Environmental pollution and nutritional quality modulate immune response of the wood mouse (Apodemus sylvaticus) through hormonal disturbances.

Cadmium (Cd) and lead (Pb) are known to enhance immune cell damages and to decrease cellular immunity, promoting higher susceptibility to infectious diseases. Selenium (Se) is an essential element involved in immunity and reactive oxygen species scavenging. This study aimed at evaluating how Cd and Pb and low nutritional (Se) quality modulate immune response to a bacterial lipopolysaccharide (LPS) challenge in wood mice (Apodemus sylvaticus). Mice were trapped near a former smelter in northern France in sites of High or Low contamination. Individuals were challenged immediately after capture or after five days of captivity, fed a standard or a Se-deficient diet. Immune response was measured with leukocyte count and plasma concentration of TNF-α, a pro-inflammatory cytokine. Faecal and plasma corticosterone (CORT), a stress-hormone involved in anti-inflammatory processes, was measured to assess potential endocrine mechanisms. Higher hepatic Se and lower faecal CORT were measured in free-ranging wood mice from High site. LPS-challenged individuals from High site showed steeper decrease of circulating leukocytes of all types, higher TNF-α concentrations, and a significant increase of CORT, compared to individuals from Low site. Challenged captive animals fed standard food exhibited similar patterns (decrease of leukocytes, increase of CORT, and detectable levels of TNF-α), with individuals from lowly contaminated site having higher immune responses than their counterparts from highly polluted site. Animals fed Se-deficient food exhibited lymphocytes decrease, no CORT variation, and average levels of TNF-α. These results suggest (i) a higher inflammatory response to immune challenge in free-ranging animals highly exposed to Cd and Pb, (ii) a faster recovery of inflammatory response in animals lowly exposed to pollution when fed standard food than more exposed individuals, and (iii) a functional role of Se in the inflammatory response. The role of Se and mechanisms underlying the relationship between glucocorticoid and cytokine remain to be elucidated.

Effects of chronic exposure to toxic metals on haematological parameters in free-ranging small mammals.

Blood circulates through the vascular system to carry oxygen, nutrients and metabolites to and away from tissues, and as such is a key-component of animal physiology. The impacts of metal pollution on blood, however, are poorly documented in free-ranging vertebrates. While the counteracting effect of selenium on mercury toxicity is well known in marine mammals, its potential role against the toxicity of other metals is less studied, especially on terrestrial wildlife. We explored the consequences of chronic exposure to two non-essential metals (cadmium and lead) along a pollution gradient in Northern France, on eleven haematological parameters in two free ranging small mammals, the wood mouse Apodemus sylvaticus and the bank vole Myodes glareolus. We hypothesized that haematology was related to metal concentrations in tissues, and that selenium might exert modulating effects. Concentrations of cadmium and lead in the tissues indicated an increased chronic exposure to and accumulation of metals along the gradient. Some haematological parameters were not explained by any measured variables while some others varied only with gender or age. Red blood cells, red blood cells distribution width, and blood iron concentration, however, decreased with increasing cadmium in the tissues in wood mice. Red blood cells and haemoglobin decreased with increasing renal lead and hepatic cadmium, respectively, in bank voles. Red blood cells distribution width in wood mice increased with cadmium concentrations in the liver but this was counteracted by high selenium levels in the same organ. An interaction of selenium and lead on red blood cells was also observed in bank voles. Further, selenium concentrations were associated with an increase of monocytes in wood mice. The present results show that toxic metals were related to haematology changes, particularly erythrocyte indicators, and that some essential elements like selenium should be measured as well since they may counteract toxic effects.

Pervasive exposure of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes.

