PSU study seeks to shed light on the inner-workings of cells

Portland State University recently received a $460,000 grant in support of a study that aims to answer questions about how “regular” nuclear genomes and smaller mitochondrial genomes coevolve enabling cells to maintain essential functions. The study will also examine the role of reproductive systems in that evolutionary process.

The National Science Foundation awarded the grant to biology associate professor Suzanne Estes and co-investigators Vaishali Katju and Ulfar Bergthorsson of the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University. The researchers will conduct the first comprehensive assessment of the coevolution of nuclear and the mitochondrial genomes under different reproductive systems. The study will provide critical data on intracellular genetic mechanisms essential to energy metabolism in many living organisms.

The vast majority of biologically useful energy is generated within the mitochondria, tiny organelles that exist within eukaryotic cells. The processes that produce energy depend on the cooperation of specific protein complexes encoded by both mitochondrial and nuclear genomes. The mitochondrial genome, however, mutates at a faster rate than the nuclear genome. As those mutations can alter the proteins needed for energy production, the nuclear genome coevolves to compensate. This “mitonuclear” coevolution supports continuing metabolic activity and is the focus of the research team’s study.

Estes and colleagues will use C. elegans, a species of roundworm, as a model for the study. C. elegans can reproduce by both self-fertilization and sexual outcrossing and can produce as many of 80 generations per year, making it ideal for experimental evolution studies. By analyzing the mitochondrial and nuclear genomes of individuals bred under different reproductive systems over generations, the researchers will explore how genetic material coevolves over time. The study could lead to the discovery of novel mutations in the nuclear genome that counteract the adverse effects of those in the mitochondrial that could disrupt metabolism. The study will also provide data on how different reproductive systems affect evolutionary processes.

“We’re trying to understand the properties of mutation that ensure coevolution between mitochondrial and nuclear genomes,” Estes, an evolutionary biologist, said. “The way that coevolution is maintained is somewhat of a mystery. This study will shed light on that mystery.”

The results of the study will provide improved insights into the inner-workings of cells and may have far-reaching impacts for scientists studying evolutionary processes, human genetic diseases, cancer, and aging.