This image shows the extracellular matrix (ECM) on the surface of a soleus (lower calf) muscle in light brown and blood vessels in pink. Near the bottom of the photo, a vessel is opened up to reveal red blood cells. Scientists know less about the ECM in muscle than in other tissues, but it's increasingly clear that the ECM is critical to muscle function, and disruption of the ECM has been associated with many muscle disorders. The ECM in muscles stores and releases growth factors, suggesting that it might play a role in cellular communication.

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

These ripples of color represent the outer membrane of the nucleus inside an astrocyte, a star-shaped cell inside the brain. Some proteins (green) act as keys to unlock other proteins (red) that form gates to let small molecules in and out of the nucleus (blue). Visualizing these different cell components at the boundary of the astrocyte nucleus enables researchers to study the molecular and physiological basis of neurological disorders, such as hydrocephalus, a condition in which too much fluid accumulates in the brain, and scar formation in brain tissue leading to abnormal neuronal activity affecting learning and memory. Scientists have now identified a pathway may be common to many of these brain diseases and begun to further examine it to find ways to treat certain brain diseases and injuries.

A cell in prometaphase during mitosis: The nuclear membrane breaks apart, and the spindle starts to interact with the chromosomes. 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.

Centrioles (green) anchor cilia (red), which project on the surface of pharynx cells of the freshwater planarian Schmidtea mediterranea. Centrioles require cellular structures called centrosomes for assembly in other animal species, but this flatworm known for its regenerative ability was unexpectedly found to lack centrosomes. From a Stowers University news release.

Proteins are made of amino acids hooked end-to-end like beads on a necklace. To become active, proteins must twist and fold into their final, or "native," conformation. A protein's final shape enables it to accomplish its function. Featured in The Structures of Life.

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). In ARPC3-/- fibroblast cells, mDia1 is localized at the tips of the filopodia-like structures. Related to images 3328, 3329, 3330, 3332, and 3333.

Cilia (cilium in singular) are complex molecular machines found on many of our cells. One component of cilia is the doublet microtubule, a major part of cilia’s skeletons that give them support and shape. This animated image is a partial model of a doublet microtubule’s structure based on cryo-electron microscopy images. Video can be found here 6549.

A cancer cell with three nuclei, shown in turquoise. The abnormal number of nuclei indicates that the cell failed to go through cell division, probably more than once. Mitochondria are shown in yellow, and a protein of the cell’s cytoskeleton appears in red. This video was captured using a confocal microscope.

The structure of the pore-forming protein VDAC-1 from humans. This molecule mediates the flow of products needed for metabolism--in particular the export of ATP--across the outer membrane of mitochondria, the power plants for eukaryotic cells. VDAC-1 is involved in metabolism and the self-destruction of cells--two biological processes central to health.

Related to images 2491, 2494, and 2488.

The receptor is shown bound to an inverse agonist, doxepin.

Many researchers use the mouse (Mus musculus) as a model organism to study mammalian biology. Mice carry out practically all the same life processes as humans and, because of their small size and short generation times, are easily raised in labs. Scientists studying a certain cellular activity or disease can choose from tens of thousands of specially bred strains of mice to select those prone to developing certain tumors, neurological diseases, metabolic disorders, premature aging, or other conditions.

Microtubules (magenta) and tau protein (light blue) in a cell model of tauopathy. Researchers believe that tauopathy—the aggregation of tau protein—plays a role in Alzheimer’s disease and other neurodegenerative diseases. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6889, 6890, and 6891.

Microfluidic chips have many uses in biology labs. The one shown here was used by bioengineers to study bacteria, allowing the researchers to synchronize their fluorescing so they would blink in unison. Related to images 3266 and 3268. From a UC San Diego news release, "Researchers create living 'neon signs' composed of millions of glowing bacteria."

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

When the heat shock protein hsp33 is folded, it is inactive and contains a zinc ion, stabilizing the redox sensitive domain (orange). In the presence of an environmental stressor, the protein releases the zinc ion, which leads to the unfolding of the redox domain. This unfolding causes the chaperone to activate by reaching out its "arm" (green) to protect other proteins.

Insects like the fruit fly use an elaborate network of branching tubes called trachea (green) to transport oxygen throughout their bodies. Fruit flies have been used in biomedical research for more than 100 years and remain one of the most frequently studied model organisms. They have a large percentage of genes in common with us, including hundreds of genes that are associated with human diseases.

