Model of aspartoacylase, a human enzyme involved in brain metabolism.

Composite image of beta-galactosidase showing how cryo-EM’s resolution has improved dramatically in recent years. Older images to the left, more recent to the right. Related to image 5883. NIH Director Francis Collins featured this on his blog on January 14, 2016.

Stained glomeruli in the kidney. The kidney is an essential organ responsible for disposing wastes from the body and for maintaining healthy ion levels in the blood. It works like a purifier by pulling break-down products of metabolism, such as urea and ammonium, from the bloodstream for excretion in urine. The glomerulus is a structure that helps filter the waste compounds from the blood. It consists of a network of capillaries enclosed within a Bowman's capsule of a nephron, which is the structure in which ions exit or re-enter the blood in the kidney.

RNA interference or RNAi is a gene-silencing process in which double-stranded RNAs trigger the destruction of specific RNAs. See 2559 for a labeled version of this illustration. Featured in The New Genetics.

Meiosis is used to make sperm and egg cells. During meiosis, a cell's chromosomes are copied once, but the cell divides twice. During mitosis, the chromosomes are copied once, and the cell divides once. For simplicity, cells are illustrated with only three pairs of chromosomes. See image 6788 for a labeled version of this illustration.

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

A crawling cell with DNA shown in blue and actin filaments, which are a major component of the cytoskeleton, visible in pink. Actin filaments help enable cells to crawl. This image was captured using structured illumination microscopy.

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

A zebrafish head with blood vessels shown in purple. Researchers often study zebrafish because they share many genes with humans, grow and reproduce quickly, and have see-through eggs and embryos, which make it easy to study early stages of development.

This image was captured using a light sheet microscope.

Related to video 6933.

Floral pattern emerging as two bacterial species, motile Acinetobacter baylyi and non-motile Escherichia coli (green), are grown together for 24 hours on 0.75% agar surface from a small inoculum in the center of a Petri dish.

See 6553 for a photo of this process at 48 hours on 1% agar surface.
See 6555 for another photo of this process at 48 hours on 1% agar surface.
See 6556 for a photo of this process at 72 hours on 0.5% agar surface.
See 6550 for a video of this process.

CellPack image of the H1N1 influenza virus, with hemagglutinin and neuraminidase glycoproteins in green and red, respectively, on the outer envelope (white); matrix protein in gray, and ribonucleoprotein particles inside the virus in red and green. Related to image 6356.

Three C. elegans, tiny roundworms, with a ribosomal protein glowing red and muscle fibers glowing green. Researchers used these worms to study a molecular pathway that affects aging. The ribosomal protein is involved in protein translation and may play a role in dietary restriction-induced longevity. Image created using confocal microscopy.
View single roundworm here 6581.
View closeup of roundworms here 6583.

This fluorescent microscope image shows human embryonic stem cells whose nuclei are stained green. Blue staining shows the surrounding supportive feeder cells. Image and caption information courtesy of the California Institute for Regenerative Medicine. See related image 3275.

This image represents the structure of TrpRS, a novel member of the tryptophanyl tRNA-synthetase family of enzymes. By helping to link the amino acid tryptophan to a tRNA molecule, TrpRS primes the amino acid for use in protein synthesis. A cluster of iron and sulfur atoms (orange and red spheres) was unexpectedly found in the anti-codon domain, a key part of the molecule, and appears to be critical for the function of the enzyme. TrpRS was discovered in Thermotoga maritima, a rod-shaped bacterium that flourishes in high temperatures.

These mitochondria (red) are from the heart muscle cell of a rat. Mitochondria have an inner membrane that folds in many places (and that appears here as striations). This folding vastly increases the surface area for energy production. Nearly all our cells have mitochondria. Related to image 3664.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible and lined up.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, and 1019.

This illustration highlights spherical pre-synaptic vesicles that carry the neurotransmitter glutamate. The presynaptic and postsynaptic membranes are shown with proteins relevant for transmitting and modulating the neuronal signal.

PDB 101’s Opioids and Pain Signaling video explains how glutamatergic synapses are involved in the process of pain signaling.

Motor neuron progenitors (green) were derived from human embryonic stem cells. Image and caption information courtesy of the California Institute for Regenerative Medicine.

Model of a protein involved in cell division from Mycoplasma pneumoniae. This model, based on X-ray crystallography, revealed a structural domain not seen before. The protein is thought to be involved in cell division and cell wall biosynthesis.