Knowledge gaps regarding the potential role of pesticides in the loss of agricultural biodiversity worldwide and mixture-related issues hamper proper risk assessment of unintentional impacts of pesticides, rendering essential the monitoring of wildlife exposure to these compounds. Free-ranging mammal exposure to legacy (Banned and Restricted: BRPs) and currently used (CUPs) pesticides was investigated, testing the hypotheses of: (1) a background bioaccumulation for BRPs whereas a "hot-spot" pattern for CUPs, (2) different contamination profiles between carnivores and granivores/omnivores, and (3) the role of non-treated areas as refuges towards exposure to CUPs. Apodemus mice (omnivore) and Crocidura shrews (insectivore) were sampled over two French agricultural landscapes (n = 93). The concentrations of 140 parent chemicals and metabolites were screened in hair samples. A total of 112 compounds were detected, showing small mammal exposure to fungicides, herbicides and insecticides with 32 to 65 residues detected per individual (13-26 BRPs and 18-41 CUPs). Detection frequencies exceeded 75% of individuals for 13 BRPs and 25 CUPs. Concentrations above 10 ng/g were quantified for 7 BRPs and 29 CUPs (in 46% and 72% of individuals, respectively), and above 100 ng/g for 10 CUPs (in 22% of individuals). Contamination (number of compounds or concentrations) was overall higher in shrews than rodents and higher in animals captured in hedgerows and cereal crops than in grasslands, but did not differ significantly between conventional and organic farming. A general, ubiquitous contamination by legacy and current pesticides was shown, raising issues about exposure pathways and impacts on ecosystems. We propose a concept referred to as "biowidening", depicting an increase of compound diversity at higher trophic levels. This work suggests that wildlife exposure to pesticide mixtures is a rule rather than an exception, highlighting the need for consideration of the exposome concept and questioning appropriateness of current risk assessment and mitigation processes.

Vegetation shapes aboveground invertebrate communities more than soil properties and pollution: a preliminary investigation on a metal-contaminated site.

Pollution with trace metals (TM) has been shown to affect diversity and/or composition of plant and animal communities. While ecotoxicological studies have estimated the impact of TM contamination on plant and animal communities separately, ecological studies have widely demonstrated that vegetation is an important factor shaping invertebrate communities. It is supposed that changes in invertebrate communities under TM contamination would be explained by both direct impact of TM on invertebrate organisms and indirect effects due to changes in plant communities. However, no study has clearly investigated which would more importantly shape invertebrate communities under TM contamination. Here, we hypothesized that invertebrate communities under TM contamination would be affected more importantly by plant communities which constitute their habitat and/or food than by direct impact of TM. Our analysis showed that diversity and community identity of flying invertebrates were explained only by plant diversity which was not affected by TM contamination. Diversity of ground-dwelling (GD) invertebrates in spring was explained more importantly by plant diversity (27% of variation) than by soil characteristics including TM concentrations (8%), whereas their community identity was evenly explained by plant diversity and soil characteristics (2-7%). In autumn, diversity of GD invertebrates was only explained by plant diversity (12%), and their identity was only explained by soil characteristics (8%). We conclude that vegetation shapes invertebrate communities more importantly than direct effects of TM on invertebrates. Vegetation should be taken into account when addressing the impacts of environmental contamination on animal communities.

How Do Richness and Composition of Diet Shape Trace Metal Exposure in a Free-Living Generalist Rodent, Apodemus sylvaticus.

Exposure of terrestrial mammals to chemical contaminants like trace metals (TMs) is considered to be mainly based on trophic transfer. Although relationships between TM transfer to animals and identity of contaminated food have been studied, the variation of the TM transfer with respect to diet diversity has been poorly documented. In this study, the oral exposure to TMs of wood mice Apodemus sylvaticus was investigated with respect to both the number of different items, i.e., diet richness, and the identity of items determined by metabarcoding from their stomach content, i.e., diet composition. The results showed that consuming Salicaceae, a known cadmium accumulator plant family, significantly increased exposure to cadmium and zinc. However, an increase in diet richness minimized exposure to cadmium when mice consumed Salicaceae items. This strongly suggests that TM accumulator items can lead to a high oral exposure to TMs but that such high exposure due to TM accumulator items can be " diluted" by diet richness due to other low accumulator items. Our results clearly indicate that both the presence of certain items in the diet and diet richness are important determinants of exposure to TMs in generalist animals, which matches the predictions of the " diet dilution hypothesis".

