This illustration shows pathogenic bacteria behave like a Trojan horse: switching from antibiotic susceptibility to resistance during infection. Salmonella are vulnerable to antibiotics while circulating in the blood (depicted by fire on red blood cell) but are highly resistant when residing within host macrophages. This leads to treatment failure with the emergence of drug-resistant bacteria.

This image was chosen as a winner of the 2016 NIH-funded research image call, and the research was funded in part by NIGMS.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-out version 5769 of this illustration.

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.

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.

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.

A scanning electron microscope image of an activated mast cell. This image illustrates the interesting topography of the cell membrane, which is populated with receptors. The distribution of receptors may affect cell signaling. This image relates to a July 27, 2009 article in Computing Life.

Damage to each person's genome, often called the "Book of Life," accumulates with time. Such DNA mutations arise from errors in the DNA copying process, as well as from external sources, such as sunlight and cigarette smoke. DNA mutations are known to cause cancer and also may contribute to cellular aging.

A cell in prophase, near the start of mitosis: In the nucleus, chromosomes condense and become visible. In the cytoplasm, the spindle forms. 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.

This image shows two components of the cytoskeleton, microtubules (green) and actin filaments (red), in an endothelial cell derived from a cow lung. The cystoskeleton provides the cell with an inner framework and enables it to move and change shape.

A combination of protein structures determined experimentally and computationally shows us the complete metabolic network of a heat-loving bacterium.

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 microtubule, part of the cell's skeleton, builds and deconstructs.

The marine bacterium Vibrio harveyi glows when near its kind. This luminescence, which results from biochemical reactions, is part of the chemical communication used by the organisms to assess their own population size and distinguish themselves from other types of bacteria. But V. harveyi only light up when part of a large group. This communication, called quorum sensing, speaks for itself here on a lab dish, where more densely packed areas of the bacteria show up blue. Other types of bacteria use quorum sensing to release toxins, trigger disease, and evade the immune system.

The genetic code in DNA is transcribed into RNA, which is translated into proteins with specific sequences. During transcription, nucleotides in DNA are copied into RNA, where they are read three at a time to encode the amino acids in a protein. Many parts of a protein fold as the amino acids are strung together.

See image 2509 for an unlabeled version of this illustration.

Featured in The Structures of Life.

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.

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 separating to form the cores of two new cells.

Related to images 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

A mouse liver glows after being tagged with specially designed infrared-fluorescent protein (IFP). Since its discovery in 1962, green fluorescent protein (GFP) has become an invaluable resource in biomedical imaging. But because of its short wavelength, the light that makes GFP glow doesn't penetrate far in whole animals. So University of California, San Diego cell biologist Roger Tsien--who shared the 2008 Nobel Prize in chemistry for groundbreaking work with GFP--made infrared-fluorescent proteins (IFPs) that shine under longer-wavelength light, allowing whole-body imaging in small animals.

Various views of a zebrafish head with blood vessels shown in purple. Researchers often study zebrafish because they share many genes with humans, grow and reproduce quickly, and have see-through eggs and embryos, which make it easy to study early stages of development.

This video was captured using a light sheet microscope.

Related to image 6934.

The fly fatbody is a nutrient storage and mobilization organ akin to the mammalian liver. The engulfment receptor Draper (green) is located at the cell surface of fatbody cells. The cell nuclei are shown in blue.

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.

Illustration of a sperm, the male reproductive cell.

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.

This image of human red blood cells was obtained with the help of a scanning electron microscope, an instrument that uses a finely focused electron beam to yield detailed images of the surface of a sample.

The Center for Eukaryotic Structural Genomics protein purification facility is responsible for purifying all recombinant proteins produced by the center. The facility performs several purification steps, monitors the quality of the processes, and stores information about the biochemical properties of the purified proteins in the facility database.

The cerebellum is the brain's locomotion control center. Every time you shoot a basketball, tie your shoe or chop an onion, your cerebellum fires into action. Found at the base of your brain, the cerebellum is a single layer of tissue with deep folds like an accordion. People with damage to this region of the brain often have difficulty with balance, coordination and fine motor skills. For a lower magnification, see image 3639.

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

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

These smooth muscle cells were derived from human embryonic stem cells. The nuclei are stained blue, and the proteins of the cytoskeleton are stained green. Image and caption information courtesy of the California Institute for Regenerative Medicine.

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

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.

Gene transcription is a process by which the genetic information encoded in DNA is transcribed into RNA. It's essential for all life and requires the activity of proteins, called transcription factors, that detect where in a DNA strand transcription should start. In eukaryotes (i.e., those that have a nucleus and mitochondria), a protein complex comprising 14 different proteins is responsible for sniffing out transcription start sites and starting the process. This complex, called TFIID, represents the core machinery to which an enzyme, named RNA polymerase, can bind to and read the DNA and transcribe it to RNA. Scientists have used cryo-electron microscopy (cryo-EM) to visualize the TFIID-RNA polymerase-DNA complex in unprecedented detail. In this illustration, TFIID (blue) contacts the DNA and recruits the RNA polymerase (gray) for gene transcription. The start of the transcribed gene is shown with a flash of light. To learn more about the research that has shed new light on gene transcription, see this news release from Berkeley Lab. Related to video 5730.

