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Abstract

Blow flies are the primary colonizers of human cadavers. In many death investigations, insect evidence can help in prediction of minimum post-mortem interval (PMImin) but to do that, the first step is to identify collected insect evidence. For immature stages, morphological keys are either limited or incomplete and hence DNA based identification is used. For DNA based ID, DNA extraction is the first and the most important step, especially when collected evidence is highly degraded. The main aim of this study was to compare three DNA extraction methods (QIAgen Blood and Tissue Kit, organic, and QIAgen DNA Investigator Kit) to determine the quantity of recovered DNA from 45-year-old pupal cases. To accomplish this goal, each pupal case (n=10 for QIAgen Blood and Tissue Kit, n=5 for organic extraction, and n=5 for QIAgen DNA Investigator Kit) was used as a sample for DNA extraction for each method. Extracted DNA was quantified using the Qubit fluorometer. Extracted DNA (only from QIAgen Blood and Tissue Kit and organic method) was then amplified for mitochondrial cytochrome oxidase one (COI) gene and amplification success was visualized using agarose gel electrophoresis. Mitochondrial COI gene amplification didn’t result in a PCR product from any sample. Results from this study indicated that the QIAgen Blood and Tissue Kit is a significantly better DNA extraction method than the QIAgen DNA Investigator Kit for highly degraded pupal cases, as this method yielded more insect genomic DNA. However, there was no significant difference between the QIAgen Blood and Tissue Kit and organic method, or the organic method and the QIAgen DNA Investigator Kit.

Publication Date

2024

Subject Major(s)

Biology

Keywords

Forensic Science, DNA based insect identification, Cold Case, Degraded Sample, Blow Fly

Disciplines

Cell Biology | Entomology | Genetics

Current Academic Year

Junior

Faculty Advisor/Mentor

Dr. Baneshwar Singh

Rights

© The Author(s)

A Comparison of Three DNA Extraction Methods on 45-year-old Pupae Cases

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