Date of Award

5-2011

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Chair

Shahid Karim

Committee Chair Department

Biological Sciences

Committee Member 2

Nan Wang

Committee Member 2 Department

Computing

Committee Member 3

Faqing Huang

Committee Member 3 Department

Chemistry and Biochemistry

Abstract

The Gulfcoast ticks transmit disease-causing pathogens to humans and animals. Rickettsia parkeri is notable among the pathogens transmitted by A. maculatum to humans. Heavy infestations of A. maculatum on animal ears cause them to become thickened and curled, a condition commonly called "gotch ear." The tick's multifunctional salivary glands are vital to their biological success and likely also play a critical role in transmission of disease; tick saliva contains a broad array of secretory products that facilitate prolonged tick attachment and feeding; disrupting tick blood feeding or inactivating key tick salivary proteins presents a novel strategy for tick-borne disease prevention. Sequencing of A. maculatum salivary gland normalized eDNA library revealed a gene sequence homologous to SelenoproteinM. Trace element Selenium exhibits a variety of functions in the form of Selenoproteins, most importantly, as an antioxidant enzyme. SelenoproteinM is expressed in A. maculatum salivary glands in almost all the feeding phases. RNA interference (RNAi) was used to assess the role of this molecule for tick feeding success. Silencing of was demonstrated by reduced transcript in salivary glands removed from partially fed ticks. Disrupting expression of SelenoproteinM by RNAi induced rapid weight gain in engorging female ticks in early phase of feeding. Since many Selenoproteins are involved in antioxidant activities, we further evaluated the antioxidant capacity of tick tissues treated with SeiM-dsRNA. There was a significant reduction in the antioxidant capacity in SelenoproteinM silenced tick tissues.

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