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), mDia1 (green), and DAPI to visualize the nucleus (blue). mDia1 is localized at the lamellipodia of ARPC3+/+ fibroblast cells. Related to images 3328, 3329, 3331, 3332, and 3333.

This image mostly shows normal cultured epithelial cells expressing green fluorescent protein targeted to the Golgi apparatus (yellow-green) and stained for actin (magenta) and DNA (cyan). The middle cell is an abnormal large multinucleated cell. All the cells in this image have a Golgi but not all are expressing the targeted recombinant fluorescent protein.

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 images 2491, 2494, and 2488.

This image shows the long, branched structures (axons) of nerve cells. Running horizontally across the middle of the photo is an axon wrapped in rings made of actin protein (green), which plays important roles in nerve cells. The image was captured with a powerful microscopy technique that allows scientists to see single molecules in living cells in real time. The technique is called stochastic optical reconstruction microscopy (STORM). It is based on technology so revolutionary that its developers earned the 2014 Nobel Prize in Chemistry. More information about this image can be found in: K. Xu, G. Zhong, X. Zhuang. Actin, spectrin and associated proteins form a periodic cytoskeleton structure in axons. Science 339, 452-456 (2013).

This short video shows a model of the DNA helicase in yeast. This DNA helicase has 11 proteins that work together to unwind DNA during the process of copying it, called DNA replication. Scientists used a technique called cryo-electron microscopy (cryo-EM), which allowed them to study the helicase structure in solution rather than in static crystals. Cryo-EM in combination with computer modeling therefore allows researchers to see movements and other dynamic changes in the protein. The cryo-EM approach revealed the helicase structure at much greater resolution than could be obtained before. The researchers think that a repeated motion within the protein as shown in the video helps it move along the DNA strand. To read more about DNA helicase and this proposed mechanism, see this news release by Brookhaven National Laboratory.

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

Cell-like compartments that spontaneously emerged from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. Image created using confocal microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6586, 6591, 6592.

For videos of cell-like compartments from frog eggs view: 6587, 6588, 6589, and 6590.

The green in this image highlights a protein called TonB, which is produced by many gram-negative bacteria, including those that cause typhoid fever, meningitis and dysentery. TonB lets bacteria take up iron from the host's body, which they need to survive. More information about the research behind this image can be found in a Biomedical Beat Blog posting from August 2013.

Human cells with the gene that codes for the protein FIT2 deleted. After an experimental intervention, they are expressing a nonfunctional version of FIT2, shown in green. The lack of functional FIT2 affected the structure of the endoplasmic reticulum (ER), and the nonfunctional protein clustered in ER membrane aggregates, seen as large bright-green spots. Lipid droplets are shown in red, and the nucleus is visible in gray. This image was captured using a confocal microscope. Related to image 6773.

A computer-generated sketch of a DNA origami folded into a flower-and-bird structure. See also related image 3690.

This is a magnified view of an Arabidopsis thaliana leaf after several days of infection with the pathogen Hyaloperonospora arabidopsidis. The pathogen's blue hyphae grow throughout the leaf. On the leaf's edges, stalk-like structures called sporangiophores are beginning to mature and will release the pathogen's spores. Inside the leaf, the large, deep blue spots are structures called oopsorangia, also full of spores. Compare this response to that shown in Image 2781. Jeff Dangl has been funded by NIGMS to study the interactions between pathogens and hosts that allow or suppress infection.

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also 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: 6588, 6589, and 6590.

Staphylococcus aureus bacteria (green) grouping together upon contact with synovial fluid—a viscous substance found in joints. The formation of groups can help protect the bacteria from immune system defenses and from antibiotics, increasing the likelihood of an infection. This video is a 1-hour time lapse and was captured using a confocal laser scanning microscope.

More information about the research that produced this video can be found in the Journal of Bacteriology paper "In Vitro Staphylococcal Aggregate Morphology and Protection from Antibiotics Are Dependent on Distinct Mechanisms Arising from Postsurgical Joint Components and Fluid Motion" by Staats et al.

Related to images 6803 and 6804.