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 labeled in the image. You can find a high-resolution image without the annotations at image 5759.

The image is from a figure in an article published in the journal eLife.

Like a world of its own, this sphere represents all the known chemical reactions in the E. coli bacterium. The colorful circles on the surface symbolize sets of densely interconnected reactions. The lines between the circles show additional connecting reactions. The shapes inside the circles are landmark molecules, like capital cities on a map, that either act as hubs for many groups of reactions, are highly conserved among species, or both. Molecules that connect far-flung reactions on the sphere are much more conserved during evolution than molecules that connect reactions within a single circle. This statistical cartography could reveal insights about other complex systems, such as protein interactions and gene regulation networks.

The human immunodeficiency virus (HIV), shown here as tiny purple spheres, causes the disease known as AIDS (for acquired immunodeficiency syndrome). HIV can infect multiple cells in your body, including brain cells, but its main target is a cell in the immune system called the CD4 lymphocyte (also called a T-cell or CD4 cell).

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

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, a multivesicular body (the round structure slightly to the right of center) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; the round specks inside the larger round structure) adjacent to the cell's vacuole (below the multivesicular body, shown in darker and more uniform gray).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a color-enhanced version 5767 and image 5769.

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

Time-lapse video of yeast cells undergoing cell division. Nuclear envelopes are shown in green, and spindle pole bodies, which help pull apart copied genetic information, are shown in magenta. This video was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6793, 6794, 6797, 6798, and video 6796.

The cerebellum of a mouse is shown here in cross-section. The cerebellum is the brain's locomotion control center. Every time you shoot a basketball, tie your shoe or chop an onion, your cerebellum fires into action. Found at the base of your brain, the cerebellum is a single layer of tissue with deep folds like an accordion. People with damage to this region of the brain often have difficulty with balance, coordination and fine motor skills. For a higher magnification, see image 3371.

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

In the top snapshots, the brain of a sleep-deprived fruit fly glows orange, marking high concentrations of a synaptic protein called Bruchpilot (BRP) involved in communication between neurons. The color particularly lights up brain areas associated with learning. By contrast, the bottom images from a well-rested fly show lower levels of the protein. These pictures illustrate the results of an April 2009 study showing that sleep reduces the protein's levels, suggesting that such "downscaling" resets the brain to normal levels of synaptic activity and makes it ready to learn after a restful night.

This is an adult flowering Arabidopsis thaliana plant with the inbred designation L-er. Arabidopsis is the most widely used model organism for researchers who study plant genetics.

X-ray crystallography allows researchers to see structures too small to be seen by even the most powerful microscopes. To visualize the arrangement of atoms within molecules, researchers can use the diffraction patterns obtained by passing X-ray beams through crystals of the molecule. This is a common way for solving the structures of proteins. See image 2512 for a labeled version of this illustration. Featured in The Structures of Life.

Model of a protein, antigen 85B, that is the most abundant protein exported by Mycobacterium tuberculosis, which causes most cases of tuberculosis. Antigen 85B is involved in building the bacterial cell wall and is an attractive drug target. Based on its structure, scientists have suggested a new class of antituberculous drugs.

This photograph shows a magnified view of a Drosophila melanogaster pupa in cross section. Compare this normal pupa to one that lacks an important receptor, shown in image 2759.

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 from pearl danio, a 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, 5757 and 5758.

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

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.

A knotted protein from an archaebacterium called Methanobacterium thermoautotrophicam. This organism breaks down waste products and produces methane gas. Protein folding theory previously held that forming a knot was beyond the ability of a protein, but this structure, determined at Argonne's Structural Biology Center, proves differently. Researchers theorize that this knot stabilizes the amino acid subunits of the protein.

This image is a computer-generated model of the approximately 4.2 million atoms of the HIV capsid, the shell that contains the virus' genetic material. Scientists determined the exact structure of the capsid and the proteins that it's made of using a variety of imaging techniques and analyses. They then entered these data into a supercomputer that produced the atomic-level image of the capsid. This structural information could be used for developing drugs that target the capsid, possibly leading to more effective therapies. Related to image 6601.

The photo shows a confocal microscopy image of perineuronal nets (PNNs), which are specialized extracellular matrix (ECM) structures in the brain. The PNN surrounds some nerve cells in brain regions including the cortex, hippocampus and thalamus. Researchers study the PNN to investigate their involvement stabilizing the extracellular environment and forming nets around nerve cells and synapses in the brain. Abnormalities in the PNNs have been linked to a variety of disorders, including epilepsy and schizophrenia, and they limit a process called neural plasticity in which new nerve connections are formed. To visualize the PNNs, researchers labeled them with Wisteria floribunda agglutinin (WFA)-fluorescein. Related to image 3741.