The Mechanisms and Evolution of Senescence in Microbes (Ref: 3985)

Senescence, the accumulation of biomolecular damage leading to age-related declines in reproduction and survival, is pervasive across the animal kingdom and has become a key focus of research in evolutionary biology and biomedicine. It has long been thought that unicellular organisms typically do not senesce, because without a clear germ-soma divide any damage accumulated by one generation would be passed to the next, leading to the progressive deterioration and ultimate extinction of the lineage. However, the advent of high resolution live-imaging techniques that allow researchers to track the life-histories of individual cells and lineages within clonal E. coli populations has revealed evidence of clearly structured variation in both reproduction and survival among cells, now widely interpreted as evidence that bacteria do senesce. This discovery has triggered a surge of interest in the possibility of bacterial senescence, both among evolutionary biologists and applied microbiologists. This project will combine cutting-edge microbiology with experimental evolution to critically assess whether this complex phenotype does indeed show the key hallmarks of senescence. The project will have two main strands. First, we will couple high resolution live-imaging of dividing cell lineages with novel fluorescent markers to experimentally test whether variation in performance arises via damage accumulation or novel alternative mechanisms. Second, we will develop evolutionary models of microbial senescence, to investigate whether the true pattern of variation in cellular performance is consistent with what one would expect of senescence. This ambitious project is expected to significantly advance our understanding of senescence in microbes and shed new light on the evolutionary origin of senescence.