main content

Prof. Anthony Poole, University of Auckland (NZ): Experimental evolution sheds insights on the intracellular lifestyle

Speaker Series. Abstract: Intracellularity leads to some quite unusual changes to genomes and to nucleotide metabolism. I will present the results of two studies that make use of experimental evolution for to examine the evolution of two phenomena. In the first project, I will present work from our lab on the impact of knocking out genes for ribonucleotide reduction in the bacterium E. coli. We document the dependence of these bacteria on externally-supplied deoxyribonucleosides, mimicking the loss of this process in some intracellular bacterial species, including Ureaplasma, Borrelia and Buchnera. Our experiment revealed subsequent gene losses that were also found to have naturally occurred in these species. The paradox we observed was that the gene losses that emerged following loss of ribonucleotide reduction prevented the potential for evolution to make use of an alternative mechanism for dNTP synthesis, suggesting that a short term benefit trumps the long term potential in this system. The second project involves the serial bottlenecking of E. coli to see whether genetic drift hastens the emergence of genomic errors that can be corrected via slippage (during) or via editing (after) transcription. Such processes are quite common in intracellular bacteria such as Buchnera, but also are found in eukaryotic organelles of bacterial origin. Our results show that, under conditions favouring genetic drift, we do indeed observe an increased probability of the evolution of these processes. We conclude that our experiments support the idea of constructive neutral evolution, a process by which genetic drift leads to more complex molecular processes with no immediate advantage. In both cases, the ancestral state did not require the capacity for slippage or editing, but, at the end of the experiment, loss of such processes would unmask sublethal mutations - the genomes must now be corrected during gene expression to avoid this.

Veranstaltungsdaten

The Poole lab is primarily interested in molecular evolution, particularly of early life, early genomes and of the eukaryote cell. They use both experimental and computational approaches in their work. 

Prof. Poole will be available for meetings with other researchers. Please contact Marcus Lechner if you wish to speak with him.