Comparing willingness to pay for improved drinking-water quality using stated preference methods in rural and urban Kenya
<i>Background</i>. Access to safe drinking water has been on the global agenda for decades. The key to safe drinking water is found in household water treatment and safe storage systems. <BR/>
<i>Objective</i>. In this study, we assessed rural and urban household demand for a new gravity-driven membrane (GDM) drinking-water filter.<BR/>
<i>Methods</i>. A choice experiment (CE) was used to assess the value attached to the characteristics of a new GDM filter before marketing in urban and rural Kenya. The CE was followed by a contingent valuation (CV) question. Differences in willingness to pay (WTP) for the same filter design were tested between methods, as well as urban and rural samples.<BR/>
<i>Results</i>. The CV follow-up approach produces more conservative and statistically more efficient WTP values than the CE, with only limited indications of anchoring. The effect of the new filter technology on children with diarrhea is among the most important drivers behind choice behavior and WTP in both areas. The urban sample is willing to pay more in absolute terms than the rural sample irrespective of the valuation method. Rural households are more price sensitive, and willing to pay more in relative terms compared with disposable household income.<BR/>
<i>Conclusion</i>. A differentiated marketing strategy across rural and urban areas is expected to increase uptake and diffusion of the new filter technology.
Metabolism of a nonylphenol isomer by <I>Sphingomonas</I> sp. strain TTNP3
For elucidation of the metabolism of the endocrine disruptor nonylphenol by <I>Sphingomonas</I> sp. strain TTNP3, the degradation of an isomer of nonylphenol, 4(2′,6′-dimethyl-2′-heptyl)-phenol, has been studied. As in the case of 4(3′,5′-dimethyl-3′-heptyl)-phenol, the metabolism of this nonylphenol isomer leads to the formation of the NIH-shifted product 2(2′,6′-dimethyl-2′-heptyl)-1,4-benzenediol (NIH: National Institute of Health), but also to the alkoxy derivative 4(2′,6′-dimethylheptan-2′-yloxy)phenol as additional metabolite. To the best of our knowledge, this is the first report describing the formation of alkoxyphenol as a degradation product of nonylphenol. Additionally, these results provide for the first time evidence for slight differences in the biodegradation of the isomers of nonylphenol.
Direct male-male competition can facilitate invasion of new colour types in Lake Victoria cichlids
The possibility that disruptive sexual selection alone can cause sympatric speciation is currently a subject of much debate. The initial difficulty for new and rare ornament phenotypes to invade a population, and the stabilisation of the resulting polymorphism in trait and preference make this hypothesis problematic. Recent theoretical work indicates that the invasion is facilitated if males with the new phenotype have an initial advantage in male-male competition. We studied a pair of sympatric incipient species of cichlids from Lake Victoria, in which the red (<I>Pundamilia nyererei</I>) and blue males (<I>P. pundamilia</I>) vigorously defend territories. Other studies suggested that red phenotypes may have repeatedly invaded blue populations in independent episodes of speciation. We hypothesised that red coloration confers an advantage in male-male competition, assisting red phenotypes to invade. To test this hypothesis, we staged contests between red and blue males from a population where the phenotypes are interbreeding morphs or incipient species. We staged contests under both white and green light condition. Green light effectively masks the difference between red and blue coloration. Red males dominated blue males under white light, but their competitive advantage was significantly diminished under green light. Contests were shorter when colour differences were visible. Experience of blue males with red males did not affect the outcome of a contest. The advantage of red over blue in combats may assist the red phenotype to invade blue populations. The apparently stable co-existence of red and blue incipient species in many populations of Lake Victoria cichlids is discussed.
Chemical composition of surgical smoke produced by electrocautery, harmonic scalpel and argon beaming - a short study
<I>Background:</I> The inhalation of aerosols during electrosurgery is part of daily surgical life. This study analyses the toxic and cancerogenic components of the aerosols.<BR/><I>Methods:</I> Electrocautery, harmonic scalpel and argon beaming were utilised in a pig model. The collected aerosols were analysed by gas chromatography coupled with mass spectrometry for acrylamide, aldehydes and ketones, volatile and semivolatile organic compounds, and polycyclic aromatic hydrocarbons.<BR/><I>Results:</I> Surgical plume of all instruments comprehends toxic components including e.g. acrylamide, acetaldehyde, formaldehyde, and benzene. Composition and toxicity varies from applied technique, energy, and processed tissue. High temperature induces more toxic aerosols. Offtake devices reduce toxic inhalations.<BR/><I>Conclusions:</I> Surgical smoke contains toxic, partly cancerogenic compounds. Concentrations estimated for daily routine are probably below relevant health risk. Nevertheless, the exposition to surgical "smog" should be minimised at any time using offtake devices. Further examinations during clinical practice are necessary.
