Title page for ETD etd-06252007-095106


Type of Document Dissertation
Author Coy, Monique Royer
URN etd-06252007-095106
Title Dd34e Dna Transposable Elements of Mosquitoes: Whole-Genome Survey, Evolution, and Transposition
Degree PhD
Department Biochemistry
Advisory Committee
Advisor Name Title
Tu, Zhijian Jake Committee Chair
Adelman, Zachary N. Committee Member
Gillaspy, Glenda E. Committee Member
Kennelly, Peter J. Committee Member
McDowell, John M. Committee Member
Keywords
  • interspersed repeat
  • mosquito
  • DNA transposable element
  • evolution
  • gambol
  • horizontal transfer
  • Tc1
  • transposition assay
Date of Defense 2007-06-13
Availability unrestricted
Abstract
Transposable elements (TEs) are mobile genetic elements capable of replicating and

spreading within, and in some cases, between genomes. I describe a whole-genome

analysis of DD34E TEs, which belong to the IS630-Tc1-mariner superfamily of DNA

transposable elements, in the African malaria mosquito, Anopheles gambiae. Twenty-six

new transposons as well as a new family, gambol, were identified. The gambol family

shares the DD34E catalytic motif with Tc1-DD34E transposons, but is distinct from these

elements in their phylogenetic relationships. Although gambol appears to be related to a

few DD34E transposons from cyanobacteria and fungi, no gambol elements have been

reported in any other insects or animals thus far. This discovery expands the already

expansive diversity of the IS630-Tc1-mariner TEs, and raises interesting questions as to

the origin of gambol elements and their apparent diversity in An. gambiae. Several

DD34E transposons discovered in An. gambiae possess characteristics that are associated

with recent transposition, such as high sequence identity between copies, and intact

terminal-inverted repeats and open reading frames. One such element, AgTango, was also

found in a distantly related mosquito species, Aedes aegypti, at high amino acid sequence

identity (79.9%). It was discovered that Tango transposons have patchy distribution

among twelve mosquito species surveyed using PCR as well as genomic searches,

suggesting a possible case for horizontal transfer. Additionally, it was discovered that in

some mosquito genomes, there are several Tango transposons. These observations

suggest differential evolutionary scenarios and/or TE-host interaction of Tango elements

between mosquito species. This strengthened the case that AgTango may be a functional

transposase, and I sought to test its potential activity in a cell culture-based inter-plasmid

transposition assay using the Herves plasmids as a positive control (Arensburger et al.,

2005). AgTango constructs were successfully constructed; however, no transposition

events were detected for Tango or Herves. Because the positive control failed to work, no

assessment can be made concerning Tango's transposase. Possible causes and solutions

for these results, alternative means to detect transposition, as well as future directions

with Tango are discussed.

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