hmmm
well, this forum seems to be filled with alot of people wanting to know stuff. So I guess I'll do my part, and inform yall. I actually have taked with a person who knew the person who discovered telomeres. Dr.Hayflick had this problem with these cells he was growing up for an experiment, after a certain time they would stop dividing. Anyway hes bitching about this at lunch with his fellow scientists, and one of them joking says that maybe the cells are going old. He meant it as a joke just to shut hayflick up, but hayflick didn't realize that it WAS a joke! So anyway thats how we got the hayflick limit, pretty neat.
Telomerease has been known about for many years, and it really is the problem of greater cell pluripotency or infinite life. Single cell organisms produce tons of telomerase, but with multicellular organisms its different. Here, I'll repost what I said earlier ...
I'm surprised there aren't many actually informed posts on this message forum, I guess I'll have to straighten the whole deal about aging. FYI I am exceptionally interested in aging research, I've read alot about it, I've been to very cool seminars, and I have a very positive outlook as to what the biogerontology field will be able to achive over the next 25 years.
Aging all started when sex evolved, by fusing gametes together two different individuals could create a new offspring instead of just dividing. Were we to reproduce by splitting into two, we would effectively be immortal. But we do not, and our multicellular bodies have through a billion years of evolution refined this whole reproduction thing.
In species that do reproduce by division, they have very high amounts of a protein called telomerase. This enzyme is key to setting the biological clock of any cell. At the end of each chromosome are caps called telomeres, every time a cell divides your telomeres get slightly shorter. With the cap deleted, genes on the edges of the chromosome start to loose nucleotides and eventually the cell no longer has the necessary genes to divide. When you have alot of telomerase your cells never reach this point, infact your telomeres stay the same length.
Now having immortal cells sounds like a good idea, but if your a multicellular being then *some* of your cells might malfunction. By having a set number of times a cell can divide, your body effectively limits the amount of damage a haywire cell can do. The whole deal about aging can be considered as a ying and yang of cancer versus youthfulness. Animals that have longer telomeres have greater chances of healing rapidly, but are more vulnerable to cancer. Mice are a perfect example, they have a great ability to heal however they are also about 60,000 times more succeptible to cancer then humans. The limit to our cells ability to divide is clearly shown with age, but our replicative limit can also be reached by other means. Professional Tri-athaletes are starting to experience significant muscle loss near the age of 45 because their store of muscle stem cells to repair muslce has been run too low because of overuse.
Mutations also play a roll in aging, the more defects in your genes the greater likely hood that even MORE mutations will accumulate. And there are ways for cells to get around the telomere cap problem, the gene to produce telomerase can be switched on and IS done so in many of the large cancers that are life threatening. However reducing the amount of mutations in a cell will only decrease the chances of cancer, and doing this doesn't work by taking anti-oxidants since the body already has its own ample supply.
So, how do we overcome aging? Well, several ways. First off there is a large movement to develope the technology to grow organs, if you slowly replace your body with younger parts before they wear out theres no real limit to how long you can live. Stem cells are also being discovered to be very ample at repairing parts of the body, and the idea of injecting new stem cells to repair old tissue is definetly possible. Any attempt to reverse aging will have to involve two major steps, resetting the telomerase clock, and checking for mutations. If they were going to grow you a new heart, the source cells to use for you would be screened for mutations. By starting the growth of a new organ with fewer mutations you will encounter less complications later on.
The most difficult organ to replace, would obviously be the brain. Simply put, you can't replace it! Already we have found embryonic stem cells can repair old brain damage, and using modified stem cells to rejuvinate the brain would be THE way to combate aging of our most important organ. Recently it was discovered that stem cells even in old age can migrate up to the brain and start creating new neurons. Stem cells as a whole, are KEY to combating aging. Embryonic stem cells are even better, because their cellular organelle are healtheir then the older mitochondria that exist in your own cells.
Cancer itself may be dealt with by creating new genes that are hypersensitive to mutations. Aging and our current situation makes perfect sense when held in the light of evolution. Back when we were hunter-gatherers and death happened ALOT we had evolved to live about 45ish, just long enough to properly raise our children and then die. Our bodies have a combination of cellular pluropotency(ability to heal, etc) and cancer rate that was ideal for our survival. Now had there been enough evolutionary pressure, genes would have evolved that allowed us to live far longer then 45 years but the key word is having *enough* pressure. Humans could evolve to grow purple wings if there was *enough* evolutionary pressure and time. Aging is a health problem, that like many other aspects of biology, is simply a compromise between various conflicting factors.
