Contamination of pastures by polycyclic aromatic hydrocarbons (PAHs) in the vicinity of a highway

To assess PAH contamination pastures, grass and soil samples have been collected from 10 m (d1), 50 m (d2), and 150 m (d3) perpendicular to a French highway (70,000 vehicles per day) and at a control site in a rural area away from nearby contaminating sources. Total PAH concentration ranges from 767 ng/g dry weight to 3989 ng/g dry weight, according to the matrix and the distance from the highway. Distance is not a significant factor for PAH deposition on grass, while in soil it has an effect between d1 and d2 or d3. The total PAH concentration in highway samples is 8 times higher than in control site samples for grass and 7 to 4 times higher for soil. Fluoranthene, pyrene, and phenanthrene are the major PAHs in grass samples at the control site and the highway, but the concentrations are about 5 times higher near the highway. In soil samples collected near the highway, the values of concentrations between all compounds are not statistically different. PAH deposition on grass is linked to the physicochemical properties of the compounds, which lead to a specific distribution of each molecule (according to their volatility and the number of aromatic rings) while no specific behavior is revealed in soil.     

Speciation in the parthenogenetic oribatid mite genus Tectocepheus (Acari, Oribatida) as indicated by molecular phylogeny

Despite the lack of universal concepts for species and speciation, both sexual and asexual organisms are expected to diversify into discrete genotypic and morphological clusters. Species-rich clusters of parthenogenetic oribatid mites likely evolved in the absence of sexual reproduction. We used nucleotide sequences of the large and small rDNA genes (18S and 28S) and the coding genes for heat shock protein 82 (hsp82) and elongation factor-1 alpha (ef-1α) for phylogenetic analyses of three morphotypes of the parthenogenetic oribatid mite genus Tectocepheus. DNA sequence divergences of the different morphotypes were similar to those of sexual species in other organisms. Maximum likelihood analyses of single genes and combined data sets were largely congruent in reconstructing the phylogeny of the Tectocepheus species. The results suggest that the different morphotypes of Tectocepheus indeed evolved in the absence of sexual reproduction, and that Tectocepheus minor, Tectocepheus velatus and Tectocepheus sarekensis are best considered distinct species. Further, the results suggest that 18S rDNA, hsp82 and ef-1α are powerful markers for resolving phylogenetic relationships of oribatid mites. Saturation plots indicated that the D3-region of 28S is much more saturated than all other examined genes. This indicates that the D3-region is unsuitable for resolving ancient splits in oribatid mites.     

Bacterial community structure in lake sediments of microcosms contaminated with nonylphenol

The impact of nonylphenol, an estrogenic degradation product of alkylphenol polyethoxylates, on the bacterial community structure in contaminated sediments of aquatic microcosms was investigated over a period of 20 weeks using a 16S rDNA-based molecular phylogenetic approach. All microcosms showeda strong seasonal fluctuation of the dominant as well as the active bacterial microflora independent of their degree of contamination with nonylphenol. These changes were correlated with the dynamic of the total organic carbon content (TOC), ranging from 4–39 g/kg sediment dry weight and the redox potential in the sediment. Even at the highest observed nonylphenol concentration (3.4 mg/kg sediment dry weight) the bacterial community structure was mostly unchanged.     

Residue analysis of tetracyclines and their metabolites in eggs and in the environment by HPLC coupled with a microbiological assay and tandem mass spectrometry

Tetracyclines are widely used in farm animals. This can cause drug residues in products of animal origin and, after excretion of these substances, in animal slurry and in soil fertilized with that slurry. In this paper, we present a method based on a microbiological assay coupled with HPLC for the detection of oxytetracycline, tetracycline, and chlortetracycline in eggs. After a simple liquid extraction of the samples and HPLC separation, fractions were collected on microtiter plates, and the tetracyclines were analyzed using the Staphylococcus aureus assay. This method was able to identify residues of tetracyclines in eggs at a level set by regulatory agencies (i.e., 200 microg/kg). In addition, it was shown that the described microbiological method can be used as a screening assay for the detection of tetracyclines and possible biologically active metabolites in animal slurry and soil samples. Employing the same extraction procedure, it was demonstrated that LC-MS-MS allowed the quantification of 20-400 microg/kg in eggs with recoveries ranging from 71 to 109% and RSDs of 3-15%.     

The impact of environmental change on the intensity and spatial pattern of water erosion in a semi-arid mountainous Andean environment

Aerial photographs taken in 1976 and 1989 and a field survey in 1999 showed that land use in a 900-ha catchment in the southern part of the Ecuadorian Andes is highly dynamic. Over 23 years, ca. 83 ha of arable land was abandoned and ca. 70 ha was taken into agricultural production. Changes in land use were not spatially homogeneous. Parcels on unstable geologic formations and close to village centres were preferably set-aside. Land taken into cultivation was preferably located on gently sloping areas close to newly built sites and arterial roads. The area with bush vegetation increased by regeneration of natural vegetation on fields set-aside in the late 1970s and early 1980s. There was a complex interaction between water erosion and environmental change in the study area. Land taken into production was levelled for furrow irrigation: this led to a net reduction in the area susceptible to water erosion. However, one quarter of the area affected only by sheet and rill erosion 23 years ago has since become incised by deep gullies. This increase in gully density was related to inadequate construction and management of irrigation infrastructure, rather than to change in vegetation cover and/or soil erodibility caused by agricultural practices. This factor is often overlooked in studies of the effects of environmental change on geomorphologic processes.     

Dietary anthocyanin-rich tart cherry extract inhibits intestinal tumorigenesis in APC(Min) mice fed suboptimal levels of sulindac

A promising approach for cancer chemoprevention might be a combination therapy utilizing dietary phytochemicals and anticarcinogenic pharmaceuticals at a suboptimal dosage to minimize any potential adverse side effects. To test this hypothesis, various dosages of anthocyanin-rich tart cherry extract were fed in combination with suboptimal levels of the nonsteroidal anti-inflammatory drug sulindac to APCMin mice for 19 weeks. By the end of the feeding period, fewer mice that were fed the anthocyanin-rich extract in combination with sulindac lost more than 10% of body weight than mice fed sulindac alone. Mice that were fed anthocyanin-rich extract (at any dose) in combination with sulindac had fewer tumors and a smaller total tumor burden (total tumor area per mouse) in the small intestine when compared to mice fed sulindac alone. These results suggest that a dietary combination of tart cherry anthocyanins and sulindac is more protective against colon cancer than sulindac alone.     

Suitability of plant physiological methods to estimate the transpiration of agricultural crops

Transpiration is the main part of the water balance in the system soil-plant during the vegetation period. Its determination or calculation is essential for modeling of soil moisture content or solute transport. Transpiration is difficult to quantify because it is influenced by the atmosphere, the soil, and the plants. This paper describes the potential and limitations of plant physiological methods (sap flow, gas exchange, leaf water potential) to estimate the transpiration. A weighable lysimeter was used as reference method. Results are shown for corn [Zea mays L.] and rape [Brassica napus L.]) for the years 1998 and 1999. At days without rain the diurnal transpiration rates, determined by the plant physiological methods and by the lysimeter differ by less than 12%. The results demonstrate that the plant physiological methods applied are important for an understanding of the complex transpiration process. Limitations lie in the difficulties in up-scaling, and the impossibility of measurements of the absolute actual transpiration rates of agricultural crops for longer periods like months or years.