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Single Gene Gives Mice Three-Color Vision
Posted by
kdawson
on Sat Mar 24, 2007 02:53 PM
from the colors-you-can't-see dept.
from the colors-you-can't-see dept.
maynard writes "A study in the peer-reviewed journal Science shows that mice transgenetically altered with a single human gene are then able to see in full tri-color vision. Mice without this alteration are normally colorblind. The scientists speculate that mammalian brains even from animals that have never evolved color vision are flexible enough to interpret new color-sense information with just the simple addition of new photoreceptors. Such a result is also indicated by a dominant X chromosome mutation that allows for quad-color vision in some women." A sidebar in the article includes a nice illustration of what two-color vs. three-color mice might perceive.
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Oblig. (Score:2, Funny)
Re:Oblig. (Score:5, Funny)
-L
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Re:Oblig. (Score:4, Funny)
Do you think she'll notice me ?
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Actually, there is such a thing as a pentachromat [wikipedia.org]. She's female. And yes, she's a bitch. I have personally met her, fought her, and got my ass kicked.
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Here is a picture of the modified mice (Score:2, Funny)
Quad = 4?? (Score:5, Funny)
Are you kidding me? You know darn well that women can see at least 75 shades of off-white...
Re:Quad = 4?? (Score:5, Funny)
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Question I couldn't get from the article (Score:5, Interesting)
Re:Question I couldn't get from the article (Score:4, Informative)
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Re:Question I couldn't get from the article (Score:5, Informative)
Don't thank god for that, thank natural selection. A virus that impairs its host's vision is not going to get much time to reproduce itself.
Parent
Re:Question I couldn't get from the article (Score:5, Interesting)
The latter is the case. Your eyes are destined to suck forever. You can't see infrared or ultraviolet, you can't see like a hawk, nor can you get the lungs of a bird, the electro-sensing power of a platypus, ability to freeze solid like a toad, smell things as well as a dog, hold your breath like a whale. Even simply fixes like giving humans the ability to make their own vitamin C (every mammal has that save great apes and guinea pigs). No fixing the mammal eye so the all the blood and nerve don't run in front of the lens. No fixing the recurrent laryngeal nerve so that it goes from the brain straight to the larynx rather than looping around the aortic arch for no reason at all.
We could however, perhaps give such changes to our kids, those ungrateful little snot-filled twerps. You'll have to live being a social thin-haired ape who can play with fire and kill just about anything after making the tool for the job.
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Yes and no (Score:5, Informative)
Yes.
It depends off your target site, but yes it is possible.
- You can replace bone marrow (remove a mutated one that led to cancer, and put another one (given from a relative) that is exempt of the broken gene that lead to the cancer). As you are modifying stem cells (blood cells precursors) the modification is rather permanent. And as the newly produced white blood cells are always re-trained after creation they won't consider your body as foreign so you won't have immune system rejection (graft vs. hosts in this case). And as a bonus, because bone marrow cells have homing capabilities, they're as easy as a blood transfer to inject. But the problem is that, during the time between when you radiated the old marrow to kill the cancer and when the newly injected one has finished recreating white cells, there's a window during which the organism is defenseless against infections.
- Viruses are small things that basically work by injecting their genetic information (DNA or RNA) inside a host cell. Scientist can assemble small virus like things that use the virus shell and thus are able to inject their material, but inside they contain the gene you need to add for the therapy. As far as I've heard there were attempt to use such a system to treat mucoviscidosis (by injecting a gene to help produce working chloride channels). It is administered as a spray. The problems are (beside the high cost of such a method) that the spray only reach the supperficial layer of cells in the bronchus. These are differenciated cells that don't multiply anymore, they only do their work until they die off and fall out. The precursors are deeper and not affected by the therapy. Thus the effects aren't permanent. Plus, after some time the hosts immune system ends up discovering those modified virus and/or infected cells, considers them as foreign and develops antibodies against them. Thus the therapy gets ineffective after some times. Thus the whole idea was scrped and now we mostly use drugs that are cheaper, makes the cells work using the gene they already had before (other ion channels - carbocystein) or directly dilutes the secretions (acetylcystein), and whose effect doesn't diminish with time (thus they are much more effective at reducing the speed of degradations of lungs and buying time before lung transplantation gets necessary).
