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.

Industrious V. cholerae bacteria (yellow) tend to thrive in denser biofilms (left) while moochers (red) thrive in weaker biofilms (right). More information about the research behind this image can be found in a Biomedical Beat Blog posting from February 2014.

Viral RNA (red) in an RSV-infected cell. More information about the research behind this image can be found in a Biomedical Beat Blog posting from January 2014.

The nucleus of a human fibroblast cell with chromatin—a substance made up of DNA and proteins—shown in various colors. Fibroblasts are one of the most common types of cells in mammalian connective tissue, and they play a key role in wound healing and tissue repair. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6888 and 6893.

The structure of a gene-regulating zinc finger protein bound to DNA.

Anaphase is the critical step during mitosis when sister chromosomes are disjoined and directed to opposite spindle poles, ensuring equal distribution of the genome during cell division. In this image, one pair of sister chromosomes at the top was lost and failed to divide after chemical inhibition of polo-like kinase 1. This image depicts chromosomes (blue) separating away from the spindle mid-zone (red). Kinetochores (green) highlight impaired movement of some chromosomes away from the mid-zone or the failure of sister chromatid separation (top). Scientists are interested in detailing the signaling events that are disrupted to produce this effect. The image is a volume projection of multiple deconvolved z-planes acquired with a Nikon widefield fluorescence microscope.

This image was chosen as a winner of the 2016 NIH-funded research image call. The research that led to this image was funded by NIGMS.

Related to image 5765.

These cells are induced stem cells made from human adult skin cells that were genetically reprogrammed to mimic embryonic stem cells. The induced stem cells were made potentially safer by removing the introduced genes and the viral vector used to ferry genes into the cells, a loop of DNA called a plasmid. The work was accomplished by geneticist Junying Yu in the laboratory of James Thomson, a University of Wisconsin-Madison School of Medicine and Public Health professor and the director of regenerative biology for the Morgridge Institute for Research.

The receptor is shown bound to an antagonist, ML056.

3D reconstructions of two stages in the assembly of the bacterial ribosome created from time-resolved cryo-electron microscopy images. Ribosomes translate genetic instructions into proteins.

Molecular biologists are increasingly relying on bioinformatics software to visualize molecular interaction networks and to integrate these networks with data such as gene expression profiles. Related to 2749.

Stereo triplet of a sea urchin embryo stained to reveal actin filaments (orange) and microtubules (blue). This image is part of a series of images: 1047, 1048, 1049, 1050 and 1052.

This network map shows the overlap (green) between the long QT syndrome (yellow) and epilepsy (blue) protein-interaction neighborhoods located within the human interactome. Researchers have learned to integrate genetic, cellular and clinical information to find out why certain medicines can trigger fatal heart arrhythmias. Featured in Computing Life magazine.

This wreath represents the molecular structure of a protein, Cas4, which is part of a system, known as CRISPR, that bacteria use to protect themselves against viral invaders. The green ribbons show the protein's structure, and the red balls show the location of iron and sulfur molecules important for the protein's function. Scientists harnessed Cas9, a different protein in the bacterial CRISPR system, to create a gene-editing tool known as CRISPR-Cas9. Using this tool, researchers are able to study a range of cellular processes and human diseases more easily, cheaply and precisely. In December, 2015, Science magazine recognized the CRISPR-Cas9 gene-editing tool as the "breakthrough of the year." Read more about Cas4 in the December 2015 Biomedical Beat post A Holiday-Themed Image Collection.

Under the microscope, an E. coli cell lights up like a fireball. Each bright dot marks a surface protein that tells the bacteria to move toward or away from nearby food and toxins. Using a new imaging technique, researchers can map the proteins one at a time and combine them into a single image. This lets them study patterns within and among protein clusters in bacterial cells, which don't have nuclei or organelles like plant and animal cells. Seeing how the proteins arrange themselves should help researchers better understand how cell signaling works.

Myelinated axons in a rat spinal root. Myelin is a type of fat that forms a sheath around and thus insulates the axon to protect it from losing the electrical current needed to transmit signals along the axon. The axoplasm inside the axon is shown in pink. Related to 3397.

Mosquito larvae with genes edited by CRISPR. This species of mosquito, Culex quinquefasciatus, can transmit West Nile virus, Japanese encephalitis virus, and avian malaria, among other diseases. The researchers who took this image developed a gene-editing toolkit for Culex quinquefasciatus that could ultimately help stop the mosquitoes from spreading pathogens. The work is described in the Nature Communications paper "Optimized CRISPR tools and site-directed transgenesis towards gene drive development in Culex quinquefasciatus mosquitoes" by Feng et al. Related to image 6769 and video 6771.

Planarians are freshwater flatworms that have powerful abilities to regenerate their bodies, which would seem to make them natural model organisms in which to study stem cells. But until recently, scientists had not been able to efficiently find the genes that regulate the planarian stem cell system. In this image, a single stem cell has given rise to a colony of stem cells in a planarian. Proliferating cells are red, and differentiating cells are blue. Quantitatively measuring the size and ratios of these two cell types provides a powerful framework for studying the roles of stem cell regulatory genes in planarians.

