Tuesday, May 4, 2010

Scientists Rebuild Wooly Mammoth Blood

Via FoxNews.com -

Mammoths adapted to their new, colder home partly by evolving a "thick, huge pelt," and down-sizing their ears compared with their warmer-dwelling relatives. "Their ears were tiny, like dinner plates," Campbell said, referring to the cold-adapted mammoths.

But Campbell suspected that the mammoths also could have had blood that was better adapted to work in the cold, like many Arctic mammals alive today do.


Campbell wanted to see if mammoths were also able to evolve a specialized form of hemoglobin that would keep working at cold temperatures and allow them to conserve body heat.

There was just one problem: mammoths are extinct.

"We can't take a frozen blood sample," Campbell explained.

Instead, Campbell and his colleagues used genes extracted from mammoth remains to recreate and examine mammoth hemoglobin.

"We had to bring it back to life," Campbell said.

The team extracted DNA from a 43,000 year-old Siberian mammoth specimen and had the portion of it that holds the instructions for hemoglobin sequenced.

When Campbell saw the results he said could tell that "there were some changes that were very suggestive of physiological processes" that meant the mammoths did indeed evolve a specialized cold-adapted form of hemoglobin.

The changes amounted to just 1 percent of gene region that contained the instructions for hemoglobin, "but one of those changes is profound," Campbell said. That change "is going to make them adapted to cold."

To find out if these gene changes actually produced a different type of hemoglobin, the team used a method that has been used to make human hemoglobin. The method involves putting the specific genes into E. coli, which will read the human, or mammoth, DNA like its own DNA and produce the substance in question.

But mammoth DNA samples retrieved from frozen specimens are very damaged, so Campbell and his team first turned to the mammoth's closest living cousin. They got the DNA and RNA (the stuff that holds the instructions for proteins in cells) from a living Asian elephant and put them into E. coli.

And sure enough, "these E. coli made Asian elephant hemoglobin," Campbell said.

Once the Asian elephant hemoglobin checked out, the team could try mammoth hemoglobin. To do this, they used Asian elephant RNA and a process called site-directed mutagenesis, which involves changing all the individual points in the RNA code that are different between the Asian elephant and the mammoth, effectively turning Asian elephant RNA into mammoth RNA. The newly made mammoth RNA is put in the E. coli, which spits it out what is essentially mammoth hemoglobin.

Campbell said this hemoglobin would be exactly the same as if he had taken a time machine back 43,000 years and drawn blood straight from the animal. "I can study it as if I had a fresh blood sample from that animal," he said.

The team compared the Asian elephant and mammoth hemoglobin and "we found that they're radically different," Campbell said. Just as Campbell had suspected, the mammoth hemoglobin doesn't need as much energy to offload oxygen as the Asian elephant hemoglobin does.

Interestingly, the mammoth DNA had two separate mutations that are different from those seen in mammals today.

"They used a completely different" way to solve the hemoglobin problem to adapt to the cold, Campbell said.

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