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Methods to investigate Cilia:


 * 1) Fluid shear stress - A fluid force is applied perpendicular to the cilium and the velocity of the fluid is measured.
 * 2) FRAP (fluorescence recovery after photobleaching) - A section of the cilia is photo-bleached and receptors or proteins are fluorescently tagged to quantify when and where they reappear in the photo-bleached section to determined localization patterns.
 * 3) Calcium Imaging - The intracellular calcium levels are measured by a fluorescent sensor that can quantify the amount of calcium that was released as a result from a mechanical or chemical stimuli.
 * 4) Calcium oscillations - Uses fluorescently tagged calcium to quantify the intensity of the oscillating fluorescent signal over time in the cell as cilia is responding to stimuli.

Sensing the extracellular environment

Mechanosensation

Mechanotransduction is needed to keep a cell in homeostasis. Cilia help the cell sense the mechanical stimuli and respond accordingly.

Embryogenesis

Motile cilia in the node move fluid to surround the embryo, primary cilia sense this fluids presence and movement and tell the cell when to begin differentiation based on the location of the fluid. Symmetry forms at a junction called the left right organizer to give the embryo left right asymmetry. This initiation of symmetry occurs when primary cilia sense fluid. The cytosolic calcium begins to oscillate in the cell as a response to the cation channel on the cilia, polycystin-2 (Pkd2) binding calcium.

Kidney function

Fluid flows through nephrons to filter the blood. The primary cilia on the epithelium of the kidney cells detect the flow through the nephrons which triggers a mechanosensory signal to influx intracellular calcium. The endothelium of blood vessels are lined with primary cilia that regulate nitric oxide production and cytosolic calcium by sensing the fluid shear stress.