The aim of this project is to assess the risk of emergence of Bacillus cereus strains with higher virulence to mammals and to test the hypothesis that stresses experienced by B.cereus within the insect guts might trigger some genomic differentiation that could allow a subset of the bacterial population to adapt to this new niche and possibly become more virulent/pathogenic. It also aims at and at understanding how quickly this species evolves in natural conditions, what constrains that rate and what evolutionary mechanisms it uses for adaptation and evolution.
The goal is to set up large-scale laboratory experiments where the evolution is simulated with fluctuating selective pressures. The experiments will be designed to study the genomic adaptations that this species may face in nature. The insect digestive tract will be used as an environmental model of bacterial adaptation and as a selection medium to select novel pathogenic strains. The approach relies on a model system, consisting of B. cereus and the insect Galleria mellonella larvae as a host, which are both ideally suited to experimental analysis. The principle will be to set up a serial passage experiment of B. cereus in the insect, to select more virulent bacterial strains and study how they have evolved. Emphasis will be put on comparative whole genome analysis of multiple evolved strains (or lineages) and in understanding how different life traits evolve in different conditions. The mechanisms of such adaptations will also be traced in relation with plasmid transfer and phage development. Experiments will also be designed to determine how temperature can influence the induction of adaptation mechanisms in the insect digestive tract, including transfer of genetic material, through plasmids or bacteriophages. Integration of the genomic and phenotypic data, using computational approaches, should then allow us to explain phenotypic differences in terms of genotypic differences. An examination of how the genomes and phenotypes of the evolved strains have changed will also permit to identify the selective pressures they have experienced and how this is related to fitness improvement.
A postdoctoral position will be available to work at the INRA center of Jouy en Josas (7 km east of Versailles) with a 2400 € appointment (raw salary) per month. The contract could start at any time from March-April 2013. The appointee will be based in the Micalis laboratory within Didier Lereclus’ group and will be part of the ANR “PathoBactEvol” project which includes six French academic partners and two European teams. The project is essentially an academic research project and most of the results are expected to be of fundamental interest; the main awaited outcome is therefore increasing our knowledge on bacterial mechanisms of evolution.
The candidate will be in charge of establishing a powerful and versatile model for analysing the causes and processes of evolutionary adaptation, including direct observation of evolution in action and under fluctuating conditions. He will also participate in the analysis of the genomic sequence data generated using novel high throughput sequencing technologies (NGS) to provide the data necessary to describe the complete set of genes implicated in these adaptation processes.
Candidates for this position should hold a PhD degree in microbial ecology and/or evolutionary biology or related disciplines. Additional skills in genomics, applied mathematics and/or in using bioinformatic tools will be an advantage. An evolutionary biologist and a keen experimentator with a capacity to hold a productive dialog with computer specialists would be the ideal candidate.
Applications should include a cover letter, a curriculum vitae, a list of publications, a brief summary of research experience and interest, and the names of (at least) two referees. Applications will only be accepted by e-mail and should be sent to Vincent Sanchis. E-mail: vincent.sanchis@jouy.inra.fr
0 comentários:
Postar um comentário