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.

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.

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.

Here, a human HeLa cell (a type of immortal cell line used in laboratory experiments) is undergoing cell division. They come from cervical cancer cells that were obtained in 1951 from Henrietta Lacks, a patient at the Johns Hopkins Hospital. The final stage of division, called cytokinesis, occurs after the genomes—shown in yellow—have split into two new daughter cells. The myosin II is a motor protein shown in blue, and the actin filaments, which are types of protein that support cell structure, are shown in red.

Confocal image showing high levels of the protein vimentin (white) at the edge zone of a quail embryo. Cell nuclei are labeled green. More specifically, this high-magnification (60X) image shows vimentin immunofluorescence in the edge zone (top of image) and inner zone (bottom of image) of a Stage 4 quail blastoderm. Vimentin expression (white) is shown merged with Sytox nuclear labeling (green) at the edge of the blastoderm. A thick vimentin filament runs circumferentially (parallel to the direction of the edge) that appears to delineate the transition between the edge zone and interior zone. Also shown are dense vimentin clusters or foci, which typically appear to be closely associated with edge cell nuclei. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected this image. Related to image 2808 and video 2809.

Model of the mammalian iron enzyme cysteine dioxygenase from a mouse.

A shell from the venomous cone snail Conus omaria, which lives in the Pacific and Indian oceans and eats other snails. University of Utah scientists discovered a new toxin in this snail species' venom, and say it will be a useful tool in designing new medicines for a variety of brain disorders, including Alzheimer's and Parkinson's diseases, depression, nicotine addiction and perhaps schizophrenia.

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.

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

Multiphoton fluorescence image of HeLa cells stained with the actin binding toxin phalloidin (red), microtubules (cyan) and cell nuclei (blue). Nikon RTS2000MP custom laser scanning microscope. See related images 3518, 3519, 3520, 3522.

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. The image shows a side view of the structure of a protein composed of two smaller proteins, called E and M. Each E and M contributes two molecules to the overall protein structure (called a heterotetramer), which is important for assembling and holding together the viral membrane, i.e., the shell that surrounds the genetic material of the dengue virus. The dengue protein's structure has revealed some portions in the protein that might be good targets for developing medications that could be used to combat dengue virus infections. 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.

This image shows mouse fetal heart fibroblast cells. The muscle protein actin is stained red, and the cell nuclei are stained blue. The image was part of a study investigating stem cell-based approaches to repairing tissue damage after a heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. This is the fifthframe in a series of five. The CRISPR system has two components joined together: a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence) and a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA). For an explanation and overview of the CRISPR-Cas9 system, see the NIGMS Biomedical Beat blog entry, Field Focus: Precision Gene Editing with CRISPR and the iBiology video, Genome Engineering with CRISPR-Cas9: Birth of a Breakthrough Technology.

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.

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.

Proteins are 3D structures made up of smaller units. DNA is transcribed to RNA, which in turn is translated into amino acids. Amino acids form a protein strand, which has sections of corkscrew-like coils, called alpha helices, and other sections that fold flat, called beta sheets. The protein then goes through complex folding to produce the 3D structure.

Just as our bodies rely on bones for structural support, our cells rely on a cellular skeleton. In addition to helping cells keep their shape, this cytoskeleton transports material within cells and coordinates cell division. One component of the cytoskeleton is a protein called tubulin, shown here as thin strands.

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

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 lubber grasshopper, found throughout the southern United States, is frequently used in biology classes to teach students about the respiratory system of insects. Unlike mammals, which have red blood cells that carry oxygen throughout the body, insects have breathing tubes that carry air through their exoskeleton directly to where it's needed. This image shows the breathing tubes embedded in the weblike sheath cells that cover developing egg chambers.

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.

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.

A red poppy.

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.

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.

This video simulation shows what an uncontrolled outbreak of transmissible avian flu among people living in Thailand might look like. Red indicates new cases while green indicates areas where the epidemic has finished. The video shows the spread of infection and recovery over 300 days in Thailand and neighboring countries.

Proteins are long chains of amino acids. Each protein has a unique amino acid sequence. It is still a mystery how a protein folds into the proper shape based on its sequence. Scientists hope that one day they can "watch" this folding process for any given protein. The dream has been realized, at least partially, through the use of computer simulation.

Yeast cells with endocytic actin patches (green). These patches help cells take in outside material. When a cell is in interphase, patches concentrate at its ends. During later stages of cell division, patches move to where the cell splits. This image was captured using wide-field microscopy with deconvolution.

Related to images 6791, 6792, 6794, 6797, 6798, and videos 6795 and 6796.

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 image 7021.

Fruit flies are a common model organism for basic medical research.

