Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Christine Byrd

Second Advisor

Dr. John Jellies

Third Advisor

Dr. John Spitsbergen

Access Setting

Masters Thesis-Open Access


Removal of the olfactory organ in the adult zebrafish results in a significant decrease in volume of the ipsilateral olfactory bulb. Our lab has been investigating the potential role of apoptosis in this phenomenon. My hypothesis is that cells in the adult olfactory bulb normally undergo minimal apoptosis and that apoptosis will increase when sensory stimulation is removed. The TUNEL method allowed detection of cells undergoing DNA-fragmentation, which indicates an apoptotic response. Double-label immunohistochemistry was used to mark which apoptotic cells are neurons by using antibody to Hu, a neuron specific protein. Triple-labeling with bis-benzirnide confirmed the apoptotic nature of the response. In the normal adult olfactory bulb, TUNEL+ profiles are few and appear to be localized to the outer layers of the bulb. In deafferented animals, there is a significant increase in the number of TUNEL+ profiles. The apoptotic response occurs in two waves and is confined to the rostral half of the bulb. The first wave of cell death occurs 1 hour post-surgery. These apoptotic profiles appear to be primarily glial or immune in nature since they do not label with Hu. The second wave of cell death takes place at 24 hours and appears to decline to normal levels by 1 week. At the 24 hour time point some profiles are TUNEL+/Hu+ suggesting that there is a small population of neurons undergoing apoptosis.