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.

A white poppy. View cropped image of a poppy here 3423.

The endoplasmic reticulum comes in two types: Rough ER is covered with ribosomes and prepares newly made proteins; smooth ER specializes in making lipids and breaking down toxic molecules.

To better understand cell movements in developing embryos, researchers isolated cells from early zebrafish embryos and grew them as clusters. Provided with the right signals, the clusters replicated some cell movements seen in intact embryos. Each line in this image depicts the movement of a single cell. The image was created using time-lapse confocal microscopy. Related to video 6776.

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.

Time lapse series shows short dynamin assemblies (not visible) constricting a lipid tube to make a "beads on a string" appearance, then cutting off one of the beads i.e., catalyzing membrane fission). The lipids are fluorescent (artificially colored). Ramachandran R, Pucadyil T.J., Liu Y.W., Acharya S., Leonard M., Lukiyanchuk V., Schmid S.L. 2009. Membrane insertion of the pleckstrin homology domain variable loop 1 is critical for dynamin-catalyzed vesicle scission. Mol Biol Cell. 2009 20:4630-9.

Reactivating telomerase in our cells does not appear to be a good way to extend the human lifespan. Cancer cells reactivate telomerase.

An Arachnoidiscus diatom with a diameter of 190µm. Diatoms are microscopic algae that have cell walls made of silica, which is the strongest known biological material relative to its density. In Arachnoidiscus, the cell wall is a radially symmetric pillbox-like shell composed of overlapping halves that contain intricate and delicate patterns. Sometimes, Arachnoidiscus is called “a wheel of glass.”

This image was taken with the orientation-independent differential interference contrast microscope.

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.

Damage to each person's genome, often called the "Book of Life," accumulates with time. Such DNA mutations arise from errors in the DNA copying process, as well as from external sources, such as sunlight and cigarette smoke. DNA mutations are known to cause cancer and also may contribute to cellular aging.

Related to image 5870.

Fourteen neurons (magenta) in the adult Drosophila brain produce insulin, and fat tissue sends packets of lipids to the brain via the lipoprotein carriers (green). This image was captured using a confocal microscope and shows a maximum intensity projection of many slices.

Related to images 6983, 6984, and 6985.

Researchers used fluorescence in situ hybridization (FISH) to confirm the presence of long range DNA-DNA interactions in mouse embryonic stem cells. Here, two loci labeled in green (Oct4) and red that are 13 Mb apart on linear DNA are frequently found to be in close proximity. DNA-DNA colocalizations like this are thought to both reflect and contribute to cell type specific gene expression programs.

An adult Hawaiian bobtail squid, Euprymna scolopes, swimming next to a submerged hand.

Related to image 7010 and video 7012.

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 near the end of a round of mitosis.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1019, and 1021.

Myotonic dystrophy is thought to be caused by the binding of a protein called Mbnl1 to abnormal RNA repeats. In these two images of the same muscle precursor cell, the top image shows the location of the Mbnl1 splicing factor (green) and the bottom image shows the location of RNA repeats (red) inside the cell nucleus (blue). The white arrows point to two large foci in the cell nucleus where Mbnl1 is sequestered with RNA.

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.

A cell in anaphase during mitosis: Chromosomes separate into two genetically identical groups and move to opposite ends 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.

A light organ (~0.5 mm across) of a Hawaiian bobtail squid, Euprymna scolopes, stained blue. At the time of this image, the crypts within the tissues of only one side of the organ had been colonized by green-fluorescent protein-labeled Vibrio fischeri cells, which can be seen here in green. This image was taken using confocal fluorescence microscopy.

Related to images 7016, 7017, 7018, and 7019.

