Aestivation in African lungfishes: Physiology, biochemistry and molecular biology.

Abstract

Suspended animation has long fascinated scientists because of its great application potentials in fields ranging from medicine to space travel. Animals become inactive during suspended animation, with absolutely no intake of food and water, and hence producing minimal or no urine and faecal materials, for an extended period. They enter into a state of torpor, possibly slowing down the biological time in relation to the clock time. If suspended animation can be achieved in humans, surgeons would have more time to operate on patients during critical moments when the blood circulation stops, and the dream of long distance space travel can be realized. In nature, suspended animation is expressed in some adult animals undergoing hibernation or aestivation. ‘Aestivation’ is a loose term that signifies little more than an animal undergoing a state of torpor to survive arid conditions (except for aquatic aestivators like certain sponges and sea cucumbers) at high temperature, in many cases during summer. The term has been used to describe the listless state of endotherms, like ground squirrels and cactus mouse at the height of summer heat, and ectotherms, like amphibians and African lungfishes that make cocoons to encase themselves for weeks to more than a year during the hot dry season.