Time-course profiling of molecular stress responses to silver nanoparticles in the earthworm Eisenia fetida.

The molecular mechanism of silver nanoparticle (AgNP) toxicity, particularly its temporal aspect, is currently limited in the literature. This study seeks to identify and profile changes in molecular response patterns over time during soil exposure of the earthworm Eisenia fetida to AgNPs (82±27 nm) with reference to dissolved silver salt (AgNO3). Principal component analysis of selected gene and enzyme response profiles revealed dissimilar patterns between AgNO3 and AgNP treatments and also over time. Despite the observed difference in molecular profiles, the body burdens of total Ag were within the same range (10-40 mg/kg dry weight worm) for both treatments with apparent correlation to the induction pattern of metallothionein. AgNO3 induced the genes and enzymes related to oxidative stress at day 1, after which markers of energy metabolism were all suppressed at day 2. Exposure to AgNPs likewise led to induction of oxidative stress genes at day 2, but with a temporal pattern shift to immune genes at day 14 following metabolic upregulation at day 7. The involvement of oxidative stress and subsequent alterations in immune gene regulation were as predicted by our in vitro study reported previously, highlighting the importance of immunological endpoints in nanosilver toxicity.

Quantitative historical change in bumblebee (Bombus spp.) assemblages of red clover fields.

BACKGROUND: Flower visiting insects provide a vitally important pollination service for many crops and wild plants. Recent decline of pollinating insects due to anthropogenic modification of habitats and climate, in particular from 1950's onwards, is a major and widespread concern. However, few studies document the extent of declines in species diversity, and no studies have previously quantified local abundance declines. We here make a quantitative assessment of recent historical changes in bumblebee assemblages by comparing contemporary and historical survey data. METHODOLOGY/PRINCIPAL FINDINGS: We take advantage of detailed, quantitative historical survey data from the 1930's on bumblebee (Bombus spp.) abundances and species composition in red clover (Trifolium pratense) fields, an important floral resource and an attractant of all bumblebee species. We used the historical survey data as a pre-industrialization baseline, and repeated the same sampling protocol at nearly the same localities at present, hence setting up a historical experiment. We detected historical changes in abundances (bees/m(2)) of both workers (the "pollinatory units") and queens (effective population size), in addition to species composition. In particular, long-tongued bumblebee species showed consistent and dramatic declines in species richness and abundances throughout the flowering season of red clover, while short-tongued species were largely unaffected. Of 12 Bombus species observed in the 1930's, five species were not observed at present. The latter were all long-tongued, late-emerging species. CONCLUSIONS/SIGNIFICANCE: Because bumblebees are important pollinators, historical changes in local bumblebee assemblages are expected to severely affect plant reproduction, in particular long-tubed species, which are pollinated by long-tongued bumblebees.

Genetic variation of Zoarces viviparus: six populations revisited after about 35 years.

Totally, 417 eelpouts from six localities were collected in November-December 2007. Among these, 314 were females and from 246 of these females, one offspring was collected. The selected populations were also studied 36-38 years ago with the same technique, horizontal starch gel electrophoresis. The same enzymes were analysed at that time and now, but additional enzymes were analysed in the samples collected now, totally five enzymes representing 10 loci. A strong congruence in the genetic composition was found between the samples collected 36-38 years ago and those collected in 2007. No effect of pollutants in the environment was seen on the genetic variation by means of isozymes, but deformed offspring was observed and furthermore at one locality a high frequency of not pregnant females in the sample was observed.

Genetic variation in the enzyme esterase, bioaccumulation and life history traits in the earthworm Lumbricus rubellus from a metal contaminated area, Avonmouth, England.

Earthworms, Lumbricus rubellus, were collected in three successive years, 1997, 1998 and 1999 from 5, 6 and 4 sites, respectively, along a metal gradient near a smelter at Avonmouth, England. In total 271 worms were collected, 47 in 1997, 97 in 1998, and 127 in 1999. The worms were analysed for the enzyme esterase by means of agarose electrophoresis and for internal metal concentration. At one site collected in three successive years, 64 individuals of 66 were heterozygous for the esterase enzyme. The metal concentrations (Cu and Zn) in worms were significantly correlated with the total concentration and the CaCl2 extractable fraction of the metal in the soil. One of the homozygous esterase genotypes was significantly correlated with distance from the smelter, the extractable fraction of metals from soil, and the metal concentration in the worms. The other homozygous genotype was correlated with the CaCl2 extractable Cu and the Cu concentration in the worms. The internal levels of Cd, Cu, and Zn showed a higher classification potential (Discriminant Analysis) for 50 of 127 individuals, collected in 1999, when based on the original habitat of the earthworms than on the esterase genotype. The remaining 77 specimens, representing three sites, were exposed for 30 days in the laboratory to soils from four sites. For the individuals in this transplantation experiment, parameters measured were the esterase phenotype, internal metal concentration (Cd, Cu, and Zn), mortality, wet weight change, cocoon production, and cocoon hatching success. Cocoon production was highest among the worms from the most contaminated area, while worms from the least contaminated area had the highest hatching success. Neither the metal concentrations, in soil or internal, nor the life-history parameters could fully explain the genotypic distribution of esterase along the gradient. The internal concentrations of Cd, Cu and Zn in the worms used for the transplantation experiment showed the highest classification potential (Discriminant Analysis) when the prediction was based on the original habitat of the earthworms. The classification potential was less strong when based on esterase genotype and least on the transplantation conditions. Including life history traits did not enhance the prediction potential.

Critical analysis of soil invertebrate biomarkers: a field case study in Avonmouth, UK.

During the period 1996-1999 a joint field research programme (BIOPRINT-II) funded by the European Union was undertaken. The main objective of this project was the deployment of biochemical fingerprint techniques of soil invertebrate biomarkers for assessing the exposure and effect of toxicants on soil invertebrates in the field. The aim was to apply these techniques in the field focusing on a a chronically polluted field near a lead and zinc smelter in Avonmouth (UK). Therefore six sites were selected from which organisms were either sampled or transplanted to or from the laboratory. The project has provided a unique opportunity to apply a series of biological test methodologies in order to determine the hazard posed to soil sustainability and by inference soil biodiversity and function. This work has attempted to understand the linkage between effects measured at the molecular or cellular level and relate these to changes at higher levels of biological organisation. Here we evaluated the links between biomarkers and soil function parameters. The paper aims to summarize and explore the necessary caveats that must be understood before soil biomarker test systems may be used to strengthen the risk assessment process.