Established in 2006, the Florida Museum of Natural History’s Genetic Resources Repository archives tens of thousands of tissue samples and DNA and RNA preparations from physical specimens in the Museum.
How are genetic specimens collected and stored? Read on to find out!
Liquid Nitrogen Freezer
The central component of the Florida Museum of Natural History’s Genetics Resource Repository is a liquid nitrogen freezer (model MVE 1830HE), located in Dickinson Hall on the University of Florida campus. It is designed to maintain temperatures below minus 300 degrees Fahrenheit. The freezer can store nearly 80,000 samples in 2-ml plastic vials.
The freezer is equipped with 54 racks arranged in six sections. Each rack holds 13 boxes of 100 vials. When the current configuration reaches capacity, the Museum plans to add 30 racks (designed to hold 25-cell boxes) to reach the freezer’s largest capacity configuration. During regular operation, employees wear leather gloves and a protective face mask to minimize risks associated with handling liquid nitrogen and materials at cryogenic temperatures.
A small computer attached to the freezer uses a pressure sensor and two temperature probes to maintain the nitrogen level at a minimum of 5 inches. When the level drops below this setting, the computer opens a valve connecting the freezer to a liquid nitrogen tank. If liquid fails to flow from the tank, an alarm is triggered.
The freezer can hold 1,672 liters of nitrogen, but only requires 296 liters for the vapor level to maintain low temperatures. This volume keeps all storage racks above the liquid nitrogen. The rate of nitrogen consumption varies depending on how often the freezer is accessed. To reduce nitrogen use, the Museum processes loans and new accessions one day a week. At this access rate, the 180-liter tank must be replenished every eight to nine days.
Plant Collecting: Field & Lab Work
The University of Florida Herbarium of the Florida Museum of Natural History and the Laboratory of Molecular Systematics and Evolutionary Genetics conduct an array of projects with many plant groups.
The Genetics Resource Repository stores plant material researchers obtain during collecting trips.
The Repository stores DNA samples obtained from herbarium sheets or tissues that have been dried and stored in silica gel. Samples of DNA are used in phylogenetic and population studies, with the remaining DNA stored in the Repository. The Museum tries to store at least 50 microliters of DNA per sample, and documents the concentration and collection information, including location, date and collector.
Mammals Tissue Preparation
The mammal collection receives a wide variety of samples that range from small rodents to whales. The Florida Museum acts as a State Repository for wildlife. Each specimen that is received is processed, and the skin, skeleton and tissues are prepared. In this process, additional biological information is obtained.
A large number of specimens deposited in the GRR by the Mammal range are endangered Florida Panthers (Puma concolor coryi) that are run over by cars or die in fights with conspecifics for territory due to the loss of their habitat. The tissues that we preserve are silent witnesses to the fate of this species, emphasizing the need for a better understanding of this species to guide conservation efforts.
Ms. Candace McCaffery, Collections Manager of the Mammal range, and students collect biological data for the specimen and prepare tissue samples of a male Florida Panther approximately one and a half years old that was run over by a car. This specimen was deposited in the Museum by the Florida Game Commission Office.
Fishes Tissue Preparation
The Florida Museum of Natural History Fish Collection contains approximately 2,225,000 specimens. Included are representatives of 8,250 species (29% of an estimated 28,000 worldwide) from 400 families (78% of total). The Fish Collection is growing at an annual rate of 4% or about 78,000 specimens. The rapid growth is the result of receiving many specimens from surveys and other scientific studies centered in the Atlantic Ocean and Gulf of Mexico, as well as from research programs at UF, including the NSF-funded “PBI: All Catfish Species Inventory” and several research projects on sharks and rays. Additional growth has resulted from acquisition of orphaned collections, including from those of the University of Miami, University of West Florida, Florida Atlantic University, and Harbor Branch Oceanographic Institute. In 2006, the Museum expanded its program to archive frozen tissue samples with the newly established UF-FLMNH Genetic Resources Collection.
A recent example of the use of genetic resources is the study of the Florida Bass (Micropterus floridanus). Historically considered a subspecies of the Largemouth Bass, the Florida Bass, according to recent studies, should now be recognized as a distinct species. The Florida Bass is an extremely popular sport fish, and policies related to stocking and environmental issues are affected by its taxonomy. Museum scientists are using tissue samples from throughout eastern North America to look for evidence of intergradation between the Florida Bass and the Largemouth Bass and, from those data, determine the correct taxonomy.
Museum scientists are using tissue samples from throughout eastern North America to look for evidence of intergradation between the Florida Bass and the Largemouth Bass and, from those data, determine the taxonomy.
Birds Tissue Preparation
The Ornithology range collects and receives bird specimens and stores them in a -20 C freezer until they can be processed and integrated in the GRR.
The preparation of specimens consists of obtaining the skin, the skeleton, and the tissues. In this process, additional biological data for the specimen (e.g., approximate age) are obtained and integrated in the database. Normally two sets of tissue samples are prepared from the liver, heart, and muscle; occasionally these samples are preserved in saline solution, but normally no buffer or preservative are used. One tissue sample remains in the GRR at Florida Museum, and the second one is sent to the tissue collection of LSU.
The tissue collection grows by approximately 20 bird specimens per week.