Worm Breeder's Gazette 8(1): 15
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Transient blocking of development produces a coordinate halt in the aging process. We have blocked development of larvae at several distinct times in larval growth, still using starvation to block development. We find that larvae survive starvation for periods up to two weeks. Little mortality is seen before 5 days in typical experiments. The survivors of the starvation period can resume immediate development when returned to growth conditions and still have normal adult life-spans. This is all consistent with the idea that the 'aging clock' (if we can coin that phrase) doesn't really begin until development's clock has ended or that development and aging both respond to the same clock. These observations fit in well with a body of information in the aging literature dealing with the phenomenon of 'caloric restriction'. This is-a regimen of systematic underfeeding, typically at 60% of what ad libitum fed controls would eat; this regimen has been shown to prolong life-span in a variety of different organisms and is currently being studied as a possible means of intervention into human aging. We would like to try and test the model that there is a separate aging clock by asking if this clock may have properties different from the developmental clock. One difference could be that the aging clock may not be stopped by starvation in adults, after the developmental clock has finished. In trying to test this notion using N2, we discovered that L4's will complete development under the starvation regimen and turn into bags. All fecund adult stages respond similarly. As a matter of fact, there appears to be a critical stage of larval development at about the time of the L3 to L4 molt at which time a developing worm becomes 'committed' to the completion of development independently of the amount of food that the larva is given. We're currently determining what this critical stage is. We get around the bag problem by using temperature-sensitive embryonic lethals to block development of embryos within the bodies of starving mothers and ask if starvation has a similar effect at other times of life. The results of these experiments are still unclear but it is apparent that there are significant differences in the response of life-span to starvation in adults as compared with the response of life-span to starvation in larvae. We're still worried about possible selection that we may be artificially imposing on the population of animals that survive the starvation protocol and therefore are looking for less drastic ways to block development. If anyone knows of some technique which can arrest development and is still reversible after a period of at least a few days we'd appreciate knowing about it. We've tried using accumulator mutants (mutants that are arrested in larval development) from the Hirsh collection but an extensive although not exhaustive search of those stocks failed to yield any that were readily reversible after extended growth under the non-permissive conditions.