Forgot your password?
typodupeerror
Wireless Networking Medicine Science

How Terahertz Waves Tear Apart DNA 279

Posted by kdawson
from the tear-a-cell dept.
KentuckyFC writes "Great things are expected of terahertz waves, the radiation in the electromagnetic spectrum between microwaves and the infrared. Terahertz waves pass through non-conducting materials such as clothes, paper, wood and brick and so cameras sensitive to them can peer inside envelopes, into living rooms and 'frisk' people at distance. That's not to mention the great potential they have in medical imaging. Because terahertz photons are not energetic enough to break chemical bonds or ionize electrons, it's easy to dismiss fears over their health effects. And yet the evidence is mixed: some studies have reported significant genetic damage while others, although similar, have reported none. Now a team led by Los Alamos National Labs thinks it knows why. They say that although the forces that terahertz waves exert on double-stranded DNA are tiny, in certain circumstances resonant effects can unzip the DNA strands, tearing them apart. This creates bubbles in the strands that can significantly interfere with processes such as gene expression and DNA replication. With terahertz scanners already appearing in airports and hospitals, the question that now urgently needs answering is what level of exposure is safe."
This discussion has been archived. No new comments can be posted.

How Terahertz Waves Tear Apart DNA

Comments Filter:
  • by Anonymous Coward on Friday October 30, 2009 @08:59AM (#29922621)
    Who cares if we turn into an entire country of genetically deformed freaks, at least we'll be a country of SAFE and FREE genetically deformed freaks, right? Just as envisioned by our Founding Fathers. God Bless America.
    • Remember citizen (Score:4, Insightful)

      by Nursie (632944) on Friday October 30, 2009 @09:03AM (#29922649)

      continuity of the state and its power structures is far more important than petty things like individual freedoms or human lives.

      • Re: (Score:3, Informative)

        by cerberusss (660701)

        continuity of the state and its power structures is far more important than petty things like individual freedoms or human lives.

        Yep, and things like the Universal Declaration of Human Rights [wikipedia.org] are only for people like us, not sub-human towelheads, Jews, Christians, Arabs, Catholics, Scots, Buddhists, dissidents or other noisemakers.

        • Re: (Score:3, Insightful)

          by dintech (998802)

          I'd rather unzip my trousers than than let this 'frisker' unzip my DNA. Who knows, a naked security line might actually make airports fun again.

          • Fun or many people screaming "My eyes! My eyes! I have been blinded!"

            Personally if this make that scanner wall from total recall a reality I would be for it. But only if they can prove that we are not harming out DNA in the process.

    • Re:Who cares... (Score:4, Interesting)

      by Xest (935314) on Friday October 30, 2009 @09:54AM (#29923125)

      Yeah exactly, so what if I have to have my arm amputated because of an agressive cancer caused by these scanners, at least it means I wont have to lose my arm to a terrorist!

      • Already, a friend of mine that's a cell phone addict (and has been since they were 'perfected') has had numerous benign growths removed from her face.

        EMI apparently has, at various freqs, the ability to rattle our anatomy. To what extent-- we need to know, and know soon.

        When I go through the airport scanners and get stripped by UUHF waves, I wonder just what's getting blown around inside me. Maybe low and vhf weren't as nasty. Maybe they were. The problem is: we don't know and we oughta find out in finality

        • by Xest (935314)

          Tell me about it, it's nasty stuff. I carry my cell phone in my pocket all day every day and sometimes I get this growth between my legs.

  • by eldavojohn (898314) * <eldavojohn@gmFREEBSDail.com minus bsd> on Friday October 30, 2009 @09:02AM (#29922645) Journal
    Reminds me of the time I was at the Science Museum in Minnesota and they had an exhibit from the Museum of Bad Science (or something like that). Anyway they had a shoe-fitting flouroscope [hemonctoday.com] which was a device that shoe stores bought. Basically you would put shoes on your child's feet but to see how well they fit you would jam their leg in this thing and see the bones of the toes up to the tip of the shoe and see how well it fit. See the problem yet?

