Structure of the bacterial antitoxin protein GhoS. GhoS inhibits the production of a bacterial toxin, GhoT, which can contribute to antibiotic resistance. GhoS is the first known bacterial antitoxin that works by cleaving the messenger RNA that carries the instructions for making the toxin. More information can be found in the paper: Wang X, Lord DM, Cheng HY, Osbourne DO, Hong SH, Sanchez-Torres V, Quiroga C, Zheng K, Herrmann T, Peti W, Benedik MJ, Page R, Wood TK. A new type V toxin-antitoxin system where mRNA for toxin GhoT is cleaved by antitoxin GhoS. Nat Chem Biol. 2012 Oct;8(10):855-61. Related to 3428.

This tropical scene, reminiscent of a postcard from Key West, is actually a petri dish containing an artistic arrangement of genetically engineered bacteria. The image showcases eight of the fluorescent proteins created in the laboratory of the late Roger Y. Tsien, a cell biologist at the University of California, San Diego. Tsien, along with Osamu Shimomura of the Marine Biology Laboratory and Martin Chalfie of Columbia University, share the 2008 Nobel Prize in chemistry for their work on green fluorescent protein-a naturally glowing molecule from jellyfish that has become a powerful tool for studying molecules inside living cells.

Jon Lorsch at his swearing in as NIGMS director in August 2013. Also shown are Francis Collins, NIH Director, and Judith Greenberg, former NIGMS Acting Director.

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 difference in how the proteins in each compartment mix with water and with each other. These differences let them 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 3791, image 3792 and image 3793.

A spore from the bacterium Bacillus subtilis shows four outer layers that protect the cell from harsh environmental conditions.

Neurons (green) and glial cells from isolated dorsal root ganglia express COX-2 (red) after exposure to an inflammatory stimulus (cell nuclei are blue). Lawrence Marnett and colleagues have demonstrated that certain drugs selectively block COX-2 metabolism of endocannabinoids -- naturally occurring analgesic molecules -- in stimulated dorsal root ganglia. Featured in the October 20, 2011 issue of Biomedical Beat.

The "epigenetic code" controls gene activity with chemical tags that mark DNA (purple diamonds) and the "tails" of histone proteins (purple triangles). These markings help determine whether genes will be transcribed by RNA polymerase. Genes hidden from access to RNA polymerase are not expressed. See image 2563 for a labeled version of this illustration. Featured in The New Genetics.

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 3792.

Fruit fly (Drosophila melanogaster) ovaries with DNA shown in magenta and actin filaments shown in light blue. This image was captured using a confocal laser scanning microscope.

Related to image 6806.

This video shows 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 videos 2570 and 2572.

This image captures Purkinje cells (red), one of the main types of nerve cell found in the brain. These cells have elaborate branching structures called dendrites that receive signals from other nerve cells.

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

This image shows the structure of the CYP17A1 enzyme (ribbons colored from blue N-terminus to red C-terminus), with the associated heme colored black. The prostate cancer drug abiraterone is colored gray. Cytochrome P450 enzymes bind to and metabolize a variety of chemicals, including drugs. Cytochrome P450 17A1 also helps create steroid hormones. Emily Scott's lab is studying how CYP17A1 could be selectively inhibited to treat prostate cancer. She and graduate student Natasha DeVore elucidated the structure shown using X-ray crystallography. Dr. Scott created the image (both white bg and transparent bg) for the NIGMS image gallery. See the "Medium-Resolution Image" for a PNG version of the image that is transparent.

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 activator cancer cell culture, right, contains a chemical that causes the cells to emit light when in the presence of immune 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 3656. This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

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.

This ribbon drawing of a protein hand drawn and colored by researcher Jane Richardson in 1981 helped originate the ribbon representation of proteins that is now ubiquitous in molecular graphics. The drawing shows the 3-dimensional structure of the protein triose phosphate isomerase. The green arrows represent the barrel of eight beta strands in this structure and the brown spirals show the protein's eight alpha helices. A black and white version of this drawing originally illustrated a review article in Advances in Protein Chemistry, volume 34, titled "Anatomy and Taxonomy of Protein Structures." The illustration was selected as Picture of The Day on the English Wikipedia for November 19, 2009. Other important and beautiful images of protein structures by Jane Richardson are available in her Wikimedia gallery.

A mouse brain that was genetically modified so that subpopulations of its neurons glow. Researchers often study mice because they share many genes with people and can shed light on biological processes, development, and diseases in humans.

This image was captured using a light sheet microscope.

Related to image 6929 and video 6931.

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.

Duplicated pair of chromosomes have exchanged material.

