Date of Award

5-2021

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Steven Ackerman

Second Advisor

Michael Shiaris

Third Advisor

William Hagar

Abstract

Like vertebrates, invertebrates are susceptible to infection by bacteria, fungi and viruses. Antimicrobial proteins and antimicrobial peptides (AMPs) are important animal host defense molecules that play a significant role in the survival against invaders. Molecules exhibiting varying levels of antimicrobial activity have been identified in numerous species. The focus of this project was to isolate and characterize AMPs in the body fluids and mucus secretions of ctenophores and cnidaria. Mnemiopsis leidyi (Comb Jellyfish) and Aurelia aurita (Moon Jellyfish) were used to conduct experiments. These organisms were chosen because they have been in existence for millions of years and continue to thrive with what appears to be a less complex defense system than vertebrates. These organisms are bathed in an estimated 109 bacteria and 1010 viruses per liter of seawater, and with only a barrier of a gelatinous body are capable of warding off microbes. To investigate the antimicrobial properties of jellyfish, samples collected from offshore waters were subjected to biochemical and molecular analyses. Antimicrobial activity was identified using ultrafiltration, SDS-PAGE, HPLC, PCR and bacterial lysis assays. Bacterial lysis assays were conducted to detect antibacterial activity against gram-positive and gram-negative bacteria. Antibacterial assays showed that there was a <500 dalton (Da) protein fraction isolated from both species that exhibited bacterial growth inhibition. The peptides were characterized using column chromatography, HPLC, and SDS-PAGE while sequences obtained from PCR studies yielded identities consistent with those of alpha helical peptides. The isolation and study of endogenous AMPs from invertebrates show promise in understanding the evolution of immunity as well as in developing new therapies to help in the fight against human diseases.

Comments

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