荧光标记的染色体原位杂交及其在人类基因组研究中的应用

FISH技术是80年代开始发展起来的一种新的定位技术.在人类基因组研究中得到了广泛的应用.通过中期染色体的FISH可以进行SCP,Cosmid和YAC的染色体定位,嵌合克隆的鉴别;通过间期核的FISH可以在50kb的分辨率下进行基因作图;最新的研究进展已可以进行伸展的染色质丝(chromatin fibre)的FISH,直接测量基因的长度,从而达到高精度基因作图的目的.总之,随着FISH技术本身的发展,它将在人类基因组研究中发挥更大的作用.     

基于血流多普勒原理的血压测量系统设计

血流信号的采集可基于超声多普勒技术。利用多普勒超声探头在肢体主动脉脉搏处采集到血流多普勒频移信号,对信号电压进行放大,一方面直接输入扬声器转变为音频信号,得到多普勒音;同时用频率/电压变换器LM331变换多普勒频移信号,得到脉搏波信号。基于此原理,设计了使用无创、直观的方法获得肢体血流参数,并经PC机处理,最终在显示器上显示脉搏波形和血压数值的方法。     

Fluorescence in situ hybridization on vibratome sections of plant tissues

This protocol describes the application of fluorescence in situ hybridization (FISH) to three-dimensionally (3D) preserved tissue sections derived from intact plant structures such as roots or florets. The method is based on the combination of vibratome sectioning with confocal microscopy. The protocol provides an excellent tool to investigate chromosome organization in plant nuclei in all cell types and has been used on tissues of both monocot and dicot plant species. The visualization of 3D well-preserved tissues means that cell types can be confidently identified. For example, meiocytes can be clearly identified at all stages of meiosis and can be imaged in the context of their surrounding maternal tissue. FISH can be used to localize centromeres, telomeres, repetitive regions as well as unique regions, and total genomic DNAs can be used as probes to visualize chromosomes or chromosome segments. The method can be adapted to RNA FISH and can be combined with immunofluorescence labeling. Once the desired plant material is sectioned, which depends on the number of samples, the protocol that we present here can be carried out within 3 d.     

Eradication and control of livestock ticks: biological, economic and social perspectives

Comparisons of successful and failed attempts to eradicate livestock ticks reveal that the social context of farming and management of the campaigns have greater influence than techniques of treatment. The biology of ticks is considered principally where it has contributed to control of ticks as practiced on farms. The timing of treatments by life cycle and season can be exploited to reduce numbers of treatments per year. Pastures can be managed to starve and desiccate vulnerable larvae questing on vegetation. Immunity to ticks acquired by hosts can be enhanced by livestock breeding. The aggregated distribution of ticks on hosts with poor immunity can be used to select animals for removal from the herd. Models of tick population dynamics required for predicting outcomes of control methods need better understanding of drivers of distribution, aggregation, stability, and density-dependent mortality. Changing social circumstances, especially of land-use, has an influence on exposure to tick-borne pathogens that can be exploited for disease control.     

Measurement of soil macropore geometry by image analysis of sections through impregnated soil

The geometry of the soil pore space affects root growth directly by providing pathways for root extension and indirectly through its effects on soil aeration and on water infiltration, redistribution and drainage. Image analysis of sections through impregnated blocks of undisturbed soil allows quantitative assessment of the pore space. Samples are dehydrated and impregnated with resin containing a fluorescent dye. Once the resin has hardened, the blocks can be cut to reveal a section through the structure. An image of the pore space, which is now filled with resin, can be obtained using ultra-violet light either photographically or digitally. Digital images are segmented into pore space and solid. Image analysis techniques can be used to classify the pore space into channels, fissures and packing pores. This allows appropriate measurements to be made on each class so that stereology can be used to estimate 3-D parameters from the measurements made on the image. Various indices can also be derived to quantify the pore structure.     

