Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cilia: 'The bouncer' of bacteria

08.09.2017

New paper by USC Viterbi School of Engineering Professor Eva Kanso and Professor Margaret McFall-Ngai of the Pacific Biosciences Research Center at the University of Hawaii elucidates the active role of cilia in regulating flow for bacteria filtering and

Imagine a club scene--a bouncer at a velvet rope selects which individuals get into the club. This, explains Eva Kanso, a professor of mechanical engineering at USC Viterbi School of Engineering, is what cilia do in an organism.


The squid's internal light organ features several different populations of cilia (green/blue) that coordinate their beating activity to recruit symbiont bacteria from the seawater and facilitate their migration to the pores (right side), where they enter the organ for life-long colonization.

Credit: Lab of Margaret McFall-Ngai, Pacific Biosciences Research Center at the University of Hawaii

Kanso applied the analogy to explain her new paper, "Motile cilia create fluid-mechanical microhabitats for the active recruitment of the host microbiome," co-authored with researchers from the Pacific Biosciences Research Center at the University of Hawaii at Manoa and from Stanford, to explain the active role that cilia have in ensuring certain bacteria are kept out of an organism while other symbiotic bacteria are selectively permitted to enter.

The paper, published in the Proceedings of the National Academy of Sciences, describes a framework for the role of fluid mechanics in letting symbiotic bacteria in an organism and enhancing chemical communication between the symbiont and the host organism.

... more about:
»bacteria »cilia »symbiotic bacteria

The results are contrary to previous research which assumes that cilia solely play a "clearance function." They could shed light on the role cilia--which are the size of one hundredth of a single human hair--play in human respiratory system and even in the reproductive systems and the brain. Their findings could also provide insights on how cilia dysfunction within organs affect for example, pulmonary conditions or infertility (how cilia help sperm reach eggs).

To learn about how cilia might work in the human body, Kanso, in collaboration with symbiosis expert McFall-Ngai and biofluid expert Janna Nawroth studied bobtail squid. The researchers examined how these squids in their nascent stage allow symbiotic bacteria Vibrio Fischeri to enter into their ciliated light organs, which play a crucial role in camouflaging the ink sacks of the otherwise translucent organism while they hunt for food at night.

The scholars sought to know: why does this bacterium gain access and why do all bacteria fail to accumulate within the squid's light organ? In addition, they sought to explain what, if any, is the role of cilia in allowing access?

Kanso and McFall-Ngai with lead authors Janna Nawroth, a principal investigator at Emulate Inc, and Hanliang Guo, a PhD student in Kanso's lab at USC, put the squid under a microscope and then exposed it to water containing Vibrio Fischeri bacteria. The process mimicked what happens in nature: the bacteria ended up in the correct spot within the squids' light organs.

To determine if cilia were passive or active within this process, the researchers needed to understand if the bacteria swam into the ink sack or in fact were helped by other structures and processes within the squid host. The researchers then repeated the same experiment without live bacteria--but with particles of the same size as the bacteria, namely one micron in diameter. What they found was that the particles accumulated in the same spot--demonstrating that a physical mechanism in the host (the squid) was at play.

The second phase of experiment then included larger particles (about 4 microns). One might have presumed that the larger particles would have a greater probability of contact with the light organ--but they didn't. This indicated that direct interception was not the dominant mechanism for particle capture and that some other factor was at play. The researchers set out to examine the role of the fluid flow generated by the cilia in filtering particles.

Upon further investigation, Kanso and Nawroth discovered that a vortical or "donut-like" flow generated by the cilia was kicking away most particles. The role of the fluid motion in filtering particles by size was verified using a physics-based mathematical model developed by Kanso and Guo. Kanso describes the role that cilia seemed to be playing as a "mechanical gate."

The researchers then mapped out the ciliated surface of the whole light organ and the flow field it generates. One of the core findings was that there were two distinct flows taking place by two different types of cilia. Longer cilia move in a "wave-like" fashion which creates a vortical flow field that filters particles and then shorter cilia which beat randomly keep the particles in place and gently mix the local flow. This random motion by the cilia and fluid mixing enhance the chemical screening of bacteria. To further prove the important role played by cilia, the researchers also found that if cilia are "killed," particles will accumulate everywhere in the organism.

Kanso and her collaborators are now developing a microfluidic platform to test the response of Vibrio Fischeri to distinct flow and chemical signals presented by the ciliated light organ of the host. This platform will be used as a research tool to investigate the relative importance of each of these signals in the recruitment of bacteria to ciliated surfaces.

Media Contact

Ian Chaffee
ichaffee@usc.edu
213-740-8606

 @USC

http://www.usc.edu 

Ian Chaffee | EurekAlert!

Further reports about: bacteria cilia symbiotic bacteria

More articles from Life Sciences:

nachricht Stiffness matters
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>