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.

A 3D reconstruction of a transient receptor potential channel called TRPV5 that was created based on cryo-electron microscopy images. TRPV5 is primarily found in kidney cells and is essential for reabsorbing calcium into the blood.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. This video shows flashing cells as they multiply over the course of more than 12 hours. In response to a stressful environment like one lacking food, B. subtilis activates a large set of genes that help it respond to the hardship. Instead of leaving those genes on as previously thought, researchers discovered that the bacteria flip the genes on and off, increasing the frequency of these pulses with increasing stress. See entry 3253 for a related still image.

Zinc is required for the function of more than 300 enzymes, including those that help regulate gene expression, in various organisms including humans. Researchers study how plants acquire, sequester and distribute zinc to find ways to increase the zinc content of crops to improve human health. Using synchrotron X-ray fluorescence technology, they created this heat map of zinc levels in an Arabidopsis thaliana plant leaf. This image is a winner of the 2015 FASEB Bioart contest and was featured in the NIH Director's blog.

You are face to face with a 6-day-old zebrafish larva. What look like eyes will become nostrils, and the bulges on either side will become eyes. Scientists use fast-growing, transparent zebrafish to see body shapes form and organs develop over the course of just a few days. Images like this one help researchers understand how gene mutations can lead to facial abnormalities such as cleft lip and palate in people.

This image won a 2016 FASEB BioArt award. In addition, NIH Director Francis Collins featured this on his blog on January 26, 2017.

Hydra magnipapillata is an invertebrate animal used as a model organism to study developmental questions, for example the formation of the body axis.

Model of a protein, antigen 85B, that is the most abundant protein exported by Mycobacterium tuberculosis, which causes most cases of tuberculosis. Antigen 85B is involved in building the bacterial cell wall and is an attractive drug target. Based on its structure, scientists have suggested a new class of antituberculous drugs.

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 3498.

DNA encodes RNA, which encodes protein. DNA is transcribed to make messenger RNA (mRNA). The mRNA sequence (dark red strand) is complementary to the DNA sequence (blue strand). On ribosomes, transfer RNA (tRNA) reads three nucleotides at a time in mRNA to bring together the amino acids that link up to make a protein. See image 2548 for a labeled version of this illustration and 2549 for a labeled and numbered version. Featured in The New Genetics.

Animation for the vesicular shuttle model of Golgi transport.

These images model the molecular structures of three enzymes with critical roles in the life cycle of the human immunodeficiency virus (HIV). At the top, reverse transcriptase (orange) creates a DNA copy (yellow) of the virus's RNA genome (blue). In the middle image, integrase (magenta) inserts this DNA copy in the DNA genome (green) of the infected cell. At the bottom, much later in the viral life cycle, protease (turquoise) chops up a chain of HIV structural protein (purple) to generate the building blocks for making new viruses. See these enzymes in action on PDB 101’s video A Molecular View of HIV Therapy.

The cone cell of the eye allows you to see in color. Appears in the NIGMS booklet Inside the Cell.

Like a watch wrapped around a wrist, a special enzyme encircles the double helix to repair a broken strand of DNA. Without molecules that can mend such breaks, cells can malfunction, die, or become cancerous. Related to image 2330.

Viruses have been the foes of animals and other organisms for time immemorial. For almost as long, they've stayed well hidden from view because they are so tiny (they aren't even cells, so scientists call the individual virus a "particle"). This image shows a molecular model of a particle of the Rous sarcoma virus (RSV), a virus that infects and sometimes causes cancer in chickens. In the background is a photo of red blood cells. The particle shown is "immature" (not yet capable of infecting new cells) because it has just budded from an infected chicken cell and entered the bird's bloodstream. The outer shell of the immature virus is made up of a regular assembly of large proteins (shown in red) that are linked together with short protein molecules called peptides (green).  This outer shell covers and protects the proteins (blue) that form the inner shell of the particle. But as you can see, the protective armor of the immature virus contains gaping holes. As the particle matures, the short peptides are removed and the large proteins rearrange, fusing together into a solid sphere capable of infecting new cells. While still immature, the particle is vulnerable to drugs that block its development. Knowing the structure of the immature particle may help scientists develop better medications against RSV and similar viruses in humans. Scientists used sophisticated computational tools to reconstruct the RSV atomic structure by crunching various data on the RSV proteins to simulate the entire structure of immature RSV.

