September 20, 2023

2023 Nexus Scholars Speak on Summer Science Research 

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The Nexus Scholars Program hosted 99 undergraduates from the College of Arts and Sciences this past summer, providing them an opportunity to engage in eight and a half weeks of research at the University in topics ranging from Asian studies to neurobiology. 

Designed for students who have minimal research experience, Nexus requires applicants to rank three of their preferred choices from a list of faculty mentors — also known as principal investigators — or choose a PI who is not on the list.

Prof. Sylvia Lee, molecular biology and genetics, who is also an inaugural Nexus PI, worked with Tenzin Dhasel ‘25 over the summer to study the role of nutrition on fertility in C. elegans, a model organism for studying genetics. 

The team specifically focused on NHR-49, a nuclear hormone receptor in C. elegans.

A nuclear hormone receptor is a transcription factor — a protein that controls the rate of transcription of DNA to mRNA — whose activity is regulated by the hormone bound to them. 

In the first part of a two part project, Dhasel investigated the effects of the C. elegans’ diet on controlling its localization to the nucleus. Localization refers to the process by which a complex such as a protein is transported or maintained in a specific location.

NHR-49 is localized to the nucleus when a ligand — a molecule that binds to a protein — binds to it. Dhasel focused on how changing the diet to remove the ligands would affect this nuclear localization. 

C. elegans have two ligands, bmeth#1 and becyp#1, that bind to NHR-49. While bmeth#1 comes from within the worm, becyp#1 is produced by the bacteria that the model organism preys upon.

After discovering these two ligands at the Schroeder Lab, they focused on the interaction between the ligands and how food could affect the transcription factor NHR-49, which is important in regulating fat metabolism for obesity and diabetes.

To remove bacterial ligand becyp#1, Dhasel fed the worms bacteria that did not have becyp#1 while the other ligand was removed by mutating the worms. She found that while there wasn’t a clear difference in nuclear localization between the first-generation of worms, worms that produced the ligand and were not fed the bacteria saw a decrease in nuclear localization in second generation worms. 

The second part of her project then focused on how NHR-49 could affect oocyte activation in feminized worms. While mutations in a sperm gene lead to the production of oocytes — immature eggs — and no sperm in feminized worms, mutations in NHR-49 in these feminized worms led oocytes to act as if there was sperm present. This resulted in the production of excessive unfertilized oocytes. 

When both ligands in the feminized worms were removed, Dhasel hypothesized that it would also lead to excessive oocyte production. She found that was not the case, raising the question of whether another ligand was associated with NHR-49. Dhasel plans to further investigate this as she continues research in the Lee Lab. 

“In my previous research lab, I didn’t do any projects. Since it was my first research experience, I had to learn the basic research skills,” Dhasel said. 

Her project has larger implications related to how different changes to reproduction are related to longevity and healthy aging. This is relevant when preventing and treating certain age-related diseases, including neurodegeneration and late-onset diabetes. 

Serah Dureus ’25, who also had some lab experience prior, echoed similar sentiments about gaining new experiences through the program. 

“Previously, I did a little research in a chemistry lab, but I really wanted to do something that centered around biology,” Dureus said. “I tried cold-calling professors to biology labs I was interested in, but that didn’t go anywhere…That’s why I thought [Nexus] was a great opportunity to try and do some research in that area.”  

Dureus worked in the Feschotte Lab under Prof. Cedric Feschotte, molecular biology and genetics, investigating regeneration in zebrafish and how transposons — highly repetitive sequences of DNA — may inhibit the regeneration process.

“Transposons are almost viral-like because they can hop out of the genome and paste itself somewhere else, which can be destructive,” Dureus said. “So, we thought that was inhibiting the regeneration process and looked into that by injuring the zebrafish eye and seeing how regeneration occurs,” Dureus said. 

Although the results from her summer project were inconclusive, Dureus also plans to continue her research in the lab throughout the fall semester. 

“I didn’t really know what research was for undergraduate students,” Dureus said. “I had the wonderful opportunity to do Nexus, and I enjoyed every second of it, and I’m so grateful for the opportunity.” 

Correction, Sept. 21, 2:02 p.m.: A previous version of this article incorrectly stated the number of participants in the Nexus Scholars Program. The article has been corrected.

Brenda Kim can be reached at [email protected].