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.”
"...everything there is to know about evolution is already known Kool-Aid" placemarker.
I do not understand. Could you elaborate?
It's not surprising that you don't understand.
The Bible says as much.
1 Cor. 2:14 The man without the Spirit does not accept the things that come from the Spirit of God, for they are foolishness to him, and he CANNOT understand them, because they are spiritually discerned
(NOT Scientifically figured out,my words)
John 3:3 In reply Jesus declared, I tell you the truth, no one can see the kingdom of God unless he is born again.
John 14:6 Jesus answered, I am the way and the truth and the life. No one comes to the Father except through me.
Acts 4:12 Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved.
Rom. 10:13 for,Everyone who calls on the name of the Lord will be saved.
Try it you will not regret it through out eternity.
That is impossible, as my conscious mind will not exist through out eternity
To believe that all there is to life is what we have on this earth has to be the saddest and most depressing existence that I can think of. To think that we are born, live a few years, accumulate a few things and then die just doesn't afford much hope does it?
The Bible is very clear that we will have eternal life. It's just a matter of where one chooses to spend it.
John 3:16 For God so loved the world that he gave his one and only Son,that whoever believes in him shall not perish but have eternal life.
John 3:36 Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God's wrath remains on him.
John 5:24 I tell you the truth, whoever hears my word and believes him who sent me has eternal life and will not be condemned; he has crossed over from death to life.
John 6:40 For my Father's will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise him up at the last day.
Which could be a good argument that the Bible isn't incompatible with science as some feel it is. And that believing in the Bible isn't as likely to lead us back into superstition and the Dark Ages as some would also have us believe. Christians are not the anti-science Luddites as often portrayed. The primary area of disagreement here is on origins and the interpretation of the fossil record.
The Bible also addresses several topics which have been confirmed by science, which the ancients would have had no way of knowing about. Some of them are the water cycle, that winds form a circulating system, the life is in the blood, there are oceans currents in the sea, to name a few. It gives credibility to the concept that the Bible IS divinely inspired when things are mentioned that they people of that age would have no way of knowing by themselves.
Surely it doesn't require revelation to notice that animals can bleed to death.
I have no doubt at all that the Phoenicians, Greeks, and other seafareres knew about currents.
What about the rest?
How would they know about the circulating system of the atmosphere? Eccles 1:6,
Or the water cycle? Job36:27,28 and Eccles 1:8.
Or that everything was being held together or that everything even NEEDED to be held together? Col 1:17 Where would they have gotten that concept? Nothing in our experience would indicate that stuff needed to be held together but here we have discovered gravity and strong and weak molecular forces.
There are people opposed to science all over the religious spectrum - many Christian, many atheist, many everywhere in between. No argument from me there. On my (short) homepage I point out that spirituality and science are both of importance to the future of our nation and all of humanity, and I seriously mean it.
The primary area of disagreement here is on origins and the interpretation of the fossil record.
It goes much further than that, though. I've always believed that the fossil evidence is given disproportionate attention here, for one. It makes a strong case for evolution, but certainly not the only one. I might not be totally convinced myself if this was the only line of supporting evidence. The genetic evidence is much stronger (but harder to understand to most people, myself included). Biogeography (i.e. where related types of life are found) is also of paramount importance. Add shared morphologies, vestigial organs, observed cases of speciation, ring species, etc. - one can explain away any one or two of these, but all these different and varied supporting points? If evolution didn't occur, it sure seems the Creator went through some great pains to make it appear so. The mere "coincidence" that all these lines of inquiry yield the same picture is what lends so much confidence to the theory - not just one of 'many possible interpretations' of the fossil record.
The Bible also addresses several topics which have been confirmed by science, which the ancients would have had no way of knowing about.
I don't know that that's true, but it's irrelevant as to its authority in spiritual matters, anyway. I don't think accurate science is the point or reason for the Bible. The Bible's credibility comes from the practice of applying its principles and messages in our personal lives and the spiritual strength it gives.
I don't disagree with that either but if someone is not spiritually inclined, the argument is moot because it is not considered valid.
There have been some posters here who have stated that the conflict they see between science and Christianity has caused them to abandon faith/the Bible/Christianity/ whatever they wish to call it in favor of science. There are also others who don't acknowledge the existance of the spiritual realm and so for them, that line of reasoning doesn't work either.
I see the commonality in design because the creatures all live in the same environment and many subsist on the same foods or each other. It would seem that there would need to be similarities so nourishment could be provided.
If all the species were really different, I could see that as an argument against ID also. IOW, why would the designer have designed species so incompatible? Either way, it seems that the ID theory would be discredited.
I don't really think bleeding to death is a common enough form of demise for people to make the connection. Sometimes creatures die without bleeding. Sometimes some bleed lots and live while others bleed little and die.
Many cultures also believe that people or animals die because their spirits are eaten so even if some animal or person is observed bleeding to death, it's still not recognised as the cause because, after all, everybody knows the real reason. (The People Time Forgot by Alice Gibbons)
placemarker
ping
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