A meia-vida do DNA em ossos: medindo a cinética de decaimento em 158 fósseis datados

segunda-feira, outubro 15, 2012

The half-life of DNA in bone: measuring decay kinetics in 158 dated fossils

Morten E. Allentoft1,2,3,*, Matthew Collins4, David Harker4, James Haile1, Charlotte L. Oskam1, Marie L. Hale2, Paula F. Campos3,5, Jose A. Samaniego3, M. Thomas P. Gilbert1,3, Eske Willerslev3, Guojie Zhang6, R. Paul Scofield7, Richard N. Holdaway2,8 and Michael Bunce1,*

Author Affiliations

1Ancient DNA Laboratory, School of Biological Sciences and Biotechnology, Murdoch University, 90 South Street, Perth, Western Australia 6150, Australia
2School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
3Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark
4Department of Archaeology, University of York, PO Box 373, York, UK
5Museu da Ciência, University of Coimbra, Laboratorio Chimico, Largo Marquês de Pombal, 3000-272 Coimbra, Portugal
6Beijing Genomics Institute-Shenzhen, Shenzhen 518083, People's Republic of China
7Canterbury Museum, Rolleston Avenue, Christchurch 8050, New Zealand
8Palaecol Research Ltd, 167 Springs Road, Hornby, Christchurch 8042, New Zealand

*Authors for correspondence
(morten.allentoft@gmail.com; m.bunce@murdoch.edu.au).


Claims of extreme survival of DNA have emphasized the need for reliable models of DNA degradation through time. By analysing mitochondrial DNA (mtDNA) from 158 radiocarbon-dated bones of the extinct New Zealand moa, we confirm empirically a long-hypothesized exponential decay relationship. The average DNA half-life within this geographically constrained fossil assemblage was estimated to be 521 years for a 242 bp mtDNA sequence, corresponding to a per nucleotide fragmentation rate (k) of 5.50 × 10–6 per year. With an effective burial temperature of 13.1°C, the rate is almost 400 times slower than predicted from published kinetic data of in vitro DNA depurination at pH 5. Although best described by an exponential model (R2 = 0.39), considerable sample-to-sample variance in DNA preservation could not be accounted for by geologic age. This variation likely derives from differences in taphonomy and bone diagenesis, which have confounded previous, less spatially constrained attempts to study DNA decay kinetics. Lastly, by calculating DNA fragmentation rates on Illumina HiSeq data, we show that nuclear DNA has degraded at least twice as fast as mtDNA. These results provide a baseline for predicting long-term DNA survival in bone.

DNA degradation aDNA decay kinetics DNA half-life

Received July 26, 2012.
Accepted September 14, 2012.
This journal is © 2012 The Royal Society




Será que depois desta pesquisa, os mandarins da Nomenklatura científica vão permitir pesquisas de DNA em ossos de dinossauros???

Pano rápido.