| 1. |
- Nilsson, R. Henrik, 1976, et al.
(författare)
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An open source chimera checker for the fungal ITS region
- 2010
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-0998 .- 1755-098X. ; 10:6, s. 1076-1081
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Tidskriftsartikel (refereegranskat)abstract
- The internal transcribed spacer (ITS) region of the nuclear ribosomal repeat unit holds a central position in the pursuit of the taxonomic affiliation of fungi recovered through environmental sampling. Newly generated fungal ITS sequences are typically compared against the International Nucleotide Sequence Databases for a species or genus name using the sequence similarity software suite blast. Such searches are not without complications however, and one of them is the presence of chimeric entries among the query or reference sequences. Chimeras are artificial sequences, generated unintentionally during the polymerase chain reaction step, that feature sequence data from two (or possibly more) distinct species. Available software solutions for chimera control do not readily target the fungal ITS region, but the present study introduces a blast-based open source software package (available at http://www.emerencia.org/chimerachecker.html) to examine newly generated fungal ITS sequences for the presence of potentially chimeric elements in batch mode. We used the software package on a random set of 12 300 environmental fungal ITS sequences in the public sequence databases and found 1.5% of the entries to be chimeric at the ordinal level after manual verification of the results. The proportion of chimeras in the sequence databases can be hypothesized to increase as emerging sequencing technologies drawing from pooled DNA samples are becoming important tools in molecular ecology research.
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| 2. |
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| 3. |
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| 4. |
- Backhaus, Thomas, 1967, et al.
(författare)
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SINGLE-SUBSTANCE AND MIXTURE TOXICITY OF FIVE PHARMACEUTICALS AND PERSONAL CARE PRODUCTS TO MARINE PERIPHYTON COMMUNITIES
- 2011
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268. ; 30:9, s. 2030-2040
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Tidskriftsartikel (refereegranskat)abstract
- The single-substance and mixture toxicity of five pharmaceuticals and personal care products (fluoxetine, propranolol, triclosan, zinc-pyrithione, and clotrimazole) to marine microalgal communities (periphyton) was investigated. All compounds proved to be toxic, with median effective concentration values (EC50s) between 1,800 nmol/L (triclosan) and 7.2 nmol/L (Zn-pyrithione). With an EC50 of 356 nmol/L, the toxicity of the mixture falls into this span, indicating the absence of strong synergisms or antagonisms. In fact, a comparison with mixture toxicity predictions by the classical mixture concepts of concentration addition and independent action showed a good predictability in the upper effect range. However, the mixture provoked stimulating effects (hormesis) in the lower effect range, hampering the application of either concept. An independent repetition of the mixture experiment resulted in a principally similar concentration-response curve, again with clear hormesis effects in the lower range of test concentrations. However, the curve was shifted toward higher effect concentrations (EC50 1,070 nmol/L), which likely is due to changes in the initial species composition. Clear mixture effects were observed even when all five components were present only at their individual no-observed-effect concentrations (NOECs). These results show that, even with respect to mixtures of chemically and functionally dissimilar compounds, such as the five pharmaceuticals and personal care products investigated, environmental quality standards must take possible mixture effects from low-effect concentrations of individual compounds into consideration. Environ. Toxicol. Chem. 2011;30:2030-2040. (C) 2011 SETAC
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| 5. |
- Brosché, Sara, 1978
(författare)
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Effects of pharmaceuticals on natural microbial communities: Tolerance development, mixture toxicity and synergistic interactions
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to our extensive use of pharmaceuticals, low concentrations (picomol-nanomol/L) end up in the aquatic environment. Antibiotics comprise a group of pharmaceuticals specifically designed to disrupt microbial biochemical processes, and might therefore in particular have detrimental effects on microbial communities in the environment. However, current environmental risk assessment strategies of pharmaceuticals do not necessarily suffice for protecting environmental microbes. Therefore, the ecotoxicity of pharmaceuticals were assessed on natural bacterial communities to provide ecologically more realistic data and to improve the knowledge about their environmental hazard. Paper I, III and IV in the thesis focussed on the effects of antibiotics. It was shown that in particular chlortetracycline, but potentially also ciprofloxacin, is clearly toxic already at concentrations currently detected in the environment, hence posing an environmental risk to environmental bacteria. In paper II, attached microbial communities were exposed to 5 pharmaceuticals and personal-care products (PPCPs) (fluoxetine, propranolol, triclosan, zinc-pyrithione and clotrimazole), which all showed to be toxic towards the algae, however only at concentrations below currently detected. Many pharmaceuticals are often simultaneously present in sewage treatment plant effluents. Hence, the exposed microbial communities in the recipient are subjected to a mixture of active substances. Mixtures do generally cause higher effects than each of their comprising substances alone, and it is therefore also important to consider also their combined toxicity. Based on