Drugs enter different layers of skin via intramuscular, subcutaneous, or transdermal delivery methods. See image 2531 for an unlabeled version of this illustration. Featured in Medicines By Design.

Like a map showing heavily traveled roads, this mathematical model of metabolic activity inside an E. coli cell shows the busiest pathway in white. Reaction pathways used less frequently by the cell are marked in red (moderate activity) and green (even less activity). Visualizations like this one may help scientists identify drug targets that block key metabolic pathways in bacteria.

This sculpture made of purple and clear glass beads depicts bacteriophage Phi174, a virus that infects bacteria. It rests on a surface that portrays an adaptive landscape, a conceptual visualization. The ridges represent the gene combinations associated with the greatest fitness levels of the virus, as measured by how quickly the virus can reproduce itself. Phi174 is an important model system for studies of viral evolution because its genome can readily be sequenced as it evolves under defined laboratory conditions.

Undifferentiated embryonic stem cells cease to exist a few days after conception. In this image, ES cells are shown to differentiate into sperm, muscle fiber, hair cells, nerve cells, and cone cells.

Individual cells are color-coded based on their identity and signaling activity using a protein circuit technology developed by the Coyle Lab. Just as a radio allows you to listen to an individual frequency, this technology allows researchers to tune into the specific “radio station” of each cell through genetically encoded proteins from a bacterial system called MinDE. The proteins generate an oscillating fluorescent signal that transmits information about cell shape, state, and identity that can be decoded using digital signal processing tools originally designed for telecommunications. The approach allows researchers to look at the dynamics of a single cell in the presence of many other cells.

Related to video 7022.

Cell-like compartments that spontaneously emerged from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. Image created using confocal microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6586, 6591, 6592.

For videos of cell-like compartments from frog eggs view: 6587, 6588, 6589, and 6590.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to images 3413, 3414, 3415, 3416, 3417, and 3419.

Some children are born with a mutation in a regulatory site on this enzyme that causes them to over-secrete insulin when they consume protein. We found that a compound from green tea (shown in the stick figure and by the yellow spheres on the enzyme) is able to block this hyperactivity when given to animals with this disorder.

An RNA molecule dynamically refolds itself as it is being synthesized. When the RNA is short, it ties itself into a “knot” (dark purple). For this domain to slip its knot, about 5 seconds into the video, another newly forming region (fuchsia) wiggles down to gain a “toehold.” About 9 seconds in, the temporarily knotted domain untangles and unwinds. Finally, at about 23 seconds, the strand starts to be reconfigured into the shape it needs to do its job in the cell.

The cells shown here are fibroblasts, one of the most common cells in mammalian connective tissue. These particular cells were taken from a mouse embryo. Scientists used them to test the power of a new microscopy technique that offers vivid views of the inside of a cell. The DNA within the nucleus (blue), mitochondria (green), and actin filaments in the cellular skeleton (red) are clearly visible.

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

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Using X-ray crystallography, researchers determined the structure of a CCD-1 molecule and a molecule of the antibiotic cefotaxime bound together. The structure revealed that CCD-1 provides extensive hydrogen bonding and stabilization of the antibiotic in the active site, leading to efficient degradation of the antibiotic.

Related to images 6764, 6765, and 6767.

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 1051.

The image visualizes a part of the yeast molecular interaction network. The lines in the network represent connections among genes (shown as little dots) and different-colored networks indicate subnetworks, for instance, those in specific locations or pathways in the cell. Researchers use gene or protein expression data to build these networks; the network shown here was visualized with a program called Cytoscape. By following changes in the architectures of these networks in response to altered environmental conditions, scientists can home in on those genes that become central "hubs" (highly connected genes), for example, when a cell encounters stress. They can then further investigate the precise role of these genes to uncover how a cell's molecular machinery deals with stress or other factors. Related to images 3732 and 3733.

This Petri dish contains microscopic roundworms called Caenorhabditis elegans. Researchers used these particular worms to study how C. elegans senses the color of light in its environment.

If a picture is worth a thousand words, what's a movie worth? For researchers studying cell migration, a "documentary" of fruit fly cells (bright green) traversing an egg chamber could answer longstanding questions about cell movement. Historically, researchers have been unable to watch this cell migration unfold in living ovarian tissue in real time. But by developing a culture medium that allows fly eggs to survive outside their ovarian homes, scientists can observe the nuances of cell migration as it happens. Such details may shed light on how immune cells move to a wound and why cancer cells spread to other sites. See 3594 for still image.

