The Bowerman lab uses molecular genetics and live cell imaging to study cytoskeletal regulation and function in the early Caenorhabditis elegans embryo. Beginning with the first mitotic division, the early embryo undergoes a sequence of five asymmetric cleavages. These early divisions are largely responsible for establishing the pattern of cell fates required for normal early embryonic development. These asymmetric cell divisions, with their highly stereotyped timing and mitotic spindle positioning, provide a rich context in which to use the powerful genetics of C. elegans to investigate cytoskeleton function during cell division and development.
The actomyosin cytoskeleton, including the non-muscle myosin II called NMY-2 (in red in the late anaphase mitotic one-cell stage embryo shown above) is localized predominantly to the cell cortex. The actomyosin cytoskeleton is important both for generating anterior-posterior polarity, and for cytokinesis. Microtubules (in green in the above figure; DNA is in blue) form both the meiotic and mitotic spindles, which capture and segregate chromosomes during cell division.
Current projects in lab focus on both oocyte meiotic spindle assembly, which occurs in the absence of the microtubule organizing centers called centrosomes, and mitotic spindle assembly, which is organized in large part by centrosomes. The movie below on the left shows Meiosis I and II in an oocyte after fertilization and during ovulation. A row of three oocytes are present on the left, with the spermathecum adjacent to the most mature oocyte, and mitotic embryos in the uterus are visible at the right. This movie was filmed using whole mount worms expressing a GFP fusion to tubulin to label microtubules in green, and an mCherry fusion to a histone to label chromosomes in red. The movie below on the right shows the first two rounds of mitotic division in an isolated early embryo (again with GFP labeling microtubules in green, and mCherry labeling histones in red).
(pulled from pubmed)
(pulled from pubmed)