Application of DNA Fingerprinting using the D1S80 Locus in Lab Classes

Abstract

In biological sciences, DNA fingerprinting has been widely used for paternity testing, forensic applications and phylogenetic studies. Here, we describe a reliable and robust method for genotyping individuals by Variable Number of Tandem Repeat (VNTR) analysis in the context of undergraduate laboratory classes. The human D1S80 VNTR locus is used in this protocol as a highly polymorphic marker based on variation in the number of repetitive sequences. This simple protocol conveys useful information for teachers and the implementation of DNA fingerprinting in practical laboratory classes. In the presented laboratory exercise, DNA extraction followed by PCR amplification is used to determine genetic variation at the D1S80 VNTR locus. Differences in the fragment size of PCR products are visualized by agarose gel electrophoresis. The fragment sizes and repeat numbers are calculated based on a linear regression of the size and migration distance of a DNA size standard. Following this guide, students should be able to: • Harvest and extract DNA from buccal mucosa epithelial cells • Perform a PCR experiment and understand the function of various reaction components • Analyze the amplicons by agarose gel electrophoresis and interpret the results • Understand the use of VNTRs in DNA fingerprinting and its application in biological sciences.