Microscopic animals held algae captive and stole their genes for energy
production millions of years ago, reveals a new study.
Microscopic animals held algae
captive and stole their genes for energy production millions of years ago,
reveals a new study.
The study, published this week in
the journal Nature, reveals a ‘missing link’ in evolution, where
tiny protozoa frozen in time captured algal genes for photosynthesis – the
process of harnessing light to produce energy which is used by all plants and
algae on earth.
Until now, the international team
led by researchers from Dalhousie University in Canada had suspected that
quantum leaps of evolution occurred by one organism cannibalizing another, but
had insufficient evidence to prove this hypothesis.
But when they looked at two
specific algae – Guillardia theta and Bigelowiella
natans – the team realized the evolution was not quite complete. They
could see that their cells had two nuclei, which is unusual because plant and
animal cells only have one.
“We think that the genes for
photosynthesis originally evolved only once about three billion years ago. So
all plants, algae, and blue green bacteria can produce their own energy from
light because they have acquired these genes for photosynthesis,” said
Professor McFadden from the University of Melbourne, a co-author on the study.
Like prisoners in Alcatraz, the
captive algae appear to have been nurtured by their enslavers and the precious sugars
produced from photosynthesis became a vital part of the protozoan slave
keeper’s diet.
The captives lived inside the
protozoan cell and, under the right conditions, the pair gradually became
unified as a single organism – a process called endosymbiosis, which literally
means living inside each other.
“We discovered that the captors
were initially able to keep many separate clones of their slaves and
occasionally pillage one or two for most of the essential genes. However, at
some point in time, the number of captives reduced inside each gaoler to just
one individual,” McFadden said.
“So if they broke into the alga’s
cell to steal the last essential genes, they would destroy it in the process
and would not then be able to use the genes to run photosynthesis. So the two
cells, one captive and one captor, had apparently reached an evolutionary
stand-off situation where both are dependent on each other to survive,” he
said.
The article can be found at: Curtis BA et al. (2012) Algal
genomes reveal evolutionary mosaicism and the fate of nucleomorphs.
Source: University
of Melbourne
No comments:
Post a Comment