When humans migrated across the Bering Strait to N America during the last Ice Age, they brought along domesticated dogs. Soon after, black coats appeared in the native Gray Wolf population, caused by increased melanin due to changes in a single gene.
Known as the K gene (Japanese kurokami for ‘black hair’), the dark coat resulted from a variant introduced by interbreeding with dogs. Wolves carrying one or two copies of the KB version are black.
The frequency of black wolves increases from the Arctic to Mexico. Black coats are more common in regions with canine distemper outbreaks. It turns out that the K gene is a natural antibiotic (“defensin”) that confers immunity against distemper.
But the black coat variant also carries a fitness defect: few pups with 2 copies survive to adulthood. Gray-coated wolves produce larger litters and are more aggressive than black-coated wolves during territorial conflicts.
Scientists have been doing genetic engineering for some time. Heck, if you count breeding for traits, we’ve been doing it for centuries. But actual modification of DNA, changing the GCAT letters is pretty recent. But now scientists have gone past that. Scientists have added new nitrogen bases. They’ve added X and Y.
First, they had to make the new bases (d5SICS (X) and dNaM (Y)). They used RNA to make them in test tubes. Next, they had to get the X and Y into the cell. Using the favorite bacteria of mad scientists everywhere, Escherichia coli, they added a gene that would let the new bases through the cell membrane. Now that the e. coli had X and Y, they added a loop of DNA that contained a base pair of these bases, just one rung of the DNA double helix. For a week the bacteria multiplied, and each new cell had the DNA loop with the XY pair.
… but it will take a while. Back in 1900 there were billions of Chestnut trees in the US. Then, over 50 years, they died off, victims of a fungal blight. New trees would grow from the roots of the old, only to succumb themselves. But a few survived. And now it looks like scientists have managed to breed a resistant version. Next year 500 will be planted in Pennsylvania’s Westmoreland County.
For one, consider how much really needs to be the same. All of the work that cells do needs to be there. How to make the endoplasmic reticulum and other organelles is the same. Heck, our genome and a banana’s are about 50% the same. And the Neanderthals need to have the same body plan, bones, heart, liver, teeth, etc. The genes for building these things are going to be virtually identical–I expect them to be 100% the same.
But it’s how these genes are turned on and off that’s interesting. Most of our DNA isn’t in genes. We used to call it junk DNA. Now we’ve learned that there are things in the DNA that turn genes on and off. And when you turn a gene on can greatly affect the structure of the organs involved. Darwin’s Galapagos finches had different beaks depending on what kind of food they ate. But the genes for the beaks were the same. So how did they have different beaks? The genes were turned on at different stages of development while in the egg. If you turn the gene on sooner, you get a larger, stronger beak, good for cracking nuts open. Turn it on later, and you get a narrow, pointy beak, good for picking insects out of plants.
So, the genes for us and Neanderthals are mostly identical. It’s the switches that turn these genes on and off that’s different.
23andme wants to be the Google of personalized health care. They want to use your genome to sell advertising to you. They also want to be able to use your genetic information to sell to pharmaceuticals and insurance companies. I can easily see companies using this information to deny people service based on genetic potential. They feel that sifting through a database of your genes “does not constitute research on human subjects”. If it did (which it certainly looks like to me), then they would be subject to lots of rules and regulations.
Anyone who’s seen the movie GATTACA will recognize where this is going, and it isn’t pretty. Discrimination based on genetics is not a world I want to live in. Watch the movie, it’s good.
I’ve had my wisdom teeth removed. Wisdom teeth are the third molars, and our jaws are just too small to handle them. This means that when they come in, they don’t fit. So they end up pushing against the second molars, and you get impacted wisdom teeth, and have to have them pulled out. Why on Earth do we have these blasted things? Continue reading →