    Although store clerks were frequently exposed to the radiation from the machines, the radiation was more dangerous to children who placed their feet directly into the radiation. The exposure rate is thought to have been approximately 0.005 Gy to 0.058 Gy per second. If children tried on several pairs of shoes per visit it was posited that they could be exposed to as much as 0.1 Gy to 1.16 Gy. In fact, experiments indicated that radiation could exceed 1 microGy per hour as far as 10 feet away from the machine.

    This device should be a warning (and I think it has been if you look at how cautious people are of new technologies like cell phones). Hopefully my sperm aren't being fried when I walk through a scanner in an airport--at least the parents of the 30s were using X-rays for their convenience and not the invasion of their privacy!

    • by Sockatume (732728)

      It wasn't any better than just measuring the kid's feet, to boot. Shoe-curity theatre.

    • by nitehawk214 (222219) on Friday October 30, 2009 @10:49AM (#29923791)

      This is exactly what I thought of when I read the summary. In fact I just saw the episode of Modern Marvels: Engineering Disasters that covers this topic last night.

      My favorite: the Revigator [periodictable.com]!

    • Re: (Score:3, Insightful)

      by gad_zuki! (70830)

      >Hopefully my sperm aren't being fried when I walk through a scanner in an airport--at least the parents of the 30s were using X-rays for their convenience and not the invasion of their privacy!

      Airports use metal detectors for humans, not xrays. The new millimeter wave machines arent xrays. As far as safety, have is been demonstrated that these machines damage organisms in regular usage? It seems to me that a lot of this is reactionary nonsense like "I'm allergic to wifi!!" nonsense.I am concered about

      • Re: (Score:3, Funny)

        by Sockatume (732728)

        have is been demonstrated that these machines damage organisms in regular usage

        Actually, that's what the article opens with: there are conflicting experimental reports (none involving extra heads or hair falling out, mind you) it seeks to clarify. Worth reading IMO.

      • Re: (Score:3, Insightful)

        by codegen (103601)

        I know this is slashdot, but did you read anything before replying? The article in discussion (at the top of the page fyi) discusses the discovery that millimeter wave radio waves appear to be resonant with DNA, resulting in significant DNA damage. Yes the new millimeter wave machines are not Xrays. But this is new research that shows that the effects may be greater than anticipated. It certainly bears looking into to determine if there is a problem.

        The parent poster was drawing a similarity in the use to

    • Reminds me of the time I was at the Science Museum in Minnesota and they had an exhibit from the Museum of Bad Science (or something like that).

      It is the Museum of Questionable Medical Devices [museumofquackery.com]. (It used to be housed in St. Anthony Main, but when that clsoed they moved it to the Science Museum.)

    • Re: (Score:3, Informative)

      by painandgreed (692585)

      The exposure rate is thought to have been approximately 0.005 Gy to 0.058 Gy per second. If children tried on several pairs of shoes per visit it was posited that they could be exposed to as much as 0.1 Gy to 1.16 Gy. In fact, experiments indicated that radiation could exceed 1 microGy per hour as far as 10 feet away from the machine.

      To put this into context, the Gy (gray), is the amount of absorbed radiation. One gray is typically the point where physical effects are felt, usually in a burn to the skin

  • by h4rm0ny (722443) on Friday October 30, 2009 @09:04AM (#29922655) Journal

    So if there's a hysterical OMGCancer panic amongst the scientific illiterate, is it ethical to take advantage of that to protect ourselves against the privacy abuses of these things at train stations and airports and on the street?
    • by oldspewey (1303305) on Friday October 30, 2009 @09:06AM (#29922685)

      Hasn't it always been the case that you have the option to decline to use "the machine" and be hand-searched instead?

      Until this issue gets resolved, that's what I plan to do anyhow.

