Description du sujet de thèse

Exploring the roles seasonal telomere changes in underlying life-history trade-offs and fitness in hibernating ground squirrels.
This PhD project will investigate the links between seasonal telomere dynamics, telomere maintenance processes, and fitness in a hibernating rodent, the Columbian ground squirrel (Urocitellus columbianus).

Contexte de travail

The PhD will be attached to the « Ecole Doctorale Vie et Santé » of the University of Strasbourg (ED414).
Understanding the cellular mechanisms implicated in the process of ageing has been the focus of evolutionary biologists for decades. Telomeres – and more specifically telomere shortening or elongation rates – have been identified as key components of the aging process. Telomeres are non-coding genomic DNA sequences located at the end of linear chromosomes, whose primary role is thought to prevent the loss of genomic function by allowing the genomic rescue system to distinguish chromosome ends from accidental DNA breaks. However, telomere sequences are highly sensitive to oxidative stress and imperfectly replicated at each cell division, resulting in progressive erosion over time. Until recently, telomeres were seen as a hallmark of ageing, progressively shortening over time until cell apoptosis or senescence. The loss of telomere functionality has been correlated to the accelerated aging process. However, current data shows that cellular telomeres can be rejuvenated even in adult tissues, owing to maintenance mechanisms including telomerase activity (a ribonucleoprotein specialized in rebuilding telomeres) and/or alternative telomere lengthening through recombination (ALT) processes. Interestingly, several recent studies suggest that hibernating mammals may actually be able to restore cellular telomere length on a seasonal basis, but the mechanisms implicated in these dynamic changes (telomerase activity or ALT, or both) remain untested. In addition, how such changes are related to organism age and fitness remain unknown.

Our previous research has found that these animals show dynamics patterns of telomere reconstruction following hibernation and loss over the summer breeding season. The candidate will be responsible for determining the mechanisms responsible for these dynamics, determining the inter and intra-individual variability in telomere length and telomere elongation processes and how these relate to life history traits, and determining the links between telomere length, telomere elongation processes and fitness. To do so, they will benefit from samples already collected in the field and from a long-term life history data base providing information on individual age, reproductive success, past breeding experience. Existing samples will be complemented by novel collections during fieldwork over the course of the PhD (the candidate is expected to participate in at least two 3-month-long field campaigns in the Rocky Mountains of Canada). The tasks will thus include :
(1) laboratory analyses of samples to determine telomere length, telomerase activity, DNA instability biomarkers related to telomere dysfunction, and markers of DNA damage by oxidative stress;
(2) participation in 3-month long field sessions aimed at long-term population monitoring and data collection;
(3) statistical analyses of inter- and intra-individual variability in telomere maintenance and relations to fitness.
The successful applicant will be based at the Institut Pluridisciplinaire Hubert Curien in Strasbourg (Department of Ecology, Physiology and Ethology DEPE) and co-supervised by Dr Vincent A Viblanc and Dr François Criscuolo, but the candidate will perform part of laboratory work at Cell Environment, Genopole Evry in Paris under the supervision of Dr. Radhia M'Kacher. The DEPE is a lively Department where the student will benefit from interaction with a thriving community of postgraduate students, postdocs and researchers in animal physiology, ecology and behaviour. Furthermore, the student will integrate a larger international research endeavor with opportunities to interact with researchers from Canada, and various labs in France including the IPHC-DSA (Strasbourg), LIENSs (La Rochelle) and LPC (Caen), building a multidisciplinary culture from evolutionary ecology to proteomics, physics and cancer biology. The student will participate in the PhD program of the Doctoral School ED414 of the University of Strasbourg (http://ed.vie-sante.unistra.fr/) providing additional learning of transferable skills.
Strasbourg is one of Europe's most attractive cities. It has a rich historical and architectural heritage, with Strasbourg's historical city center being listed as a World Heritage Site by UNESCO. Its human size, its pedestrian city center and 500 km of cycling paths make it a very pleasant city to wander around. Vibrant and affordable, Strasbourg is a true student city providing a great learning and living environment (Check out the New York Time's video: 36 Hours in Strasbourg).
Requirements:
- Master in sciences in evolutionary ecology, physiological ecology, molecular ecology
strong quantitative, statistical and programming skills (good knowledge of R required)
- Good laboratory skills (ELISA, DNA extraction, PCR)
- Independent, mobile, creative, highly motivated, and has interest in animal physiology and behavioural and evolutionary ecology
- Good English level both oral and written at level B2 according to the Common European Framework of Reference for Languages to interact with all project partners and transfer results in scientific publications and presentations at conferences.

Due to the multidisciplinary and collaborative nature of the work, we are looking for a highly motivated and curious candidate, which can both work as part of a team and show autonomy.

Contraintes et risques

Field work in Canada (two or three 3-month periods) in a natural environment. This work occurs on weekends and can occur out of normal working hours.

Informations complémentaires

Candidates should send a resume and cover letter, as well as a summary of their masters and associated master grades. Please provide the contact details and a reference letter from one to two independent references.