Lisa K. Johansen, Ph.D, Assistant Professor
Research Interests
The role of Arabidopsis RNA-dependent RNA-polymerase(s) in virus-host interactions, RNA silencing, and stress
The Arabidopsis genome codes for seven potential RdRps. Interestingly RdRps have not been identified in the drosophila or mammalian genomes. Why are there so many RdRps in Arabidopsis? What is the role of these individual RdRps? Are there redundant roles? Are some RdRps important for RNA silencing? Are some important for virus defense? Are some important in development? Can we identify unique situations where a plant would require an RdRp but a mammalian organism would not?
These are some of the questions we are tackling in the Johansen lab. We are approaching these questions by characterizing T-DNA insertion lines with one or more RdRp genes nonfunctional. We are taking a three-pronged approach to studying the functions of plant RdRps. First, we are looking at mutant plant development over time. Secondly, we are looking at the response of these mutant plants to virus infections. Third, we are studying the mutants at a molecular level, investigating the role of the RdRps in small RNA production. In addition, we are gathering bioinformatics data to analyze the expression of RdRp genes under normal and stress conditions.
By approaching these questions from a whole organism to a molecular perspective we hope to gain insights into the functions of these genes in Arabidopsis.
Current Projects in the Johansen lab
- Characterization of individual RdRp functions in RNAi
- Generation of double and triple RdRp mutant plant lines
- Use of microarrays in undergraduate teaching
Dr. Johansen is also the Director of the Biotechnology program
hhtp://thunder1.cudenver.edu/clas/biology/bioTechCert.html
In addition, Dr. Johansen head of the Colorado PREP Dissemination site
The Partnership for Research and Education in Plants (PREP) provides genuine research experiences to high school students and teachers while helping scientists to discover the function of previously uncharacterized plant genes.
link here: http://www.prep.biotech.vt.edu/Selected Publications
Chan SWL, Zilberman D, Xie Z, Johansen LK, Carrington JC and Jacobsen SE. (2004). RNA silencing genes control de novo DNA methylation. Science 303, 1336. Science(2004).pdf
Xie Z, Johansen LK, Gustafson AM, Kasschau KD, Lellis AD, Zilberman D, Jacobsen SE and Carrington JC (2004). Genetic and functional diversification of small RNA pathways in plants. PLoS Biology 2, 642-652 (open access at http://www.plos.org/) or RDR2 Function (2004).pdf
Zilberman D, Cao X, Johansen, LK, Xie Z, Carrington JC, Jacobsen SE (2004). Role of Arabidopsis ARGONAUTE4 in RNA-directed DNA methylation triggered by inverted repeates. Curr. Biol. 14, 1214-1220. Current Biol (2004).pdf
Carrington JC, Kasschau KD, Johansen LK (2001). Activation and suppression of RNA silencing by plant viruses. Virology 281, 1-5. Virology (2001).pdf
Johansen LK, Carrington JC (2001). Silencing on the spot. Induction and supression of RNA silencing in the Agrobacterium-mediated transient expression system. Plant Physiol 126, 930-938. Plant Phys (2001).pdf
Education
Postdoctoral Associate, 2000- 2004, Oregon State University: Center for Gene Research and Biotechnology.
Ph.D., 2000, University of Alabama at Birmingham, Microbiology
B.S., 1992, University of Washington: Biochemistry
Courses Taught
BIOL 4050/5050 Biotechnology Fall semester Biotech syllabus.pdf
BIOL 4124/5124 Molecular Biology of the Gene Fall and Spring Mol Bio syllabus.pdf
BIOL 4125/5125 Molecular Biology Techniques laboratory Spring semester