These neurons are derived from mouse embryonic stem cells. Red shows cells making a protein called TH that is characteristic of the neurons that degenerate in Parkinson's disease. Green indicates a protein that's found in all neurons. Blue indicates the nuclei of all cells. Studying dopaminergic neurons can help researchers understand the origins of Parkinson's disease and could be used to screen potential new drugs. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to images 3270 and 3285.

The enzyme CCP is found in the mitochondria of baker’s yeast. Scientists study the chemical reactions that CCP triggers, which involve a water molecule, iron, and oxygen. This structure was determined using an X-ray free electron laser.

Staphylococcus aureus bacteria (blue) on the porous coating of a femoral hip stem used in hip replacement surgery. The relatively rough surface of an implant is a favorable environment for bacteria to attach and grow. This can lead to the development of biofilms, which can cause infections. The researchers who took this image are working to understand where biofilms are likely to develop. This knowledge could support the prevention and treatment of infections. A scanning electron microscope was used to capture this image.

More information on the research that produced this image can be found in the Antibiotics paper "Free-floating aggregate and single-cell-initiated biofilms of Staphylococcus aureus" by Gupta et al.

Related to image 6803 and video 6805.

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 3436.

Vibrio, a type (genus) of rod-shaped bacteria. Some Vibrio species cause cholera in humans.

Nucleotides in DNA are copied into RNA, where they are read three at a time to encode the amino acids in a protein. Many parts of a protein fold as the amino acids are strung together.

See image 2510 for a labeled version of this illustration.

Featured in The Structures of Life.

Like a strand of white pearls, DNA wraps around an assembly of special proteins called histones (colored) to form the nucleosome, a structure responsible for regulating genes and condensing DNA strands to fit into the cell's nucleus. Researchers once thought that nucleosomes regulated gene activity through their histone tails (dotted lines), but a 2010 study revealed that the structures' core also plays a role. The finding sheds light on how gene expression is regulated and how abnormal gene regulation can lead to cancer.

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.

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.

Ecteinascidin 743 (ET-743, brand name Yondelis), was discovered and isolated from a sea squirt, Ecteinascidia turbinata, by NIGMS grantee Kenneth Rinehart at the University of Illinois. It was synthesized by NIGMS grantees E.J. Corey and later by Samuel Danishefsky. Multiple versions of this structure are available as entries 2790-2797.

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.
For imagery of both the lateral and overhead view go to 3556.
For imagery of the lateral view go to 3558.
For more information about the illumated area go to 3559.

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. Related to image 3756.

Cell-like compartments that spontaneously emerged from scrambled frog eggs. Endoplasmic reticulum (red) and microtubules (green) are visible. Image created using epifluorescence microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6591, 6592, and 6593.

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

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.

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

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.

The 46 human chromosomes are shown in blue, with the telomeres appearing as white pinpoints. The DNA has already been copied, so each chromosome is actually made up of two identical lengths of DNA, each with its own two telomeres.

This transmission electron micrograph shows sections of mouse sperm tails, or flagella.

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.

In the worm C. elegans, double-stranded RNA made in neurons can silence matching genes in a variety of cell types through the transport of RNA between cells. The head region of three worms that were genetically modified to express a fluorescent protein were imaged and the images were color-coded based on depth. The worm on the left lacks neuronal double-stranded RNA and thus every cell is fluorescent. In the middle worm, the expression of the fluorescent protein is silenced by neuronal double-stranded RNA and thus most cells are not fluorescent. The worm on the right lacks an enzyme that amplifies RNA for silencing. Surprisingly, the identities of the cells that depend on this enzyme for gene silencing are unpredictable. As a result, worms of identical genotype are nevertheless random mosaics for how the function of gene silencing is carried out. For more, see journal article and press release. Related to image 6532.

