Matthew C. Gibson and Kausik Si promoted to associate investigators, Rong Li renewed as investigator

Matthew C. Gibson is particularly interested in the genetic and physical processes that control the architecture of epithelia, which are highly organized layers of tissue that cover all body surfaces with an uninterrupted sheet of cells. Gibson started his scientific career defining the role of extracellular signals in regulating the growth and patterning of Drosophila imaginal discs, or flattened epithelial sacs that develop into different organs and appendages, such as eyes and wings, in adult fruit flies.

Since joining the Stowers Institute in 2006, Gibson extended his studies to exploring the integration between processes of cell proliferation and morphogenesis (the elaboration of shape) in epithelia as diverse as fly wings and sea anemone tentacles. Most recently, he defined the mechanism underlying nuclear movements during epithelial cell division, and showed that geometrical interactions between neighboring cells can determine the spatial orientation of cell division.
 

Kausik Si, who moved to the Stowers Institute in 2005, uses fruit flies to study the biochemical basis of long-term memory. He was the first to suggest that a protein with prion-like properties may be at the center of a series of biochemical changes at the connection points between brain cells that form the basis for memory persistence.

Working with the mollusc Aplysia, a popular model system to study learning and memory, Si and his colleagues later demonstrated that neuronal activity generates prion-like CPEB aggregates and, rather than poisoning a neuron like a real prion would, the transformed CPEB protein stabilizes connections between neurons. The latest study from his lab shows that, like Aplysia CPEB, an activated fruit fly version called Orb2 undergoes prion-like conformational changes, which are necessary to establish a persistent “memory trace.”

 

Rong Li’s multifaceted research program, which relies heavily on high-end imaging coupled with computational modeling, explores how cells—bundles of bustling matter, in Li’s words—impose order on seemingly loosely interacting and fluctuating components to accurately carry out complex tasks and specialized functions, time after time.

Li’s findings cover a lot of ground and frequently force scientists to rethink long-held assumptions. For example, most recently she demonstrated that aging yeast cells don’t require an active transport system to keep age-related “junk” out of daughter cells, but instead rely on cell geometry and slow diffusion rates to ensure daughters’ youthful state. She’s also found that mammalian oocytes rely on a powerful intracellular stream—instead of the more customary structural tethers—to position chromosomes far off-center to prepare for a highly asymmetrical cell division.