DNA Extraction Made Easy

Written by: Paul Arnold • Edited by: Paul Arnold
Published May 20, 2009 • Related Guides: DNA | Nuclear Dna

A potential wealth of knowledge about the past is inside the DNA of ancient insects. Recovery of such genetic secrets has involved the partial destruction of rare specimens. This slowed down progress. New DNA extraction methods however can recover ancient DNA without destroying valuable samples.

Museums and institutions around the word house many fossilized insect specimens representing some 900,000 species at least. The amount of genetic diversity here is immense, and along with specimens found in permafrost sediments they can potentially reveal much about the insects and their phylogeny, ancient ecosystems and climate, as well as providing science with a tool to test evolutionary hypotheses.

DNA extraction procedures have primarily been focused on vertebrates and animals, and so a whole body of potential knowledge has been neglected. This is because DNA extraction from insects involves at least a partial destruction of morphological characteristics which is not ideal if you are working with rare specimens. However, all is not lost as there is a DNA extraction method that can recover ancient DNA without destroying valuable insect specimens.

DNA Extraction Procedure

For this non-destructive DNA extraction procedure whole specimens are immersed in a digestion buffer that contains amongst other chemicals, sodium dodecyl sulphate, dithiotreitol, and proteinase K and then incubated for 16-20 hours. Then the ancient insects are placed in 100% EtOH for 2-4 hours to stop further digestion, and then air-dried before being returned to their collections. The insect stays in good shape and the DNA is then extracted from the digestion buffer (Gilbert MTP et al. DNA extraction from dry museum beetles without conferring external morphological damage. PLoS ONE 2(3): e272. doi:10.1371/journal.pone.0000272).

Sufficient and viable quantities of mitochondrial DNA and nuclear DNA have been recovered, and then amplified by PCR.

So How is the DNA Liberated?

It is believed that (at least for the dry museum beetles that were used in the study) the ancient DNA escapes through various natural openings such as the spiracles, mouth, and anus.

This method holds much promise for extracting DNA without destroying specimens and in April 2009 its use was reported by the Centre for Ancient Genetics and Environments, Natural History Museum, University of Copenhagen. Scientists here employed this non-destructive DNA extraction technique on Siberian macrofossils up to 26,000 years old and museum beetle specimens that were up to 188 years old.

All of a sudden this new DNA extraction method is opening up a world of study to researchers.