A blue laser beam turns on a protein that helps this human cancer cell move. Responding to the stimulus, the protein, called Rac1, first creates ruffles at the edge of the cell. Then it stretches the cell forward, following the light like a horse trotting after a carrot on a stick. This new light-based approach can turn Rac1 (and potentially many other proteins) on and off at exact times and places in living cells. By manipulating a protein that controls movement, the technique also offers a new tool to study embryonic development, nerve regeneration and cancer.

Rendering of the surface of an endothelial cell; membrane curvature is color coded. This is an example of NIH-supported research on single-cell analysis. Related to 2798 , 2799, 357, 2801, and 2802.

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.

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) and DAPI to visualize the nucleus (blue). In the absence of functional Arp2/3 complex, ARPC3-/- fibroblast cells' leading edge morphology is significantly altered with filopodia-like structures. Related to images 3328, 3329, 3330, 3331, and 3332.

Two models for how material passes through the Golgi apparatus: the vesicular shuttle model and the cisternae maturation model.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to 3413, 3414, 3416, 3417, 3418, and 3419.

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, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

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.

Meiosis is the process whereby a cell reduces its chromosomes from diploid to haploid in creating eggs or sperm. See image 2546 for a labeled version of this illustration. Featured in The New Genetics.

These smooth muscle cells were derived from mouse neural crest stem cells. Red indicates smooth muscle proteins, blue indicates nuclei. Image and caption information courtesy of the California Institute for Regenerative Medicine.

Antibodies are among the most promising therapies for certain forms of cancer, but patients must take them intravenously, exposing healthy tissues to the drug and increasing the risk of side effects. A team of biochemists packed the anticancer antibodies into porous silica particles to deliver a heavy dose directly to tumors in mice.

To splice a human gene into a plasmid, scientists take the plasmid out of an E. coli bacterium, cut the plasmid with a restriction enzyme, and splice in human DNA. The resulting hybrid plasmid can be inserted into another E. coli bacterium, where it multiplies along with the bacterium. There, it can produce large quantities of human protein. See image 2565 for a labeled version of this illustration. Featured in The New Genetics.

A 20-µm thick section of mouse midbrain. The nerve cells are transparent and weren’t stained. Instead, the color is generated by interaction of white polarized light with the molecules in the cells and indicates their orientation.

The image was obtained with a polychromatic polarizing microscope that shows the polychromatic birefringent image with hue corresponding to the slow axis orientation. More information about the microscopy that produced this image can be found in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak.

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.

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.

The human skin cells pictured contain genetic modifications that make them pluripotent, essentially equivalent to embryonic stem cells. A scientific team from the University of Wisconsin-Madison including researchers Junying Yu, James Thomson, and their colleagues produced the transformation by introducing a set of four genes into human fibroblasts, skin cells that are easy to obtain and grow in culture.

Microscopy image of a tongue. One in a series of two, see image 5810

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.

The plasma membrane is a cell's protective barrier. See image 2524 for a labeled version of this illustration. Featured in The Chemistry of Health.

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.

This video shows a controlled outbreak of transmissible avian flu among people living in Thailand. Red indicates areas of infection while blue indicates areas where a combination of control measures were implemented. The video shows how control measures contained the infection in 90 days, before it spread elsewhere.

Speckle microscopy analysis of actin cytoskeleton force. This is an example of NIH-supported research on single-cell analysis. Images in related series; Related to 2799, 2800, 2801, 2802 and 2803.

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 2562 for an unlabeled version of this illustration. Featured in The New Genetics.

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.

Time lapse series shows short dynamin assemblies (not visible) constricting a lipid tube to make a "beads on a string" appearance, then cutting off one of the beads i.e., catalyzing membrane fission). The lipids are fluorescent (artificially colored). Ramachandran R, Pucadyil T.J., Liu Y.W., Acharya S., Leonard M., Lukiyanchuk V., Schmid S.L. 2009. Membrane insertion of the pleckstrin homology domain variable loop 1 is critical for dynamin-catalyzed vesicle scission. Mol Biol Cell. 2009 20:4630-9.

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.

Body organs such as the liver and kidneys process chemicals and toxins. These "target" organs are susceptible to damage caused by these substances. See image 2496 for an unlabeled version of this illustration.

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.

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.

Georgia Tech associate professor Hang Lu holds a microfluidic chip that is part of a system that uses artificial intelligence and cutting-edge image processing to automatically examine large number of nematodes used for genetic research.