The use of biomarkers in surveillance, medical screening, and intervention

Building on mechanistic information, much of molecular epidemiologic research has focused on validating biomarkers, that is, assessing their ability to accurately indicate exposure, effect, disease, or susceptibility. To be of use in surveillance, medical screening, or interventions, biomarkers must already be validated so that they can be used as outcomes or indicators that can serve a particular function. In surveillance, biomarkers can be used as indicators of hazard, exposure, disease, and population risk. However, to obtain rates for these measures, the population at risk will need to be assessed. In medical screening, biomarkers can serve as early indicators of disease in asymptomatic people. This allows for the identification of those who should receive diagnostic confirmation and early treatment. In intervention (which includes risk assessment and communication, risk management, and various prevention efforts), biomarkers can be used to assess the effectiveness of a prevention or control strategy as well as help determine whether the appropriate individuals are assigned to the correct intervention category. Biomarkers can be used to provide group and individual risk assessments that can be the basis for marshalling resources. Critical for using biomarkers in surveillance, medical screening, and intervention is the justification that the biomarkers can provide information not otherwise accessible by a less expensive and easier-to-obtain source of information, such as medical records, surveys, or vital statistics. The ability to use validated biomarkers in surveillance, medical screening, and intervention will depend on the extent to which a strategy for evidence-based procedures for biomarker knowledge transfer can be developed and implemented. This will require the interaction of researchers and decision-makers to collaborate on public health and medical issues.     

Analysis of extracellular potentials using an IBM PC

1. A system has been developed for using IBM PC-compatible computers in combination with a Grafitek Data Logging Interface to record spike trains on magentic discs for later analysis. 2. The times and amplitudes of spikes detected on two input channels are recorded, together with a third channel containing information on computer-generated stimuli and keyboard-activated event markers. In excess of 50,000 spikes can be recorded with a computer having 640 k of Random Access Memory. 3. The recorded spike trains can be reconstructed on the computer monitor and keyboard-controlled window discriminators can be used to select the spikes for analysis by amplitude. 4. The same recorded data can be analysed to produce displays of spike count against time, amplitude histograms, inter-spike interval histograms, peri-stimulus time histograms(PSTH), raster displays and auto- and cross-correlations between activity on the two channels. Each spike is identified by number, allowing easy location of the start and finish of the section of data to be analysed, and the PSTH, raster and correlation analyses allow pretriggering to investigate event occurring before stimulation. 5. The axes of the displays histograms can be adjusted to produce optimum displays, and hard copy can be produced on dot matrix printers or digital plotters. 6. Quantitative analysis enables comparison between different recordings and treatments.     

Use of bioluminescence in nucleic acid hybridization reactions

Luminescence reactions can be used to detect specific nucleic acid sequences hybridized with a nucleic probe. Different labels such as cytidine sulphone, fluorescein, and biotin can be incorporated into DNA or oligonucleotide molecules and detected by antibody or avidin conjugates coupled to glucose-6P dehydrogenase. On supports such as nitrocellulose filters, sensitivity is not greatly increased using luminescence, but detection is rapid and easy to perform using polaroid film. Moreover, hybridization can be performed with different labelled probes on the same sample. In solution, luminescence can be used to monitor sandwich reactions. The method is less sensitive than detection on filters but can easily be automated. The performance of these assays can be increased considerably by enzymatic amplification of the target catalysed by a thermostable polymerase.     

Modeling cell concentration in complex media

A model that continuously predicts the concentration of microorganisms in complex medium fermentations is suggested. The model uses carbon dioxide evolution as its primary input and assumes that respiration activity can be differentiated into growth-related and maintenance-related functions. This model can be programmed on computer-coupled vessels and used to standardize on a physiological fermentation inoculum transfer time. The cell concentration estimate can also be used to calculate specific growth rate and can be combined with additional monitored information to calculate other important fermentation parameters such as specific oxygen uptake.     

Weak alignment offers new NMR opportunities to study protein structure and dynamics

Protein solution nuclear magnetic resonance (NMR) can be conducted in a slightly anisotropic environment, where the orientational distribution of the proteins is no longer random. In such an environment, the large one-bond internuclear dipolar interactions no longer average to zero and report on the average orientation of the corresponding vectors relative to the magnetic field. The desired very weak ordering, on the order of 10(-3), can be induced conveniently by the use of aqueous nematic liquid crystalline suspensions or by anisotropically compressed hydrogels. The resulting residual dipolar interactions are scaled down by three orders of magnitude relative to their static values, but nevertheless can be measured at high accuracy. They are very precise reporters on the average orientation of bonds relative to the molecular alignment frame, and they can be used in a variety of ways to enrich our understanding of protein structure and function. Applications to date have focused primarily on validation of structures, determined by NMR, X-ray crystallography, or homology modeling, and on refinement of structures determined by conventional NMR approaches. Although de novo structure determination on the basis of dipolar couplings suffers from a severe multiple minimum problem, related to the degeneracy of dipolar coupling relative to inversion of the internuclear vector, a number of approaches can address this problem and potentially can accelerate the NMR structure determination process considerably. In favorable cases, where large numbers of dipolar couplings can be measured, inconsistency between measured values can report on internal motions.     

