Mitochondria are the powerhouses of the cells, generating the energy the cells need to do their tasks and to stay alive. Researchers have studied mitochondria for some time because when these cell organelles don't work as well as they should, several diseases develop. In this photograph of cow cells taken with a microscope, the mitochondria were stained in bright yellow to visualize them in the cell. The large blue dots are the cell nuclei and the gray web is the cytoskeleton of the cells.

Many of today's medicines come from products found in nature, such as this sponge found off the coast of Palau in the Pacific Ocean. Chemists have synthesized a compound called Palau'amine, which appears to act against cancer, bacteria and fungi. In doing so, they invented a new chemical technique that will empower the synthesis of other challenging molecules.

This image captures the spiral-shaped ovary of an anglerfish in cross-section. Once matured, these eggs will be released in a gelatinous, floating mass. For some species of anglerfish, this egg mass can be up to 3 feet long and include nearly 200,000 eggs.

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

This time-lapse movie shows that bacterial communities called biofilms can create blockages that prevent fluid flow in devices such as stents and catheters over a period of about 56 hours. This video was featured in a news release from Princeton University.

Here, bubonic plague bacteria (yellow) are shown in the digestive system of a rat flea (purple). The bubonic plague killed a third of Europeans in the mid-14th century. Today, it is still active in Africa, Asia, and the Americas, with as many as 2,000 people infected worldwide each year. If caught early, bubonic plague can be treated with antibiotics.

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

This normal human skin cell was treated with a growth factor that triggered the formation of specialized protein structures that enable the cell to move. We depend on cell movement for such basic functions as wound healing and launching an immune response.

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

Model of the enzyme aminopeptidase N from the human pathogen Neisseria meningitidis, which can cause meningitis epidemics. The structure provides insight on the active site of this important molecule.

The arrangement of identical molecular components can make a dramatic difference. For example, carbon atoms can be arranged into dull graphite (left) or sparkly diamonds (right). See image 2506 for an illustration without examples.

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.

Melanoma (skin cancer) cells undergoing programmed cell death, also called apoptosis. This process was triggered by raising the pH of the medium that the cells were growing in. Melanoma in people cannot be treated by raising pH because that would also kill healthy cells. This video was taken using a differential interference contrast (DIC) microscope.

Cells move forward with lamellipodia and filopodia supported by networks and bundles of actin filaments. Proper, controlled cell movement is a complex process. Recent research has shown that an actin-polymerizing factor called the Arp2/3 complex is the key component of the actin polymerization engine that drives amoeboid cell motility. ARPC3, a component of the Arp2/3 complex, plays a critical role in actin nucleation. In this photo, the ARPC3+/+ fibroblast cells were fixed and stained with Alexa 546 phalloidin for F-actin (red) and DAPI to visualize the nucleus (blue). ARPC3+/+ fibroblast cells with lamellipodia leading edge. Related to images 3328, 3329, 3330, 3331, and 3333.

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.

Various views of a mouse brain that was genetically modified so that subpopulations of its neurons glow. Researchers often study mice because they share many genes with people and can shed light on biological processes, development, and diseases in humans.

This video was captured using a light sheet microscope.

Related to images 6929 and 6930.

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

Enzymes convert substrates into products very quickly. See image 2521 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

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.

Cells move forward with lamellipodia and filopodia supported by networks and bundles of actin filaments. Proper, controlled cell movement is a complex process. Recent research has shown that an actin-polymerizing factor called the Arp2/3 complex is the key component of the actin polymerization engine that drives amoeboid cell motility. ARPC3, a component of the Arp2/3 complex, plays a critical role in actin nucleation. In this photo, the ARPC3+/+ fibroblast cells were fixed and stained with Alexa 546 phalloidin for F-actin (red), mDia1 (green), and DAPI to visualize the nucleus (blue). mDia1 is localized at the lamellipodia of ARPC3+/+ fibroblast cells. Related to images 3328, 3329, 3331, 3332, and 3333.

