Xin Li

Degree Type

Honors Capstone Project

Date of Submission

Spring 5-1-2014

Capstone Advisor

Prof. Kenneth Foster, Advisor

Honors Reader

Prof. Jureepan Saranak

Capstone Major

Biomedical and Chemical Engineering

Capstone College

Engineering and Computer Science

Audio/Visual Component


Capstone Prize Winner


Won Capstone Funding


Honors Categories

Sciences and Engineering

Subject Categories

Biomedical Devices and Instrumentation | Biomedical Engineering and Bioengineering | Other Biomedical Engineering and Bioengineering


The goal of this research is to understand how a unicellular green alga, Chlamydomonas-reinhardtii, responds to red light (670nm) and sound waves, by monitoring the beating frequency of its two cilia, which control cell motility. Ciliary beating frequency (BF) is proportional to the production of ATP, mainly generated by photosynthesis. A photosynthesis inhibitor, 3-(3-, 4-dichlorophenyl)-1, 1-dimethylurea (DCMU) decreases ATP production by photosynthesis. I used DCMU as a tool to analyze the red light effect on BF.

In the process of studying the effect of red light, I unexpectedly discovered experimental conditions for unstable ciliary beating (as shown in the video). I did a computational analysis of the relationship between ciliary stiffness and BF, to help determine the mechanism of ciliary beating. I studied the initiation of a ciliary wave near the base of a cilium and simulated the effects of changes in the prestress (the static curvature of a cilium) on the wave shape of the ciliary beat.

The fact that the cilia of many organisms respond to mechanical stimuli led to the study of an effect of sound waves on the BF of C. reinhardtii. I designed a simple method to preliminarily test the effect of sound waves on the Chlamydomonas cell population, using phototaxis behavior as an indicator. The experiment quickly showed that the mechanosensor response competed with the photoresponse. I also showed that sound waves increased the ciliary BF of the negatively phototactic Chlamydomonas.

Li_Xin_2off1.avi (15615 kB)
Li_XinAnimation.mp4 (1697 kB)

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.



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