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BBC NEWS / SCIENCE/NATURE

Eighty million years without sex

The mystery of how an animal has survived for 80 million years without sex
has been solved by UK scientists.

A Cambridge team says the creature owes its existence to a genetic quirk
that offers some recompense for its prolonged celibacy.

Many asexual organisms have died out because they cannot adapt to changes in
the natural world.

But an evolutionary trick allows this pond-dweller to survive when
conditions change, researchers report in Science.

"There could be some benefit to millions of years without sex after all"
Dr Alan Tunnacliffe, University of Cambridge

The animal is a tiny invertebrate known as a bdelloid rotifer. It lives in
freshwater pools. If deprived of water, it survives in a desiccated state
until water becomes available again.

The secret to this novel survival mechanism lies in a twist of asexual
reproduction, whereby the animal is able to make two separate proteins from
two different copies of a key gene.


Prolonged celibacy


Dr Alan Tunnacliffe, from the Institute of Biotechnology at the University
of Cambridge, who led the research, said his team had been able to show for
the first time that gene copies in asexual animals can have different
functions.

"It's particularly exciting that we've found different, but complementary,
functions in genes which help bdelloid rotifers survive desiccation," he
explained.

"Evolution of gene function in this way can't happen in sexual organisms,
which means there could be some benefit to millions of years without sex
after all."

The researchers discovered that two copies of a particular gene, known as
LEA, in the asexual pond-dweller are different - giving rise to proteins
with separate functions that protect the animal during dehydration.

One copy stops other essential protein molecules from clumping together as
the animal dries out, while the second copy helps to maintain the fragile
membranes that surround the creature's cells.


Joe Umstead

"Joe Umstead" wrote in message ...

The mystery of how an animal has survived for 80 million years without sex
has been solved by UK scientists.

That's very interesting, but not very relevant to yeast, as far as I can figure
out.

As far as yeast is concerned, some strains are capable of sexual reproduction,
probably not including bread yeasts. In those yeast strains capable of sexual
reproduction, certain conditions, which may include drying, and the presence
of complementary mating strains, are involved. Spores are the product of
sexual reproduction. Spores are resistant to adverse conditions, including
drying, but come to life and start reproducing in the usual way (by budding)
when conditions are right.

If you don't believe me, do a search on sexual reproduction in yeast.

--
Dicky

I am resisting the ufge to rename this thread alt.sex.yeast