Cytoskeletal elements in the bacterium Mycoplasma pneumoniae

Mycoplasma pneumoniae is a pathogenic eubacterium lacking a cell wall. Three decades ago, a "rod", an intracellular cytoskeletal structure, was discovered that was assumed to define and stabilize the elongated cell shape. Later, by treatment with detergent, a "Triton shell" (i.e. a fraction of detergent-insoluble cell material) could be obtained, believed to contain additional cytoskeletal elements. Now, by application of a modified Triton X-100 treatment, we are able to demonstrate that M. pneumoniae possesses a cytoskeleton consisting of a blade-like rod and a peripheral lining located close to the inner face of the cytoplasmic membrane, exhibiting features of a highly regular network. Attached "stalks" may support the cytoplasmic membrane. The rod was connected to the cell periphery by "spokes" and showed a defined ultrastructure. Its proximal end was found to be attached to a wheel-like complex. Fibrils extended from the proximal end of the rod into the cytoplasm.     

Regional variation of selected polyaromatic and chlorinated hydrocarbons over the South Island of New Zealand, as indicated by their content in Pinus radiata needles

We analysed needles of Pinus radiata along three transects through the South Island of New Zealand for chlorinated hydrocarbons ( alpha- and gamma-HCH, HCB and PCB) and PAH (fluoranthene, 3,4-benzopyrene, benzo(ghi)perylene and indenopyrene). At rural sites we also collected samples of moss (Wijkia extenuata) and lichens (Usnea sp.) in order to compare the pollutant concentrations within these plants. A principal component analysis confirmed findings from moss and snow studies in Europe that the PAH concentrations vary regionally in the same way. The pattern of the principal component loadings of the chlorinated hydrocarbons reflects their heterogeneous immission and their different chemodynamics. The regional pattern indicates an increase of gamma-HCH from remote areas to those used intensively for agriculture and gardening, followed by a decrease towards the inner city of Christchurch. In contrast, PCB and PAH show their highest levels of contamination in the city. The regional distribution of PAH in Christchurch correlates well with traffic density, and particularly with the pattern of smoke from domestic fires. Our study demonstrates that needles of P. radiata can be better monitors of atmospheric pollution in New Zealand than mosses or lichens.     

Copper bioavailability and extractability as related to chemical properties of contaminated soils from a vine-growing area

Vineyard soils have been contaminated by Cu as a consequence of the long-term use of Cu salts as fungicides against mildew. This work aimed at identifying which soil parameters were the best related to Cu bioavailability, as assessed by measuring the concentrations of Cu in shoots and roots of tomato cropped (in lab conditions) over a range of 29 (24 calcareous and five acidic) Cu-contaminated topsoils from a vine-growing area (22-398 mg Cu kg(-1)). Copper concentrations in tomato shoots remained in the adequate range and were independent of soil properties and soil Cu content. Conversely, strong, positive correlations were found between root Cu concentration, total soil Cu, EDTA- or K-pyrophosphate-extractable Cu and organic C contents in the 24 calcareous soils, suggesting a prominent role of organic matter in the retention and bioavailability of Cu. Such relations were not observed when including the five acidic soils in the investigated population, suggesting a major pH effect. Root Cu concentration appeared as a much more sensitive indicator of soil Cu bioavailability than shoot Cu concentration. Simple extractions routinely used in soil testing procedures (total and EDTA-extractable Cu) were adequate indicators of Cu bioavailability for the investigated calcareous soils, but not when different soil types were considered (e.g. acidic versus calcareous soils).     

Umweltdatenbanken bei STN International — ihre Nutzung in der Praxis

Der Beitrag umfa?t eine übersicht über die Entwicklung wesentlicher Segmente des in Deutschland und international zug?nglichen Angebots an Umweltdatenbanken. Anschlie?end werden wichtige Umweltdatenbanken im Angebot von STN International dargestellt. Anhand ausgew?hlter Beispiele aus der Recherchepraxis werden schlie?lich Ablauf (Stufen der Vorbereitung, Durchführung und Nachbereitung) sowie Ergebnisse der Online-Recherche in wichtigen STN-Umweltdatenbanken dargestellt.     

Grundwassergefährdung durch Holzschutzmittel

Goal and Background

As a consequence of the implementation of EU Directive 98/8/EC into national law in June 2002, all biocidal products will be subjected to an authorization procedure. Condition for issue of an authorization is that the product or its residues do not exert unacceptable effects on human and animal health or on surface water and groundwater. Hence, among other issues, impact of wood preservatives on groundwater is to be assessed. Focus is particularly on impregnating plants with open-air storage sites for treated wood.

Methods

Based on already in-use versions of the leaching model PELMO, an advanced version (MC-PELMO 3.0) was developed with a specific focus on estimating groundwater contamination under storage sites at wood preserving facilities in Germany. The model processes twenty-two different leaching scenarios that were derived from twelve characteristic soil profiles representing pedological regions in Germany along with recorded meteorological data from nine weather stations. These data are related to geographic distribution of industrial wood preserving activity. The model calculates statistic probabilities of concentrations of wood preservatives in seepage water beneath timber storage sites of regions to be selected by the user.

Results and Discussion

The reports provided by MC-PELMO 3.0 include mean average concentrations, 55 to 99 percentiles, and single maximum concentrations for each of the scenarios. the results can be related to the total area of Germany, its forest area or to the density of preversation activity in various regions. Beside concentrations of the parent compounds, those of degradation products may be calculated for the seepage water.

Conclusion

The described model is a particularly useful tool for comparative assertion of various wood preservative products under aspects of the exposure of groundwater resources. Comparative assertion is a new element within EU-chemicals policy, for the first time materialized in the biocidal products directive 98/8/EC. Furthermore, the results of model calculations identify vulnerable regions in Germany for which appropriate risk management measures have to be taken in order to protect groundwater from contamination.     

Deoxyribonucleotide synthesis and the emergence of DNA in molecular evolution

DNA replication requires monomeric deoxyribonucleotides, which cannot be regarded as primary products of organic syntheses on a primitive earth. However, the present biosynthetic pathway — reductive elimination of the 2′-OH group from ribonucleotides, catalyzed by ribonucleotide reductases and thioredoxins — suggests an early, polyphyletic combination of protein-nucleotide interactions and metal catalysis. That key process had to precede the upcome of RNA-DNA dualism on the way from RNA-protein protocells to true organisms.