Scientists recently discovered the full molecular structure of telomerase, an enzyme important to aging and cancer. Within each cell, telomerase maintains the telomeres, or end pieces, of a chromosome, preserving genetic data and extending the life of the cell. In their study, a team from UCLA and UC Berkeley found the subunit p50, shown in red, to be a keystone in the enzyme's structure and function. Featured in the May 16, 2013 issue of Biomedical Beat.

The nucleus of a human fibroblast cell with chromatin—a substance made up of DNA and proteins—shown in various colors. Fibroblasts are one of the most common types of cells in mammalian connective tissue, and they play a key role in wound healing and tissue repair. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6888 and 6893.

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.

A team of chemists and physicists used nanotechnology and DNA's ability to self-assemble with matching RNA to create a new kind of chip for measuring gene activity. When RNA of a gene of interest binds to a DNA tile (gold squares), it creates a raised surface (white areas) that can be detected by a powerful microscope. This nanochip approach offers manufacturing and usage advantages over existing gene chips and is a key step toward detecting gene activity in a single cell. Featured in the February 20, 2008, issue of Biomedical Beat.

Mitochondria are the powerhouses of the cells, generating the energy the cells need to do their tasks and to stay alive. Researchers have studied mitochondria for some time because when these cell organelles don't work as well as they should, several diseases develop. In this photograph of cow cells taken with a microscope, the mitochondria were stained in bright yellow to visualize them in the cell. The large blue dots are the cell nuclei and the gray web is the cytoskeleton of the cells.

Stained glomeruli in the kidney. The kidney is an essential organ responsible for disposing wastes from the body and for maintaining healthy ion levels in the blood. It works like a purifier by pulling break-down products of metabolism, such as urea and ammonium, from the bloodstream for excretion in urine. The glomerulus is a structure that helps filter the waste compounds from the blood. It consists of a network of capillaries enclosed within a Bowman's capsule of a nephron, which is the structure in which ions exit or re-enter the blood in the kidney.

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Researchers crystallized complexes where a CCD-1 molecule and a molecule of the antibiotic cefotaxime were bound together. Then, they shot X-rays at the complexes to determine their structure—a process known as X-ray crystallography. This image shows the X-ray diffraction pattern of a complex.

Related to images 6764, 6766, and 6767.

Astrocytes in the cross section of a human optic nerve head

Bacillus anthracis (anthrax) cells being killed by a fluorescent trans-translation inhibitor, which disrupts bacterial protein synthesis. The inhibitor is naturally fluorescent and looks blue when it is excited by ultraviolet light in the microscope. This is a color version of Image 3481.

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Using X-ray crystallography, researchers determined the structure of a complex between CCD-1 and the antibiotic cefotaxime (purple, yellow, and blue molecule). The structure revealed that CCD-1 provides extensive hydrogen bonding (shown as dotted lines) and stabilization of the antibiotic in the active site, leading to efficient degradation of the antibiotic.

Related to images 6764, 6765, and 6766.

A light microscope image of cells 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, two cells have formed after a round of mitosis.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, and 1021.

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.

Ribonucleic acid (RNA) has a sugar-phosphate backbone and the bases adenine (A), cytosine (C), guanine (G), and uracil (U). Featured in The New Genetics.

See image 2554 for an unlabeled version of this illustration.

Adult Drosophila abdominal fat tissue showing cell nuclei labelled in magenta. The upper panel is from well-fed flies, and the lower panel is from flies that have been deprived of food for 4 hours. Starvation results in the accumulation of a key adipokine—a fat hormone (blue-green dots).

Related to images 6982, 6983, and 6985.

The intense X-rays produced by synchrotrons such as the Advanced Photon Source are ideally suited for protein structure determination. Using synchrotron X-rays and advanced computers scientists can determine protein structures at a pace unheard of decades ago.

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.

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. Regions without nuclei formed smaller compartments. 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: 6587, 6589, and 6590.

