Fernanda Lopez Bermejo

Fernanda moved to Michigan from Mexico 10 years ago. She attended high school in Rochester Hill before continuing her education at MSU. After completing her education at MSU, she will continue on to Physician Assistant school at Midwestern University in Illinois.

INVESTIGATING POTENTIAL PRECURSOR MOLECULES IN THE BIOSYNTHESIS OF TETRODOTOXIN IN NEWT ASSOCIATED BACTERIA 

Co-Author(s):  Faheed Shafau

Research Mentor(s): Heather Eisthen, Ph.D. 

Tetrodotoxin (TTX) is a potent neurotoxin found in organisms such as pufferfish, mollusks, and some amphibians. TTX blocks voltage-gated sodium channels, preventing action potentials and thereby causing paralysis. Little is 169 known about how TTX is synthesized, and no genes involved in synthesizing this molecule have been identified. The Eisthen lab discovered that TTX-producing bacteria can be isolated from the skin on rough-skinned newts (Taricha granulosa), and we are using strains of these bacteria to identify possible precursors in the TTX biosynthesis pathway. Previous researchers have suggested that arginine is a potential TTX precursor because both arginine and TTX contain a guanidinium group, an unusual molecular structure, and because arginine serves as a precursor for other guanidinium-containing toxins. However, before we test whether arginine contributes to TTX synthesis we must determine how it affects baseline growth of these strains. We measured growth patterns in 3 replicates of both Pseudomonas and Aeromonas strains in media supplemented with both L- and D-arginine, as both forms of the amino acid may be available to the bacteria in the environment on the newts' skin. We are currently repeating this experiment with L- and D-histidine supplemented media as a negative control, as histidine is positively charged like arginine, but lacks the guanidinium group that is hypothesized to enable TTX synthesis. After quantifying the effect of these amino acids on bacterial growth, we will assess the effect of amino acid supplementation on TTX production using LC-MS/MS to determine if TTX production is increased by supplementation of arginine.

Poster

Fernanda has shared her reflections on her membership in Drew Scholars:

“I met most of my friends from the Drew program.  From the beginning of college, we were all able to connect through the program. The program also helped me grow professionally.”

Fernanda’s words of wisdom to peers and successors:

“Try to meet as many people as you can in Drew because everyone is great and you’ll find amazing friends.”