A crystal of pig trypsin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3744 and 3745.

This video condenses 6.5 minutes into less than a minute to show how the toxin in bee venom, called melittin, destroys an animal or bacterial cell. What looks like a red balloon is an artificial cell filled with red dye. Melittin molecules are colored green and float on the cell's surface like twigs on a pond. As melittin accumulates on the cell's membrane, the membrane expands to accommodate it. In the video, the membrane stretches into a column on the left. When melittin levels reach a critical threshold, countless pinhole leaks burst open in the membrane. The cell's vital fluids (red dye in the video) leak out through these pores. Within minutes, the cell collapses.

An anchor cell (red) pushes through the basement membrane (green) that surrounds it. Some cells are able to push through the tough basement barrier to carry out important tasks--and so can cancer cells, when they spread from one part of the body to another. No one has been able to recreate basement membranes in the lab and they're hard to study in humans, so Duke University researchers turned to the simple worm C. elegans. The researchers identified two molecules that help certain cells orient themselves toward and then punch through the worm's basement membrane. Studying these molecules and the genes that control them could deepen our understanding of cancer spread.

Multicellular yeast called snowflake yeast that researchers created through many generations of directed evolution from unicellular yeast. Stained cell membranes (green) and cell walls (red) reveal the connections between cells. Younger cells take up more cell membrane stain, while older cells take up more cell wall stain, leading to the color differences seen here. This image was captured using spinning disk confocal microscopy.

Related to images 6970 and 6971.

Sensory organs have cells equipped for detecting signals from the environment, such as odors. Receptors in the membranes of nerve cells in the nose bind to odor molecules, triggering a cascade of chemical reactions tranferred by G proteins into the cytoplasm.

Neurons (green) and glial cells from isolated dorsal root ganglia express COX-2 (red) after exposure to an inflammatory stimulus (cell nuclei are blue). Lawrence Marnett and colleagues have demonstrated that certain drugs selectively block COX-2 metabolism of endocannabinoids -- naturally occurring analgesic molecules -- in stimulated dorsal root ganglia. Featured in the October 20, 2011 issue of Biomedical Beat.

Stereo triplet of a sea urchin embryo stained to reveal actin filaments (orange) and microtubules (blue). This image is part of a series of images: image 1048, image 1049, image 1050, image 1051 and image 1052.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-out version 5769 of this illustration.

This image of a mammalian epithelial cell, captured in metaphase, was the winning image in the high- and super-resolution microscopy category of the 2012 GE Healthcare Life Sciences Cell Imaging Competition. The image shows microtubules (red), kinetochores (green) and DNA (blue). The DNA is fixed in the process of being moved along the microtubules that form the structure of the spindle.

The image was taken using the DeltaVision OMX imaging system, affectionately known as the "OMG" microscope, and was displayed on the NBC screen in New York's Times Square during the weekend of April 20-21, 2013. It was also part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

The extracellular matrix (ECM) is most prevalent in connective tissues but also is present between the stems (axons) of nerve cells, as shown here. Blue-colored nerve cell axons are surrounded by brown-colored, myelin-supplying Schwann cells, which act like insulation around an electrical wire to help speed the transmission of electric nerve impulses down the axon. The ECM is pale pink. The tiny brown spots within it are the collagen fibers that are part of the ECM.

Dengue virus is a mosquito-borne illness that infects millions of people in the tropics and subtropics each year. Like many viruses, dengue is enclosed by a protective membrane. The proteins that span this membrane play an important role in the life cycle of the virus. Scientists used cryo-EM to determine the structure of a dengue virus at a 3.5-angstrom resolution to reveal how the membrane proteins undergo major structural changes as the virus matures and infects a host. For more on cryo-EM see the blog post Cryo-Electron Microscopy Reveals Molecules in Ever Greater Detail. You can watch a rotating view of the dengue virus surface structure in video 3748.

Ionic and covalent bonds hold molecules, like sodium chloride and chlorine gas, together. Hydrogen bonds among molecules, notably involving water, also play an important role in biology. See image 2520 for a labeled version of this illustration. Featured in The Chemistry of Health.

This crystal structure shows a conserved hypothetical protein from Mycobacterium tuberculosis. Only 12 other proteins share its sequence homology, and none has a known function. This structure indicates the protein may play a role in metabolic pathways. Featured as one of the August 2007 Protein Structure Initiative Structures of the Month.

This network map shows molecular interactions (yellow) associated with a congenital condition that causes heart arrhythmias and the targets for drugs that alter these interactions (red and blue).

