miércoles, 9 de enero de 2013

Small, Small World


They’re invisible. They’re everywhere. And they rule.

 

 

By Nathan Wolfe
Photograph by Martin Oeggerli, with support from School of Life Sciences, FHNW

Breathe in. Feel the air pass through your nostrils and move into your nose. Your diaphragm contracts, pulling the air deep into your chest. Oxygen floods into tiny cavities in your lungs and travels into your capillaries, ready to fuel every cell in your body. You’re alive.

So is that breath you just took. When we inhale, our nostrils capture millions of invisible particles: dust, pollen, sea spray, volcanic ash, plant spores. These specks in turn host a teeming community of bacteria and viruses. A few types may trigger allergies or asthma. Far more rare are inhaled pathogens that are themselves the agents of diseases, such as SARS, tuberculosis, and influenza.

So is that breath you just took. When we inhale, our nostrils capture millions of invisible particles: dust, pollen, sea spray, volcanic ash, plant spores. These specks in turn host a teeming community of bacteria and viruses. A few types may trigger allergies or asthma. Far more rare are inhaled pathogens that are themselves the agents of diseases, such as SARS, tuberculosis, and influenza.

Over the past 15 years I’ve spent a lot of time poking cotton swabs up human noses, pig snouts, bird beaks, and primate proboscises, looking for signs of such agents before they cause deadly pandemics. As a result, I’ve come to think of air as the medium for the next pandemic rather than the means to sustain life. But breathe easy: Most of the microbes in the air do us little or no harm, and some almost certainly do us good. The truth is, we still understand precious little about them.



STREPTOCOCCUS
A colorized electron microscope image captures delicate chains of streptococcus in a laboratory sample. Though some strep infections can be deadly, many strains are harmless—among the thousands of benign beings that make their home in our bodies.
www.micronaut.ch


Photograph by Department of Microbiology, Biozentrum, University of Basel/Photo Researchers, Inc
All Images Colorized
BACTERIOPHAGE
These bacteria-infecting viruses, phages for short, are the most abundant life-form on the planet, their number far exceeding that of stars in the universe. Trillions inhabit each of us.



CAULOBACTER
The common waterborne bacterium Caulobacter crescentus reproduces asymmetrically. When a cell divides, one of its daughter cells is a free-swimming “swarmer,” powered by a hairlike flagellum. The other, “stalk” daughter cell is immobile, anchoring itself to a surface with one of nature’s strongest glues, resisting five tons of force per square inch


Photograph by Dennis Kunkel Microscopy, Inc
PHAGES IN ACTION
Bacteriophages escape from a dying streptococcus bacterium, ready to find another victim. Their ability to infect and kill specific strains may lead to new treatments for antibiotic-resistant bacteria.


INTESTINAL BACTERIA
The human gut teems with bacteria, many of their species still unknown. They help us digest food and absorb nutrients, and they play a part in protecting our intestinal walls. Gut bacteria may also help regulate weight and ward off autoimmune diseases.


HELICOBACTER
Helicobacter pylori (yellow), a common bacterium that lives in the stomach lining, increases the risk of stomach cancer (brown cells) and peptic ulcers. But over time H. pylori can reduce stomach acid and acid reflux, which may help fend off esophageal cancer. The microbe also appears to help protect us from allergies and asthma. Some scientists suspect that the dramatic increase in those conditions in the industrialized world could be related to the decreasing frequency of H. pylori in our stomachs, which is partly due to high doses of antibiotics in childhood.


Photograph by Eshel Ben-Jacob and Inna Brainis
PAENIBACILLUS
A lab-grown colony of Paenibacillus vortex organizes into a fanlike pattern, with arms reaching out to scout for food. Bacteria can act collectively, communicating with chemical signals.


Photograph by Steve Gschmeissner, Photo Researchers, Inc
CYANOBACTERIA
Tiny green cyanobacteria played an outsize role in Earth’s history by creating the planet’s oxygen-rich atmosphere through photosynthesis. Ancestral forms also evolved into chloroplasts, the cell parts that carry out photosynthesis in plants.


MOUTH MICROBES
The human mouth hosts a panoply of microbes, some taking up residence on the mouth lining (blue) within days after birth. Harmful species form biofilms, like the plaque that encourages tooth decay, or colonize the crevices between teeth and gums, causing periodontal disease. Oral probiotics designed to boost the population of species that outcompete pathogenic ones could help prevent or reverse dental disease.


STAPHYLOCOCCUS AUREUS
The bug lives harmlessly in the noses of about a third of us. But it can turn rogue, causing skin infections—or worse. Heavy use of antibiotics since the middle of the last century has prompted the evolution of deadly superbug strains.
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