      • by Idiomatick (976696) on Friday October 30, 2009 @09:10AM (#29922717)
        If they had two lanes that'd be fine and dandy. But refusing to be searched and requesting to be done by hand is making yourself a suspect. As soon as you ask that enjoy being treated like you tried to sneak a gun on board.
        • Re: (Score:3, Informative)

          by blueg3 (192743)

          I'm not sure which airports you go to, but the ones I go to, about half the people searched opt not to use the scanner, and the TSA agents clearly don't give a damn which route you take.

      • by AioKits (1235070) on Friday October 30, 2009 @09:22AM (#29922835)
        With my assorted body jewelry I find it less hassle to actually be patted down. The scanners (last time I flew it was a millimeter waves scanner) always detect something 'on me'. The last time I went through they pulled me aside and asked, "Do you have anything on your chest sir?" I thought they were asking if I had something I wanted to tell them so I said no. They had to clarify, "Do you have any foreign objects on your chest?" I have one ring in that area, but it is only 12 gauge and not big enough to be mistken for anything really. So... I was escorted to a lil clear box, patted down, and sent on my way.

        I have little to no shame, so it didn't really bother me he was patting me down. In fact he seemed to grimace at the fact he had to do it, which made it all the more enjoyable to me.

        So now I just skip any of the scanners and opt for a pat down. It slows down security, it appears to make them uncomfortable, and if I'm lucky it'll be someone attractive patting me down.
    • Re: (Score:3, Insightful)

      by Yvanhoe (564877)
      What is this ethics thing you are talking about and since when was it relevant to fight in a political arena ?
      • Re: (Score:3, Interesting)

        by Chris Burke (6130)

        What is this ethics thing you are talking about and since when was it relevant to fight in a political arena ?

        I'll field this one.

        "Ethics" is the name of one of a number of flags that politicians can drape over their shoulders, automatically causing their arguments to be perceived to represent the trait represented by the flag, and just as importantly their opponent's arguments as being against that trait. Only the first side of an argument to don a given flag receives the benefit, as opposing sides attemp

  • by Anonymous Coward on Friday October 30, 2009 @09:04AM (#29922659)

    If you follow the link provided about the airport scanners you find that they are passive devices meaning they don't emit terahertz waves they only recieve the waves coming off of everything around us.
    There are some devices out there that using terahertz radiation to inspect packages much like x-ray today.

    • by Gadgetfreak (97865) on Friday October 30, 2009 @09:10AM (#29922723)

      For now. But the last paragraph of the MIT article indicates newer cameras will have their own emitters.

      • by natehoy (1608657) on Friday October 30, 2009 @09:57AM (#29923161) Journal

        The MIT article has no citations to any models coming out that use active scanning. Meanwhile, the article summary clearly implies, no, actually STATES, that they are being introduced already into airports. Which is patently false. Active scanners ARE being introduced, but they are milliwave body scanners, and these passive t-wave scanners appear to be a more effective and safer alternative.

        "With terahertz scanners already appearing in airports and hospitals, the question that now urgently needs answering is what level of exposure is safe."

        The "terahertz scanners already appearing in airports", like the cited ThruVision T5000, are passive units. There is no discussion about "what level of exposure is safe" because there is no exposure to terahertz radiation. It's detecting what your body and possessions are already emitting.

        The t-band scanners are being tested for two reasons that seem to make sense to me, at least:

        1. Their imagery can detect materials more accurately whilst simultaneously not getting as accurate a picture of the actual body. This is better scanning with better privacy.
        2. The new scanners are passive t-ray detectors as opposed to active milliwave detector.

        Better scanning, less violation of privacy, no active emitter. If true, this sounds like a trifecta to me. I'd much rather pass through one of these than a milliwave unit.

        If and when ACTIVE t-band scanners start being introduced into general airport use, I'll share your concern and be right there with you in the pat-down line.

        • Re: (Score:3, Interesting)

          by TheCarp (96830) *

          > Better scanning, less violation of privacy, no active emitter. If true, this sounds like a
          > trifecta to me. I'd much rather pass through one of these than a milliwave unit.