Analysis of 68 million-year-old collagen molecule fragments preserved in a T. rex femur confirmed what paleontologists have said for decades: Dinosaurs are close relatives of chickens, ostriches, and to a lesser extent, alligators. A Harvard University research team, including NIGMS-supported postdoctoral research fellow Chris Organ, used sophisticated statistical and computational tools to compare the ancient protein to ones from 21 living species. Because evolutionary processes produce similarities across species, the methods and results may help illuminate other areas of the evolutionary tree. Featured in the May 21, 2008 Biomedical Beat.

This scanning electron microscope (SEM) image shows podocytes--cells in the kidney that play a vital role in filtering waste from the bloodstream--from a patient with chronic kidney disease. This image first appeared in Princeton Journal Watch on October 4, 2013.

Body organs such as the liver and kidneys process chemicals and toxins. These "target" organs are susceptible to damage caused by these substances. See image 2497 for a labeled version of this illustration.

An atomic force microscopy image shows DNA folded into an intricate, computer-designed structure. The image is featured on Biomedical Beat blog post Cool Images: A Holiday-Themed Collection. For more background on DNA origami, see Cool Image: DNA Origami. See also related image 3690.

This illustration of an epoxide-opening cascade promoted by water emulates the proposed biosynthesis of some of the Red Tide toxins.

Luciferase-based imaging enables visualization and quantification of internal organs and transplanted cells in live adult zebrafish. In this image, a cardiac muscle-restricted promoter drives firefly luciferase expression (lateral view).
For imagery of both the lateral and overhead view go to 3556.
For imagery of the overhead view go to 3557.
For more information about the illumated area go to 3559.

Macrophages (green) are the professional eaters of our immune system. They are constantly surveilling our tissues for targets—such as bacteria, dead cells, or even cancer—and clearing them before they can cause harm. In this image, researchers were testing how macrophages responded to different molecules that were attached to silica beads (magenta) coated with a lipid bilayer to mimic a cell membrane.

Find more information on this image in the NIH Director’s Blog post "How to Feed a Macrophage."

Wound healing requires the action of stem cells. In mice that lack the Sept2/ARTS gene, stem cells involved in wound healing live longer and wounds heal faster and more thoroughly than in normal mice. This confocal microscopy image from a mouse lacking the Sept2/ARTS gene shows a tail wound in the process of healing. See more information in the article in Science.

Related to images 3497 and 3500.

Neutrophil-like cells (blue) in a microfluidic chip preferentially migrating toward LTB4 over fMLP. A neutrophil is a type of white blood cell that is part of the immune system and helps the body fight infection. Both LTB4 and fMLP are molecules involved in immune response. Microfluidic chips are small devices containing microscopic channels, and they are used in a range of applications, from basic research on cells to pathogen detection. The scale bar in this video is 500μm.

The membrane that surrounds a cell is made up of proteins and lipids. Depending on the membrane's location and role in the body, lipids can make up anywhere from 20 to 80 percent of the membrane, with the remainder being proteins. Cholesterol (green), which is not found in plant cells, is a type of lipid that helps stiffen the membrane.

The marine bacterium Vibrio harveyi glows when near its kind. This luminescence, which results from biochemical reactions, is part of the chemical communication used by the organisms to assess their own population size and distinguish themselves from other types of bacteria. But V. harveyi only light up when part of a large group. This communication, called quorum sensing, speaks for itself here on a lab dish, where more densely packed areas of the bacteria show up blue. Other types of bacteria use quorum sensing to release toxins, trigger disease, and evade the immune system.

Cross section of human skeletal muscle. Image taken with a confocal fluorescent light microscope.

Researchers use cluster analysis to study protein shape and function. Each green circle represents one potential shape of the protein mitoNEET. The longer the blue line between two circles, the greater the differences between the shapes. Most shapes are similar; they fall into three clusters that are represented by the three images of the protein. From a Rice University news release. Graduate student Elizabeth Baxter and Patricia Jennings, professor of chemistry and biochemistry at UCSD, collaborated with José Onuchic, a physicist at Rice University, on this work.

This is a fibroblast, a connective tissue cell that plays an important role in wound healing. Normal fibroblasts have smooth edges. In contrast, this spiky cell is missing a protein that is necessary for proper construction of the cell's skeleton. Its jagged shape makes it impossible for the cell to move normally. In addition to compromising wound healing, abnormal cell movement can lead to birth defects, faulty immune function, and other health problems.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

These smooth muscle cells were derived from human embryonic stem cells. The nuclei are stained blue, and the proteins of the cytoskeleton are stained green. Image and caption information courtesy of the California Institute for Regenerative Medicine.

Model of a major secreted protein of unknown function, which is only found in mycobacteria, the class of bacteria that causes tuberculosis. Based on structural similarity, this protein may be involved in host-bacterial interactions.

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 2535 for a labeled version of this illustration. Featured in Medicines By Design.

Proteins are long chains of amino acids. Each protein has a unique amino acid sequence. It is still a mystery how a protein folds into the proper shape based on its sequence. Scientists hope that one day they can "watch" this folding process for any given protein. The dream has been realized, at least partially, through the use of computer simulation.