Scientists Discover a Way to Sequence DNA of Rare Animals
01/24/2017

LSU Museum of Natural Science Curator Chris Austin developed and tested a protocol
to sequence the DNA of rare and even extinct animals from historic museum collections.Photo Credit: Eddy Perez, LSU.
BATON ROUGE – Rare and extinct animals are preserved in jars of alcohol in natural
history museum collections around the world, which provide a wealth of information
on the changing biodiversity of the planet. These preserved specimens of snakes, lizards,
frogs, fish and other animals can last up to 500 years when processed in a chemical
called formalin. While formalin helps preserve the specimen making it rigid and durable,
it poses a challenge to extracting and sequencing DNA. Furthermore, DNA degrades and
splits into small fragments over time. This fragmented DNA is difficult to amplify
into long informative stretches of DNA that can be used to examine evolutionary relationships
among species when using older DNA sequencing technology. Therefore, scientists have
not been able to effectively sequence DNA from these specimens until now.
LSU Museum of Natural Science Curator and Professor Christopher Austin and his collaborator
Rutgers-Newark Assistant Professor Sara Ruane developed a protocol and tested a method
for DNA sequencing thousands of genes from these intractable snake specimens. Their
research was published today in the international scientific journal Molecular Ecology
Resources.
“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. 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,” Austin said.
He and Ruane found and tested an approach that includes taking a small piece of liver
tissue from the snake specimen, heating it up over a longer period of time and applying
an enzyme that digests the tissue sample and enables the DNA to be extracted. Their
minimally invasive protocol preserves the specimen so additional information can be
collected from the specimen in the future. It also includes applying the latest technology
to chemically sequence the specimens’ DNA.
“A genome is a complex jigsaw puzzle broken up in to hundreds of millions of small
pieces. We can sequence those pieces and computationally put them back together,”
Austin said.
They extracted and sequenced the DNA of 13 historic or rare snake specimens from all
over the world many of which had never been analyzed using modern genetic methods.
Some of the specimens were more than 100 years old. They also integrated these data
with modern samples to create a genetic family tree, or phylogeny, that maps the evolutionary
relationships of various snake species. This work resulted in thousands of genetic
markers for snake specimens collected as far back as the early 1900s.
“The exciting thing about this work is that it makes species that have been essentially
lost to science, due to extirpation, rarity or general secretiveness, which applies
to many animals and not just snakes, available for scientific research in the modern
age of genomics,” Ruane said.
“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. It also underscores the continued importance of museum collections in
modern science,” Austin said.
This research was funded in part by the National Science Foundation (NSF DEB 1146033).
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Additional Link:
Phylogenomics using formalin-fixed and 100+ year old intractable natural history
specimens, Molecular Ecology Resources:
http://onlinelibrary.wiley.com/doi/10.1111/1755-0998.12655/pdf
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Contact Alison Satake
LSU Media Relations
225-578-3870
asatake@lsu.edu