Is blood a reliable indicator of trace metal concentrations in organs of small mammals?

In wildlife ecotoxicology, the rationale for using blood rather than other body fluids or tissues is that sampling blood is a minimally invasive technique without animal mortality, providing both ethical and scientific benefits. To date, few studies are available on the relationships between blood and organ metal concentrations of small mammals living in contaminated sites. The present work aimed to study the relationships between the concentrations of 18 essential and nonessential metals in blood and their concentrations in the liver and kidneys, two accumulation and target organs, in wood mice from a former lead and zinc smelter, Metaleurop Nord, in northern France. The results from Se, Pb and Tl indicate that blood levels may be used to predict concentrations in organs of small mammals. Conversely, for Cd, Cu, Fe, Mo, Ti and Zn, blood concentrations were poorly or not related to liver and kidney concentrations. In addition to accurately predicting the concentrations of some metals in target organs, blood can provide important information about the physiological and biochemical status of organisms, but further toxicokinetic research is required to develop the use of blood sampling as a minimally invasive biomonitoring and ecotoxicological method in wildlife.

Does pollution influence small mammal diet in the field? A metabarcoding approach in a generalist consumer.

Mammals are mainly exposed to trace metals (TMs) via consuming contaminated food. Several studies have demonstrated relationships between metal concentrations in food and in animal tissues. However, potential effects of TMs on feeding behaviour of wildlife have been poorly documented under field conditions, despite experimental evidence showing that food selection is impacted by resource contamination. Here, we test the hypothesis that the diet of a generalist rodent, the wood mouse (Apodemus sylvaticus), is altered by soil TM contamination in the field. Wood mice were sampled in spring and in autumn along a gradient of soil contamination in the surroundings of a former smelter located in northern France. Available resources in the field were inventoried, and the diet of the animals was analysed using DNA "metabarcoding." We demonstrated that (a) relationship between the resource richness in the diet and their richness in the field was altered by soil metal contamination. Wood mice specialized their diet along the gradient of soil metal contamination for both plant and invertebrate resources in spring. We also showed that (b) preference for Salicaceae, a plant family accumulating metals, decreased when soil contamination increased. These results suggest that environmental TM pollution could act as a force modulating trophic interactions in terrestrial food webs, thereby affecting wildlife exposure to contaminants by trophic route.

Trace metals from historical mining sites and past metallurgical activity remain bioavailable to wildlife today.

Throughout history, ancient human societies exploited mineral resources all over the world, even in areas that are now protected and considered to be relatively pristine. Here, we show that past mining still has an impact on wildlife in some French protected areas. We measured cadmium, copper, lead, and zinc concentrations in topsoils and wood mouse kidneys from sites located in the Cévennes and the Morvan. The maximum levels of metals in these topsoils are one or two orders of magnitude greater than their commonly reported mean values in European topsoils. The transfer to biota was effective, as the lead concentration (and to a lesser extent, cadmium) in wood mouse kidneys increased with soil concentration, unlike copper and zinc, providing direct evidence that lead emitted in the environment several centuries ago is still bioavailable to free-ranging mammals. The negative correlation between kidney lead concentration and animal body condition suggests that historical mining activity may continue to play a role in the complex relationships between trace metal pollution and body indices. Ancient mining sites could therefore be used to assess the long-term fate of trace metals in soils and the subsequent risks to human health and the environment.

A full life-cycle bioassay with Cantareus aspersus shows reproductive effects of a glyphosate-based herbicide suggesting potential endocrine disruption.

