Thursday, December 11, 2014

DNA in the Details



Fig.1. This parchment's DNA could hold clues to agricultural development three centuries ago. Document shows a sewn repair in Archbishop’s Register 7 Greenfield, 1306-1311.  (Credit: by permission of The Borthwick Institute for Archives)


Researchers may soon be looking into libraries and archives instead of natural history museums for ancient animal DNA. A recent study done at Trinity College Dublin and the University of York sought to trace agricultural development across the centuries through a DNA analysis of parchment documents. Instead of translating text, scientists extracted ancient DNA and protein from tiny samples of parchment from late 17th and 18th century documents. They were able to determine the type of animal from which the parchment was made, providing key information about agricultural expansion centuries ago.

DNA from parchment

Trinity College scientists extracted DNA from two small samples of parchments provided by the University of York’s Borthwick Institute for Archives. Protein samples were taken by researchers at the University of York and used to further identify the specimens. The first sample showed affinity with sheep breeds from northern Britain while the second sample was much closer to Midlands and southern Britain. Although this study was just a pilot project, this novel method yields new opportunities. Instead of analyzing fossilized bone fragments, the study utilizes a ubiquitous but surprising source of genetic material.

Before mass production of paper, parchment made from domestic animal skins was widely used. DNA extraction and analysis allows researchers to identify the animal and trace the agricultural history of that area. Although ancient DNA is notoriously difficult to study, due to DNA’s degradation over time and high probability of contamination, the parchment DNA was in remarkable condition. Parchment documents have been carefully managed throughout the centuries because they usually have important legal value. They are also often dated, a specificity not found with bone remains. These traits make parchment a compelling source for thorough DNA analysis.

 

A new scientific collection

Professor Daniel Bradley with Trinity College Dublin suggested that this study was just the start of something big.

“There must be millions [of parchments] stored away in libraries, archives, solicitors’ offices and even in our own attics,” he said in a statement. “After all, parchment was the writing material of choice for thousands of years, going back to the Dead Sea Scrolls.”

Book lovers and historians need not be worried about the destruction of important documents -- the amount of parchment necessary for testing is tiny. Though the impact is potentially quite large, this technique could provide insights into the breeding history of livestock throughout centuries of agricultural development.

The novel use of material preserved for a different purpose also transforms our understanding of scientific collections. Although not originally stored to track livestock movement, these parchment samples have a wealth of high quality information and are usually related to a specific date and location. In tandem with known demographic and cultural shifts, DNA analysis of parchment can be a window into our agricultural history.



References:

Teasdale, M.D., van Doorn, N.L., Fiddyment, S., Webb, C.C., O’Conner, T., Hofreiter, M., Collins, M.J. & Bradley, D.G. (2014, Dec 8). Paging through history: parchment as a reservoir of ancient DNA for next generation sequencing. Philosophical Transactions B, 370 (1660): DOI: 10.1098/rstb.2013.0379.

Trinity College Dublin. (2014) Scientists reveal parchment hidden stories [Press release]. Retrieved from http://www.eurekalert.org/pub_releases/2014-12/tcd-srp120514.php.



Glossary

ancient DNA
DNA isolated from ancient specimens, characteristically low quality DNA due to fragment length, base pair mutations, degradation etc.

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