Tuesday, April 2, 2013

Meeting red wolf recovery criteria: Cryogenic preservation of red wolf sperm

Did you know that the current red wolf recovery plan has four recovery objectives? We often focus on establishing populations and avoiding extinction, but another recovery objective is to maintain the red wolf into perpetuity through embryo banking and cryogenic preservation of sperm. This work is coordinated through by the Red Wolf Species Survival Plan (SSP) through the Association of Zoos and Aquariums. The majority of this research occurs at Point Defiance Zoo and Aquarium under the guidance of the Red Wolf SSP Reproductive Advisor and SSP Coordinator.

Red wolf sperm under the microscope. Photo credit: Toronto Zoo.

Using technologies to support red wolf conservation and population sustainability relies on the help and expertise of many individuals and organizations. One such technology that the Red Wolf SSP began using in 1990 is the freezing of sperm collected from red wolves managed in the captive population. Initially developed within the livestock industry, the process involved in semen collection and freezing has been refined and improved over the years and is now used for a variety of species including those that may be threatened or endangered. In fact, many dog owners will “bank” samples to preserve, for example, sperm from valuable show or hunting dogs. These samples can potentially be used for artificial insemination to produce offspring once an animal is beyond its breeding age or has passed away. The International Canine Semen Bank (ICSB), located in Oregon, stores samples for the Red Wolf SSP and has produced dog litters from frozen semen that had been stored for 38 years prior to thawing and insemination.

Collected samples are analyzed under the microscope to exam sperm motility, concentration, and the percentage of normal shaped sperm. If these samples are sufficiently vigorous, the process for freezing begins. This basically involves combining the samples with an extender or cyroprotectant to safeguard the cells against damage during freezing followed by a slow cooling phase for 30 minutes. The samples are then carefully pipetted on to a block of dry ice with small indentations to form pellets and left to sit for 3 minutes. Finally, the pellets are plunged into liquid nitrogen, placed in small vials, and sent to ICSB for storage in liquid nitrogen tanks. 

Samples being "pelleted" onto dry ice.
Photo credit: Jesse Michener/Point Defiance Zoo & Aquarium. 

Karen Goodrowe-Beck, Red Wolf SSP Reproductive Advisor, 
processing samples for examination.
Photo credit: Jesse Michener/Point Defiance Zoo & Aquarium.
While this is kind of approach is not meant to replace red wolves breeding naturally, it is a valuable tool that we can use to manage the red wolf population into the future.

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