Reconstructing a Mammoth Hemoglobin

The reconstruction of a Mammoth just might be possible! Well not quite yet, but researchers are getting closer and closer. A team led by Kevin L. Campbell of the University of Manitoba in Canada, has reconstructed the Mammoth’s hemoglobin. People usually associate these furry creatures with the frozen arctic; however, they actually originated in the tropics about seven million years ago. Their split from the elephants is what led them to adaptations in the cold northern latitudes. The split occurred in physical appearance such as smaller ears, a thick furry coat, and in protein structure such as hemoglobin.

Hemoglobin is the protein that is responsible for the transport of oxygen from the lungs to the rest of the body. It is an assembly of four globular protein subunits which are made of globin chains and these are tightly associated with a heme (iron) group. In humans, most of our blood contains two alpha chains and two beta chains; however, elephant hemoglobin is slightly different. It is composed of 2 alpha globins chains and 2 fused delta-beta chains. It was assumed that Mammoths also had the same structure of hemoglobin; therefore, with that knowledge Dr. Campbell was able to construct tools necessary to fish out these chains from a 43,000 year old, well preserved mammoth. They discovered that the alpha chains differed from elephants in one of its amino acid units and the beta-delta chain differed in three units. This was all reported to Nature Genetics, because with this type of information, they could potentially reconstruct a mammoth hemoglobin.

The next step for Dr. Campbell and his team was to figure out a way to synthesize copies of the mammoth’s two globin genes. Dr. Campbell came up with a technique to just alter the DNA units of an elephant’s globin genes one by one at the four different sites until it matched that of the mammoth’s. This globin gene was then inserted into bacteria which was then synthesized into the mammoth globin chains. After inserting the required iron atoms, the globin chains were assembled into working hemoglobin molecules. This new development led Dr. Campbell to state, “It’s the same as if I went back 43,000 years in a time machine and took blood from a mammoth!”

This was a significant discovery in proving adaptive mutations for survival. As arteries carry blood down to the feet, they warm up the blood traveling up through the veins. Therefore, with this heat transfer, the blood at the toes are cold which prevents much heat loss. However, oxygen release from the hemoglobin becomes much less efficient at lower temperatures. With the construction discovery of the mammoth’s hemoglobin, scientists were able to determine how such an arctic mammal was capable of survival. The way the mammoth’s hemoglobin had evolved, it allowed for oxygen to be released from hemoglobin much more readily at lower temperatures.

Two years ago, scientists at Penn State University sequenced a large portion of the mammoth genome from a clump of well preserved hair. Now, with this completed reconstruction of their hemoglobin, scientists are getting closer to reconstructing the whole animal. Dr. Campbell states his optimism on the possibility; however, he also says “I’m 42 years old, but I doubt I’ll ever see a living mammoth.” We still have years of research left, but every step is one step closer!

Kevin L Campbell et. Al
Nature Genetics Volume: 42, Pages: 536–540 Year published: (2010)
DOI: doi:10.1038/ng.574 Received 18 December 2009 Accepted 31 March 2010
Published online 02 May 201

Link to article: http://www.nature.com/ng/journal/v42/n6/abs/ng.574.html#/