The classification and evolution of Pokey, a DNA transposon in Daphnia

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Penton, Erin Heather
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University of Guelph

The recent explosion of newly reported eukaryotic transposable elements is illustrating their widespread nature, their ultimate importance as agents of evolution, and the genome as a dynamic entity. My thesis characterizes a transposable element, 'Pokey', found in the ribosomal DNA of 'Daphnia'. Through sequencing of full-length 'Pokey ' elements from 'Daphnia pulicaria', I have shown that it is related to 'piggyBac' and thus, is a member of the TTAA-specific family of DNA transposons. A phylogenetic analysis of the 3' -end of 'Pokey' elements from the subgenus ' Daphnia' showed that 'Pokey' persists via strict vertical transmission and has existed for long periods of evolutionary time, which is unusual for DNA transposons. 'Pokey' inserts into a region of the large subunit ribosomal RNA gene occupied by other elements and it seems likely that this region is an ideal genomic location for the evolution of insertion sequences.

Pokey, DNA transposon, Daphnia, eukaryotic transposable elements, ribosomal DNA