Date Approved

2007

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Biology

Committee Member

David Kass, PhD, Chair

Committee Member

Michael Angell, PhD

Committee Member

Tamara Greco, PhD

Abstract

Short interspersed DNA elements (SINEs) and long interspersed DNA elements (LINEs) represent two families of transposable elements (TEs) within mammalian genomes. About 45% of the human genome consists of TE derived sequences. SINEs do not encode protein, so they cannot be autonomously propagated and require additional cellular machinery, most likely LINE proteins (ORF1p and ORF2p), for their mobilization, which has been supported by a cell culture-based retrotransposition assay. SINEs are ancestrally derived from either the 7SL RNA gene or from various tRNA genes. Sequence data support the co-evolution of some tRNA-derived SINEs with LINEs. This study involved testing whether or not tRNAderived SINEs could mobilize in the absence of LINE ORF1p, as well as assessing a coevolution of both SINEs and LINEs using the retrotransposition assay. A series of SINE constructs containing Alu, B2, and B1 elements were created and analyzed. No evidence to support a co-evolution of SINEs and LINEs was found; however, it was discovered that tRNA-derived SINEs do not require ORF1p to mobilize. Interestingly, both tRNA and 7SL RNA-derived SINEs mobilize more effectively in the absence of ORF1p.

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