Life history, ecology and the biogeography of strong genetic breaks among 15 species of Pacific rockfish, <I>Sebastes</I>
Strong genetic change over short spatial scales is surprising among marine species with high dispersal potential. Concordant breaks among several species signals a role for geographic barriers to dispersal. Along the coast of California, such breaks have not been seen across the biogeographic barrier of Point Conception, but other potential geographic boundaries have been surveyed less often. We tested for strong-population structure in 11 species of <I>Sebastes</I> sampled across two regions containing potential dispersal barriers, and conducted a meta-analysis including four additional species. We show two strong breaks north of Monterey Bay, spanning an oceanographic gradient and an upwelling jet. Moderate genetic structure is just as common in the north as it is in the south, across the biogeographic break at Point Conception. Gene flow is generally higher among deep-water species, but these conclusions are confounded by phylogeny. Species in the subgenus <I>Sebastosomus</I> have higher structure than those in the subgenus <I>Pteropodus</I>, despite having larvae with longer pelagic phases. Differences in settlement behavior in the face of ocean currents might help explain these differences. Across similar species across the same coastal environment, we document a wide variety of patterns in gene flow, suggesting that interaction of individual species traits such as settlement behavior with environmental factors such as oceanography can strongly impact population structure.
A lake as a microcosm: reflections on developments in aquatic ecology
In the present study, we aim at relating Forbes' remarkable paper on "The lake as a microcosm", published 125 years ago, to the present status of knowledge in our own research group. Hence, we relate the observations Forbes made to our own microcosm, Lake Krankesjön in southern Sweden, that has been intensively studied by several research groups for more than three decades. Specifically, we focus on the question: Have we made any significant progress or did Forbes and colleagues blaze the trail through the unknown wilderness and we are mainly paving that intellectual road? We conclude that lakes are more isolated than many other biomes, but have, indeed, many extensions, for example, input from the catchment, fishing and fish migration. We also conclude that irrespective of whether lakes should be viewed as microcosms or not, the paper by Forbes has been exceptionally influential and still is, especially since it touches upon almost all aspects of the lake ecosystem, from individual behaviour to food web interactions and environmental issues. Therefore, there is no doubt that even if 125 years have passed, Forbes' paper still is a source of inspiration and deserves to be read. Hence, although aquatic ecology has made considerable progress over the latest century, Forbes might be viewed as one of the major pioneers and visionary scientists of limnology.
Local adaptation and genetics of acid-stress tolerance in the moor frog, <I>Rana arvalis</I>
As potential to adapt to environmental stress can be essential for population persistence, knowledge on the genetic architecture of local adaptation is important for conservation genetics. We investigated the relative importance of additive genetic, dominance and maternal effects contributions to acid stress tolerance in two moor frog (<I>Rana arvalis</I>) populations originating from low and neutral pH habitats. Experiments with crosses obtained from artificial matings revealed that embryos from the acid origin population were more tolerant to low pH than embryos from the neutral origin population in embryonic survival rates, but not in terms of developmental stability, developmental and growth rates. Strong maternal effect and small additive genetic contributions to variation were detected in all traits in both populations. In general, dominance contributions to variance in different traits were of similar magnitude to the additive genetic effects, but dominance effects outweighed the additive genetic and maternal effects contributions to early growth in both populations. Furthermore, the expression of additive genetic variance was independent of pH treatment, suggesting little additive genetic variation in acid stress tolerance. The results suggest that although local genetic adaptation to acid stress has taken place, the current variation in acid stress tolerance in acidified populations may owe largely to non-genetic effects. However, low but significant heritabilities (h<SUP>2</SUP> ≈ 0.07-0.22) in all traits – including viability itself – under a wide range of pH conditions suggests that environmental stress created by low pH is unlikely to lower moor frog populations' ability to respond to selection in the traits studied. Nevertheless, acid conditions could lower populations' ability to respond to selection in the long run through reduction in effective population size.
Maternal investment in egg size: environment- and population-specific effects on offspring performance
Geographic variation in maternal investment in offspring size can be adaptive if differences in investment translate into improved offspring performance in the given environments. We compared two moor frog, <I>Rana arvalis</I>, populations in the laboratory to test the hypothesis that investment in large eggs in populations originating from stressful (acid) environments improves offspring performance when reared in stressful (acid) conditions. We found that large initial size (hatchling mass) had moderate to strong, environment-dependent positive effects on larval and metamorphic traits in the acidic origin population, but only weak effects in the neutral origin population. Our results suggest that interactions between environmental conditions and initial size can be important determinants of individual performance, and that investment in large eggs is adaptive in acid environments. These findings emphasize the role of maternal effects as adaptations to environmental stress.
Formation of volutin granules in <I>Corynebacterium glutamicum</I>
Volutin granules are intracellular storages of complexed inorganic polyphosphate (poly P). Histochemical staining procedures differentiate between pathogenic corynebacteria such as <em>Corynebacterum diphtheriae</em> (containing volutin) and non-pathogenic species, such as <em>C. glutamicum</em>. Here we report that strains ATCC13032 and MH20-22B of the non-pathogenic <em>C. glutamicum</em> also formed subcellular entities (18–37% of the total cell volume) that had the typical characteristics of volutin granules: (i) volutin staining, (ii) green UV fluorescence when stained with 4′,6-diamidino-2-phenylindole, (iii) electron-dense and rich in phosphorus when determined with transmission electron microscopy and X-ray microanalysis, and (iv) <sup>31</sup>P NMR poly P resonances of isolated granules dissolved in EDTA. MgCl<sub>2</sub> addition to the growth medium stimulated granule formation but did not effect expression of genes involved in poly P metabolism. Granular volutin fractions from lysed cells contained polyphosphate glucokinase as detected by SDS–PAGE/MALDI-TOF, indicating that this poly P metabolizing enzyme is present also in intact poly P granules. The results suggest that formation of volutin is a more widespread phenomenon than generally accepted.
