七种白蚁消化道解剖形态的比较研究

本文对采自浙江省的7种白蚁（东方原白蚁、黄肢散白蚁、黑胸散白蚁、肖若散白蚁、家白蚁、杨之江近歪白蚁和和大鼻象白蚁）的消化道形态进行了解剖比较研究。并初步探讨了白蚁消化道形态在白蚁系统发育和进化中的意义。     

Magnetite biomineralization in termites

Experimental evidence exists for magnetoreception in termites, a major component of the soil macrofauna in many tropical countries. This preliminary study identifies, probably for the first time, the presence of biogenic ferrimagnets (magnetite?) in two species of termite (Nasutitermes exitiosus and Amitermes meridionalis), based on magnetic measurements of whole termite specimens and individual body sections, and analysis by electron microscopy of magnetically extracted grains. The magnetic measurements indicate the presence of very small concentrations of magnetic material, with more magnetic grains in the thorax and abdomen region compared with the head. Magnetic interaction, due to clustering of grains, is also identified by the measurements. Analysis of magnetic extracts by transmission electron microscopy identifies the presence of uniquely ultrafine (10 nm) and unidimensional grains of ferrimagnetic material, unequivocally distinct from any possible extraneous magnetite sources, such as ingested soil. Hence, this provides firm evidence for biogenic formation of this magnetic material by these two termite species. Such ultrafine grains would be superparamagnetic, i.e. incapable of carrying a permanent magnetic moment, unless they were sited in clusters of interacting grains, when some remanence-carrying ability, and hence magnetotaxis, would be possible.     

Chemical warfare in termites

The rapid development of analytical methods in the last four decades has led to the discovery of a fascinating diversity of defensive chemicals used by termites. The last exhaustive review on termite defensive chemicals was published by G.D. Prestwich in 1984. In this text, we aim to fill the gap of the past 25 years and overview all of the relevant primary sources about the chemistry of termite defense (126 original papers, see Fig. 1 and online supplementary material) along with related biological aspects, such as the anatomy of defensive glands and their functional mechanisms, alarm communication, and the evolutionary significance of these defensive elements.     

Imported wood decomposition by termites in different agro-eco zones of India

Some imported timbers are well known for their durability and their reputation has carried them far from their original homes, although some have not maintained their reputation under different conditions or where new varieties of termites have appeared. It is necessary to know the behaviour of wood species under different environmental conditions and their durability class before the timber or timber product is put into use. The degree of wood deterioration is dependent on conditions such as soil, rainfall, altitude, temperature, and other environmental conditions under which the timber is put to use. Natural durability refers to the ability of wood species to resist attack by different agents, especially biological ones. This paper describes the natural resistance of important imported timber species of India against termites in different agro-eco zones. Field experiments were carried out at six locations falling under five Indian agro-eco zones with the aim of evaluating the natural resistance of 20 species of imported woods. Wood stakes measuring 30.5 × 3.8 × 3.8 cm as per IS:401-1982 standards were implanted in the soil and observed for a period of 4 yr, and visual damage assessment was done. The termites active in the test yard and on the test stakes were collected, preserved in 70% ethanol, and identified using taxonomic keys. Results revealed significant variation in rate of degradation of wood species with climatic zones producing significant variation as well. The tested timbers were categorized into three groups: susceptible, resistant, and moderately resistant. Termites collected belonged to nine species under four genera and the single family Termitidae. Odontotermes obesus was the dominant species in most of the locations.     

Nuclear architecture by RNA

The dynamic organization of the cell nucleus into subcompartments with distinct biological activities represents an important determinant of cell function. Recent studies point to a crucial role of RNA as an architectural factor for shaping the genome and its nuclear environment. Here, we outline general principles by which RNA organizes functionally different nuclear subcompartments in mammalian cells. RNA is a structural component of mobile DNA-free nuclear bodies like paraspeckles or Cajal bodies, and is involved in establishing specific chromatin domains. The latter group comprises largely different structures that require RNA for the formation of active or repressive chromatin compartments with respect to gene expression as well as separating boundaries between these.     

