(PhysOrg.com) -- Humans might not be walking the face of the Earth were it not for the ancient fusing of two prokaryotes -- tiny life forms that do not have a cellular nucleus. UCLA molecular biologist James A. Lake reports important new insights about prokaryotes and the evolution of life in the Aug. 20 advance online edition of the journal Nature.
Endosymbiosis refers to a cell living within another cell. If the cells live together long enough, they will exchange genes; they merge but often keep their own cell membranes and sometimes their own genomes.
Lake has discovered the first exclusively prokaryote endosymbiosis. All other known endosymbioses have involved a eukaryote — a cell that contains a nucleus. Eukaryotes are found in all multicellular forms of life, including humans, animals and plants.
"This relationship resulted in a totally different type of life on Earth," said Lake, a UCLA distinguished professor of molecular, cell and developmental biology and of human genetics. "We thought eukaryotes always needed to be present to do it, but we were wrong."
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