Force vectors computed from actin cytoskeleton flow. This is an example of NIH-supported research on single-cell analysis. Related to 2798, 2800, 2801, 2802 and 2803.

Planarians are freshwater flatworms that have powerful abilities to regenerate their bodies, which would seem to make them natural model organisms in which to study stem cells. But until recently, scientists had not been able to efficiently find the genes that regulate the planarian stem cell system. In this image, a single stem cell has given rise to a colony of stem cells in a planarian. Proliferating cells are red, and differentiating cells are blue. Quantitatively measuring the size and ratios of these two cell types provides a powerful framework for studying the roles of stem cell regulatory genes in planarians.

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.

These six-month-old axolotls, a kind of salamander, glow green and blue under ultraviolet light. That's because they were genetically modified to make harmless green fluorescent protein, or GFP. Like X-ray vision, GFP lets you see inside the axolotls as they hang out in their aquarium. GFP not only can reveal internal structures in living organisms, but it also can light up specific cells and even proteins within a cell. That allows scientists to identify and track things like cancer cells.

Top view of myelinated axons in a rat spinal root. Myelin is a type of fat that forms a sheath around and thus insulates the axon to protect it from losing the electrical current needed to transmit signals along the axon. The axoplasm inside the axon is shown in pink. Related to 3396.

Arranging exons in different patterns, called alternative splicing, enables cells to make different proteins from a single gene. See image 2553 for a labeled version of this illustration. Featured in The New Genetics.

Novel biosensor system maps the timing and location of Rac protein activation in a living mouse embryo fibroblast.

La sepsis o septicemia es la respuesta fulminante y extrema del cuerpo a una infección. En los Estados Unidos, más de 1.7 millones de personas contraen sepsis cada año. Sin un tratamiento rápido, la sepsis puede provocar daño de los tejidos, insuficiencia orgánica y muerte. El NIGMS apoya a muchos investigadores en su trabajo para mejorar el diagnóstico y el tratamiento de la sepsis.

Vea 6536 para la versión en inglés de esta infografía.

Under the microscope, an E. coli cell lights up like a fireball. Each bright dot marks a surface protein that tells the bacteria to move toward or away from nearby food and toxins. Using a new imaging technique, researchers can map the proteins one at a time and combine them into a single image. This lets them study patterns within and among protein clusters in bacterial cells, which don't have nuclei or organelles like plant and animal cells. Seeing how the proteins arrange themselves should help researchers better understand how cell signaling works.

Model of an enzyme, dUTP pyrophosphatase, from Mycobacterium tuberculosis. Drugs targeted to this enzyme might inhibit the replication of the bacterium that causes most cases of tuberculosis.

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.

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 process involves significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red). This image was captured using a confocal laser scanning microscope. Related to video 6754.

As an egg cell develops, a process called polarization controls what parts ultimately become the embryo's head and tail. This picture shows an egg of the fruit fly Drosophila. Red and green mark two types of signaling proteins involved in polarization. Disrupting these signals can scramble the body plan of the embryo, leading to severe developmental disorders.

Insect brains, like the honeybee brain shown here, are very different in shape from human brains. Despite that, bee and human brains have a lot in common, including many of the genes and neurochemicals they rely on in order to function. The bright-green spots in this image indicate the presence of tyrosine hydroxylase, an enzyme that allows the brain to produce dopamine. Dopamine is involved in many important functions, such as the ability to experience pleasure. This image was captured using confocal microscopy.

Student Christina Hueneke of the Midwest Center for Structural Genomics is overseeing a protein cloning robot. The robot was designed as part of an effort to exponentially increase the output of a traditional wet lab. Part of the center's goal is to cut the average cost of analyzing a protein from $200,000 to $20,000 and to slash the average time from months to days and hours.

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

Like a major city, a cell teems with specialized workers that carry out its daily operations--making energy, moving proteins, or helping with other tasks. Researchers took microscopic pictures of thin layers of a cell and then combined them to make this 3-D image featuring color-coded organelles--the cell's "workers." Using this image, scientists can understand how these specialized components fit together in the cell's packed inner world.

Enzymes convert substrates into products very quickly. See image 2521 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

The three fibers of the cytoskeleton--microtubules in blue, intermediate filaments in red, and actin in green--play countless roles in the cell.

This photograph shows a panoramic view of HeLa cells, a cell line many researchers use to study a large variety of important research questions. The cells' nuclei containing the DNA are stained in blue and the cells' cytoskeletons in gray.

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. Cell nuclei are in blue. Red and orange mark hair follicle stem cells (hair follicle stem cells activate to cause hair regrowth, which indicates healing). See more information in the article in Science.