Alan C. Christensen
Ph.D. University of Washington, 1982
E205 Beadle Center
Mitochondria are widely known as the “powerhouses” of the cell. They are the site of respiration and most of the energy generation in cells. What is less widely known is the other roles they play in the lives of organisms, including regulating reproductive strategies and controlling programmed cell death. Mitochondria have their own DNA and genetic system, although they rely on the nucleus for synthesis of many of their proteins.
Plant mitochondria are considerably more complex than animal mitochondria. Their genomes are much larger – some are more than one million base pairs in contrast to the sixteen thousand base pairs found in human mitochondria. Plant mitochondrial genomes only encode slightly more genes than animal mitochondria do (54 genes in Arabidopsis vs. 37 in humans). Most of the extra DNA is of unknown function. The genes of known function are among the slowest evolving (fewest mutations per generation) known. At the same time, the genome rearranges readily and frequently and the noncoding parts of the genome are difficult or impossible to compare between species.
I am interested in the mechanisms of DNA replication, recombination and repair that maintain the mitochondrial genomes, as well as the mechanisms that allow them to expand and add so much noncoding DNA. I recently proposed a model to explain the simultaneous findings of low mutation rates in genes and high rearrangement and mutation rates outside of genes.
My current work includes developing a method for transforming Arabidopsis mitochondria, as well as studying mechanisms of DNA repair in mitochondrial genomes.
Member of the Genetics Society of America, the American Association for the Advancement of Science, and the American Society of Plant Biologists
University of Nebraska – Lincoln, College of Arts and Sciences Distinguished Teaching Award, 2008