A macrophage—a type of immune cell that engulfs invaders—“eats” and is activated by a “two-faced” Janus particle. The particle is called “two-faced” because each of its two hemispheres is coated with a different type of molecule, shown here in red and cyan. During macrophage activation, a transcription factor tagged with a green fluorescence protein (NF-κB) gradually moves from the cell’s cytoplasm into its nucleus and causes DNA transcription. The distribution of molecules on “two-faced” Janus particles can be altered to control the activation of immune cells. Details on this “geometric manipulation” strategy can be found in the Proceedings of the National Academy of Sciences paper "Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling" by Li et al. and the Scientific Reports paper "Spatial organization of FcγR and TLR2/1 on phagosome membranes differentially regulates their synergistic and inhibitory receptor crosstalk" by Li et al. This video was captured using epi-fluorescence microscopy.

Related to video 6800.

A model of the molecule himastatin overlaid on an image of Bacillus subtilis bacteria. Scientists first isolated himastatin from the bacterium Streptomyces himastatinicus, and the molecule shows antibiotic activity. The researchers who created this image developed a new, more concise way to synthesize himastatin so it can be studied more easily. They also tested the effects of himastatin and derivatives of the molecule on B. subtilis.

More information about the research that produced this image can be found in the Science paper “Total synthesis of himastatin” by D’Angelo et al.

Related to image 6848 and video 6851.

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.

These time series show the heart rates of four different individuals. Automakers use steel scraps to build cars, construction companies repurpose tires to lay running tracks, and now scientists are reusing previously discarded medical data to better understand our complex physiology. Through a website called PhysioNet developed in part by Beth Israel Deaconess Medical Center cardiologist Ary Goldberger, scientists can access complete physiologic recordings, such as heart rate, respiration, brain activity and gait. They then can use free software to analyze the data and find patterns in it. The patterns could ultimately help health care professionals diagnose and treat health conditions like congestive heart failure, sleeping disorders, epilepsy and walking problems. PhysioNet is supported by NIH's National Institute of Biomedical Imaging and Bioengineering as well as by NIGMS.

A genetic disorder of the nervous system, neurofibromatosis causes tumors to form on nerves throughout the body, including a type of tumor called an optic nerve glioma that can result in childhood blindness. The image was used to demonstrate the unique imaging capabilities of one of our newest (at the time) laser scanning microscopes and is of a wildtype (normal) mouse retina in the optic fiber layer. This layer is responsible for relaying information from the retina to the brain and was fluorescently stained to reveal the distribution of glial cells (green), DNA and RNA in the cell bodies of the retinal ganglion neurons (orange) and their optic nerve fibers (red), and actin in endothelial cells surrounding a prominent branching blood vessel (blue). By studying the microscopic structure of normal and diseased retina and optic nerves, we hope to better understand the altered biology of the tissues in these tumors with the prospects of developing therapeutic interventions.

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.

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.

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 highly stressed osteosarcoma cells are shown with a set of green droplet-like structures followed by a second set of magenta droplets. These droplets are composed of fluorescently labeled stress-response proteins, either G3BP or UBQLN2 (Ubiquilin-2). Each protein is undergoing a fascinating process, called phase separation, in which a non-membrane bound compartment of the cytoplasm emerges with a distinct environment from the surrounding cytoplasm. Subsequently, the proteins fuse with like proteins to form larger droplets, in much the same way that raindrops merge on a car’s windshield.

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.

A biofilm is a highly organized community of microorganisms that develops naturally on certain surfaces. These communities are common in natural environments and generally do not pose any danger to humans. Many microbes in biofilms have a positive impact on the planet and our societies. Biofilms can be helpful in treatment of wastewater, for example. This dime-sized biofilm, however, was formed by the opportunistic pathogen Pseudomonas aeruginosa. Under some conditions, this bacterium can infect wounds that are caused by severe burns. The bacterial cells release a variety of materials to form an extracellular matrix, which is stained red in this photograph. The matrix holds the biofilm together and protects the bacteria from antibiotics and the immune system.