A light organ (~0.5 mm across) of a juvenile Hawaiian bobtail squid, Euprymna scolopes. Movement of cilia on the surface of the organ aggregates bacterial symbionts (green) into two areas above sets of pores that lead to interior crypts. This image was taken using a confocal fluorescence microscope.

Related to images 7016, 7017, 7019, and 7020.

The nucleus of a degenerating human tendon cell, also known as a tenocyte. It has been color-coded based on the density of chromatin—a substance made up of DNA and proteins. Areas of low chromatin density are shown in blue, and areas of high chromatin density are shown in red. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6887 and 6888.

Two highly stressed osteosarcoma cells are shown with a set of green droplet-like structures followed by a second set of magenta droplets. These droplets are composed of fluorescently labeled stress-response proteins, either G3BP or UBQLN2 (Ubiquilin-2). Each protein is undergoing a fascinating process, called phase separation, in which a non-membrane bound compartment of the cytoplasm emerges with a distinct environment from the surrounding cytoplasm. Subsequently, the proteins fuse with like proteins to form larger droplets, in much the same way that raindrops merge on a car’s windshield.

Related to image 5871.

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-in version 5767 of this illustration.

Fruit fly sperm cells glow bright green when they express the gene for green fluorescent protein (GFP).

Multicellular yeast called snowflake yeast that researchers created through many generations of directed evolution from unicellular yeast. Cells are connected to one another by their cell walls, shown in blue. Stained cytoplasm (green) and membranes (magenta) show that the individual cells remain separate. This image was captured using spinning disk confocal microscopy.

Related to images 6969 and 6971.

This image shows the structure of the CYP17A1 enzyme (ribbons colored from blue N-terminus to red C-terminus), with the associated heme colored black. The prostate cancer drug abiraterone is colored gray. Cytochrome P450 enzymes bind to and metabolize a variety of chemicals, including drugs. Cytochrome P450 17A1 also helps create steroid hormones. Emily Scott's lab is studying how CYP17A1 could be selectively inhibited to treat prostate cancer. She and graduate student Natasha DeVore elucidated the structure shown using X-ray crystallography. Dr. Scott created the image (both white bg and transparent bg) for the NIGMS image gallery. See the "Medium-Resolution Image" for a PNG version of the image that is transparent.

Muscles stretch and contract when we walk, and skin splits open and knits back together when we get a paper cut. To study these contractile forces, researchers built a three-dimensional scaffold that mimics tissue in an organism. Researchers poured a mixture of cells and elastic collagen over microscopic posts in a dish. Then they studied how the cells pulled and released the posts as they formed a web of tissue. To measure forces between posts, the researchers developed a computer model. Their findings--which show that contractile forces vary throughout the tissue--could have a wide range of medical applications.

These yeast cells were exposed to a glucose (sugar) shortage. This caused the cells to compartmentalize HMGCR (green)—an enzyme involved in making cholesterol—to a patch on the nuclear envelope next to the vacuole/lysosome (purple). This process enhanced HMGCR activity and helped the yeast adapt to the glucose shortage. Researchers hope that understanding how yeast regulate cholesterol could ultimately lead to new ways to treat high cholesterol in people. This image was captured using a fluorescence microscope.

To become products, reactants must overcome an energy hill. See image 2525 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

These developing mouse nerve cells have a nucleus (yellow) surrounded by a cell body, with long extensions called axons and thin branching structures called dendrites. Electrical signals travel from the axon of one cell to the dendrites of another.

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

A study published in March 2012 used cryo-electron microscopy to determine the structure of the DNA replication origin recognition complex (ORC), a semi-circular, protein complex (yellow) that recognizes and binds DNA to start the replication process. The ORC appears to wrap around and bend approximately 70 base pairs of double stranded DNA (red and blue). Also shown is the protein Cdc6 (green), which is also involved in the initiation of DNA replication. Related to video 3307 that shows the structure from different angles. From a Brookhaven National Laboratory news release, "Study Reveals How Protein Machinery Binds and Wraps DNA to Start Replication."

Crystals of fungal lipase protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

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.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to images 3413, 3414, 3415, 3416, 3418, and 3419.

This tropical scene, reminiscent of a postcard from Key West, is actually a petri dish containing an artistic arrangement of genetically engineered bacteria. The image showcases eight of the fluorescent proteins created in the laboratory of the late Roger Y. Tsien, a cell biologist at the University of California, San Diego. Tsien, along with Osamu Shimomura of the Marine Biology Laboratory and Martin Chalfie of Columbia University, share the 2008 Nobel Prize in chemistry for their work on green fluorescent protein-a naturally glowing molecule from jellyfish that has become a powerful tool for studying molecules inside living cells.