Originally from the waters of India, Nepal, and neighboring countries, zebrafish can now be found swimming in science labs (and home aquariums) throughout the world. This fish is a favorite study subject for scientists interested in how genes guide the early stages of prenatal development (including the developing fin shown here) and in the effects of environmental contamination on embryos.

In this image, green fluorescent protein (GFP) is expressed where the gene sox9b is expressed. Collagen (red) marks the fin rays, and DNA, stained with a dye called DAPI, is in blue. sox9b plays many important roles during development, including the building of the heart and brain, and is also necessary for skeletal development. At the University of Wisconsin, researchers have found that exposure to contaminants that bind the aryl-hydrocarbon receptor results in the downregulation of sox9b. Loss of sox9b severely disrupts development in zebrafish and causes a life-threatening disorder called campomelic dysplasia (CD) in humans. CD is characterized by cardiovascular, neural, and skeletal defects. By studying the roles of genes such as sox9b in zebrafish, scientists hope to better understand normal development in humans as well as how to treat developmental disorders and diseases.

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

Antibodies are among the most promising therapies for certain forms of cancer, but patients must take them intravenously, exposing healthy tissues to the drug and increasing the risk of side effects. A team of biochemists packed the anticancer antibodies into porous silica particles to deliver a heavy dose directly to tumors in mice.

Xenopus laevis, the African clawed frog, has long been used as a model organism for studying embryonic development. The frog embryo on the left lacks the developmental factor Sizzled. A normal embryo is shown on the right.

A microtubule, part of the cell's skeleton, builds and deconstructs.

T cells engulf and digest cells displaying markers (or antigens) for retroviruses, such as HIV.

NIGMS staff are located in the Natcher Building on the NIH campus.

The goal of the Protein Structure Initiative (PSI) is to determine the three-dimensional shapes of a wide range of proteins by solving the structures of representative members of each protein family found in nature. The collection of structures should serve as a valuable resource for biomedical research scientists.

Influenza A infects a host cell when hemagglutinin grips onto glycans on its surface. Neuraminidase, an enzyme that chews sugars, helps newly made virus particles detach so they can infect other cells. Related to 213. Featured in the March 2006, issue of Findings in "Viral Voyages."

The molecule on the left is an electrostatic potential map of the van der Waals surface of the transition state for human purine nucleoside phosphorylase. The colors indicate the electron density at any position of the molecule. Red indicates electron-rich regions with negative charge and blue indicates electron-poor regions with positive charge. The molecule on the right is called DADMe-ImmH. It is a chemically stable analogue of the transition state on the left. It binds to the enzyme millions of times tighter than the substrate. This inhibitor is in human clinical trials for treating patients with gout. This image appears in Figure 4, Schramm, V.L. (2011) Annu. Rev. Biochem. 80:703-732.

Two adult fruit flies (Drosophila)

On the left, a cross-section slice of a rat pancreas cell captured using cryo-electron tomography (cryo-ET). On the right, a color-coded, 3D version of the image highlighting cell structures. Visible features include insulin vesicles (purple rings), insulin crystals (gray circles), microtubules (green rods), ribosomes (small yellow circles). The black line at the bottom right of the left image represents 200 nm. Related to image 6608.

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 black-and-white version of Image 3525.

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.

Multiphoton fluorescence image of cultured HeLa cells with a fluorescent protein targeted to the Golgi apparatus (orange), microtubules (green) and counterstained for DNA (cyan). Nikon RTS2000MP custom laser scanning microscope. See related images 3518, 3519, 3520, 3521.

The enzyme Dicer generates microRNAs by chopping larger RNA molecules into tiny Velcro^®-like pieces. MicroRNAs stick to mRNA molecules and prevent the mRNAs from being made into proteins. See image 2556 for an unlabeled version of this illustration. Featured in The New Genetics.