In this video, Rice University scientists used molecular modeling with a mathematical algorithm called AWSEM (for associative memory, water-mediated, structure and energy model) and structural data to analyze how a transcription factor called nuclear factor kappa B (NFkB) is removed from DNA to stop gene activation. AWSEM uses the interacting energies of their components to predict how proteins fold. At the start, the NFkB dimer (green and yellow, in the center) grips DNA (red, to the left), which activates the transcription of genes. IkB (blue, to the right), an inhibitor protein, stops transcription when it binds to NFkB and forces the dimer to twist and release its hold on DNA. The yellow domain at the bottom of IkB is the PEST domain, which binds first to NFkB. For more details about this mechanism called molecular stripping, see here.

Skins cells were reprogrammed into heart muscle cells. The cells highlighted in green are remaining skin cells. Red indicates a protein that is unique to heart muscle. The technique used to reprogram the skin cells into heart cells could one day be used to mend heart muscle damaged by disease or heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine.

This image capture shows how a single gene, STM, plays a starring role in plant development. This gene acts like a molecular fountain of youth, keeping cells ever-young until it’s time to grow up and commit to making flowers and other plant parts. Because of its ease of use and low cost, Arabidopsis is a favorite model for scientists to learn the basic principles driving tissue growth and regrowth for humans as well as the beautiful plants outside your window. Image captured from video Watch Flowers Spring to Life, featured in the NIH Director's Blog: Watch Flowers Spring to Life.

A mouse's fat cells (red) are shown surrounded by a network of blood vessels (green). Fat cells store and release energy, protect organs and nerve tissues, insulate us from the cold, and help us absorb important vitamins.

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

The 46 human chromosomes are shown in blue, with the telomeres appearing as white pinpoints. The DNA has already been copied, so each chromosome is actually made up of two identical lengths of DNA, each with its own two telomeres.

Three-dimensional reconstruction of a tubular matrix in a thin section of the peripheral endoplasmic reticulum between the plasma membranes of the cell.
The endoplasmic reticulum (ER) is a continuous membrane that extends like a net from the envelope of the nucleus outward to the cell membrane. The ER plays several roles within the cell, such as in protein and lipid synthesis and transport of materials between organelles.
Shown here are super-resolution microscopic images of the peripheral ER showing the structure of an ER tubular matrix between the plasma membranes of the cell. See image 5857 for a more detailed view of the area outlined in white in this image. For another view of the ER tubular matrix see image 5855

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to images 3413, 3414, 3415, 3416, 3418, and 3419.

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.

Enzymes convert substrates into products very quickly. See image 2522 for a labeled version of this illustration. Featured in The Chemistry of Health.

Haplotypes are combinations of gene variants that are likely to be inherited together within the same chromosomal region. In this example, an original haplotype (top) evolved over time to create three newer haplotypes that each differ by a few nucleotides (red). See image 2567 for a labeled version of this illustration. Featured in The New Genetics.

These neural precursor cells were derived from human embryonic stem cells. The neural cell bodies are stained red, and the nuclei are blue. Image and caption information courtesy of the California Institute for Regenerative Medicine.

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.

The small intestine is where most of our nutrients from the food we eat are absorbed into the bloodstream. The walls of the intestine contain small finger-like projections called villi which increase the organ's surface area, enhancing nutrient absorption. It consists of the duodenum, which connects to the stomach, the jejenum and the ileum, which connects with the large intestine. Related to image 3390.

Human metaphase chromosomes are visible with fluorescence in vitro hybridization (FISH). Centromeric alpha satellite DNA (green) are found in the heterochromatin at each centromere. Immunofluorescence with CENP-A (red) shows the centromere-specific histone H3 variant that specifies the kinetochore.

The G switch allows our bodies to respond rapidly to hormones. See images 2537 and 2538 for labeled versions of this image. Featured in Medicines By Design.

Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3745 and 3746.

Scanning electron micrograph of just-divided HeLa cells. Zeiss Merlin HR-SEM. See related images 3519, 3520, 3521, 3522.

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

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.

A mosquito larva with genes edited by CRISPR. The red-orange glow is a fluorescent protein used to track the edits. 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 6770 and video 6771.

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.

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), Arp2 (green), and DAPI to visualize the nucleus (blue). Arp2, a subunit of the Arp2/3 complex, is localized at the lamellipodia leading edge of ARPC3+/+ fibroblast cells. Related to images 3329, 3330, 3331, 3332, and 3333.

In vivo vascular development in kdr:GFP frogs. Related to images 3403 and 3405.

Hepatocytes, like the one shown here, are the most abundant type of cell in the human liver. They play an important role in building proteins; producing bile, a liquid that aids in digesting fats; and chemically processing molecules found normally in the body, like hormones, as well as foreign substances like medicines and alcohol.

