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 6534.

These time series show the heart rates of four different individuals. Automakers use steel scraps to build cars, construction companies repurpose tires to lay running tracks, and now scientists are reusing previously discarded medical data to better understand our complex physiology. Through a website called PhysioNet developed in part by Beth Israel Deaconess Medical Center cardiologist Ary Goldberger, scientists can access complete physiologic recordings, such as heart rate, respiration, brain activity and gait. They then can use free software to analyze the data and find patterns in it. The patterns could ultimately help health care professionals diagnose and treat health conditions like congestive heart failure, sleeping disorders, epilepsy and walking problems. PhysioNet is supported by NIH's National Institute of Biomedical Imaging and Bioengineering as well as by NIGMS.

Stained glomeruli in the kidney. The kidney is an essential organ responsible for disposing wastes from the body and for maintaining healthy ion levels in the blood. It works like a purifier by pulling break-down products of metabolism, such as urea and ammonium, from the bloodstream for excretion in urine. The glomerulus is a structure that helps filter the waste compounds from the blood. It consists of a network of capillaries enclosed within a Bowman's capsule of a nephron, which is the structure in which ions exit or re-enter the blood in the kidney.

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.

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 2534 for an unlabeled version of this illustration. Featured in Medicines By Design.

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.

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.

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.

Each morning, the nocturnal Hawaiian bobtail squid, Euprymna scolopes, hides from predators by digging into the sand. At dusk, it leaves the sand again to hunt.

Related to image 7010 and 7011.

Mosquito larvae with genes edited by CRISPR swimming in water. 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 video optimized the gene-editing tool CRISPR 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 images 6769 and 6770.

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 receptor is shown bound to an antagonist, ML056.

Vibrio fischeri (2 mm in length) is the exclusive symbiotic partner of the Hawaiian bobtail squid, Euprymna scolopes. After this bacterium uses its flagella to swim from the seawater into the light organ of a newly hatched juvenile, it colonizes the host and loses the appendages. This image was taken using a scanning electron microscope.

Astrocytes in the cross section of a human optic nerve head

Related to image 5870.

Many disease-causing microbes manipulate their host’s metabolism and cells for their own ends. Microsporidia—which are parasites closely related to fungi—infect and multiply inside animal cells, and take the rearranging of cells’ interiors to a new level. They reprogram animal cells such that the cells start to fuse, causing them to form long, continuous tubes. As shown in this image of the roundworm Caenorhabditis elegans, microsporidia (dark oval shapes) invaded the worm’s gut cells (long tube; the cell nuclei are shown in red) and have instructed the cells to merge. The cell fusion enables the microsporidia to thrive and propagate in the expanded space. Scientists study microsporidia in worms to gain more insight into how these parasites manipulate their host cells. This knowledge might help researchers devise strategies to prevent or treat infections with microsporidia.

For more on the research into microsporidia, see this news release from the University of California San Diego. Related to images 5777 and 5779.

Learn about basic science, sometimes called “pure” or “fundamental” science, and how it contributes to the development of medical treatments. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

This illustration of an epoxide-opening cascade promoted by water emulates the proposed biosynthesis of some of the Red Tide toxins.

It has been said that gastrulation is the most important event in a person's life. This part of early embryonic development transforms a simple ball of cells and begins to define cell fate and the body axis. In a study published in Science magazine in March 2012, NIGMS grantee Bob Goldstein and his research group studied how contractions of actomyosin filaments in C. elegans and Drosophila embryos lead to dramatic rearrangements of cell and embryonic structure. This research is described in detail in the following article: "Triggering a Cell Shape Change by Exploiting Preexisting Actomyosin Contractions." In these images, myosin (green) and plasma membrane (red) are highlighted at four timepoints in gastrulation in the roundworm C. elegans. The blue highlights in the top three frames show how cells are internalized, and the site of closure around the involuting cells is marked with an arrow in the last frame. See related video 3334.

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.

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

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: image 1047, image 1048, image 1049,  image 1051 and image 1052.

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.

The glial cells (black dots) and nerve cells (brown bands) in this developing fruit fly nerve cord formed normally despite the absence of the SPITZ protein, which blocks their impending suicide. The HID protein, which triggers suicide, is also lacking in this embryo.

The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2537 for other versions of this image. Featured in Medicines By Design.

Scientists recently discovered the full molecular structure of telomerase, an enzyme important to aging and cancer. Within each cell, telomerase maintains the telomeres, or end pieces, of a chromosome, preserving genetic data and extending the life of the cell. In their study, a team from UCLA and UC Berkeley found the subunit p50, shown in red, to be a keystone in the enzyme's structure and function. Featured in the May 16, 2013 issue of Biomedical Beat.

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.

