This fruit fly expresses green fluorescent protein (GFP) in the same pattern as the period gene, a gene that regulates circadian rhythm and is expressed in all sensory neurons on the surface of the fly.

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.

Kinases are enzymes that add phosphate groups (red-yellow structures) to proteins (green), assigning the proteins a code. In this reaction, an intermediate molecule called ATP (adenosine triphosphate) donates a phosphate group from itself, becoming ADP (adenosine diphosphate). See image 2535 for a labeled version of this illustration. Featured in Medicines By Design.

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

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6586, 6591, 6592, and 6593.

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

For thousands of years, Chinese herbalists have treated malaria using Chang Shan, a root extract from a type of hydrangea that grows in Tibet and Nepal. Recent studies have suggested Chang Shan can also reduce scar formation, treat multiple sclerosis and even slow cancer progression.

Model of an enzyme, PanC, that is involved in the last step of vitamin B5 biosynthesis in Mycobacterium tuberculosis. PanC is essential for the growth of M. tuberculosis, which causes most cases of tuberculosis, and is therefore a potential drug target.

Image showing rhabdomeres (red), the light-sensitive structures in the fruit fly retina, and rhodopsin-4 (blue), a light-sensing molecule.

Normal mice, like the B6 breed pictured on the left, develop scars when their ears are pierced. The Murphy Roths Large (MRL) mice pictured on the right can grow back lost ear tissue thanks to an inactive version of the p21 gene. When researchers knocked out that same gene in other mouse breeds, their ears also healed completely without scarring. Journal Article: Clark, L.D., Clark, R.K. and Heber-Katz, E. 1998. A new murine model for mammalian wound repair and regeneration. Clin Immunol Immunopathol 88: 35-45.

To simulate the consequences of disrupting bacterial cell-to-cell communication, called quorum sensing, in the crypts (small chambers within the colon), the researchers experimented with an inhibitor molecule (i.e., antagonist) to turn off quorum sensing in methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant strain of bacteria that often causes human infections. In this experiment, a medium promoting bacterial growth flows through experimental chambers mimicking the colon environment. The chambers on the right contained no antagonist. In the left chambers, after being added to the flowing medium, the quorum-sensing-inhibiting molecules quickly spread throughout the crevices, inactivating quorum sensing and reducing colonization. These results suggest a potential strategy for addressing MRSA virulence via inhibitors of bacterial communication. You can read more about this research here.

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Here, researchers crystallized bound pairs of CCD-1 molecules and molecules of the antibiotic cefotaxime. This enabled their structure to be studied using X-ray crystallography.

Related to images 6765, 6766, and 6767.

These mitochondria (red) are from the heart muscle cell of a rat. Mitochondria have an inner membrane that folds in many places (and that appears here as striations). This folding vastly increases the surface area for energy production. Nearly all our cells have mitochondria. Related to image 3664.

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

This photograph shows a panoramic view of HeLa cells, a cell line many researchers use to study a large variety of important research questions. The cells' nuclei containing the DNA are stained in blue and the cells' cytoskeletons in gray.

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 video illustrates the structure of doublet microtubules, which contain 451 protein chains that were mapped using cryo-electron microscopy. Image can be found here 6548.

Pigment cells are cells that give skin its color. In fishes and amphibians, like frogs and salamanders, pigment cells are responsible for the characteristic skin patterns that help these organisms to blend into their surroundings or attract mates. The pigment cells are derived from neural crest cells, which are cells originating from the neural tube in the early embryo. Investigating pigment cell formation and migration in animals helps answer important fundamental questions about the factors that control pigmentation in the skin of animals, including humans. This image shows a pigment cell from zebrafish at high resolution. Related to images 5755, 5756, 5757 and 5758.

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.

Model of a major secreted protein of unknown function, which is only found in mycobacteria, the class of bacteria that causes tuberculosis. Based on structural similarity, this protein may be involved in host-bacterial interactions.

Vibrio fischeri cells (~ 2 mm), labeled with green fluorescent protein (GFP), passing through a very narrow bottleneck in the tissues (red) of the Hawaiian bobtail squid, Euprymna scolopes, on the way to the crypts where the symbiont population resides. This image was taken using a confocal fluorescence microscope.

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 2542 for a labeled version of this illustration. Featured in The New Genetics.

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 images show three stages of cell division in Xenopus XL177 cells, which are derived from tadpole epithelial cells. They are (from top): metaphase, anaphase and telophase. The microtubules are green and the chromosomes are blue. Related to 3443.

Disassembly of vasculature and reassembly after addition and then washout of 250 µM TBZ in kdr:GFP frogs. Related to images 3403 and 3404.

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.

Crystal structure of oligoendopeptidase F, a protein slicing enzyme from Bacillus stearothermophilus, a bacterium that can cause food products to spoil. The crystal was formed using a microfluidic capillary, a device that enables scientists to independently control the parameters for protein crystal nucleation and growth. Featured as one of the July 2007 Protein Structure Initiative Structures of the Month.

A replica of a human retina grown from stem cells. It shows rod photoreceptors (nerve cells responsible for dark vision) in green and red/green cones (nerve cells responsible for red and green color vision) in red. The cell nuclei are stained blue. This image was captured using a confocal microscope.

