*Experiments on “slime mold” explain why almost all multicellular organisms begin life as a single cell*
Any multicellular animal, from a blue whale to a human being, poses a special challenge for evolution.
Most of the cells in its body will die without reproducing; only a privileged few will pass their genes to the next generation.
How could the extreme degree of cooperation required by multicellular existence actually evolve? Why aren’t all creatures unicellular individualists determined to pass on their own genes? (more…)
*Cells at the tip of the slime mold’s fruiting body organize into an epithelial layer and secrete proteins as do some animals cells*
The so-called cellular slime mold, a unicellular organism that may transition into a multicellular organism under stress, has just been found to have a tissue structure that was previously thought to exist only in more sophisticated animals. What’s more, two proteins that are needed by the slime mold to form this structure are similar to those that perform the same function in more sophistical animals.
Shortly after an animal embryo forms, it develops a single layer of cells that, shaped like a hollow ball, is empty at its center. Acting as a kind of “man behind the curtain” that directs these cells to organize into this hollow formation are several proteins that help each cell touch its neighbors but keep its top surface exposed to the formation’s empty interior. (more…)
