The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2537 for other versions of this image. Featured in Medicines By Design.

Luciferase-based imaging enables visualization and quantification of internal organs and transplanted cells in live adult zebrafish. In this image, a cardiac muscle-restricted promoter drives firefly luciferase expression (lateral view).
For imagery of both the lateral and overhead view go to 3556.
For imagery of the overhead view go to 3557.
For more information about the illumated area go to 3559.

The cells shown here are fibroblasts, one of the most common cells in mammalian connective tissue. These particular cells were taken from a mouse embryo. Scientists used them to test the power of a new microscopy technique that offers vivid views of the inside of a cell. The DNA within the nucleus (blue), mitochondria (green), and actin filaments in the cellular skeleton (red) are clearly visible.

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

Moving protein or other molecules to specific cells to treat or examine them has been a major biological challenge. Scientists have now developed a technique for delivering chemicals to individual cells. The approach involves gold nanowires that, for example, can carry tumor-killing proteins. The advance was possible after researchers developed electric tweezers that could manipulate gold nanowires to help deliver drugs to single cells.

This movie shows the manipulation of the nanowires for drug delivery to a single cell. To learn more about this technique, see this post in the Computing Life series.

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).

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

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.

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 3607.

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 2511 for an unlabeled version of this illustration. Featured in The Structures of Life.

This image captures the spiral-shaped ovary of an anglerfish in cross-section. Once matured, these eggs will be released in a gelatinous, floating mass. For some species of anglerfish, this egg mass can be up to 3 feet long and include nearly 200,000 eggs.

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

Automated methods using micromachined silicon are used at the Northeast Collaboratory for Structural Genomics to mount protein crystals for X-ray crystallography.

Many researchers use the mouse (Mus musculus) as a model organism to study mammalian biology. Mice carry out practically all the same life processes as humans and, because of their small size and short generation times, are easily raised in labs. Scientists studying a certain cellular activity or disease can choose from tens of thousands of specially bred strains of mice to select those prone to developing certain tumors, neurological diseases, metabolic disorders, premature aging, or other conditions.

A fruit fly (Drosophila melanogaster) egg chamber with microtubules shown in green and actin filaments shown in red. Egg chambers are multicellular structures in fruit flies ovaries that each give rise to a single egg. Microtubules and actin filaments give the chambers structure and shape. This image was captured using a confocal microscope.

More information on the research that produced this image can be found in the Current Biology paper "Gatekeeper function for Short stop at the ring canals of the Drosophila ovary" by Lu et al.

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 receptor is shown bound to an antagonist, eticlopride

2.5Å resolution reconstruction of rabbit muscle aldolase collected on a FEI/Thermo Fisher Titan Krios with energy filter and image corrector.

Animation for the vesicular shuttle model of Golgi transport.

An image of Caenorhabditis elegans, a tiny roundworm, showing internal structures including the intestine, pharynx, and body wall muscle. C. elegans is one of the simplest organisms with a nervous system. Scientists use it to study nervous system development, among other things. This image was captured with a quantitative orientation-independent differential interference contrast (OI-DIC) microscope. The scale bar is 100 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.

On the left, a cross-section slice of a rat pancreas cell captured using cryo-electron tomography (cryo-ET). On the right, a 3D, color-coded version of the image highlighting cell structures. Visible features include microtubules (neon-green rods), ribosomes (small yellow circles), and vesicles (dark-blue circles). These features are surrounded by the partially visible endoplasmic reticulum (light blue). The black line at the bottom right of the left image represents 200 nm. Related to image 6607.

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

In the worm C. elegans, double-stranded RNA made in neurons can silence matching genes in a variety of cell types through the transport of RNA between cells. The head region of three worms that were genetically modified to express a fluorescent protein were imaged and the images were color-coded based on depth. The worm on the left lacks neuronal double-stranded RNA and thus every cell is fluorescent. In the middle worm, the expression of the fluorescent protein is silenced by neuronal double-stranded RNA and thus most cells are not fluorescent. The worm on the right lacks an enzyme that amplifies RNA for silencing. Surprisingly, the identities of the cells that depend on this enzyme for gene silencing are unpredictable. As a result, worms of identical genotype are nevertheless random mosaics for how the function of gene silencing is carried out. For more, see journal article and press release. Related to image 6532.

Like a strand of white pearls, DNA wraps around an assembly of special proteins called histones (colored) to form the nucleosome, a structure responsible for regulating genes and condensing DNA strands to fit into the cell's nucleus. Researchers once thought that nucleosomes regulated gene activity through their histone tails (dotted lines), but a 2010 study revealed that the structures' core also plays a role. The finding sheds light on how gene expression is regulated and how abnormal gene regulation can lead to cancer.

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.

The microtubule severing protein, katanin, localizes to chromosomes and regulates anaphase A in mitosis. The movement of chromosomes on the mitotic spindle requires the depolymerization of microtubule ends. The figure shows the mitotic localization of the microtubule severing protein katanin (green) relative to spindle microtubules (red) and kinetochores/chromosomes (blue). Katanin targets to chromosomes during both metaphase (top) and anaphase (bottom) and is responsible for inducing the depolymerization of attached microtubule plus-ends. This image was a finalist in the 2008 Drosophila Image Award .