Directional selection by termites at a branching node created by a ballpoint pen

Subterranean termites excavate complex underground tunnels for foraging. Most tunnels comprise primary and secondary tunnels. Tunnels originating from the nest are called primary and those branching from the primary tunnels are named secondary tunnels; tertiary and quaternary tunnels are rarely observed. During foraging, termites may thus encounter a considerable number of tunnel-branching nodes. Directional selection at such a node is likely correlated to tunnel-growth activity because tunnels containing more termites have a higher probability of growth. In this study, we investigated how termites select the direction of movement at an artificially-designed branching node, by making chemical trails on filter paper, drawing lines using a ballpoint pen which contained the chemical substance that induces the termite to follow trails. The trails consisted of two lines: straight and branching. The branching line was drawn from the center of the straight line at an angle θ (10°, 20°,…, 90°). We then calculated the ratio of the directional selection as r = N_s/N_b, where N_s and N_b represent the number of straight and branching tunnels selected, respectively. The values of r were statistically classified into three groups based on the angle of the branching trail, as follows: 10° ≤ θ ≤ 20°, 30° ≤ θ ≤ 60°, and 70° ≤ θ ≤ 90°. Our paper briefly discusses the underlying mechanisms of the experimental results.     

Conditioning shelter dogs to sit

Human contact in the shelter may lessen effects of change in environment and smooth transition into a home. Training can increase a dog's interaction with people in a shelter environment. Experiments were conducted to determine how rapidly shelter dogs learn to sit, if the dogs can retain sitting behavior over time, and if sitting transfers to novel locations and people. Two experiments trained shelter dogs (n = 21) to sit when a stranger approached over a 10-trial session. Food and a verbal cue or a clicker reinforced the sit. The experiments measured latency to sit for each trial. Latency to sit decreased significantly over trials. Another experiment included reinforcement given to dogs (n = 20) on a noncontingent basis or for sitting. Five days of the experiment (condition training) were in the same room with the same experimenter. The last 4 days (testing) varied by both experimenter and location (familiar or strange). Results indicate that short training sessions are effective for teaching shelter dogs to sit, that dogs can retain sitting behavior over 2 days, and that training transfers to novel people and situations.     

The effect of coral morphology on shelter selection by coral reef fishes

While the loss of structural complexity causes declines in coral reef fish diversity, the processes leading to this decline are largely unexplained. To explore the role of coral morphology in providing shelter for fishes, tabular, branching and massive corals were filmed with video cameras and their usage by large reef fishes compared. Tabular corals were utilised more than the other two morphologies, with at least triple the abundance, biomass and residence times of large fishes. The preference of coral reef fishes for specific structural traits of tabular corals was also examined using artificial structural units. This experimental component showed that large reef fishes preferred opaque rather than translucent canopies. It appears that large fishes cue to tabular corals because of the concealment and/or shade provided. It is suggested that a loss of tabular corals as a result of climate change would have significant ecological impacts for the coral reef fishes that use these structures for shelter.     

洞庭湖水系防护林树冠截留研究

运用雨量槽和虹吸自记仪对洞庭湖水系１８个主要防护林林分类型树冠截留进行了定点观测研究,建立了树冠截留随林外降水量的变化模型和树冠截留动态模型．７～８月多数林分树冠截留能力比４～６月大,且随不同时段和不同类型林分而异．不同林分树冠截留随林外降水的变化差异明显．     

Making tubes: step by step

Branched hollow tubes form the architectural basis of many mammalian organs. The growth factor HGF/SF and its receptor, the Met receptor tyrosine kinase, stimulate epithelial cells to undergo tubulogenesis in vitro. In this issue of Developmental Cell, O'Brien et al. (2004) look at temporal regulation and the role of two HGF/SF effectors, the ERK 1/2 MAP kinases and matrix metalloproteases, in this process.     

Orientation by pigeons deprived of olfaction by nasal tubes

Summary In an effort to avoid the trauma and other nonolfactory effects produced by surgical sectioning of pigeons' olfactory nerves, and to avoid the interference with breathing produced by nostril plugs, a way of making pigeons anosmic by inserting plastic tubes in their nostrils was developed. A total of 16 experimental releases were conducted from unfamiliar sites to compare the homing behavior of birds wearing a tube in each nostril with controls wearing a tube in only one nostril. In five short-distance releases (less than 25 km), no convincing differences in initial orientation, vanishing intervals, or homing success were observed. In eleven releases from longer distances (more than 76 km), the experimental birds were random in three cases and the controls were random in two. In no case were the differences in the distributions of the bearings of experimental and control birds statistically significant, nor were there ever significant differences in vanishing intervals. However, experimental birds had much poorer homing success from these long-distance releases. It is concluded, in view of the anosmic pigeons' good orientation at distant unfamiliar sites, that olfaction is not necessary for homeward orientation and hence that it cannot be the basis of the birds' navigational map. Poor homing success from long distances is probably a consequence of the physical irritation and interference with breathing unfortunately produced by the nasal tubes.We thank our colleagues, Irene Brown, Timothy Larkin, and André Gobert for their help in conducting the releases. This research was supported by Grant BMS 75 18905 AO2 from the National Science Foundation.     

