Document Type


Date of Degree

Spring 2009

Degree Name

MS (Master of Science)

Degree In


First Advisor

Debashish Bhattacharya

First Committee Member

Josep Comeron

Second Committee Member

John Manak


Transposable elements (TEs) are acknowledged sources of genetic change within organisms. The effects of transposition can range from the disruption or creation of a single gene to large-scale genome rearrangements. Transposition events can result in beneficial mutations which allow an organism to adapt to a new environment. In the last three years, several studies have reported that some miRNAs, small RNAs involved in post-transcriptional gene regulation, have evolved from TEs. miRNAs play an important role in the stress responses of many organisms. Interestingly, TEs are derepressed under the same stress conditions that miRNAs are known to ameliorate. The observation that miRNAs are known to evolve from TEs and that TEs are derepressed under stress conditions lead me to question whether TEs play a role in environmental adaptation through the creation of small RNA networks. To test this idea, Chlamydomonas reinhardtii cultures were grown under low carbon, nitrate enriched conditions and the small RNA pool was analyzed. I found that these conditions do stimulate the expression of novel small RNAs and that some of these RNAs and their targets are derived from transposition events.


Chlamydomonas, low CO2, miRNA, nitrate, Transposable elements


vii, 37 pages


Includes bibliographical references (pages 34-37).


Copyright 2009 Heather Marie Tyra

Included in

Biology Commons