Scientists have discovered techniques to obtain DNA samples from specimens previously thought to be near-impossible to obtain genetic data by using pickled snakes taken decades ago and housed in an underground bunker of collections.
They utilized the DNA to answer a long-standing riddle concerning the family of an unusual snake from Borneo.
Collecting DNA from picked snakes
CARL DE SOUZA/AFP via Getty Images
The Field Museum in Chicago contains a subterranean bunker two stories beneath. The sub-basement Collections Resource Center stores millions of biological specimens for scientists all around the globe to utilize in their studies, including a library-like arrangement of bottles and jars containing pickled fish, lizards, and snakes, as per ScienceDaily.
Many of these specimens are decades or even centuries old and have been preserved nearly flawlessly by a mixture of formalin and alcohol.
However, the act of preserving tissues frequently destroys or makes collecting DNA for current research extremely difficult, which is terrible news for scientists studying genetic links between organisms.
As a true crime enthusiast, it reminds me of how, in the 1960s, no one could have imagined that one day DNA evidence would allow you to specify who committed crimes, says Sara Ruane, assistant curator of herpetology at the Field Museum and the study's senior author.
These older museum specimens are frequently the only examples of a species accessible, but they were not stored with DNA in mind; this study is about how we may extract as much information as possible from them.
The idea grew out of Justin Bernstein's dissertation study while he was a student at Rutgers University-Newark.
According to Bernstein, the paper's principal author, the major study is on a group of snakes known as homalopsids or mud snakes that reside in South and Southeast Asia, New Guinea, and Australia.
They're intriguing; they live in muddy, watery habitats, and there are 56 different species.
We use DNA to learn about their evolutionary history, to try to define new species, and to figure out what occurred to these groupings over tens of millions of years to produce the variety we see today.
For this work, Bernstein and Ruane were attempting to classify a two-foot-long greenish-brown snake known as Hydrablabes periops, also known as the olive small-eyed snake.
Such ancient specimens necessitated the use of modern laboratory procedures.
Typically, extracting DNA from a tissue sample entails adding digestive enzymes that break apart the tissue, leaving the DNA behind, and heating it to 130 °F for many hours.
They have to change the method we extracted the DNA by heating it hotter for longer periods and employing more of these digesting enzymes, explains Ruane, as per News Medical.
In prior investigations, these more severe preparation procedures were effective for other snakes, but the subsequent DNA analysis for Borneo's Hydrablabes snake specimen still had several gaps.
The chemicals employed to preserve the snakes sheared their DNA into shorter fragments of code, which made them challenging to compare with longer, more complete genes from other species, adds Bernstein.
The initial program that I used made it impossible to grasp how much-fragmented DNA there was across the research materials but moving to new software that showed the fragments of genetic code made it simpler to determine where there were difficulties.
And even the smaller, more fragmented chunks of code might be incorporated into bigger, public datasets to help form an evolutionary tree.
