Offre de thèse : IPHC-CNRS (STRASBOURG) AND THE INSTITUT COCHIN – INSB (PARIS)


DEADLINE: 30 JUNE 2020 for applications. A shortlist of 5 applicants will be established shortly and interviews realized in the first 15 days of July.

 

Same Mitochondria, Different Longevities: What Do Ants Tell Us About Metabolic Ageing? a Project Coupling Evolutionary Biology to Cellular Bioenergetics

 

Key-words : Ageing ; Evolution ; Mitochondria ; Bioenergetics ; Ants ; Proteomics ; Molecular biology

 

Ants offer an exciting scientific opportunity for the study of ageing processes since these animals have evolved a striking variability of longevities both among species but also within a species among different castes. Shorter lifespan should be associated with a faster progression of age-linked profiles of physiological traits.

 

In accordance, ants have been used in previous studies to evaluate how the accumulation of damages with age, antioxidant capacities or telomere dynamics may explain ants’ longevity, producing mixed support for the Reactive Oxygen Species or Disposable Soma theories. For example, queens do not show longer telomeres (a determinant of cell lifespan and individual survival) than short-lived workers (females), but do so with short-lived males, suggesting that beyond telomere length, additional cell signalling pathways may be of key importance in queen longevity determination. Energy metabolism and metabolic rate are also considered as essential components of the ageing equation with impact on longevity, shortly stated as « live fast die young ». Mitochondrion is by far the main energy provider for animal cells and also controls redox homeostasis including reactive oxygen generation/disposal.

 

The question is therefore if/how the longer longevity of certain castes/individuals is associated with biochemical/molecular differences that could be considered as causatives: mitochondrial efficiency, antioxidant levels or telomere dynamics. Are they modified when a worker role changes, switching her ageing phenotype from a low to a fast rate? This raises the question of the influence of social context on individual senescence? One requisite is to access to ant’s bioenergetics both at the level of individuals and of mitochondria. Methodological issues will need to be addressed, our first experiments showed that respiration of ants is detected in the high-resolution respirometer (O2k Oroboros instruments). In contrast, classical extraction protocols used on vertebrate organs/cells did not yield preparation in which the biochemical activity ant’s mitochondria could be measured. New protocols will have to be invented. We know how to deal with limiting the amount of starting material: the extremely sensitive luciferase reaction (luminescence) is used to monitor ATP production rate and flow cytometry to evaluate membrane potential or ROS generation at the level of single mitochondria. To complete the picture of mitochondrial-derived associated ageing signalling pathways (e.g. Bax/Bak, CytC, caspases…) proteomic experiments will be settled.

 

In this context, we want to develop a new research project in the emerging field of socio-bioenergetics, which unifies the co-evolution of social organization with ageing processes using bioenergetics and molecular methodologies.

 

The present PhD project addresses the evolutionary mystery of the « ant same mitochondria but astonishing different longevities within a species », by merging two teams with complementary skills and knowledge. The Ecology, Physiology and Ethology department of the Institut Pluridisciplinaire Hubert Curien will bring its knowledge in evolutionary trade-offs bases and mechanisms of ageing and its presently running ants’ captive colonies. The Physiology and Evolutionary Physiology team (http://www.iphc.cnrs.fr/-Ethologie-et-Physiologie-Evolutive-EPE-.html) focuses on how animals cope with trade-offs (physiology and behavioural mechanisms) and what are the fitness consequences (Evolution). This will be completed by the state-to-the-art bioenergetics approaches of the team Mitochondria, Bioenergetic, Metabolism and Signalization of the Institut Cochin (https://www.institutcochin.fr/la-recherche/emd/equipe-bouillaud).

 

Expected skills:

The PhD candidate will be shared by the IPHC and the Cochin Institute, with a consequent work using mitochondrial bioenergetics protocols which needs a substantial background in laboratory work. Thus, we are seeking for a student with a large background in energetics/molecular biology, who will be trained with evolutionary biology questioning and interpretation of the results. He will be based during the first year at the Cochin Institute (Paris), working under the supervision of Dr F Bouillaud, doing mainly methodological set-up devoted to the measurement of ants’ mitochondria bioenergetics. The second and third years are planned to be in Strasbourg, but schedule may change in relation to the project advancement.

 

Acquired expertise:

The PhD candidate will become an expert in:

– Bioenergetics applied to insects

– Evolutionary biology of ants

– Evolutionary biology theories of ageing

– Mixed models’ statistics

– Methodological skills: mitochondrial respiration methodology, qPCR, introduction in proteomics, statistics, scientific writing, project management, communication skills.

 

Salary:

The project is funded by a CNRS- Interdisciplinary Mission grant of 17 keuros for functioning and a PhD allowance of ca. 1700 euros (before taxes) per month for three years (2020-2023), starting next October. The PhD contract will provide access to the French social security. Possibilities of teaching at the University of Strasbourg are open, with substantial income gain. The PhD will be hosted by the doctoral school of the University of Strasbourg (ED 414), and then will have to fulfil all the training obligatory for each PhD (54h in total), mostly provided by the University (French lessons, animal care training, animal ethics…). The IPHC and Cochin research teams are friendly and international and non-French speaking applicants are welcome.

 

Contacts:

François Criscuolo, IPHC-CNRS, francois.criscuolo@iphc.cnrs.fr, http://www.iphc.cnrs.fr/-Ethologie-et-Physiologie-Evolutive-EPE-.html

Frédéric Bouillaud, Institut Cochin INSB-CNRS, frederic.bouillaud@inserm.fr, https://www.institutcochin.fr/la-recherche/emd/equipe-bouillaud

Fabrice Bertile, IPHC-CNRS, fbertile@unistra.fr, http://www.iphc.cnrs.fr/-Spectrometrie-de-Masse-BioOrganique-LSMBO-.html

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