What regulates the ageing process?

[AlexmBIOSS]

Hello,
I had a discussion last night that I was not sure how to develop fully. There are some species of Turltes which live for 255 years and some that live substantially less, The sturgeon fish http://en.wikipedia.org/wiki/Sturgeon" live extremely long outlasting tons of other fish, some species of trees can be only slightly different from relatives but live an order of magnitude longer.
So my question is: Is it a combination of environment and genetics that changes the life span through the ageing process? (you cannot change the environment without altering the ageing process so factors like food etc come largely into play in a very sensitive condition set) Or is it almost purely genetic? And I can't find literature for the gene list and difference. I would love to find out which genes are different between species that age differently.

The wikipedia article http://en.wikipedia.org/wiki/Senescence" has some references to genes but it is general and not specific to the organism relatives which is more interesting.

Best wishes to all,
Alex

 

[jim mcnamara]

One of the factors in ageing is Epigenetics - the change/damage DNA experiences during an organism's lifespan.

http://www.pbs.org/wgbh/nova/genes/issa.html

 

[Sorry!]

I'm not sure but it also has to do with the required energy the organism needs to live its life and how fast the organism grows. The cells of a turtle do not divide very fast and turtles require relatively little energy to continue to live. They can for extended periods of time even with food or water.

Cell division in humans occurs much faster and we require greater amounts of energy to live.

 

[Anti]

Like the other posters point out, there are a LOT of factors that go into determining how an organism ages; or better yet, if the organism ages well.

One aspect of our genetics that is of great importance to the aging process are our telomeres - repeating pieces of "junk" DNA at the end of our chromosomes that serve to protect DNA from replicative damage.

When your DNA replicates, the process results in an uneven "clipping" of the ends of the DNA that actually shortens the length of the strand. The telomeres help ensure that "essential" DNA isn't getting clipped - in fact, cells will stop replicating entirely before they reach a point that would damage DNA. Telomeres can be thought of essentially as buffers that guard your DNA.

So, if you have short telomeres, cell replication stops after fewer divisions. If you have long telomeres, it takes longer for the same thing to occur.

Of course, as with everything in biology, it isn't this simple.

There is an enzyme called Telomerase that repairs telomeres. You can have short telomeres and effective telomerase and protect your DNA for a lot longer than someone with long telomeres and ineffective telomerase.

This is but one process that contributes to aging but it's a very key component to the process and a lot of scientists are trying to figure out how feasible it is to use telomerase to extend lives.

 

[qedprigmosyno]

Note however that there is a very fine line for the telomeres, for if a cell abuses the telomerase, it becomes a cancer cell.

 

[farful]

Clearly the death executioner gene ( http://www.ncbi.nlm.nih.gov/UniGene/clust.cgi?ORG=Dm&CID=1719 ) is responsible for all deaths.

On a more serious note, you should read http://en.wikipedia.org/wiki/Metabolic_theory_of_ecology

a small portion of it:
"Small animals tend to grow fast, breed early, and die young. According to MTE, these patterns in life history traits are constrained by metabolism. An organisms’ metabolic rate determines its rate of food consumption, which in turn determines its rate of growth. This increased growth rate produces trade-offs that accelerate senescence. For example, metabolic processes produce free radicals as a by-product of energy production. These in turn cause damage at the cellular level, which promotes senescence and ultimately death. Selection favors organisms which best propagate given these constraints, so as a result smaller, shorter lived organisms tend to reproduce earlier in their life histories."

 

[whome9]

There is a built-in lifespan for humans, which is ~85. The book The Rectangular Curve discusses this.