Adaptive molecular evolution in the opsin genes of rapidly speciating cichlid species
Cichlid fish inhabit a diverse range of environments that vary in the spectral content of light available for vision. These differences should result in adaptive selective pressure on the genes involved in visual sensitivity, the opsin genes. This study examines the evidence for differential adaptive molecular evolution in East African cichlid opsin genes due to gross differences in environmental light conditions. First, we characterize the selective regime experienced by cichlid opsin genes using a likelihood ratio test format, comparing likelihood models with different constraints on the relative rates of amino acid substitution, across sites. Second, we compare turbid and clear lineages to determine if there is evidence of differences in relative rates of substitution. Third, we present evidence of functional diversification and its relationship to the photic environment among cichlid opsin genes. We report statistical evidence of positive selection in all cichlid opsin genes, except short wavelength–sensitive 1 and short wavelength–sensitive 2b. In all genes predicted to be under positive selection, except short wavelength–sensitive 2a, we find differences in selective pressure between turbid and clear lineages. Potential spectral tuning sites are variable among all cichlid opsin genes; however, patterns of substitution consistent with photic environment–driven evolution of opsin genes are observed only for short wavelength–sensitive 1 opsin genes. This study identifies a number of promising candidate-tuning sites for future study by site-directed mutagenesis. This work also begins to demonstrate the molecular evolutionary dynamics of cichlid visual sensitivity and its relationship to the photic environment.
Modeling demand for catastrophic flood risk insurance in coastal zones in Vietnam using choice experiments
In a choice experiment, households in Vietnam are offered flood insurance to mitigate increasing catastrophic flood risks due to climate change. Participants are asked to choose their most preferred insurance policy given expected future flood and mortality risks, insurance cover and associated insurance premiums. Although not affordable to everyone, there exists substantial demand for flood insurance. Insurance demand is spatially differentiated, non-linear in flood probabilities and mortality risks, and subject to significant preference heterogeneity. Since respondents are unfamiliar with the concept of flood insurance and education levels are low, choice consistency tests were conducted. These show that choice consistency depends on a combination of respondent characteristics, such as gender and education level, and experimental design characteristics.
Estimating bacterial diversity for ecological studies: methods, metrics, and assumptions
Methods to estimate microbial diversity have developed rapidly in an effort to understand the distribution and diversity of microorganisms in natural environments. For bacterial communities, the 16S rRNA gene is the phylogenetic marker gene of choice, but most studies select only a specific region of the 16S rRNA to estimate bacterial diversity. Whereas biases derived from from DNA extraction, primer choice and PCR amplification are well documented, we here address how the choice of variable region can influence a wide range of standard ecological metrics, such as species richness, phylogenetic diversity, β-diversity and rank-abundance distributions. We have used Illumina paired-end sequencing to estimate the bacterial diversity of 20 natural lakes across Switzerland derived from three trimmed variable 16S rRNA regions (V3, V4, V5). Species richness, phylogenetic diversity, community composition, β-diversity, and rank-abundance distributions differed significantly between 16S rRNA regions. Overall, patterns of diversity quantified by the V3 and V5 regions were more similar to one another than those assessed by the V4 region. Similar results were obtained when analyzing the datasets with different sequence similarity thresholds used during sequences clustering and when the same analysis was used on a reference dataset of sequences from the Greengenes database. In addition we also measured species richness from the same lake samples using ARISA Fingerprinting, but did not find a strong relationship between species richness estimated by Illumina and ARISA. We conclude that the selection of 16S rRNA region significantly influences the estimation of bacterial diversity and species distributions and that caution is warranted when comparing data from different variable regions as well as when using different sequencing techniques.
Plant uptake of phosphorus and nitrogen recycled from synthetic source-separated urine
Urine contains about 50 % of the phosphorus (P) and about 90 % of the nitrogen (N) excreted by humans and is therefore an interesting substrate for nutrient recovery. Source-separated urine can be used to precipitate struvite or, through a newly developed technology, nitrified urine fertilizer (NUF). In this study, we prepared <SUP>33</SUP>P radioisotope- and stable <SUP>15</SUP>N isotope-labeled synthetic NUF (SNUF) and struvite using synthetic urine and determined P and N uptake by greenhouse-grown ryegrass (<I>Lolium multiflorum</I> var. Gemini) fertilized with these products. The P and N in the urine-based fertilizers were as readily plant-available in a slightly acidic soil as the P and N in reference mineral fertilizers. The ryegrass crop recovered 26 % of P applied with both urine-based fertilizers and 72 and 75 % of N applied as struvite and SNUF, respectively. Thus, NUF and urine-derived struvite are valuable N and P recycling fertilizers.
Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: linking biofouling layer morphology with flux stabilization
In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m<SUP>2</SUP> h (21 ± 1 °C, 40 mbar) to 7.3 L/m<SUP>2</SUP> h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer; (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity; (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the permeate was not be reduced, possibly because some microbial species (e.g. algae) could convert CO<SUB>2</SUB> into organic substances. To further improve the removal efficiency of the organic carbon, combining carrier biofilm processes with a submerged GDM filtration system is proposed.
