Author (Your Name)

Ruth B. Langton, Colby College

Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Biology Dept.


Andrea R. Tilden

Second Advisor

Cathy Bevier

Third Advisor

Josh Kavaler


Glutamate is the primary excitatory neurotransmitter in the mammalian central nervous system. It is of particular interest because of its supposed role in the processes of learning and memory, and also because of its potential toxic effects that have been linked to neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. Although glutamate is necessary for normal cell functioning, high levels of glutamate receptor activation can result in cell death, a phenomenon known as excitotoxicity. It has been suggested that glutamate also plays an important role in the insect and crustacean nervous systems, allowing for the examination of excitotoxicity in these organisms. The current study aims to determine the effect of high concentrations of glutamate on the neurite outgrowth of cultured fiddler crab (Uca pugilator) cells. Cells were obtained from the x-organ, a neurohemal organ located in the crustacean eyestalk, and were cultured for 24 hours in simple culture medium. After 24 hours, cells exhibiting neurite outgrowth were photographed and treated with one of four concentrations of glutamate. The treatment groups included: control with 0 mM glu, 0.1 mM glu, 1 mM glu, and 10 mM glu. After another 24 hours, the cells were photographed a second time and the neurite outgrowth was measured and compared. Higher concentrations of glutamate had a negative effect on neurite outgrowth, causing the neurites to retract or slow their growth. Glutamate receptors were also located in the x-organ cells using immunocytochemistry with fluorescence. This study provides insight into the workings of the crustacean nervous system and shows that fiddler crabs are a model organism in which to examine the effects of excitotoxicity, which may lead to future knowledge about the mechanisms of neurodegenerative diseases.


Glutamate, Fiddler Crab, neurotransmitter, central nervous system, Uca pugilator

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