Scientific background. Anthropogenic activities linked to industrialisation, agricultural development, transport intensification and urbanization, are responsible for worldwide emissions and accumulation of various chemical pollutants, in particular heavy metals [1]. Although they are naturally occurring elements, heavy metals can impair various biological functions, including immunity, reproduction or endocrine regulation, even at low exposure levels [2]. While numerous studies have reported on the toxicity of heavy metals, their role as an emerging evolutionary pressure remains to be addressed. Particular emphasis should be given to the effects of heavy metals exposure on physiological traits, especially those that reflect changes in condition and health over the life course.

Objectives and hypotheses. This project aims at investigating whether exposure to heavy metal speeds up the rate of biological ageing in a long-lived mammal, the European roe deer (Capreolus capreolus), and to test whether the underlying mechanisms involve redox homeostasis disruption. To this end, the candidate will benefit from longitudinal data from two roe deer populations in France (Trois-Fontaines and Chizé forests), which have been monitored for more than 40 years, and which inhabit contrasted habitats in terms of ecological conditions. Contamination profiles for metal trace elements (e.g. As, Pb, Hg, Cd, Cu, Zn, Mn, Fe, Ni, Cr) will be connected to various measures of the oxidative balance (via plasma levels of oxidative stress markers and antioxidants molecules). Biological age will be quantified using two molecular markers whose relevance has been demonstrated very recently in roe deer: the telomere length (i.e. the protective caps at the ends of chromosomes) [3] and the epigenetic age acceleration (i.e. the difference between DNA methylation-predicted age and chronological age) [4], both measured from leucocyte DNA.
Although recent studies suggested that pollution can have an impact on each of these variables [5–8], no study so far has attempted to integrate them all. This project aims at filling this gap.

Project scheme and expectations. Data on heavy metal and most of the physiological data are already available for 200-300 individuals that were captured and sampled between 2016 and 2018. Oxidative stress biomarkers (encompassing both oxidative damages and antioxidant defences molecules) are to be assayed during the internship. The candidate will be in charge of (1) conducting the oxidative stress assays, (2) compiling all data into a comprehensive dataset and (3) analysing the data with appropriate statistical tools (e.g. linear models, path analyses). Motivation to work in the lab and skills for data analysis, preferably using R, are strongly expected. Any experience in one or in both of these fields will be an asset.

Contacts : Pauline Vuarin (pauline.vuarin@univ-lyon1.fr), Benjamin Rey (benjamin.rey@univ-lyon1.fr) or Jean-François Lemaitre (jean-françois.lemaitre@univ-lyon1.fr), Laboratoire de Biométrie et Biologie Evolutive – UMR CNRS 5558, Université Claude Bernard Lyon 1. To apply, please send us your CV, a motivation letter and a transcript of marks from your master degree.

References

1. Gavrilescu M, Demnerova K, Aamand J, Agathos S, Fava F. 2014 Emerging pollutants in the environment: present and future challenges in biomonitoring, ecological risks and bioremediation. N. Biotechnol. 00, 1–10.
2. Tchounwou PB, Yedjou CG, Patlolla AK, Sutton DJ. 2012 Heavy metals toxicity and the environment. Mol. Clin. Environ. Toxicol. 101, 133–164. (doi:10.1007/978-3-7643-8340-4)
3. Wilbourn R V et al. 2017 Age-dependent associations between telomere length and environmental conditions in roe deer. Biol. Lett. 13, 20170434.
4. Lemaître JF et al. 2020 Epigenetic clock and DNA methylation studies of roe deer in the wild. bioRxiv , 2020.09.21.306613.
5. Isaksson C. 2010 Pollution and its impact on wild animals: A meta-analysis on oxidative stress. Ecohealth 7, 342–350. (doi:10.1007/s10393-010-0345-7)
6. Hoxha M et al. 2009 Association between leukocyte telomere shortening and exposure to traffic pollution: a cross-sectional study on traffic officers and indoor office workers. Environ. Heal. 8. (doi:10.1186/1476-069x-8-41)
7. Nilsen FM et al. 2016 Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis). Sci. Total Environ. 545–546, 389–397. (doi:10.1016/j.scitotenv.2015.12.059)
8. Stauffer J, Panda B, Eeva T, Rainio M, Ilmonen P. 2017 Telomere damage and redox status alterations in free-living passerines exposed to metals. Sci. Total Environ. 575, 841–848. (doi:10.1016/j.scitotenv.2016.09.131)

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