From DNA to the Canterbury Tales
Cambridge & Great Eastern Regional Group: Evening science lecture Cambridge University, UK
 The Cambridge & Great Eastern Regional Group was treated to a fascinating, wide-ranging lecture on DNA and what can be learned from mistakes on 12 October 2005.
Chris Howe, evolutionary geneticist, of the biochemistry department, University of Cambridge, started with the story of DNA in algae and chloroplasts, and explained the use of transcription error analysis to track molecular evolution. The accumulation of mutations in DNA sequences over a billion years can be used to trace early events in the evolution of cells that gave rise to structures such as mitochondria and chloroplasts. This produces some surprising conclusions, for example that the malaria parasite has a photosynthetic ancestry.
Chloroplasts possess their own genome, which is a remnant of the genome of the photosynthetic bacteria from which they evolved by endosymbiosis. The chloroplast genome typically contains 120 or more genes on a single molecule. However, in dinoflagellates (the algae that cause toxic red tides), the chloroplast genome seems to have disintegrated. Most of the genes have been lost to the nucleus, and the few that remain are located on small circles of around 3 kilobase pairs (kbp), most of which carry only a single gene. Howe’s research is aimed at understanding how this extraordinary organelle genome is maintained and controlled, how the genes that have moved to the nucleus are organised, why organelle genes should move to the nucleus, and how it happens.
‘The capacity to blunder slightly is the real marvel of DNA. Without this special attribute, we would still be anaerobic bacteria and there would be no music’
Lewis Thomas (1913-93) |
Howe then explained how his group applied the iochemical algorithms they had developed to analyse phylogenetic trees, to the stemmatic analysis of the evolution of medieval manuscripts. There are striking parallels between how mutations accumulate in DNA sequences as they evolve and how changes were incorporated into manuscripts when they were copied by scribes in the days before printing. In a novel interdisciplinary collaboration with manuscript scholars around the world, Howe’s research group is applying the techniques of molecular evolutionary biology to the analysis of a range of texts, from the Bible to Chaucer’s Canterbury Tales. Not surprisingly, this extraordinary interdisciplinary leap has ruffled some academic feathers, but the results appear to speak for themselves.
A stimulating and elegant lecture, which vividly portrayed the intimate interconnectedness of things.
By John Wilkins
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Cambridge & Great Eastern Regional Group
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