Largest Genome Ever Sequenced: 32 Billion Base Pairs!
© 2018 by Linda Moulton Howe
“We're just as excited as people were when they first decoded the human genome.”
- Elly Tanaka, Ph.D., Sr. Scientist, Research Institute
of Molecular Pathology, Vienna, Austria
Axolotl, a Mexican amphibian salamander, has the largest genome ever sequenced:
32 billion base pairs! That's 10 times the size of the human genome.
Image by Research Inst. of Molecular Pathology.
February 6, 2018 Albuquerque, New Mexico - Like a miracle creature, the axolotl amphibian salamander from Mexico is famous for “walking” on its cute arms and legs and being able to regrow those appendages if they get cut off, including bones, muscles and nerves. If the axolotl is wounded, it can heal without a scar. This amazing creature can even regenerate its own damaged internal organs. And if something crushes its spinal cord, the axolotl can restore its spinal cord to full function.
Most salamanders are able to regenerate body structures to some extent. But the axolotl is unique in that it can regenerate not only limbs, but also its jaws, spinal cord, and more. After these body parts regenerate, there is no evidence of scarring.
These remarkable resurrection abilities have made scientists wonder what its genetic code looks like and finally for the first time scientists used two genetic gene sequencing techniques to analyze and proof read their gene results. Axolotls can even receive transplanted organs from other individuals and accept them without rejection. They are one thousand times more resistant to cancer than mammals. Can scientist learn enough about the genetic makeup of the axolotls to apply their resurrection abilities to human medicine?
Axolotls (Ambystoma mexicanum) are salamanders that originate
from numerous lakes, such as Lake Xochimilco underlying Mexico City, Mexico.
Axolotls are unusual among amphibians in that they reach adulthood without
undergoing metamorphosis. Instead of developing lungs and taking to the
land, adults remain aquatic and gilled. Image © Branson's Wild World.
That's why this new work published in the current edition of the journal Nature (see Websites below) is considered a breakthrough for genome accuracy of such a long sequence of base pairs — 32 billion of them! That means the axolotl salamander has the largest genome ever sequenced, ten times the size of the human genome. The axolotl is also one of the few animals that exhibit neoteny, that is, it retains its juvenile characteristics, such as the external gills, which gives the creature its cute looks.
The senior author, Elly M. Tanaka, a senior scientist at the Research Institute of Molecular Pathology in Vienna, Austria. Dr. Tanaka is excited and says, “The adventure is just starting. Completing the genome will open up a wealth of opportunities in studying how organisms regenerate. We're just as excited as people were when they first decoded the human genome.”
Since axolotls absorb water and oxygen through their skin the kind of water that is used
in their homes is very important to their health. Many people may not realize that there is
a difference between distilled, bottled, tap and other kinds of water and if kept in
a human home, the axolotls should have bottled water that contain a good
balance of minerals and salts. Image © by John Gancalosi/Getty.