          I would rather pass though none at all. It all looks like one big barrel of privacy invading pork to me. A costly solution to an imaginary problem. That leaves us all with less privacy, to absolutely no benefit to anyone except the people with cushy TSA jobs.

          -Steve

        • by Anonymous Coward on Friday October 30, 2009 @11:20AM (#29924249)
          Disclaimer: I am an expert in millimeter-wave and terahertz imaging systems.

          I wanted to emphasize to everyone reading this is that the parent is exactly right. ThruVision (the only commercial terahertz imaging system currently in airports) is passive, in that it detects the blackbody radiation being emitted by your body, clothes, and other objects, and compares it to the blackbody radiation of the background. The apparent difference in radiometric temperature is what constitutes the final image. There is no emission of terahertz radiation by this system.

          On the other hand, the active microwave systems, which operate around 35 GHz (there are variations on this, of course) are essentially an active radar system. You are exposed to some non-ionizing radiation, and its reflection from your body, clothes, and other objects is received and compiled to create an image. In terms of radiation, then, the active microwave systems are irradiating you, but at a level far below your cell phone. I can give citations if you like (or refer to the SPIE conference publications by the Pacific Northwest National Lab group who pioneered the system that is currently in airports.)

          Or we can talk about privacy. The active microwave systems have far better spatial resolution than the passive terahertz systems, since they take full advantage of phase in the imaging, and have a great SNR due to transmitting their own microwave power. (the passive systems mostly use direct detectors, which are really only sensitive to the magnitude of the radiation. ThruVision's, though, uses a heterodyne receiver, and thus is quite sensitive, but since it is very narrow-band [340 GHz, +/- 5 GHz], its sensitivity is similar to a direct detector) Fancy radar algorithms give you spatial resolution far better than the diffraction-limited optics definition you are probably used to hearing about. On the other hand, the passive terahertz systems are limited by the diffraction limit, and thus their operational wavelength gives you a good idea of their spatial resolution.

          You would then say that a passive terahertz system operating at 1 THz would give you much better images than a passive system at 340 GHz, and in terms of spatial resolution you are right. However, it is commonly known that clothing transmittance drops off quickly as frequency increases from 100 to 1000 GHz (and of course even more at higher frequencies, which is why you don't see thermal IR cameras being used to detect ceramic knives under your clothes). So, somewhere between 100 and 1000 GHz is a happy medium in terms of spatial resolution AND being able to see through multiple layers of clothing.

          And yes the parent was also right that the passive terahertz systems are very bad at gathering an image of the body, since it is essentially isothermal. No radiometric temperature contrast? No image.

          One thing that everyone has missed is the amount of power needed to "unzip" DNA with terahertz frequencies. (TFS poses this question, actually. The answer is in the arxiv article.) It's actually quite high, and it is very difficult to find a source that can emit this level of power. Yes, there are terahertz lasers (at the several microwatt level), but you should be more afraid of a 10 micron CO2 laser that will punch a hole through your chest, and is also quite invisible.
    • by Shrike82 (1471633) on Friday October 30, 2009 @09:12AM (#29922745)

      If you follow the link provided about the airport scanners you find that they are passive devices meaning they don't emit terahertz waves they only recieve the waves coming off of everything around us. There are some devices out there that using terahertz radiation to inspect packages much like x-ray today.

      Thankyou. The summary implies that scanning using T-waves in airports might cause you to have your DNA scrambled, which is just plain wrong. Passive scanning (which we are told is what the airport scanners are) don't expose you to any more radiation than you get in a normal day.

      • Re: (Score:3, Informative)

        by Anonymous Coward
        I replied to the parent as AC also, just so you get an idea of who this is.

        I wanted to clarify again: the microwave systems are NOT passive. If it looks like this [dsxray.com], it is an active microwave system, basically a radar. (I have to question their sanity in that the URL contains "xray"... real smart guys, real smart.) These systems produce images like this [canada.com].

        Passive narrowband terahertz systems produce images like this [akademon.cz]. (this is actually one of ThruVision's... it's in an SPIE conference paper from a few y
  • that besides my geiger muller counter, my gas spectroscopy meter, and my decibel meter, I have to carry a terahertz microwave detector with me all the time?