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

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

A research mentor (Lori Eidson) and student (Nina Waldron, on the microscope) were 2009 members of the BRAIN (Behavioral Research Advancements In Neuroscience) program at Georgia State University in Atlanta. This program is an undergraduate summer research experience funded in part by NIGMS.

Using techniques that took 4 years to design, a team of developmental biologists showed that certain proteins can direct the subdivision of fruit fly and chicken nervous system tissue into the regions depicted here in blue, green, and red. Molecules called bone morphogenetic proteins (BMPs) helped form this fruit fly embryo. While scientists knew that BMPs play a major role earlier in embryonic development, they didn't know how the proteins help organize nervous tissue. The findings suggest that BMPs are part of an evolutionarily conserved mechanism for organizing the nervous system. The National Institute of Neurological Disorders and Stroke also supported this work.

Groups of Staphylococcus aureus bacteria (blue) attached to a microstructured titanium surface (green) that mimics an orthopedic implant used in joint replacement. The attachment of pre-formed groups of bacteria may lead to infections because the groups can tolerate antibiotics and evade the immune system. This image was captured using a scanning electron microscope.

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 6804 and video 6805.

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.

These images show frog cells in interphase. The cells are Xenopus XL177 cells, which are derived from tadpole epithelial cells. The microtubules are green and the chromosomes are blue. Related to 3442.

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.

DNA consists of two long, twisted chains made up of nucleotides. Each nucleotide contains one base, one phosphate molecule, and the sugar molecule deoxyribose. The bases in DNA nucleotides are adenine, thymine, cytosine, and guanine. See image 2541 for an unlabeled version of this illustration. Featured in The New Genetics.

A macrophage—a type of immune cell that engulfs invaders—“eats” and is activated by a “two-faced” Janus particle. The particle is called “two-faced” because each of its two hemispheres is coated with a different type of molecule, shown here in red and cyan. During macrophage activation, a transcription factor tagged with a green fluorescence protein (NF-κB) gradually moves from the cell’s cytoplasm into its nucleus and causes DNA transcription. The distribution of molecules on “two-faced” Janus particles can be altered to control the activation of immune cells. Details on this “geometric manipulation” strategy can be found in the Proceedings of the National Academy of Sciences paper "Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling" by Li et al. and the Scientific Reports paper "Spatial organization of FcγR and TLR2/1 on phagosome membranes differentially regulates their synergistic and inhibitory receptor crosstalk" by Li et al. This video was captured using epi-fluorescence microscopy.

Related to video 6800.

The proteasome is a critical multiprotein complex in the cell that breaks down and recycles proteins that have become damaged or are no longer needed. This movie shows how a protein substrate (red) is bound through its ubiquitin chain (blue) to one of the ubiquitin receptors of the proteasome (Rpn10, yellow). The substrate's flexible engagement region then gets engaged by the AAA+ motor of the proteasome (cyan), which initiates mechanical pulling, unfolding and movement of the protein into the proteasome's interior for cleavage into shorter protein pieces called peptides. During movement of the substrate, its ubiquitin modification gets cleaved off by the deubiquitinase Rpn11 (green), which sits directly above the entrance to the AAA+ motor pore and acts as a gatekeeper to ensure efficient ubiquitin removal, a prerequisite for fast protein breakdown by the 26S proteasome. Related to image 3763.

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.

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 (lateral view).
For imagery of both the lateral and overhead view go to 3556.
For imagery of the overhead view go to 3557.
For more information about the illumated area go to 3559.

The 3D single-molecule super-resolution reconstruction of the entire nuclear lamina in a HeLa cell was acquired using the TILT3D platform. TILT3D combines a tilted light sheet with point-spread function (PSF) engineering to provide a flexible imaging platform for 3D single-molecule super-resolution imaging in mammalian cells.
See 6573 for 3 separate views of this structure.

Planarians are freshwater flatworms that have powerful abilities to regenerate their bodies, which would seem to make them natural model organisms in which to study stem cells. But until recently, scientists had not been able to efficiently find the genes that regulate the planarian stem cell system. In this image, a single stem cell has given rise to a colony of stem cells in a planarian. Proliferating cells are red, and differentiating cells are blue. Quantitatively measuring the size and ratios of these two cell types provides a powerful framework for studying the roles of stem cell regulatory genes in planarians.

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.

This scanning electron microscope (SEM) image shows podocytes--cells in the kidney that play a vital role in filtering waste from the bloodstream--from a patient with chronic kidney disease. This image first appeared in Princeton Journal Watch on October 4, 2013.

