By reversing evolution, scientists may be able to transform chickens into dinosaurs one step at a time.

You may remember that in Jurassic Park, scientists sequenced some dinosaur DNA from a mosquito trapped in amber. They made a copy of this DNA, filled in the gaps with frog DNA and then created a dinosaur.

Although cool, we're not likely to get dinosaurs this way in the near future for a bunch of different reasons. The biggest for now (besides not having any dinosaur DNA) is that we can’t clone anything bigger than a bacterium with just a piece of DNA. To clone a multi-celled creature like a dinosaur, we need frozen or even better, live cells.

While this might be possible for some extinct animals including mammoths, 65 million years is just too long to find any frozen or viable cells. But there may be another way to one day create Jurassic Park. By messing with a chicken’s genes.

Current theories are that birds evolved from dinosaurs. This means that all the information for making a dinosaur was contained in bird DNA at one time. The trick is to figure out what this dinosaur DNA looked like and to change bird DNA accordingly and/or to unlock any hidden dinosaur DNA that may still be in bird DNA.

After 65 million years you might think all traces of dino-DNA would be lost in birds. Surprisingly, you’d be wrong. It looks like there is still some T-rex lurking in a chicken’s DNA.

In the last decade, scientists have been able to make chickens look a bit more dinosaur-like by changing how the chickens use the genes they already have. For example, they have been able to make a chicken’s tail look a bit more like a dinosaur’s.

A big difference between birds and dinosaurs is that dinosaurs have much longer tails. But this doesn’t hold up in a chicken embryo.

At a very early stage of development, chicken embryos have what looks like a very reptilian tail with 16 vertebrae. Later in development, though, most of the vertebrae disappear until only five are left.

What this means is that if scientists can figure out how to keep the vertebrae from disappearing, they might end up with a long tailed chicken. And they’ve actually managed to sort of do this already.

By changing when certain genes are turned on or off, they have managed to create a chicken with a tail that has eight vertebrae. Not quite a dinosaur but a step in that direction.

They have also been able to create a chicken with teeth. And even a snout! All of this without fundamentally changing a chicken’s genes but instead changing how they are used.

Now they probably won’t be able to make the chicken-dinosaur transition simply by changing how chicken genes are used. There are bound to have been some significant changes in certain key genes that will have to be replicated to really make a dinosaur. And for that we’ll need to figure out what dinosaur DNA looked like.

But still, we can make a lot of progress towards making a dinosaur by simply using the toolkit of current bird genes. In the end, we’ll probably be able to recreate something very much like a dinosaur. The question will then become whether we should.

QUEST story on how scientists can figure out ancient DNA from modern DNA.

Maybe a clone of this guy will wander the Earth one day.A new study shows that scientists can clone a mouse that has been dead and frozen for 16 years. If they can apply what they've learned to a mammoth that has been dead and frozen for over 10,000 years, then maybe my kids can ride a mammoth one day. Or at least my grandkids can.

You Need More than DNA to Clone

Cloning isn't as simple as was shown in Jurassic Park. You can't take DNA and make a clone from it. Instead, you need an intact nucleus. And ideally, an intact nucleus in an intact cell.

The nucleus is where DNA is kept in our cells. The DNA is stored and packaged there in a way that only Mother Nature can do (for now). We can’t take our 6 feet of DNA and cram it into the tiny space of the nucleus.

Cloning 101.As I said, right now cloning uses intact cells. Here's how it works:

1) Take a cell from the animal to be cloned
2) Remove the nucleus from an egg (this is called an enucleated egg)
3) Fuse the two cells and let it divide a few times in a Petri dish
4) Implant the growing embryo into a surrogate mother
5) If everything goes well, a clone is born

This procedure requires living intact cells to be used. The problem with a frozen animal cell is that it is dead and ice crystals have torn it apart. It is not possible to fuse a beat up dead cell with an enucleated egg.

Cloning Using Frozen Cells

What the researchers in this new study did was change the protocol a bit. Instead of fusing two cells, they harvested nuclei from the frozen cells and injected them directly into the enucleated egg.

When they tried to clone the mouse that had been frozen for 16 years this way, it didn't work. But they managed to get 4 clones by adding an extra step. What they did was to make embryonic stem (ES) cells from the frozen mouse and use those cells to make a clone.

Basically they cloned the mouse but then instead of putting the embryo into a surrogate mother, they harvested its ES cells. Then they used the nuclei from these cells to create a clone in the usual way.

So we can now clone a long frozen mouse. The next step will be to try to clone an extinct animal like a mammoth.

Cloning a Mammoth is Trickier than a Mouse

Mammoth cloning will be no walk in the park. First off, we don’t have any mammoth eggs or cells to use. We'll have to use elephant ones. Hopefully, elephant eggs and/or cells will be compatible with a mammoth's nucleus. ( But there is some concern they they might not be compatible.)

Second, elephants are a lot harder to work with than mice. The experiments in this study used thousands of eggs to get a few clones. I don’t know enough about elephant biology but it seems like you'd need a lot of elephants to get that many eggs.

But this is definitely the first step in resurrecting long dead animals. For now we'll have to focus on the frozen ones. Maybe in the future researchers can figure out how to clone animals stored in formaldehyde. Or from pelts. Then we can start reviving species we humans have managed to kill off over the years.

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