Telomeres on a Treadmill: Causes and Consequences of Telomere Protein Evolution

detail photo of d. Melanogaster eye

Students

2020
College

Faculty

Assistant Professor of Biology

Project Summary

This summer I was fortunate to work at the Levine Lab in the Penn Biology Department. The lab explores the rapid evolution of certain chromatin proteins in drosophila melanogaster. My project’s focus was to explore the consequences of the rapid evolution of the specific protein HOAP.

HOAP is a protein which is part of a complex that protects the ends of linear chromosomes in flies thus being crucial for the survival of the organism. However, this protein has faced a very rapid evolution, presenting a surprising inconsistency; a highly conserved function that is mediated by a very rapidly evolving protein. To explore this phenomenon, we used drosophila melanogaster flies that had the gene that encodes the HOAP protein swapped for a version of HOAP from a closely related species of fly. This gave us an idea of what effects the evolution of this protein could have by exploring what was normal. What was puzzling was that the flies that had the swapped gene seemed to be alive and well. This was particularly interesting because the protein encoded by the swapped gene was a different version of the HOAP protein. Using immunofluorescence, we also saw that the swapped protein localized properly at the telomeres, suggesting that a large part of its function was still conserved regardless of the ample differences. By exploring the effects of the swap on the phenomenon of Position Effect Variegation we found that the swap does affect the stability of the complex HOAP is part of. This suggests that the rapid evolution of HOAP somehow alters the way the DNA at the telomeres is packaged.

Throughout my summer I got to explore and learn about some of the techniques often used in the biological sciences. Some of these included learning how to work with flies by maintaining crosses, identifying male from female flies and determining which flies were virgins. Fly work was not easy to grasp and I realized that the only way I could get better was by practicing and learning from the times I failed. Through practice, I also improved my fine motor skills by learning how to perform various larval dissections used to prepare slides stained with immunofluorescent antibodies.

I also learned many skills that, although not specific to biology, are useful nonetheless. I developed presentation and communication skills, which are necessary to show others what you have found; acquired organizational skills, which are crucial to properly keep the data collected; got insight into the way experiments are developed and how questions are asked in the world of research; and got to experience how science is a large portion failure and a small portion success. However, it is crucial to use these failures to learn. Throughout my time at lab I had to come up with inventive solutions for some of these failures, helping me develop my problem-solving abilities. There are still many things I would like to learn and I look forward to continuing my work with my mentor in the future