稻田水生昆虫的采样技术方法与应用

稻田水生昆虫在稻田生态系统功能实现中发挥着重要的作用。本文基于作者对稻田生态系统中水生昆虫多样性研究,系统地介绍了稻田水生昆虫的生态位分布、定量研究与定性研究的采集技术方法与流程,为更好地开展稻田水生昆虫研究提供技术支撑。     

Associations between stream fish and benthos across environmental gradients in southern Ontario, Canada

1. The relationship between fish and benthic invertebrate communities in wadeable streams in southern Ontario, Canada, was examined using three independent and spatially distinct data sets. 2. Associations between fish and benthos were always significant when benthos were identified to family and often at the level of phylum. Identification to genus improved the strength of the fish–benthos association in one case. In contrast, identification to species did not improve the strength of the fish–benthos association. Associations between benthos and fish were weaker for one study utilizing a ‘rapid’ bio-assessment protocol involving field sorting and identification, and a second study which utilized winter benthic collections. 3. In two surveys, stream temperatures were important to the distributions of both fish and benthos, while in a third survey, fish and benthos were primarily influenced by stream size. In all three studies, fish and benthos were associated with similar suites of environmental variables, suggesting that the fish–benthos associations in these streams was driven by corresponding environmental tolerances. 4. Although there was significant variation in the strength of the fish–benthos association which could be attributed to differences in sampling methodologies, the findings from the present study confirm that stream fish and benthos are significantly associated. Therefore, surveys of benthos can be used to make inferences on the condition of fish community composition.     

PKB: a program system and data base for analysis of protein structure

PKB is a computer program system that combines a data base of three-dimensional protein structures with a series of algorithms for pattern recognition, data analysis, and graphics. By typing relatively simple commands the user may search the data base for instances of a structural motif and analyze in detail the set of individual structures that are found. The application of PKB to the study of protein folding is illustrated in three examples. The first analysis compares the conformations observed for a short sequential motif, sequences similar to the cell-attachment signal Arg-Gly-Asp. The second compares sequences observed for a conformational motif, a 16-residue beta alpha beta unit. The third analysis considers a population of substructures containing ion-pair interactions, examining the relationship of frequency of occurrence to calculated electrostatic energy.     

A method for reconstructing three-dimensional positions of swarming mosquitoes

We developed a new field method for reconstructing the three-dimensional positions of swarming mosquitoes. This method overcame certain inherent difficulties accompanied by conventional stereoscopic methods and is applicable to three-dimensional measurements of other insect species. Firstly, we constructed a probabilistic model for stereoscopy; if mosquitoes and six reference points with known coordinates were photographed simultaneously from two or more perspectives, then from the positions of images of mosquitoes and the reference points on the photographs, 1) the position of each camera with respect to the reference points is estimated; 2) stereo images which correspond to an identical real mosquito are matched; and 3) the spatial positions of the mosquitoes are determined. We automated the processes 1), 2) and 3), developing computer programs based on our model. We then constructed a portable system for three-dimensional measurements of swarming mosquitoes in the field. Initial data that illustrate the application of our method to studying mosquito swarming were presented.     

Automated Correlation and Averaging of Three-Dimensional Reconstructions Obtained by Electron Tomography

We have developed a least-squares refinement procedure that in an automated way performs three-dimensional alignment and averaging of objects from multiple reconstructions. The computer implementation aligns the three-dimensional structures by a two-step procedure that maximizes the density overlap for all objects. First, an initial average density is built by successive incorporation of individual objects, after a global search for their optimal three-dimensional orientations. Second, the initial average is subsequently refined by excluding individual objects one at a time, realigning them with the reduced average containing all other objects and including them into the average again. The refinement is repeated until no further change of the average occurs. The resulting average model is therefore minimally biased by the order in which the individual reconstructions are incorporated into the average. The performance of the procedure was tested using a synthetic data set of randomly oriented objects with Poisson-distributed noise added. The program managed well to align and average the objects at the signal/noise ratio 1.0. The increase in signal/noise ratio was in all investigated cases almost equal to the expected square root of the number of objects. The program was also successfully tested on a set of authentic three-dimensional reconstructions from anin situspecimen containingEscherichia coli70S ribosomes, where the immediate environment of the reconstructed objects may also contain variable amounts of other structures.     

