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.

Originally from the waters of India, Nepal, and neighboring countries, zebrafish can now be found swimming in science labs (and home aquariums) throughout the world. This fish is a favorite study subject for scientists interested in how genes guide the early stages of prenatal development (including the developing fin shown here) and in the effects of environmental contamination on embryos.

In this image, green fluorescent protein (GFP) is expressed where the gene sox9b is expressed. Collagen (red) marks the fin rays, and DNA, stained with a dye called DAPI, is in blue. sox9b plays many important roles during development, including the building of the heart and brain, and is also necessary for skeletal development. At the University of Wisconsin, researchers have found that exposure to contaminants that bind the aryl-hydrocarbon receptor results in the downregulation of sox9b. Loss of sox9b severely disrupts development in zebrafish and causes a life-threatening disorder called campomelic dysplasia (CD) in humans. CD is characterized by cardiovascular, neural, and skeletal defects. By studying the roles of genes such as sox9b in zebrafish, scientists hope to better understand normal development in humans as well as how to treat developmental disorders and diseases.

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

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.

This graphic that resembles a firework was created from a picture of a fruit fly spermatid. This fruit fly spermatid recycles various molecules, including malformed or damaged proteins. Actin filaments (red) in the cell draw unwanted proteins toward a barrel-shaped structure called the proteasome (green clusters), which degrades the molecules into their basic parts for re-use.

During mitosis, spindle microtubules (red) attach to chromosome pairs (blue), directing them to the spindle equator. This midline alignment is critical for equal distribution of chromosomes in the dividing cell. Scientists are interested in how the protein kinase Plk1 (green) regulates this activity in human cells. Image is a volume projection of multiple deconvolved z-planes acquired with a Nikon widefield fluorescence microscope. This image was chosen as a winner of the 2016 NIH-funded research image call. Related to image 5766.

The research that led to this image was funded by NIGMS.

Ovarioles in female insects are tubes in which egg cells (called oocytes) form at one end and complete their development as they reach the other end of the tube. This image, taken with a confocal microscope, shows ovarioles in a very popular lab animal, the fruit fly Drosophila. The basic structure of ovarioles supports very rapid egg production, with some insects (like termites) producing several thousand eggs per day. Each insect ovary typically contains four to eight ovarioles, but this number varies widely depending on the insect species.

Scientists use insect ovarioles, for example, to study the basic processes that help various insects, including those that cause disease (like some mosquitos and biting flies), reproduce very quickly.

Structure of a magnesium transporter protein from an antibiotic-resistant bacterium (Enterococcus faecalis) found in the human gut. Featured as one of the June 2007 Protein Sructure Initiative Structures of the Month.

The HIV capsid is a pear-shaped structure that is made of proteins the virus needs to mature and become infective. The capsid is inside the virus and delivers the virus' genetic information into a human cell. To better understand how the HIV capsid does this feat, scientists have used computer programs to simulate its assembly. This image shows a series of snapshots of the steps that grow the HIV capsid. A model of a complete capsid is shown on the far right of the image for comparison; the green, blue and red colors indicate different configurations of the capsid protein that make up the capsid “shell.” The bar in the left corner represents a length of 20 nanometers, which is less than a tenth the size of the smallest bacterium. Computer models like this also may be used to reconstruct the assembly of the capsids of other important viruses, such as Ebola or the Zika virus. The studies reporting this research were published in Nature Communications and Nature. To learn more about how researchers used computer simulations to track the assembly of the HIV capsid, see this press release from the University of Chicago.

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

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.

This sculpture made of purple and clear glass beads depicts bacteriophage Phi174, a virus that infects bacteria. It rests on a surface that portrays an adaptive landscape, a conceptual visualization. The ridges represent the gene combinations associated with the greatest fitness levels of the virus, as measured by how quickly the virus can reproduce itself. Phi174 is an important model system for studies of viral evolution because its genome can readily be sequenced as it evolves under defined laboratory conditions.