After multiplying inside a host cell, the stringlike Ebola virus is emerging to infect more cells. Ebola is a rare, often fatal disease that occurs primarily in tropical regions of sub-Saharan Africa. The virus is believed to spread to humans through contact with wild animals, especially fruit bats. It can be transmitted between one person and another through bodily fluids.

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

This photo shows a Varian Unity Inova 900 MHz, 21.1 T standard bore magnet Nuclear Magnetic Resonnance (NMR) spectrometer. NMR spectroscopy provides data used to determine the structures of proteins in solution, rather than in crystal form, as in X-ray crystallography. The technique is limited to smaller proteins or protein fragments in a high throughput approach.

Skins cells were reprogrammed into heart muscle cells. The cells highlighted in green are remaining skin cells. Red indicates a protein that is unique to heart muscle. The technique used to reprogram the skin cells into heart cells could one day be used to mend heart muscle damaged by disease or heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine.

These cells get their name from the hairlike structures that extend from them into the fluid-filled tube of the inner ear. When sound reaches the ear, the hairs bend and the cells convert this movement into signals that are relayed to the brain. When we pump up the music in our cars or join tens of thousands of cheering fans at a football stadium, the noise can make the hairs bend so far that they actually break, resulting in long-term hearing loss.

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

An image of Caenorhabditis elegans, a tiny roundworm, showing internal structures including the intestine, pharynx, and body wall muscle. C. elegans is one of the simplest organisms with a nervous system. Scientists use it to study nervous system development, among other things. This image was captured with a quantitative orientation-independent differential interference contrast (OI-DIC) microscope. The scale bar is 100 µm.

More information about the microscopy that produced this image can be found in the Journal of Microscopy paper by Malamy and Shribak.

Two fruit fly (Drosophila melanogaster) larvae brains with neurons expressing fluorescently tagged tubulin protein. Tubulin makes up strong, hollow fibers called microtubules that play important roles in neuron growth and migration during brain development. This image was captured using confocal microscopy, and the color indicates the position of the neurons within the brain.

Yeast cells with the protein Fimbrin Fim1 shown in magenta. This protein plays a role in cell division. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6797, 6798, and videos 6795 and 6796.

Multiple anthrax bacteria (green) being enveloped by an immune system cell (purple). Anthrax bacteria live in soil and form dormant spores that can survive for decades. When animals eat or inhale these spores, the bacteria activate and rapidly increase in number. Today, a highly effective and widely used vaccine has made the disease uncommon in domesticated animals and rare in humans.

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

The human body keeps time with a master clock called the suprachiasmatic nucleus or SCN. Situated inside the brain, it's a tiny sliver of tissue about the size of a grain of rice, located behind the eyes. It sits quite close to the optic nerve, which controls vision, and this means that the SCN "clock" can keep track of day and night. The SCN helps control sleep by coordinating the actions of billions of miniature "clocks" throughout the body. These aren't actually clocks, but rather are ensembles of genes inside clusters of cells that switch on and off in a regular, 24-hour cycle in our physiological day.

Real-time footage of Caenorhabditis elegans, a tiny roundworm, trapped by a carnivorous fungus, Arthrobotrys dactyloides. This fungus makes ring traps in response to the presence of C. elegans. When a worm enters a ring, the trap rapidly constricts so that the worm cannot move away, and the fungus then consumes the worm. The size of the imaged area is 0.7mm x 0.9mm.

This video was obtained with a polychromatic polarizing microscope (PPM) in white light that shows the polychromatic birefringent image with hue corresponding to the slow axis orientation. More information about PPM can be found in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak.

Yeast cells that abnormally accumulate cell wall material (blue) at their ends and, when preparing to divide, in their middles. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6794, 6798, and videos 6795 and 6796.

Learn how research organisms, such as fruit flies and mice, can help us understand and treat human diseases. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

Bacillus anthracis (anthrax) cells being killed by a fluorescent trans-translation inhibitor, which disrupts bacterial protein synthesis. The inhibitor is naturally fluorescent and looks blue when it is excited by ultraviolet light in the microscope. This is a color version of Image 3481.

The two large, central, round shapes are ovaries from a typical fruit fly (Drosophila melanogaster). The small butterfly-like structures surrounding them are fruit fly ovaries where researchers suppressed the expression of a gene that controls microtubule polymerization and is necessary for normal development. This image was captured using a confocal laser scanning microscope.

Related to image 6807.

The long, stringy DNA that makes up genes is spooled within chromosomes inside the nucleus of a cell. (Note that a gene would actually be a much longer stretch of DNA than what is shown here.) See image 2540 for a labeled version of this illustration. Featured in The New Genetics.

