RUI: The Gene Stream II: From Sequence to Cell Function

Saint Olaf College, Northfield MN

Investigators

Abstract

Intellectual merit. Tetrahymena is an unusual organism that exists in nature as a single cell. As a ciliate, the unicellular Tetrahymena possesses not one, but two nuclei that are fundamentally different. The larger macronucleus is actively expressed and responsible for driving the daily activities of the cell. The smaller micronucleus is usually silent, and serves as a genetic archive for the cell, storing two copies of every gene that will be ultimately shared when the organism engages in nuclear exchange with a mating partner. In this regard, ciliates such as Tetrahymena resemble multicellular embryos, in which certain cells differentiate into the body (soma) of a developing organism while other cells are set aside to become a part of the germ line (future eggs or sperm). Remarkably, researchers have found that many of the same proteins that help distinguish the germline of an animal from the soma may play a similar role in distinguishing the germline micronucleus of a ciliate from the somatic macronucleus. Therefore, information gained in understanding the proteins of the germline and the soma of Tetrahymena will have broad scale applications in understanding differentiation as it occurs in larger, more complex multicellular systems. The project here is to explore the structure and function of the conjusome, a small intracellular structure found in mating Tetrahymena that resembles the P-granules in animal embryos that have been shown to house proteins that bring about genome modifications leading to the distinction between soma and germline. The investigators are also exploring a unique cell-cell junction, the nuclear exchange junction, that allows mating cells to trade nuclei with one another through a remarkable intercellular window. Three disciplines are brought together in this study: proteomics (the identification of genes from the protein constituents of an organelle), molecular genetics (knocking out genes by targeted mutation, and tagging gene products with fluorescent markers for microscopic observation in living cells), and bio-informatics, learning about a gene from the published Tetrahymena genome and through computer assisted searches of all the published genomes. Broader Impact The investigators' research program at St. Olaf College is specifically designed as a training vehicle for undergraduate researchers. The Gene Stream allows students to create sustained research projects that cross disciplines, from chemistry to biology and computer science, while maintaining a focused research goal, namely discovering the roles played by specific genes within a living cell. This cross-disciplinary program exposes undergraduates to the variety of experimental approaches and laboratory tools that scientists employ in the increasingly collaborative environment of modern research. The Gene Stream also provides our undergraduates with opportunities to travel to other University laboratories for specialized training as well as national and regional meetings where they present their work and receive feedback from graduate students, postdocs and PIs from graduate institutions. The investigators are extending their work with students in the laboratory by creating a workshop that provides a summer forum for college and university professors working in the field of Ciliate molecular biology to share expertise while weaving together an inter-collegiate research collaboration.