白蚁防治技术

白蚁是破坏性很强的社会性昆虫。文章从白蚁的探测和监测、物理防治、化学防治、生物源物质防治和白蚁信息素的利用技术5个方面综述白蚁防治技术的最新研究进展。同时展望白蚁未来的研究领域。     

The role of termites in tropical forestry

Summary Tropical forestry is influenced by termites in widely differing ways.Large mounds constructed byMacrotermes in Africa and Asia are ecological factors which influence the natural regeneration of forests and the vegetation patterns of savanna woodlands and grasslands.Economic losses in timber caused by termite attack on mature trees are restricted to those areas in Australia, Asia and Central America where particular species ofCoptotermes are present.Afforestation withEucalyptus in less humid areas of Africa, India and South America has been greatly facilitated by the use of organochlorine insecticides to protect seedlings and saplings from attack by ground-dwelling termites.

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Zusammenfassung Für die tropische Forstwirtschaft ist eine Reihe von Termitenarten in unterschiedlicher Weise bedeutsam.Dis grossen Termitenhügel vonMacrotermes sind in Afrika und Asien ökologisch von grosser Wichtigkeit, indem sie die Regeneration des Waldes und die Vegetationsverteilung in Trockensavannen und Grasland beeinflussen.Wirtschaftliche Holzschäden durch Termitenangriff auf stehende Waldbäume beschränken sich in Australien, Asien und Zentralamerika auf solche Gebiete, in denen best-immteCoptotermes-Arten vorkommen.Die Aufforstung mit Eucalyptusarten in Afrika, Indien und Südamerika ist wesentlich erleichtert worden, seitdem man dazu übergegangen ist, die Sämlinge und Jungbäumchen durch verschiedene organischsynthetische-Boden-Insektizide zu schützen.

     

白蚁的分子生物学研究进展

白蚁是危险性社会昆虫,建立安全有效的白蚁防治方法有赖多学科的参与,分子生物学已经成为白蚁研究的重要工具。目前,DNA序列分析方法已应用于白蚁鉴定和分类,其中线粒体基因是最通用的分子标记;基因工程技术成功构建了可用于白蚁防治的白蚁肠道工程菌;Hexamerin、COX Ⅲ、纤维素酶等白蚁功能基因以及白蚁品级分化相关的若干蛋白相继得到了分离和鉴定。文章从白蚁分类、防治、功能基因、品级分化4个方面综述白蚁分子生物学的研究进展,为白蚁的防治提供新的方法和思路。     

Interference competition in desert subterranean termites

We examined interspecific aggression between two subterranean termite species, Heterotermes aureus (Snyder) (Rhinotermitidae) and Gnathamitermes perplexus (Banks) (Termitidae). In laboratory tests with worker termites, neither species was the inherently superior fighter, but rather the outcome of interspecific encounters depended on the number of conspecifics. We then investigated patterns of resource use by these species during a 13-month period in the Sonoran Desert. Baits consisted of toilet-paper rolls, which have been shown to be a mutually acceptable food source. Analyses of foraging activity demonstrated that the two species did not forage independently of each other. Not only were the two species negatively associated spatially, but extended periods of temporal segregation were observed. G. perplexus took significantly longer to return to sites that it had simultaneously occupied with H. aureus than to sites that G. perplexus had occupied alone. The pattern of co-occurrence of these two species is consistent with the hypothesis that interspecific interference competition affects their spatial and temporal distribution.     

Morphological phylogenetics of termites (Isoptera)

Isoptera (termites) are an ecologically important order, with both a high abundance and biomass in tropical ecosystems. However, there have been few phylogenetic hypotheses for termites, and we present here the first comprehensive cladistic analysis for the group. We analysed relationships between all seven termite families, including representatives of all known feeding group, plus a number of systematically critical taxa. Termite species richness is biased towards the higher termites (Termitidae), and our taxon sampling reflects this. Our analysis was based essentially on morphological characters (96 workers, 93 soldiers) plus seven biological characters. The cladistic analysis gave four equally parsimonious trees, representing two islands of topologies. The strict consensus tree is fully resolved for the higher termites, but less so for the lower termites. Overall there is low statistical support for the suggested topology, and this can be explained by the high incongruence between the data sets (worker, soldier and biological). This study highlights the particular problems of coding morphological characters in social insects with multiple castes. Without the input of additional data sets, e.g. alates, biological, behavioural and molecular, it will not be possible to obtain a well-supported termite phylogeny.