This image integrates the thousands of known molecular and genetic interactions happening inside our bodies using a computer program called Cytoscape. Images like this are known as network wiring diagrams, but Cytoscape creator Trey Ideker somewhat jokingly calls them "hairballs" because they can be so complicated, intricate and hard to tease apart. Cytoscape comes with tools to help scientists study specific interactions, such as differences between species or between sick and diseased cells. Related to 2737.

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.

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.

Actin is an essential protein in a cell's skeleton (cytoskeleton). It forms a dense network of thin filaments in the cell. Here, researchers have used a technique called stochastic optical reconstruction microscopy (STORM) to visualize the actin network in a cell in three dimensions. The actin strands were labeled with a dye called Alexa Fluor 647-phalloidin.  This image appears in a study published by Nature Methods, which reports how researchers use STORM to visualize the cytoskeleton.

A two-dimensional NMR spectrum of a protein, in this case a 2D 1H-15N HSQC NMR spectrum of a 228 amino acid DNA/RNA-binding protein.

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

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.

Hippocampal cells in culture with a neuron in green, showing hundreds of the small protrusions known as dendritic spines. The dendrites of other neurons are labeled in blue, and adjacent glial cells are shown in red.

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.

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.

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.

Learn about how bacteria and viruses differ, how they each can make you sick, and how they can or cannot be treated. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

Human cells with the gene that codes for the protein FIT2 deleted. After an experimental intervention, they are expressing a nonfunctional version of FIT2, shown in green. The lack of functional FIT2 affected the structure of the endoplasmic reticulum (ER), and the nonfunctional protein clustered in ER membrane aggregates, seen as large bright-green spots. Lipid droplets are shown in red, and the nucleus is visible in gray. This image was captured using a confocal microscope. Related to image 6773.

The human body keeps time with a master clock called the suprachiasmatic nucleus or SCN. Situated inside the brain, it's a tiny sliver of tissue about the size of a grain of rice, located behind the eyes. It sits quite close to the optic nerve, which controls vision, and this means that the SCN "clock" can keep track of day and night. The SCN helps control sleep by coordinating the actions of billions of miniature "clocks" throughout the body. These aren't actually clocks, but rather are ensembles of genes inside clusters of cells that switch on and off in a regular, 24-hour cycle in our physiological day.

A light microscope image of cells 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, two cells have formed after a round of mitosis.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, and 1021.

Solution NMR structure of protein target WR41 (left) from C. elegans. Noting the unanticipated structural similarity to the ubiquitin protein (Ub) found in all eukaryotic cells, researchers discovered that WR41 is a Ub-like modifier, ubiquitin-fold modifier 1 (Ufm1), on a newly uncovered ubiquitin-like pathway. Subsequently, the PSI group also determined the three-dimensional structure of protein target HR41 (right) from humans, the E2 ligase for Ufm1, using both NMR and X-ray crystallography.

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.

Human embryonic stem cells differentiated into dopaminergic neurons, the type that degenerate in Parkinson's disease. Image courtesy of the California Institute for Regenerative Medicine. Related to images 3271 and 3285.

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.

A protein called kinesin (blue) is in charge of moving cargo around inside cells and helping them divide. It's powered by biological fuel called ATP (bright yellow) as it scoots along tube-like cellular tracks called microtubules (gray).

In this video, Rice University scientists used molecular modeling with a mathematical algorithm called AWSEM (for associative memory, water-mediated, structure and energy model) and structural data to analyze how a transcription factor called nuclear factor kappa B (NFkB) is removed from DNA to stop gene activation. AWSEM uses the interacting energies of their components to predict how proteins fold. At the start, the NFkB dimer (green and yellow, in the center) grips DNA (red, to the left), which activates the transcription of genes. IkB (blue, to the right), an inhibitor protein, stops transcription when it binds to NFkB and forces the dimer to twist and release its hold on DNA. The yellow domain at the bottom of IkB is the PEST domain, which binds first to NFkB. For more details about this mechanism called molecular stripping, see here.

CellPack image of the H1N1 influenza virus, with hemagglutinin and neuraminidase glycoproteins in green and red, respectively, on the outer envelope (white); matrix protein in gray, and ribonucleoprotein particles inside the virus in red and green. Related to image 6356.

This 2-hour-old fly embryo already has a blueprint for its formation, and the process for following it is so precise that the difference of just a few key molecules can change the plans. Here, blue marks a high concentration of Bicoid, a key signaling protein that directs the formation of the fly's head. It also regulates another important protein, Hunchback (green), that further maps the head and thorax structures and partitions the embryo in half (red is DNA). The yellow dots overlaying the embryo plot the concentration of Bicoid versus Hunchback proteins within each nucleus. The image illustrates the precision with which an embryo interprets and locates its halfway boundary, approaching limits set by simple physical principles. This image was a finalist in the 2008 Drosophila Image Award.