Developing spermatids (precursors of mature sperm cells) begin as small, round cells and mature into long-tailed, tadpole-shaped ones. In the sperm cell's head is the cell nucleus; in its tail is the power to outswim thousands of competitors to fertilize an egg. As seen in this microscopy image, fruit fly spermatids start out as groups of interconnected cells. A small lipid molecule called PIP2 helps spermatids tell their heads from their tails. Here, PIP2 (red) marks the nuclei and a cell skeleton-building protein called tubulin (green) marks the tails. When PIP2 levels are too low, some spermatids get mixed up and grow with their heads at the wrong end. Because sperm development is similar across species, studies in fruit flies could help researchers understand male infertility in humans.

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 the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon green), ribosomes (small pale-yellow circles), and lysosomes (large yellowish-green circles). Black line (bottom right of the left image) represents 200 nm. This image is a still from video 6609.

Living primary mouse embryonic fibroblasts. Mitochondria (green) stained with the mitochondrial membrane potential indicator, rhodamine 123. Nuclei (blue) are stained with DAPI. Caption from a November 26, 2012 news release from U Penn (Penn Medicine).

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

This pig cell is in the process of dividing. The chromosomes (purple) have already replicated and the duplicates are being pulled apart by fibers of the cell skeleton known as microtubules (green). Studies of cell division yield knowledge that is critical to advancing understanding of many human diseases, including cancer and birth defects.

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

Shortly after a pregnant woman gives birth, her breasts start to secrete milk. This process is triggered by hormonal and genetic cues, including the protein Elf5. Scientists discovered that Elf5 also has another job--it staves off cancer. Early in the development of breast cancer, human breast cells often lose Elf5 proteins. Cells without Elf5 change shape and spread readily--properties associated with metastasis. This image shows cells in the mouse mammary gland that are lacking Elf5, leading to the overproduction of other proteins (red) that increase the likelihood of metastasis.

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.

Researchers use cluster analysis to study protein shape and function. Each green circle represents one potential shape of the protein mitoNEET. The longer the blue line between two circles, the greater the differences between the shapes. Most shapes are similar; they fall into three clusters that are represented by the three images of the protein. From a Rice University news release. Graduate student Elizabeth Baxter and Patricia Jennings, professor of chemistry and biochemistry at UCSD, collaborated with José Onuchic, a physicist at Rice University, on this work.

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 2557 for a labeled version of this illustration. Featured in The New Genetics.

In this image, recombinant probes known as FingRs (Fibronectin Intrabodies Generated by mRNA display) were expressed in a cortical neuron, where they attached fluorescent proteins to either PSD95 (green) or Gephyrin (red). PSD-95 is a marker for synaptic strength at excitatory postsynaptic sites, and Gephyrin plays a similar role at inhibitory postsynaptic sites. Thus, using FingRs it is possible to obtain a map of synaptic connections onto a particular neuron in a living cell in real time.

Three C. elegans, tiny roundworms, with a ribosomal protein glowing red and muscle fibers glowing green. Researchers used these worms to study a molecular pathway that affects aging. The ribosomal protein is involved in protein translation and may play a role in dietary restriction-induced longevity. Image created using confocal microscopy.
View single roundworm here 6581.
View closeup of roundworms here 6583.

Researchers have learned much of what they know about membranes by constructing artificial membranes in the laboratory. In artificial membranes, different lipids separate from each other based on their physical properties, forming small islands called lipid rafts.

A whole yeast (Saccharomyces cerevisiae) cell viewed by X-ray microscopy. Inside, the nucleus and a large vacuole (red) are visible.

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

A rendering of an activity biosensor image overlaid with a cell-centered frame of reference used for image analysis of signal transduction. This is an example of NIH-supported research on single-cell analysis. Related to 2798 , 2799, 2800, 2801 and 2803.

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.

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.

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.

What looks like a Native American dream catcher is really a network of social interactions within a community. The red dots along the inner and outer circles represent people, while the different colored lines represent direct contact between them. All connections originate from four individuals near the center of the graph. Modeling social networks can help researchers understand how diseases spread.

What looks a little like distant planets with some mysterious surface features are actually assemblies of proteins normally found in the cell's nucleolus, 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 photo of nucleolus proteins in the eggs of a commonly used lab animal, the frog Xenopus laevis, shows each of the nucleolus compartments (the granular component is shown in red, the fibrillarin in yellow-green, and the fibrillar center in blue). The researchers have found that these compartments 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, video 3791 and image 3793.

A crystal of bacterial glucose isomerase protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

Inside the fertilized egg cell of a fruit fly, we see a type of myosin (related to the protein that helps muscles contract) made to glow by attaching a fluorescent protein. After fertilization, the myosin proteins are distributed relatively evenly near the surface of the embryo. The proteins temporarily vanish each time the cells' nuclei--initially buried deep in the cytoplasm--divide. When the multiplying nuclei move to the surface, they shift the myosin, producing darkened holes. The glowing myosin proteins then gather, contract, and start separating the nuclei into their own compartments.

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

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.

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.