This microscopic image shows a chromatin fiber--a DNA molecule bound to naturally occurring proteins.

The nucleolus is a small but very important protein complex located in the cell's nucleus. It forms on the chromosomes at the location where the genes for the RNAs are that make up the structure of the ribosome, the indispensable cellular machine that makes proteins from messenger RNAs.

However, how the nucleolus grows and maintains its structure has puzzled scientists for some time. It turns out that even though it looks like a simple liquid blob, it's rather well-organized, consisting of three distinct layers: the fibrillar center, where the RNA polymerase is active; the dense fibrillar component, which is enriched in the protein fibrillarin; and the granular component, which contains a protein called nucleophosmin. Researchers have now discovered that this multilayer structure of the nucleolus arises from differences in how the proteins in each compartment mix with water and with each other. These differences let the proteins readily separate from each other into the three nucleolus compartments.

This video of nucleoli in the eggs of a commonly used lab animal, the frog Xenopus laevis, shows how each of the compartments (the granular component is shown in red, the fibrillarin in yellow-green, and the fibrillar center in blue) spontaneously fuse with each other on encounter without mixing with the other compartments.

For more details on this research, see this press release from Princeton. Related to video 3789, image 3792 and image 3793.

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 2454.

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.

Three-dimensional image of misfolded proteins (green) within mitochondria (red). Related to image 5878. Learn more in this press release by The American Association for the Advancement of Science.

Real-time movie of young squids. Squids are often used as research organisms due to having the largest nervous system of any invertebrate, complex behaviors like instantaneous camouflage, and other unique traits.

This video was taken with polychromatic polarization microscope, as described in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak. The color is generated by interaction of white polarized light with the squid’s transparent soft tissue. The tissue works as a living tunable spectral filter, and the transmission band depends on the molecular orientation. When the young squid is moving, the tissue orientation changes, and its color shifts accordingly.

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.

Cells walk along body surfaces via tiny "feet," called focal adhesions, that connect with the extracellular matrix. See image 2502 for an unlabeled version of this illustration.

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.

Our cells are constantly removing and recycling molecular waste. This video shows one way cells process their trash.

Cell mopping up.

Drosophila adult brain showing that an adipokine (fat hormone) generates a response from neurons (aqua) and regulates insulin-producing neurons (red).

Related to images 6982, 6983, and 6984.

Model of the enzyme nicotinic acid phosphoribosyltransferase. This enzyme, from the archaebacterium, Pyrococcus furiosus, is expected to be structurally similar to a clinically important human protein called B-cell colony enhancing factor based on amino acid sequence similarities and structure prediction methods. The structure consists of identical protein subunits, each shown in a different color, arranged in a ring.

The cryo-EM structure of human adenovirus D26 (HAdV-D26) at near atomic resolution (3.7 Å), determined in collaboration with the NRAMM facility*. In difference to archetype HAdV-C5, the HAdV-D26 is a low seroprevalent viral vector, which is being used to generate Ebola virus vaccines.

A typical animal cell, sliced open to reveal a cross-section of organelles.

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.

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.

X-ray crystallography allows researchers to see structures too small to be seen by even the most powerful microscopes. To visualize the arrangement of atoms within molecules, researchers can use the diffraction patterns obtained by passing X-ray beams through crystals of the molecule. This is a common way for solving the structures of proteins. See image 2512 for a labeled version of this illustration. Featured in The Structures of Life.

Watch a cell ripple toward a beam of light that turns on a movement-related protein.

In the absence of the engulfment receptor Draper, salivary gland cells (light blue) persist in the thorax of a developing Drosophila melanogaster pupa. See image 2758 for a cross section of a normal pupa that does express Draper.

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.

A fruit fly ovary, shown here, contains as many as 20 eggs. Fruit flies are not merely tiny insects that buzz around overripe fruit--they are a venerable scientific tool. Research on the flies has shed light on many aspects of human biology, including biological rhythms, learning, memory and neurodegenerative diseases. Another reason fruit flies are so useful in a lab (and so successful in fruit bowls) is that they reproduce rapidly. About three generations can be studied in a single month. Related to image 3607.

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 2566 for an unlabeled version of this illustration. Featured in The New Genetics.

Enzymes speed up chemical reactions by reducing the amount of energy needed for the reactions. The substrate (lactose) binds to the active site of the enzyme (lactase) and is converted into products (sugars).

