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Antoine Frénoy - Postdoc in microbial evolution

I am currently a postdoc with Eduardo Rocha (Microbial Evolutionary Genomics) at Institut Pasteur, discovering the wonderful world of bioinformatics.

Before this I was a postdoc with Sebastian Bonhoeffer (Theoretical Biology) at ETH Zurich, working mainly on stress-response, evolvability and robustness in bacteria (read our recent publication here).

And before I was a PhD student with François Taddei and Dusan Misevic (INSERM U1001). My PhD focused on the links between second order selection and evolution of cooperation, using both microbial and in silico systems (some of our work here and here).

Email address

antoine DOT frenoy AT pasteur DOT fr

Research

Increased evolvability under stress: stress-induced mutagenesis and death

Stress-induced mutagenesis (SIM) has been a major paradigm shift in the past decades: it postulates that as an answer to stress, bacteria increase their genome-wide mutation rate. This has been interpreted as a mechanism providing “adaptation on demand” (increased evolvability under stress, increasing the chances that a descendant is able to face the stress)

In our recent paper (Frenoy & Bonhoeffer, 2018, PLoS Biology), we challenge this view by showing that (1) current methods lead to a systematic over-estimation of mutation rate under bactericidal stress, and (2) a stress that increases mutation rate does not always increases evolvability.

Evolution of cooperation and second-order selection pressures

Because genes coding for cooperation (here public good secretion) face very different selection pressures than more classical genes coding for private traits (affecting only the individual bearing them), we wondered whether they would somehow evolve different genetic properties.

To answer this question, we adapted the Aevol platform to the study of cooperation by implementing a spatial structure and the potential to secrete a public good. Aevol is an individual-based model that has a bacterial-inspired genomic layer and is has been used to study second-order selection pressures acting on genome organization.

We found (Frénoy et al, 2013, PLoS Computational Biology) that genes related to cooperation (coding for secretion of a public good) tend to spontaneously form operons (using the same promoters and terminators) and overlap (using the same base pairs but in different reading frames) with “metabolic” (only contributing to the focal individual's private fitness in our vocabulary) genes. A large part of “cheating” (decreasing secretion) mutations are thus also impacting “private” genes, causing a drop in fitness and the mutation being wiped out by selection.

We interpret this as an example of evolvability suppression (evolution of a trait constraining futur evolution). Several recent studies show the potential relevance of this kind of second order selection pressures on cooperation in microbial world [Foster et al, 2004, Nature and Dandekar et al, 2012, Science] and beyond [Altenberg, 2005, Artificial Life].

Curriculum Vitae

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