Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences



First Advisor

Dr. Robin Lewis Cooper


Ectothermic animals are susceptible to temperature changes such as cold shock with seasons. To survive through a cold shock, ectotherms have developed unique strategies. My interest is focusing on the physiological function of during cold shock and prolonged cold exposure in the fruit fly (Drosophila melanogaster) and crayfish (Procambarus clarkii). I used Drosophila melanogaster as a model system to investigate cardiac function in response to modulators (serotonin, acetylcholine, octopamine, dopamine and a cocktail of modulators) in acute cold shock and chronic cold shock conditions as possible mechanism to regulate heart rate in the cold. To examine if the dampened heart rate in the cold could still be enhanced by modulators or calcium loading, modulators and light-sensitive channelrhodopsin proteins were utilized to stimulate the heart. This light induced cardiac activation increased heart rate in all conditions, and potentially can be used for cardiac therapy in mammals. Also, the acute and chronic cold conditioned heart showed responsiveness to the above mention modulators. In examining how synaptic transmission is influenced by acute and chronic cold, the crayfish neuromuscular junction was used as a model. This is a good model as there are high and low output synapses to be investigated. The low output neuromuscular junction was enhanced in response to acute cold. The high output nmj increased in synaptic response to acute cold. In addressing chronic cold conditions, the nmj were physiologically assayed in their response to acute warm changes as well as influence of serotonin and octopamine. In chronic cold condition, the synaptic output was varied in enhanced and dampened responses to an acute warm environment. These junctions were enhanced in their synaptic output by serotonin and octopamine (100nM). In assessing, by HPLC assay, octopamine concentration increased in chronic cold crayfish. This suggests compensation in synaptic transmission in cold acclimation possibility via endocrine responses.

Digital Object Identifier (DOI)