PARIS — Astronauts aboard the International Space
Station are set to welcome a most unusual guest, as "the Blob" blasts
off into orbit on Tuesday.
اضافة اعلان
An alien on its own planet, the Blob
is an unclassifiable organism – neither fish nor fowl. Nor is it plant, animal
or fungus.
As such, Physarum polycephalum — a
type of slime mold — has long fascinated scientists and will now be part of a
unique experiment carried out simultaneously by
astronauts hundreds of kilometers
above the Earth and by hundreds of thousands of French school students.
The slime mold first appeared on Earth
around 500 million years ago and defies conventional biology because it is made
up of one cell with multiple nuclei.
While most organisms grow and
reproduce through the division and multiplication of cells, Physarum
polycephalum does not.
"It is a single cell that grows
without ever dividing," explains Pierre Ferrand, professor of Earth
sciences and life seconded to French space agency CNES, one of the people
behind the project.
Another oddity: "When most
organisms make do with two sex types, the Blob has more than 720.
It is an
organism 'with drawers' which tells us that life consists of multitude
originalities," he says.
What one's cell can do
A yellowish, spongy mass, the slime mold
lacks a mouth, legs or brain.
Yet despite these apparent
disadvantages, the mold eats, grows, moves — albeit very slowly — and has
amazing learning abilities.
Because the Blob's DNA floats freely
around inside its cell walls — rather than being contained inside a nucleus —
it can "slough off" parts of itself at will.
It can also enter a dormant state by
dehydrating — called "sclerotia."
And it is several pieces of sclerotia
that will embark on their odyssey aboard an ISS refueling freighter.
When rehydrated in September, four
sclerotia — each about the size of the average pinky fingernail — will be
roused from their torpor in their Petri-dish beds.
The samples — both shorn from the same
"parent Blob cell" (labeled by scientists as LU352) — will undergo
two protocols: one will deprive certain sub-Blobs of food; the others will be
able to gorge out on a food source — porridge oats.
The goal is to observe the effects of
weightlessness on this organism — but as an educational experience, a giant
school experiment that reaches into space.
There are no scientific papers
expected as part of the mission's design.
"Nobody knows what its behavior
will be in a microgravity environment: What direction will it move in? Will it
take the third dimension by going upwards, or go sideways?" asks Ferrand.
"I'll be curious to see if it
develops by forming pillars," says Blob specialist Audrey Dussutour,
director for the Centre for Research on Animal Cognition in Toulouse.
Meanwhile, back on Earth, thousands of
specimens cut from the same LU352 strain will be distributed to about 4,500
schools and colleges in France.
"More than 350,000 students will
'touch' the Blob," says Christine Correcher, who runs the space agency's
educational program.
At the end of this month, teachers
will receive kits containing three to five sclerotia.
When the sections of the Blob are
revived in space, their cohorts will also be
rehydrated on Earth.
Observations will then begin to
compare the differences in how the samples in space adapt compared with those
on Earth — which may cast light on fundamental questions surrounding the basic
building blocks of life.
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Science and Technology
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