No. /before/ the brain and the retina gets wired. The colour perception capabilities develops when the nervous fibres grow and connect to different population of receptors.
Transgenic mice = before birth gene modification.
For the mutation to work, it has to happen
You can't 'cure' colour-blindness with gene therapy alone.
Technically speaking, there are virus that can infect retina before birth. But they would be much more difficult and expensive to produce, plus they can have bad side effects, and they are harder to control if they did inject their genes. Also the whole stuff is less ethical for the poor mice. Right now, you modify the mice at the stage of either zygote (1 single cell) or not-yet feconded gamete. You let the zygote do a couple of division, you get one of the dozen cell and check it the gene is still in place. If it is, you implant the stuff in a mother mouse. With the virus way, you have to inject the virus into a mother mouse while she still carries the baby mice (and hope that there won't be too much side effects - inflamation and such - for the mother or the mice she carries), then once the baby mice are born, you have to screen them to see which one carry the new gene (and has them into the eyes. The virus can target several organs, and won't necessarily infect the mice's eyes. I don't know, but maybe removing one of the eyes could be the only solut
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possible use in humans? (Score:5, Interesting)
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Can the human eye focus UV light, or would the ability to perceive it simply add more noise and glare?
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Human tetrochromats do not see UV (Score:2)
More importantly, they can't see in IR. To me, having heat vision would be way cooler.
Could people handle four-color vision? (Score:2)
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Squant (Score:3, Funny)
Martian colours (Score:5, Interesting)
The interesting implication here is that the GM mice's brains apparently developed with the ability to process the new colours. It would be fair to assume that ordinary mice's brains did not even contain the "concept" or "perception" of red hardwired in, since what would the point be?
Thus, if the converse is true, and human brains develop the same way as mice's, it could be assumed that the brains of people with the *physical* inability to detect certain colours from birth would never develop the mental concept/sensation of those colours. (*) But then, now does this explain "Martian colours"?
(*) (If you're having trouble understanding what I mean, try to imagine what ultraviolet "looks" like. Darklight (UV lamp) special effects don't count; that's *visible* light produced when UV hits special fluorescing material. And you can't "cheat" by imagining in terms of false colours (since that, by definition, is *converting* UV to visible-range colours). No, I want you to try to imagine what colour actual UV light would look like... and you'll fail because you've never directly seen UV light, and the concept isn't wired into your brain).
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The simple explanation, that doesn't require hardwiring colors into the brain (which raises extremely tricky questions with both your synesthaesia guy and your mouse), is that the brain, or even eye, which does a surprising amount of visual processing, recombines the individual cone information it gets into at least some approximation of a full spectrum
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If he couldn't differentiate colours then how could he be said to be "experiencing colours" (albeit through synesthaesia) -if he was experiencing the colours in any non-random way
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Interestingly enough (to me) if the color on the edge of my vision is a significant light source, say, an LED in
Re:Martian colours (Score:4, Interesting)
It seems quite possible a mouse's brain could classify groups of cones, especially since they would be obvious from birth on.
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Quit with your synesthaesia, if his photoreceptors are only capable of picking up a greatly limited spectrum of colors there's no magical 6th sense which will tell him what the other colors are.
That's not what I said.
Synesthaesia is the blending of senses, such that (e.g.) hearing a certain sound may trigger the sensation of taste or colour. In this case, the guy couldn't actually see the "missing" colours (via his eyes) at all. Yet he could "experience" the sensation of those colours via his synesthaesia.
Still no proof of 'full' spectrum vision (Score:5, Interesting)
So their claim that the GMs mouses brain really processed the red light signal different from the green might be a bit over the top.
(hmm thinking about it, if the GM mouse cannot discern between red and green, there might be a certain redlight intensity where their scores would drop significantly, while the controls would score better. If you cannot find that, my hypothesis is wrong and their claim is right. Now lets see if I can find if they did that test...)
Re:Still no proof of 'full' spectrum vision (Score:4, Insightful)
So, you can't even say that what we see as "red" is actually red at all. When a certain wavelength of light hits a bunch of cones, they each send their own response to that stream of photons to the brain, encoded as an SML signal, so to speak, and red is just some specific SML signal. Our brain then interprets the S, M, and L information and composes an "image" of the color. A lot of L and a little bit of M and S looks like red.
