Summarised from a story by Bob Holmes, entitled 'Shrimps challenge meaning of life', in New Scientist.
Research into the dormant state which brine shrimps are able to go into under adverse conditions, is prompting scientists to revise their basic definition of life itself. It is axiomatic in biology that life will always involve some minimal level of metabolic activity. Even in conditions of dormancy like hibernation, cells will always need to produce some energy to prevent decay. Not so the brine shrimp.
In hard times, when they are deprived of oxygen, brine shrimps form a resistant cyst, within which they shut down their metabolism more or less completely. They cannot be said to die, because when oxygen is restored - even four years later - the shrimps emerge from their cysts alive and well.
James Clegg, a comparative biochemist at the University of California's Bodega Marine Laboratory, has studied this most unexpected life cycle very closely. The failure of the dormant shrimps to register any discernible metabolic activity even under his most minute laboratory scrutiny, has defied one of the basic rules of biological science. Under these fully hydrated conditions, the shrimps would have been expected to deteriorate, if not expending any energy on making proteins to maintain its cell structures. Deteriorate, however, they did not.
"If you can't measure the metabolic activity you associate with life, it makes you start thinking about how to define living versus dead," says Steven Hand, a biochemist at the University of Colorado. "We may want to reconsider defining life as just the maintenance of structure."
Clegg's hypothesis is that the answer to the conundrum may lie in what are known as 'chaperone' proteins. These proteins, which are found in some dormant embryos, can bind to other proteins and protect them from damage. Their presence in the mysterious brine shrimp, however, has yet to be proved.
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