About Author: Jennifer Burchell

Posts by Jennifer Burchell


Makeshift Lab in Ecuador Helps Frogs

DNA extraction in HotelA few months ago I got the incredible opportunity to help bring the Amphibian Disease Laboratory’s molecular diagnostic capabilities abroad. Our amphibian disease laboratory head, veterinary pathologist Allan Pessier and I, along with several other veterinarians and conservation biologists, were invited to speak at an International Veterinary Medicine of Amphibians seminar in Quito, Ecuador. It was amazing to be able to share our lab’s diagnostic techniques with eager veterinary students and biologists.

While packing for our trip abroad, I thought of everything we would need to have our “mobile lab” functional. Even though I had all the equipment and re-agents we needed, I could not prepare for the location where I would perform these experiments.

When we arrived at the seminar location, I was relieved to see that the area where we would be performing our amphibian disease testings at was a veterinary clinical lab. Here we had counter space, power outlets, and refrigerator space. However, the molecular testings take time to run (about 2.5 hours), and the real-time PCR machine I was utilizing could only manage 48 samples at once. I ran into time limitations of how long we had to be in the facility. We needed to make sure we ran all the samples given to us by the animal facilities before we went back to the US. I had to improvise and wound up turning my hotel room into a makeshift laboratory. I had an extraction area (bedside table), my re-agent master mix preparation area (the dressing table), and my DNA loading area and instrument area (another bedside table). But do I use to keep my re-agents cool? Why, a foam cooler and ice cubes purchased from a nearby market! I extracted my samples, set up the assay instrument, and went to sleep with the humming of the real-time instrument next to my bed.

What did I learn from this amazing experience? That you can only prepare so much when traveling abroad and that you need to be ready to think on your toes and be prepared to do your experiments in not-so-ideal environments.

The outcome of the trip was most rewarding. Our hours of traveling allowed these students and biologists to utilize techniques that aren’t easily available to their institutions. The testing results were very helpful not only to the animal facilities themselves but also to our laboratory to understand the amphibian disease present in Ecuador. These are the types of relationships we would like to have with amphibian facilities across the world to help monitor the health of current and future amphibian populations.

Jennifer Burchell is a research coordinator at the San Diego Zoo Institute for Conservation Research. Read her previous post, Counting Mosquitoes.


Counting Mosquitoes

Summer interns Kathleen Connolly, left, and Christina Mangan pose with some of their finds.

Since October 2011, we have been monitoring disease vectors in the Safari Park Biodiversity Preserve (aka The Back 900). Here, the valuable coastal sage scrub habitat has been undergoing cactus restoration as well as monitoring of one of its important inhabitants, the cactus wren (see post Cactus Wrens Rise from the Ashes). Our goals are to monitor the presence and activity of mosquitoes and midges, two important disease vectors, and test them for West Nile virus and blood parasites, including plasmodium, the cause of avian malaria, in and around this reserve. From this data, we will be able to look at the occurrence of these disease agents in insects within the cactus wren habitat and which mosquito or midge species act as likely vectors.

Another interesting aspect of this study is analyzing what hosts these insects have been feeding on by evaluating their blood meals. Only females feed on blood; the male mosquitoes and midges feed on nectar. So for this study we are only concerned with the female insects. DNA is extracted from the blood meal, and a barcoding PCR is performed. The PCR product sequences are then compared to published sequences in the Barcode of Life database, which contains DNA sequence information for a large number of animals. Finding a match between the DNA sequence extracted from the blood meal and a known DNA sequence will enable us to determine which animals these insects have been feeding on. Mosquitoes and midges within the Safari Park have been found to feed upon various local creatures, including mallards, desert cottontail rabbits, mule deer, humans, and an occasional collection animal.

So, how do we convince the insects to be tested? Once every other week, our summer interns and I go out into the field, setting up UV traps and CO2 traps to attract and capture mosquitoes and midges. While out in the field, it can be quite an adventure, from the bumpy roads and rolling hills to the occasional visit from a resident mule deer or a speeding roadrunner. It is often enjoyable to get out of the laboratory and into the field and observe virtually undisturbed habitat right in our own Park’s backyard.

The UV traps attract the mosquitoes by emitting a UV light of about 350 to 400 nanometers; this acts as a visual stimuli for the mosquitoes and midges. The CO2 trap contains dry ice that emits CO2 to mimic the respiration of an animal and works as a chemical attractant for the insects. After anesthetizing the insects back at our Wildlife Diseases Laboratory, the students then have the arduous task of tediously counting and identifying the various species of mosquitoes and midges. Later, they extract the DNA and RNA from these insects and utilize it for the PCR testings.

This project has given our interns the opportunity to gain experience in the laboratory and in the field!

Jennifer Burchell is a research coordinator for the San Diego Zoo Institute for Conservation Research. Read her previous post, Invisible Clues.


Invisible Clues

An ashy-headed goose

Working in the Molecular Diagnostic Laboratory is often an adventure. I never know when I am going to get an email or phone call from our Pathology Lab letting me know we have an interesting animal case and they are sending a liver, or a lung, or various other animal parts for testing using our molecular techniques.

When the clinicians and pathologists have a good idea of what disease or pathogen the animal may have, our molecular diagnostic tools can be just the thing they need to confirm and back up their diagnosis. In some unusual instances, our testing may even reveal a pathogen that has never been described in that particular species. One method we use most often is PCR (polymerase chain reaction). With this tool we can use extracted DNA or RNA from the animal sample and amplify it from a few copies to millions of copies. In order to make this technique very sensitive and specific, we use primers that are specifically designed to attach to and amplify certain targeted genes of viruses, or other pathogens.

One interesting case example was a 15-year-old female ashy-headed goose that had died. A thorough review of her health history, as well as a necropsy and histology, was performed. The clinicians and pathologists had an idea as to what organism could be affecting this animal but needed further confirmation so that the lagoon exhibit could be managed in the most appropriate and effective manner. After extracting the DNA from the goose’s cecum and liver, running it on a conventional PCR, cloning (inserting the PCR product into a vector) it, and finally sequencing the PCR products, the clinicians’ and pathologists’ findings in conjunction with the molecular results determined that Avian schistosomiasis, an infestation of trematodes (blood flukes, scientific name Dendritobilharzia pulverulenta) was what made this bird sick.

Having these valuable techniques available is a complement to the management processes that protects and maintains the health of San Diego Zoo Global’s animal collections. Working with such a talented team of clinicians, pathologists, and all the animal care staff is very rewarding and fulfilling!

Jennifer Burchell is a research coordinator for the San Diego Zoo Institute for Conservation Research.