Term of Award

Spring 1994

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)


Department of Biology

Committee Chair

D. K. McLain

Committee Member 1

William S. Irby

Committee Member 2

John W. Parrish

Committee Member 3

Oscar J. Pung


The nature of compensatory base changes and the extent of interspecific and intraspecific variability in the D3 region of the 28S rRNA gene were investigated by sequencing ten samples of the D3 region DNA from ticks {Ixodes scapularis [2 samples], Ixodes persulcatus, Ixodes affinis, Rhipicephalus pulchellus), an insect (Chauliognathus pennsylvanicus) and, a fish (Fundulus heteroclitus [4 samples]). D3 DNA was subcloned into plasmid vectors after PCR amplification using conserved primers. Sequence data were analyzed by PC Gene Package and compared with published data for Drosophila melanogaster and Mus musculus. Intraspecific sequence variation in Fundulus heteroclitus was low, but high in Ixodes scapularis. Although the D3 segment sequences varied tremendously between taxa, the secondary structure of the corresponding transcripts showed some similar structure, indicating substantial compensatory base evolution and secondary structure constraints on the evolution of the D3 expansion segment.

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