Using Position Effect Varigation to Quantify Telomere Elongation

sample on microscope tray

Students

2021
College

Faculty

Assistant Professor of Biology

Project Summary

This summer I participated in the Penn Undergraduate Research and Mentorships Program alongside Professor Mia Levine, working on research involving domesticate retrotransposons in drosophila telomeres. Over the course of the summer I engaged with the various equipment and techniques utilised by the lab to study the epigenetics of fly telomeres. This included proper dissection techniques for removing and squashing larval salivary glands as well as an introduction on how to further prepare these samples for imaging. In order to prepare for my project I was also introduced to the fundamentals of using drosophila as a model organism, such as preparing and maintaining fly stocks, sorting and collecting from vials, and setting up crosses.

The project which my poster focused on using eye variegation produced by the relative placement of a transgenic insertion to serve as an indicator for telomere growth in Drosophila following the replacement of a gene coding for a retrotransposon regulating element. To do this, flies bearing a variegated eye phenotype were crossed with flies which had their normal version of their retrotransposon regulating gene, and those which had an ancestral variant replacing it. These flies bearing variegated eyes had the gene coding for their natural red eye pigmentation knocked out and reinserted at the border between the open and expressed euchromatin of the genome, and the tightly packed and suppressed heterochromatin, leading to some eye cells expressing this gene, while others did not. These flies were crossed with male flies bearing the telomeres of normal and increased length, the principle behind this being that due to telomeres recruiting heterochromatin, especially to their ends, this would draw heterochromatin away from the border where the red pigment gene was re-introduced, increasing its expression.

Working with this project not only allowed me to learn several valuable techniques used commonly in cell biology and fly genetics, but afforded me the opportunity to see how actual research is conducted, and the steps that need to be taken to design, prepare, and perform an experiment fit for publication. As such, I feel that this program provided some genuine insight as to what I might expect from a future career in research, particularly in academia.