Modification of commerical and custom-built slab gel electrophoresis units for two-dimensional polyacrylamide gel electrophoresis

Many commercial and custom-built slab gel electrophoresis units can be modified to function as two-dimensional polyacrylamide gel electrophoresis units with the insertion of Plexiglas adapters. These adapters can be made for about $50 a pair and can be used for either temporary or permanent modification of the slab gel units. The physical dimensions of the adapters can be varied to permit great flexibility in the diameter of cylinder gels and the thickness of slab gels that can be run together. For example, proteins from 6-mm cylinder gels can be easily separated on 1-mm slab gels, which can then be dried for autoradiography.     

高密度基因芯片探针布局方法

为了提高基因芯片制备质量和检测的准确性,提出两种基因芯片布局方法,一是分子印章凸点优化布局方法,另一种是基于探针杂交解链温度的梯度场布局方法。利用上述两种方法对所设计的高密度基因芯片进行控针布局实验,结果表明,第一种方法能够使制备基因芯片的分子印章上凸点均匀分布,解决误压印问题,从而提高基因芯片的制备质量;而第二种方法能够使基因芯片上的探针按照杂交解链温度有序地组织起来,从而提高基因芯片对碱基错配的辨别力。     

Rapid multivariate analysis and display of cross-reacting antibodies on human leukocytes.

We present an application which can rapidly determine the binding patterns of monoclonal antibodies on mixed populations of cells simultaneously in a single rapid analysis. It is an application of the tube identifier parameter (TIP) system which can provide fully correlated list-mode data of the entire patient phenotype in a single file. Using the phenogram analytical display, we are able to determine the cross-reacting antibodies for an entire antibody panel for each cell type. This information can be displayed in a single plot. Using light scatter gating to select different populations of lymphocytes, monocytes, and neutrophils, phenograms can be simultaneously generated. This provides a directly comparable means of displaying the positive and negative binding characteristics of each antibody on each cell population. Any marker combination that is abnormal will be identifiable in the phenogram. Additionally, by plotting the fluorescence distributions of each marker beside one another (termed overview), quantifiable differences in intensity can be determined. There are 3 major benefits of the proposed analysis. By using the TIP concept, several sets of antibodies can be compared simultaneously. Any light scatter gate can be used and this gate can be changed on one histogram or plot, yet apply to the total analysis. Data analysis is particularly rapid since the entire phenotype of a patient can be evaluated by performing a single rapid analysis.     

毛细管电泳在细菌分离分析中的应用

介绍了近年来毛细管电泳技术在细菌分离分析方面的研究进展。毛细管电泳以细菌表面的特征信息为分离的基础,可以快速鉴定相应的菌株,可以对微生物进行快速定量,可以反映细菌特殊时期的生理特征,也可以研究微生物与分子之间的相互作用。同时应用该技术可分离分析自然界不能纯培养的微生物。因而毛细管电泳分离与检测细菌方法的建立及其应用在分离科学和微生物学方面都有很大的实际意义。     

On Some Logical Uncertainties in Genetics and their Significance

Amylose azure can be used as a chromogenic substrate for α-amylase in studying the effects of temperature and pH on enzyme action. This is a model system which students can use to measure the energy of activation using the Arrhenius plot. The temperature coefficient can also be determined. Further laboratory investigations can be designed to measure optimum pH under varying conditions and the effects of activators on the system.

This paper reviews a-amylase action with respect to temperature and pH. Further investigations are suggested.     

Diagnostic laboratory parasitology--a stepping stone to medical research in tropical Africa.

