My article comes from the LA Times by way of sfgate.com, and reports that researchers have mapped the rhesus macaque genome. This is very useful to the field of genetics beyond just being one more known genome because it allows us to compare humans, chimpanzees (genome mapped 2 years ago), and macaques to get a more complete picture of what and when certain genetic additions or changes to the primate line might have occurred. Chimpanzees split off from humans about 6 million years ago, and we share 99% of our DNA, whereas macaques split off 25 million years ago and we share 93%. But even within these shared genes, scientists found, there are changes in phenotype, which to me was the most interesting part of the article.
Scientists found several of the genes that, when mutated in humans, cause very harmful or even fatal genetic diseases-- this includes the mutations that cause phenylketonuria, cystic fibrosis, and genetic blood diseases-- in macaques. This is no great surprise. The more stunning fact was that the same mutations in macaques are not harmful! Phenylketonuria is a disease in which individuals cannot metabolize the amino acid phenylalanine, and as a result it builds up in the body and causes brain damage; if macaques can live normally with a mutated copy of the gene, they must either have evolved insensitivity to phenylalanine or avoid it completely in their diets (as humans with the disease are forced to). Cystic fibrosis is a recessive genetic disease in which chloride channels form incorrectly as a result of a mutation in the CFTR gene, which encodes these channels. It leads to a host of terrible symptoms, including trouble breathing, lung infections, and many, many more. The article did not mention whether scientists have any idea why mutated CFTR genes do not affect macaques, but it is certainly interesting.
Finally, the researchers found that macaques have about three times as many immune system genes as we do, which is significant given that macaques are a popular animal for vaccine testing. The article also mentions that several other primate species, including the marmoset, gorilla, orangutan, and gibbon, are being sequenced. It will be fascinating to see what details these genomes can provide about primate evolution.
The full article can be found at http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/04/13/MNGVGP7VEU1.DTL&hw=evolution&sn=004&sc=448. Sorry, my browser won't let me link to a single word to make it simpler and prettier to get to the URL...
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the larger number of immune system genes is interesting...especially if we consider humans to be more evolved than macaques. i wonder why that is the case. for instance, is alternative splicing during antibody production a novel mechanism only found in humans? No right?
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This also makes me think about the idea of "use and disuse." Since we have so much more preventative measures to keep bad stuff (for a lack of better term) away from us, are we going to eventually lose our immunity to certain viruses/bacteria?
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