Feinstrukturveränderungen bei der Sol ⇌ Gel-Transformation des Cytoplasmas

The Science of Nature -     

Enantiomeric separation of metolachlor and its metabolites using LC-MS and CZE

The stereoisomers of metolachlor and its two polar metabolites [ethane sulfonic acid (ESA) and oxanilic acid (OXA)] were separated using liquid chromatography-mass spectrometry (LC-MS) and capillary zone electrophoresis (CZE), respectively. The separation of metolachlor enantiomers was achieved using a LC-MS equipped with a chiral stationary phase based on cellulose tris(3,5-dimethylphenyl carbamate) and an atmospheric pressure chemical ionization source operated under positive ion mode. The enantiomers of ESA and OXA were separated using CZE with gamma-cyclodextrin (gamma-CD) as chiral selector. Various CZE conditions were investigated to achieve the best resolution of the ESA and OXA enantiomers. The optimum background CZE electrolyte was found to consist of borate buffer (pH=9) containing 20% methanol (v/v) and 2.5% gamma-CD (w/v). Maximum resolution of ESA and OXA enantiomers was achieved using a capillary temperature of 15 degrees C and applied voltage of 30 kV. The applicability of the LC-MS and CZE methods was demonstrated successfully on the enantiomeric analysis of metolachlor and its metabolites in samples from a soil and water degradation study that was set up to probe the stereoselectivity of metolachlor biodegradation. These techniques allow the enantiomeric ratios of the target analytes to be followed over time during the degradation process and thus will prove useful in determining the role of chirality in pesticide degradation and metabolite formation.     

Development of the high spatial resolution EMICAT2000 emission model for air pollutants from the north-eastern Iberian Peninsula (Catalonia, Spain)

Ozone (O(3)) pollution episodes take place in Catalonia (NE of the Iberian Peninsula), mainly during summertime. The complex O(3) behaviour could be understood by using a Chemical Transport Model (CTM). Emission inventories provide the spatial and temporal emissions distribution of the O(3) precursors and other pollutants required by this approach. We developed the EMICAT2000 model with high spatial (cells of 1 km(2)) and temporal (1h) resolutions, to estimate the emissions during the year 2000 from Catalonia. Total annual emissions were 107 kt yr(-1) of NO(x), 137 kt yr(-1) of NMVOC, 267 kt yr(-1) of CO, 65 kt yr(-1) of SO(2), 24 kt yr(-1) of TSP and 32,175 kt yr(-1) of equivalent CO(2). Main NO(x) sources are on-road traffic (58%) and industries (38%). Main NMVOC sources are on-road traffic (36%), vegetation (34%) and use of solvents (13%). Speciation was established according to the Carbon Bond IV mechanism. EMICAT2000 generates directly the data files required for the third generation CTM Models-3/CMAQ.     

Aristolochic acid content of South-East Asian troidine swallowtails (Lepidoptera: Papilionidae) and of Aristolochia plant species (Aristolochiaceae)

Summary. Analysis of South-East Asian troidine swallowtails revealed high variability in the content of aristolochic acids among individuals. The presence or absence of these compounds depends on the Aristolochia species available as food plant for the larvae. Only one plant species (Aristolochia philippinensis) contained a high concentration of aristolochic acids, while other species from various localities contained none or only marginal amounts. Whether aristolochic acids have a distinct function in chemical defense of these swallowtails is still an open question. Received 11 December 2000; accepted 4 August 2001.     

Individual differences in the mechanisms underlying the onset and maintenance of paternal behavior and the inhibition of infanticide in the monogamous biparental California mouse,Peromyscus californicus

Virgin male Peromyscus californicus tend to behave infanticidally or nonparentally towards pups, whereas virtually all males exhibit parental behavior following birth of their own young. Most males (65–75%) living with their pregnant partner attacked or ignored unfamiliar pups and did not become parental (behave parentally) prior to birth of their young. However, a significant minority of males (34%) living with their partner became parental after just 24 h of postcopulatory cohabitation with the female and remained parental throughout their mate's pregnancy. Males that were infanticidal before the birth of their young became parental only after their young were born. The presence of the mother was necessary for the postpartum maintenance of paternal behavior and the inhibition of infanticide in males that were infanticidal prepartum. In contrast, males that were paternal prior to birth of their young continued to be paternal after birth, even in the absence of postpartum contact with the mother. Thus, different mechanisms are involved in the inhibition of infanticide and the onset and maintenance of paternal behavior. Correspondence to: D.J. Gubernick     

Predicting change in fish mercury concentrations following reservoir impoundment

Fish mercury concentrations frequently increase after impoundment of a reservoir. Soil flooding releases organic matter and nutrients, providing food to bacterial communities that methylate inorganic mercury. Methylation and bioaccumulation are the primary pathways for mercury accumulation in fish. We investigated if changes in fish mercury concentrations could be predicted from the change in reservoir size. Data for three fish species, northern pike (Esox lucius), walleye (Stizostedion vitreum), and lake whitefish (Coregonus clupeaformis) from reservoirs in northern Manitoba and northern Quebec were used to evaluate four simple models of change in mercury with change in flooded area. For three additional fish species, all primary carnivores, the preferred model consisted of a single exponential enrichment term. This model successfully predicted two cases not used in model development-one with a large change in area and one with a small change in area. Models with good predictive skill can be developed when the underlying dynamics are known.     

Case study: Voluntary agreements in environmental management at formosa plastics

Three agreements addressing environmental and safety performance, zero discharge of wastewater and sustainable development have been signed between Formosa Plastics Corporation, Texas (Formosa Plastics), and its former adversaries. The key element of the agreements is the improvement of the affected community. These agreements go beyond public information and beyond procedures for public participation. They have led to meaningful public participation and partnership and are unique in this respect. The following article explores the setup and results of each agreement. The initial agreement, the Blackburn-Formosa Agreement, signed in 1992, set the stage for subsequent partnerships. The Wilson-Formosa Zero Discharge Agreement followed in 1994. Finally, the Sustainable Development Agreement was signed by Jim Blackburn, Diane Wilson, and Formosa Plastics in late 1997. These agreements have proven very successful in avoiding disputes and helping improve company performance in environmental and safety issues. In many respects, these agreements offer a model for others in working with an affected community.