| Description |
Embryonic development is one of the most critical stages of the life cycle for most eukaryotic organisms. Extrinsic and intrinsic signals must be perceived and transduced to facilitate proper organization of a body plan. Cellular components must then be selectively segregated to different parts of the embryo and accompanying morphological changes must be precisely positioned. To aid the cell in orchestration of these dynamic events, the cytoskeleton performs many tasks, including structural support, organelle positioning, vesicle transport, and localization of polarity molecules. While microtubules have been extensively examined in vascular plants and animals, much less is known about their roles in the stramenopile lineage. In the brown alga Silvetia compressa, I examined the structural and functional roles of microtubules during early development. In contrast to previous reports, I found that microtubule arrays become asymmetrically oriented toward the apex of the rhizoid pole during polarization. These microtubule arrays organize the endoplasmic reticulum and target it toward the rhizoid pole. I also showed that the phospholipase D and phospholipase C signaling pathways are functional in brown algae and are needed for organization of the cytoskeleton Finally, I examined the microtubule-associated motor protein Kinesin-5 (Eg5) during spindle assembly and highlighted its functional similarities and differences with vascular plants and animals. This work has yielded insights into conserved and novel traits possessed solely by brown algae and has led to a significant revision of the model for early development. |
