The tiny water bacterium Caulobacter crescentus secretes a sugary substance so sticky that just a tiny bit could hold several cars together. First, it attaches to a surface at the end of its cell body, which has a propeller-like flagellum. On contact, the flagellum stops moving with help from nearby cable-like structures called pili. This arrest stimulates production of the sugary adhesive, which then is released at the attachment site and immediately binds the cell to the surface. Since binding helps some bacteria form slimy residues and hard-to-treat infections, knowing how this occurs could help us better understand how to treat and prevent such outcomes.

While HIV has only a handful of proteins of its own, a new study shows that the virus makes the most of its small repertoire. Researchers used a comprehensive approach to uncover nearly 500 interactions between HIV and human proteins. The study has produced one of the most detailed surveys to date of how HIV interacts with human cells. Most of these interactions were previously unknown, opening up a vast new territory of potential drug targets for treating people infected with HIV.

A factory�s assembly line goes haywire, and products in various stages of completion spill out until the line shuts down. When cells, most of which are constantly making proteins, face this challenge, they have two choices: slow down production or, if the situation is bad enough, commit suicide. Cells decide using a tightly controlled process that involves the nasty-smelling molecule hydrogen sulfide (H₂S). Better known as an explosive, highly toxic gas that reeks like rotten eggs, H₂S might help researchers understand diseases linked to excess cellular suicide like Alzheimer�s and Parkinson�s.

The fluoride in toothpaste and tap water helps protect teeth from cavity-causing bacteria. Scientists recently learned about the events that happen when bacteria come into contact with fluoride. By mixing bacterial RNA with a variety of chemicals in a test tube, scientists discovered a group of riboswitches (sections of RNA) in bacteria that bind to fluoride. When this occurs, the fluoride-sensing riboswitch activates genes coding for ion channels that pump fluoride back out of the cell. The finding may help scientists increase the potency of fluoride and make it more toxic to bacteria.

Many of the proteins that control cell division appear for a single step of the process and then vanish until the next round of division. A team of researchers working in yeast has now discovered how certain transient proteins are marked for destruction. As soon as they�re made, the messenger RNA molecules that serve as the proteins� blueprints get tagged with a special protein. These tagged mRNAs later degrade in response to a cellular signal, triggering the disappearance of the proteins they encode. This work offers new insights into how cells control division and may lead to new ways to combat the runaway cell division that characterizes cancer.

This time of year, to many people, blinking lights and stress mean the holidays are upon us. But to scientists at Caltech, they reveal a new understanding of how bacteria respond—at the genetic level—to a certain type of stress. To track this response, scientists studied the sigma B protein in bacterial cells. When triggered by extreme temperature, starvation or other stressors, sigma B can activate more than 150 genes. The researchers inserted a fluorescent sensor into bacterial cells so that the cells would glow green when sigma B sprang into action. Then they doused the bacteria with a chemical stressor that essentially saps the cells� energy. As expected, sigma B flipped on. But then, just as quickly, it flipped off, even though the chemical remained in the environment. This on-off behavior, which appeared as a blinking green light, reveals that bacteria may “hedge their bets” when exposed to energy stress. Rather than dedicating all their resources for an extended period, the cells offer a brief, dramatic response, then return to their normal state, ready for a different environmental stressor. This could help bacterial populations survive in changing conditions. Because sigma B controls the disease-causing abilities of some bacteria, this research could help us better understand the genetics—and potential weaknesses—of organisms that cause a host of potentially deadly infections.

While some cells divide into copies to increase their numbers, others double their genetic material to increase their actual size. To better understand this process called endocycling, researchers studied fruit fly salivary gland cells, which endocycle about 10 times during the fly�s lifetime and increase in size by more than 1,000-fold. The scientists identified how specific proteins function as a molecular oscillator to drive the process. Since endocycling occurs in most plants and invertebrate animals, the findings could lead to improved agricultural methods. They also are relevant to human diseases that involve cells that endocycle, such as placental, heart, blood and liver cells.

Diffuse Large B-cell Lymphoma is the most common type of lymphoma in adults. It has been linked to an overabundance of BCL6—a protein that binds DNA and regulates gene activities, including genes that control B-cell differentiation. Researchers have now uncovered one reason for the excess. A protein called FBXO11 normally helps keep BCL6 levels low by targeting it for degradation. But when the FBXO11 gene is mutated or deleted, BCL6 levels rise and cells can turn malignant. The discovery of FBXO11�s role offers a promising new therapeutic target for treating the disease.

For more than 70 years, doctors have relied on a class of drugs called heparins to decrease the risk of blood clots in their patients. But heparins, which are made of carbohydrate subunits, are tricky to manufacture. Synthesis of one version of the drug requires 50 steps and generates large quantities of hazardous waste. A new method that uses a combination of chemical and enzymatic processes enables drug production in just 10 or 12 steps. This more efficient approach is expected to significantly reduce the cost of the medicine and may even be adapted to the synthesis of other drugs.

In response to a cut or other wound, the human body produces its own hydrogen peroxide to ward off infection and start the healing process. Scientists found that such wound-induced hydrogen peroxide triggers a protein, called Lyn, that routes white blood cells and immune cells down a particular cellular pathway. While this process is ideal for healing infections, it can stimulate tumor growth and cause inflammation. By blocking Lyn, researchers reduced the recruitment of white blood cells to wounds. The finding could provide a better understanding of cancer and wound healing.