A humorous treatment of the concept of a cycling cell.

The light organ (~0.5 mm across) of a juvenile Hawaiian bobtail squid, Euprymna scolopes, stained blue. The two pairs of ciliated appendages, or “arms,” on the sides of the organ move Vibrio fischeri bacterial cells closer to the two sets of three pores at the base of the arms that each lead to an interior crypt. This image was taken using a confocal fluorescence microscope.

Related to images 7017, 7018, 7019, and 7020.

Microtubules in African green monkey cells. Microtubules are strong, hollow fibers that provide cells with structural support. Here, the microtubules have been color-coded based on their distance from the microscope lens: purple is closest to the lens, and yellow is farthest away. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6889, 6890, and 6892.

Wound healing requires the action of stem cells. In mice that lack the Sept2/ARTS gene, stem cells involved in wound healing live longer and wounds heal faster and more thoroughly than in normal mice. This confocal microscopy image from a mouse lacking the Sept2/ARTS gene shows a tail wound in the process of healing. See more information in the article in Science.

Related to images 3497 and 3500.

Yeast cells with nuclei shown in green and contractile rings shown in magenta. Nuclei store DNA, and contractile rings help cells divide. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6793, 6794, 6797, 6798, and videos 6795 and 6796.

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.

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.

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.

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 2571.

Dynein (green) is a motor protein that “walks” along microtubules (red, part of the cytoskeleton) and carries its cargo along with it. This video was captured through fluorescence microscopy.

The receptor is shown bound to an antagonist, JDTic.

Automated crystal screening systems such as the one shown here are becoming a common feature at synchrotron and other facilities where high-throughput crystal structure determination is being carried out. These systems rapidly screen samples to identify the best candidates for further study.

Blood clots stop bleeding, but they also can cause heart attacks and strokes. A team led by computational biophysicist Klaus Schulten of the University of Illinois at Urbana-Champaign has revealed how a blood protein can give clots their lifesaving and life-threatening abilities. The researchers combined experimental and computational methods to animate fibrinogen, a protein that forms the elastic fibers that enable clots to withstand the force of blood pressure. This simulation shows that the protein, through a series of events, stretches up to three times its length. Adjusting this elasticity could improve how we manage healthful and harmful clots. NIH's National Center for Research Resources also supported this work. Featured in the March 19, 2008, issue of Biomedical Beat.

This image shows an osteosarcoma cell with DNA in blue, energy factories (mitochondria) in yellow, and actin filaments—part of the cellular skeleton—in purple. One of the few cancers that originate in the bones, osteosarcoma is rare, with about a thousand new cases diagnosed each year in the United States.

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

A 3D reconstruction of a transient receptor potential channel called TRPV5 that was created based on cryo-electron microscopy images. TRPV5 is primarily found in kidney cells and is essential for reabsorbing calcium into the blood.

Jellyfish are especially good models for studying the evolution of embryonic tissue layers. Despite being primitive, jellyfish have a nervous system (stained green here) and musculature (red). Cell nuclei are stained blue. By studying how tissues are distributed in this simple organism, scientists can learn about the evolution of the shapes and features of diverse animals.

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

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.

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.

This painting shows a cross section of a small respiratory droplet, like the ones that are thought to transmit SARS-CoV-2, the virus that causes COVID-19. The virus is shown in pink, and the droplet is also filled with molecules that are present in the respiratory tract, including mucins (green), pulmonary surfactant proteins and lipids (blue), and antibodies (tan).

A robot is transferring 96 purification columns to a vacuum manifold for subsequent purification procedures.

A study published in March 2012 used cryo-electron microscopy to determine the structure of the DNA replication origin recognition complex (ORC), a semi-circular, protein complex (yellow) that recognizes and binds DNA to start the replication process. The ORC appears to wrap around and bend approximately 70 base pairs of double stranded DNA (red and blue). Also shown is the protein Cdc6 (green), which is also involved in the initiation of DNA replication. Related to video 3307 that shows the structure from different angles. From a Brookhaven National Laboratory news release, "Study Reveals How Protein Machinery Binds and Wraps DNA to Start Replication."

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.

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 6930 and video 6931.

