Andy Bentley removes specimens from a cryogenic dewar.
The KU Biodiversity Institute stores thousands of tissue samples from species found around the globe at a frosty -175 degrees Celsius. The specimens are stored in dewars, which are large, vacuum-sealed containers with a pool of liquid nitrogen at the bottom. While -175 degrees is hard to imagine, the newest dewar at KU dips even lower.
“The latest one we’ve acquired runs at -190 degrees Celsius, but otherwise functions much in the same way,” said KU Ichthyology Collections Manager Andy Bentley.
East Antarctica, warmer than a cryogenic dewar.
Tissues preserved in the dewars are in constant demand. Researchers from all over the world review online catalogs of stored specimens and send requests for tissues that could further their research. Upon receiving a request, the specimen is carefully extracted from the dewar and thawed on ice. Once thawed, a tiny piece of tissue is sliced from the sample and shipped in ninety-five percent ethanol.
The number and variety of specimens available for research is growing rapidly. The two dewars currently used are quickly filling with tissue samples. Bentley expects the newest dewar to see use before 2017.
“There’s new material coming in from the field at a rate of ten percent a year,” Bentley said. “In ichthyology we expect another 1,100 tissues a year, so with that kind of growth across all departments we expect to fill the two current dewars in six to eight months.”
When the first two dewars near capacity, the third will be filled with eight-to-ten inches of liquid nitrogen. This level is monitored 24 hours a day to maintain the crucially cold temperatures. Once filled, the third dewar stands ready to support the growing collection.
“There is a fairly large portion of material that is unique to our collection,” Bentley said. “The ichthyology collection, we think, is probably one of the largest ichthyology tissue collections in the world, based on taxonomic and geographic scope.”