Philippe Remigi: The evolution of phenotypic heterogeneity in Pseudomonas fluorescens
- Date: Apr 24, 2018
- Time: 11:00 AM - 12:00 PM (Local Time Germany)
- Speaker: Philippe Remigi from Massey University, New Zealand
- Please find more information on Philippe Remigi here: http://evolution.massey.ac.nz/philippe.html
- Location: MPI Plön
- Room: Lecture hall
- Host: Paul Rainey
Abstract:
Observations
of bacteria at the single-cell level have revealed many
instances of phenotypic heterogeneity within otherwise clonal
populations, but the selective causes, molecular bases and
broader ecological relevance of these phenomena remain poorly
understood. In an earlier experiment in which the bacterium Pseudomonas fluorescens SBW25 was propagated under a
selective regime that mimicked the host immune response, a
genotype evolved that stochastically switched between
capsulation states. The genetic cause was a mutation that
decreased the pool of intracellular pyrimidine metabolites
(and growth rate), lowering the activation threshold of a
pre-existing but hitherto unrecognised phenotypic switch. Here
I will describe our recent efforts to understand the molecular
mechanisms responsible for the bistable expression of
extracellular capsules. This work led us to realise that,
in the ancestral bacterium, the switch is part of a programme
that determines stochastic entry into the semi-quiescent
capsulated state, but also enables these cells to exit rapidly
from stationary phase under permissive conditions.