Pollution-induced community tolerance (PICT): towards an ecologically relevant risk assessment of chemicals in aquatic systems
1. A major challenge in environmental risk assessment of pollutants is establishing a causal relationship between field exposure and community effects that integrates both structural and functional complexity within ecosystems.<BR/>2. Pollution-induced community tolerance (PICT) is a concept that evaluates whether pollutants have exerted a selection pressure on natural communities. PICT detects whether a pollutant has eliminated sensitive species from a community and thereby increased its tolerance. PICT has the potential to link assessments of the ecological and chemical status of ecosystems by providing causal analysis for effect-based monitoring of impacted field sites.<BR/>3. Using PICT measurements and microbial community endpoints in environmental assessment schemes could give more ecological relevance to the tools that are now used in environmental risk assessment. Here, we propose practical guidance and a list of research issues that should be further considered to apply the PICT concept in the field.
Responses of net ecosystem CO<SUB>2</SUB> exchange in managed grassland to long-term CO<SUB>2</SUB> enrichment, N fertilization and plant species
The effects of elevated pCO<sub>2</sub> on net ecosystem CO<sub>2</sub> exchange were investigated in managed Lolium perenne (perennial ryegrass) and Trifolium repens (white clover) monocultures that had been exposed continuously to elevated pCO<sub>2</sub> (60 Pa) for nine growing seasons using Free Air CO<sub>2</sub> Enrichment (FACE) technology. Two levels of nitrogen (N) fertilization were applied. Midday net ecosystem CO<sub>2</sub> exchange (mNEE) and night-time ecosystem respiration (NER) were measured in three growing seasons using an open-flow chamber system. The annual net ecosystem carbon (C) input resulting from the net CO<sub>2</sub> fluxes was estimated for one growing season. In both monocultures and at both levels of N supply, elevated pCO<sub>2</sub> stimulated mNEE by up to 32%, the exact amount depending on intercepted PAR The response of mNEE to elevated pCO<sub>2</sub> was larger than that of harvestable biomass. Elevated pCO<sub>2</sub> increased NER by up to 39% in both species at both levels of N supply. NER, which was affected by mNEE of the preceding day, was higher in T. repens than in L. perenne. High N increased NER compared to low N supply. According to treatment, the annual net ecosystem C input ranged between 210 and 631 g C m<sup>-2</sup> year <sup>-1</sup> and was not significantly affected by the level of pCO<sub>2</sub>. Low N supply led to a higher net C input than high N supply. We demonstrated that at the ecosystem level, there was a long-term stimulation in the net C assimilation during daytime by elevated pCO<sub>2</sub>. However, because NER was also stimulated, net ecosystem C input was not significantly increased at elevated pCO<sub>2</sub>. The annual net ecosystem C input was primarily affected by the amount of N supplied.
Carry-over effects of embryonic acid conditions on development and growth of <I>Rana temporaria</I> tadpoles
1. Conditions experienced during the early stages of development may have carry-over effects on performance during later life. The egg laying period and embryonic development of temperate and boreal zone amphibians often coincides with peak acidity resulting from spring snow-melt, but the effects of acid conditions during embryonic stage on subsequent performance are unknown.<br/>
2. We investigated the potential carry-over effects of acidity during the embryonic stage on performance up to metamorphosis in the common frog (<I>Rana temporaria</I>) tadpoles. There were four combinations of acid (4.5) and neutral (7.5) pH treatments applied to the egg and larval stages in a factorial laboratory experiment. In addition, we studied the difference in embryonic and larval tolerance of acidity between two populations originating from circumneutral (pH 6.6) and acidic conditions (pH 4.8).<br/>
3. The effects of acid conditions during the embryonic stage were sublethal, as indicated by delayed development and reduced size. Under acid conditions, tadpoles that had been raised in neutral water as embryos at first grew more slowly than tadpoles raised under acid conditions as embryos. At metamorphosis, no effects of embryonic acidity were detectable indicating that tadpoles were able to compensate fully for the initial reduction in growth.<br/>
4. Acid conditions during the larval period had a strongly negative effect on survival, size and age at metamorphosis. The amount of food consumed was lower under acid conditions, suggesting that reduced food consumption was at least partly responsible for the negative effects.<br/>
5. Although the two populations differed in the length of larval period, there was no indication of a differential response to the treatments in any of the metamorphic traits studied.<br/>
6. These results suggest that, although moderate acid conditions during embryonic development affect growth and development negatively, this influence does not persist after conditions have returned to normal. However, even moderately acid conditions during the larval period may have a strong negative influence on survival and performance of the tadpoles.
Lethal and sublethal effects of UV-B/pH synergism on common frog embryos
Although the negative effects of ultraviolet-B (UV-B) radiation on the development of many amphibian species have been demonstrated, some species—such as the common frog (<I>Rana temporaria</I>)—seem to be tolerant of UV-B radiation. The amount of UV-B radiation received is likely to vary among populations of the same species, but little is known about geographic variation in UV-B tolerance. Similarly, although UV-B radiation can have synergistic effects with other stressors, no studies have focused on geographic variation of these effects on amphibians. We investigated the synergistic effects of UV-B radiation and low pH on hatchability and early development of <I>R. temporaria</I> embryos in a factorial laboratory experiment with animals originating from southern and northern Sweden. Newly fertilized eggs were exposed to three different UV-B treatments (no UV-B [control], 1.254 k/J/m<SUP>2</SUP> [normal] and 1.584 k/J/m<SUP>2</SUP> [26% enhanced]) and two pH treatments (4.5 [low] and 7.6 [neutral]). Ultraviolet-B radiation in combination with low pH lead to markedly (approximately 50%) reduced survival rates and increased (approximately 30%) frequency of developmental anomalies in the northern but not in the southern population. The UV-B-exposed embryos hatched at smaller size in the southern population, whereas low pH reduced hatchling size in both populations. In both populations and pH treatments, embryos in the normal UV-B treatment developed significantly faster than embryos in the enhanced or control UV-B treatments. No interaction between pH and UV-B on developmental rates or hatchling size was detected. The results demonstrate—contrary to earlier belief—that <I>R. temporaria</I> embryos are not insensitive to increased levels of UV-B radiation. The lethal effects of UV-B radiation may, however, become manifested only in combination with other stressors, such as low pH, and the effects of this synergism may differ among different populations of the same species.
