It has always been known that amber can
trap insects, plant parts, and other organic material. Scientists
have theorized for a long time that if insects can be so well
preserved in Amber, why not DNA as well?
One of the Major problems in getting
at the DNA is getting to the delicate insects containing that
DNA without damaging them, before need be and not contaminating
the sample with DNA from unconfined bacteria already living in
the lab.
One of the methods used to get at the
soft tissue of insects is the liquid nitrogen treatment method,
developed by Hendrik Poincar: (1) N2(l) is poured over
an insect bearing piece of Amber. Since Amber is a poor conductor
of heat, the outside portion of the Amber cools much quicker then
the inside portion, thus producing fracture planes throughout
the Amber. When an insect is entombed in Amber, it produces very
faint pressure planes within the Amber. These pressure
planes become fracture planes when the liquid nitrogen is poured
over the specimen. (2) Next, warm saline
is poured over the specimen and the resulting sharp, fast increase
in temperature causes the fracture planes to break apart. Sometimes
these fracture planes break right down through the insect, thus
exposing their soft tissue, (on their inside) containing the DNA.