Saving California’s Big Bird

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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!

This week I had the unique opportunity to meet Conservation Program Manager Maggie Reinbold, who taught my fellow interns and I about the conservation efforts to help the California condor, and how scientists at the Beckman Center sex the birds using their chromosomes and DNA. With the efforts of conservationists at the Beckman Center, the condor population has risen from 22 birds in 1987 to more than 400 birds today, with almost 200 of them in the wild.

Mrs. Reinbold and intern Scott started off the experience by showing us the wingspan of the California condor, which is the largest bird in North America. Mrs. Reinbold explained to us that California condors are often confused with turkey vultures, but that the white inverted right triangles on the underside of the wings of condors are what differentiate them from the common turkey vulture. Condors are also substantially larger than vultures, and generally live in foothills, cliffs, and mountains.

Mrs. Reinbold showed us a tracking device used to track the recovery efforts of the condors released into the wild. Released California condors have struggled with lead poisoning, colliding with power lines, and feeding their babies “microtrash”, which looks like bone to a condor parent. However, by changing laws regarding hunting with lead bullets, training condors to avoid power lines, and by introducing condors to bone chips before entering the wild, the survival rates of released condors have gone up dramatically.

Intern Morgan (pictured here) is working on sexing a California condor based on its 14 macro chromosomes. Because condors are sexually monomorphic, (males and females physically look the same), scientists must use two techniques to sex the birds: either chromosome analysis, which Morgan is doing, or DNA analysis. Sexing these birds is essential for captive breeding programs.

This is the finished project of sexing a condor using chromosome analysis. After pairing up the 14 macro chromosomes with their partners, Mrs. Reinbold informed us that the sex of the bird can be determined by looking at the last chromosome pair. Male condors have perfectly matching sex chromosomes (ZZ), while females have a pair of sex chromosomes that do not match up perfectly (ZW). The chromosomes in this picture show that the condor I had was a male.

Mrs. Reinbold explained the second way to sex a condor, DNA analysis, using a reaction called polymerase chain reaction (PCR). PCR includes breaking open the DNA strand pictured here and making billions of copies of a certain part of the DNA you want to study called the target region; in this case, a gene on the sex chromosomes.

Intern Scott practiced the art of pipetting for the DNA analysis. Using special pipettes designed to accurately measure as little as two microliters, (a microliter is one millionth of a liter), we practiced drawing up food coloring before trying our hands at using pipettes with precious condor DNA and other reagents.

The tube pictured here contains the DNA of a California condor that I sexed using polymerase chain reaction. PCR includes breaking open DNA, attaching primers to the DNA, which attach to the target region, and adding polymerase, an enzyme that adds new base pairs throughout the target region. The steps of PCR are repeated until there are a billion copies of the target region.

Interns Keira and Hayden acted out the job of the polymerase enzyme in this picture by adding new base pairs throughout the target region. This crucial step in PCR makes the billions of copies of the target region necessary to determine the sex of the condor in question.

After my fellow interns and I completed our DNA analysis and polymerase chain reactions, we put our tubes containing the reactions in a machine called a thermocycler. The thermocycler makes the many temperature changes necessary to generate the billions of copies of the target region. Using the thermocycler, scientists at the Beckman Center can discover the sex of California condors and have a successful breeding program.

Thalia, Photo Journalist Team
Fall 2012, week two