What is it with Conifers?Oldest living organisms,oldest seed producers,been around...

[dr.syntax]

around 230 million years. To this day covering more land mass than any other plant group. As JillSwift pointed out in another thread some of these trees live to be over 5,000 years old. The Giant Redwood and the Bristlecone Pine. How on Earth did certain individual plants that cannot move or change thier location manage to survive all the droughts,fires,insect infestations,microbial infection, and such for 5,000 years. More importantly why don`t they deteriorate the same way other organisms do with age? Maybe under the right conditions they are potentially immortal. What is about them that seems to defie all the usual explanations for aging. The same may be true for some of the longest lived animals. Certain tortoises and turtles. Some sharks. Some of the oldest species having the longest lives. Looking for answers. ...Dr.Syntax ... Post Script: The : Encyclopedia of Britannica says conifers first appeared between 359 million to 299 million years ago. The World Wide catastophic events that occurred over those many eons boggles my mind. There is some discrepency as to what were the earliest seed producers. May not have been conifers.

Edited September 15, 2009 by dr.syntax
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[StringJunky]

I found this abstract which goes some way to explain the longevity of trees:

 

"A long life multiplies a tree's reproductive opportunities, thus increasing its fitness. Therefore, characteristics that prolong life should be naturally selected. Longevity in trees is achieved by means of numerous behaviors and characteristics, some of which are unique to trees. These include the retention of stem-cell-like meristematic cells after each growth cycle; the ability to replace non-vigorous, lost, or damaged organs, both above and below ground, in the presence or absence of trauma; a sectored vascular system that allows part of a tree to survive where a whole one cannot; formation of clones; a mechanical structure that can react to forces tending to de-optimize it; a hormonal control system that coordinates the above behaviors; and synthesis of defensive compounds."

 

http://www.ncbi.nlm.nih.gov/pubmed/12362893

 

Meristematic cells are like animal stem cells, found at the growth points, that are undifferentiated and can grow in to any cell required at the time...a great survival tactic!

 

As an example, if a tree gets burnt down parts of the rootball, below ground, will have these meristematic cells and will turn into a new apical (central leader) stem which becomes a new tree above the ground.

[dr.syntax]

I found this abstract which goes some way to explain the longevity of trees:

 

"A long life multiplies a tree's reproductive opportunities, thus increasing its fitness. Therefore, characteristics that prolong life should be naturally selected. Longevity in trees is achieved by means of numerous behaviors and characteristics, some of which are unique to trees. These include the retention of stem-cell-like meristematic cells after each growth cycle; the ability to replace non-vigorous, lost, or damaged organs, both above and below ground, in the presence or absence of trauma; a sectored vascular system that allows part of a tree to survive where a whole one cannot; formation of clones; a mechanical structure that can react to forces tending to de-optimize it; a hormonal control system that coordinates the above behaviors; and synthesis of defensive compounds."

 

http://www.ncbi.nlm.nih.gov/pubmed/12362893

 

Meristematic cells are like animal stem cells, found at the growth points, that are undifferentiated and can grow in to any cell required at the time...a great survival tactic!

 

As an example, if a tree gets burnt down parts of the rootball, below ground, will have these meristematic cells and will turn into a new apical (central leader) stem which becomes a new tree above the ground.

 

I`ve been wondering just how is it thier DNA does not deteriate like ours and most other organisms do. That stuff about meristematic cells being like animal stem cells seems a big part of the answer. These are important research topics. Wouldn`t it be nice to have such a system as a part of our makeup. Thank for this informative answer. ...Dr.Syntax

[StringJunky]

QUOTE=dr.syntax;514629]I`ve been wondering just how is it thier DNA does not deteriate like ours and most other organisms do. That stuff about meristematic cells being like animal stem cells seems a big part of the answer. These are important research topics. Wouldn`t it be nice to have such a system as a part of our makeup. Thank for this informative answer. ...Dr.Syntax

 

When a DNA molecule divides, it is making a copy of itself. Their is an upper limit to the number of times that the information encoded in it can be transferred through each successive generation, before pathological (life threatening) effects begin to occur, due to the original information becoming corrupted ie each successive division results in a small part of the DNA molecule being incompletely copied and ,hence, the 'instructions' slowly fade with time.

