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Tissues that keep dividing do not age; some cells that have been in culture for 40 years have long outlived their donors. It has been suggested by Alex Comfort of London University that aging is the result of a loss of cellular information during the life of the individual. This loss of cellular information may occur but does not explain the varying life-spans of different mammals. For example, if mice are starved, they live far longer than usual, and this is associated with the stress of continually foraging for food.
W. S. Bullough and his colleagues at Birkbeck College in London have shown that the cell division that replaces lost parts of the liver and skin is controlled by an antimitotic messenger molecule, or chalone, whose effect is increased by such stress hormones as adrenaline. Chalones are thought to act at two points in the cell cycle—the time of cell division, which produces the new functional cells, and the time of cell death, which removes the older cells. Different cells have different natural lives, but all are gradually killed off by the chalones—for example, 10,000 nerve cells are lost per day during adult life. Death of the animal occurs when insufficient vital nerve, skeletal, or muscle cells are left.
Thus, aging can be delayed by stress, which reduces the rate at which the chalones destroy vital cells. Professor Bullough — perhaps tongue in cheek—pointed out that laughter is as much a stress as tears.
W. S. Bullough and his colleagues at Birkbeck College in London have shown that the cell division that replaces lost parts of the liver and skin is controlled by an antimitotic messenger molecule, or chalone, whose effect is increased by such stress hormones as adrenaline. Chalones are thought to act at two points in the cell cycle—the time of cell division, which produces the new functional cells, and the time of cell death, which removes the older cells. Different cells have different natural lives, but all are gradually killed off by the chalones—for example, 10,000 nerve cells are lost per day during adult life. Death of the animal occurs when insufficient vital nerve, skeletal, or muscle cells are left.
Thus, aging can be delayed by stress, which reduces the rate at which the chalones destroy vital cells. Professor Bullough — perhaps tongue in cheek—pointed out that laughter is as much a stress as tears.