  • Incident at LAX (Score:2, Interesting)

    by BadAnalogyGuy (945258)

    I was at LAX with my family several months ago and there was a huge line to go through the metal detectors. Tempers were up, to say the least.

    Ahead of me there was a group of Arabs, kaffiyeh, long beard, the works. Behind them was a little white haired lady apparently on her way back to "Mizzurah" after seeing her grandkids in LA. Sweet as can be old lady, the kind that talks to much to strangers on the airplane. Single serving friend, you know.

    Guess who gets stopped by the TSA.

    Needless to say, everyone in

    • I have to say that the only time I was set aside to be in the special search category, everybody else in the group was from the middle-East or India. It was quite clearly obvious that they were profiling based on ethnic origin.

      (*In my case, the "profile" was that I'd bought a one-way ticket only one hour before the flight. Apparently the profile of terrorists is that they buy tickets at the last moment. True? Probably not.)

    • Re: (Score:2, Interesting)

      by swarsron (612788)

      so you suggest we profile people by their religion *and* create an easy to circumvent security protocol? Genius

      • My business of smuggling illicit recreational chemicals has become so much easier after 9/11. All my people dress with long beards and try to look arab(takes some training). Alright so it's not fun when the man with the glove comes but they never get checked for drugs. I lost a few that were sent to Uzbekistan but hey, it's not supposed to be a safe business.

    • Re:Incident at LAX (Score:4, Insightful)

      by gad_zuki! (70830) on Friday October 30, 2009 @10:57AM (#29923919)

      >Needless to say, everyone in line was a bit pissed that the TSA was giving extra screening to the old lady when they just waved the Arab guys through without a second glance.

      Err, racial and religious profiling has serious drawbacks. Random testing along with metal detectors, milimeter scan, etc is a better way. Not to mention terrorists arent stupid. Theyre not going to dress up in full garb. The 9/11 hijackers wore street clothes and business casual clothes.

      Terrorists and drug smugglers also prey upon the weak and stupid. I can remember how many times Ive been asked to "hold my bag please, it is a package for my son" in line to get on a plane or a train.

      >"What the fuck are you morons searching her for? The towelheads are the ones flying shit into buildings!"

      Stay classy.

      >Maybe scanned him a few extra times to make sure his DNA was totally fucked up.

      With what exactly? The passive metal detector and passive millimeter wave device? Perhaps it would behoove us all in air travel if didnt point at funny looking people and scream "terrorist" like the moron in your story.

  • by MadCow42 (243108) on Friday October 30, 2009 @09:07AM (#29922697) Homepage

    The times I've encountered the terahertz scanners at airports, they've always been optional (although they don't make it clear to you that it is). If directed to one, I've always simply asked if I must use it or if I had a choice of a "normal" metal detector. EVERY time they've allowed me to choose (and I travel a LOT). Most times they take a note of it or ask me to sign a sheet to indicate my declination - I assume so they can figure out if people object or not.

    Asking the quesiton never hurts. It also sends the message that this intrusion isn't accepted by the public. Don't surrender to these things willingly.

    • All the scanning and waiting in line for it and having luggage checked and so on is such a big time sink. I don't think I'd ask for another detector, because I'm just happy if I'm finally there instead of waiting in line and just want the whole process to be over as fast as possible.
      • by MadCow42 (243108) on Friday October 30, 2009 @10:02AM (#29923207) Homepage

        Actually, when I decline, they've always walked me to the front of the line for the other detectors. It's saved me time in the end, strangely enough.

        A few other times, when it was my turn, I simply walked to the standard detector myself, and had no issues.

        (they have two normal lanes and one terahertz scanner lane at my departure airport, but I've run into them in many other places recently too)

  • Translation (Score:3, Informative)

    by commodore64_love (1445365) on Friday October 30, 2009 @09:10AM (#29922713) Journal

    "This creates bubbles in the strands that can significantly interfere with processes such as gene expression and DNA replication." i.e. The birth of cancer cells. Terahertz waves are carcinogens.

