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Genetic differences between yeasts greater than those between humans and chimpanzees

University of Gothenburg

The mapping of the entire yeast genome in 1996 marked the beginning of a revolution in biological and medical research. The human genome was mapped in 2001, and by now the number of characterised species is approaching 1000, most of which are bacteria. The next advance is only a few years away - mapping the genetic evolution of individual multicellular animals, including humans.

"We shall then be able to identify the genetic causes of human disease and to understand how the process of evolution works when species are being formed," says Anders Blomberg, professor at the Department of Cell and Molecular Biology, University of Gothenburg.

Anders Blomberg and his colleague Jonas Warringer are publishing a paper in the highly respected scientific journal Nature, that to some extent leads to a new era in evolutionary and functional genetics research. The lowly yeast is, once again, leading the way.

In collaboration with the Sanger Institute in Cambridge, and the University of Nottingham, the Gothenburg researchers have succeeded in sequencing the DNA and characterising the genome properties (i.e. phenotypes) of 70 different individual organisms from two different species of yeast - the common brewer's yeast Saccharomyces cerevisiae and its evolutionary cousin Saccharomyces paradoxus. The paper presents several interesting conclusions, e.g. that human alcohol consumption has altered yeast DNA.

"As humans transported wine and beer yeasts around the world, different yeasts have mated and recombined, so that the strains of today carry gene variants from various parts of the world. This mosaic pattern is not at all visible in our studies of another yeast that has not been exploited by humans," says Anders Blomberg.

The study also shows that there can be greater genetic differences between individuals within a particular species of yeast than there are between humans and chimpanzees. The DNA of individual yeast organisms can vary by up to 4 per cent, compared to the 1 per cent difference between the DNA of humans and chimpanzees. Another interesting observation is that individual organisms from the same species can have extra genetic material. Most of these "extra genes" occur at the periphery of the chromosome (the telomer region), which lends support to the theory that these areas are very important in evolution.

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