 

An analogy (parallel example) to this process would be to take a photograph, and photograph that photograph and so on. Eventually, details (information) would start to disappear.

 

My guess is that the rate at which cell division occurs in long-lived trees is much slower than in shorter-lived organisms, and as a result, takes longer to reach the aforementioned upper limit. Also, don't forget, things like Giant Redwoods have long periods of dormancy in winter when cellular activity is low....a kind of suspended animation!

 

The way these trees utilise aptosis (programmed cell death) may also be a factor in their longevity, but I don't know much about this, When the leaves fall in the Autumn is an example of this, but it also occurs at the single-cell level e.g. when a cell's DNA becomes damaged, it can self-destruct via specialized internal machinery.

 

Our liver has the ability to regenerate back to full size even if you lose up to 75% of it...this may be a function of stem cells:

 

" One of the defining features of the liver is the capacity to maintain a constant size despite injury. Although the precise molecular signals involved in the maintenance of liver size are not completely known, it is clear that the liver delicately balances regeneration with overgrowth. Mammals, for example, can survive surgical removal of up to 75% of the total liver mass. Within 1 week after liver resection, the total number of liver cells is restored. Moreover, liver overgrowth can be induced by a variety of signals, including hepatocyte growth factor or peroxisome proliferators; the liver quickly returns to its normal size when the proliferative signal is removed. The extent to which liver stem cells mediate liver regeneration has been hotly debated. .................................."

John P. Lynch and David C. Metz, Section Editors

 

http://www.gastrojournal.org/article/S0016-5085(09)00818-X/abstract

 

As far as I know, the liver is the only organ in our body that has this plant-like ability to regrow itself.

 

It would be great if the major parts of our bodies could regenerate themselves, like the liver , but it would greatly exacerbate the burgeoning population problem if our lifespan was increased to that of a Giant Redwood!

Edited September 16, 2009 by StringJunky

[dr.syntax]

is capable of rejuvenating itself also. I recall that every cell in the liver is replaced about every year or so. Something I ran across recently in an article describes bone marrow as a source of stem cells in adult humans . A well documented case of a woman who had her trachea recreated from stem cells taken from her own bone marrow is available on the web. She was 30 years old when this was done. So there is a usable source of our own stem cells in our own bodies. I don`t have a link for you. But you can google : woman`s own stem cells used to replace trachea. The article should pop up with a picture of her. There was no signs of scarring around her neck. One of the doctors claimed they would be able to do the same with a human heart within 20 years. Pretty exiting stuff. I found a link to that article and it is : http:http://www.cnn.com/2008/HEALTH/11/19/windpipe.transplant/index.html . It is a short read and pretty exciting when you consider all that such an accomplishment implies. ...Dr.Syntax

Edited September 16, 2009 by dr.syntax
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[GDG]

When a DNA molecule divides, it is making a copy of itself. Their is an upper limit to the number of times that the information encoded in it can be transferred through each successive generation, before pathological (life threatening) effects begin to occur, due to the original information becoming corrupted ie each successive division results in a small part of the DNA molecule being incompletely copied and ,hence, the 'instructions' slowly fade with time.

 

What you are probably thinking of is the telomere problem. The end of each DNA molecule in a chromosome has a special repeating sequence of bases called a telomere that is added by an enzyme (telomerase). With each time the chromosome is replicated, a number of repeats are lost (not copied) at each end. After a number of cell divisions (and thus chromosome replications), you run out of telomere repeats, and start losing parts of the genes at the ends of the chromosomes. Eventually you accumulate enough damage that the cell division cycle halts, and the cell apoptoses.

