Genetics of Model Systems

Headshot of Helen Lai

Helen Lai
Lew Lab

In the Lew lab, we study the mechanisms underlying cell polarity establishment and maintenance. We use the budding yeast, Saccharomyces cerevisiae, as the model organism because 1) it is genetically tractable, and 2) the genes and processes we study are highly conserved among various organisms. Our approaches include molecular genetics, light microscopy, and mathematical modeling. We have been able to ask fundamental questions in cell biology, such as how yeast makes sure to make one and only one bud at each cell cycle.

My current project focuses on how polarization processes are temporally regulated. Just like humans, yeast has a “time schedule” for activities. My research has revealed that in yeast, polarity establishment, targeted exocytosis, septin assembly, and bud formation occur in a consistent order with predictable intervals. In everyday language, the questions I ask the budding yeast sound like this: “Why did you have lunch at 12pm today? Was it because you noticed that it was time for lunch ? Or, was it because it had been a few hours since breakfast and you were hungry?” In other words, I aim to understand if the timing of later events (eating lunch, or budding) depends on that of earlier events (hours after breakfast, or minutes after polarization). Alternatively, the timing of later events could be triggered by an independent clock (12pm, or the “lunch time” equivalent for a cellular timer). The results of my research will shed light on how cell polarity and morphogenesis are regulated in a timely manner.

micron finterval