Featured Research

from universities, journals, and other organizations

Tracking A Microscopic "Rocket" By Its Tail: Laser Device Lets Researchers See How Bacteria Spread Between Cells

Date:
November 2, 2000
Source:
Johns Hopkins University
Summary:
Using a laser device that allows them to view microscopic movement, biomedical engineering researchers at The Johns Hopkins University have produced startling new findings about how deadly bacteria spread infection between neighboring cells.

Using a laser device that allows them to view microscopic movement, biomedical engineering researchers at The Johns Hopkins University have produced startling new findings about how deadly bacteria spread infection between neighboring cells.

Related Articles


Writing in the October 26 issue of Nature, Scot C. Kuo and James L. McGrath describe how Listeria monocytogenes, a common source of poisoning in processed foods, exhibit an unusual stutter-step motion while building rocketlike "tails" that propel them from one living host cell to another. The engineers' discovery contradicts a widely held belief that filaments in these tails grow and push in a smooth continuous motion.

To study the rocketlike motion of Listeria, the researchers used an innovative tracking device developed by Kuo. The instrument -- a laser built into an optical microscope -- allowed them to peer inside living cells and record the motion of Listeria microbes, the potentially fatal pathogens that have triggered a number of major processed food recalls in recent years.

Scientists already knew that Listeria evade detection by white blood cells -- the body's key defense system -- by hiding inside living intestinal cells. Inside each host cell, the pathogen feeds and multiplies until it causes the cell to burst and die. But before this happens, the bacteria causes molecules of a protein called actin to assemble into filaments to form rocketlike tails that can "thrust" bacteria from the infected cell toward a healthy neighboring cell. Scientists know that these filaments grow only near the bacterium but disassemble throughout the tail. The balance of growth and disassembly gives the appear of a rocket "plume" of constant length.

Prior to beginning their project, Kuo and McGrath expected to confirm a theory that filament growth nudges a bacterium toward its next target in a smooth, continuous manner. Instead, Kuo and McGrath detected a series of steplike motions along the filaments. "We shouldn't have seen that. The fact that we can see these step-like motions means that the existing theories are missing a really fundamental feature," says Kuo, an assistant professor in the Johns Hopkins Department of Biomedical Engineering. His co-author, McGrath, is a postdoctoral fellow in his laboratory.

"Each bacterium is not just ‘surfing' ahead of these tails as the filaments grow within the infected host cell," says Kuo. "Instead, the bacteria appear to hold onto some of these strands to control the locomotion process as new protein building blocks are incorporated into the tails. The step-like motion we observed could correspond to each addition of a building block."

The molecular-scale steps of Listeria are reminiscent of "motor" proteins, which haul "cargo" by a walking motion within cells. "Our data are the first indication that Listeria might use molecular motors," Kuo says.

Although their experiments focused on Listeria, Kuo and McGrath believe their findings could also shed light on the movement of related pathogens that cause ailments such as Rocky Mountain spotted fever, Shigella and vaccinia virus (a relative of smallpox).

Learning how these bacteria make use of their microscopic tails may not immediately lead to new treatments for these infections. But Kuo says these findings "add significantly to our basic understanding of how cells crawl and control their shape."


Story Source:

The above story is based on materials provided by Johns Hopkins University. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins University. "Tracking A Microscopic "Rocket" By Its Tail: Laser Device Lets Researchers See How Bacteria Spread Between Cells." ScienceDaily. ScienceDaily, 2 November 2000. <www.sciencedaily.com/releases/2000/11/001101075017.htm>.
Johns Hopkins University. (2000, November 2). Tracking A Microscopic "Rocket" By Its Tail: Laser Device Lets Researchers See How Bacteria Spread Between Cells. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2000/11/001101075017.htm
Johns Hopkins University. "Tracking A Microscopic "Rocket" By Its Tail: Laser Device Lets Researchers See How Bacteria Spread Between Cells." ScienceDaily. www.sciencedaily.com/releases/2000/11/001101075017.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Winter Can Cause Depression — Here's How To Combat It

Winter Can Cause Depression — Here's How To Combat It

Newsy (Nov. 23, 2014) Millions of American suffer from seasonal depression every year. It can lead to adverse health effects, but there are ways to ease symptoms. Video provided by Newsy
Powered by NewsLook.com
Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
Don't Fall For Flu Shot Myths

Don't Fall For Flu Shot Myths

Newsy (Nov. 23, 2014) Misconceptions abound when it comes to your annual flu shot. Medical experts say most people older than 6 months should get the shot. Video provided by Newsy
Powered by NewsLook.com
Indians Muck in for Cleaner Communities

Indians Muck in for Cleaner Communities

AFP (Nov. 22, 2014) India's government is urging all citizens to come together in a mass movement to clean the nation -- but will people heed the call? Duration: 02:39 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins