A drug's life in the body. Medicines taken by mouth pass through the liver before they are absorbed into the bloodstream. Other forms of drug administration bypass the liver, entering the blood directly. See 2528 for a labeled version of this illustration. Featured in Medicines By Design.

Colonies of bacteria growing despite high concentrations of antibiotics. These colonies are visible both by eye, as seen on the left, and by bioluminescence imaging, as seen on the right. The bioluminescent color indicates the metabolic activity of these bacteria, with their red centers indicating high metabolism.

More information about the research that produced this image can be found in the Antimicrobial Agents and Chemotherapy paper “Novel aminoglycoside-tolerant phoenix colony variants of Pseudomonas aeruginosa” by Sindeldecker et al.

Kinases are enzymes that add phosphate groups (red-yellow structures) to proteins (green), assigning the proteins a code. In this reaction, an intermediate molecule called ATP (adenosine triphosphate) donates a phosphate group from itself, becoming ADP (adenosine diphosphate). See image 2534 for an unlabeled version of this illustration. Featured in Medicines By Design.

A model of the molecule himastatin, which was first isolated from the bacterium Streptomyces himastatinicus. Himastatin shows antibiotic activity. The researchers who created this image developed a new, more concise way to synthesize himastatin so it can be studied more easily.

More information about the research that produced this image can be found in the Science paper “Total synthesis of himastatin” by D’Angelo et al.

Related to image 6850 and video 6851.

T cells are white blood cells that are important in defending the body against bacteria, viruses and other pathogens. Each T cell carries proteins, called T-cell receptors, on its surface that are activated when they come in contact with an invader. This activation sets in motion a cascade of biochemical changes inside the T cell to mount a defense against the invasion. Scientists have been interested for some time what happens after a T-cell receptor is activated. One obstacle has been to study how this signaling cascade, or pathway, proceeds inside T cells.

In this image, researchers have created a T-cell receptor pathway consisting of 12 proteins outside the cell on an artificial membrane. The image shows two key steps during the signaling process: clustering of a protein called linker for activation of T cells (LAT) (blue) and polymerization of the cytoskeleton protein actin (red). The findings show that the T-cell receptor signaling proteins self-organize into separate physical and biochemical compartments. This new system of studying molecular pathways outside the cells will enable scientists to better understand how the immune system combats microbes or other agents that cause infection.

To learn more how researchers assembled this T-cell receptor pathway, see this press release from HHMI's Marine Biological Laboratory Whitman Center. Related to video 3786.

An image of the area of the mouse brain that serves as the 'master clock,' which houses the brain's time-keeping neurons. The nuclei of the clock cells are shown in blue. A small molecule called VIP, shown in green, enables neurons in the central clock in the mammalian brain to synchronize.