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

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.

Zika virus is shown in cross section at center left. On the outside, it includes envelope protein (red) and membrane protein (magenta) embedded in a lipid membrane (light purple). Inside, the RNA genome (yellow) is associated with capsid proteins (orange). The viruses are shown interacting with receptors on the cell surface (green) and are surrounded by blood plasma molecules at the top.

Learn how research organisms, such as fruit flies and mice, can help us understand and treat human diseases. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

This image results from a research project to visualize which regions of the adult fruit fly (Drosophila) brain derive from each neural stem cell. First, researchers collected several thousand fruit fly larvae and fluorescently stained a random stem cell in the brain of each. The idea was to create a population of larvae in which each of the 100 or so neural stem cells was labeled at least once. When the larvae grew to adults, the researchers examined the flies’ brains using confocal microscopy.
With this technique, the part of a fly’s brain that derived from a single, labeled stem cell “lights up.” The scientists photographed each brain and digitally colorized its lit-up area. By combining thousands of such photos, they created a three-dimensional, color-coded map that shows which part of the Drosophila brain comes from each of its ~100 neural stem cells. In other words, each colored region shows which neurons are the progeny or “clones” of a single stem cell. This work established a hierarchical structure as well as nomenclature for the neurons in the Drosophila brain. Further research will relate functions to structures of the brain.

Related to image 5838 and video 5843.

During DNA replication, each strand of the original molecule acts as a template for the synthesis of a new, complementary DNA strand. See image 2543 for an unlabeled version of this illustration. Featured in The New Genetics.

A study using Caulobacter crescentus showed that some bacteria use just-in-time processing, much like that used in industrial delivery, to make the glue that allows them to attach to surfaces, an important step in the infection process for many disease-causing bacteria. In the image shown, this freshwater bacterium has a holdfast at the top and a propelling flagellum at the end. From an Indiana University news release.

Cell-like compartments that spontaneously emerged from scrambled frog eggs. Endoplasmic reticulum (red) and microtubules (green) are visible. Image created using epifluorescence microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6591, 6592, and 6593.

For videos of cell-like compartments from frog eggs view: 6587, 6588, 6589, and 6590.

A Trigonium diatom imaged by a quantitative orientation-independent differential interference contrast (OI-DIC) microscope. Diatoms are single-celled photosynthetic algae with mineralized cell walls that contain silica and provide protection and support. These organisms form an important part of the plankton at the base of the marine and freshwater food chains. The width of this image is 90 μm.

More information about the microscopy that produced this image can be found in the Journal of Microscopy paper “An Orientation-Independent DIC Microscope Allows High Resolution Imaging of Epithelial Cell Migration and Wound Healing in a Cnidarian Model” by Malamy and Shribak.

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 1051.

In SARS-CoV-2, the virus that causes COVID-19, nucleocapsid is a complex molecule with many functional parts. One section folds into an RNA-binding domain, with a groove that grips a short segment of the viral genomic RNA. Another section folds into a dimerization domain that brings two nucleocapsid molecules together. The rest of the protein is intrinsically disordered, forming tails at each end of the protein chain and a flexible linker that connects the two structured domains. These disordered regions assist with RNA binding and orchestrate association of nucleocapsid dimers into larger assemblies that package the RNA in the small space inside virions. Nucleocapsid is in magenta and purple, and short RNA strands are in yellow.

Find these in the RCSB Protein Data Bank: RNA-binding domain (PDB entry 7ACT) and Dimerization domain (PDB entry 6WJI).

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Typical circadian rhythms lead to high energy during the middle of the day (10 a.m. to 1 p.m.) and an afternoon slump. At night, circadian rhythms cause the hormone melatonin to rise, making a person sleepy.

Learn more in NIGMS’ circadian rhythms featured topics page.

See 6612 for the Spanish version of this infographic.

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.

This skyline of New York City was created by “printing” nanodroplets containing yeast (Saccharomyces cerevisiae) onto a large plate. Each dot is a separate yeast colony. As the colonies grew, a picture emerged, creating art. To make the different colors shown here, yeast strains were genetically engineered to produce pigments naturally made by bacteria, fungi, and sea creatures such as coral and sea anemones. Using genes from other organisms to make biological compounds paves the way toward harnessing yeast in the production of other useful molecules, from food to fuels and drugs.