The Elbe flood in August 2002--occurrence of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/F) and dioxin-like PCB in suspended particulate matter (SPM), sediment and fish.

As a result of extreme precipitation in August 2002 major flooding occurred in the catchment area of the rivers Elbe, Vltava (Moldau) and Mulde. Pollutants from industrial sites and from municipal sewage treatment works (STW) entered the Elbe and led to a serious pollution problem in the river. PCDD/F concentrations (in pg WHO-TEQ/g dw) in SPM ranged from 7-150, in sediments from 3-140; the "safe sediment value" of 20 was exceeded in 46% of the samples. 24 eels showed a wide concentration variation for these contaminants. The WHO-PCDD/F+PCB-TEQ values lay in the range from 11-56 pg/g ww, whereby the WHO-PCB-TEQ values were several times higher than the WHO-PCDD/F-TEQ values. The maximum permitted value of 4 pg WHO-PCDD/F/g ww (EU Directive No. 2375/2001) was reached or exceeded in 54% of the individuals. A statistical analysis using data from SPM and sediment samples showed that in the Czech river section the flooding activated a contamination source in the vicinity of the Spolana works. The influence of the tributary Mulde could be clearly demonstrated. Only a major clean-up of the contaminated sites in Bitterfeld can lead to a mid to long term improvement in respect of PCDD/F and dioxin-like PCB input into the Elbe.     

Compressed Sensing and Redundant Dictionaries

This paper extends the concept of compressed sensing to signals that are not sparse in an orthonormal basis but rather in a redundant dictionary. It is shown that a matrix, which is a composition of a random matrix of certain type and a deterministic dictionary, has small restricted isometry constants. Thus, signals that are sparse with respect to the dictionary can be recovered via basis pursuit (BP) from a small number of random measurements. Further, thresholding is investigated as recovery algorithm for compressed sensing, and conditions are provided that guarantee reconstruction with high probability. The different schemes are compared by numerical experiments.     

Blocked and overshadowed stimuli are weakened in their ability to serve as blockers and second-order reinforcers in Pavlovian fear conditioning

The ability of a blocked or overshadowed conditioned stimulus (CS) to serve as (a) blocker or (b) a 2nd-order reinforcer in Pavlovian fear conditioning was tested in 152 albino rats. CS-evoked suppression of barpressing for food was the index of conditioned fear. Experiments 1 and 2 showed that an overshadowed CS was weakened in its ability to serve as a blocker. In Experiment 2, a blocked CS was similarly weakened. Experiment 3 showed that an overshadowed and blocked CS was weakened in its ability to serve as a 2nd-order reinforcer. Experiments 4 and 5 failed to restore the blocking ability of blocked (Experiment 4) or overshadowed (Experiment 5) CSs by extinguishing the CSs that had blocked or overshadowed them. Results favor a learning-deficit view of blocking and overshadowing.     

Microbiological oxidation of 2-methylbutanol of differing enantiomeric ratios by Gluconobacter species

 2-Methylbutanoic acid, an aroma compound of high economic interest, was synthesised using Gluconobacter species for bioconversion. The main focus was on enantioselective effects during metabolism. A preference for the (S)-enantiomer was observed when the microorganisms were fed with 2-methylbutanol of known enantiomeric ratios. Received: 15 December 1997     

Development of Genetic Modification Tools for Hanseniaspora uvarum

Apiculate yeasts belonging to the genus Hanseniaspora are commonly isolated from viticultural settings and often dominate the initial stages of grape must fermentations. Although considered spoilage yeasts, they are now increasingly becoming the focus of research, with several whole-genome sequencing studies published in recent years. However, tools for their molecular genetic manipulation are still lacking. Here, we report the development of a tool for the genetic modification of Hanseniaspora uvarum. This was employed for the disruption of the HuATF1 gene, which encodes a putative alcohol acetyltransferase involved in acetate ester formation. We generated a synthetic marker gene consisting of the HuTEF1 promoter controlling a hygromycin resistance open reading frame (ORF). This new marker gene was used in disruption cassettes containing long-flanking (1000 bp) homology regions to the target locus. By increasing the antibiotic concentration, transformants were obtained in which both alleles of the putative HuATF1 gene were deleted in a diploid H. uvarum strain. Phenotypic characterisation including fermentation in Müller-Thurgau must showed that the null mutant produced significantly less acetate ester, particularly ethyl acetate. This study marks the first steps in the development of gene modification tools and paves the road for functional gene analyses of this yeast.     

Tolerance does not develop to the decrease in nicotine self-administration produced by repeated bupropion administration.

The atypical antidepressant bupropion has been shown to be an efficacious smoking cessation agent; however, its therapeutic mechanism of action is unknown. To further understand the mechanism by which bupropion reduces smoking, the present study determined the effect of repeated bupropion pretreatment on nicotine self-administration or sucrose-maintained responding. Rats were trained to self-administer intravenous nicotine (0.02 mg/kg/infusion; Experiment 1) or to respond for sucrose pellets (45 mg each; Experiment 2) on a fixed-ratio 5 schedule. Once rats reached stable responding, bupropion (70 mg/kg, subcutaneously) or vehicle was injected 15 min before the session for 14 consecutive sessions. Bupropion acutely decreased both nicotine self-administration and sucrose-maintained responding by approximately 60%-70%. With repeated bupropion pretreatment, however, responding for nicotine decreased completely. In contrast, the bupropion-induced decrease in responding for sucrose following acute administration did not change significantly with repeated bupropion administration. These results suggest that bupropion acquired some specificity with repeated use, decreasing the intake of nicotine and producing an extinction-like pattern in nicotine self-administration. Thus the present results parallel human clinical studies with bupropion demonstrating its smoking cessation properties following repeated treatment. These results indicate that the rat nicotine self-administration paradigm is a useful animal model for assessing smoking cessation pharmacotherapies.