Comments on: Gene therapy gives full colour vision to colour-blind monkeys http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/ Mon, 26 Nov 2012 12:00:51 +0000 hourly 1 http://wordpress.org/?v=3.4.2 By: Nathan Myers http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4875 Nathan Myers Sun, 20 Sep 2009 23:27:15 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4875 Thank you, Håvard, that makes things much clearer. It means the squirrel monkeys' color blindness is much more closely analogous to that of humans. The difference appears to be that we have more than one analog of those opsin genes on each X chromosome, so that one fully functional chromosome suffices to provide color vision, where they need a different one on each X chromosome, if they're even so fortunate as to have two Xes. It's hard for people like "us" to look up facts like this, so your annotation is very helpful. Thank you, Håvard, that makes things much clearer. It means the squirrel monkeys’ color blindness is much more closely analogous to that of humans. The difference appears to be that we have more than one analog of those opsin genes on each X chromosome, so that one fully functional chromosome suffices to provide color vision, where they need a different one on each X chromosome, if they’re even so fortunate as to have two Xes.
It’s hard for people like “us” to look up facts like this, so your annotation is very helpful.

]]> By: Håvard http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4874 Håvard Sun, 20 Sep 2009 13:16:24 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4874 You write <i>"In squirrel monkeys, females see a more colourful world than males. While they have the same three opsins that humans do, males lack the gene for L-opsin and can't see red."</i> This is actually not correct. The L-opsin and M-opsin in squirrel monkeys are actually just alleles of the same gene, and they're located on the X chromosome. Well, actually there are three alleles, and they respond to slightly different wavelengths. The females are trichromates if they are heterozygous (and not all of them are), and the males are always dichromates - but they can have any one of the three alleles. doi:10.1016/S0042-6989(97)00405-7 That should answer Tulse's question. You write “In squirrel monkeys, females see a more colourful world than males. While they have the same three opsins that humans do, males lack the gene for L-opsin and can’t see red.”
This is actually not correct. The L-opsin and M-opsin in squirrel monkeys are actually just alleles of the same gene, and they’re located on the X chromosome. Well, actually there are three alleles, and they respond to slightly different wavelengths. The females are trichromates if they are heterozygous (and not all of them are), and the males are always dichromates – but they can have any one of the three alleles.
doi:10.1016/S0042-6989(97)00405-7
That should answer Tulse’s question.

]]> By: Nathan Myers http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4873 Nathan Myers Fri, 18 Sep 2009 19:49:56 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4873 John: You can experiment with better color vision just by wearing glasses with different-colored lenses. They don't need to be dramatically different. If you get two pair of sunglasses and swap lenses, you'll have two pair; wearing them on alternate days heightens the experience. John: You can experiment with better color vision just by wearing glasses with different-colored lenses. They don’t need to be dramatically different. If you get two pair of sunglasses and swap lenses, you’ll have two pair; wearing them on alternate days heightens the experience.

]]> By: adam http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4872 adam Fri, 18 Sep 2009 14:00:56 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4872 Tulse, I think they COULD get this to work in dogs. As mentioned in the post, a similar sort of procedure has been done in rats, which are normally quite colorblind. The particular method there involved breeding female rats to have a different allele for red on each x chromosome, if I remember correctly, but the method should still hold. All this implies that if you plugged in a fourth type of color signal into the brain, the mind could probably process it. Which is really cool. Tulse, I think they COULD get this to work in dogs. As mentioned in the post, a similar sort of procedure has been done in rats, which are normally quite colorblind. The particular method there involved breeding female rats to have a different allele for red on each x chromosome, if I remember correctly, but the method should still hold. All this implies that if you plugged in a fourth type of color signal into the brain, the mind could probably process it. Which is really cool.

