Totally [Test] Tubular!

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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 jobs, and then blog about their experience online. Follow their adventures here on the Zoo’s website!

shannon_W4_pic2The San Diego Zoo Global is famous for their success in breeding endangered and at risk species, specifically rhinos. This week we had the opportunity to meet one of the people who is part of one of the most successful breeding programs at the Zoo. Dr. Chris Tubbs, scientist at the Zoo’s Institute for Conservation Research, gave us a tour of his team’s lab and showed us how he works with southern white rhino reproduction.

Breeding animals isn’t as simple as placing a male and female together in the same enclosure, there is much more going on behind the scenes. Most of what happens to bring a new baby animal into the world begins in the lab with test tubes, samples, and hours of analysis. Dr. Tubbs and his team examine the hormones that are present in pregnancy and reproductive cycles. Hormones are chemical messengers that are released into the blood stream in order to trigger reactions. By testing and studying the hormones in the animals, Dr. Tubbs and his team can watch for changes in the amount of hormones which are associated with pregnancy.

Sampling and testing the animals for hormone levels is not that easy…do you know any 5,000lb rhinos that will happily cooperate with a large needle drawing their blood daily? Dr. Tubbs and his team have a more efficient way of doing things- though much more stinky. This is where the poop comes in! Weekly samples collected by the keepers are perfect for studying hormones from each animal. Dr. Tubbs explained that each waste sample is dried out, placed in a chemical solvent (like alcohol), and the hormones can then be extracted. The hormone levels are then charted to compare the levels of each hormone over time. For example, southern white rhino feces is sampled for levels of Progesterone which is a hormone produced by the female reproductive system. What Dr. Tubbs’s is looking for is high levels, or spikes, in the graph of progesterone to see if the rhino, or any other mammal, could be pregnant or ovulating (producing an egg). Similarly, when a human is pregnant or ovulating, there are higher levels of the HCG hormone that show up on a pregnancy test.

Recently, Dr. Tubbs had a new diet passed for the rhinos that could be very promising in the world of zoo-born animal reproduction. There has been a history of southern white rhinos raised in a zoo setting struggling with fertility and becoming pregnant. Dr. Tubbs explained that our environment and food intake has a large impact on our health and the same goes for animals. When looking into why the zoo-born rhinos were struggling with fertility, the team discovered that certain chemicals in the pellets that the animals are eating contain phytoestrogens. Phytoestrogens, found in soy and alfalfa, are chemicals that mimic the hormone estrogen which is linked with the female reproductive system. By mimicking estrogen, the animal’s body is tricked into thinking it doesn’t have to produce more estrogen and that greatly reduces their fertility. Dr. Tubbs’s team, working with the Zoo’s nutritionists, has produced a diet with less of these phytoestrogens in the hopes that the zoo-born southern white rhinos have a greater likelihood of producing offspring.

Hormones play a big role in the success of reproduction just like Dr. Tubbs plays a big role in aiding the Zoo’s rhino mothers. With the help of scientists like those in the reproductive physiology team, the San Diego Zoo can maintain its reputation of world renowned breeding facility. And, who knows, Dr. Tubbs and his team’s studies of hormones and diets could change zoo reproductive success for the better!

Shannon, Conservation Team
Week Four, Fall 2015

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