Cellular
Communications  |
Slime moulds
organize some astonishing get togethers with
a communication system derived from their
bacteria ancestors.
Because cells are much larger than bacteria,
biologists have investigated slime mould communications
since 1933.
Discoveries about slime moulds
communications have provided important clues
on the mystery of how more complex creatures
coordinate their development from an egg to
a multicellular organism.
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Other slime mould amoebae detect the AMP and follow the scent to join forces with the troubled amoebae. In addition to
stimulating a follow the leader attitude, AMP also excites those that detect it into
making and releasing their own AMP. So, as the amoebae stream together, they
generate more signals drawing an ever growing crowd. AMP is an important chemical word in
the language of cells and seems to be understood and made by all cells, even our
own. |
 When the amoebae converge, they mound together. When the mound reaches a
critical size, it plops over on its side and becomes a small slug-like creature made of
about 100,000 cells. |
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 Getting under way
The slug looks and acts like a multicellular organism. It creeps
through the forest soil for three to four days, leaving a slimy trail behind it. The slime
trail not only gives slime moulds their popular name, it also lubricates the forward
motion of the slug. When the slug finds a place with the correct environmental parameters,
it undergoes a second remarkable transformation. |
Moving through time
The cells forming the nose and primitive skin of the slug migrate into new
positions and duties. Some become a basal disk and attach the whole group to the forest
floor. Others organize themselves into a long hollow stalk that towers into the air as
much as 5-millimeters above the forest floor. All in all, about 30 percent of the amoebae
that formed the slug reorganize into a plant-like fruiting body.
The other 70 percent, those from the posterior inner portion of the
slug, squeeze up the hollow stalk their friends make with their bodies and stuff
themselves into the upper end of the tube, forming a bulb-shaped capsule. Each cell curls
up to make as much room as possible in the bulb and secretes a thick wall of cellulose
around itself. The resulting spoor can, it is said, withstand extreme environmental
conditions for months, perhaps years. They can be frozen solid or baked dry and still
survive. |
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Space Cadets
After the spores settle into place, some of the amoebae forming the capsule
seal off the spores from the rest of the hollow stalk. Then, the amoebae making the stalk
wall pump oxygen into the sealed hollow space. When the pressure exceeds a certain level
the capsule ruptures and the spores are blasted into the air to be carried by the wind to
new destinations. |
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There are lots of good examples of the amazing
communication skills of cells, but the slime moulds hold a special fascination because of
the remarkable transformation of free living creatures into a single, organized
multicellular concept. And the final ejaculation at the end of the cycle reminds me,
somehow, of our human effort to blast people, and ideas, off into space.
For more information about how cells communicate to form larger and
larger creatures, explore the communication web of the living
corals.
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floor or pseudopoding
through rotting wood - until their food or water 
begins to dwindle. 
