| 2. |
- Dupont, Chris L., et al.
(författare)
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Functional Tradeoffs Underpin Salinity-Driven Divergence in Microbial Community Composition
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e89549-
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity.
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| 3. |
- Malkiewicz, Katarzyna, et al.
(författare)
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Human experts' judgment of chemicals reactivity for identification of hazardous chemicals
- 2009
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Ingår i: Toxicology Letters. - : Elsevier BV. - 0378-4274 .- 1879-3169. ; 189, s. S243-S243
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The development of non-testing approaches for the identification of chemicals with the potential to cause environmental hazards, have gained increased attention. In this study the hypothesis that experts’ judgement of chemical reactivity could be used for this purpose has been tested. The judgments of chemical reactivity for 200 organic chemicals, based on their molecular structure were performed by four senior organic and environmental chemists. Potentials for reactivity (namely: oxidative/reductive reactivity, hydrolysis, direct photolysis, reactivity towards radicals) were scored on the 1– scale. Both the experts’ individual judgment, and a compromised judgment after joint discussion for clarification of cases with divergent opinions, was analysed. Furthermore we searched for relations between the expert judgement data and: (a) the chemical characteristics representedby 40 chemical descriptors using partial least squares regression (PLS), and (b) experimental and in silico data for different toxicological and physico-chemical end-points. The results of on-going analyses indicate that for the majority of the chemicals, the individual judgments differed significantly between experts but after discussion among the experts for clarification, the judgments becamemuch more concurrent. The relation between averaged experts’ predicted photolytic degradation potential and chemical characteristic based on a PLS model (with three significant components explaining 76% of the variation) was found. We have also found that in the group of the chemicals with the higher score of the experts judged oxidative reactivity there was higher percentage of biodegradable chemicals when compar
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