Dear Docs, Medicos and friends of Science and
Genetics,

Though Space flight experiment shows the surprising result, the reason may be
either 0 gravity or the 100+ radiation exposure. But more likely the radiation
part to change the ionic concentration which favors the bacterial to increase
bacterial virulence and /or kick of the multiplication of the bacterium due to
higher radiation exposure in the space.

Salmonella Spills
its Secrets on the Space Shuttle















May
6, 2009: Salmonella, what's gotten into
you?

Researchers
have been asking themselves this question ever since
Salmonella
bacteria grown on board the space shuttle returned to Earth
3 to 7 times more virulent than Salmonella grown
on the ground under otherwise identical conditions. Figuring
out why could help safeguard astronauts from disease and
lead
to new treatments for food poisoning and other common
ailments
on Earth.

New
research by Cheryl Nickerson (Arizona State University) and
colleagues explains not only why Salmonella gets
"revved up" in space, but also how to calm it down
again.

"We
think space travel tricks Salmonella into behaving
as if it is in the human gut," Nickerson says. "It's
a mechanical phenomenon having to do with 'fluid shear.'"

Right:
A photomicrograph of Salmonella bacteria. Courtesy of
Pacific
Northwest National Laboratory. [Larger
image]
Salmonella
microbes have the ability to sense the force of fluid moving
past their outer surfaces. This "fluid shear" acts
as a signal to the microbe, helping it to know where in the
human body it's located. Salmonella usually enters
the body by hitching a ride on food that a person eats. In
the middle of the tube-shaped intestines, the liquid-like
mixture of half-digested food and digestive juices churns
around quite a bit, so the amount of fluid shear is high.

But
as a Salmonella cell approaches the wall of the intestines,
it slips into the tiny spaces between microscopic, hair-like
protrusions called microvilli that cover the intestinal
lining.
There, the cell becomes sheltered from the churning motion,
and fluid shear drops to very low levels. And it's there
that
the bacterial cell can cross from the intestines into the
bloodstream to start an infection. So
it would make sense for a bacterium experiencing low fluid
shear to alter the activity of genes that help the bacterium
survive and cause infection.
Computer-based
simulations have shown that the amount of fluid shear
experienced
by bacteria in the weightless environment of orbit is
similar
to the amount in these tiny spaces at the intestinal wall,
Nickerson says. "Space flight is a low fluid shear
environment."


Nickerson's
team looked at Salmonella from two shuttle flights
to the International Space Station: STS-115 in Sept. 2006
and STS-123 in March 2008. They found that 167 genes were
either more or less active in these keyed-up bacteria than
in the bacteria that hadn't flown. The team also identified
a "master switch" that regulates about one-third
of these genes, a protein called Hfq. Activity of this
protein
was also affected by the low fluid shear conditions of
spaceflight.

Now
that scientists know which genes and proteins help create
this virulence-boosting effect, they are working to use this
information to develop new strategies to combat Salmonella
food-borne illness, such as vaccines and therapeutics.

The
team has already found one promising way to combat
Salmonella's
extra virulence: add a dash of ions. When Nickerson and her
colleagues grew the same strain of bacteria in a culture
medium
that contained higher concentrations of five ions --
potassium,
chloride, sulfate, magnesium, and phosphate -- the virulence
of the bacteria due to spaceflight no longer went up!

"Cells
are funny things," Nickerson says. "If you give
them too much or too little of something they're used to
having
around, they'll surprise you with how they respond."

As
it turns out, many of the genes activated by the low fluid
shear environment of spaceflight are involved in
transporting
these ions in and out of the cells, so there could be a
connection.
Research on this ion effect is still ongoing, Nickerson
says,
but she speculates that it could eventually lead to new ways
to use these ions to ward off Salmonella infections.

"One
question people ask me is, 'Why in the world did you think
of looking at [Salmonella in space]?' I turn that
around and ask, 'Why would you not think of it!'" Nickerson
says. "Whenever scientists have studied microbes under
extreme conditions, we have found amazing new insights into
how they function. Space flight is another extreme
environment
that's relatively untapped."

Forwarded By yours Dr.BHUDIA-Science Group
Of INDIA.
http://uk.groups.yahoo.com/group/venustransit_2004/
President:"Kutch
Science Foundation".
Founder
:"Kutch
Amateurs Astronomers Club - Bhuj - Kutch"
,
http://uk.geocities.com/wildlifeofkutch/
http://in.groups.yahoo.com/group/scienceclubofindia
http://in.groups.yahoo.com/group/kutchscience
http://in.groups.yahoo.com/group/kachchh
http://in.groups.yahoo.com/group/bhuj
Do visit our ABOVE Clubs/Groups of Science club of
India, Science Group of
India.

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