the experimentally determined effects of the individual substances, two mathematical concepts have been suggested for predicting toxicity of mixtures comprised of similarly and dissimilarly acting substances: Concentration Addition (CA) and Independent Action (IA). Their applicability is generally accepted for single species assays, and the results in paper I and II in the thesis supports their validity also at a community level of biological complexity. However, both concepts are based on the assumption that no interactions occur between the mixture components. One such interaction would be the effect of chemosensitizing substances that inhibit bacterial efflux of antibiotics, thus increasing their toxicity beyond the predicted. Therefore, the combined effects of 3 proven chemosensitizers and the antibiotic ciprofloxacin on natural bacterial communities were investigated in paper IV. As opposed to results from clinical studies, no increased effects beyond what was predictable by IA were seen. Chemosensitization seems therefore be of low importance in natural bacterial communities. Poorly controlled pharmaceutical production facilities have recently been shown to release extremely high amounts antibiotics. Apart from the high toxicity of this pollution, concerns were raised with respect to bacterial resistance development in the receiving river. Therefore, the potential for tolerance development in microbial communities were assessed in paper III, using either treated effluent from an Indian production site or ciprofloxacin at corresponding concentrations. Both exposures induced tolerance of the bacterial communities towards ciprofloxacin, the effluent to the highest extent. However, whether this was due to resistance development or not needs to be further investigated. To conclude, this thesis shows that current environmental hazard assessment strategies for pharmaceuticals and antibiotics might not be realistic enough to protect natural microbial communities, and should therefore be extended accordingly. The results also emphasize the need to take complex environmental exposure situations into account, and to especially consider the combined toxicity of pharmalceuticals in the environment.
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| 6. |
- Brosché, Sara, 1978, et al.
(författare)
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Effects of two realistic pharmaceutical mixtures on natural freshwater periphyton communities
- 2007
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Ingår i: Society of Environmental Toxicology and Chemistry Europe annual meeting, 20-24 May 2006, Porto, Portugal.
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Konferensbidrag (refereegranskat)abstract
- During the last decade pharmaceuticals have been established as an important class of environmental pollutants. Main route of entry into the environment is from their regular use, which makes effluents from sewage treatment plants important sources of pollution. According to data from standard ecotoxicological tests, pharmaceuticals rarely pose an immediate risk at environmentally realistic concentrations. In reality though, pharmaceuticals act as mixtures on whole biological communities. Whether, and to what extent ecological effects can be expected under these circumstances is unknown. Hence we investigated the effects of two mixtures consisting of 15-20 pharmaceuticals on natural freshwater periphyton communities. The mixture compositions were based on effluent data from two sewage treatments plants, Ryaverket (Göteborg, Sweden) and Châtillon-sur-Chalaronne (Lyon, France). Effects on periphytic bacteria were measured as changes in metabolic diversity (Ecolog®). For the algal part of the communities, changes in pigment pattern and species composition were measured. Clear community-level effects were observed for the two mixtures
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| 7. |
- Brosché, Sara, 1978, et al.
(författare)
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Interactions in pharmaceutical mixtures -a challenge for predictive mixture ecotoxicology?
- 2009
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Ingår i: Society of Environmental Toxicology and Chemistry annual meeting, 31 May-4 June, Göteborg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- Low levels of antibiotics are found in sewage treatment plant effluents and their recipient waters all over the world. They differ from many other contaminants in that they are bioactive, i.e. especially designed to act on bacteria. In risk assessment of antibiotics, the European guidelines recommend the activated sludge respiration test to assess effects on bacteria and to ensure functionality of the sewage treatment process. The guidelines were developed for single substance assessments only, disregarding both any interactions in the complex mixture of antibiotics as well as effects on more sensitive environmental bacterial groups. For ecotoxicological hazard assessment of mixtures two mathematical concepts have been proposed, concentration addition and independent action. They have been shown to accurately predict the effect of multi component mixtures. However, they are valid only under the assumption that the mixture components do not interact with each other. Pharmacological studies have shown several mechanisms by which pharmaceuticals may enhance the effect of antibiotics, thus potentially causing deviations from the predictive concepts. The aim of this study was to investigate possible interaction mechanisms found in pharmaceutical mixtures, apply them on three environmental detection scenarios and finally assess the potential for deviations from the predictive concepts. In all three scenarios evaluated there was a theoretical potential for synergistic interactions in binary antibiotic and pharmaceutical combinations for about half of the 15-25 mixture components. In a simulated worst case scenario, the maximum deviation factor was one order of magnitude, i.e. within the same range as the smallest safety factor applied for pharmaceutical risk assessment.
