Scientists can start extracting DNA from the rare, often extinct, animal specimens collected over the centuries and preserved in jars of liquid at natural history museums around the world under a new system developed at LSU and Rutgers.
“It’s not quite Jurassic Park, but we can get genetic data from extinct species and we can determine where those species fit on the ‘tree of life’,” said Professor Christopher Austin, referring to the popular book and movie about finding ancient genetic material, then recreating dinosaurs by sequencing long fragments of the hereditary material and instructions for growth found in the double helix of deoxyribonucleic acid, or DNA, in each cell.
“We don’t have dinosaurs preserved in formalin and alcohol. But if we did, we could,” said Austin, who also is curator of the LSU Museum of Natural Science.
More realistic than the fictional dino park is that scientists can use the old DNA to track how species evolved and how they are related to other species.
Austin and Rutgers University-Newark Assistant Professor Sara Ruane developed a protocol for sequencing thousands of genes from snake specimens, some more than 100 years old. Their research was accepted for publication last week in Molecular Ecology Resources, an international scientific journal. The research was funded, in part, by the National Science Foundation.
For generations, scientists have gathered specimens and preserved them in a chemical, called formalin, and alcohol. Formalin helps preserve the specimen, making it rigid and durable. The technique can preserve snakes, lizards, frogs, fish and other animals for up to 500 years.
But the liquids make it difficult to extract and sequence DNA. It causes the genetic material to split into small fragments, making it difficult to reconstruct long enough strands for useful genetic study.
“A genome is a complex jigsaw puzzle broken up in to hundreds of millions of small pieces. We can sequence those pieces, and using a computer, put them back together,” Austin said. As recently as 10 years ago that seemed impossible.
“What we did was come up with novel extraction methods,” Austin said.
Austin and Ruane found an approach that includes taking a small piece of liver tissue from a snake specimen – Austin specializes in reptiles and amphibians – heating it up over a longer period of time and applying an enzyme that digests the tissue sample. This enables the DNA to be extracted.
They applied the technique on a rare Xylophis stenorhynchus, commonly called Gunter’s Mountain snake that had been collected between 1878 and 1911 from near Travancore in the Western Ghats mountain range of southwest India. The LSU specimen is one the few available anywhere.
The DNA extracted indicated that the burrowing mountain snake that feeds on earthworms is more closely related to another species that favors snails than with other burrowing snakes, as previously thought, according to the article.
They successfully sequenced about 3,433 gene regions from 10 snakes, including from specimens collected more than a century ago.
“Natural history museums are repositories for extinct species. Unfortunately, naturalists in the 1800s were not collecting specimens for analyses we conduct today such as DNA sequencing,” Austin said. “Now with these new methods, we can get the DNA from these very old specimens and sequence extinct species like the Ivory Billed Woodpecker, the Tasmanian Wolf and the Dodo Bird.”
Beyond the ivory tower of scholarship, better understanding of how a snake evolved and where the species in relation to other snakes, helps scientists better understand how to use venom, which often goes into medicines that treat high blood pressure, diabetes, and other maladies.
And as Louisiana’s coastline is changing, charting the frogs and lizards that once lived in the marshes, but no longer do, can help scientists get a better handle on the conditions leading to coastal land loss.
“We also believe this research will benefit scientists working with rare animals that are either hard to collect or extinct but are represented in fluid-preserved historical collections,” Austin said. “It also underscores the continued importance of museum collections in modern science.”