Do you think cloning can help save various species?

[shakeybrainsurgeon]

The problem with a lack of genetic variability has nothing to do with a general lack of adaptation or a lack of mutations. It has to do with the precise role of transplantation antigens in the immune response to pathogens. Those protein markers that define our "tissue type" for organ transplantation are intimately involved with processing foreign molecules. Because we all have a different tissue type, we all have a unique repertoire of immune reactions. Thus, a certain segment of the population will, by chance, have an inborn talent for recognizing a virus, even if it has never seen it before. That's why no plague or virus can ever wipe out a genetically diverse population. The need for a diverse immune repertoire is the reason why two people can't trade organs.

Animals that survive a bottle neck and are genetically homogenous can still survive so long as some infection that they can't deal with arises (example of a disaster: the cheetah and feline leukemia virus). In other words, if they are lucky, they can survive.

Eventually, over dozens of generations, the tissue antigen variability returns due to gene rearrangements that occur naturally in these genes.

(Apologies to ThatsSomeBadHatHarry, who made the same point earlier --- I was commenting on DrBill's point about genetic diversity and future adaptation)

 

[ThatsSomeBadHatHarry]

I meant to respond to DrBill, the post immediately after yours that says that genetic diversity is required to adapt. Genetic diversity isn't required to adapt over time, i don't believe, it's required to resist massive disease outbreaks in the here and now, which, as you note, is the same point you made.

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[shakeybrainsurgeon]

Cloning has one additional problem: premature aging. There are two types of cells; somatic (body) cells and germ cell (sperm, egg). The chromosomes of somatic cells, but not germ cells (or cancer cells), have some modification after each cell division. In a sense, the cell carves a notch of its chromosomes after each division. After a certain number (I think 40 is typical) the cell dies. Germ cells and cancer cells seem immune to this notching and so are "immortal", so to speak, capable of living and dividing forever. In fact, immortality is one of the signs of malignancy in cells grown in the lab.

Cloning involves using the nucleus from a somatic cell and placing it in a germ cell. Unfortunately, the somatic cell may have too many notches on it and the animal that results may have limited numbers of cell divisions left. In other word, the cloned animal has retread tires in its nucleus. Dolly, the cloned sheep, died young.

Until this problem is worked out, cloned animals will not be viable alternatives to animals created from pure germ cells.

 

[archman]

I can very easily see science moving forward to the point whereby genetic diversity can be bioengineered. We would not necessarily be limited to replicating existing genetic types of a given species. Do you think my idea is out of the question? I admit this is flirting with the "playing God" side of the equation but is genetic engineering really that far away from this ability within lets say... the next 100 years or so?
Lance

Think of it this way. By the time cloning technology attains this point (your prediction of 100 years might actually be high), either everything will already be extinct, or there will be sufficient alternative applications (i.e. basic fisheries regulation) in place to do the job.

Heck, if governments simply enforced all of the environmental and fishery rules actually on their own books at present, you'd see a world (pardon the pun) of difference right there. That's the easiest and first place to start if you want to protect species... demand that governments put their money where their mouth is.

 

[archman]

Cloning has one additional problem: premature aging. There are two types of cells; somatic (body) cells and germ cell (sperm, egg). The chromosomes of somatic cells, but not germ cells (or cancer cells), have some modification after each cell division. In a sense, the cell carves a notch of its chromosomes after each division. After a certain number (I think 40 is typical) the cell dies. Germ cells and cancer cells seem immune to this notching and so are "immortal", so to speak, capable of living and dividing forever. In fact, immortality is one of the signs of malignancy in cells grown in the lab.

I've heard that the "incredibly shrinking telomere" process is still in dispute regarding premature aging in cloned critters, especially seeing as how Dolly and some other cloned critters had longer chromosome tips than they were supposed to.

Didn't Dolly die from a common lung infection or something? I know we had to stop teaching telomere degradation to our freshman biology students a few years ago because of some recent studies, or something. I really liked giving that lesson, too!ity_part

 

[J.R.]

