One aim of modern cellular biology is to understand how all the cellular components may be assembled into a whole, living cell. How does a single cell develop? Still little is known about how cellular components may self-assemble and organize at a global cellular level. How do cellular components sense cell size, measure distances, and position cellular components at specific locations inside the cell? How does pattern formation occur in the single cell, to establish distinct functional domains?

Our laboratory studies primarily the fission yeast Schizosaccharomyces pombe, an excellent model organism ideal for studying cellular morphogenesis. Fission yeast are simple rod-shaped cells that grow at the cell tips and divide by medial fission. One feature that makes fission yeast so ideal for these studies on spatial control is that its shape, size and division habits are extremely reproducible. Therefore, it is possible to identify mutants that have aberrant cell shape, cell size or cell division patterns.

Fission and budding yeasts are evolutionarily distant, and aspects of fission yeast cell division and cell polarity are more similar to processes in animal cells than in budding yeast. For instance, as in some animal cells, localization of the sites of cell polarity and polarized growth are dependent on microtubules in fission yeast, but not in budding yeast. The advent of a sequenced genome, coupled with excellent genetics and cytology, now makes fission yeast a potent system for addressing many important questions in cell biology. See pombe link for more general information about fission yeast.

Our lab is interested in how a fission yeast cell establishes its "ends" and "middle." The interphase nucleus and microtubules are positioned by dynamics of the microtubule cytoskeleton. These components establish a cellular axis that positions cell polarity and cytokinesis factors. The plus ends of microtubules help to define the cell "ends" by delivering cell polarity factors such as tea1p to the cell tips. The position of the nucleus determines the "middle" by localizing cytokinesis factors such as cdc12p and mid1p in the vicinity of the nucleus. In both cytokinesis and cell polarity, we find that key proteins that regulate these processes are present in motile particles that 1) move on microtubules or actin to the middle of ends of the cell, 2) dock at the cell surface, and then 3) function to induce the formation of specific actin structures (the contractile actin ring for cytokinesis, and actin cables for cell polarity).