 

Telomerase operates in your germ cells and stem cells: once your stem cells differentiate away from their pluripotent form, the countdown timer starts ticking... Telomerase also functions in certain other cells, but we usually call those "tumors"...

 

Cells that express telomerase can continue replicating essentially forever, as in the case of immortalized cell lines.

[dr.syntax]

Thank your for that informative response, So if liver cells and bone marrow cells contain stem cells, is it at least in the realm of possibilities that with further research we may some day be able to grow a new kidney or event a heart ? Keep in mind that case of that woman who had a new trachea created using her own bone marrow. It seems it is already being done to some degree. Specically that woman`s trachea. It appears to me we are beyond the verge of this sort of stem cell organ repair/replacement. It is a short read if you haven`t yet read it. Here is the link again: http:http://www.cnn.com/2008/HEALTH/11/19/windpipe.transplant/index.html . Thanks for your interest, ...Dr.Syntax

Edited September 17, 2009 by dr.syntax
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[granpa]

Maybe under the right conditions they are potentially immortal. What is about them that seems to defie all the usual explanations for aging. The same may be true for some of the longest lived animals. Certain tortoises and turtles. Some sharks.

 

the trouble with these plants and animals is that they continue to grow throughout their lives. if they were immortal then they would eventually become too big to survive

[dr.syntax]

the trouble with these plants and animals is that they continue to grow throughout their lives. if they were immortal then they would eventually become too big to survive

 

when these giant redwoods fall over perhaps from becoming too tall, they still manage to live on. Some of their branchs become new trees. When this fact is taken into account the age of some of these trees has been estimated to be as much as 30,000 years,possibly more. Truly amazing organisms. I appreciate your interest. ...Dr.Syntax

Edited September 18, 2009 by dr.syntax
spelling

[StringJunky]

What you are probably thinking of is the telomere problem. The end of each DNA molecule in a chromosome has a special repeating sequence of bases called a telomere that is added by an enzyme (telomerase). With each time the chromosome is replicated, a number of repeats are lost (not copied) at each end. After a number of cell divisions (and thus chromosome replications), you run out of telomere repeats, and start losing parts of the genes at the ends of the chromosomes. Eventually you accumulate enough damage that the cell division cycle halts, and the cell apoptoses.

 

Telomerase operates in your germ cells and stem cells: once your stem cells differentiate away from their pluripotent form, the countdown timer starts ticking... Telomerase also functions in certain other cells, but we usually call those "tumors"...

 

Cells that express telomerase can continue replicating essentially forever, as in the case of immortalized cell lines.

 

Thanks for that GDG. With your words, I checked out to see if the action of telomerase occured in trees and as luck would have it, it does. The authors of this research suggest it may help to explain the longevity of trees like the Bristlecone Pine. Abstract here:

 

" Normal somatic cells have a finite replicative capacity. With each cell division, telomeres (the physical ends of linear chromosomes) progressively shorten until they reach a critical length, at which point the cells enter replicative senescence. Some cells maintain telomere length by the action of the telomerase enzyme. The bristlecone pine, Pinus longaeva, is the oldest known living eukaryotic organism, with the oldest on record turning 4770 years old in 2005. To determine what changes occur, if any, in telomere length and telomerase activity with age, and what roles, if any, telomere length and telomerase activity may play in contributing to the increased life-span and longevity of P. longaeva with age, as well as in other tree species of various life-spans, we undertook a detailed investigation of telomere length and telomerase activity in such trees. The results from this study support the hypothesis that both increased telomere length and telomerase activity may directly/indirectly contribute to the increased life-span and longevity evident in long-lived pine trees (2000-5000 year life-spans) compared to medium-lived (400-500 year life-span) and short-lived (100-200 year life-span) pine trees, as well as in P. longaeva with age."

 

http://www.ncbi.nlm.nih.gov/pubmed/16034678