The human genome contains much of the information needed for every cell in the body to function. However, different types of cells often need different types of information. Access to DNA is controlled, in part, by how tightly it’s wrapped around proteins called histones to form nucleosomes. The complex shown here, from yeast cells (PDB entry 6Z6P), includes several histone deacetylase (HDAC) enzymes (green and blue) bound to a nucleosome (histone proteins in red; DNA in yellow). The yeast HDAC enzymes are similar to the human enzymes. Two enzymes form a V-shaped clamp (green) that holds the other others, a dimer of the Hda1 enzymes (blue). In this assembly, Hda1 is activated and positioned to remove acetyl groups from histone tails.

Ribosomes manufacture proteins based on mRNA instructions. Each ribosome reads mRNA, recruits tRNA molecules to fetch amino acids, and assembles the amino acids in the proper order.

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.

Antibiotic resistance in microbes is a serious health concern. So researchers have turned their attention to how bacteria undo the action of some antibiotics. Here, scientists set out to find the conditions that help individual bacterial cells survive in the presence of the antibiotic rifampicin. The research team used Mycobacterium smegmatis, a more harmless relative of Mycobacterium tuberculosis, which infects the lung and other organs and causes serious disease.

In this image, genetically identical mycobacteria are growing in a miniature growth chamber called a microfluidic chamber. Using live imaging, the researchers found that individual mycobacteria will respond differently to the antibiotic, depending on the growth stage and other timing factors. The researchers used genetic tagging with green fluorescent protein to distinguish cells that can resist rifampicin and those that cannot. With this gene tag, cells tolerant of the antibiotic light up in green and those that are susceptible in violet, enabling the team to monitor the cells' responses in real time.

To learn more about how the researchers studied antibiotic resistance in mycobacteria, see this news release from Tufts University. Related to video 5752.

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 2513 and 2515 for other versions of this illustration. Featured in The Structures of Life.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. In response to a stressful environment like one lacking food, B. subtilis activates a large set of genes that help it respond to the hardship. Instead of leaving those genes on as previously thought, researchers discovered that the bacteria flip the genes on and off, increasing the frequency of these pulses with increasing stress. See entry 3254 for the related video.

A model of a Geobacter sulfurreducens nanowire created from cryo-electron microscopy images. The bacterium conducts electricity through these nanowires, which are made up of protein and iron-containing molecules.

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.

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.

Just 22 hours after fertilization, this zebrafish embryo is already taking shape. By 36 hours, all of the major organs will have started to form. The zebrafish's rapid growth and see-through embryo make it ideal for scientists studying how organs develop.

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

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.

The receptor is shown bound to a small molecule peptide called CVX15.

Analysis of 68 million-year-old collagen molecule fragments preserved in a T. rex femur confirmed what paleontologists have said for decades: Dinosaurs are close relatives of chickens, ostriches, and to a lesser extent, alligators. A Harvard University research team, including NIGMS-supported postdoctoral research fellow Chris Organ, used sophisticated statistical and computational tools to compare the ancient protein to ones from 21 living species. Because evolutionary processes produce similarities across species, the methods and results may help illuminate other areas of the evolutionary tree. Featured in the May 21, 2008 Biomedical Beat.

Yeast cells that abnormally accumulate cell wall material (blue) at their ends and, when preparing to divide, in their middles. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6794, 6798, and videos 6795 and 6796.

Yeast cells with nuclear envelopes shown in magenta and tubulin shown in light blue. The nuclear envelope defines the borders of the nucleus, which houses DNA. Tubulin is a protein that makes up microtubules—strong, hollow fibers that provide structure to cells and help direct chromosomes during cell division. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6794, 6797, and videos 6795 and 6796.

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. Regions without nuclei formed smaller compartments. 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, 6589, and 6590.

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.

The worm Caenorhabditis elegans is a popular laboratory animal because its small size and fairly simple body make it easy to study. Scientists use this small worm to answer many research questions in developmental biology, neurobiology, and genetics. This image, which was taken with transmission electron microscopy (TEM), shows a cross-section through C. elegans, revealing various internal structures.

The image is from a figure in an article published in the journal eLife. There is an annotated version of this graphic at 5760.

In many animals, the egg cell develops alongside sister cells. These sister cells are called nurse cells in the fruit fly (Drosophila melanogaster), and their job is to “nurse” an immature egg cell, or oocyte. Toward the end of oocyte development, the nurse cells transfer all their contents into the oocyte in a process called nurse cell dumping. This video captures this transfer, showing significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red). Researchers created the video using a confocal laser scanning microscope. Related to image 6753.

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.