bodies are teeming with billions of bacteria. While some may cause disease,
most are innocuous. A new study sheds light on how we communicate with these
friendly bacteria. Eric Libby reports.
McFall-Ngai researches how benign bacteria affect us at the genetic level. The
University of Wisconsin developmental biologist says that there are unique
communities of health-promoting bacteria in many tissues including the skin,
nasal passages, eyeballs, and our digestive systems.
these bacteria can even leave us prone to diseases. McFall-Nigh notes, for
example, that a woman's vagina normally hosts hundreds of types of bacteria.
After a treatment of antibiotics, she says, yeast infections are more likely.
So there are all these different areas of the human body that require, for
their health, interactions with communities of co-evolved microbes.
points out that most of our bacterial associates cannot be grown in a lab.
Furthermore, determining how any single species of bacteria affects us is
difficult. So McFall-Ngai studies a simpler system: an animal which has a
special relationship with just one type of bacteria… the Hawaiian bobtail squid
and the bacteria Vibrio fischeri.
tiny bobtail squid has a head about three centimeters long and feeds on shrimp
in shallow coastal waters. Its bacterial partner, Vibrio fischeri, lives
inside the squid and receives nutrients. In exchange for the food, the bacteria
produce light. The squid usually hunts at night and without any camouflage it
would cast a shadow. Instead, the squid
uses the bacteria to emit light of the same intensity and color as down-glowing
moonlight and starlight and avoids detection from below.
the squid and the bacteria can be grown in the lab independently. When they
partner up, the bacteria cause the squid cells to change which of their genes
are active. Many of these altered genes are also present in mice and humans.
Some of them act in the immune response against pathogens.
compares these bacteria-induced genetic changes to a language and says it
doesn't seem to matter whether the bacteria inducing those changes are
disease-causing or health-promoting. Although the same language appears to be
used, it's the difference between an argument and a civil conversation.
the language our bodies use to communicate with bacteria is important to
improving medical treatment. Current antibiotics often kill both the bad and
the good bacteria, leaving room for opportunistic pathogens to colonize. So, if
we want better treatments against our foes, we need to learn how we talk to our