吉林蛟河阔叶红松林样地种-面积关系

种-面积关系是群落生态学的核心问题之一,是生物多样性尺度转换的重要依据。利用吉林蛟河阔叶红松林30 hm~2的样地数据,采用随机取样与巢式取样方法,分别在10、20、30 hm~2尺度上建立对数模型(Logarithmic function)、幂函数模型(Power function)和逻辑斯蒂模型(Logistic function)拟合局域种-面积关系,并利用赤池信息准则(AIC)进行拟合结果优度检验。结果表明,取样方法对种-面积关系的构建有显著影响,随机取样优于巢式取样。种-面积关系的构建与尺度(取样上限)密切相关:在小尺度上(10 hm~2),对数模型与逻辑斯蒂模型拟合效果优于幂函数模型;在中尺度和大尺度上(20、30 hm~2),相对于对数模型和幂函数模型,逻辑斯蒂模型能更好地拟合阔叶红松林的种-面积关系。据AIC值可知,随机取样下的逻辑斯蒂模型拟合效果最好,是拟合30 hm~2阔叶红松林样地种-面积关系的最适模型。因此研究时需要根据区域森林群落的实际情况选择种-面积模型。     

A method for determining the positions of polar hydrogens added to a protein structure that maximizes protein hydrogen bonding.

An automated method for the optimal placement of polar hydrogens in a protein structure is described. This method treats the polar, side chain hydrogens of lysine, serine, threonine, and tyrosine and the amino terminus of a protein. The program, called NETWORK, divides the potential hydrogen-bonding pairs of a protein into groups of interacting donors and acceptors. A search is conducted on each of the local groups to find an arrangement which forms the most hydrogen bonds. If two or more arrangements have the same number of hydrogen bonds, the arrangement with the shortest set of hydrogen bonds is selected. The polar hydrogens of the histidyl side chain are specifically treated, and the ionization state of this residue is allowed to change, if this change results in additional hydrogen bonds for the local group. The program will accept Protein Data Bank as well as Biosym-format coordinate files. Input and output routines can be easily modified to accept other coordinate file formats. The predictions from this method are compared to known hydrogen positions for bovine pancreatic trypsin inhibitor, insulin, RNase-A, and trypsin for which the neutron diffraction structures have been determined. The usefulness of this program is further demonstrated by a comparison of molecular dynamics simulations for the enzyme cytochrome P-450cam with and without using NETWORK.     

Sample coherence – a field study approach to assess similarity of macroinvertebrate samples

The EU-funded STAR-project provided an opportunity to analyse 1418 macroinvertebrate samples from 310 sampling sites throughout Europe. At most of the sites, samples were taken in two seasons using both national protocols and the project’s STAR-AQEM protocol. At a subset of sites (86), two replicate samples were taken by each method in each of the two seasons. The resulting taxalists were analysed in terms of community similarity using the Bray–Curtis Index, Jaccard, and Renkonen Indices. A new concept of sample ‘coherence’ is used to measure the relative strength of within-site, within-season and within-method similarity and to determine their importance on variability in community composition. Site-coherence (i.e., highest similarity to another sample from the same site) was much higher where replicate samples were available. Season-coherence of samples was nearly 100% even if different methods were compared. Season appeared to be one of the major determinants of in-stream fauna. The STAR-AQEM method is most comparable to the Nordic, Portuguese and Czech (PERLA) national methods and less comparable to the Italian (IBE) and Latvian methods. Samples collected by these latter methods had higher similarities to other sites sampled with the same methods than to samples of the same site using the STAR-AQEM method, thus there was low site-coherence. In three stream types from Italy, Latvia and Greece 28–38% of the samples were most similar to a sample from a different site than to a replicate sample from the same site. This fact could have serious consequences for follow up bioassessments or impact assessments by cluster analysis based on similarity measures. Replicate samples are less coherent within site, season or method if the taxonomic resolution is family rather than species. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Short,medium and long range transported airborne particles in viability and antigenicity analyses

Summary It is no longer enough that aerobiologists identify pollen grains and fugal spores under the microscope. They are expected to serve as well allergologists, who want to known about the concentrations of various allergens in the air samples, as meteorologists, who need to know about the frequency of primary biological aerosols, which may act in radiative forcing of the atmosphere. Methods utilized by the aerobiologists vary from immunochemical analyses, culture and germination to infecting host plants with certain pathogens. Difficulties to separate between short, medium and long range transport of airborne particles on the basis of their viability are discussed.