A Frozen Zoo

Zoo InternQuest is a seven-week career exploration program for San Diego County high school juniors and seniors. Students have the unique opportunity to meet professionals working for the San Diego Zoo, Safari Park, and Institute for Conservation Research, learn about their jobs and then blog about their experience online. Follow their adventures here on the Zoo’s website!

carly_W3_picThe San Diego Zoo Institute for Conservation Research (ICR) houses the largest Reproductive Physiology lab in the United States. Dr. Barbara Durrant, Director of the Reproductive Physiology Division, and Senior Research Technicians, Ms. Carly Young and Ms. Nicole Ravida, preserve animal cells and DNA for the future.

Did you know cat sperm is a close match to bear sperm? The Reproductive Physiology Lab has teamed up with the Feral Cat Coalition (which captures and spays/neuters feral cats) to obtain feline sperm that would otherwise be thrown away. They use this supply of sperm to test and perfect their methods in the lab, including new techniques for freezing and thawing these animal reproductive cells. Researchers want to know the best way to freeze the cell samples so that they may produce more motile sperm when thawed; motile sperm are more likely to reach and fertilize the egg. However, one technique does not work for all types of sperm, thus, multiple techniques must be tested on multiple samples to determine the best methods for different species of mammals, birds, and even reptiles.

Sperm samples are not the only cells researchers preserve. Located on the floor of the Beckman Center at the ICR, the Frozen Zoo® houses thousands of gametes (reproductive cells including eggs and sperm), cell cultures, embryos, blood, and DNA of different species of animals. These samples have been collected over the past thirty-seven years, and will continue to be collected, preserved and thawed when necessary. This process has become a priceless tool for conservation efforts nationwide.

So when would these cells be needed? There are many techniques used in the general field of reproductive physiology, such as invitro fertilization, artificial insemination, and a relatively new process called ICSI, or intracytoplasmic sperm injection. For instance, if a natural disaster swept out an entire species of animal but their gametes were kept at the Frozen Zoo®, reproductive physiologists could possibly implant the species’ sex cells in a related animal and produce a baby. The new process, ICSI, is groundbreaking in that a single sperm cell is injected into a single egg, rather than placing hundreds of sperm inside the oviducts (as in artificial insemination). Amazingly, the sperm cell does not have to be motile, as it does not have to travel through the reproductive system to fertilize the egg—it is already inside. Reproductive physiologists have also realized that the sperm’s tail must be crushed when placed inside the egg, as the tail then releases enzymes from its membrane which help the zygote (fertilized egg) split into two. ICSI is used for extremely precious animals to bring them back from the brink of extinction.

There are a limited number of reproductive physiology labs working on these techniques in the United States. As more people spread the word about work done with the Frozen Zoo®, this branch of conservation will receive more support and attention. Awareness is key to ensuring the survival of these labs and the species they work to protect.

Carly Jo, Conservation Team
Week Two, Winter Session 2013

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