@article{MeliAuclercPalmqvistetal.2013,
  author    = {Meli, Mattia and Auclerc, Apolline and Palmqvist, Annemette and Forbes, Valery E. and Grimm, Volker},
  title     = {Population-level consequences of spatially heterogeneous exposure to heavy metals in soil an individual-based model of springtails},
  series = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog},
  volume    = {250},
  journal   = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0304-3800},
  doi       = {10.1016/j.ecolmodel.2012.11.010},
  pages     = {338 -- 351},
  year      = {2013},
  abstract  = {Contamination of soil with toxic heavy metals poses a major threat to the environment and human health. Anthropogenic sources include smelting of ores, municipal wastes, fertilizers, and pesticides. In assessing soil quality and the environmental and ecological risk of contamination with heavy metals, often homogeneous contamination of the soil is assumed. However, soils are very heterogeneous environments. Consequently, both contamination and the response of soil organisms can be assumed to be heterogeneous. This might have consequences for the exposure of soil organisms and for the extrapolation of risk from the individual to the population level. Therefore, to explore how soil contamination of different spatial heterogeneity affects population dynamics of soil invertebrates, we developed a spatially explicit individual-based model of the springtail, Folsomia candida, a standard test species for ecotoxicological risk assessment. In the model, individuals were assumed to sense and avoid contaminated habitat with a certain probability that depends on contamination level. Avoidance of contaminated areas thus influenced the individuals' movement and feeding, their exposure, and in turn all other biological processes underlying population dynamics. Model rules and parameters were based on data from the literature, or were determined via pattern-oriented modelling. The model correctly predicted several patterns that were not used for model design and calibration. Simulation results showed that the ability of the individuals to detect and avoid the toxicant, combined with the presence of clean habitat patches which act as "refuges", made equilibrium population size due to toxic effects less sensitive to increases in toxicant concentration. Additionally, the level of heterogeneity among patches of soil (i.e. the difference in concentration) was important: at the same average concentration, a homogeneously contaminated scenario was the least favourable habitat, while higher levels of heterogeneity corresponded to higher population growth rate and equilibrium size. Our model can thus be used as a tool for extrapolating from short-term effects at the individual level to long-term effects at the population level under more realistic conditions. It can thus be used to develop and extrapolate from standard ecotoxicological tests in the laboratory to ecological risk assessments.},
  language  = {en}
}
@article{RademacherHoffmannLackmannetal.2012,
  author    = {Rademacher, Corinna and Hoffmann, Marie-Christine and Lackmann, Jan-Wilm and Moser, Roman and Pf{\"a}nder, Yvonne and Leimk{\"u}hler, Silke and Narberhaus, Franz and Masepohl, Bernd},
  title     = {Tellurite resistance gene trgB confers copper tolerance to Rhodobacter capsulatus},
  series = {BioMetals : an international journal on the role of metal ions in biology, biochemistry and medicine},
  volume    = {25},
  journal   = {BioMetals : an international journal on the role of metal ions in biology, biochemistry and medicine},
  number    = {5},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0966-0844},
  doi       = {10.1007/s10534-012-9566-2},
  pages     = {995 -- 1008},
  year      = {2012},
  abstract  = {To identify copper homeostasis genes in Rhodobacter capsulatus, we performed random transposon Tn5 mutagenesis. Screening of more than 10,000 Tn5 mutants identified tellurite resistance gene trgB as a so far unrecognized major copper tolerance determinant. The trgB gene is flanked by tellurite resistance gene trgA and cysteine synthase gene cysK2. While growth of trgA mutants was only moderately restricted by tellurite, trgB and cysK2 mutants were severely affected by tellurite, which implies that viability under tellurite stress requires increased cysteine levels. Mutational analyses revealed that trgB was the only gene in this chromosomal region conferring cross-tolerance towards copper. Expression of the monocistronic trgB gene required promoter elements overlapping the trgA coding region as shown by nested deletions. Neither copper nor tellurite affected trgB transcription as demonstrated by reverse transcriptase PCR and trgB-lacZ fusions. Addition of tellurite or copper gave rise to increased cellular tellurium and copper concentrations, respectively, as determined by inductively coupled plasma-optical emission spectroscopy. By contrast, cellular iron concentrations remained fairly constant irrespective of tellurite or copper addition. This is the first study demonstrating a direct link between copper and tellurite response in bacteria.},
  language  = {en}
}