Metabolic Flexibility and Suspended Animation
Our work in suspended animation derives from the fact that many animals exhibit what we call "metabolic flexibility," the ability to dial down their respiration and heartbeat and, in effect, "turn themselves off" in response to physical or environmental stress. Mammalian examples include hibernation — from ground squirrels to bears — as well as estivation (quiescence in response to heat) and embryonic diapause, a pause in embryonic development found in about 70 species of mammals. Meanwhile, many invertebrates can go dormant for days, months, and even years before reanimating. Finally, germ and somatic stem cells are well known to exit the cell cycle for extended periods of time and to re-enter only when it is favorable for the organism.
Our approach to understanding this flexibility has been to develop the means to stop animals for given periods of time and then reanimate them to normal function. We use the term suspended animation to refer to a state where all observable life processes (using high resolution light microscopy) are stopped: the animals do not move nor breathe and the heart does not beat. We have found that we are able to put a number of animals (yeast, nematodes, drosophila, frogs, and zebrafish) into a state of suspended animation for up to 24 hours through one basic technique: reducing the concentration of oxygen.
By examining the precise oxygen tensions needed to induce suspended animation, we also found discrete and lethal oxygen tensions exist just above the oxygen level that enables suspended animation. In other words, there is a range of oxygen levels that is too low to support life, but going below that causes the animals to suspend. We hypothesized that perhaps we could prevent death in low oxygen situations by adding agents that effectively inhibit oxygen utilization and induce suspended animation.
Copyright © 2003-2013 Molecular & Cellular Biology Program, University of Washington
Fred Hutchison Cancer Research Center | University of Washington
Institute for Systems Biology | Seattle Biomed