Geographic variation in acid stress tolerance of the moor frog, <I>Rana arvalis</I>. I. Local adaptation
Spatially varying directional selection together with restricted gene flow among populations is expected to lead to local adaptation. One environmental factor that potentially causes strong directional selection, but is little explored in evolutionary terms, is naturally and anthropogenically induced acidity. We studied local adaptation to acidity in four Swedish populations (two originating from areas that have suffered from severe anthropogenic acidification during the 1900s and two from areas which have remained neutral due to higher buffering capacity) of the moor frog <I>Rana arvalis</I> in a laboratory experiment by investigating whether differences in acid tolerance correspond to population origin. Embryos were raised from fertilization to hatching at three different pH levels (pH 4.0, 4.25 and 7.5), corresponding to levels experienced by these populations in nature, and acid stress tolerance was measured in terms of embryonic survival, hatchling size, and age. Evidence for local adaptation in all of these traits was found, the acid origin embryos having higher survival and less impaired growth performance under acid conditions than the neutral origin embryos. Our estimated rates of divergence (0.007-0.102 haldanes) suggest a rapid adaptation process in response to anthropogenic environmental change, and that the different traits have evolved at relatively similar rates.
Degradation of estradiol and ethinyl estradiol by activated sludge and by a defined mixed culture
The aerobic degradation of the natural hormone 17-β-estradiol (E2) and the synthetic hormone 17-α-ethinyl estradiol (EE2) was investigated in batch experiments with activated sludge from a conventional and a membrane sewage treatment plant. E2 was converted to estrone (E1), the well known metabolite, and further completely transformed within 3 days. The turnover rates of E2 did not differ greatly between conventional and membrane activated sludge. EE2 was persistent in both sludges. By several transfers into fresh E2-medium an enrichment culture could be selected that used E2 as growth substrate. Further enrichment and isolation led to a defined mixed culture consisting of two strains, which were identified by a polyphasic approach as <I>Achromobacter xylosoxidans</I> and <I>Ralstonia</I> sp., respectively. The culture used E2 and E1 as growth substrates and transformed estriol (E3) and 16-α-hydroxyestrone but not the xenoestrogens bisphenol A, α-zearalenol, mestranol or EE2. The turnover rates of E2 were 0.025–0.1 μg h<sup>-1</sup> cfu<sup>-1</sup> and did not depend on the steroid concentration.
Simultaneous determination of NSO-heterocycles, homocycles and their metabolites in groundwater of tar oil contaminated sites using LC with diode array UV and fluorescence detection
For monitoring groundwater at tar oil contaminated sites a simple method of analysis was developed for the simultaneous detection of several NSO heterocyclic compounds, homocyclic compounds, mobile two- and three-cyclic PAHs and selected metabolites. The groundwater samples are enriched using SPE with polymer material at pH 4. Chromatographic separation and detection is performed by LC with diode array UV or fluorescence detection. The recoveries of 25 selected compounds were mostly between 80-110% and the detection limits were 0.4-2.4 μg/L for UV detection and for the fluorescence detectable compounds 0.4-140 ng/L. The method was successfully applied to groundwater samples from a wood preserving facility. Especially benzo(<I>b</I>)thiophene showed an increasing dominance downgradient of the source. Detection of metabolites, such as 1-hydroxyiso-, 2-hydroxyquinoline and 2-hydroxy-4-methylquinoline, 2-naphthoic acid, and 1-indanone, indicating in situ biodegradation, was confirmed by LC-ESI-MS analysis.
Metabolism of 1,8-cineole by human cytochrome P450 enzymes: identification of a new hydroxylated metabolite
Human metabolism of the monoterpene cyclic ether 1,8-cineole was investigated in vitro and in vivo. In vitro, the biotransformation of 1,8-cineole was investigated by human liver microsomes and by recombinant cytochrome P450 enzymes coexpressed with human CYP-reductase in Escherichia coli cells. Besides the already described metabolite 2α-hydroxy-1,8-cineole we found another metabolite produced at high rates. The structure was identified by a comparison of its mass spectrum and retention time with the reference compounds as 3α-hydroxy-1,8-cineole. There was a clear correlation between the concentration of the metabolites, incubation time and enzyme content, respectively. CYP3A4/5 antibody significantly inhibited the 2α- and 3α-hydroxylation catalyzed by pooled human liver microsomes. Further kinetic analysis revealed that the Michaelis-Menten <I>K</I><sub>m</sub> and <I>V</I><sub>max</sub> for oxidation of 1,8-cineole in position three were 19 μM and 64.5 nmol/min/nmol P450 for cytochrome P450 3A4, and 141 μM and 10.9 nmol/min/nmol P450 for cytochrome P450 3A5, respectively. To our knowledge, this is the first time that 3α-hydroxy-1,8-cineole is described as a human metabolite of 1,8-cineole. We confirmed these in vitro results by the investigation of human urine after the oral administration of cold medication containing 1,8-cineole. In human urine we found by GC-MS analysis the described metabolites, 2α-hydroxy-1,8-cineole and 3α-hydroxy-1,8-cineole.
