Methodology involved in the investigation of the role of different tissues and organs in the clearance response to acute bacterial challenge in the American Lobster

Author: Braden Wright
Major: Biology
Approved: Spring 2019
Status: Completed

The American lobster (Homarus americanus) is capable of mounting an impressive immune response to acute bacterial infection. The animal will release phagocytotic hemocytes (which are analogous to human white blood cells) into their hemolymph in order to engulf pathogenic organisms and clear the infection. The hemocytes will clot around the invading cells and carry them out of the body. Previous research has shown that specific tissues are essential for this physiological mechanism to take place, including the heart, gills, nephridial kidneys, and urinary bladder. This project will aim to take a closer look at the histological role in the clearance of infection. To characterize the role of these tissues, lobsters will be infected with a modified version of the bacteria Vibrio campbeffii that has been engineered to express green fluorescent protein. Tissue samples will be taken of the heart, gills, nephridial kidneys, and urinary bladder and a cryostat will be used to prepare thin sections. We will look at the amount of bacteria present in each organ via confocal and fluorescence microscopy. Fluorescence microscopy is a method of microscopy that uses fluorescence to generate an image as opposed to light reflection. This allows for a higher resolution of the material, but often requires long exposure times. Confocal microscopy is a way to overcome the limitations of fluorescence microscopy by blocking the out-of-focus light from the sample and enhancing image resolution.