RNA incorporated into the CRISPR surveillance complex is positioned to scan across foreign DNA. Cryo-EM density from a 3Å reconstruction is shown as a yellow mesh.

Sugars light up the cells in this jaw of a 3-day-old zebrafish embryo and highlight a scientific first: labeling and tracking the movements of sugar chains called glycans in a living organism. Here, recently produced glycans (red) are on the cell surface while those made earlier in development (green) have migrated into the cells. In some areas, old and new glycans mingle (yellow). A better understanding of such traffic patterns could shed light on how organisms develop and may uncover markers for disease, such as cancer. Featured in the May 21, 2008 of Biomedical Beat.

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.

The structure of a gene-regulating zinc finger protein bound to DNA.

This 1 1/2-minute video animation was produced for chemical biologist Stuart Schreiber's lab page. The animation shows how diverse chemical structures can be produced in the lab.

Model of an enzyme, PanB, from Mycobacterium tuberculosis, the bacterium that causes most cases of tuberculosis. This enzyme is an attractive drug target.

To become products, reactants must overcome an energy hill. See image 2526 for a labeled version of this illustration. Featured in The Chemistry of Health.

Moving protein or other molecules to specific cells to treat or examine them has been a major biological challenge. Scientists have now developed a technique for delivering chemicals to individual cells. The approach involves gold nanowires that, for example, can carry tumor-killing proteins. The advance was possible after researchers developed electric tweezers that could manipulate gold nanowires to help deliver drugs to single cells.

This movie shows the manipulation of the nanowires for drug delivery to a single cell. To learn more about this technique, see this post in the Computing Life series.

The proteasome is a critical multiprotein complex in the cell that breaks down and recycles proteins that have become damaged or are no longer needed. This illustration shows a protein substrate (red) that is bound through its ubiquitin chain (blue) to one of the ubiquitin receptors of the proteasome (Rpn10, yellow). The substrate's flexible engagement region gets engaged by the AAA+ motor of the proteasome (cyan), which initiates mechanical pulling, unfolding and movement of the protein into the proteasome's interior for cleavage into small shorter protein pieces called peptides. During movement of the substrate, its ubiquitin modification gets cleaved off by the deubiquitinase Rpn11 (green), which sits directly above the entrance to the AAA+ motor pore and acts as a gatekeeper to ensure efficient ubiquitin removal, a prerequisite for fast protein breakdown by the 26S proteasome. Related to video 3764.

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.

Three-dimensional reconstruction of a tubular matrix in a thin section of the peripheral endoplasmic reticulum between the plasma membranes of the cell.
The endoplasmic reticulum (ER) is a continuous membrane that extends like a net from the envelope of the nucleus outward to the cell membrane. The ER plays several roles within the cell, such as in protein and lipid synthesis and transport of materials between organelles.
Shown here are super-resolution microscopic images of the peripheral ER showing the structure of an ER tubular matrix between the plasma membranes of the cell. See image 5857 for a more detailed view of the area outlined in white in this image. For another view of the ER tubular matrix see image 5855

HIV is a retrovirus, a type of virus that carries its genetic material not as DNA but as RNA. Long before anyone had heard of HIV, researchers in labs all over the world studied retroviruses, tracing out their life cycle and identifying the key proteins the viruses use to infect cells. When HIV was identified as a retrovirus, these studies gave AIDS researchers an immediate jump-start. The previously identified viral proteins became initial drug targets. See images 2514 and 2515 for labeled versions of this illustration. Featured in The Structures of Life.

Leptospira, shown here in green, is a type (genus) of elongated, spiral-shaped bacteria. Infection can cause Weil's disease, a kind of jaundice, in humans.

Established in 1953, the Coriell Institute for Medical Research distributes cell lines and DNA samples to researchers around the world. Shown here are Coriell's cryogenic tanks filled with liquid nitrogen and millions of vials of frozen cells.

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.

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 near the end of a round of mitosis.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1019, and 1021.

An anchor cell (red) pushes through the basement membrane (green) that surrounds it. Some cells are able to push through the tough basement barrier to carry out important tasks--and so can cancer cells, when they spread from one part of the body to another. No one has been able to recreate basement membranes in the lab and they're hard to study in humans, so Duke University researchers turned to the simple worm C. elegans. The researchers identified two molecules that help certain cells orient themselves toward and then punch through the worm's basement membrane. Studying these molecules and the genes that control them could deepen our understanding of cancer spread.