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).
Highlights
Forensic identification is an effort to help law enforcement in determining a person’s identity
The purity absorbance range of sample 6 non-smoker group with the ratio of A260/280 was the highest with mean and standard deviation of 2.06 ng/ul ± 0.62 ng/ul, and the highest purity absorbance range of A260/280 ratio of DNA obtained from saliva traces on the cigarette butts were 1.87 ng/ul ± 0.42 ng/ul in sample number 1 of the smokers group
It was observed that the concentration level of DNA obtained from saliva traces on swab stick in sample no. 5 of non-smoker group was the highest with means and standard deviation of 52.64 ng/ul ± 10.31 ng/ul, and the highest concentration level of DNA obtained from saliva traces on the cigarette butts were 56.67 ng/ul ± 63.88 ng/ul for sample number 1 of the smokers group
Summary
Forensic identification is an effort to help law enforcement in determining a person’s identity. Personal identity is often a problem in criminal cases, civil cases, death without identity, and mass disasters[1]. Personal identification is defined as the act of establishing the identity of an individual. It arises in natural mass disasters like earth quakes, tsunamis, landslides, floods etc., and in manmade disasters such as terrorist attacks, bomb blasts, mass murders, and in cases when the body is highly decomposed or dismembered to deliberately conceal the identity of the individual[2]. There are several types of personal identification in forensic biology such as DNA analysis, Friction Ridge Analysis, Forensic Odontology, Biometric detection[3,4]. Deoxyribonucleic acid(DNA) analysis of evidential material is a powerful tool for linking an individual to a victim or a crime scene, DNA is a molecule that carries genetic material[5] which has been successfully extracted from many biological sources such as blood, semen, saliva, skin cells and used for different scientific analysis[6]
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