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| 8. |
- Brosché, Sara, 1978, et al.
(författare)
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Joint Action of five antibiotics on limnic plankton communities
- 2006
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Ingår i: Society of Environmental Toxicology and Chemistry Europe annual meeting ,7-11 May 2006 The Haag, The Netherlands.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During the last decade pharmaceuticals have emerged as an important class of environmental pollutants. Antibiotics constitute a prominent part of this group, as they are used extensively both in human and veterinary medicine. Hence they have been detected in waste water effluents and surface waters in many countries, e.g. Sweden, Germany and Italy. The environmental concentrations typically do not provoke effects in standard acute toxicity tests. The standard tests give no consideration to the fact that the antibiotics exist in the environment as chemical mixtures acting on whole biological communities. Here we report on the individual toxicities and combination effects of the five commonly used antibiotics streptomycin, chloramphenicol, fusidic acid, chlorotetracycline and rifampicin, to limnic plankton communities. Toxicity was measured using 3H-Leucine incorporation as an endpoint. Furthermore we analysed the applicability of the classical mixture toxicity concepts Concentration Addition and Independent Action on this community level of biological complexity.
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| 9. |
- Brosché, Sara, 1978, et al.
(författare)
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Toxicity of five protein synthesis inhibiting antibiotics and their mixture to limnic bacterial communities
- 2010
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X. ; 99:4, s. 457-465
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Tidskriftsartikel (refereegranskat)abstract
- Antibiotics are common contaminants of aquatic environments, the protein synthesis inhibitors being one frequently detected class. Even though antibiotics target bacteria, little is known about the sensitivity of naturally occurring freshwater bacteria to these compounds. Limnic bacterial communities were therefore systematically exposed to five common protein synthesis inhibiting antibiotics, each representing a particular subgroup: streptomycin, chloramphenicol, fusidic acid, rifampicin and chlortetracycline. Full concentration–response curves and No Observed Effect Concentrations (NOECs) were determined for all antibiotics, using the 3Hleucine incorporation method. All test compounds were toxic to planktonic communities of limnic bacteria, with EC50s ranging from 0.138 μmol/L for chlortetracycline to 79.1 μmol/L for streptomycin. The order of toxicity was chlortetracycline > rifampicin > fusidic acid > chloramphenicol > streptomycin, based on the individual EC50 values. A comparison to reported chemical monitoring data shows that environmental concentrations of chlortetracycline are in a range that clearly inhibits the protein biosynthesis activity of planktonic bacterial communities. All compounds show exceptionally flat concentration–response relationship, for fusidic acid the ratio of EC50 to EC05 exceeds four orders of magnitude. This challenges the standard assessment factors of 10–100 for the extrapolation from high to low doses. Environmental exposure situations are often characterized by the presence of mixtures of antibiotics, e.g. in sewage effluents or river systems. Hence, also combined effects of the five antibiotics were determined, and compared to mixture toxicity predictions based on Concentration Addition and Independent Action. Concentration Addition slightly underestimated the observed EC50 by a factor of 1.5, independent on whether the prediction was based on single substance data that were recorded in parallel or whether historical data were used. Independent Action predicted higher mixture toxicity than Concentration Addition due to the flatness of the individual concentration–response curves. Implications of these findings for the environmental risk assessment of antibiotics and their mixtures are discussed.
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| 10. |
- Johansson, Henrik, 1984, et al.
(författare)
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Chronic toxicity of human pharmaceuticals to bacterial communities: evaluation of the mixture toxicity of sulfamethoxazole and trimethoprim.