A full life-cycle (240 days) bioassay using the terrestrial snail, Cantareus aspersus, allowing exposure during embryogenesis and/or the growth and reproduction phases, was used to assess the effects of Bypass®, a glyphosate-based herbicide (GlyBH), on a range of endpoints, including parameters under endocrine control. As a positive control, a mixture (R-A) made of diquat (Reglone®) and nonylphenols (NP, Agral®), known for its endocrine disrupting effects in other organisms, was tested. At environmental concentrations, both pesticides (R-A mixture and GlyBH) enhanced growth but reduced reproduction. The R-A mixture acted mainly on the fecundity through a delay in egg-laying of approximately 20 days and a strongly reduced number of clutches. This latter dysfunction may be caused by a permanent eversion of the penis, suggesting a disrupting effect at the neuro-endocrine level, which prevented normal mating. GlyBH acted on fertility, possibly due to a decrease in the fertilization of eggs laid by adults exposed during their embryonic development. These results, associated with the absence of observed effects on gonad histology of GlyBH exposed snails, suggested that the underlying mechanisms are neuro-endocrine.

Negative impact of urban habitat on immunity in the great tit Parus major.

Urban habitats are described as having an overall negative influence on many fitness-related traits in several bird species, but a vital function such as immunity remains poorly studied. The immune response is strongly linked to individual condition, which partly depends on resource availability and the parasitic context that often differ between urban and natural habitats. A difference between the immunity of populations dwelling in urban areas and populations from more natural habitats can, therefore, be hypothesized. We conducted a 2-year experimental study on great tits (Parus major) in urban and forest areas. We stimulated the constitutive immunity of nestlings and assessed both the inflammatory response by measuring the plasma levels of haptoglobin, an inflammatory marker, and its activation cost through the loss of body mass. In addition, we checked the nestlings for ectoparasites and assessed haemosporidian prevalence in adults. Nestlings from urban sites produced relatively less haptoglobin and lost more body mass than those from forest sites, which suggests that the activation of constitutive immunity is more costly for birds living in urban sites than for those living in the forest. We detected no ectoparasite in birds in both habitats. However, urban adults showed lower haemosporidian prevalence than forest ones, suggesting a reduced exposure to these parasites and their vectors in towns. Overall, our study provides evidence for an immune difference between urban and forest populations. Because immunity is crucial for organism fitness, it is of prime interest to identify causes and processes at the origin of this difference.

Differential expression of metallothionein isoforms in terrestrial snail embryos reflects early life stage adaptation to metal stress.

The aim of this study was to analyze the expression of three metallothionein (MT) isoform genes (CdMT, CuMT and Cd/CuMT), already known from adults, in the Early Life Stage (ELS) of Cantareus aspersus. This was accomplished by detection of the MT isoform-specific transcription adopting Polymerase Chain Reaction (PCR) amplification and quantitative Real Time (qRT)-PCR of the three MT genes. Freshly laid eggs were kept for 24 hours under control conditions or exposed to three cadmium (Cd) solutions of increasing concentration (5, 10, and 15 mg Cd/L). The transcription of the three MT isoform genes was detected via PCR in 1, 6 and 12-day-old control or Cd-exposed embryos. Moreover, the transcription of this isoform genes during development was followed by qRT-PCR in 6 and 12-day-old embryos. Our results showed that the CdMT and Cd/CuMT genes, but not the CuMT gene, are expressed in embryos at the first day of development. The transcription of the 3 MT genes in control embryos increased with development time, suggesting that the capacities of metal regulation and detoxification may have gradually increased throughout embryogenesis. However in control embryos, the most highly expressed MT gene was that of the Cd/CuMT isoform, whose transcription levels greatly exceeded those of the other two MT genes. This contrasts with the minor significance of this gene in adult snails and suggests that in embryos, this isoform may play a comparatively more important role in metal physiology compared to adult individuals. This function in adult snails appears not to be related to Cd detoxification. Instead, snail embryos responded to Cd exposure by over-expression of the CdMT gene in a concentration-dependent manner, whereas the expression of the Cd/CuMT gene remained unaffected. Moreover, our study demonstrates the ability of snail embryos to respond very early to Cd exposure by up-regulation of the CdMT gene.

Blood parameters as biomarkers of cadmium and lead exposure and effects in wild wood mice (Apodemus sylvaticus) living along a pollution gradient.

