Scientists from California and Hong Kong genetically engineered bacterial cells so that they spontaneously grow in concentric rings. The number of rings can be controlled by altering expression of a single gene. They say the findings could shed light on the complex patterning that takes place during development.

"Natural systems make all kinds of wonderful patterns, but the problem is you never know what's really controlling it," said Terence Hwa, a professor of physics at the University of California, San Diego, and lead author on the study in a press release from the university. The research was published today in Science.

To create the bulls eye, researchers added genetic modules that sense how crowded the cells' environment has become and respond by altering the bacterial cells' movements.

One of the modules secretes a chemical signal called acyl-homoserine lactone (AHL). As the bacterial colony grows, AHL floods the accumulating cells, causing them to tumble in place rather than swim. Stuck in the agar of their dish, they pile up.

Because AHL doesn't diffuse very far, a few cells escape and swim away to begin the process again.

Left to grow overnight, the cells create a target-like pattern of concentric rings of crowded and dispersed bacterial cells. By tweaking just one gene that limits how fast and far cells can swim, the researchers were able to control the number of rings the bacteria made. They can also manipulate the pattern by modifying how long AHL lasts before it degrades.

Some Japanese people are endowed with a unique power to digest carbohydrates in seaweed, thanks to their gut microbes. The accidental finding--French scientists were studying enzymes that digest red algae when a genetic database revealed that the same gene could be found in some humans--hints at regional differences in our intestinal bacteria that may have allowed different groups to adapt to their local diets. And it's just the latest example of nutritional advantages derived from microbes, which give us the ability to digest foods whose nutrients would otherwise be lost to us and make essential vitamins and amino acids that our bodies can't.

As I wrote in a feature on our microbial menagerie in 2008,

New ultrafast DNA-sequencing technologies allow scientists to study the genetic makeup of entire microbial communities, each of which may contain hundreds or thousands of different species. For the first time, microbiologists can compare genetic snapshots of all the microbes inhabiting people who differ by age, origin, and health status. By analyzing the functions of those microbes' genes, they can figure out the main roles the organisms play in our bodies.

In the new study, published today in the journal Nature, researchers searched for the gene within bacteria living in the guts from 18 North Americans and from 13 Japanese. They found it in 5 of the Japanese but none of the Americans. The gene was probably transferred to human gut microbes when people ate seaweed--and the microbes that live on it. According to a piece in Nature,

Although gene transfer to gut microbes is suspected in other cases, this is the first clear-cut example in which a gut microbe has gained a new biological niche by snatching genes from an ingested bacterium, says Mirjam Czjzek, a chemist at the Pierre and Marie Curie University in Paris, one of the two researchers who led the study. "Probably there are many more examples," she says. "It's only because of this exotic niche and the very rare specificity of this enzyme that we were able to pinpoint where it came from."

As our food becomes increasingly sterile, our exposure to this genetic treasure chest is dwindling, Justin L. Sonnenburg, a Stanford University microbiologist told the journal. "We've gone to great lengths in the developed world to decrease the microbial burden of food, and in doing so we have decreased food-borne illness," says Sonnenburg, who wrote a commentary in Nature accompanying the study. "This is good, but it comes at a cost. We've eradicated this potentially beneficial microbial component."

Researchers at the Lawrence Berkeley National Laboratory have used advanced imaging techniques to solve the structure of one of nature's most important molecular machines. A clearer picture of this motor-like protein, which spins along strands of bacterial messenger RNA to read and translate it into proteins, may help pharmaceutical researchers develop new antibiotics. The researchers studied a version of the protein called Rho from E. coli bacteria. This type of protein, called a transcription factor, is also important in human development and disease.

In the video below, Rho, which is shaped like a hexagon with a hole in the center, is shown in cross section as it walks along the RNA strand, shown in orange. Rho spirals in such a way that it can only move in one direction along the RNA strand, which is crucial to making proteins properly.

In order to get a better picture of Rho, the Berkeley researchers used the lab's Advanced Light Source, which accelerates electrons to very high energies in order to create some of the brightest x-rays in the world. Using these x-rays, they were able to see a part of Rho's structure that was previously not very well understood.