Research Interests
As free-living cells adapt to their environment, they regulate a large portion of their genome. Genome-wide responses have been measured for a variety of environmental challenges, each showing a regulation of most cellular functions, from metabolism to cell cycle and signaling. For example, a shift in ambient temperature is a frequent and inescapable environmental challenge for most free-living cells, and one which affects the very chemistry biological processes are based on. For instance, it is well-known that species have an "optimal temperature" – usually lower than the maximal tolerable temperature – where growth is fastest. By measuring protein expression levels in S. Cerevisiae over a temperature range of 15C, I am studying how this optimal growth state is characterized, and how cells adapt away from this optimum. More generally, I will study how cellular functions, such as signaling, are affected by temperature shifts and the ensuing variation of chemical reaction rates. It is possible that many functions are temperature compensated at the level of network structure.
The cells' responses to environmental challenges are the evolutionary result of specific selective pressures but also of the overlap between cellular responses to different environments. We assume some overlap is caused by the cell having few environment-sensing mechanisms, and is thus inevitable. As a consequence, if a given cellular circuit has two different functionalities, they would evolve at the same time – in parallel – since in any given cell both functionalities are needed. Using models of simple cellular functions, I am studying how such constraints affect evolution.