A question for the mad scientists out there

I just ran across this story about the world’s first transgenic dog, a beagle puppy with sea anemone DNA that causes it to fluoresce red under ultraviolet light. If memory serves, this same trick was done previously with rabbits (although I think the bunnies glowed green rather than red).

What I haven’t heard of yet is somebody creating a mammal that can glow without the UV light. Does anyone know if that would be technically possible, and if so, how much more difficult it would be?

12 thoughts on “A question for the mad scientists out there”

  1. Well, you can produce fluorescence with natural sunlight in various sea creatures. See here for a technical paper on the subject. Getting it to happen in a mammal would be trickier, because the light would have to be able to penetrate far enough into the skin for the fluorescent effect to last for a significant amount of time after the light source goes away.

    What needs to happen is:

    a. Photons of high-ish energy (the blue end of the visible spectrum, or near UV) get absorbed by the animal’s skin or hair.

    b. The energy is re-emitted as lower energy photons at a later time.

    To some extent this is what happens when we get sunburns. We absorb the near-UV that penetrates the atmosphere, and we later re-emit it as infrared light. A recently sunburned person looks *really* bright in an infrared scope.

    To get the effect you’re looking for, it’d require some pigment in skin or hair that absorbed blue or violet light, held the energy for long enough to matter, and then re-emitted the energy at a longer wavelength such as orange or red. I’m not a biophysicist, so I don’t know if any such pigment exists, but even if it doesn’t currently exist I imagine some clever team of biologists and biochemists and biophysicists can figure out a way to make it.

  2. we don’t have that many genes available to produce glow without uv (the firefly springs to mind, but that’s an on/off system with fairly complicated support). so it’s a more difficult problem b/c the parts it needs aren’t as readily available.

  3. Getting mammals to express one or another fluorescing proteins is a lot simpler than actually making them light up. Something like GFP (Glowing Fluorescent Protein, natch) can be stuck in the genome willy-nilly and as long as the stuff shows up in cells, your animal will glow under a blacklight.

    Luciferase, which is the protein that glows in a firefly’s butt, requires an actual support framework from the rest of the cell to activate in any sort of useful fashion. Also, as luciferase is oxygen-activated, you will need to find a way to deliver oxygen to it, or it to oxygen.

    As goofy as it sounds, having the protein be expressed in sweat would probably be the most-effective way of getting any sort of steady or detectable glow. You would want some sort of trigger to get the excretory system to dump the amassed bits of luciferase onto the surface of the skin. Fortunately, the advertising agents already gave us an answer – Gatorade! Well, Gatorade and bananas. The striking images of glowing sweaty athletes in the Gatorade ads of years past is probably not a bad way to visualize this idea. Don’t kiss our glowing subjects, though, luciferase tastes bad – and it will be all through their bodily fluids, including saliva.

    So, just imagine a sweaty glowing man, or horse, or hairless rat or terrier (both of which sweat) and you have your decidedly unappealing image of the future.

    1. The sweat idea is clever, but, yeah, less fun than a cat or dog that can light up its fur on command. To do that I guess you’d have to replace the hair with something living, or at least hollow it out and channel the luciferase into it, with a trigger linked to the purring or tail-wagging reflex…

      Don’t kiss our glowing subjects, though, luciferase tastes bad – and it will be all through their bodily fluids, including saliva.

      Something tells me there’d be a fetish for that.

  4. When I worked at NIH, the web page about rats as a reference animals for genetic research had a picture of a green-glowing rat. Unfortunately they are using a different image in their redesigned site.

  5. A lot of marine bioluminescence is caused by bacteria that have a symbiotic relationship with the fish/crustacean that relies on them. This is how, for instance, angler fish produce the glow in their head bobbins. I don’t see why this couldn’t be arranged with a mammal-bacterium relationship, though I don’t know the specific mechanics.

    I’m not a scientist, but I have a son fascinated by ocean’s twilight zone and abyss.

  6. Also fluorescent pigs were made (Manzini et al., 2008 PNAS, Genetically modified pigs produced with a nonviral episomal vector).

    Making them glowing red or green is just matter of the reporter gene choosed for transgenesis. Several colors can also be combined, the most famous example is the “brainbow” mouse in which each neuron is marked with a different color. See pictures in my blog: http://www.reportergene.com/2007/11/rainbow-and-brain.html

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