This illustration represents the early life of a protein—specifically, apomyoglobin—as it is synthesized by a ribosome and emerges from the ribosomal tunnel, which contains the newly formed protein's conformation. The synthesis occurs in the complex swirl of the cell medium, filled with interactions among many molecules. Researchers in Silvia Cavagnero's laboratory are studying the structure and dynamics of newly made proteins and polypeptides using spectroscopic and biochemical techniques.

This image shows the extracellular matrix (ECM) on the surface of a soleus (lower calf) muscle in light brown and blood vessels in pink. Near the bottom of the photo, a vessel is opened up to reveal red blood cells. Scientists know less about the ECM in muscle than in other tissues, but it's increasingly clear that the ECM is critical to muscle function, and disruption of the ECM has been associated with many muscle disorders. The ECM in muscles stores and releases growth factors, suggesting that it might play a role in cellular communication.

Like a map showing heavily traveled roads, this mathematical model of metabolic activity inside an E. coli cell shows the busiest pathway in white. Reaction pathways used less frequently by the cell are marked in red (moderate activity) and green (even less activity). Visualizations like this one may help scientists identify drug targets that block key metabolic pathways in bacteria.

Lysosomes (yellow) and detyrosinated microtubules (light blue). Lysosomes are bubblelike organelles that take in molecules and use enzymes to break them down. Microtubules are strong, hollow fibers that provide structural support to cells. The researchers who took this image found that in epithelial cells, detyrosinated microtubules are a small subset of fibers, and they concentrate lysosomes around themselves. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6890, 6891, and 6892.

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

A red poppy.

In the absence of the engulfment receptor Draper, salivary gland cells (light blue) persist in the thorax of a developing Drosophila melanogaster pupa. See image 2758 for a cross section of a normal pupa that does express Draper.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. This video shows flashing cells as they multiply over the course of more than 12 hours. 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 3253 for a related still image.

The largest human cell (by volume) is the egg. Human eggs are 150 micrometers in diameter and you can just barely see one with a naked eye. In comparison, consider the eggs of chickens...or ostriches!

A 3-D model of the alkaloid serratezomine A shows the molecule's complex ring structure.

On the left, the boundary of a breast tumor (yellow) attaches to collagen fibers that are closest to it (green) using DDR2. On the right, a tumor without DDR2 remains disconnected from the collagen.

Animation for the vesicular shuttle model of Golgi transport.

Individual cells are color-coded based on their identity and signaling activity using a protein circuit technology developed by the Coyle Lab. Just as a radio allows you to listen to an individual frequency, this technology allows researchers to tune into the specific “radio station” of each cell through genetically encoded proteins from a bacterial system called MinDE. The proteins generate an oscillating fluorescent signal that transmits information about cell shape, state, and identity that can be decoded using digital signal processing tools originally designed for telecommunications. The approach allows researchers to look at the dynamics of a single cell in the presence of many other cells.

Related to video 7022.

Cells progress through a cycle that consists of phases for growth (blue, green, yellow) and division (red). Cells become quiescent when they exit this cycle (purple). See image 2499 for a labeled version of this illustration.

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.

These microscopic roundworms, called Caenorhabditis elegans, lack eyes and the opsin proteins used by visual systems to detect colors. However, researchers found that the worms can still sense the color of light in a way that enables them to avoid pigmented toxins made by bacteria. This image was captured using a stereo microscope.

Crystals of fungal lipase 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.

Cells keep time to know when to retire.

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

Human embryonic stem cells were differentiated into cells like those found in the pancreas (blue), which give rise to insulin-producing cells (red). When implanted in mice, the stem cell-derived pancreatic cells can replace the insulin that isn't produced in type 1 diabetes. Image and caption information courtesy of the California Institute for Regenerative Medicine.

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 2541 for an unlabeled version of this illustration. Featured in The New Genetics.

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

The center cluster of cells, colored blue, shows a colony of human embryonic stem cells. These cells, which arise at the earliest stages of development, are capable of differentiating into any of the 220 types of cells in the human body and can provide access to cells for basic research and potential therapies. This image is from the lab of the University of Wisconsin-Madison's James Thomson.

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.

The receptor is shown bound to an antagonist, ML056.

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.