Small mammal populations living on contaminated sites are exposed to various chemicals. Lead (Pb) and cadmium (Cd), two well-known nonessential trace metals, accumulate in different organs and are known to cause multiple adverse effects. To develop nonlethal markers in ecotoxicology, the present work aimed to study the relationships between blood parameters (hematocrit, leukocyte levels and granulated erythrocyte levels) and Cd and Pb concentrations in the soil and in the liver and kidneys of wood mice (Apodemus sylvaticus). Individuals were trapped along a pollution gradient with high levels of Cd, Pb and zinc (Zn) contamination. The results indicated that hematological parameters were independent of individual characteristics (age and gender). Blood parameters varied along the pollution gradient, following a pattern similar to the accumulation of Cd in the organs of the wood mice. No relationship was found between the blood parameters studied and Pb concentrations in the organs or in the environment. The hematocrit and leukocyte number decreased with increasing concentrations of Cd in the kidneys and/or in the liver. Moreover, the hematocrit was lower in the animals that were above the thresholds (LOAELs) for Cd concentrations in the liver. These responses were interpreted as a warning of potential negative effects of Cd exposure on the oxygen transport capacity of the blood (e.g., anemia). The present results suggest that blood parameters, notably hematocrit, may offer a minimally invasive biomarker for the evaluation of Cd exposure in further ecotoxicological studies.

An assessment of the embryotoxicity of cadmium in the terrestrial mollusk Cantareus aspersus: from bioaccumulation to impacts at different levels of biological organization.

This study aims to determine various parameters that allow the evaluation of the toxicity of chemicals to embryos of the ubiquitous land snail Cantareus aspersus. For this purpose, we investigated morphological and physiological endpoints in control embryos and in embryos exposed to a solution of 6mg Cd/L (CdCl2) in a liquid phase bioassay: size at days 3, 6 and 10, heart rate at 7 days, delay in hatching, states of development of non-hatched eggs after 17 days and the fresh mass of newly hatched embryos. The kinetics of Cd accumulation in eggs and DNA fragmentation were also measured. The first detectable sign of adverse effects appeared after 7 days of development, when the heart rate decreased in Cd-exposed embryos compared with the control. After 10 days of exposure, Cd-exposed hatchlings exhibited a lower fresh mass than control individuals. The majority (75 percent) of non-hatched embryos at 17 days was dead and presented signs of disaggregation or malformations. The hatching of Cd-exposed eggs was delayed 4 days, and DNA fragmentation was later detected after 20 days of Cd exposure. The measurement of Cd in the eggs showed that concentrations are relatively stable during the exposure period from 3 days (20-27µg Cd/g DW) to the end of exposure. The present study completes the range of endpoints that can be used to study the effects of contaminants and provides new parameters that are readily measured throughout the embryonic development of a terrestrial mollusk.

Hair as a noninvasive tool for risk assessment: do the concentrations of cadmium and lead in the hair of wood mice (Apodemus sylvaticus) reflect internal concentrations?

There is an increasing need for developing noninvasive markers of accumulation when studying the transfer of pollutants in wildlife, in response to problems caused by sacrifice of animals (disturbed population dynamics, respect of ethical protocols). Thus, the aim of this work was to determine whether trace metal (TM) concentrations in hair could be used as an accurate noninvasive estimator of internal and environmental concentrations. For that purpose, on a 40km² site surrounding an ancient smelter, 321 wood mice (Apodemus sylvaticus) were sampled on seven squares (500×500m) and 4 squares in fall 2010 and spring 2011, respectively. The relationships between the cadmium (Cd) and lead (Pb) concentrations in hair and those in the liver, kidneys, and soils were described. The results indicated that hair concentration was a relatively good predictor of Pb concentrations in organs (p<0.001, 0.46

Predicting As, Cd, Cu, Pb and Zn levels in grasses (Agrostis sp. and Poa sp.) and stinging nettle (Urtica dioica) applying soil-plant transfer models.