... in the end, regardless the efforts we make in whatever form... nature will win.

Nature always wins...

J.R.

 

[drbill]

A population's genetic diversity at a specific point in time does give an indication of its ability to adapt to near-term change. Over generations there will be mutations that will affect genetic diversity and either reduce fitness or possibly offer more adaptiveness to environment change. Given the rate at which some environmental changes are taking place, it is possible (but perhaps not probable) that a cloned population with little genetic diversity could get wiped out.

My previous examples of genetic bottlenecks show that populations can indeed survive over time despite low initial genetic diversity.

Regarding our ability to genetically engineer diversity, I'm not so sure we can adequately or safely address that in a wild population.

 

[shakeybrainsurgeon]

I've heard that the "incredibly shrinking telomere" process is still in dispute regarding premature aging in cloned critters, especially seeing as how Dolly and some other cloned critters had longer chromosome tips than they were supposed to.

Didn't Dolly die from a common lung infection or something? I know we had to stop teaching telomere degradation to our freshman biology students a few years ago because of some recent studies, or something. I really liked giving that lesson, too!ity_part

Whatever the mechanism, I think the consensus is still that cloned animals are generally not as healthy as non-cloned animals? I may be wrong.

 

[shakeybrainsurgeon]

I've heard that the "incredibly shrinking telomere" process is still in dispute regarding premature aging in cloned critters, especially seeing as how Dolly and some other cloned critters had longer chromosome tips than they were supposed to.

Didn't Dolly die from a common lung infection or something? I know we had to stop teaching telomere degradation to our freshman biology students a few years ago because of some recent studies, or something. I really liked giving that lesson, too!ity_part

A quick check with an article from Nature Biotechnology: Dolly died at age six from virally-induced lung cancer (sheep normally die at age 12-16), although that illness has apparently been known to kill young sheep. She was abnormally overweight and had a case of advanced arthritis for her age, but post-mortem was otherwise normal. Her chromosome length was, on average 20% shorter than a typical sheep, not longer.

 

[bwerb]

I'm a little cynical when it comes to endangered species --- the vast majority of species that arose on this planet are extinct. All species have a limited tenure, and the thought of eliminating extinctions altogether is nonsense.

Agreed but we are the cause of this mass extinction in this case, not major climatic changes from meteor hits etc.

I believe the former, we are just another species. As such, we have a right --- in fact an obligation --- to promote our own welfare even to the detriment of other species because that's the way nature has worked for billions of years. If our presence makes hundreds of mammal or fish species extinct, then they deserve to go extinct, period. That's the way the game is played...and if our behavior makes the world inhospitable to us and we go extinct, then we deserve it too. Selfish behavior is the engine of evolution. Suppose the business world were run by environmentalists --- no company could be allowed to fold because we need "business diversity". Thus, the computer world would still be making Bowmar brains and commodore 64s because we would never allow them to go extinct from the market.

This is one of the most arrogant statements I have ever read on this board. "It's an obligation to promote our welfare to the detriment of other species"???

All species depend on all other species for survival...yes the "Lion King" had it right...it's all about the "circle of life". If you take a look at a real forest, not a replanted single species forest, but a real forest or a real coral reef etc you will see that nature is designed such that nothing is wasted. The waste and detrius of one animal/plant are food for the next...it goes around and around...huge diversity, huge degrees of interrelation between species.

Enter humans...we are the most massive creators of waste immaginable. Much of what we make not only simply builds up but is also completely toxic to both our environment and ourselves. Take a look at organochlorides...they are relatively unknown in nature and as such cannot be broken down by biological systems...we, created substances and chemicals which are not only completely outside of nature but are actually starting our own extinction.

I believe that there is a solution, and it involves business...and every other person on this planet and doesn't involve "environmentalists returning us to the stone age"

I'll suggest a couple great books which I think get it right.

http://www.amazon.com/Ecology-Commerce-Paul-Hawken/dp/0887307043

http://www.amazon.com/Natural-Capit...ef=pd_lpo_k2_dp_k2a_2_txt/002-1867624-7055264