Ciliary driven flows: Linking the micro- with the macroscopic dynamics

Essential functions for life that range from swimming in single cell protists to mucus clearance in humans require the generation of long range flows with a specific topology. To generate these large scale flows thousands of micrometer-scale motile cilia must integrate their activity across centimeter-scale surfaces. The goal of our lab is to identify the key physical properties of individual cilia that control the collective phenotypes of a ciliary array and the structure of the flow it generates. To truly understand how physical observables interface with biological mechanisms we aim to uncover the molecular pathways that control these key parameters.

Spatial organization in ciliary arrays

In vivo the spatial organization of multiciliated cells and tissues is subject to several constraints. For instance, multiciliated tissues need to accomodate a variety of cell types, leading to areas devoid of cilia activity along a tissue. Furthermore, cilia must orient relative to each other within each cell and across the plane of the epithelium. Using a combination of live microscopy, molecular perturbations and quantitative image analysis we study how changes to the spatial organization of a ciliary array impacts the topology of the flows generated by it. We explore this question using the airway epithelium and multiciliated unicellular protists as models.

Physical properties of the fluid environment

Ciliary arrays in organisms across the tree of life are exposed to environments with diverse physical properties. While ciliated protists swim in water, the airway epithelium propels a thin layer of mucus. We are puzzled by the mechanisms that allow for proper function of ciliary arrays in these diverse physical contexts. To gain insight into this conundrum we study the planarian S. mediterranea. Planarians glide by secreting mucus on their ventral surface and use motile cilia to move the mucus. Their ventral epithelium is exposed, making this system amenable to perturbations in the surrounding fluid in vivo. By understanding how changes in the fluid impact flow properties and organism motility we aim to uncover the role of the physical environment in the function or a ciliary array.

Cytoskeleton of ciliated protists

Ciliates are large (hundreds of microns long) unicellular organisms. The surface of these cells is covered by cilia, organized in rows, that form intricate cortical patterns. Cilia and their associated structures are anchored to a filamentous sub-cortical cytoskeleton known as the epiplasm. This layer has different architectures in the different ciliate groups. We are interested in understanding the mechanisms that pattern this shell and the ciliary array it anchors. Furthermore, we aim to elucidate the biophysical mechanisms that allow the ciliate cortex to support the remarkable behaviors seen in these organisms such as rapid swimming and extreme shape changes.