Protein kinases—enzymes that add phosphate groups to molecules—are cancer chemotherapy targets because they play significant roles in almost all aspects of cell function, are tightly regulated, and contribute to the development of cancer and other diseases if any alterations to their regulation occur. Genetic abnormalities affecting the c-Abl tyrosine kinase are linked to chronic myelogenous leukemia, a cancer of immature cells in the bone marrow. In the noncancerous form of the protein, binding of a myristoyl group to the kinase domain inhibits the activity of the protein until it is needed (top left shows the inactive form, top right shows the open and active form). The cancerous variant of the protein, called Bcr-Abl, lacks this autoinhibitory myristoyl group and is continually active (bottom). ATP is shown in green bound in the active site of the kinase.

Find these in the RCSB Protein Data Bank: c-Abl tyrosine kinase and regulatory domains (PDB entry 1OPL) and F-actin binding domain (PDB entry 1ZZP).

The three neurons (red) visible in this image were derived from human embryonic stem cells. Undifferentiated stem cells are green here. Image and caption information courtesy of the California Institute for Regenerative Medicine.

A cropped image of a white poppy. View poppy uncropped here 3424.

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.

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. You can watch a rotating view of the dengue virus surface structure in video 3748.

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. This image shows pigment cells in the fin of pearl danio, a close relative of the popular laboratory animal zebrafish. 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. Related to images 5754, 5755, 5756 and 5758.

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

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.

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.

A fruit fly (Drosophila melanogaster) egg chamber with microtubules shown in green and actin filaments shown in red. Egg chambers are multicellular structures in fruit flies ovaries that each give rise to a single egg. Microtubules and actin filaments give the chambers structure and shape. This image was captured using a confocal microscope.

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 drug's life in the body. Medicines taken by mouth (oral) pass through the liver before they are absorbed into the bloodstream. Other forms of drug administration bypass the liver, entering the blood directly. See 2527 for an unlabeled version of this illustration. Featured in Medicines By Design.

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

Muscles stretch and contract when we walk, and skin splits open and knits back together when we get a paper cut. To study these contractile forces, researchers built a three-dimensional scaffold that mimics tissue in an organism. Researchers poured a mixture of cells and elastic collagen over microscopic posts in a dish. Then they studied how the cells pulled and released the posts as they formed a web of tissue. To measure forces between posts, the researchers developed a computer model. Their findings--which show that contractile forces vary throughout the tissue--could have a wide range of medical applications.

A crystal of bovine milk alpha-lactalbumin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

This animation shows the effect of exposure to hypochlorous acid, which is found in certain types of immune cells, on bacterial proteins. The proteins unfold and stick to one another, leading to cell death.

C. elegans, a tiny roundworm, 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 group of roundworms here 6582.
View closeup of roundworms here 6583.

Crystals of jack bean concanavalin A protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

Industrious V. cholerae bacteria (yellow) tend to thrive in denser biofilms (left) while moochers (red) thrive in weaker biofilms (right). More information about the research behind this image can be found in a Biomedical Beat Blog posting from February 2014.

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.

Glial cells (stained green) in a fruit fly developing embryo have survived thanks to a signaling pathway initiated by neighboring nerve cells (stained red).

Hippocampal neuron from rodent brain with dendrites shown in blue. The hundreds of tiny magenta, green and white dots are the dendritic spines of excitatory synapses.

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.

Flower development is a carefully orchestrated, genetically programmed process that ensures that the male (stamen) and female (pistil) organs form in the right place and at the right time in the flower. In this image of young Arabidopsis flower buds, the gene SUPERMAN (red) is activated at the boundary between the cells destined to form the male and female parts. SUPERMAN activity prevents the central cells, which will ultimately become the female pistil, from activating the gene APETALA3 (green), which induces formation of male flower organs. The goal of this research is to find out how plants maintain cells (called stem cells) that have the potential to develop into any type of cell and how genetic and environmental factors cause stem cells to develop and specialize into different cell types. This work informs future studies in agriculture, medicine and other fields.

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

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 and maintains our circadian rhythm--the regular, 24-hour (or so) cycle of ups and downs in our bodily processes such as hormone levels, blood pressure, and sleepiness. The SCN regulates our circadian rhythm 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 (or so) cycle in our physiological day.

Professor Marc Zimmer's family pets, including these fish, glow in the dark in response to blue light. Featured in the September 2009 issue of Findings.

This image shows a normal fibroblast, a type of cell that is common in connective tissue and frequently studied in research labs. This cell has a healthy skeleton composed of actin (red) and microtubles (green). Actin fibers act like muscles to create tension and microtubules act like bones to withstand compression.

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

Automated methods using micromachined silicon are used at the Northeast Collaboratory for Structural Genomics to mount protein crystals for X-ray crystallography.

Those of us who get sneezy and itchy-eyed every spring or fall may have pollen grains, like those shown here, to blame. Pollen grains are the male germ cells of plants, released to fertilize the corresponding female plant parts. When they are instead inhaled into human nasal passages, they can trigger allergies.

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

A cell in anaphase during mitosis: Chromosomes separate into two genetically identical groups and move to opposite ends of the spindle. 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.