A knotted protein from an archaebacterium called Methanobacterium thermoautotrophicam. This organism breaks down waste products and produces methane gas. Protein folding theory previously held that forming a knot was beyond the ability of a protein, but this structure, determined at Argonne's Structural Biology Center, proves differently. Researchers theorize that this knot stabilizes the amino acid subunits of the protein.

This image shows the hierarchical ontology of genes, cellular components and processes derived from large genomic datasets. From Dutkowski et al. A gene ontology inferred from molecular networks Nat Biotechnol. 2013 Jan;31(1):38-45. Related to 3437.

Coronaviruses are enveloped viruses responsible for 30 percent of mild respiratory infections and atypical deadly pneumonia in humans worldwide. These deadly pneumonia include those caused by infections with severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). The coronavirus spike glycoprotein mediates virus entry into cells and represents an important therapeutic target. The illustration shows a viral membrane decorated with spike glycoproteins; highlighted in red is a potential neutralization site, which is a protein sequence that might be used as a target for vaccines to combat viruses such as MERS-CoV and other coronaviruses.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to images 3413, 3414, 3415, 3416, 3417, and 3418.

This lab space was designed for work on the induced pluripotent stem (iPS) cell collection, part of the NIGMS Human Genetic Cell Repository at the Coriell Institute for Medical Research.

Blood vessels at the back of the eye (retina) are used to diagnose glaucoma and diabetic eye disease. They also display characteristic changes in people with high blood pressure. In the image, the vessels appear green. It's not actually the vessels that are stained green, but rather filaments of a protein called actin that wraps around the vessels. Most of the red blood cells were replaced by fluid as the tissue was prepared for the microscope. The tiny red dots are red blood cells that remain in the vessels. The image was captured using confocal and 2-photon excitation microscopy for a project related to neurofibromatosis.

Lysosomes have powerful enzymes and acids to digest and recycle cell materials.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible and are starting to line up.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1017, 1018, 1019, and 1021.

This fruit fly expresses green fluorescent protein (GFP) in the same pattern as the period gene, a gene that regulates circadian rhythm and is expressed in all sensory neurons on the surface of the fly.

This image shows a computer-generated, three-dimensional map of the rotavirus structure. This virus infects humans and other animals and causes severe diarrhea in infants and young children. By the age of five, almost every child in the world has been infected with this virus at least once. Scientists have found a vaccine against rotavirus, so in the United States there are very few fatalities, but in developing countries and in places where the vaccine is unavailable, this virus is responsible for more than 200,000 deaths each year.

The rotavirus comprises three layers: the outer, middle and inner layers. On infection, the outer layer is removed, leaving behind a "double-layered particle." Researchers have studied the structure of this double-layered particle with a transmission electron microscope. Many images of the virus at a magnification of ~50,000x were acquired, and computational analysis was used to combine the individual particle images into a three-dimensional reconstruction.

The image was rendered by Melody Campbell (PhD student at TSRI). Work that led to the 3D map was published in Campbell et al. Movies of ice-embedded particles enhance resolution in electron cryo-microscopy. Structure. 2012;20(11):1823-8. PMCID: PMC3510009.

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

This image shows neonatal mouse heart cells. These cells were grown in the lab on a chip that aligns the cells in a way that mimics what is normally seen in the body. Green shows the protein N-cadherin, which indicates normal connections between cells. Red indicates the muscle protein actin, and blue indicates the cell nuclei. The work shown here was part of a study attempting to grow heart tissue in the lab to repair damage after a heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to images 3281 and 3283.

A peripheral nerve cell made from human embryonic stem cell-derived neural crest stem cells. The nucleus is shown in blue, and nerve cell proteins peripherin and beta-tubulin (Tuj1) are shown in green and red, respectively. Related to image 3263.

Cell mopping up.

Ovarioles in female insects are tubes in which egg cells (called oocytes) form at one end and complete their development as they reach the other end of the tube. This image, taken with a confocal microscope, shows ovarioles in a very popular lab animal, the fruit fly Drosophila. The basic structure of ovarioles supports very rapid egg production, with some insects (like termites) producing several thousand eggs per day. Each insect ovary typically contains four to eight ovarioles, but this number varies widely depending on the insect species.

Scientists use insect ovarioles, for example, to study the basic processes that help various insects, including those that cause disease (like some mosquitos and biting flies), reproduce very quickly.