    • Re: (Score:3, Informative)

      by Sockatume (732728)

      That would depend on the degree. Your DNA's a mess at the best of times from exposure to the normal background of crap, and would be a mess in isolation by its very nature. The body has coping mechanisms: the question is, is this significant enough to pose them problems? The answer, according to this paper's lit review, is "sometimes, at a high enough or sufficiently prolonged level of exposure or at a particular frequency".

    • Re: (Score:3, Interesting)

      But what if Terahertz waves can also be used to kill a cancerous tumor? Think about this ... take to sources of focused EM energy beams, neither in the Terahertz range, and aim both energy beams at a cancerous tumor. When the two energy beams coincide at the tumor, through constructive interference, localized Terahertz waves are generated that disrupt the DNA of the cancer cells to the extent that those cells can no longer replicate. Since the energy is localized, damage to the surrounding body tissue is mi
      • (T)ake to sources of focused EM energy beams, neither in the Terahertz range, and aim both energy beams at a cancerous tumor. When the two energy beams coincide at the tumor, through constructive interference, localized Terahertz waves are generated that disrupt the DNA of the cancer cells

        That is not how interference works - interference modifies the intensity of the beam, that is the number of photons which would be observed at any given point. It does nothing to the energy of the photons - interfering light only gives light, interfering microwaves only gives microwaves, and so forth.

  • by elrous0 (869638) * on Friday October 30, 2009 @09:11AM (#29922741)
    You would deprive us of hundreds, if not thousands, of leaked nude photos of famous celebs just to save a little DNA?!?!? Are you insane, man????
  • Now where do I go to buy a camera that can virtually unzip people so that I can go do some research on it's side effects?

  • Doesn't worry me (Score:4, Interesting)

    by Dolphinzilla (199489) on Friday October 30, 2009 @09:26AM (#29922875) Journal

    If you read the story this conjecture is the results of a computer model ...NOT real measurements of actual damage to DNA - since no previous actual experiments have turned up any damage then I'd say the model is not quite right - at any rate its all theoretical and not proven with experiment

    • by _LORAX_ (4790) on Friday October 30, 2009 @09:38AM (#29922963) Homepage

      This is good science. It gives experimental research a direction to look in. If they find the same result it will validate this computer model, if they still can not the computer model needs to be thrown out or reworked. There will always be differences between theory and experiment, this is probably just one of those cases.

      It may not matter though, with the number of people that can not differentiate between theory and reality this may stop terahertz scanning dead since people are dumb and panicky when it comes to crap like this. People still think WiFi or cell phones can give you cancer. Better yet, most people can't even tell you the difference between a tumor and cancer and use the terms interchangeably.

      • I agree - we often use models at work to predict what will occur when we build systems - we also try to refine our models with experimental results - I think relative to Terahertz radiation effect on human cells and DNA there is still much work to do, and as you point out there are many who still buy into the cell phone cancer myth. I really hate when a true story of science gets sensationalized and turned into FUD....

    • by Sockatume (732728) on Friday October 30, 2009 @09:51AM (#29923093)

      Actually, it's a theoretical explanation for some difficult experimental results. The issue was that some studies suggested that THz radiation would be harmful at any frequency/power range, while others pegged it as only being significant at particular resonant amplitudes or frequencies. It transpires that in the presence of thermal perturbations, you do indeed get some non-specific disruption of the base pairing, which would only be an issue if you had a long enough exposure to actually get a significant thermal perturbation and thus cause a very significant disruption. However there is also a resonant mechanism, at a particular frequency with a critical minimum amplitude, that can immediately cause a significant disruption, without the need to wait for a particularly big thermal perturbation. That's my reading, anyway.

      • Re:Doesn't worry me (Score:4, Interesting)

        by radtea (464814) on Friday October 30, 2009 @10:27AM (#29923495)

        Actually, it's a theoretical explanation for some difficult experimental results.