Model of an enzyme, PanB, from Mycobacterium tuberculosis, the bacterium that causes most cases of tuberculosis. This enzyme is an attractive drug target.

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

At the root tips of the mustard plant Arabidopsis thaliana (red), two proteins work together to control the uptake of water and nutrients. When the cell division-promoting protein called Short-root moves from the center of the tip outward, it triggers the production of another protein (green) that confines Short-root to the nutrient-filtering endodermis. The mechanism sheds light on how genes and proteins interact in a model organism and also could inform the engineering of plants.

Cells walk along body surfaces via tiny "feet," called focal adhesions, that connect with the extracellular matrix. See image 2503 for a labeled version of this illustration.

The image visualizes a part of the yeast molecular interaction network. The lines in the network represent connections among genes (shown as little dots) and different-colored networks indicate subnetworks, for instance, those in specific locations or pathways in the cell. Researchers use gene or protein expression data to build these networks; the network shown here was visualized with a program called Cytoscape. By following changes in the architectures of these networks in response to altered environmental conditions, scientists can home in on those genes that become central "hubs" (highly connected genes), for example, when a cell encounters stress. They can then further investigate the precise role of these genes to uncover how a cell's molecular machinery deals with stress or other factors. Related to images 3730 and 3733.

Solution NMR structure of protein target WR41 (left) from C. elegans. Noting the unanticipated structural similarity to the ubiquitin protein (Ub) found in all eukaryotic cells, researchers discovered that WR41 is a Ub-like modifier, ubiquitin-fold modifier 1 (Ufm1), on a newly uncovered ubiquitin-like pathway. Subsequently, the PSI group also determined the three-dimensional structure of protein target HR41 (right) from humans, the E2 ligase for Ufm1, using both NMR and X-ray crystallography.

Fluorescent markers show the interconnected web of tubes and compartments in the endoplasmic reticulum. The protein atlastin helps build and maintain this critical part of cells. The image is from a July 2009 news release.

T cells are white blood cells that are important in defending the body against bacteria, viruses and other pathogens. Each T cell carries proteins, called T-cell receptors, on its surface that are activated when they come in contact with an invader. This activation sets in motion a cascade of biochemical changes inside the T cell to mount a defense against the invasion. Scientists have been interested for some time what happens after a T-cell receptor is activated. One obstacle has been to study how this signaling cascade, or pathway, proceeds inside T cells.

In this video, researchers have created a T-cell receptor pathway consisting of 12 proteins outside the cell on an artificial membrane. The video shows three key steps during the signaling process: phosphorylation of the T-cell receptor (green), clustering of a protein called linker for activation of T cells (LAT) (blue) and polymerization of the cytoskeleton protein actin (red). The findings show that the T-cell receptor signaling proteins self-organize into separate physical and biochemical compartments. This new system of studying molecular pathways outside the cells will enable scientists to better understand how the immune system combats microbes or other agents that cause infection.

To learn more how researchers assembled this T-cell receptor pathway, see this press release from HHMI's Marine Biological Laboratory Whitman Center. Related to image 3787.

Model of aspartoacylase, a human enzyme involved in brain metabolism.

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

These developing mouse nerve cells have a nucleus (yellow) surrounded by a cell body, with long extensions called axons and thin branching structures called dendrites. Electrical signals travel from the axon of one cell to the dendrites of another.

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

Lysosomes have powerful enzymes and acids to digest and recycle cell materials.

These images illustrate a technique combining cryo-electron tomography and super-resolution fluorescence microscopy called correlative imaging by annotation with single molecules (CIASM). CIASM enables researchers to identify small structures and individual molecules in cells that they couldn’t using older techniques.

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 3742.

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 to cause serious disease.

In this video, 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 image 5751.

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.