Wastewater reuse and risk: definition of key objectives
Wastewater reclamation holds promise as an important water resource as the desire to develop arid regions continues to place increasing demands on finite water resources. The debate surrounding the consumption of reclaimed wastewater finds risk managers pondering the question of what types of water quality standards might be set in order to provide the proper level of safety associated with the use of reclaimed wastewater. We propose quality categories for different reuses such as irrigation or indirect aquifer recharge with different requirements towards microbial and chemical parameters. Based on recent existing guidelines and risk estimations, microbial and chemical limits for each category were compiled. Since economic calculations are very important, analytical costs are included and measurements frequency is proposed. Biological parameters have to indicate all potential pathogenic organisms including viruses, bacteria and parasites from different origins. The selected biological indicator parameters most used in rules and regulations are coliforms and <I>E coli</I>, indicating the occurrence of a former faecal contamination and the possible presence of all pathogens occurring in faeces of warm-blooded animals. In the case of wastewater reuse, biological parameters have to indicate all potential pathogens causing infection diseases and/or intoxication in all living beings including plants and animals. The large number of possible chemical parameters in relation with wastewater reclamation and reuse has to be adapted and minimized with respect to the origin of the sewage, the extent of the treatment process and the intended use. These parameters must cover a broad spectrum of toxicological and ecological risks as well as possible technical disorders. Risk assessment and risk management are also necessary.
Contribution to the detection and identification of oxidation metabolites of nonylphenol in <I>Sphingomonas</I> sp. Strain TTNP3
<I>Sphingomonas</I> sp. strain TTNP3 has been previously described as a bacterium that is capable of degrading the technical mixture of nonylphenol (NP) isomers and also the 4(3',5'-dimethyl-3'-heptyl)-phenol single isomer of NP. Until recently, 3,5-dimethyl-3-heptanol was the only reported metabolite of 4(3',5'-dimethyl-3'-heptyl)-phenol. A short time ago, the detection of an intracellular metabolite resulting from the oxidation of 4(3',5'-dimethyl-3'-heptyl)-phenol which was identified as 2(3,5-dimethyl-3-heptyl)-benzenediol has been reported. A decisive element for this identification was the occurrence of some slight differences with the two most probable metabolites i.e. 4(3',5'-dimethyl-3'-heptyl)-resorcinol and 4(3',5'-dimethyl-3'-heptyl)-catechol. These facts led us to hypothesise some NIH shift mechanisms explaining the formation of 2(3',5'-dimethyl-3'-heptyl)-benzenediol. In the present work, we describe the steps that led to the detection of these metabolites in the intracellular fraction of Sphingomonas sp. strain TTNP3. The formation of analogous intracellular metabolites resulting from the degradation of the technical mixture of NP is reported. To further elucidate these degradation products, studies were carried out with cells grown with 4(3',5'-dimethyl-3'-heptyl)-phenol as sole carbon source. The description of the syntheses of reference compounds, i.e. 4(3',5'-dimethyl-3'-heptyl)-resorcinol and 4(3',5'-dimethyl-3'-heptyl)-catechol and their comparative analyses with the intermediates of the degradation of 4(3',5'-dimethyl-3'-heptyl)-phenol are presented.
Hydrological variability in southeastern Patagonia and explosive volcanic activity in the southern Andean Cordillera during Oxygen Isotope Stage 3 and the Holocene inferred from lake sediments of Laguna Potrok Aike, Argentina
Seismic reflection studies in the maar lake Laguna Potrok Aike (51°58′ S, 70°23′ W) revealed an erosional unconformity associated with a sub-aquatic lake-level terrace at a water depth of 30m. Radiocarbon-dated, multi-proxy sediment studies of a piston core from this location indicate that the sediment below this discontinuity has an age of 45kyr BP (Oxygen Isotope Stage 3), and was deposited during an interval of high lake level. In comparison to the Holocene section, geochemical indicators of this older part of the record either point towards a different sediment source or to a different transport mechanism for Oxygen Isotope Stage 3 sediments. Holocene sedimentation started again before 6790cal. yr BP, providing a sediment record of hydrological variability until the present. Geochemical and isotopic data indicate a fluctuating lake level until 5310cal. yr BP. During the late Holocene the lake level shows a receding tendency. Nevertheless, the lake level did not drop below the 30m terrace to create another unconformity. The geochemical characterization of volcanic ashes reveals evidence for previously unknown explosive activity of the Reclús and Mt. Burney volcanoes during Oxygen Isotope Stage 3.
