February 1, 2008 Forensic scientists analyzing bones found in the Gobi desert discovered that the DNA within them could be surprisingly easily extracted. In an experiment designed to mimic the conditions that affected those bones, baking a particularly difficult sample made the DNA much more easily extracted, probably because it makes it easier to break open more cells and expose more of the DNA molecules.
- The Genographic Project
- Introduction to genetics
- Neandertal interaction with Cro-Magnons
Mummies have always held secrets, but now one of them has led to a new DNA technique.
Our fascination with mummies has sold millions at the box office. Now these preserved people -- mummies more than 800 years old -- are helping scientists reveal the mysteries of the past.
University of New Haven forensic scientist Dr. Heather Coyle is experimenting with a new technique by going back in time.
These are skeletal remains recently gathered from a Gobi desert cave. Surprisingly, Dr. Coyle was able to extract DNA from these mummies, but when she tried the same method on a body found in the USA, she was not as successful. "We realized that the bone we were trying to process was not yielding DNA from the case we were working on," Dr. Coyle said.
Standard DNA procedure for bones is to freeze them. When Coyle and her team re-examined the mummy remains they realized the Gobi desert created a natural bone baking process.
"It makes the bone more brittle so it makes it easier to grind and break open more cells, so we think we are accessing more DNA to begin with," Dr. Coyle said. Dr. Coyle decided to mimic nature by baking the cold case bones for 72 hours. Liquid nitrogen was then poured into a pulverizer. The bone was placed inside, ready to be crushed. After a short cycle the bone was turned to powder and ready for DNA extraction.
Coyle hopes her new technique will someday help close the book on several cold case files.
What is DNA? DNA is the blueprint that encodes all the data for building a human body, along with instructions on how it should operate. Every cell in a person's body contains a copy of this DNA.
DNA typing is based on an unusual feature found in the human genome. There are multiple copies of certain short sequences, 3 to 30 base pairs long, that are repeated one after another as many as 100 times. These groups of repeat sequences are widely scattered through the genome. Everyone has these repeat units, but the number varies from person to person.
Only identical twins will have the same numbers and patterns of these sequences. These genetic data aren't instructions to make anything; scientists think they might exist to get mixed up in the regular genes and provide some variety for evolution.