This delicate, birdlike projection is an immature seed of the Arabidopsis plant. The part in blue shows the cell that gives rise to the endosperm, the tissue that nourishes the embryo. The cell is expressing only the maternal copy of a gene called MEDEA. This phenomenon, in which the activity of a gene can depend on the parent that contributed it, is called genetic imprinting. In Arabidopsis, the maternal copy of MEDEA makes a protein that keeps the paternal copy silent and reduces the size of the endosperm. In flowering plants and mammals, this sort of genetic imprinting is thought to be a way for the mother to protect herself by limiting the resources she gives to any one embryo. Featured in the May 16, 2006, issue of Biomedical Beat.

A cell in metaphase during mitosis: The copied chromosomes align in the middle of the spindle. 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.

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 called xanthophores in the skin of zebrafish; the cells glow (autofluoresce) brightly under light giving the fish skin a shiny, lively appearance. 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, 5756, 5757 and 5758.

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 3397.

This scanning electron microscope (SEM) image shows podocytes--cells in the kidney that play a vital role in filtering waste from the bloodstream--from a patient with chronic kidney disease. This image first appeared in Princeton Journal Watch on October 4, 2013.

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.

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.

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 3744 and 3745.

Shiga toxin (green) is sorted from the endosome into membrane tubules (red), which then pinch off and move to the Golgi apparatus.

Each morning, the nocturnal Hawaiian bobtail squid, Euprymna scolopes, hides from predators by digging into the sand. At dusk, it leaves the sand again to hunt.

Related to image 7010 and 7011.

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.

Genome editing using CRISPR/Cas9 is a rapidly expanding field of scientific research with emerging applications in disease treatment, medical therapeutics and bioenergy, just to name a few. This technology is now being used in laboratories all over the world to enhance our understanding of how living biological systems work, how to improve treatments for genetic diseases and how to develop energy solutions for a better future.

Ionic and covalent bonds hold molecules, like sodium chloride and chlorine gas, together. Hydrogen bonds among molecules, notably involving water, also play an important role in biology. See image 2520 for a labeled version of this illustration. Featured in The Chemistry of Health.

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.

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.

Microtubules (magenta) and tau protein (light blue) in a cell model of tauopathy. Researchers believe that tauopathy—the aggregation of tau protein—plays a role in Alzheimer’s disease and other neurodegenerative diseases. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6889, 6890, and 6891.

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.

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

This color-enhanced image is a scanning electron microscope image of retinal pigment epithelial (RPE) cells derived from human embryonic stem cells. The cells are remarkably similar to normal RPE cells, growing in a hexagonal shape in a single, well-defined layer. This kind of retinal cell is responsible for macular degeneration, the most common cause of blindness. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to image 3287.

This image of a mammalian epithelial cell, captured in metaphase, was the winning image in the high- and super-resolution microscopy category of the 2012 GE Healthcare Life Sciences Cell Imaging Competition. The image shows microtubules (red), kinetochores (green) and DNA (blue). The DNA is fixed in the process of being moved along the microtubules that form the structure of the spindle.

The image was taken using the DeltaVision OMX imaging system, affectionately known as the "OMG" microscope, and was displayed on the NBC screen in New York's Times Square during the weekend of April 20-21, 2013. It was also 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 a small molecule peptide called CVX15.

An anchor cell (red) pushes through the basement membrane (green) that surrounds it. Some cells are able to push through the tough basement barrier to carry out important tasks--and so can cancer cells, when they spread from one part of the body to another. No one has been able to recreate basement membranes in the lab and they're hard to study in humans, so Duke University researchers turned to the simple worm C. elegans. The researchers identified two molecules that help certain cells orient themselves toward and then punch through the worm's basement membrane. Studying these molecules and the genes that control them could deepen our understanding of cancer spread.

RNA incorporated into the CRISPR surveillance complex is positioned to scan across foreign DNA. Cryo-EM density from a 3Å reconstruction is shown as a yellow mesh.