The aim of this study was to derive regression-based soil-plant models to predict and compare metal(loid) (i.e. As, Cd, Cu, Pb and Zn) concentrations in plants (grass Agrostis sp./Poa sp. and nettle Urtica dioica L.) among sites with a wide range of metal pollution and a wide variation in soil properties. Regression models were based on the pseudo total (aqua-regia) and exchangeable (0.01 M CaCl2) soil metal concentrations. Plant metal concentrations were best explained by the pseudo total soil metal concentrations in combination with soil properties. The most important soil property that influenced U. dioica metal concentrations was the clay content, while for grass organic matter (OM) and pH affected the As (OM) and Cu and Zn (pH). In this study multiple linear regression models proved functional in predicting metal accumulation in plants on a regional scale. With the proposed models based on the pseudo total metal concentration, the percentage of variation explained for the metals As, Cd, Cu, Pb and Zn were 0.56%, 0.47%, 0.59%, 0.61%, 0.30% in nettle and 0.46%, 0.38%, 0.27%, 0.50%, 0.28% in grass.

Histopathology related to cadmium and lead bioaccumulation in chronically exposed wood mice, Apodemus sylvaticus, around a former smelter.

The ceasing of industrial activities often reduces the emission of pollutants but also often leaves disturbed areas without remediation and with persistent pollutants that can still be transferred along the food chain. This study examines the potential relationships between non-essential trace metals and histopathology in target tissues of wood mice (Apodemus sylvaticus) collected along a gradient of contamination around the former smelter, Metaleurop Nord (northern France). Cadmium and lead concentrations were measured, and histological alterations attributable to chronic trace metal exposure were assessed in the liver and the kidneys of 78 individuals. Metal concentrations quantified in the present study were among the highest observed for this species. Some histological alterations significantly increased with Cd or Pb concentrations in the soil and in the organs. Sixteen mice from polluted sites were considered at risk for metal-induced stress because their Cd and/or Pb tissue concentrations exceeded the LOAELs for single exposure to these elements. These mice also exhibited a higher severity of histological alterations in their organs than individuals with lower metal burdens. These results indicate that the Metaleurop smelter, despite its closure in 2003, still represents a threat to the local ecosystem because of the high levels and high bioavailability of Cd and Pb in the soil. However, among the mice not considered at risk for metal-induced stress based on the metal levels in their tissues, a large percentage of individuals still exhibited histological alterations. Thus, the present study suggests that the evaluation of toxic effects based only on the LOAELs for single metal exposure may result in the underestimation of the real risks when specimens are exposed to multiple stressors.

Unintentional wildlife poisoning and proposals for sustainable management of rodents.

In Europe, bromadiolone, an anticoagulant rodenticide authorized for plant protection, may be applied intensively in fields to control rodents. The high level of poisoning of wildlife that follows such treatments over large areas has been frequently reported. In France, bromadiolone has been used to control water voles (Arvicola terrestris) since the 1980s. Both regulation and practices of rodent control have evolved during the last 15 years to restrict the quantity of poisoned bait used by farmers. This has led to a drastic reduction of the number of cases of poisoned wildlife reported by the French surveillance network SAGIR. During the autumn and winter 2011, favorable weather conditions and high vole densities led to the staging of several hundreds of Red Kites (Milvus milvus) in the Puy-de-Dôme department (central France). At the same time, intensive treatments with bromadiolone were performed in this area. Although no misuse has been mentioned by the authorities following controls, 28 Red Kites and 16 Common Buzzards (Buteo buteo) were found dead during surveys in November and December 2011. For all these birds, poisoning by bromadiolone as the main cause of death was either confirmed or highly suspected. Other observations suggest a possible impact of bromadiolone on the breeding population of Red Kites in this area during the spring 2011. French regulation of vole control for plant protection is currently under revision, and we believe this event calls for more sustainable management of rodent outbreaks. Based on large-scale experiments undertaken in eastern France, we propose that direct control of voles at low density (with trapping or limited chemical treatments) and mechanical destruction of vole tunnels, mole control, landscape management, and predator fostering be included in future regulation because such practices could help resolve conservation and agricultural issues.

