Abstract:
Analysis of ancient DNA (aDNA) gives archaeologists and anthropologists alternative and
innovative ways to interpret and understand the past. The postmortem instability of nucleic
acids, presence of inhibitory factors for analysis and the contamination with modern DNA
prevent authentic and high recovery of undamaged DNA from archeological specimens. Ancient
DNA is heavily modified over time, mainly due to spontaneous hydrolysis and oxidation and
consequently, most such specimens do not contain any Polymerase Chain Reaction (PCR)
amplifiable endogenous DNA while those that do amplify, generate only fragments in 100 – 500
base pairs in size. Nonetheless, the preservation rate of DNA in human remains is very low
under tropical conditions in Sri Lanka due to environmental conditions of high temperature and
high humidity.
The present study attempts to optimize a method of extracting and PCR amplification of DNA
from older human skeletal remains. Samples were obtained under strict measures to prevent
contamination with modern DNA. A 15year old (15YH) human humerus excavated from a burial
site at Kuliyapitiya and a 40year old (40YT) human tibia from the bone collection of Department
of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenapura, were analyzed.
DNA was extracted by a modified Phenol / chloroform method from each specimen and was
subjected to PCR using nested reactions in generating 4 overlapping fragments between the
nucleotide positions 15978 and 16417 of the human mitochondrial genome. The success of PCR
amplifications were verified upon agarose gel electrophoresis. At all the four reactions per each
bone generated DNA fragments of desired length (378bp, 247bp, 233bp and 233bp). The
products were purified and are being sequenced. The present study established methodologies for
extracting and analyzing of aDNA which has been exposed to climatic and environment
conditions that favor rapid DNA degradation. This optimized methodology is being applied for
mtDNA analysis of prehistoric human skeletal remains from Bellan bandi palassa, Fahien lena,
Sigiriya Pothana, Miniethiliya etc.
