Professor of Biology

B.A., Kansas State University
Ph.D., University of California, San Francisco

Member of:
• Institute of Molecular Biology

The Bowerman lab uses genetics, molecular biology, and microscopy to study cytoskeletal regulation and function in the early Caenorhabditis elegans embryo. Beginning with the first mitotic cell division, the early embryo undergoes a sequence of five asymmetric cleavages. Figure 1 shows the first three mitotic divisions during embryogenesis; two of these are asymmetric.

These early divisions are largely responsible for establishing the pattern of cell fates required for normal embryonic development. The asymmetric divisions, with their stereotyped timing and mitotic spindle positioning, provide a rich context in which to use the powerful genetics of C. elegans to investigate cytoskeletal function.

The actomyosin cytoskeleton, including the non-muscle myosin II called NMY-2 (in red in the late anaphase mitotic one-cell stage embryo in Figure 2), is localized predominantly at the cell cortex. The actomyosin cytoskeleton is important both for generating anterior-posterior polarity, and for the execution of cytokinesis.

Microtubules (shown in green in Figure 2; DNA is in blue) form the meiotic and mitotic spindles, which capture and segregate chromosomes. During mitosis, astral microtubules contact the cell cortex and are important for proper spindle positioning. Current C. elegans research projects in the lab focus on the assembly and function of meiotic and mitotic spindles, cell polarity, cytokinesis, and mitotic spindle orientation in early embryonic cells.

More recently, Stephan Schneider (a postdoctoral fellow in my lab) has also initiated studies of early development in the marine polychaete Platynereis dumerilii (Fig. 3 shows an adult female; image courtesy of Adriaan Dorresteijn ). This marine annelid belongs to the superphylum Lophotrochozoa, members of which undergo a widely conserved spiral pattern of cell cleavages during embryogenesis that, as in C. elegans, is invariant and characterized by asymmetric and asynchronous mitotic cell divisions.

We are using Platynereis to study the evolution of bilaterian animals, with the long-term goal being to better define the developmental programs that were present in the ancestor to all bilaterial animal phyla.