So, if the M and L cones are processed by the same neuro-circuits, then yes, they just saw an increase in intensity. Stimulation of an M or L cone would cause the same area of the brain to respond, and since red is more towards L, then that area of the brain would see more activity than it normally does in the non-GM mice, assuming M and L signals activate the same neurons.
However, if the M and L cone data are processed in different areas, then I would believe that they indeed see different colors.
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Commence with the "new overload" jokes (Score:2)
Colorblind posters wanted (Score:2, Interesting)
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I probably have protanomaly [wikipedia.org]. Distinguishing red and green isn't a problem at all, but I do see different shades of red and brown to other people (e.g. cheap Rubik's cubes with a darker shade of red than the original look maroon to me.) On one occasion, a normal sighted birdwatcher pointed out a Scarlet Robin in a tree that I couldn't see until I looked at it through binoculars, when the bird "popped out" with it's bright red breast.
this makes sense (Score:2, Funny)
A sidebar in the article includes a nice illustration of what two-color vs. three-color mice might perceive. [hhmi.org]
... thus explaining why mice show no outward tendencies towards jealousy or violence, and behave in a highly cautious manner at all times.
Dicromats (Score:2)
No. They are dicromats.
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of colors a human trichromat can. There's pedantry and then there's being an ass.
http://en.wikipedia.org/wiki/Color_blindness [wikipedia.org]
The Ducks Win It! (Score:5, Interesting)
Maybe we can put them to work testing monitors. Your garden variety graphics card and monitor are already capable of producing more colors (4.28 million or some such) than humans can differentiate (3 to 3.5 million).
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Re:True colour (Score:5, Interesting)
Violet is especially tricky. Its wavelength is shorter than blue, but in addition to stimulating your blue cones, your red cones are also slightly sensitive to it. The camera, however, sees the pure, very deep blue. Then, when it goes to display it on the LCD, it only turns on the blue pixel instead of the blue and a little red.
Another thing that people don't generally notice is that the RGB pixels or phosphors don't match up perfectly with everyone's cones. The only way I can think of to have faithful color representation is to have one "pixel" on both camera and display that is sensitive to and can emit any visible frequency of light, with perfectly flat response. IOW, maybe flying AI-controlled cars will have a camera/display like that.
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Re:True colour (Score:5, Informative)
This doesn't make any sense. Red cones are not sensitive to blue light. Here is a diagram [utah.edu] showing the sensitivities of of the three cones (S, M, and L or Blue, Green and Red) in our retina whose signals combine to create color.
Our perception of color comes from the combination and comparison of the stimulation of three different cones, each maximally sensitive to different wavelengths. The output of the cones gets combined in what are called opponent pathways, one is Red-Green, and the other is Blue-yellow. The Red-Green pathway compares the output of the Red and Green cones and the Blue-yellow pathway compares the output of the blue cone with the sum of the red and green cones. This is why you will never see a color that is reddish-green or blueish-yellow (see nick) at least in the additive sense that red+blue=violet and yellow+blue+green.
So why does extremely short wavelength light appear to contain a reddish component? I don't believe that anyone knows the answer to that yet. But the hypothesis is that somewhere along the path from cone to cortex the input from a blue cone and red cone combine which turns our perception of an extremely short wavelength light into a combination of short wavelength light (blue) and extremely long wavelength light (red). So our sensation of color becomes a continuum that loops back on itself as opposed to our sense of pitch (which is also frequency or wavelength).
Interestingly people who have had their lenses removed are somewhat able to perceive ultraviolet light. This is because the lens ordinarily blocks UV light and blue cones are sensitive to UV light but very little ever penetrates to the retina normally. Apparently they see it as lilac.
Many mammals, fish, birds, insects, and reptiles (basically everyone except us) are able to see UV light as well. It's a good that we can't for two reason. One is that there is more chromatic aberration at shorter wavelengths. Basically blue light bends more than red light. This makes focusing more difficult. Also, more importantly, UV light damages DNA which is a very, very, bad thing. This [handprint.com] is a good resource for learning more.
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> spectrum.
Please go and read a good article on color vision.
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