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, 1049, 1050, 1051 and 1052.

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.

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.

Floral pattern emerging as two bacterial species, motile Acinetobacter baylyi (red) and non-motile Escherichia coli (green), are grown together for 48 hours on 1% agar surface from a small inoculum in the center of a Petri dish.

See 6557 for a photo of this process at 24 hours on 0.75% agar surface.
See 6555 for another photo of this process at 48 hours on 1% agar surface.
See 6556 for a photo of this process at 72 hours on 0.5% agar surface.
See 6550 for a video of this process.

This image shows the hierarchical ontology of genes, cellular components and processes derived from large genomic datasets. From Dutkowski et al. A gene ontology inferred from molecular networks Nat Biotechnol. 2013 Jan;31(1):38-45. Related to 3436.

Analysis of 68 million-year-old collagen molecule fragments preserved in a T. rex femur confirmed what paleontologists have said for decades: Dinosaurs are close relatives of chickens, ostriches, and to a lesser extent, alligators. A Harvard University research team, including NIGMS-supported postdoctoral research fellow Chris Organ, used sophisticated statistical and computational tools to compare the ancient protein to ones from 21 living species. Because evolutionary processes produce similarities across species, the methods and results may help illuminate other areas of the evolutionary tree. Featured in the May 21, 2008 Biomedical Beat.

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.

Using an electrode, researchers apply an electrical pulse onto a piece of muscle tissue affected by Huntington's disease.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to images 3413, 3414, 3415, 3416, 3417, and 3419.

Yeast cells entering mitosis, also known as cell division. The green and magenta dots are two proteins that play important roles in mitosis. They show where the cells will split. This image was captured using wide-field microscopy with deconvolution.

Related to images 6792, 6793, 6794, 6797, 6798, and videos 6795 and 6796.

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.

Two healthy cells (bottom, left) enter into apoptosis (bottom, center) but spring back to life after a fatal toxin is removed (bottom, right; top).

Speckle microscopy analysis of actin cytoskeleton force. This is an example of NIH-supported research on single-cell analysis. Images in related series; Related to 2799, 2800, 2801, 2802 and 2803.

Featured in the March 15, 2012 issue of Biomedical Beat. Related to Hsp33 Figure 2, image 3355.

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 typical animal cell cycle lasts roughly 24 hours, but depending on the type of cell, it can vary in length from less than 8 hours to more than a year. Most of the variability occurs in Gap1. Appears in the NIGMS booklet Inside the Cell.

The structure of a gene-regulating zinc finger protein bound to DNA.

Acetylsalicylate (bottom) is the aspirin of today. Adding a chemical tag called an acetyl group (shaded box, bottom) to a molecule derived from willow bark (salicylate, top) makes the molecule less acidic (and easier on the lining of the digestive tract), but still effective at relieving pain. See image 2530 for a labeled version of this illustration. Featured in Medicines By Design.

The Center for Eukaryotic Structural Genomics protein purification facility is responsible for purifying all recombinant proteins produced by the center. The facility performs several purification steps, monitors the quality of the processes, and stores information about the biochemical properties of the purified proteins in the facility database.

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 3498.

A cancer cell with three nuclei, shown in turquoise. The abnormal number of nuclei indicates that the cell failed to go through cell division, probably more than once. Mitochondria are shown in yellow, and a protein of the cell’s cytoskeleton appears in red. This video was captured using a confocal microscope.

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

In the determination of protein structures by X-ray crystallography, this unique soft (l = 2.29Å) X-ray source is used to collect anomalous scattering data from protein crystals containing light atoms such as sulfur, calcium, zinc and phosphorous. These data can be used to image the protein.

Cross-section of skin anatomy shows layers and different tissue types.

Cell showing overproduction of the ARTS protein (red). ARTS triggers apoptosis, as shown by the activation of caspase-3 (green) a key tool in the cell's destruction. The nucleus is shown in blue. Image is featured in October 2015 Biomedical Beat blog post Cool Images: A Halloween-Inspired Cell Collection.

Nodes of Ranvier are short gaps in the myelin sheath surrounding myelinated nerve cells (axons). Myelin insulates axons, and the node of Ranvier is where the axon is exposed to the extracellular environment, allowing for the transmission of action potentials at these nodes via ion flows between the inside and outside of the axon. The image shows a cross-section through the node, with the surrounding extracellular matrix encasing and supporting the axon shown in cyan.

Crystals of porcine trypsin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

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.

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.

Like a watch wrapped around a wrist, a special enzyme encircles the double helix to repair a broken strand of DNA. Without molecules that can mend such breaks, cells can malfunction, die, or become cancerous. Related to image 2330.

In this image of a stained fruit fly ovary, the ovary is packed with immature eggs (with DNA stained blue). The cytoskeleton (in pink) is a collection of fibers that gives a cell shape and support. The signal-transmitting molecules like STAT (in yellow) are common to reproductive processes in humans. Researchers used this image to show molecular staining and high-resolution imaging techniques to students.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-in version 5767 of this illustration.

Multiphoton fluorescence image of HeLa cells with cytoskeletal microtubules (magenta) and DNA (cyan). Nikon RTS2000MP custom laser scanning microscope. See related images 3518, 3519, 3521, 3522.

An axolotl—a type of salamander—that has been genetically modified so that its developing nervous system glows purple and its Schwann cell nuclei appear light blue. Schwann cells insulate and provide nutrients to peripheral nerve cells. Researchers often study axolotls for their extensive regenerative abilities. They can regrow tails, limbs, spinal cords, brains, and more. The researcher who took this image focuses on the role of the peripheral nervous system during limb regeneration.

This image was captured using a stereo microscope.

Related to images 6927 and 6928.

The 3D single-molecule super-resolution reconstruction of the entire nuclear lamina in a HeLa cell was acquired using the TILT3D platform. TILT3D combines a tilted light sheet with point-spread function (PSF) engineering to provide a flexible imaging platform for 3D single-molecule super-resolution imaging in mammalian cells.
See 6573 for 3 separate views of this structure.

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 by Malamy and Shribak.

This time-lapse movie shows that bacterial communities called biofilms can create blockages that prevent fluid flow in devices such as stents and catheters over a period of about 56 hours. This video was featured in a news release from Princeton University.