Responses of wild small mammals to arsenic pollution at a partially remediated mining site in Southern France.

Partial remediation actions at a former gold mine in Southern France led to a mosaic of contaminated and rehabilitated zones. In this study, the distribution of arsenic and its potential adverse effects on small mammals were investigated. The effectiveness of remediation for reducing the transfer of this element into wildlife was also discussed. Arsenic levels were measured in the soil and in the stomach contents, livers, kidneys, and lungs of four small mammal species (the wood mouse (Apodemus sylvaticus), the Algerian mouse (Mus spretus), the common vole (Microtus arvalis), and the greater white-toothed shrew (Crocidura russula)). The animals were caught at the former extraction site, in zones with three different levels of remediation treatments, and at a control site. Arsenic concentrations in the soil were highly spatially heterogeneous (ranging from 29 to 18,900 µg g(-1)). Despite the decrease in arsenic concentrations in the remediated soils, both wood mice and Algerian mice experienced higher oral exposure to arsenic in remediated zones than in the control area. The accumulated arsenic in their organs showed higher intra-zonal variability than the arsenic distribution in the soil, suggesting that, in addition to remediation processes, other variables can help explain arsenic transfer to wildlife, such as the habitat and diet preferences of the animals or their mobility. A weak but significant correlation between arsenic concentration and body condition was observed, and weak relationships between the liver/kidney/lung mass and arsenic levels were also detected, suggesting possible histological alterations.

Coupling of random amplified polymorphic DNA profiles analysis and high resolution capillary electrophoresis system for the assessment of chemical genotoxicity.

Cadmium (Cd) can be toxic to terrestrial snails, but few data are available about its genotoxic effects on early life stages (ELS). The aim of this study was to investigate the genotoxic potential of Cd in embryos of Helix aspersa using a new approach that couples Random Amplified Polymorphic DNA (RAPD) and a high-resolution capillary electrophoresis system (HRS). Clutches of H. aspersa were exposed to Cd solutions (2, 4, and 6 mg/L) from the beginning of their embryonic development. In addition to a dose-dependent effect of Cd on hatching rate, DNA fragmentation was observed in embryos that were exposed to 6 mg Cd/L. The analysis of RAPD products with HRS showed differences between the profiles of exposed and nonexposed embryos, starting at 2 mg Cd/L. In comparison to the profiles of the control samples, all profiles from the exposed snails exhibited an additional 270 bp DNA fragment and lacked a 450 bp DNA fragment. These profile modifications are related to the genotoxic effect of Cd on the ELS of H. aspersa . Our study demonstrates the efficacy of coupling RAPD and HRS for a rapid and efficient screening of the effects of chemicals on DNA.

Can Body Condition and Somatic Indices be Used to Evaluate Metal-Induced Stress in Wild Small Mammals?

Wildlife is exposed to natural (e.g., food availability and quality, parasitism) and anthropogenic stressors (e.g., habitat fragmentation, toxicants). Individual variables (e.g., age, gender) affect behaviour and physiology of animals. Together, these parameters can create both great inter-individual variations in health indicators and interpretation difficulties. We investigated the relevance of body condition and somatic indices (liver, kidneys) as indicators of health status in wood mice (Apodemus sylvaticus, n = 560) captured along a metal pollution gradient in four landscape types (30 sampling squares 500-m sided). The indices were calculated using a recently proposed standard major axis regression instead of an ordinary least square regression. After considering age and gender for the body condition index, no landscape type influence was detected in the indices. However, important index variability was observed between sampling squares; this effect was included as a random effect in linear models. After integrating all individual and environmental variables that may affect the indices, cadmium (Cd) concentrations in both the liver and kidneys were negatively related to body condition and liver indices only for individuals from highly contaminated sites. Lead in the liver was negatively related to the liver index, and Cd in kidneys was positively linked to the kidney index, potentially suggesting metal-induced stress. However, interpretation of these indices as a wildlife ecotoxicology tool should be performed with caution due to the sensitivity of potentially confounding variables (e.g., individual factors and environmental parameters).