Past projects

Age-associated phenotypes of budding yeast

with Gregory Paul, Peter Horvath, Yves Barral.

Even in unicellular species such as bacteria and yeasts, systematic effects can be observed as time passes or as cells undergo consecutive divisions. This has been proposed to be a relevant model to study senescence and indeed constitutes a fascinating case of phenotypic variability. I focused on bringing together the knowledge of molecular mechanisms involved in increased longevity and the implications of senescence on population dynamics and life history strategies. However, a comprehensive framework is still missing to understand the evolutionary origins and implications of senescence in microbes.

Denoth Lippuner A, Julou T & Barral Y (2014) FEMS Microbiol. Rev. 38, 300–325.

Public goods dynamics in clonal populations of bacteria

with Nicolas Desprat, Thierry Mora, David Bensimon, Vincent Croquette.

While interested in the dynamics of siderophore producers and non-producers in spatially structured environments, we discovered that there is a large variability of siderophore abundance between producer cells in a clonal population. We characterised the temporal dynamics of siderophore abundance in details and showed that rapid exchanges between neighbouring cells support the astonishingly large variability.

Julou T, Mora T, et al. (2013) Proc. Natl. Acad. Sci. U.S.A. 110, 12577–12582.

Monitoring microbial population size at low density

with Vincent Croquette, Nicolas Desprat, David Bensimon.

Using the fluctuations of scattered light to measure the abundance of bacteria and yeasts at low concentration; this was initially meant to be a detection device for the project of experimental evolution in a spatially structured environment, and has been completed and published independently.

Julou T, et al. (2012) Rev Sci Instrum 83, 74301.

Experimental evolution in a spatially structured environment

with Nicolas Desprat, Vincent Croquette, David Bensimon.

A sustained attempt to evolve motile bacteria in a double gradient of temperature and nutrients. By maintaining a temperature gradient from 30 to 60ºC and delivering nutrients at the top, we aimed at studying adaptation in a structured environment; since the sensitivity to temperature is a complex trait that depends on the history, this is also a promising setup to study the interplay between physiological acclimation and genetic adaptation. This project was hindered by practical constraints as explained in details in my PhD thesis.