        Which itself needs to be experimentally verified. The model they are using is fairly simple. In particular, they introduce the terahertz driving force into the model by hand. That's ok to suggest that under reasonable assumptions it is plausible that terahertz radiation can drive non-linear breathing-mode resonances that can create localized "bubbles" in double-stranded DNA, where the linking bonds between the two strands are broken. But it's a long, long way from a solid empirical result.

        Of course, if you believe GCM's are a sound basis for public policy, you would have to argue that there is no need to do any experimental follow-up on this: simply use the computer model to determine the safe limits. There should be no problem with that because this model is orders of magnitude more realistic than the best GCM.

        • Re: (Score:3, Interesting)

          by Sockatume (732728)

          Sure, sure, I won't believe it until I see some DFT and experimental results from some actual physical chemists, I'm just pointing out that this isn't a pie-in-the-sky hypothesis. And absolutely, research this early shouldn't drive policy.

  • by damn_registrars (1103043) <damn.registrars@gmail.com> on Friday October 30, 2009 @09:34AM (#29922927) Homepage Journal
    The summary mentions that the terahertz waves "tear apart" strands of DNA. For those who might not remember their undergraduate biology, DNA strands are held together by hydrogen bonds - not covalent bonds. So the total amount of force to "tear apart" two strands is not as great as you might imagine. For that matter, strands have to be "torn apart" in order to be replicated for cell division.
    • by Sockatume (732728) on Friday October 30, 2009 @10:03AM (#29923215)

      The authors aren't concerned about it unzipping the entire DNA strand like string cheese. The process creates local regions of unzipping, which your DNA gains and loses as a matter of course. These unexpectedly-open regions interfere with replication and translation, but your DNA can cope with the the "normal amount", so the question is whether these additional regions are enough to be a problem.

  • Double Stranded? (Score:3, Insightful)

    by AP31R0N (723649) on Friday October 30, 2009 @09:49AM (#29923075)

    i thought all DNA was double stranded. Is there single or triple stranded DNA? If all DNA is double stranded, why mention strandedness at all?

    i'm not trolling, i'm asking a question. Yesterday some jerks with more mod points than sense labeled me as a troll for asking questions.

    • by Sockatume (732728) on Friday October 30, 2009 @10:10AM (#29923305)

      Single-stranded DNA has its information-encoding side exposed and flops around kind of pathetically. Double-stranded DNA sticks the two information-encoding sides together so that they're hidden and inactive, and helps you wind up and store the DNA. However the double strand can "unzip" along a small part of its length to expose two single strands which can go to work.

      You can get triple-stranded DNA, but it's not traditionally been thought of as important. Normally the groove for the third strand would be occupied by proteins involved in the function and maintainence of the DNA instead. However it now seems that forming a triple strand in some regions might be important in DNA's control mechanisms too.

    • by Nadaka (224565)

      From a recent article I read right here on slashdot, the telomer section of a strand of DNA is supposed to zip itself up as a 4 stranded section to keep the end from getting unzipped. Though I have no idea how accurate that actually is.

      • by Sockatume (732728)

        4-stranded DNA's definitely on the cards. Not sure if those are theoretical or experimental cards though.

  • Khm... (Score:2, Funny)

    by zrbyte (1666979)

    "break chemical bonds or ionize electrons"

    Don't know about breaking apart DNA, but I'm pretty sure they can't ionize electrons.

  • by cosmicaug (150534) on Friday October 30, 2009 @10:37AM (#29923633)

    Wait a moment, folk! We are talking about temporary separation of already uncoiled DNA (meaning, that it's probably under the process of being expressed, anyway) under very specific conditions as predicted by a computer model.

    This is not even an empirical observation: we don't know that any of this happens in a cell free in vitro system and how significant the effect is (if any), we don't know if it happens in a cell culture in vitro system and how significant the effect is (if any) and we certainly don't know that anything like this happens in vivo.

