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Gizmorama - November 1, 2017

Good Morning,


A new study has uncovered the details of bacteria's "sense of touch". So apparently microorganisms' have the touch.

Learn about this and more interesting stories from the scientific community in today's issue.

Until Next Time,
Erin


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*-- New study details bacteria's 'sense of touch' --*

How do bacteria sense and grab hold of surfaces, allowing biofilms to fester in hospitals and clog up sewer pipes? A new study detailing microorganisms' "sense of touch" has offered some answers.

Scientists first observed a bacterium cell's feelers, or pili, hair-like appendages that sense the cell's surroundings, using targeted fluorescent dye delivered by tiny maleimide molecules. The dyes allowed researchers to watch the movement of pili under a high-powered microscope.

Researchers were able to make the pili appear larger and fluoresce by substituting the chain up amino acids that normally make up the cell's appendages with an amino acid called a cysteine. The dyes bind easily with cysteine, enhancing the appendages visibility under the microscope.

"It's like switching on a light in a dark room," Courtney Ellison, a doctoral student at Indiana University, said in a news release. "Pili are composed of thousands of protein subunits called pilins, with each protein in the chain composed of amino acids arranged like a tangled mess of burnt-out Christmas lights. Swapping out a single light can illuminate the whole string."

To better understand how bacteria grab onto surfaces and create a biofilm, scientists tricked cells into thinking they were sensing a surface. They did so by using a large maleimide molecule to block the movement of the cell's pili.

Pili can extend and retract through the cell wall to "feel" around for nearby objects. The maleimide molecule effectively blocked the pili's ability to extend and move, tricking the cell into thinking it had bumped up against a surface.

"It's like trying to pull a rope with a knot in the middle through a hole -- the maleimide molecule can't pass through the hole the cell uses to extend and retract the pili," Ellison said.

The experiment -- detailed in a new paper published this week in the journal Science -- confirmed that a cell becomes aware of a surface when the pili's movement is restricted.

"These results told us the bacteria sense the surface like how a fisherman knows their line is stuck under water," said Yves Brun, professor of biology at IU. "It's only when they reel in the line that they sense a tension, which tells them their line is caught. The bacteria's pili are their fishing lines."

Biofilms can thwart valuable infrastructure and cause deadly infections, but researchers hope their new research will help scientists develop new ways to thwart their formation and growth.

"The more we understand about the mechanics of pili in biofilm formation and virulence, the more we can manipulate the process to prevent harm to people and property," Brun said.



*-- New technology can weigh single cells, measure mass fluctuation in real time --*

Scientists in Switzerland have developed a scale capable of weighing a single living cell. The device can even calculate changes in a cell's weight in real time -- with precision to milliseconds and trillionths of a gram.

The scale was designed by scientists at the Swiss Federal Institute of Technology in Zurich, or ETH Zurich. The device's arm features a transparent silicon cantilever. The wafer-thin plate is coated with a film of collagen or fibronectin. To weigh a cell, scientists lower the cantilever in a cell culture chamber where it presses against the cell and picks it up.

"The cell hangs on the underside of a tiny cantilever for the measurements," doctoral student Gotthold Fläschner, who helped design the scale, said in a news release.

At the opposite end of the device's arm is a pulsing blue laser, which causes the nanoscale cantilever to oscillate. A second infrared laser measures the oscillation before and after the cell is affixed to the plate.

"The cell's mass can be calculated from the difference between the two oscillations," said researcher David Martínez-Martín, who invented the device.

The technology feeds real-time measurements to a computer screen. A cell's mass fluctuations can be tracked for several hours or even days.

The scale can be installed on the object plate of a high-performance fluorescence microscope, allowing scientists to observe biochemical process inside the cell while monitoring changes in the cell's weight.

Early tests using the scale has already begun to offer insights.

"We established that the weight of living cells fluctuates continuously by about one to four percent as they regulate their total weight," said Martínez-Martín.

The fluctuation in weight only ceases after the cell dies.

"We're seeing things that nobody else has yet observed," Fläschner said.

Researchers described their new technology in a paper published this week in the journal Nature.

Scientists expect the new technology to be used to study a variety of cellular processes. The device could be used to analyze a pathological mechanisms inside a diseased cell or observe the effects of a new drug.

"A cell's mass is a very good indicator of its physiology," said Martínez-Martín.

The patented scale -- which could also be used by material scientists to measure nanoparticles -- will soon by manufactured by Swiss company Nanosurf AG.

***

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