Sigma Xi Undergraduate Showcase 2

Leonardo Gomes Title: Structure, Function, and Medical Applications of the Botulinum Neurotoxin type A (BoNT/A) The biotherapeutic known as botulinum neurotoxin type A (BoNT/A) is produced by Clostridium botulinum and is famous as one of the most poisonous biological toxins. However, when used in controlled quantities, it can be a very useful treatment and is applied both in the management of muscle disorders and for the purpose of smoothing out wrinkles. The objective of this presentation is to describe how BoNT/A works at a molecular level by connecting its protein structure and catalytic activity to the different medical and cosmetic uses it has. The active toxin is a 150 kDa protein made up of two chains joined together by a disulfide bond, specifically a 100 kDa Heavy Chain (Hc) and a 50 kDa Light Chain (Lc). The Heavy Chain first binds to motor neurons via a 'dual-receptor' system by interacting with both the membrane gangliosides and the synaptic vesicle protein SV2. After the nerve cell has taken up the toxin by endocytosis, the acidic condition inside the endosome causes the translocation domain (HN) of the Heavy Chain to change shape and to form a channel, thus enabling the catalytic Light Chain to transit across the membrane and enter the cytoplasm. Inside the cell, the Light Chain acts as a zinc metalloprotease having the typical HEXXH +E catalytic sequence and cuts one peptide bond between Gln197 and Arg198 on SNAP-25, thus removing nine amino acids. Even though the fragment which is removed is small, this cleavage prevents the SNARE complex from assembling properly and consequently stops the release of acetylcholine, causing a temporary paralysis of the muscle without killing the neuron. The presentation also examines how this molecular blockade is put into use in real-life situations. Apart from being used to relax facial muscles for cosmetic anti-aging and helping to alleviate painful muscle spasms in conditions like cervical dystonia, BoNT/A is employed to stop over-sweating (hyperhidrosis) by blocking the cholinergic signals which get to the sweat glands. It has a number of interesting cosmetic applications as well, for instance the well-known treatment called "hair Botox". This presentation demonstrates that by studying protein structure and enzyme catalysis we can turn a deadly bacterial weapon into a precise medical tool. About the presenter: Leonardo Gomes is an Honors in Major (Biology)senior undergraduate student at Nova Southeastern University majoring in Biology with minors in Business and Pre-Health. Through his coursework, he has developed a strong interest in understanding human health and pharmacology, with a particular focus on drug mechanisms and the biochemistry of therapeutic proteins. Outside the classroom, he has completed extensive clinical shadowing alongside plastic and reconstructive surgeons, where he gained insight into patient care, surgical procedures, and the day-to-day realities of aesthetic and reconstructive surgery. These experiences solidified his fascination with aesthetic and reconstructive medicine, as well as the practical applications of injectable pharmaceuticals. Following graduation, he plans to attend medical school to pursue a career as a plastic surgeon, hoping to combine a dedication to surgical technique and clinical care with his background in biochemistry and healthcare. Nyobi Fleming Title: Discovery of Antibiotic-Producing Bacteria from Harvester Ant Mound Soil from the Black Hills, South Dakota The increasing prevalence of antibiotic resistance underscores the need to investigate environmental bacteria as sources of antimicrobial compounds. Through the Tiny Earth initiative, this study evaluated the antibacterial potential of bacteria isolated from harvester ant mound soil collected near Rochford in the Black Hills of South Dakota. Serial dilution and culture-based isolation yielded nine bacterial isolates, which were screened for antimicrobial activity against safe relatives of ESKAPE pathogens. Two isolates demonstrated antibacterial activity, with library plate isolate numbers 3 and 5 producing clear zones of inhibition against Acinetobacter baylyi and Escherichia coli, respectively. Preliminary molecular characterization using 16S rRNA gene amplification, sequencing, and BLAST analysis supported the tentative identification of one active isolate as Bacillus sp., while the second remained taxonomically unresolved. Whole-genome sequencing is being conducted to support further taxonomic characterization and investigation of biosynthetic potential. Bacterial extracts have been obtained via ethyl acetate extraction, and a chemical analysis has also been completed using mass spectrometry. Future work will focus on interpreting the genomic and mass spectral data to identify biosynthetic gene clusters associated with secondary metabolite production. Integrating these analyses with the observed antibacterial activity will guide further investigation of candidate antimicrobial metabolites. These findings support harvester ant mound soil as a source of bacteria with antibacterial activity and establish a foundation for continued genomic and chemical characterization. About the Presenter: Nyobi Fleming is a sophomore at Nova Southeastern University, double majoring in Medical Humanities and Biology. Originally from Sarasota, Florida, she is a Razor’s Edge Research Scholar with interests in antibiotic resistance, microbiology, and the intersection of science and patient care. Her research experiences include antibiotic discovery through the Tiny Earth initiative and a summer research internship with the Duke–UNC PREMiEr program, studying the built environment microbiome. Nyobi hopes to pursue a career combining medicine and research. Outside the laboratory, she serves as president of Girls Who Lead and enjoys connecting with others through leadership, service, and dance. Aayush Doshi Title: Gathering College Students' Interests in Bone Health by Promoting Vitamin K2 Consumption The human skeleton requires constant sources of nutrients (calcium, vitamin D3, vitamin K) for bone remodeling, maintaining bone mass, and bone density. While there is existing evidence regarding the benefits of calcium and vitamin D3 on bone health, there have been recent studies of the effects of vitamin K derivatives (vitamins K1 and K2) on bone maintenance. The growing popularity of the new over-the-counter supplement named "Vitamin D3 + K2" has initiated our interest in a deeper understanding of the mechanisms of the vitamin K derivatives' roles in bone health regulation. Vitamin K is a fat-soluble vitamin that naturally exists as phylloquinone (K1) and menaquinone (K2), which differ in sources and physiological function. Vitamin K1 is found in leafy greens and promotes liver production of blood-clotting factors II, VII, IX, and X, while vitamin K2 is found in fermented foods and assists in the regulation of calcium deposition into the bones. As consumer interest in supplementation increases, we aim to promote the consumption of natural sources of vitamin K2 and provide explanations of the benefits of alternatives to over-the-counter supplements. Our research aims to raise awareness about preventative dietary care from a young age to build a strong skeletal system. Our population of interest is a group of students to whom we administer surveys to gather their opinions and reflections on our presentation on the holistic approach to maintaining bone health. About the presenter: Aayush Doshi is a junior biology major at Nova Southeastern University, pursuing minors in Public Health, Nutrition, and Research Studies. He is a member of the Razor’s Edge Research Program and NSU’s dual admission osteopathic medicine program. His passion for preventive care centers on how nutrition and everyday habits can support long-term health. Through his work on a project promoting vitamin K2 consumption, he explores ways to engage college students in bone health. As a future physician, Aayush believes in empowering people with the knowledge and resources to make informed choices that support healthier lives.