Posted on 03/29/2006 1:47:22 PM PST by SampleMan
Spirals of DNA, once thought to be merely the passive memory banks that preserve life’s blueprints, may also actively modify themselves under certain conditions, according to Princeton University scientists.
A team of molecular biologists has found that some single strands of DNA are capable of removing a genetic building block from the spiral, a task previously thought to be impossible without the involvement of a separate catalyst such as RNA or proteins. Such removal, called depurination, occurs only at a single point within a particular genetic sequence, one that appears at least 50,000 times in the human genome. The team’s discovery that the removal occurs consistently in laboratory samples indicates that DNA is a more dynamic substance than was previously thought, and it raises the possibility that other unexpected behaviors still await discovery in this well-studied molecule.
“No one ever dreamed genomic DNA may have another function besides memory storage, but it apparently does,” said Jacques Fresco, the Damon B. Pfeiffer Professor in the Life Sciences at Princeton. “We don’t really know yet why or how it happens, but it makes us wonder what else DNA might be doing without our knowledge.”
Dr. Ann Skalka, senior vice president for basic science at the Fox Chase Cancer Center in Philadelphia, said the findings merit continued attention.
“This fascinating and unanticipated new property of DNA has the potential to cause substantial damage to our cells, leading to cancer or other diseases, unless it is controlled or exploited for some beneficial purpose,” she said. “We will stay tuned.”
Fresco’s team published its findings in the March 21 issue of the journal, Proceedings of the National Academy of Sciences. Also contributing to the research are Princeton researcher Olga A. Amosova and Richard Coulter, currently at West Chester University.
The double-stranded helical structure of DNA is a shape familiar to many, and these long, stringy molecules are in most circumstances unchanging and highly stable -- valuable characteristics for objects whose function is to preserve the master plan of the organism that carries them. Altering the sequence of a DNA strand is often necessary for innumerable bodily functions, such as growth and healing, but scientists previously thought that such alterations require other chemical catalysts or enzymes to do the clipping and rearranging.
When DNA does undergo such changes, its two strands sometimes separate from one another like a broken zipper splitting down the middle, the teeth of one side pulling away from the other. But in some cases, each side will then often bunch up so its teeth can latch on to others from the same side, forming small “loops” of a single-stranded DNA that extend out from the side of the double-stranded helix’s “stem.”
“For genes to express themselves and create change within the body, you absolutely have to get the two strands of DNA apart first, and it’s only through separation that DNA forms these stem-loops,” said Amosova, a research molecular biologist and Fresco’s long time collaborator. “Such separation occurs, for example, when genes are doing something to regulate the body.”
But the team found that if a stem-loop forms from a particular sequence of DNA, one of the genetic “teeth” will fall spontaneously from that side of the zipper, and the weakened strand will eventually break apart in that spot unless it is repaired by enzymes in the cell. Fresco said this sort of activity seems akin to self-mutilation at first glance.
“To a scientist, this kind of self-inflicted genetic damage appears unhealthy, the sort of thing that would cause undesirable mutations and could kill off the organism,” Fresco said. “Cells have evolved a complex DNA repair system to constantly repair such damage. But evolution has not, as we’d expect, put a stop to it. So we theorize it must be happening for some good reason that we have yet to uncover.”
Of the more than 3 billion DNA building blocks in the human genome, the 18-residue sequence that gives rise to the cleavage occurs in about 50,000 places -- a very significant number, Fresco said.
“We can only speculate now as to what aspects of biology this self-cleavage could influence, but the general function of stem-loops combined with the number of sites where depurination can occur does make us curious enough to look further,” Amosova said. “Such a self-depurination capability may, for example, be beneficial in sections of the genome involved in antibody production, where losing a building block from the sequence could lead to higher mutation rates in the antibody-coding genes. This, in turn, could lead to a larger variety of antibodies to protect the body more effectively.”
More generally, Amosova said, losing a building block increases the flexibility of the otherwise highly rigid DNA molecule, which in some circumstances needs to be bent.
“Flexibility could help with DNA packaging, which happens any time you need to stuff DNA into a tight place,” she said. “In particular, viruses typically pack a lot of DNA strands into their shells, leaving virtually no space unused. It may also play a role in the folding of DNA in chromosomes.”
Still, Fresco said, it remains too early to tell where the discovery will lead, though the team will look for some possible biological role for their finding.
“Thus far we have observed this effect under laboratory conditions that closely resemble those within the cell. Now, we would like to observe them directly in the cell nucleus,” he said. “If we have indeed found one way that DNA can change itself spontaneously, there might be others, and we plan to hunt for them.
“Additionally, I might mention that this discovery was made while we were exploring ways to repair the genetic mutation that causes sickle cell anemia,” Fresco said. “We noticed that the depurination occurs right next to the site of the mutation responsible for the disease, but we don’t yet know if there’s any relation between these two facts. We certainly hope we’ve noticed an effect that will eventually offer some new approaches to many diseases.”
Nice family pic. Is that your sister?
I gave verification, as did you. Thanks again.
I'm curious to know myself. My impression, from what I've seen from you here and in the past, is that you basically ascribe to "theistic evolution" (i.e., the idea that evolution took place much as described by science, yet under the guiding hand of God). I sure could be wrong about that, so let's have it!
I don't believe that this is actually an effect of electromagnetism; the spinning mass (supposedly) creates a gravi-magnetism force related to gravity in a manner analagous to the way magnetism is related to electricity. The superconductors are used because the electrons are totally free of electrical "friction" and the minute effect is clearly manifested, if I'm not mistaken (and I may very well be...).
I did, and it was rather interesting. I have two observations.