- 2009
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Ingår i: SETAC Europe 19th Annual meeting, 31 May - 4 June, 2009, Göteborg..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Human pharmaceuticals are mainly emitted into the aquatic environment after use and some occur in detectable levels in aquatic ecosystems. Trimethoprim and sulfamethoxazole, two antibiotics both acting on folic acid synthesis but at different stages, have been found to co-occur. They are also administered in combination when treating urinary tract infections due to their synergistic effects. The aim of the study was to determine if a binary mixture of sulfamethoxazole and trimethoprim exert any synergistic effect on natural bacterial communities, or if the effects were predictable using Independent Action (IA). Glass discs (1,5 cm2) were submerged in the stream of Mölndalsån (20 km East of Gothenburg), on which natural periphyton communities (attached bacterial, microalgal and cyanobacterial communities) were colonised. The periphyton communities were taken into the lab after seven days of colonisation and were exposed to the toxicants in a semi static test for 72 hours. Two different background concentrations of trimethoprim (50nm, 5000nM) were combined with six different concentrations of sulfamethoxazole (16nM – 5000nM). Effects on the periphytic bacteria were measured as changes in metabolic diversity with the so called Biolog Ecoplates®, i.e. changes in the ability of the bacterial communities to utilise 31 different carbon sources. This served as a measure of toxicant-induced effects on bacterial community biomass and taxonomic composition. The combination effects were predictable by IA and no synergistic effects were noticed.
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| 11. |
- Larsson, D. G. Joakim, 1969, et al.
(författare)
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Release of active pharmaceutical ingredients from Indian bulk drug manufacture – environmental fate and effects on antibiotic resistance development, microbial ecosystems and vertebrate physiology
- 2008
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Ingår i: 2008 Society of Environmental Toxicology and Chemistry, November 16-20, Tampa, USA.
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Konferensbidrag (refereegranskat)abstract
- Last year, we published a paper showing extraordinary high levels of several drugs in treated effluent from a plant receiving process water from about 90 bulk drug manufacturers from the Hyderabad region in India. Particularly, the levels of various fluoroquinolones (up to 31 mg/L) called for more information on the potential development of antibiotic resistance of exposed bacteria, as well as potential ecological effects on microbial ecosystems. In this study we will present the first characterization of 93 strains of bacteria sampled inside the treatment facility for their sensitivity/resistance to 39 different antibiotics. Furthermore, controlled exposure experiments suggest that the treated effluent affects the functional structure of natural freshwater microbial communities at a dilution of 1:1000. Short to medium-term exposure experiments with frogs and fish demonstrate sublethal effects of the treated effluent at similar dilutions, suggesting that expected environmental effects are not restricted to disturbed microorganism communities. Data on the fate of different pharmaceuticals in a gradient up and downstream from the treatment facility will be presented, as well as levels in drinking water wells in seven nearby villages, showing a transport of drugs via the groundwater. We conclude that the environmental impact of drug production in the Hyderabad region is of great environmental concern. We will also present summary data on the origin of active substances present in pharmaceutical products on the Swedish market, implying an international responsibility for improving the environmental pollution situation related to bulk drug production in India.
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| 12. |
- Porsbring, Tobias, 1974, et al.
(författare)
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Effects of clotrimazole on the pigment composition of marine periphyton communities for use in predictive ecological mixture toxicity assessment
- 2006
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Ingår i: SETAC Europe 16th Annual Meeting, The Hague, The Netherlands.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Clotrimazole is a pharmaceutic fungicide classified as persistent and toxic according to EU Technical Guidance Document, and reaches the marine environment mainly from municipal waste water treatment plants together with several other pollutants. In a project to assess mixture toxicity of pharmaceuticals on microbial communities, clotrimazole effects on the development of periphyton were measured in two independent SWIFT tests in 2004 and 2005. Microalgal communities were precolonised in the Gullmar fjord on the west coast of Sweden on 1.5 cm2 glass discs. Following a 96h incubation in a concentration series of clotrimazole, periphyton pigment profiles were analysed using HPLC, and effects were calculated as Bray-Curtis dissimilarity indices. In both tests, a clotrimazole concentration of 11 microg/l had a significant effect on pigment composition with a NOEC of 3.45 microg/l (nominal). This indicates an approximately 5 times higher clotrimazole toxicity to algae than single species data, although comparisons to PEC values suggests a low risk for marine algae. However, the importance of clotrimazole for the risks of mixtures is further researched.
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