"Disposable Soma" Theory of Aging

Hangjun Chang iam at CHOLLIAN.DACOM.CO.KR
Thu Jul 25 04:05:29 EST 1996


Hi! Dear Friends who are interested in aging mechanism all around world. 
Today, I want to talk about the *disposable soma * theory.
I have though over the connection between aging process and reproduction 
for a long time. In virtue of the *diposable soma* theory, I*ve got many 
insights into aging process.  Many aging researches are focused on the 
cellular or molecular level of aging process.  I want to see aging 
process in the level of organism. In that point, the theories of 
evolution of aging are helpful to me.

According to the *disposable soma theory* because of the requirement for 
reproduction, natural selection favors a strategy that invests fewer 
resources in maintenance of somatic cells and tissues than are necessary 
for indefinite survival. This beautiful hypothesis are based on the fact 
that both somatic maintenance and reproduction require energy. 
This theory predicts that aging is due to the accumulation of unrepaired
somatic defects and the primary genetic control of longevity operates 
through selection to raise or lower the investment in basic cellular 
maintenance systems in relation to the level of environment hazard. 
This theory also proposes that a high level of accuracy is maintained in
immortal germ line cells,  or alternatively, that any defective germ 
cells are eliminated. More interestingly, some taoists in ancient China 
avoided their reproductive activities in order to save energy, in their 
terms, 'Ki', turning it into making their body young as long as 
possible. 

I have several questions on the *disposable soma * theory

1.  If this theory is true, early castrated animals must live more 
    longer period than do non-castrated animals because early castration 
    abolishes the energy demands for reproduction, turning some extra- 
    energy back into the use for the body maintenance. I think it is the 
    most simplest way to test this hypothesis. 
    Is there any evidence to support the early castration effect on 
    life extension in animals or even in humans?

2.  How much energy do the gametogenesis require over the entire life
    of that organism? How does reproductive demands for energy compete 
    with that of body maintenance and repair? 
    In other words, for what life resources is such a competition made? 

3.  Is there any  aging control gene that might be a coordinate 
    regulator of a range of stress response genes that shift cellular 
    physiology toward maintenance? In a recent issue .of Science, 
    Gordon J. Lithgow et al. suggest that age-1 may be such a candidate 
    because age-1 mutant strains of C. elegans are better equipped than 
    their wild type counterparts to overcome the effects of extrinsic 
    stress, such as better resistance to oxidative stress and fewer     
    deletions of the mitochodrial genomes.  
    I am thinking over the epigenetic control of such a gene to stop 
    aging process. I am eager to know what signals or factors in blood 
    can activate longevity assuring pathways in metabolism. 

4.  Is it true that higher accuracy is maintained in immortal germ 
    line cells than do somatic cells? 

5.  Is there any evidence or opinion that sex hormones have some effects 
    on aging process?


I am looking forward to people who are very kind enough 
to answer my questions :)

Thanks for reading my post.

Hangjun Chang M.D.
iam at chollian.dacom.co.kr 





 
 
 
 
  
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