Retraction Pili with Fluorescence and Interacting with Pillars (video) The City University of New York Share Print E-Mail Loading video... Caption Two examples of retraction of the Caulobacter crescentus pilus. On the left the fluorescent microscopy technique that enables to see single pilus retracting. On the right the micropillar assay used to measure the pilus retraction forces. Blockage of the pilus retraction indicates to the bacterium that it is close to a surface conferring it a sense of touch. Credit Jingbo Kan Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.