]]> By: John http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4871 John Thu, 17 Sep 2009 23:52:31 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4871 Ed, I wrote Katie an email asking about the ratio of cones to rods, regarding color vision vs. night vision- I've got better night vision than anyone I know but I'm red green colorblind. I've always looked at is as a trade-off. Her replies are below. Note where she corrected you. "Katherine I'm just a layman but a story about the gene therapy giving additional color vision to male squirrel monkeys caught my eye. It stated that you've been able to add color perception by adding cone cells. I'm red green color blind and have theorized that my eyes have more rods than most folks, that I've been enjoying better night vision at the cost of some of my color vision. Have you experimented any with light perception with your monkeys? Does the additional cone add some color perception at a cost? Just curious and thanks for your time, John Hi John, Thanks for the email. What you describe about having better night vision is actually a fairly common observation made by people with color vision deficiency. It has also prompted scientists to test for this in human subjects; however, the consensus seems to be that no one has been able to conclusively demonstrate that people with colorblindness have any advantages under low lighting (scotopic) conditions. (I have attached a paper describing some of this work.) We have not specifically tested for this in our monkeys, although it would be interesting to know. Because we only added a single gene that specifically changed the response properties of a subset of the cone photoreceptors (not the rods), and we have not done anything to change the overall number of rods vs cones, it does not seem likely that the new color vision was gained at the loss of some other aspect of vision. [By the way, some of the articles have incorrectly reported that we injected “new cells” into the eye; what we actually injected was a virus vector carrying a gene – when it was taken up by the cone cells, a new visual pigment was produced within those cones.] Thanks again, Katie Katie, So, the cells you modified, are they now dual-color perceptive? Is there a way to tell? Has perception of the other colors changed? For instance, has blue or yellow perception lessened? I'm excited to hear that there's a prospect of full color vision, especially if I don't have to trade off my night vision. Have you played any with the so-called fourth cone that some women possess? Thanks again! John John, The subset of cones that are transfected by gene therapy co-express two pigments – green and red. Overall, this gives those cells a different spectral sensitivity (different response characteristics to colored light) compared to the original blue cones and green cones in the monkeys’ retinas. Normal color vision requires three different types of cone; what’s interesting is that co-expressing a red pigment within some of the green cones was sufficient for the monkey’s brains to recognize them as being a “third cone type.” Therefore, even though we only injected a single gene, it did result in producing a third type of cone, as far as the visual system was concerned. I hope this is helpful and not too confusing. The treatment did not have any obvious effects on their ability to see blues and yellows, although we are in the process of testing this more thoroughly. Drs. Neitz have thought a lot about the tetrachromacy idea, and here is link to a 2006 article that describes a little about it: <a href="http://www.post-gazette.com/pg/06256/721190-114.stm" rel="nofollow">http://www.post-gazette.com/pg/06256/721190-114.stm</a> You may also be interested in checking-out our website: <a href="http://www.neitzvision.com/" rel="nofollow">http://www.neitzvision.com/</a> The paper she referred to is: "Is Color Vision Deficiency an Advantage under Scotopic Conditions?" by Matthew P. Simunovic, Benedict C. Regan, and J. D. Mollon (she sent a .pdf) Cheers! Ed, I wrote Katie an email asking about the ratio of cones to rods, regarding color vision vs. night vision- I’ve got better night vision than anyone I know but I’m red green colorblind. I’ve always looked at is as a trade-off. Her replies are below. Note where she corrected you.
“Katherine
I’m just a layman but a story about the gene therapy giving additional color vision to male squirrel monkeys caught my eye. It stated that you’ve been able to add color perception by adding cone cells. I’m red green color blind and have theorized that my eyes have more rods than most folks, that I’ve been enjoying better night vision at the cost of some of my color vision. Have you experimented any with light perception with your monkeys? Does the additional cone add some color perception at a cost? Just curious and thanks for your time, John
Hi John, Thanks for the email. What you describe about having better night vision is actually a fairly common observation made by people with color vision deficiency. It has also prompted scientists to test for this in human subjects; however, the consensus seems to be that no one has been able to conclusively demonstrate that people with colorblindness have any advantages under low lighting (scotopic) conditions. (I have attached a paper describing some of this work.)
We have not specifically tested for this in our monkeys, although it would be interesting to know. Because we only added a single gene that specifically changed the response properties of a subset of the cone photoreceptors (not the rods), and we have not done anything to change the overall number of rods vs cones, it does not seem likely that the new color vision was gained at the loss of some other aspect of vision. [By the way, some of the articles have incorrectly reported that we injected “new cells” into the eye; what we actually injected was a virus vector carrying a gene – when it was taken up by the cone cells, a new visual pigment was produced within those cones.] Thanks again, Katie
Katie, So, the cells you modified, are they now dual-color perceptive? Is there a way to tell? Has perception of the other colors changed? For instance, has blue or yellow perception lessened? I’m excited to hear that there’s a prospect of full color vision, especially if I don’t have to trade off my night vision. Have you played any with the so-called fourth cone that some women possess? Thanks again! John
John, The subset of cones that are transfected by gene therapy co-express two pigments – green and red. Overall, this gives those cells a different spectral sensitivity (different response characteristics to colored light) compared to the original blue cones and green cones in the monkeys’ retinas. Normal color vision requires three different types of cone; what’s interesting is that co-expressing a red pigment within some of the green cones was sufficient for the monkey’s brains to recognize them as being a “third cone type.” Therefore, even though we only injected a single gene, it did result in producing a third type of cone, as far as the visual system was concerned. I hope this is helpful and not too confusing.
The treatment did not have any obvious effects on their ability to see blues and yellows, although we are in the process of testing this more thoroughly.
Drs. Neitz have thought a lot about the tetrachromacy idea, and here is link to a 2006 article that describes a little about it: http://www.post-gazette.com/pg/06256/721190-114.stm
You may also be interested in checking-out our website:
http://www.neitzvision.com/
The paper she referred to is: “Is Color Vision Deficiency an Advantage under Scotopic Conditions?” by Matthew P. Simunovic, Benedict C. Regan, and J. D. Mollon (she sent a .pdf)
Cheers!

