Carolyn Jahn, PhD
Associate Professor of Cell and Molecular Biology
Feinberg School of Medicine
Research Interests:
Mechanisms of Genome Rearrangement in Ciliated Protozoa
During the sexual phase of their life cycle, ciliated protozoa dramatically reorganize their genome via two processes: a) chromosome fragmentation with telomere addition and b) precise deletion. In Euplotes crassus, these are abundant processes that can be readily studied in a synchronized cell population. Dr. Jahn’s long term interest has been in defining how these processes are carried out in such a global way and how they are controlled so that they occur in such a precise manner. She expects that the mechanisms at work will have broad implications for understanding how genomes evolve and how chromosome and genome structural integrity is maintained.
Identifying Genetic Modifiers in the Mouse
Several recent reviews of mouse genetics and the mouse genome project have noted that one aspect of mouse genetics that will be greatly facilitated by the completion of the genome sequence and that holds great promise for the modeling of human inherited disease (or disease susceptibility) is the ability to identify “modifier genes” (genes that modify the phenotype of a mutation). In other model organisms, the search for modifier genes is readily carried out by mutagenesis and screening, but this is impossible in mammals because of the number of animals that need to be examined. Nevertheless, modifiers can be identified in the mouse by examining the phenotype of a mutation on different inbred strain backgrounds. Because inbred strains are homozygous for a particular assortment of alleles, each strain provides a unique collection of genes and a unique genetic background. Many inbred strains have been well characterized and are known for their distinct differences in disease susceptibilities. The project that Carolyn Jahn has initiated while on sabbatical in Doug Engel’s lab, involves the search for genetic modifiers of the small maf genes, MafG and MafK. The Engel lab started this project by breeding the maf knockout mutations into different inbred strains to generate congenics (essentially differing from the inbred strain at only the gene being crossed into the strain). In the past year, Dr. Jahn has characterized the phenotypes of the mafG and mafK mutations in various combinations in two of these strains and have carried out a regimen of breeding to determine what sorts of modifiers we could potentially identify. She is currently carrying out whole genome scans to identify the chromosomal locations of potential modifiers.