A cell in interphase, at the start of mitosis: Chromosomes duplicate, and the copies remain attached to each other. 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.

To become products, reactants must overcome an energy hill. See image 2526 for a labeled version of this illustration. Featured in The Chemistry of Health.

Professor Marc Zimmer's family pets, including these fish, glow in the dark in response to blue light. Featured in the September 2009 issue of Findings.

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.

Neutrophil-like cells (blue) in a microfluidic chip preferentially migrating toward LTB4 over fMLP. A neutrophil is a type of white blood cell that is part of the immune system and helps the body fight infection. Both LTB4 and fMLP are molecules involved in immune response. Microfluidic chips are small devices containing microscopic channels, and they are used in a range of applications, from basic research on cells to pathogen detection. The scale bar in this video is 500μm.

Neuron from a crab showing the cell body (bottom), axon (rope-like extension), and growth cone (top right).

The cone cell of the eye allows you to see in color. Appears in the NIGMS booklet Inside the Cell.

Multicellular yeast called snowflake yeast that researchers created through many generations of directed evolution from unicellular yeast. Cells are connected to one another by their cell walls, shown in blue. Stained cytoplasm (green) and membranes (magenta) show that the individual cells remain separate. This image was captured using spinning disk confocal microscopy.

Related to images 6969 and 6971.

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

Flower development is a carefully orchestrated, genetically programmed process that ensures that the male (stamen) and female (pistil) organs form in the right place and at the right time in the flower. In this image of young Arabidopsis flower buds, the gene SUPERMAN (red) is activated at the boundary between the cells destined to form the male and female parts. SUPERMAN activity prevents the central cells, which will ultimately become the female pistil, from activating the gene APETALA3 (green), which induces formation of male flower organs. The goal of this research is to find out how plants maintain cells (called stem cells) that have the potential to develop into any type of cell and how genetic and environmental factors cause stem cells to develop and specialize into different cell types. This work informs future studies in agriculture, medicine and other fields.

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.

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). ARPC3+/+ fibroblast cells with lamellipodia leading edge. Related to images 3328, 3329, 3330, 3331, and 3333.

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.

Model based on X-ray crystallography of the structure of a small heat shock protein complex from the bacteria, Methanococcus jannaschii. Methanococcus jannaschii is an organism that lives at near boiling temperature, and this protein complex helps it cope with the stress of high temperature. Similar complexes are produced in human cells when they are "stressed" by events such as burns, heart attacks, or strokes. The complexes help cells recover from the stressful event.

This illustration shows vesicle traffic inside a cell. The double membrane that bounds the nucleus flows into the ribosome-studded rough endoplasmic reticulum (purple), where membrane-embedded proteins are manufactured. Proteins are processed and lipids are manufactured in the smooth endoplasmic reticulum (blue) and Golgi apparatus (green). Vesicles that fuse with the cell membrane release their contents outside the cell. The cell can also take in material from outside by having vesicles pinch off from the cell membrane.

T cells engulf and digest cells displaying markers (or antigens) for retroviruses, such as HIV.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. 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 3254 for the related video.

Telophase during mitosis: Nuclear membranes form around each of the two sets of chromosomes, the chromosomes begin to spread out, and the spindle begins to break down. 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.

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 3732.

NMR solution structure of a plant protein that may function in host defense. This protein was expressed in a convenient and efficient wheat germ cell-free system. Featured as the June 2007 Protein Structure Initiative Structure of the Month.

A 20-µm thick section of mouse midbrain. The nerve cells are transparent and weren’t stained. Instead, the color is generated by interaction of white polarized light with the molecules in the cells and indicates their orientation.

The image was obtained with a polychromatic polarizing microscope that shows the polychromatic birefringent image with hue corresponding to the slow axis orientation. More information about the microscopy that produced this image can be found in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak.

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.

Green and yellow fluorescence mark the processes and cell bodies of some C. elegans neurons. Researchers have found that the strategies used by this tiny roundworm to control its motions are remarkably similar to those used by the human brain to command movement of our body parts. From a November 2011 University of Michigan news release.

Video of high-resolution confocal images depicting vimentin immunofluorescence (green) and nuclei (blue) at the edge of a quail embryo yolk. These images were obtained as part of a study to understand cell migration in embryos. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected these images. Related to images 2807 and 2808.

This is a magnified view of an Arabidopsis thaliana leaf eight days after being infected with the pathogen Hyaloperonospora arabidopsidis, which is closely related to crop pathogens that cause 'downy mildew' diseases. It is also more distantly related to the agent that caused the Irish potato famine. The veins of the leaf are light blue; in darker blue are the pathogen's hyphae growing through the leaf. The small round blobs along the length of the hyphae are called haustoria; each is invading a single plant cell to suck nutrients from the cell. Jeff Dangl and other NIGMS-supported researchers investigate how this pathogen and other like it use virulence mechanisms to suppress host defense and help the pathogens grow.

Duplicated pair of chromosomes lined up and ready to cross over.