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Re: Peter Parsons in Biogerontology





on 10/3/02 10:21 AM, Jacobus, John (NIH/OD/ORS) at jacobusj@ors.od.nih.gov

wrote:



> Jim,

> I guess this goes back to the old joke about the need to pick your parents

> to get the best genes.

> 

> I notice they do not identify radiation has a useful stressor to increase

> lifespan.  



Funny. In English it says exactly that! But then you never read anything.

 

> -- John 

> John Jacobus, MS

> Certified Health Physicist

> 3050 Traymore Lane

> Bowie, MD  20715-2024

> 

> E-mail:  jenday1@email.msn.com (H)

> 

> -----Original Message-----

> From: Muckerheide [mailto:muckerheide@attbi.com]

> Sent: Tuesday, October 01, 2002 7:27 AM

> To: radsafe@list.vanderbilt.edu

> Subject: Peter Parsons in Biogerontology

> 

> 

> Friends,

> 

> Our friend Peter Parsons has published the following paper.

> 

> Regards, Jim Muckerheide

> Radiation, Science, and Health

> ===============================

> 

> Biogerontology 2002;3(4):233-41

> 

> Life span: does the limit to survival depend upon metabolic efficiency

> under stress?

> 

> Parsons PA.

> La Trobe University, Bundoora, Vic. 3083, Australia; Author for

> correspondence: P.O. Box 906, Unley, SA 5061, Australia (e-mail:

> pparsons@senet.com.au; fax: +61-8-8373-5557)

> 

> Survival to old age in natural populations is enhanced by high vitality

> and resilience which depends upon substantial homeostasis and energetic

> and metabolic efficiency underlain by genes for stress resistance. Under

> this assumption increased longevity follows from primary selection for

> stress resistance where stress targets energy carriers. Furthermore old

> and young fitness should be correlated irrespective of age under the

> stressful selection regime of natural populations. In contrast,

> antagonistic pleiotropy is most likely under the less rigorous selection

> regime of well-nourished humans and laboratory populations surviving to

> old age. Similarly, hormesis for longevity, for example from a mild

> temperature stress or restricted food intake is most likely under benign

> environmental conditions. Assuming that aging in natural populations

> depends upon ecological circumstances, large evolutionary increases in

> life span are unlikely under the stress theory of aging since organisms

> are frequently close to their limits of survival where metabolic

> efficiency is at a premium. Exceptions can occur in island populations

> and for mutants under laboratory conditions since the risks from

> environmental hazards are reduced, and life span becomes extended as a

> consequence. In modern human populations, selection for stress

> resistance is less intense than in earlier times which should be

> permissive of the accumulation of stress-sensitive mutants under the

> mutation-accumulation theory of aging. However, this process is

> ultimately likely to restrict the evolution of life-span extensions in

> the future especially if abiotic conditions deteriorate, when survival

> would depend more directly on metabolic efficiency under stress.

> 

> http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list

> _uids=12232505&dopt=Abstract

> 

> 

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