The green spots in this mouse brain are cells labeled with Calling Cards, a technology that records molecular events in brain cells as they mature. Understanding these processes during healthy development can guide further research into what goes wrong in cases of neuropsychiatric disorders. Also fluorescently labeled in this image are neurons (red) and nuclei (blue). Calling Cards and its application are described in the Cell paper “Self-Reporting Transposons Enable Simultaneous Readout of Gene Expression and Transcription Factor Binding in Single Cells” by Moudgil et al.; and the Proceedings of the National Academy of Sciences paper “A viral toolkit for recording transcription factor–DNA interactions in live mouse tissues” by Cammack et al. The technology was also featured in the NIH Director’s Blog post The Amazing Brain: Tracking Molecular Events with Calling Cards.

Related to video

About half of all human proteins include chains of sugar molecules that are critical for the proteins to function properly. Appears in the NIGMS booklet Inside the Cell.

This image shows a layer of retinal pigment epithelium cells derived from human embryonic stem cells, highlighting the nuclei (red) and cell surfaces (green). This kind of retinal cell is responsible for macular degeneration, the most common cause of blindness. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to image 3286

Model based on X-ray crystallography of the structure of a small heat shock protein complex from the bacteria, Methanococcus jannaschii. Methanococcus jannaschii is an organism that lives at near boiling temperature, and this protein complex helps it cope with the stress of high temperature. Similar complexes are produced in human cells when they are "stressed" by events such as burns, heart attacks, or strokes. The complexes help cells recover from the stressful event.

Details about the basic biology and chemistry of the ingredients that produce bioluminescence are allowing scientists to harness it as an imaging tool. Credit: Nathan Shaner, Scintillon Institute.

From Biomedical Beat article July 2017: Chasing Fireflies—and Better Cellular Imaging Techniques

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. The image shows a side view of the structure of a protein composed of two smaller proteins, called E and M. Each E and M contributes two molecules to the overall protein structure (called a heterotetramer), which is important for assembling and holding together the viral membrane, i.e., the shell that surrounds the genetic material of the dengue virus. The dengue protein's structure has revealed some portions in the protein that might be good targets for developing medications that could be used to combat dengue virus infections. 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.

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

Like a pulsing blue shower, E. coli cells flash in synchrony. Genes inserted into each cell turn a fluorescent protein on and off at regular intervals. When enough cells grow in the colony, a phenomenon called quorum sensing allows them to switch from blinking independently to blinking in unison. Researchers can watch waves of light propagate across the colony. Adjusting the temperature, chemical composition or other conditions can change the frequency and amplitude of the waves. Because the blinks react to subtle changes in the environment, synchronized oscillators like this one could one day allow biologists to build cellular sensors that detect pollutants or help deliver drugs.

This video simulation shows what an uncontrolled outbreak of transmissible avian flu among people living in Thailand might look like. Red indicates new cases while green indicates areas where the epidemic has finished. The video shows the spread of infection and recovery over 300 days in Thailand and neighboring countries.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. The CRISPR system has two components joined together: a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence) and a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA). In this frame (2 of 4), the CRISPR machine locates the target DNA sequence once inserted into a cell.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video, and find the full CRIPSR illustration here.

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.

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. This is the lateral and overhead (Bottom) view.
For imagery of the overhead view go to 3557.
For imagery of the lateral view go to 3558.
For more information about the illumated area go to 3559.

3D image of Caulobacter bacterium with various components highlighted: cell membranes (red and blue), protein shell (green), protein factories known as ribosomes (yellow), and storage granules (orange).

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.

Ribonucleic acid (RNA) has a sugar-phosphate backbone and the bases adenine (A), cytosine (C), guanine (G), and uracil (U). See image 2555 for a labeled version of this illustration. Featured in The New Genetics.

Researchers doing behavioral experiments with honeybees sometimes use paint or enamel to give individual bees distinguishing marks. The elaborate social structure and impressive learning and navigation abilities of bees make them good models for behavioral and neurobiological research. Since the sequencing of the honeybee genome, published in 2006, bees have been used increasingly for research into the molecular basis for social interaction and other complex behaviors.

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, 2453, and 2454.

Bacteria engineered to act as genetic clocks flash in synchrony. Here, a "supernova" burst in a colony of coupled genetic clocks just after reaching critical cell density. Superimposed: A diagram from the notebook of Christiaan Huygens, who first characterized synchronized oscillators in the 17th century.