In Thailand, it is illegal to trade ivory from African elephants; however, the law allows possession of ivory from Asian elephants if permission is obtained from authorities. Of course, poachers try to get around this by shipping ivory stolen from African elephants to Asia and then quickly breaking it down to tiny pieces for jewelry or other trinkets. The miniscule amount of DNA contained in elephant husks already makes detection difficult—add in analysis of small pieces and the task becomes monumental.
But that didn’t stop a team of international researchers from developing a new test to give customs agents a leg up. Researchers at Flinders University (Australia) and colleagues in Thailand—all part of a team focused on developing forensic DNA technology to thwart the global black market on exotic animals—have developed an in-field, rapid, inexpensive technique to identify trace amounts of ivory for degraded samples as small as 0.003 ng.
The new denaturing gradient gel electrophoresis method is simple, inexpensive and does not require special equipment, which sets it apart from other methods. In the past, DNA sequencing has been a common detection method, but that obviously requires access to a DNA sequencer. SNP testing is also used but this technique requires fluorescence detection equipment. Contrastingly, the researchers’ gel electrophoresis method can be performed utilizing standard laboratory equipment.
In their paper, published in the International Journal of Legal Medicine, the scientists used their gel electrophoresis method to test DNA from aged ivory for reproducibility and specificity. Blind testing of 304 samples resulted in 100% identification accuracy.
But most importantly, the test provided highly sensitive—results showed correct assignment in the legal status of 227 highly degraded, aged ivories within the test cohort. Since species who share a recent common ancestor, like African and Asian elephants, have little variation in their DNA, detecting the difference between the two species at a genetic level is complex.
“The variation in the DNA can be single base changes,” Adrian Linacre, forensic science chair at Flinders University and co-author of the paper, told Forensic. “But this test works off trace material and only requires a section of the mitochondrial genome 70 bases in length since it is highly sensitive. Results were routinely and reliably obtained from 0.003 ng, even on trace and aged samples.”
Another benefit of the new method is that it can be performed in-field.
“Wildlife testing is often performed away from fully accredited laboratories,” said Linacre. “Mobile, rapid in-field testing is a goal for many areas of forensic genetics. What this test does is add yet another tool for wildlife scientists who are faced with a multitude of trace material that looks like ivory but might not be.”
The scientists say they still have more research to do. Since the test was designed in Thailand, where trading Asian ivory is legal, but trading Africa ivory is illegal, this specific test cannot discriminate between two African elephant species. Even so, Linacre says the new test will have international implications for the illegal trafficking and poaching of ivory.