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 3730 and 3733.

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.

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.

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 separate to form two new cells.

Lab-made liposomes contract where Z rings have gathered together and the constriction forces are greatest (arrows). The top picture shows a liposome, and the bottom picture shows fluorescence from Z rings (arrows) inside the same liposome simultaneously.

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.

Ribonucleic acid (RNA) has a sugar-phosphate backbone and the bases adenine (A), cytosine (C), guanine (G), and uracil (U). Featured in The New Genetics.

See image 2554 for an unlabeled version of this illustration.

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.

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.

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

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 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 eerily glowing blob isn't an alien or a creature from the deep sea--it's a mouse embryo just eight and a half days old. The green shell and core show a protein called Smad4. In the center, Smad4 is telling certain cells to begin forming the mouse's liver and pancreas. Researchers identified a trio of signaling pathways that help switch on Smad4-making genes, starting immature cells on the path to becoming organs. The research could help biologists learn how to grow human liver and pancreas tissue for research, drug testing and regenerative medicine. In addition to NIGMS, NIH's National Institute of Diabetes and Digestive and Kidney Diseases also supported this work.

The cerebellum is the brain's locomotion control center. Found at the base of your brain, the cerebellum is a single layer of tissue with deep folds like an accordion. People with damage to this region of the brain often have difficulty with balance, coordination and fine motor skills.

This image of a mouse cerebellum is part of a collection of such images in different colors and at different levels of magnification from the National Center for Microscopy and Imaging Research (NCMIR). Related to image 5800.

These vials may look like they're filled with colored water, but they really contain nanocrystals reflecting different colors under ultraviolet light. The tiny crystals, made of semiconducting compounds, are called quantum dots. Depending on their size, the dots emit different colors that let scientists use them as a tool for detecting particular genes, proteins, and other biological molecules.

The chemical structure of the morphine molecule

When a molecule arrives at a cell's outer membrane, the membrane creates a pouch around the molecule that protrudes inward. Directed by a protein called dynamin, the pouch then gets pinched off to form a vesicle that carries the molecule to the right place inside the cell. To better understand how dynamin performs its vital pouch-pinching role, researchers determined its structure. Based on the structure, they proposed that a dynamin "collar" at the pouch's base twists ever tighter until the vesicle pops free. Because cells absorb many drugs through vesicles, the discovery could lead to new drug delivery methods.

Like a group of barnacles hanging onto a rock, these human cells hang onto a matrix coated glass slide. Actin stress fibers, stained magenta, and the protein vinculin, stained green, make this adhesion possible. The fibroblast nuclei are stained blue.

The cytoskeleton (green) and DNA (purple) are highlighed in these cells by immunofluorescence.

The G switch allows our bodies to respond rapidly to hormones. See images 2537 and 2538 for labeled versions of this image. Featured in Medicines By Design.

A mouse liver glows after being tagged with specially designed infrared-fluorescent protein (IFP). Since its discovery in 1962, green fluorescent protein (GFP) has become an invaluable resource in biomedical imaging. But because of its short wavelength, the light that makes GFP glow doesn't penetrate far in whole animals. So University of California, San Diego cell biologist Roger Tsien--who shared the 2008 Nobel Prize in chemistry for groundbreaking work with GFP--made infrared-fluorescent proteins (IFPs) that shine under longer-wavelength light, allowing whole-body imaging in small animals.

Colorized scanning electron micrographs progressively zoom in on the eye of a crab larva. In the higher-resolution frames, bacteria are visible on the eye.

Three fruit fly (Drosophila melanogaster) ovarioles (yellow, blue, and magenta) with egg cells visible inside them. Ovarioles are tubes in the reproductive systems of female insects. Egg cells form at one end of an ovariole and complete their development as they reach the other end, as shown in the yellow wild-type ovariole. This process requires an important protein that is missing in the blue and magenta ovarioles. This image was created using confocal microscopy.

More information on the research that produced this image can be found in the Current Biology paper “Gatekeeper function for Short stop at the ring canals of the Drosophila ovary” by Lu et al.

A computer-generated sketch of a DNA origami folded into a flower-and-bird structure. See also related image 3690.

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.

Related to images 1010, 1011, 1012, 1013, 1015, 1016, 1017, 1018, 1019, and 1021.