Roxane Moritz

Environmental regulation of ICEclc transfer in Pseudomonas

I work on an integrative and conjugative element (ICEclc) that confers on its bacterial host the ability to degrade 3-chlorobenzoate (CBA). ICEclc can also transfer its DNA from one host cell to a new recipient, but does so only in small proportion of cells. The main goal of my project is to better understand the conditions and possible trigger(s) that initiate this process of transfer in individual cells. One of the hypotheses is that ICEclc has evolved to escape individual cells that are in bad physiological shape in order to transfer and survive in a hopefully healthier cell. I am developing methods to record the life history of individual cells during population growth, cell division and differentiation. I work with time-lapse microscopy and automize procedures to recognize cells on images, trace back cell lineages and quantify fluorescent reporter signals that are indicative for the behaviour of the ICE or the host cell state. I have developed systems to follow oxidative stress in individual growing cells and to measure variations in the stationary phase sigma factor, which we suspect play a role in linking host cell physiology to ICE activation.