Assessment of The Influence of Temperature on Brain DNA Quality for Forensic Studies Using Rapid Marker

Abstract

Forensic samples may need to be preserved for an extended period, therefore determining an
optimal temperature that allows for quality DNA to be obtained when required is essential. This
study seeks to ascertain the influence of temperature and postmortem time on the quality of brain
DNA for forensic studies. Seven (7) albino Sprague-Dawley mice weighing between 20 – 30
grams were used for this study. One (1) mouse which served as the control was sacrificed and the
brain tissue harvested for DNA extraction immediately. The remaining six (6) were divided into
two groups, where one group’s harvested brain tissues were stored at room temperature of 24 ℃
and the other group’s harvested brain tissues were preserved by freezing at -18 ℃ . DNA was
extracted from the brain tissues of one mouse each from the two groups after they had been
stored at the different temperatures for 24, 48 and 72 hours. DNA extraction was done using
DNA extraction kit from APS Life Tech West Africa Limited and PCR was carried out on each
of the DNA extracts using RAPD-OPC-04 primer. DNA concentration and # extracted DNA was
determined by spectrophotometry analysis, and the gel electrophoresis was also done to
determine the DNA band quality. The results from the spectrophotometry analysis showed that
there was consistent decrease in the DNA yield and purity from stored brain tissue samples as
compared to the freshly harvested brain sample. The gel electrophoresis showed consistent bands
for the DNA extract from the freshly harvested brain tissue and the brain tissue that was
preserved at -18 ℃ for 72 hours. Though, the best nuclear DNA quality is obtained from freshly
harvested brain tissues, the quality of nuclear DNA from brain tissue is better preserved by
freezing the brain tissue for long periods than at room temperature.