African countries can concentrate mainly on operational and problem-solving type of medical research using as a basis routine diagnostic laboratory parasitology which can be elevated to research level by incorporating all relevant techniques backed by statistically-based programming. Because of high incidence of parasitic infections and the peculiar host-parasite relationship, co-operation between all departments of any major hospital will be required to deal with the diseases due to them. Longitudinal studies on some parasites will enable generalisation and specific views to be formed on some infections. Multiplicity and wide variety of available techniques offer several research possibilities of clinico-pathological and epidemiological significance. Routine laboratory-based research offers the right environment for training various types of laboratory workers from technicians to medical parasitologists, through on-the-job training on techniques, investigative studies and research, backed by formal lectures and practicals at various levels. Trainee medical parasitologists can obtain higher degrees locally or abroad. The research can be organised around micro and mini research units. This approach is cost-beneficial because it minimises administrative difficulties and so avoids wastage. The results can be used to monitor impact of national development on parasitic infection prevalence and to formulate a policy on parasitic disease management.     

Neural Coding with Graded Membrane Potential Changes and Spikes

The neural encoding of sensory stimuli is usually investigated for spike responses, although many neurons are known to convey information by graded membrane potential changes. We compare by model simulations how well different dynamical stimuli can be discriminated on the basis of spiking or graded responses. Although a continuously varying membrane potential contains more information than binary spike trains, we find situations where different stimuli can be better discriminated on the basis of spike responses than on the basis of graded responses. Spikes can be superior to graded membrane potential fluctuations if spikes sharpen the temporal structure of neuronal responses by amplifying fast transients of the membrane potential. Such fast membrane potential changes can be induced deterministically by the stimulus or can be due to membrane potential noise that is influenced in its statistical properties by the stimulus. The graded response mode is superior for discrimination between stimuli on a fine time scale.     

Hybridization-based karyotyping of mouse chromosomes: hybridization-bands.

We have developed a method, which we have named hybridization-banding, to identify simultaneously all chromosomes in a mouse metaphase spread. The method uses a combination of hybridization probes labeled with a single fluor to yield a simple, unique, readily identifiable hybridization pattern on each chromosome. The method is superior to Giemsa- or fluorescence-based banding methods for chromosome identification because the hybridization patterns are simpler and easier to identify, and unique patterns can be designed at will for each chromosome. Analysis can be performed with a standard fluorescence microscope, and images can be recorded on film with an ordinary 35-mm camera, making the method useful to many investigators. The method can also be applied to any species for which chromosomes and probes can be prepared.     

概率布尔型基因调节网络的分解方法研究

基于Iyla Shumlevich等提出的概率布尔型网络(PBN)模型,计算网络中任意两基因之间量化了的相互影响,给出相应的有向带权图模型。通过对模型的标准化分析,找出关键节点,以各关键节点为中心,对网络划分,通过计算子网络间交互信息,确定各子网络边界,以达到对网络的最优分解。     

Isoenzymes and migration in the African armyworm Spodoptera exempta (Lepidoptera, Noctuidae)

Techniques for the separation of proteins have proved to be powerful tools in the study of genetic variation. Polymorphisms on protein levels can be used to study the structure of populations. In general, differences in allele frequencies can be found among populations in different parts of the distribution area of a species. If, however, enough gene flow occurs by migration, the whole system can be regarded as one panmictic unit and similar frequencies can be expected in the whole area.
African armyworms are caterpillars of the noctuid moth Spodoptera exempta. They live on all sorts of graminaceous plants on which vast outbreaks can occur. Their economic importance can be considerable since they eat the main human food crops as well as pasture grasses. The occurrence of migration in S. exempta is known but its importance is a main controversial point. Outbreaks move during the year. These outbreaks could be caused by migrating animals or by increasing local populations when conditions are favourable.
The aim of this study has been to determine the relative importance of migration. Allele frequencies have been determined of six alleloenzymes that proved to be genetically polymorphic, an EST, 0-HBDH, ODH, a-GPDH, ME and LDH. Seventeen armyworm samples have been collected at a maximal distance of 2000 km in Kenya, Tanzania and Rhodesia on different food plants during 1975 and 1976.
No heterogeneity among these samples could be detected in the allele frequencies. A comparison with data from relevant literature on insects showed that the lack of heterogeneity cannot be described to inadequacy of the data. The occurrence of extensive migration is concluded to cause the similarity in allele frequencies.