Mobile DNA and the evolution of horizontal gene transfer
Not only can genes pass between parents and offspring (vertical transmission) but in a number of organisms, they can also be transferred horizontally. In bacteria, such horizontal gene transfer can come about through three processes: transfer through bacterial viruses (known as transduction), the uptake of DNA from the environment (known as transformation) and transfer through cell-to-cell contact, such as transfer of genes on plasmids (known as conjugation). In many pathogenic bacteria, it appears that genes involved in virulence and anti-biotic resistance are carried on plasmids, and hence can be transferred horizontally. This raises the question as to why this is so, and why doesn't the cell keep these genes if they are beneficial. Additionally, plasmids (which are circular extra-chromosomal pieces of DNA) often incur costs on their hosts. Our research addresses how plasmids may persist, why they carry the traits they do, and why, if costly, evolution hasn't selected for host to eliminate plasmids.
We ask the following questions:
- As mobile DNA is costly, can it ever bring about the extinction of host populations?
- What type of genes will evolve to be carried on plasmids? How does this affect antibiotic resistance or the virulence of pathogenic bacteria?
- Can horizontal-gene transfer promote cooperation between micro-organisms?
- Svara, F. & Rankin, D.J. (2011) The evolution of plasmid-carried antibiotic resistance. BMC Evolutionary Biology. 11: 130.
- Mc Ginty, S., Rankin, D.J. & Brown, S.P. (2011) Horizontal gene
transfer and the evolution of bacterial cooperation. Evolution. 65: 21-32.
- Rankin, D.J., Rocha, E.P.C. & Brown, S.P. (2011) What traits are carried on mobile elements and why? Heredity. 106: 1-10.
- Rankin, D.J., Bichsel, M. & Wagner, A. (2010) Mobile DNA can drive lineage extinction in prokaryotic populations. Journal of Evolutionary Biology. 23: 2422-2341.
- Nogueira, T., Rankin, D.J., Touchon, M., Taddei, F., Brown, S.P. & Rocha, E.P.C. (2009) Horizontal gene transfer of the secretome drives the evolution of bacterial cooperation and virulence. Current Biology. 19: 1683-1691.