Endocytosis is the process by which cells are able to take up membrane and extracellular materials through the formation of a small intracellular bubble, called a vesicle. This process, called membrane budding, is generally by a coating of proteins. This protein coat helps both to deform the membrane and to concentrate specific proteins inside the newly forming vesicle. Clathrin is a coat protein that functions in receptor-mediated endocytosis events at the plasma membrane. This animation shows the process of clathrin-mediated endocytosis. An iron-transport protein called transferrin (blue) is bound to its receptor (purple) on the exterior cell membrane.  Inside the cell, a clathrin cage (shown in white/beige) assembles through interactions with membrane-bound adaptor proteins (green), causing the cell membrane to begin bending. The adaptor proteins also bind to receptors for transferrin, capturing them in the growing vesicle. Molecules of a protein called dynamin (purple) are then recruited to the neck of the vesicle and are involved in separating the membranes of the cell and the vesicle. Soon after the vesicle has budded off the membrane, the clathrin cage is disassembled. This disassembly is mediated by another protein called HSC70 (yellow), and its cofactor protein auxilin (orange).

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.

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.

This illustration represents the early life of a protein—specifically, apomyoglobin—as it is synthesized by a ribosome and emerges from the ribosomal tunnel, which contains the newly formed protein's conformation. The synthesis occurs in the complex swirl of the cell medium, filled with interactions among many molecules. Researchers in Silvia Cavagnero's laboratory are studying the structure and dynamics of newly made proteins and polypeptides using spectroscopic and biochemical techniques.

Model of the enzyme aminopeptidase N from the human pathogen Neisseria meningitidis, which can cause meningitis epidemics. The structure provides insight on the active site of this important molecule.

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.

Bioengineers were able to coax bacteria to blink in unison on microfluidic chips. This image shows a small chip with about 500 blinking bacterial colonies or biopixels. Related to images 3265 and 3268. From a UC San Diego news release, "Researchers create living 'neon signs' composed of millions of glowing bacteria."

For thousands of years, Chinese herbalists have treated malaria using Chang Shan, a root extract from a type of hydrangea that grows in Tibet and Nepal. Recent studies have suggested Chang Shan can also reduce scar formation, treat multiple sclerosis and even slow cancer progression.

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

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.

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.

During development, a zebrafish embryo is transformed from a ball of cells into a recognizable body plan by sweeping convergence and extension cell movements. This process is called gastrulation. Each line in this video represents the movement of a single zebrafish embryo cell over the course of 3 hours. The video was created using time-lapse confocal microscopy. Related to image 6775.

Genes are often interrupted by stretches of DNA (introns, blue) that do not contain instructions for making a protein. The DNA segments that do contain protein-making instructions are known as exons (green). See image 2550 for an unlabeled version of this illustration. Featured in The New Genetics.

A zebrafish embryo. The blue areas are cell bodies, the green lines are blood vessels, and the red glow is blood. This image was created by stitching together five individual images captured with a hyperspectral multipoint confocal fluorescence microscope that was developed at the Eliceiri Lab.

Human cells with the gene that codes for the protein FIT2 deleted. Green indicates an endoplasmic reticulum (ER) resident protein. The lack of FIT2 affected the structure of the ER and caused the resident protein to cluster in ER membrane aggregates, seen as large, bright-green spots. Red shows where the degradation of cell parts—called autophagy—is taking place, and the nucleus is visible in blue. This image was captured using a confocal microscope.

The brain sections are treated with fluorescent antibodies specific to a particular protein and visualized using serial electron microscopy (SEM).

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.

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.

RNA polymerase (purple) is a complex enzyme at the heart of transcription. During this process, the enzyme unwinds the DNA double helix and uses one strand (darker orange) as a template to create the single-stranded messenger RNA (green), later used by ribosomes for protein synthesis.

From the RNA polymerase II elongation complex of Saccharomyces cerevisiae (PDB entry 1I6H) as seen in PDB-101's What is a Protein? video.

A protein called kinesin (blue) is in charge of moving cargo around inside cells and helping them divide. It's powered by biological fuel called ATP (bright yellow) as it scoots along tube-like cellular tracks called microtubules (gray).