The Wildlife Professional - Spring 2010 2009

stick. Tiny bumps made the items appear rough, and Straughan hypothesized they were tastebuds of an unidentified mammal. This guess was a starting point for DNA analysis.

For mammals, Straughan typically amplifies the cytochrome b marker in the mitochondrial genome. For species identification, mitochondrial DNA is better than chromosomal DNA because there is

Credit: Jim Chamberlain/ USf WS forensics laboratory
forensic scientist Dyan Straughan focuses on pipetting, or transferring, Dna
from one tube to another as part of the lengthy process of identifying a species.

Credit: laurel a. neme
a bundle of dried laos warty newts signifies the toll of the illegal wildlife trade.
lor’s luggage contained 20 bundles of the recently discovered salamander
species, the largest known collection anywhere in the world. While some such
confiscated items are typically donated to museums, others—such as tongues—
may be destroyed to avoid the spread of hazardous toxins or disease.

more of it, it is maternally inherited, and it does not undergo genetic recombination. In addition, many markers, including cytochrome b, serve vital functions that ensure consistency across individuals of the same species.

With a razor blade Straughan sliced off a thin piece of the black “tongue” and dropped it into a small plastic test tube. To extract the DNA, she added a buffer and enzyme and agitated it overnight in a rotating oven. The next morning, she separated the DNA from the cloudy mixture and amplified it using the polymerase chain reaction to unzip and duplicate the DNA strands until she had billions of copies.

Once obtaining the sequences from the amplified DNA, Straughan compared them to those in the National Center for Biotechnology Information’s (NCBI) GenBank, an annotated collection of over 32 million publicly available DNA sequences. Failure to find a match could indicate either no records for a species, or use of an inappropriate marker, in which case Straughan would have to focus on a different section of DNA.

In this instance, however, the computer indicated a match: Capricornis sumatraensis or mainland serow—the largest of six species of goat-like antelope living in Southeast Asia, endangered in part because of heavy hunting due to its reputed value in curing bone diseases. To make sure her findings would hold up in court, Straughan verified her results with peer-reviewed sources and confirmed that lab items 12A and 12B were serow tongues stretched over wooden sticks. Another mystery solved—yet many more to go.

More Pieces of the Puzzle In another part of the lab, Barry Baker, the lab’s forensic herpetologist, gazed into a plastic evidence bag from the Lor case. Inside, more than 20 bunches of fragile, gnarly black twigs of what looked like beef jerky were tied together with twine. He pulled one out. Each of the feather-light six-inch “sticks” had a broad skull, four stiff legs with tiny unwebbed toes at the ends, and a long, rigid, laterally-compressed tail. There were five to a bundle and over 100 in all. Their musty fish smell, while not pleasant, was far less rancid than much of the other evidence that came through the lab.