In many animals, the egg cell develops alongside sister cells. These sister cells are called nurse cells in the fruit fly (Drosophila melanogaster), and their job is to “nurse” an immature egg cell, or oocyte. Toward the end of oocyte development, the nurse cells transfer all their contents into the oocyte in a process called nurse cell dumping. This video captures this transfer, showing significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red). Researchers created the video using a confocal laser scanning microscope. Related to image 6753.

Scientists use nuclear magnetic spectroscopy (NMR) to determine the detailed, 3D structures of molecules.

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Researchers crystallized complexes where a CCD-1 molecule and a molecule of the antibiotic cefotaxime were bound together. Then, they shot X-rays at the complexes to determine their structure—a process known as X-ray crystallography. This image shows the X-ray diffraction pattern of a complex.

Related to images 6764, 6766, and 6767.

Fourteen neurons (magenta) in the adult Drosophila brain produce insulin, and fat tissue sends packets of lipids to the brain via the lipoprotein carriers (green). This image was captured using a confocal microscope and shows a maximum intensity projection of many slices.

Related to images 6983, 6984, and 6985.

On the left, a cross-section slice of a rat pancreas cell captured using cryo-electron tomography (cryo-ET). On the right, a 3D, color-coded version of the image highlighting cell structures. Visible features include microtubules (neon-green rods), ribosomes (small yellow circles), and vesicles (dark-blue circles). These features are surrounded by the partially visible endoplasmic reticulum (light blue). The black line at the bottom right of the left image represents 200 nm. Related to image 6607.

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 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 (3 of 4), the Cas9 enzyme cuts both strands of the DNA.

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

Thin, hair-like biological structures called cilia are tiny but mighty. Each one, made up of more than 600 different proteins, works together with hundreds of others in a tightly-packed layer to move like a crowd at a ball game doing "the wave." Their synchronized motion helps sweep mucus from the lungs and usher eggs from the ovaries into the uterus. By controlling how fluid flows around an embryo, cilia also help ensure that organs like the heart develop on the correct side of your body.

A 3D reconstruction, created using cryo-electron microscopy, of an ion channel known as the full-length serotonin receptor in complex with the antinausea drug granisetron (orange). Ion channels are proteins in cell membranes that help regulate many processes.

Haplotypes are combinations of gene variants that are likely to be inherited together within the same chromosomal region. In this example, an original haplotype (top) evolved over time to create three newer haplotypes that each differ by a few nucleotides (red). See image 2567 for a labeled version of this illustration. Featured in The New Genetics.

Microscopy image of tongue. One in a series of two, see image 5811

The parasitic worm that causes schistosomiasis hatches in water and grows up in a freshwater snail, as shown here. Once mature, the worm swims back into the water, where it can infect people through skin contact. Initially, an infected person might have a rash, itchy skin, or flu-like symptoms, but the real damage is done over time to internal organs.

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

The worm Caenorhabditis elegans is a popular laboratory animal because its small size and fairly simple body make it easy to study. Scientists use this small worm to answer many research questions in developmental biology, neurobiology, and genetics. This image, which was taken with transmission electron microscopy (TEM), shows a cross-section through C. elegans, revealing various internal structures.

The image is from a figure in an article published in the journal eLife. There is an annotated version of this graphic at 5760.

Misfolded proteins (green) within mitochondria (red). Related to video 5877.

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."

Stained kidney tissue. The kidney is an essential organ responsible for disposing wastes from the body and for maintaining healthy ion levels in the blood. It also secretes two hormones, erythropoietin (EPO) and calcitriol (a derivative of vitamin D), into the blood. It works like a purifier by pulling break-down products of metabolism, such as urea and ammonium, from the blood stream for excretion in urine. Related to image 3725.