Scientists working closely on issues of water reuse are far from having solved all concerns related to the practice. From the very beginning of a water reuse project, scenarios must be prepared from the 'zero scenario' (no reuse) through to more complex and expensive ones (e.g. reverse osmosis for potable water treatment) to help stakeholders to select the best option for increasing available water resources, the ultimate purpose of reuse. In any case, the use of adequate tools to build scenarios is paramount. From Decision Support Systems to the simplest analytical tools, all knowledge is valuable. Detailed studies must be undertaken to identify necessary technologies, schemes and control tools. As public health concerns are normally among the main constraints for reuse any scenario will need to include detailed risk assessments. To achieve an adequate risk assessment, data pertaining to microbiological, chemical and biological factors is necessary. Unfortunately, suitable techniques and criteria are not always established by rules and regulations. However, several strong attempts have been made in some countries. Once the basic calculations were performed, a final decision whether the scheme can be implemented should be based on three phases of risk assessment; analysis, calculation and communication. This will allow fulfilling the key objectives of reuse: increasing the amount of water resources available, under an acceptable risk with a public full knowledge.
Huertas, E.; Salgot, M.; Hollender, J.; Weber, S.; Dott, W.; Khan, S.; Schäfer, A.; Messalem, R.; Bis, B.; Aharoni, A.; Chikurel, H. (2008) Key objectives for water reuse concepts, Desalination, 120 - 131
Differential decline and recovery of haplochromine trophic groups in the Mwanza Gulf of Lake Victoria
Lake Victoria had a fish fauna dominated by 500+ species of haplochromine cichlids that made up more than 80% of the fish mass. The five main trophic groups caught with bottom trawlers in the sub-littoral areas of the Mwanza Gulf were: detritivores, zooplanktivores, insectivores, molluscivores and piscivores. The detritivores (13+ species) formed the most important guild, making up 60-80% of the number of individuals, followed by the zooplanktivores (12+ species), which comprised 10-30%. In the 1980s the haplochromines from the sub-littoral and offshore areas (estimated at some 200 species) vanished almost completely. Commercial trawl fishery, the upsurge of the introduced Nile perch, and an increase of eutrophication were potential causes of this decline. In the 1990s, when Nile perch was heavily fished, a recovery of some haplochromine species was observed. We studied the decline and partial recovery of the different haplochromine trophic groups in the northern part of the Mwanza Gulf. The rate at which the trophic groups declined differed; the relatively large piscivores, insectivores and molluscivores were the first to disappear from the catches. The small detritivores and zooplanktivores declined at lower rates, especially the latter group. From the beginning of the 1990s a resurgence of both groups was observed. By 2001, the zooplanktivores had reached their previous level of abundance, but their diversity declined from more than 12 species to only three. Though four detritivorous species began being regularly caught again, they constituted only about 15% of the number of individuals, while the zooplanktivores made up more than 80%. The patterns of decline and recovery indicate that, though fishery played a role locally, predation by Nile perch and eutrophication were the main factors determining the fate of the haplochromines. However, it has so far been impossible to establish the causal relationship between the two, and the relative impact of each of these phenomena separately. The potential effects of the changed trophic dominance, and the importance of the haplochromines for the ecosystem and a sustainable fishery, are discussed.
The degradation of α-quaternary nonylphenol isomers by <I>Sphingomonas</I> sp. strain TTNP3 involves a type II <I>ipso</I>-substitution mechanism
The degradation of radiolabeled 4(3′,5′-dimethyl-3′- heptyl)-phenol [nonylphenol (NP)] was tested with resting cells of <I>Sphingomonas</I> sp. strain TTNP3. Concomitantly to the degradation of NP, a metabolite identified as hydroquinone transiently accumulated and short-chain organic acids were then produced at the expense of hydroquinone. Two other radiolabeled isomers of NP, 4(2′, 6′-dimethyl-2′-heptyl)-phenol and 4(3′,6′-dimethyl-3′-heptyl)-phenol, were synthesized. In parallel experiments, the 4(2′,6′-dimethyl-2′-heptyl)-phenol was degraded more slowly than the other isomers of NP by strain TTNP3, possibly because of effects of the side-chain structure on the kinetics of degradation. Alkylbenzenediol and alkoxyphenol derivatives identified as metabolites during previous studies were synthesized and tested as substrates. The derivatives were not degraded, which indicated that the mineralization of NP does not proceed via alkoxyphenol as the principal intermediate. The results obtained led to the elucidation of the degradation pathway of NP isomers with a quaternary α-carbon. The proposed mechanism is a type II <I>ipso</I> substitution, leading to hydroquinone and nonanol as the main metabolites and to the dead-end metabolites alkyl-benzenediol or alkoxyphenol, depending on the substitution at the α-carbon of the carbocationic intermediate formed.
Respiration rates of Eurasian perch <I>Perca fluviatilis</I> and ruffe: lower energy costs in groups
The effect of group size on the routine metabolic rate and activity of the two shoaling percids, Eurasian perch <I>Perca fluviatilis</I> and ruffe <I>Gymnocephalus cernuus</I>, was studied by using twin-flow intermittent respirometry and time-lapse video techniques. In both species, we found a clear group effect. In isolated fish, oxygen consumption was as much as twice that in groups of eight fish, with intermediate values in groups of four fish. The routine metabolic rate was highest during twilight in both species, irrespective of group size. Eurasian perch consumed more oxygen and were more active during the day than during the night, whereas the oxygen consumption and activity of ruffe were higher during the night than during the day. With increasing group size, the differences between day and night decreased and the diel cycle was less pronounced. Individual fish may benefit from the presence of conspecifics through a calming effect that reduces their energetic costs. We advise that the social behavior of a species be more thoroughly considered when planning behavioral, growth, and respiration experiments. Because bioenergetic model parameters for many species are based on data gained from isolated fish, we conclude that without considering group size the results of bioenergetic modeling may be seriously biased.