]]> By: Nathan Myers http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4870 Nathan Myers Thu, 17 Sep 2009 08:23:50 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4870 It seems as if you could get much of the way to mantis shrimp eyes (i.e., distinguishing various polarizations) with cleverly designed contact lenses. It seems as if you could get much of the way to mantis shrimp eyes (i.e., distinguishing various polarizations) with cleverly designed contact lenses.

]]> By: Snoof http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4869 Snoof Thu, 17 Sep 2009 03:44:37 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4869 I want some mantis shrimp eyes, personally. I want some mantis shrimp eyes, personally.

]]> By: Tony P http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4868 Tony P Thu, 17 Sep 2009 02:53:14 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4868 We already have things that see in UV and infrared. They're digital cameras. Mine picks up UV and IR very well. And it's only a little Xacti C40. We already have things that see in UV and infrared. They’re digital cameras.
Mine picks up UV and IR very well. And it’s only a little Xacti C40.

]]> By: Katherine http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4867 Katherine Thu, 17 Sep 2009 02:11:43 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4867 Greg, are you completely red-green colourblind, or just partially? Do you have the most common form of red-green colourblindness, or a lesser-known kind? I do not profess to be an expert, but I would think that there are a whole range of colourblindness options possible. Also my dad is colour-insensitive but on the dot tests (where you see a number if you have normal vision) he presents as red-green colourblind. We know he isn't really because we turned up the colour on the TV when they were showing the tests and he presented as having normal vision. Greg, are you completely red-green colourblind, or just partially? Do you have the most common form of red-green colourblindness, or a lesser-known kind? I do not profess to be an expert, but I would think that there are a whole range of colourblindness options possible. Also my dad is colour-insensitive but on the dot tests (where you see a number if you have normal vision) he presents as red-green colourblind. We know he isn’t really because we turned up the colour on the TV when they were showing the tests and he presented as having normal vision.

]]> By: August Pamplona http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4866 August Pamplona Thu, 17 Sep 2009 01:53:35 +0000 http://blogs.discovermagazine.com/notrocketscience/2009/09/16/gene-therapy-gives-full-colour-vision-to-colour-blind-monkeys/#comment-4866 <blockquote>Unfortunately, the architecture of the retina does not accommodate more than trichromatic vision.</blockquote> Don't be so sure: <a href="http://en.wikipedia.org/wiki/Tetrachromatism#Possibility_of_human_tetrachromats" rel="nofollow">http://en.wikipedia.org/wiki/Tetrachromatism#Possibility_of_human_tetrachromats</a>

Unfortunately, the architecture of the retina does not accommodate more than trichromatic vision.

Don’t be so sure:
http://en.wikipedia.org/wiki/Tetrachromatism#Possibility_of_human_tetrachromats

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