Amyloid fibrils of the HET-s(218-289) prion form a beta solenoid with a triangular hydrophobic core

Prion and nonprion forms of proteins are believed to differ solely in their three-dimensional structure, which is therefore of paramount importance for the prion function. However, no atomic-resolution structure of the fibrillar state that is likely infectious has been reported to date. We present a structural model based on solid-state nuclear magnetic resonance restraints for amyloid fibrils from the prion-forming domain (residues 218 to 289) of the HET-s protein from the filamentous fungus Podospora anserina. On the basis of 134 intra- and intermolecular experimental distance restraints, we find that HET-s(218-289) forms a left-handed beta solenoid, with each molecule forming two helical windings, a compact hydrophobic core, at least 23 hydrogen bonds, three salt bridges, and two asparagine ladders. The structure is likely to have broad implications for understanding the infectious amyloid state.     

Comparative study of the discriminating capacity and effectiveness of AFLP, STMS and EST markers in assessing genetic relationships among evergreen azaleas

The application of amplified fragment length polymorphism (AFLP), sequence tagged microsatellite site (STMS) and expressed sequence tag (EST) markers to study the genetic relationships in an evergreen azalea gene pool was investigated. STMS and EST markers revealed a higher genetic distance detection capacity than AFLPs, which, nevertheless, were the most efficient marker system due to their highest polymorphism detection capacity. Similarity matrices showed weak, yet significant, correlations when Mantel's test was applied. To assess the usefulness of the overall information provided by these marker data for establishing phylogenetic relationships and horticultural classification, cluster analysis was performed. The joint AFLP, STMS and EST data were demonstrated to be remarkably effective for group discrimination and phylogenetic studies. The use of these polymerase chain reaction marker systems is discussed in terms of the choice of appropriate marker techniques for different aspects of evergreen azalea germplasm evaluation.     

Soil monitoring in Germany

Background Aim and Scope

Soil monitoring in Germany should register the current soil condition, monitor its changes and provide a forecast for future development. In order to achieve these goals, the long-term soil monitoring sites in Germany (BDF -Bodendauerbeobachtungsflächen) have been established by the federal states. This has been done according to criteria worked out by soil monitoring experts. In this article a method for the examination of the suitability of Germany’s soil monitoring sites for soil conservation and protection purposes, as well as for environmental monitoring and reporting, is introduced. This method includes the landscape representativity of soil monitoring sites as well as the comparability and spatial validity of collected data.

Methods

BDF-criteria are operationalized in a three-step procedure: At first, a metadatabase is established containing information that allows the comparison of monitoring sites by means of measuring parameters, methods and quality assurance as well as quality control of measurements. Secondly, the representativity of the BDF-sites for soil types, land use, vegetation, and climate (air temperature, duration of sunlight, precipitation) by means of frequency statistics and neighborhood analysis is quantified. At last, the spatial validity of soil monitoring data is examined through the application of geostatistical methods. Both data and statistical methods are integrated in a Geoinformationsystem (GIS).

Results

The analysis of metadata reveals that the soil monitoring is of great importance for environmental analysis because of its ecosystematic concept and its considerable degree of methodical harmonization. Assuming that the number of BDF should be directly proportional to the areal portion of an ecoregion in the entire area of Germany, it can be shown that the geographical distribution of BDF-sites fit quite well according to the areal portions of the ecoregions. The maximum deviation is about ñ 6%. If the number of BDF is not proportional to the area covered by a certain combination of site characteristics, these areas can either be complemented or thinned through MNR-indices derived by neighborhood analysis. Soil monitoring sites can be added where the MNR are highest and removed where MNR are lowest. Throughout the neighborhood analysis, three GISmaps were processed: ecoregionaiization, soil types and land use. Decisions to reduce the spatial density of monitoring sites should not only be based on the landscape representativness of monitoring networks, but on the support of geostatistical analysis of measured data as well. For example, the results of the geostatistical analysis of Pb-concentrations in top soils are compared for a complete and a reduced BDF monitoring network.

Conclusion

The investigations show that not only the proportional distribution of monitoring sites in landscape units (landscape representativity) is important for the assessment of environmental monitoring networks; The number of monitoring sites, rather, should be sufficient to guarantee a spatial representation of the respective measurement variable. Their geographical distribution should be based on the spatial model of landscape units. Additionally, particular criteria that are important for the object of investigation, for example the distance to emitters, should also be considered.

Perspective

It is strongly recommended that activities for the integration of ecological data collected in diverse monitoring networks be intensified. A central German environmental information system should be established in order to realize integrated analysis of environmental data by aspects of harmonization and representativity. Furthermore, Internet and GIS technologies should be used to assist the environmental data acquisition in Germany. A prototype of such an instrument, the socalled Internet and GIS-based Environmental Monitoring System (IGUS) was already established and tested in the moss monitoring program 2000.

     

Die klassifizierung von bodenprofilen als grundlage agrarer standortplanung in Entwicklungsländern. Ein beispiel aus dem savannengebiet Nordost-Ghanas

One of the major tasks of experimental farms is the determination of productivity with regard to the regionally differing natural, technological, and socio-economic boundary conditions. In order to achieve this aim the location of the respective stations must be regionally representative from the viewpoint of the major factors controlling agrarian production. In paradigmatic representation, i.e. focusing the very interest on soil qualities and dealing with the north-eastern part of Ghana as a developing country, this article describes a cogent method for defining local representativity of production sites by means of classification procedures and biplot calculus. The application of the latter derivative of matrix calculus appears absolutely necessary for defining those results of clustering procedures which are interpretable in factual terms.     

Measurements of the bodyweight and other physical characteristics of 11 llamas (Lama glama) from birth to weaning

The bodyweight (bw), thoracic circumference, length and height of 11 llamas were recorded weekly from birth for 27 weeks. Their mean (sd) birth weight was 11.60 (2.35) kg and their weight increased in curvilinear fashion reaching 61.05 (13.75) kg after 27 weeks. Their average daily gains reached the highest value three weeks after birth and then decreased, reaching the lowest value of 262 g per day at 27 weeks. On a metabolic bw(0.83) basis, the growth of the llamas when their dams were at peak lactation was comparable with that of calves, fawns and lambs. All the measurements were significantly affected by the age, but not by the sex of the young or the parity of the dam. The regression models chosen to predict the bodyweight and weight gain of the llamas yielded R(2) ranging from 0.97 to 0.99. Correlations between bodyweight and other single body measurements were between r=0.68 and 0.77. Single or combined body measurements were good predictors of bodyweight, but additional body measurements added little to the already good fit provided by a single measurement (R(2) ranging from 0.93 to 0.98). The thoracic circumference (R(2)=0.98) and length (R(2)=0.96) were good predictors of the bodyweight of the llamas between birth and 27 weeks old.     

The big and the small: challenges of imaging the brain's circuits

The relation between the structure of the nervous system and its function is more poorly understood than the relation between structure and function in any other organ system. We explore why bridging the structure-function divide is uniquely difficult in the brain. These difficulties also explain the thrust behind the enormous amount of innovation centered on microscopy in neuroscience. We highlight some recent progress and the challenges that remain.