The Quality of MT-loop DNA Segment of Smokers and Nonsmokers in Lagos, Nigeria for Possible use in Forensic Biology

Abstract

Mitochondrial DNA (mtDNA) is a small circular DNA responsible for transmission of traits. In forensic biology, the high sensitivity of mtDNA analysis allows forensic scientists to obtain information from evidence associated with crime scene. This study was carried out to investigate the mtDNA segment of smokers and non-smokers and to determine to what extent smoking affects the quality of the mtDNA in the sample population. Twenty five cigarette butts were obtained from a bar and twenty five samples were also obtained from saliva of non-smokers using swab stick. Mitochondrial DNA (mtDNA) was extracted from individual samples using zymo kit, spectrophotometer was used to check for the concentration and purity of the extracted mtDNA. Polymerase chain reaction (PCR) was carried out in a gradient thermocycler to ascertain the hypervariable region of the mtDNA using the following primer sequence. Agarose gel electrophoresis was carried out to know the amplicon size using 100 base pair of ladder. The DNA purity on saliva extract for non-smokers was found to be higher (A260/280 2.06 - 1.82) than the purity of saliva from smokers (A260/280 1.82-1.0). The concentration of DNA found on the saliva traces from non-smokers was higher (26.2 - 3.0 ng/µl) than those extracts from smokers (26.2 - 2.23ng/µl). DNA bands obtained from agarose gel electrophoresis showed amplification of the hypervariable region of mtDNA size ranges from 295-300 base pair (bp). This study showed that the hypervariable region of the mtDNA of both smokers and non-smokers have the same range of nucleotide base pair (bp).