I used to enjoy watching CSI (the original series), back when Gil Grissom (actor William Petersen) headed that fictional forensics lab. It was never the same after he left.
Anyway, one episode that I still remember involved a crime being committed by someone who was a genetic chimera: someone who had developed from an embryo formed when two fertilised eggs fused together. (There’s a fascinating blog post about chimeras over at damninteresting.com.)The upshot was that some cell lines in that indivdual’s body had one set of DNA, with other cells having a different genetic makeup. In such individuals it’s possible for different tissues to express genes from one or the other lot of DNA, something that’s called mosaicism (it’s also possible in all female mammals, where one or the other X chromosome is randomly inactivated when the embryo is at around the 1000-cell stage of development).
I was reminded of that episode when I saw this photo on Science Alert’s Facebook page (ah, the wonders of modern social networking!):
You’d need to look at the DNA from the white & ‘normal’ sides of this bird to be sure whether what we’re seeing here is definitely the result of a chimera displaying mosaicism. But isn’t it a stunning image?
herr doktor bimler says:
A 2004 episode, according to the Great and Powerful Google:
http://en.wikipedia.org/wiki/Genetic_chimerism_in_fiction
The X-chromosome mosaicism of female mammals turns up a lot in colour-vision research, because women carrying a colour-deficiency gene on one X chromosome end up with their retinas being more-or-less coarse patchworks of colour blindness. In the extreme case people can be red-green deficient in one eye and normal in the other. Then they must spend their lives hiding from the colour-vision researchers who wish to experiment upon them.
herr doktor bimler says:
Can we expect a post some time about the single mutation in the Icelandic horse breed that alters spinal nerve connections and allows them to run / walk in additional gaits?
http://www.nature.com/news/horse-gait-traced-to-single-mutation-1.11308
Grant Jacobs says:
Check out this face:
http://blogs.smithsonianmag.com/smartnews/2012/09/the-genetics-behind-venus-the-mysterious-two-faced-cat/
Grant says:
herr doktor bimler,
Toyed with writing about that myself a few days back but decided to let go. There’s a comment to the effect that it’s a sped-up walk, hence the smoother ride.
Alison Campbell says:
That’s a great photo 🙂 I will try to write something on that today & tie in hdb’s comment as well (I talk about the female mosaic colour-blind thing with the first-years).
herr doktor bimler says:
Since Alison wouldn’t blog about horse gaits and neuron differentiation, I had to do it myself.
Alison Campbell says:
So much blog fodder, so little time!