructed the precocious swarming phenotype, which could be complemented in trans by a plasmid-borne copy of rsbA. Overexpression of RsbA in wild-type cells resulted in precocious swarming, suggesting that RsbA may have both positive and negative functions in regulating swarming migration. A possible model to describe the role of RsbA in swarming migration is discussed.     

Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior

Proteus mirabilis is a dimorphic bacterium which exists in liquid cultures as a 1.5- to 2.0-microns motile swimmer cell possessing 6 to 10 peritrichous flagella. When swimmer cells are placed on a surface, they differentiate by a combination of events that ultimately produce a swarmer cell. Unlike the swimmer cell, the polyploid swarmer cell is 60 to 80 microns long and possesses hundreds to thousands of surface-induced flagella. These features, combined with multicellular behavior, allow the swarmer cells to move over a surface in a process called swarming. Transposon Tn5 was used to produce P. mirabilis mutants defective in wild-type swarming motility. Two general classes of mutants were found to be defective in swarming. The first class was composed of null mutants that were completely devoid of swarming motility. The majority of nonswarming mutations were the result of defects in the synthesis of flagella or in the ability to rotate the flagella. The remaining nonswarming mutants produced flagella but were defective in surface-induced elongation. Strains in the second general class of mutants, which made up more than 65% of all defects in swarming were motile but were defective in the control and coordination of multicellular swarming. Analysis of consolidation zones produced by such crippled mutants suggested that this pleiotropic phenotype was caused by a defect in the regulation of multicellular behavior. A possible mechanism controlling the cyclic process of differentiation and dediferentiation involved in the swarming behavior of P. mirabilis is discussed.     

Zooplankton swarms: characteristics,proximal cues and proposed advantages

This review focuses on monospecific swarms of four taxonomic groups of small crustaceans: three groups are marine copepods: oithonids (Oithona and Dioithona), Acartia species and Calanus species; and the fourth group includes freshwater cladoceran species in the Order Anomopoda. For each of these groups there is a substantial literature on swarming behavior from field studies and laboratory experiments. Swarming characteristics of each taxonomic group are reviewed, proximal cues for swarming are described, comparisons are made for proposed advantages of swarming, and future research directions are suggested. Swarming characteristics of Calanus spp. are distinctly different from those of the smaller crustaceans: the oithonids, acartiids and cladocerans. In a conceptual model proposed for the smaller crustaceans, swarming behavior is affected by their interactions with light cues, water currents and turbulence, behavior of their predators and prey, and abundance of other trophic levels.     

Dynamics of Snake-like Swarming Behavior of Vibrio alginolyticus

Swarming represents a special case of bacterial behavior where motile bacteria migrate rapidly and collectively on surfaces. Swarming and swimming motility of bacteria has been studied well for rigid, self-propelled rods. In this study we report a strain of Vibrio alginolyticus, a species that exhibits similar collective motility but a fundamentally different cell morphology with highly flexible snake-like swarming cells. Investigating swarming dynamics requires high-resolution imaging of single cells with coverage over a large area: thousands of square microns. Researchers previously have employed various methods of motion analysis but largely for rod-like bacteria. We employ temporal variance analysis of a short time-lapse microscopic image series to capture the motion dynamics of swarming Vibrio alginolyticus at cellular resolution over hundreds of microns. Temporal variance is a simple and broadly applicable method for analyzing bacterial swarming behavior in two and three dimensions with both high-resolution and wide-spatial coverage. This study provides detailed insights into the swarming architecture and dynamics of Vibrio alginolyticus isolate B522 on carrageenan agar that may lay the foundation for swarming studies of snake-like, nonrod-shaped motile cell types.     

Swarming behavior in plant roots

Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming.     

Inactivation of ompR promotes precocious swarming and flhDC expression in Xenorhabdus nematophila

The response regulator OmpR is involved in numerous adaptive responses to environmental challenges. The role that OmpR plays in swarming behavior and swarm-cell differentiation in the symbiotic-pathogenic bacterium Xenorhabdus nematophila was examined in this study. Swarming began 4 h sooner in an ompR mutant strain than in wild-type cells. Precocious swarming was correlated with elevated expression of fliC, early flagellation, and cell elongation. The level of flhDC mRNA was elevated during the early period of swarming in the ompR strain relative to the level in the wild type. These findings show that OmpR is involved in the temporal regulation of flhDC expression and flagellum production and demonstrate that this response regulator plays a role in the swarming behavior of X. nematophila.     

Collective motion of bacteria in two dimensions

Collective motion can be observed in biological systems over a wide range of length scales, from large animals to bacteria. Collective motion is thought to confer an advantage for defense and adaptation. A central question in the study of biological collective motion is how the traits of individuals give rise to the emergent behavior at population level. This question is relevant to the dynamics of general self-propelled particle systems, biological self-organization, and active fluids. Bacteria provide a tractable system to address this question, because bacteria are simple and their behavior is relatively easy to control. In this mini review we will focus on a special form of bacterial collective motion, i.e., bacterial swarming in two dimensions. We will introduce some organization principles known in bacterial swarming and discuss potential means of controlling its dynamics. The simplicity and controllability of 2D bacterial behavior during swarming would allow experimental examination of theory predictions on general collective motion.     

Extracellular proteolytic activity plays a central role in swarming motility in Bacillus subtilis

Natural isolates of Bacillus subtilis exhibit a robust multicellular behavior known as swarming. A form of motility, swarming is characterized by a rapid, coordinated progression of a bacterial population across a surface. As a collective bacterial process, swarming is often associated with biofilm formation and has been linked to virulence factor expression in pathogenic bacteria. While the swarming phenotype has been well documented for Bacillus species, an understanding of the molecular mechanisms responsible remains largely isolated to gram-negative bacteria. To better understand how swarming is controlled in members of the genus Bacillus, we investigated the effect of a series of gene deletions on swarm motility. Our analysis revealed that a strain deficient for the production of surfactin and extracellular proteolytic activity did not swarm or form biofilm. While it is known that surfactin, a lipoprotein surfactant, functions in swarming motility by reducing surface tension, this is the first report demonstrating that general extracellular protease activity also has an important function. These results not only help to define the factors involved in eliciting swarm migration but support the idea that swarming and biofilm formation may have overlapping control mechanisms.