| 1. |
- Beltman, B., et al.
(författare)
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Phosphate Release Upon Long- and Short -Term Flooding of Fen Meadows Depends on Land Use History and Soil pH
- 2014
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Ingår i: Wetlands (Wilmington, N.C.). - : Springer Netherlands. - 0277-5212 .- 1943-6246. ; 34:5, s. 989-1001
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Tidskriftsartikel (refereegranskat)abstract
- Flooding of acidified and desiccated fen meadows is a management approach for mitigating loss of plant species as well as a short-term measure to prevent flooding in urban areas. Studies have shown that flooding events can cause extreme P release from soils. We questioned whether the occurrence of this 'internal eutrophication' from flooding depended on fertilization history and soil pH. A greenhouse experiment with soil cores from Ireland (turloughs) and from the Netherlands, exposed to flooding for 216 days (long-term) showed a substantial P release for sites with a history of fertilizer use only. Short-term flooding (20-25 days) caused little P release in all soils. There was no correlation between P release and initial soil pH (range 4.1-7.1). All flooded soils showed a significant decline in sulfate and increased iron in the pore water upon flooding. Field trials applying short term flooding to sites differing in soil pH, average soil moisture and history of fertilizer application showed there was no overall effect of flooding on phosphate, nitrate, ammonium, iron concentrations and pH of pore water. Sulfate concentrations significantlyincreased. Hence, problematic phosphate release is only induced by long term flooding of fen meadows with a history of fertilization.
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| 2. |
- Sarneel, Judith M., et al.
(författare)
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The role of wind in the dispersal of floating seeds in slow-flowing or stagnant water bodies
- 2014
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Ingår i: Journal of Vegetation Science. - : WILEY-BLACKWELL. - 1100-9233 .- 1654-1103. ; 25:1, s. 262-274
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Tidskriftsartikel (refereegranskat)abstract
- QuestionWhat is the role of wind in the dispersal of waterborne seeds in slow-flowing and stagnant water bodies at different temporal and spatial scales? (i) Is there a direct effect of wind on seed dispersal speed and distance? (ii) Are prevailing wind conditions reflected in the seed deposition patterns during a year? (iii) What are the long-term (multiple year) effects of prevailing wind conditions on the pattern and composition of shoreline seed banks? LocationThe Westbroekse Zodden (5210N; 507E) and De Weerribben (52 degrees 46N; 5 degrees 55E) fen reserves in The Netherlands. MethodsReal-time seed movement tracking experiments were conducted at different wind speeds. Additionally, we performed a seed trap experiment using artificial grass mats and carried out seed bank analyses using a seedling emergence test. ResultsWind speed and direction strongly determined the dispersal process and the resulting deposition patterns of floating seeds in shallow lakes or ponds. Wind speed directly influenced dispersal speed and distance. Increasing wind speed increased dispersal speed but decreased dispersal distance. Over multiple seasons, more seeds were deposited at downwind shorelines than at upwind shorelines, showing that wind-driven hydrochory resulted in directional transport according to the prevailing wind direction. The species composition of deposited seeds was also affected, with proportionally more water-dispersed seeds being deposited at down-wind shorelines. These effects of wind speed and directionality will have consequences for the colonization of riparian zones in lentic systems and, therefore, also influence management and restoration. In the long term, local seed banks in riparian zones reflected the prevailing wind conditions poorly, showing that additional processes, such as differential germination and predation, also play important roles at longer time scales. ConclusionsWind plays an important role in the dispersal of waterborne seeds in lentic systems and (prevailing) wind speed and direction are reflected in seed dispersal trajectories and deposition patterns.
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| 3. |
- van der Stel, Wanda, et al.
(författare)
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Mapping the cellular response to electron transport chain inhibitors reveals selective signaling networks triggered by mitochondrial perturbation
- 2022
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 96:1, s. 259-285
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial perturbation is a key event in chemical-induced organ toxicities that is incompletely understood. Here, we studied how electron transport chain (ETC) complex I, II, or III (CI, CII and CIII) inhibitors affect mitochondrial functionality, stress response activation, and cell viability using a combination of high-content imaging and TempO-Seq in HepG2 hepatocyte cells. CI and CIII inhibitors perturbed mitochondrial membrane potential (MMP) and mitochondrial and cellular ATP levels in a concentration- and time-dependent fashion and, under conditions preventing a switch to glycolysis attenuated cell viability, whereas CII inhibitors had no effect. TempO-Seq analysis of changes in mRNA expression pointed to a shared cellular response to CI and CIII inhibition. First, to define specific ETC inhibition responses, a gene set responsive toward ETC inhibition (and not to genotoxic, oxidative, or endoplasmic reticulum stress) was identified using targeted TempO-Seq in HepG2. Silencing of one of these genes, NOS3, exacerbated the impact of CI and CIII inhibitors on cell viability, indicating its functional implication in cellular responses to mitochondrial stress. Then by monitoring dynamic responses to ETC inhibition using a HepG2 GFP reporter panel for different classes of stress response pathways and applying pathway and gene network analysis to TempO-Seq data, we looked for downstream cellular events of ETC inhibition and identified the amino acid response (AAR) as being triggered in HepG2 by ETC inhibition. Through in silico approaches we provide evidence indicating that a similar AAR is associated with exposure to mitochondrial toxicants in primary human hepatocytes. Altogether, we (i) unravel quantitative, time- and concentration-resolved cellular responses to mitochondrial perturbation, (ii) identify a gene set associated with adaptation to exposure to active ETC inhibitors, and (iii) show that ER stress and an AAR accompany ETC inhibition in HepG2 and primary hepatocytes.
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