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[Comments] (3) A Survey of Mutant Miceology, and Other Topics Biological: Today was more looking at interesting things and less at apartments. We met up with Andy Schile! I hadn't seen him for almost ten years, but there he was, or at least a convincing animatronic simalcrum. Together we went to the Natural History Museum. We saw the special exhibit on the life of Darwin, which was cool: they had a bunch of skull casts for all the known hominids, arranged in an evolutionary tree. Actually the whole museum was arranged around evolutionary trees. One exhibit took up the entire fourth floor with the Vertebrates' Greatest Hits, organized cladistically.

We walked through Central Park to a Japanese restaurant that Andy likes. While we ate, he brought us up to speed on his research into the creation of mutant mice. He creates a mutant mouse by taking a mouse embryo and replacing the DNA inside some of its stem cells. The mouse develops with two sets of DNA (it's a "chimeric" mouse), and you check the color of its coat.

The mouse embryo would naturally have, say, a white coat, and the new DNA is for a mouse with a black coat. If the chimeric mouse has a dark coat then it's a good bet that most of its cells came from the modified stem cells. Specifically, its sex cells probably came from the modified stem cells. This means you can breed it with another chimeric mouse and get a mutant mouse.

A mutant mouse comes from a modified sperm and a modified egg, so it's not a chimera. It's what you would have gotten if all the cells of the original mouse had come from modified stem cells.

Here is the part I'm not as clear on. Andy is trying to breed mutant mice which have a certain gene truncated. The truncated gene will not be able to produce a certain protein. The protein is in charge of attaching a chemical tag to cells that need to be garbage-collected (or maybe the protein is, in fact, that chemical tag; I'm not sure). So if Andy's mad plan succeeds, these mutant mice will not be able to engage in cell death.

At this point in the pop science article I would talk about the applications of this revolutionary new technique for "the fight against aging" and leave it at that. However I have two other things to tell you. The first is that these mice will not be immortal just because they can't kill their own cells. They will probably get some sort of anti-cancer and die (I speculated as such and Andy didn't correct me). The second thing is that this is not a really new ability. You can already create a mouse whose cells don't die by giving the mouse a new gene, one copied in from a virus. I don't remember what the virus gene does, but obviously it works differently from Andy's technique; I think it might prevent cells from accepting the garbage-collection tag. Andy's technique has the same end result, but it doesn't require genes from other organisms. Once he gets some mice whose cells behave in an interesting way (or he fails in an interesting way), he can write his dissertation and he's Dr. Andy.

I wrote this mainly as a writing excercise, but it's a pretty interesting set of hacks and I never really understood how genetic engineering works, so maybe you'll find this interesting too. Rewiring mice stem cells sounds like a pretty dull job to me, but Andy likes it. I have more interesting stuff to write from our conversation, such as the operations you can perform on a gene or genome, and when you can copy a gene from one species to another. I will write this other entry if people are interested, or if I am bored.

In the museum I told Andy lots of trivia about prehistoric animals and evolution which I'd think he would know, as a biology major, but he was appreciative of the trivia. Maybe he was just humoring me. For instance, they had an Irish elk skeleton. I told him how biologists used to think the Irish elk demonstrated that evolution could get stuck in a rut, with the male Irish elk getting larger and larger antlers long after it ceased being any kind of advantage. This continued until the males couldn't lift their heads anymore, leading to extinction.

This page yields some more Irish elk trivia. For instance, the antlers of the Irish elk are not particularly large for its size. They just look abnormally large because the animal is so big. And the Irish elk also figured in a more prominent scientific argument: whether or not animals could go extinct at all.


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