About 20 percent of the chronic carriers of the virus will go on to develop more serious liver disease, including cirrhosis and cancer. That means that any research on how the virus replicates in cells is incredibly difficult. But Lai and his research group have managed to study the function of some of the viral genes. They have discovered that one of the hepatitis C viral proteins binds to a few key players in the human immune system, members of the tumor necrosis factor TNF receptor family.
It may also explain how the virus damages the liver and causes hepatitis. He hopes his research will lead to new ways to treat people already infected with hepatitis C, so that doctors can stop the virus before it causes serious liver disease.
Part of this comes from the ability of viruses to shuffle genes with as much deft as some genetic engineers. That means that evolution occurs all the time in viruses. More stories about: Research. The USC study also underscored a major problem facing cancer researchers: studying non-representative samples of patient cells.
Department of State. USC Annenberg, PR firm Golin and Zignal Labs reveal the first data science-based polarization index to provide a roadmap for business leaders to navigate controversial issues. Moreover, slime molds have evolved a system for essentially mapping their terrain and memorizing where not to go: As they move, they leave a translucent chemical trail behind that tells them which areas are not worth revisiting. After Physarum explores an area and finds it lacking in nutrients, it leaves behind a chemical trail as a kind of externalized memory that tells the slime mold not to go back there.
When bacteria were first observed through a microscope, suspended in liquid on slides, in their simplicity they seemed like the archetypes of primitive, solitary cells. The truth, however, is that in the wild, most bacteria are highly gregarious. Some bacteria do swim through their environment as lonely individuals but most bacterial cells — and most species of bacteria — prefer to live in compact societies called biofilms anchored to surfaces. The individual swimmers often represent offshoots of biofilms, seeking to colonize new locations.
In a high-magnification scanning electron micrograph of a Pseudomonas aeruginosa biofilm, the individual rod-shaped bacteria are interlinked by hairlike structures called pili.
Bacillus bacteria secrete an extracellular matrix that encases the cells and helps them form a more structured community. Moreover, biofilms are not just dense accumulations of bacterial cells. The biofilm is stained with Congo red dye, which bonds to the extracellular matrix proteins that the bacteria secrete as a scaffolding for their community. The deeply wrinkled surface of the biofilm maximizes the area through which the bacteria can absorb oxygen; it also probably helps them collect nutrients and release waste products efficiently.
As this Pseudomonas biofilm expands, it develops a more complex internal structure. Bacteria in different parts of its mass may also develop more specialized functions. Within the biofilm, the bacteria divide the labor of maintaining the colony and differentiate into forms specialized for their function. In this biofilm of the common soil bacterium Bacillus subtilis , for example, some cells secrete extracellular matrix and anchor in place, while some stay motile; cells at the edges of the biofilm may divide for growth, while others in the middle release spores for surviving tough conditions and colonizing new locations.
The wrinkled structure of this Bacillus subtilis biofilm helps to ensure that all the bacteria in it have access to oxygen left. A digital scanned model of the biofilm helps illustrate how the bacterial community can vary its structure in three dimensions right.
One might wonder why natural selection would have favored this collective behavior instead of more rampant individualism among the cells. But it may also be that every role within the biofilm has its advantages: Cells at the edge are most exposed to dangers and must reproduce furiously to expand the biofilm, but they also have access to the most nutrients and oxygen.
Cells on the inside depend on others for their vital rations but they may survive longer. The surfaces that biofilms grow across are not always solid. These B.
The genetic pathways involved in forming a pellicle are essentially the same as those used in growing across stones, though they may respond to the changes in their habitat by altering the precise mix of proteins in the extracellular matrix as needed. Bacteria can grow across nonsolid surfaces, too, as this B.
Expansive growth is not the only way in which microbial communities can move. Below, B. Biofilms swarm when they detect that they are in environments rich in nutrients: Swarming helps a biofilm exploit this valuable territory before any competing communities can.
At least two important changes in the differentiation of the cells in a biofilm take place to enable swarming. First, motile cells on the periphery of the film develop extra flagellae, which enables them to swim more energetically. Second, some edge cells also begin to secrete surfactant, a slippery material that helps the motile cells slide more rapidly over the surface. When biofilms grow in flat laboratory dishes, the dendritic columns of swarming biofilms remain neatly distinct: They extend and coil in and around one another but they do not cross.
That seems to be in part because the surfactant piles up around the biofilm branches as a barrier. Note: Content may be edited for style and length. Science News. ScienceDaily, 25 May American Society for Microbiology. Can bacteria make you smarter?. Retrieved November 11, from www. Scientists have completed a computational modeling study that suggests our experience and
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