Colonization history of the Swiss Rhine basin by the bullhead (<I>Cottus gobio</I>): inference under a Bayesian spatially explicit framework
The present distribution of freshwater fish in the Alpine region has been strongly affected by colonization events occurring after the last glacial maximum (LGM), some 20 000 years ago. We use here a spatially explicit simulation framework to model and better understand their colonization dynamics in the Swiss Rhine basin. This approach is applied to the European bullhead (<I>Cottus gobio</I>), which is an ideal model organism to study fish past demographic processes since it has not been managed by humans. The molecular diversity of eight sampled populations is simulated and compared to observed data at six microsatellite loci under an approximate Bayesian computation framework to estimate the parameters of the colonization process. Our demographic estimates fit well with current knowledge about the biology of this species, but they suggest that the Swiss Rhine basin was colonized very recently, after the Younger Dryas some 6600 years ago. We discuss the implication of this result, as well as the strengths and limits of the spatially explicit approach coupled to the approximate Bayesian computation framework.
Information exchange in policy networks is usually attributed to preference similarity, influence reputation, social trust, and institutional actor roles. We suggest that political opportunity structures and transaction costs play another crucial role and estimate a rich statistical network model on tie formation in the German toxic chemicals policy domain. The results indicate that the effect of preference similarity is absorbed by institutional, relational, and social opportunity structures. Political actors choose contacts who minimize transaction costs while maximizing outreach and information. We also find that different types of information exchange operate in complementary, but not necessarily congruent, ways.
Political discourse networks and the conflict over software patents in Europe
In 2005, the European Parliament rejected the directive ‘on the patentability of computer-implemented inventions’, which had been drafted and supported by the European Commission, the Council and well-organised industrial interests, with an overwhelming majority. In this unusual case, a coalition of opponents of software patents prevailed over a strong industry-led coalition. In this article, an explanation is developed based on political discourse showing that two stable and distinct discourse coalitions can be identified and measured over time. The apparently weak coalition of software patent opponents shows typical properties of a hegemonic discourse coalition. It presents itself as being more coherent, employs a better-integrated set of frames and dominates key economic arguments, while the proponents of software patents are not as well-organised. This configuration of the discourse gave leeway for an alternative course of political action by the European Parliament. The notion of discourse coalitions and related structural features of the discourse are operationalised by drawing on social network analysis. More specifically, discourse network analysis is introduced as a new methodology for the study of policy debates. The approach is capable of measuring empirical discourses both statically and in a longitudinal way, and is compatible with the policy network approach.
Sizing up your enemy: individual predation vulnerability predicts migratory probability
Partial migration, in which a fraction of a population migrate and the rest remain resident, occurs in an extensive range of species and can have powerful ecological consequences. The question of what drives differences in individual migratory tendency is a contentious one. It has been shown that the timing of partial migration is based upon a trade-off between seasonal fluctuations in predation risk and growth potential. Phenotypic variation in either individual predation risk or growth potential should thus mediate the strength of the trade-off and ultimately predict patterns of partial migration at the individual level (i.e. which individuals migrate and which remain resident). We provide cross-population empirical support for the importance of one component of this model-individual predation risk-in predicting partial migration in wild populations of bream <em>Abramis brama</em>, a freshwater fish. Smaller, high-risk individuals migrate with a higher probability than larger, low-risk individuals, and we suggest that predation risk maintains size-dependent partial migration in this system.
Changing handwashing behaviour in southern Ethiopia: a longitudinal study on infrastructural and commitment interventions
Improved hand hygiene efficiently prevents the major killers of children under the age of five years in Ethiopia and globally, namely diarrhoeal and respiratory diseases. Effective handwashing interventions are thus in great demand. Evidence- and theory-based interventions, especially when matched to the target population's needs, are expected to perform better than common practice. To test this hypothesis, we selected two interventions drawing on a baseline questionnaire-study that applied the RANAS (Risk, Attitudes, Norms, Abilities, Self-regulation) approach and focused on the primary caregivers of households in four rural, water-scarce kebeles (smallest administrative units of Ethiopia) in southern Ethiopia (<I>N</I>=462). The two interventions were tested in combination with a standard education intervention in a quasi-experiment, as follows: kebele 1, education intervention, namely an f-diagram exercise, (<I>n</I>=23); kebele 2, education intervention and public-commitment (<I>n</I>=122); kebele 3, education intervention and tippy-tap-promotion (i.e. handwashing-station-promotion; <I>n</I>=150); kebele 4, education intervention, public-commitment and tippy-tap-promotion (<I>n</I>=113). In kebeles 3 and 4, nearly 100% of the households followed the promotion and invested material and time to construct for themselves a tippy-tap. Three months after intervention termination, the tippy-taps were in use with water and soap being present in up to 83% of the households (kebele 4). Pre-post data analysis on self-reported handwashing revealed that the population-tailored interventions, and especially the tippy-tap-promotion, performed better than the standard education intervention. Tendencies in observed behaviour and a recently developed implicit self-measure pointed to similar results. Changing people's hand hygiene is known to be a challenging task, especially in a water-scarce environment. The present project suggests not only to apply theory and evidence to improve handwashing interventions' effectiveness, but also emphasizes the relevance of tailoring interventions to the target population.