Characterization of phagocytic hemocytes within the hemolymph of the American cockroach

Abstract

Phagocytosis is a function of the immune system found across eukaryotes that is necessary for both innate and adaptive immune systems. Much of our current knowledge of immune functions traces back to the ability of specialized cells in an organism to recognize, engulf, and destroy particles. Insects are the largest numbered organisms on the planet with some estimatinges that 75% of all species of living organisms insects. This incredibly large and diverse order of organisms is often overlooked outside of a few species that have been used as model organisms. One such overlooked insect is the American cockroach (Periplaneta americana. These insects are cosmopolitan as they can be found in almost every environment. This includes close proximity to humans such that they are often encountering many of the same potentially deadly microorganisms, or have the possibility of being vectors of disease spread. The American cockroach could prove to be a useful model organism to study the effects of the microbiome on the immune system With this in mind there are two aims of this thesis research: 1) to identify which cells in the hemolymph of the American cockroach are the phagocytes using modern techniques such as flow cytometry; 2) to describe some characteristics of phagocytosis in conventional cockroaches to provide a foundation for future studies. The treatments tested in this study include incubation time, temperature, and different bacterial and fungal stimuli, as well as the use of peptides to inhibit phagocytosis.