April 08, 2009 -- New genome sequence information from the humble baker's yeast has
revealed surprising variation in a set of genes that can be thought of
as nature's oldest clock. In a paper published in Genome Research
scientists show how ribosomal RNA genes that are essential to all
Earth's organisms provide insight into how genomes maintain their
integrity on their evolutionary journey.
RNA sequence changes have been ticking away like clockwork for over 3
billion years, maybe even pre-dating the origin of the DNA world
itself. However, even the slightest changes in sequence of these genes
can be fatal. It is vital to conserve the important genetic 'cogs' to
make sure cells function correctly. However, significant changes do
occur, contrary to expectation, and yet the yeast somehow still
Furthermore, when two yeasts hybridise the clocks appear to re-set,
apparently overwriting each others' rhythm and eliminating unwanted
variations on the theme. This provides clues as to how key motifs are
conserved and allows us to track the evolutionary history of hybrids.
James, lead researcher at the Institute of Food Research (IFR), said "I
have sequenced these genes to selectively identify yeast species for
over 15 years and had no idea they would turn out to be so variable."
Davey, computational biologist at the National Collection of Yeast
Cultures (NCYC), said "we can use new computer techniques to model the
changes mathematically and really get to grips with what orchestrates
the variation in these important cell housekeepers."
Roberts, Curator of NCYC, said "Yeasts are everywhere around us in
nature and industry. This extra level of detail allows us to resolve
important differences between yeasts and gain maximum benefits from
their use in food, drink and healthcare."
Source : Norwich BioScience Institutes