    Even assuming that you can create these precise conditions by an airport scanner (which seems rather doubtful), you certainly would not, in any way, be facilitating mutation in any appreciable sense*. All that you would be doing, theoretically, is to subtly alter patterns of gene expression for the few seconds it would take to walk through the scanner (basically, a very subtle regulatory effect). While you certainly can facilitate the development of cancer through such a mechanism (in fact, I'd argue that dysregulation of gene expression** at some points is simply required for carcinogenesis --yes, it can be caused by mutating proteins but these mutated proteins are almost invariably going to have direct or indirect regulatory functions***), such a dysregulation of gene expression would have be the prolonged, normal state of affairs of a cell for a cancer to actually happen. For this to be happening (in a worse case scenario) for as much as a few mere seconds can hardly even be called a dysregulation in any meaningful sense and much, much less have any effect, whatsoever, on carcinogenesis.

    If, on the other hand, some government agency is monitoring you 24/7 with these scanners, then you might have reason to worry****.

    * I would speculate that there's an infinitesimal chance that DNA might be more susceptible to mutations from not being as protected as it would be when paired but you have to realize that active regions of DNA get unzipped like this all the time so this effect, if it might be real, would be a drop in the bucket and utterly swamped by the background.
    ** For purposes of this discussion, what I mean by dysregulation of gene expression is the production of various protein products at inappropriate times or in the wrong amounts (either too much or too little of a protein).
    *** Whether the function is to induce cell division or stop cell division, or to induce cell death (apoptosis) or to evade cell death (and whether it is a direct or indirect effect on the preceding --such as mechanisms sensing DNA damage, loss of contact inhibition, etc.). While other factors which may not always be strictly regulatory do exist such as invasiveness, angiogenesis, telomerase function, etc (which often will also be regulatory by involving over or under expression); these factors need to happen together with a regulatory dysfunction for an actual cancer to happen because, basically, cancer happens when a lot of different sorts of things get screwed up at the same time.
    **** About adjusting your medication dose, that is.

  • All mutants sing along...

    Tiny bubbles [tiny bubbles] Make me warm all over With a feeling that I'm gonna Love you till the end of time

  • I'd also like to point out that the title of the post is sensationalistic and very highly misleading. Reading such a post, I would surmise that I'm about to read an article regarding the breaking of DNA strands which, though we have repair mechanisms to deal with such eventualities (which can have some curious effects in some non coding regions of our DNA, by the way), is a rather serious effect. I would not suspect from such a title that the article is talking about temporary strand separation of small str
    • Re: (Score:3, Informative)

      by Dunbal (464142)

      As a physician, I agree with you. Even sunlight can disrupt some of the bonds in your skin's DNA. And unless you are genetically susceptible due to lack of an enzyme (eg xeroderma pigmentosum [wikipedia.org] , you should be fine if you lead a normal life. However there is a positive correlation between excessive sunlight exposure (and thus DNA damage), pale skin, and skin cancer. No biological system is perfect - that's why disease and aging exist. So if you play roulette with your enzymes, you will eventually cause a

  • Huray!
    If people won't limit their flying for the climate, then let them do it for their DNA!

  • So We Use Terahertz"

    i'm sorry, but for the sake of just beautifully rhyming government supported advertising jingles, we just can't stop using these waves

  • by John Sokol (109591) on Friday October 30, 2009 @05:12PM (#29928975) Homepage Journal

    It sounds like this is probably far safer and more controllable then X-Rays or Gamma Rays for the treatment of Cancer.

    A big part of the idea with radiation treatments for cancer is to break the DNA of the cells such that they do not die instantly leaving a big hole, but instead are just prevented from successful reproduction. So as these cancer cells try to reproduce they die off instead. This happens slowly over time so that normal cells from healthy surrounding tissue can migrate over and fill in the treated cells as they die off.

    These THz waves could target just the DNA, killing those cells in a region and unlike X-Rays may have a lower chance of creating a new cancer from the radiation itself or damaging surrounding tissues.

Take care of the luxuries and the necessities will take care of themselves. -- Lazarus Long

Working...