Date of Award

Spring 2005

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Wayne L. Hynes

Committee Member

Christopher Osgood

Committee Member

Robert E. Ratzlaff

Committee Member

Daniel E. Sonenshine

Call Number for Print

Special Collections LD4331.B46 S344 2005

Abstract

In response to microbial challenge, invertebrates rely on their innate immune response to recognize and destroy harmful pathogens. One of the primary proteins produced by the response and that has been observed in many invertebrates, including insects, mussels, and ticks, is defensin. These proteins are responsible for forming pores in the membranes of invading microbes thereby destroying them. This study examined the gene coding region for defensin in two important tick disease vectors, Dermacentor variabilis and Ixodes scapularis. PCR amplification of the genes from tick chromosomal DNA resulted in the amplification of a 225 base pair amplicon. Sequencing of the PCR amplicons indicated that the nucleotide sequence encoded for defensin, and that it was the same sequence as that obtained from RT-PCR amplification of mRNA. Due to the fact that the chromosomal DNA and cDNA sequences were identical, and no other forms were found, it appears as though the defensin gene occurs as a single copy gene within the tick genome. PCR and sequence analysis also lead to the conclusion that there were no introns within the gene sequence. These results allow for further characterization of the ticks' innate immune response and how the ticks avoid infection by the microbes that they transmit.

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DOI

10.25777/fstq-ha22

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