(1) The researcher says:
“To a scientist, this kind of self-inflicted genetic damage appears unhealthy, the sort of thing that would cause undesirable mutations and could kill off the organism,” Fresco said. “Cells have evolved a complex DNA repair system to constantly repair such damage. But evolution has not, as we’d expect, put a stop to it. So we theorize it must be happening for some good reason that we have yet to uncover.”
They're theory may be correct, and the inquiry is definitely merited, but it also may very well be that it is in fact unhealthy and undesirable, and that 'evolution hasn't put a stop to it' simply because it wasn't able to.
This brief quote actually points out two problems that I often see in biological research:
(a) the personification of evolution, as if it were, say, an intelligent designer.
Evolution doesn't 'plot things out'; it doesn't 'plan ahead'; and it doesn't 'put a stop' to things. Evolution doesn't do anything; evolution is what happens. There's an important conceptual distinction there.
(b) closely related, the “atomistic” approach to evolution (especially prevalent amongst sociobiologists), theorizing as if specific biological traits can evolve in and of themselves, without regard to structural constraints on design or to the possibility that given structural changes may not appear a possible outcome of the phylogenetic history.
In short, there are any number of plausible explanations why evolution may not have halted this phenomenon, even if it's damaging and of no benefit whatsoever. The researchers presumption that it must be beneficial or else "we'd expect" that evolution would've corrected it is an expression of cognitive bias. They might very well be correct when all's said and done, but there's no guarantee that they're correct, and evolutionary science certainly does not predict that they'll be correct (i.e., that if it's there, we'd 'expect' it to be beneficial).
(2) And my second broad observation is that: On the other hand, it may very well have a positive role in evolution. If so, then how can an added 'vector' of evolvement possibly be a problem for evolution? Quite to the contrary, if that were true - if in fact this does play a role in mutation and evolution - then it seems to me this would definitely be far more of a challenge to, say, ID advocates who reject the notion of beneficial spontaneous mutations.
So, anyway, those are my initial thoughts on all this.
Their theory, not "They're" theory..
That pretty much sums it up. I believe in God, and believe that he doesn't go around creating fossils in order to fool people. I don't think God's hand will be revealed, because we're intended to have free will and that would throw a wrench in things.
My lack of atheism makes me unqualified to speak according to many. I don't accept that principle. My ideas on evolution are not tied to my faith, as science is God's tool, no need for magic. I'm learning more about ID simply because I keep getting accused of lying about being an ID backer. Can't say I've researched the theory enough yet though, but I'm reading more on it out of a new found curiosity.
My major gripe with evolution backers (other than myself)is that too many of them are simply dogmatic attack dogs. For example, I don't think that current scientific understanding of mutation in evolution is correct. In fact, this article opens up a possibility. But I'm not allowed to voice that opinion without being called a closet ID proponent, a troll, and worse.
If evolution is taken out of schools (its taught in Catholic School by the way) it will be because these cranks ruined its reputation.
In short, I have no problem with religion in addition to science. I have a big problem with religion in place of science. And that is hardly because I want to drum religion out of schools and society (as I've been accused), but rather because I have a paramount self-interest in the progress of science and all the benefits it might bring, in particular to me! :)
My problem is with anything that I feel holds back progress.
As for the degree to which science "explains everything" you'll get no dispute from me. Science explains many things quite well, but we are hardly at the end of science so far as I'm concerned. Humanity has been doing science for a bare twinkling of atom by comparison to the grand sweep of the universe's history, and our scientific knowledge is growing exponentially, so who knows where we'll be in another thousand years, not to mention another 10,000 or 100,000 years.
I have no doubt there's plenty left to learn. Heck, most of what we have learned so far was achieved in merely the past few decades. An infinitesimal timespan in the grand scheme of things.
I concur with your statements concerning their overreach in stating that if it were bad, evolution would have eliminated it.
I've seen plenty of evolution apologists state eccentially the same thing, "It came about because it had a positive effect." or "It has a positive effect or it wouldn't exist."
This has always struck me as you would say, personifying evolution. A life form might mutate and evolve many negative traits, that simply aren't bad enough to make it go extinct (e.g. Helen Thomas). But evolutionary purists insist that evolution makes no mistakes. I simply disagree with the premise.
And yeah, I think these threads get way too heated way too often. I'm hardly innocent when it comes to that. I always regret it afterward, but c'est la vie!
It's tough to debate the meaning of life, the universe, and everything without getting a bit worked up sometimes..
Good night.
G'nite to you too!
That's, ugh... from the start.
"Maybe an Intelligent Designer???"
Why intelligent? I understand that some people might want to believe there is some kind of designer that existed before the existence itself(contradictory, but still..).
But, why "intelligent?"
There are a lot of imperfection, mutations, alterations, and randomness in the natural world to be called part of the "intelligent" creation. Unless the randomness and imperfections themselves are well thoughtout by a "designer."
Like modern art.
I'm sold by all this "evidence".
DNA "could" modify itself with no outside help, say biologists
"may" also actively modify themselves
"some" single strands of DNA are "capable" of
it raises the possibility
has the potential to
We can only speculate
"If" we have indeed found one way that DNA can change itself spontaneously,
Your ignorance of science and how it is applied as shown in your original post. If you truly knew how science worked you would never had made such a stupid remark.
What would be an example of "randomness"?
bump
Sorry, but I've been around too many college professors to accept that your Utopian world of science actually exists in the real world. The problem arises when you insert human beings into the process. They are jealous, self-agrandizing, and generally normal people, quite capable of ignoring science. The real beauty of science is that it eventually wins out over the scientists. If this observation makes you want to attempt ostracizing me by labeling me a troll, then so be it.
Are you attempting to make an argument? If so, I do not understand what point you are attempting to demonstrate.
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