This animation shows atoms of the HIV capsid, the shell that encloses the virus's genetic material. Scientists determined the exact structure of the capsid using a variety of imaging techniques and analyses. They then entered this data into a supercomputer to produce this image. Related to image 3477.

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 6887 and 6893.

Gram-negative bacteria perform molecular acrobatics just to eat. Because they're encased by two membranes, they must haul nutrients across both. To test one theory of how the bacteria manage this feat, researchers used computer simulations of two proteins involved in importing vitamin B12. Here, the protein (red) anchored in the inner membrane of bacteria tugs on a much larger protein (green and blue) in the outer membrane. Part of the larger protein unwinds, creating a pore through which the vitamin can pass.

Cryo-electron microscopy (cryo-EM) has the power to capture details of proteins and other small biological structures at the molecular level.  This image shows proteins in the capsid, or outer cover, of bacteriophage P22, a virus that infects the Salmonella bacteria. Each color shows the structure and position of an individual protein in the capsid. Thousands of cryo-EM scans capture the structure and shape of all the individual proteins in the capsid and their position relative to other proteins. A computer model combines these scans into the three-dimension image shown here. Related to image 5875.

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.

A cross section of the measles virus in which six proteins work together to infect cells. The measles virus is extremely infectious; 9 out of 10 people exposed will contract the disease. Fortunately, an effective vaccine protects against infection.

For a zoomed-in look at the six important proteins, see Measles Virus Proteins.

An adult Hawaiian bobtail squid, Euprymna scolopes, swimming next to a submerged hand.

Related to image 7010 and video 7012.

Arranging exons in different patterns, called alternative splicing, enables cells to make different proteins from a single gene. See image 2553 for a labeled version of this illustration. Featured in The New Genetics.

Electron density maps such as this one are generated from the diffraction patterns of X-rays passing through protein crystals. These maps are then used to generate a model of the protein's structure by fitting the protein's amino acid sequence (yellow) into the observed electron density (blue).

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.

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.

This ACAPELLA robot for capillary protein crystallization grows protein crystals, freezes them, and centers them without manual intervention. The close-up is a view of one of the dispensers used for dispensing proteins and reagents.

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 captures the many layers of nerve cells in the retina. The top layer (green) is made up of cells called photoreceptors that convert light into electrical signals to relay to the brain. The two best-known types of photoreceptor cells are rod- and cone-shaped. Rods help us see under low-light conditions but can't help us distinguish colors. Cones don't function well in the dark but allow us to see vibrant colors in daylight.

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

A cell in interphase, at the start of mitosis: Chromosomes duplicate, and the copies remain attached to each other. Mitosis is responsible for growth and development, as well as for replacing injured or worn out cells throughout the body. For simplicity, mitosis is illustrated here with only six chromosomes.

NIGMS-funded researchers led by Roger Kornberg solved the structure of RNA polymerase II. This is the enzyme in mammalian cells that catalyzes the transcription of DNA into messenger RNA, the molecule that in turn dictates the order of amino acids in proteins. For his work on the mechanisms of mammalian transcription, Kornberg received the Nobel Prize in Chemistry in 2006.

Spinal nerves are part of the peripheral nervous system. They run within the spinal column to carry nerve signals to and from all parts of the body. The spinal nerves enable all the movements we do, from turning our heads to wiggling our toes, control the movements of our internal organs, such as the colon and the bladder, as well as allow us to feel touch and the location of our limbs.

Learn how curiosity about the world and our cells is key to scientific discoveries. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

Relapsing fever is caused by a bacterium and transmitted by certain soft-bodied ticks or body lice. The disease is seldom fatal in humans, but it can be very serious and prolonged. This scanning electron micrograph shows Borrelia hermsii (green), one of the bacterial species that causes the disease, interacting with red blood cells. Micrograph by Robert Fischer, NIAID.

For more information on this see, relapsing fever.

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

Cdc42, a member of the Rho family of small guanosine triphosphatase (GTPase) proteins, regulates multiple cell functions, including motility, proliferation, apoptosis, and cell morphology. In order to fulfill these diverse roles, the timing and location of Cdc42 activation must be tightly controlled. Klaus Hahn and his research group use special dyes designed to report protein conformational changes and interactions, here in living neutrophil cells. Warmer colors in this image indicate higher levels of activation. Cdc42 looks to be activated at cell protrusions.

Related to images 2451, 2452, and 2453.