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.”
no scientist has ever claimed such a thing period
You've stumbled on a bizarre auditory and reading comprehension syndrome peculiar to antievolutionists. When someone says, "we know some things about evolution," or "we know this or that particular thing," they for some reason hear, "WE KNOW ALL; BOW DOWN BEFORE US!"
I know many scientists in this big old world that are no where near as you describe and practice proper science.
I didn't call you a troll. What I am getting at is your complete ignorance of how science properly works or you know how science works but want to manipulate the situation for whatever your goal is. And by the way there is this thing called peer review and repeat experimentation that keeps scientists in line.
Enough said
What I am getting at is your complete ignorance of how science properly works or you know how science works but want to manipulate the situation for whatever your goal is.
Is there a post of mine that you are referring to? I'm aware of how science properly works, and also aware of how it often works, and that the imperfections have proved self correcting overtime.
You appear peeved that I pointed out that people who so admire the objectivity of science can get worked up into name calling. I once saw a tenured professor stand up and call a colleague an idiot. It got much worse after they progressed to family origin.
I don't follow the manipulation charge. Is this referring to my prediction of post quality, or because I posted the ID thread at all? I thought I might get some meaningful, well spoken counterpoints and a lot of abuse. I think I've gotten two of the former. And I thanked both of them for their input.
When people see boogie men behind every bush, there is usually a reason. I dare say you are allowing yourself a bit of paranoia.
You actually bring up a good point. All cutting edge research in science, no matter what field they are in, contains such suppositions. This is the type of research that tends to make the news. Usually, when a press release is made, there are some solid facts about the subject while some further verification is necessary for many of the finer points. If it was all solidly known, it wouldn't be very cutting edge, would it?
By the time something makes it to the level of a good textbook on the subject (which can take years or even decades), though, there has been much more peer review of the subject, and much more verification & testing. This is not to say textbooks never make mistakes (even the best ones occasionally do), but that by the time the process has worked to this level, one can be assured that the central tenets of what one is reading are correct (in a reputable text, anyway).
Science always attempts to improve itself through time; theories that are broad in scope are almost never completely discarded (they don't need to be) - they are refined and brought into better focus. The basic core tenets of evolution, gradual change through time, have not changed since the time of Darwin. What we see now, though is positive identification and evidence that refine the detail of his theory in ways Darwin could never have dreamed.
It also is an (un?)fortunate fact, though, that science has become so complex that the finer details of the supporting evidence for theories take many, many hours of dedication and time to understand -- to those without the time and/or desire to do their homework on the subject, the results that science presents can indeed look like a potpourri of nonsense and proposition of faith, even though they aren't.
This is not to say textbooks never make mistakes (even the best ones occasionally do),
I know ONE textbook that has no mistakes in it.
What do you mean? The main phenomena being reported is asserted completely definitively. They say exactly what the phenomena is, when and where it occurs (in the lab, unobserved as yet in the cell but expected to occur there also) and the exact DNA sequence associated with the phenomena (not given in this popular article of course, but in the research paper).
They seem to state definitively everything that so warrants. What, specifically, do you think should have been stated definitively that wasn't? Or is your complaint entirely cynical and hypocritical (i.e. you would have made the accusation of dogmatic assertiveness with equal felicity if they did say more definitively)?
Evo articles are ALWAYS
full of if, could have, might have, may have,
might possibly be, etc etc etc.
Actually evolution is only mentioned one time in the article, in connection with the inference that this phenomena must not be deleterious, and is likely functional in some as yet unknown way, because otherwise evolution would have eliminated it.
So the one mention of evolution IS definite: evolution eliminates purely deleterious traits, so this one must be otherwise. Ironically it's all the questions about the design related functions of this phenomena (what precisely it does functionally, are there other phenomena of the same type, etc) that are -- however properly due to the need for further research -- couched in maybe's and possibly's.
One of the main reason I stay with
"Thus says The LORD"
No you don't. The LORD sayeth nothing whatever about computers and computer networks, for instance, but here you are.
Can they rule out DNA being hit (altered) by sub-atomic particles?
No you don't. The LORD sayeth nothing whatever about computers and computer networks, for instance, but here you are.
Weak very weak
" What do you mean? The main phenomena being reported is asserted completely definitively."
The title and the first paragraph say you are wrong.
"DNA ""could"" modify itself with no outside help, say biologists"
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.
Are "could and may" definitive words .
Listening to the crickets chirp while waiting for a citation for:
1) A post where I told someone to shut up
2) Any scientists who has ever said that everything there is to know about evolution is already known.
How am I wrong? Your quotes confirm exactly what I said: that the statements about design features of the DNA wrt this phenomena -- its role if any in the DNA, whether it is representative of similar phenomena, etc -- are couched (appropriately) in hypotheticals and uncertainties. By contrast the one statement regarding evolution -- that it would eliminate such a phenomena unless it provided some benefit -- is definitive.
Really?
You're wrong.
Read the three accounts of Peter's denial of Christ, then tell me which version got the genders and identities of the denial correct.
Also, much of the Bible is intended as allegory. You don't really hate your children do you? This is what Jesus literally demands in Luke 14:26.
There are errors of detail in the Bible, and what's more, the Bible is not a science text. It has no authority in that realm any more than it has authority as a phone book. Most of the science portrayed literally in the Bible is blatantly wrong.
Most of the science portrayed literally in the Bible is blatantly wrong.
Prove it
No thank you. That work has already been done; not my job to reinvent the wheel. Crack open a few intro-level science books and you can see the work that's been done over the last millenium or two for yourself.
You don't believe in all of the Bible literally. I don't know why you're so insistent on taking the first two chapters as verbatim fact.
Crack open a few intro-level science books
I will if you will crack open the Bible
and ask God to reveal the TRUTH to you.
Deal?
You don't believe in all of the Bible literally.
And you know this how?
Fine. I've already read it cover to cover and contemplated it all, but one could spend a lifetime doing so and not understand all its mysteries - maybe it's time for me to get back to reading it more often.
Truth by revelation is fine in spiritual matters, but please understand that science wouldn't get very far if it worked that way. When I have a spiritual or moral question, I'll look in a Bible. When I have a science question, I'll consult good science books.
I perused your homepage, by the way. Looks like you are blessed with a wonderful family - best of luck & blessings to you and them.
All you have to do is read the FR religion forum to realize that no sane person could claim to take everything in the Bible literally. No two people read things the same way, and the differences of interpretation are not trivial.
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