Genetics > What's This? Frozen Tissue

The black part is the skin surface and the orange part is blubber. If you look closely, you'll see that this tissue sample is very smooth and shaped like a dart. Scientists collected it using a hollow-tip dart shot from a crossbow. The dart hits the whale and bounces off with a tissue sample within its tip. That may sound painful, but it doesn't hurt the humpback whale a bit.

Imagine having the genetics  data of thousands of animals all in one room!

Take a peek inside the Museum's Frozen Tissue Collection with collection manager Julie Feinstein . She is standing next to one of seven cryovats, stainless-steel cauldrons filled with liquid nitrogen. These giant freezers are kept at a frosty -160°C (-256°F). That's eight times colder than home freezers!

Inside you'll find tiny plastic vials that contain animal tissues collected by scientists. They are preserved for a really long time so that scientists can study the animals' DNA  now and in the future.

A clip of a bat's wing, a strand of lemur hair, or a piece of turtle shell — just a tiny part of an animal's tissue is all scientists need to study its DNA.

You're looking at a tissue sample of the frilled leaf-tailed gecko (Uroplatus fimbriatus). These geckos are the largest living geckos in the world. They live only in the rainforests of Madagascar . Scientists are studying its DNA to understand how this species is related to other smaller geckos.

How many insects can you see inside this vial? If an animal is small enough, many whole specimens can be stored together.

The Frozen Tissue Collection has about 500 vials of fruit flies (Drosophila species). Each vial contains about 25 specimens — for a total of about 12,500 flies. Scientists at the Museum are using these fruit flies to analyze a type of bacterial infection that affects many insects, including butterflies and scorpions. They also want to understand how different kinds of fruit flies are related to each other.

Did you know that animal dung is a good source of DNA? As a mammal digests its food, cells  are scraped from its intestinal walls and become part of the waste.

But scientists need to be careful when analyzing the genetic information found in dung. For example, this coyote dropping contains not only the DNA of its owner, but also the DNA of its owner's meal, like a mouse or a bird. Scientists who are familiar with the coyote's genome  will be able to make copies of just the coyote DNA.

This may look like a drop of water , but it's actually scorpion DNA suspended in liquid. The DNA has been extracted, or separated, from the scorpion tissue. How do scientists extract DNA? First, they take a tiny piece of tissue (about the size of a grain of rice) and mix it with a special liquid chemical. This helps breaks down the cell membranes and releases the DNA from the nucleus . Then they pour the mixture into a high-tech device that separates the DNA from everything else. Finally, the scientists collect the DNA in a small test tube.