Ichthyology

Thursday, February 18, 2016

KU Cryogenic Storage Expands with Biodiversity Collections

Andy Bentley removes specimens from a cryogenic dewar.

 

If you think you are cold this winter, remember others always have it worse. For instance, consider the tissue samples at the KU Biodiversity Institute.

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.

 

To put that in perspective, NASA satellites found locations in east Antarctica reaching temperatures of -135.8 degrees Celsius, or -93.2 degrees Fahrenheit, still almost 60 degrees shy of the dewar’s temperatures. These antarctic locations boast the lowest temperatures found naturally on earth to date. Humans are expected to survive only three minutes in these frozen conditions--not nearly enough time to build a snowman.
 
East Antarctica, warmer than a cryogenic dewar.
 
The extreme temperatures in dewars preserve usable DNA in tissue samples taken from whole specimens. The voucher specimens are often stored in structure-preserving formaldehyde solutions. However, formaldehyde destroys a specimen’s DNA, rendering them useless for further genetic study. Researchers need a way to keep both the DNA and the whole specimen preserved.

 

“We need a way to preserve DNA before the specimens are fixed in formaldehyde,” Bentley said. “So now in the field we take fresh specimens and extract samples of either internal organs or muscle tissue, place them in a tube, and freeze them before sending the rest of the specimen to be preserved.”

 

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.”

 

 


 

Friday, March 25, 2011

The Oarfish Omen

Oarfish

A week before the earthquake and tsunami hit Japan, an omen washed up on its beaches. The appearance of the oarfish, a ribbon-like, deep sea fish has long been perceived as a warning that seismic activity is on the way. This fish has become a feature of speculation as to whether they can be used to predict an incoming earthquake.

There are many news reports that speculate on the issue, as well as impressive photos of this critter, which can reach lengths in excess of 50 feet.

The important message here is that so little is known about the habits, breeding, biology, and ecology of these fishes – and deep water species in general. It is difficult to say what they are reacting to – small tremors signaling a larger quake to come, poisonous gases released by shifting tectonic plates or perhaps water temperatures affected by subtle movements in these plates. So little is known about deep water fish species due to the difficulty involved in studying them in their natural environment. They do not survive long (or act erratically/unusually) in shallow water, making it difficult to glean anything about their behavior based on these shallow water sightings. Their natural environment, depths below 1000 feet, is the place to study them, only possibly by using submersible or Remotely Operated Vehicles (ROV’s) but these tools are very expensive and not very numerous.

It is estimated that we have only described about a quarter to half of the species in the deep oceans. Who knows what lives down there and what sort of interactions they have with their deep water environment, as well as what sort of future events they may be able to sense before we know anything about them?

It is also interesting that local folklore (dismissed or ignored by many in the scientific community) says that these fish appearing in shallow water signal not only an earthquake, but also a good catch! These two are likely related in that tremors or earthquakes will scare or force deep water fish into the shallows.