Image showing that the edge zone (top of image) of the quail embryo shows no proliferating cells (cyan), unlike the interior zone (bottom of image). Non-proliferating cell nuclei are labeled green. This image was obtained as part of a study to understand cell migration in embryos. More specifically, cell proliferation at the edge of the embryo was studied by examining the cellular uptake of a chemical compound called BrDU, which incorporates into the DNA during the S-phase of the cell cycle. Here, the cells that are positive for BrDU uptake are labeled in cyan, while other non-proliferating cell nuclei are labeled green. Notice that the vast majority of BrDU+ cells are located far away from the edge, indicating that edge cells are mostly non-proliferating. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected this image. Related to image 2807 and video 2809.

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 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.

Related to images 1010, 1011, 1012, 1013, 1015, 1016, 1017, 1018, 1019, and 1021.

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 and causes serious disease.

In this image, 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 video 5752.

The worm Caenorhabditis elegans is a popular laboratory animal because its small size and fairly simple body make it easy to study. Scientists use this small worm to answer many research questions in developmental biology, neurobiology, and genetics. This image, which was taken with transmission electron microscopy (TEM), shows a cross-section through C. elegans, revealing various internal structures.

The image is from a figure in an article published in the journal eLife. There is an annotated version of this graphic at 5760.

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.

Vibrio fischeri cells (~ 2 mm), labeled with green fluorescent protein (GFP), passing through a very narrow bottleneck in the tissues (red) of the Hawaiian bobtail squid, Euprymna scolopes, on the way to the crypts where the symbiont population resides. This image was taken using a confocal fluorescence microscope.

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.

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.

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

This is a fibroblast, a connective tissue cell that plays an important role in wound healing. Normal fibroblasts have smooth edges. In contrast, this spiky cell is missing a protein that is necessary for proper construction of the cell's skeleton. Its jagged shape makes it impossible for the cell to move normally. In addition to compromising wound healing, abnormal cell movement can lead to birth defects, faulty immune function, and other health problems.

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

Dengue virus is a mosquito-borne illness that infects millions of people in the tropics and subtropics each year. Like many viruses, dengue is enclosed by a protective membrane. The proteins that span this membrane play an important role in the life cycle of the virus. Scientists used cryo-EM to determine the structure of a dengue virus at a 3.5-angstrom resolution to reveal how the membrane proteins undergo major structural changes as the virus matures and infects a host. For more on cryo-EM see the blog post Cryo-Electron Microscopy Reveals Molecules in Ever Greater Detail. You can watch a rotating view of the dengue virus surface structure in video 3748.

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

Related to image 7010 and video 7012.

Elastin is a fibrous protein in the extracellular matrix (ECM). It is abundant in artery walls like the one shown here. As its name indicates, elastin confers elasticity. Elastin fibers are at least five times stretchier than rubber bands of the same size. Tissues that expand, such as blood vessels and lungs, need to be both strong and elastic, so they contain both collagen (another ECM protein) and elastin. In this photo, the elastin-rich ECM is colored grayish brown and is most visible at the bottom of the photo. The curved red structures near the top of the image are red blood cells.

The beating of cilia on the outside of the Hawaiian bobtail squid’s light organ concentrates Vibrio fischeri cells (green) present in the seawater into aggregates near the pore-containing tissue (red). From there, the bacterial cells (~2 mm) swim to the pores and migrate through a bottleneck into the interior crypts where a population of symbionts grow and remain for the life of the host. This image was taken using confocal fluorescence microscopy.

Related to images 7016, 7017, 7018, and 7020.

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

Developing fruit fly spermatids require caspase activity (green) for the elimination of unwanted organelles and cytoplasm via apoptosis.

The largest human cell (by volume) is the egg. Human eggs are 150 micrometers in diameter and you can just barely see one with a naked eye. In comparison, consider the eggs of chickens...or ostriches!

This image shows the structure of a synapse, or junction between two nerve cells in three dimensions. From the brain of a mouse.

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.

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.

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

Ribosomes are complex machines made up of more than 50 proteins and three or four strands of genetic material called ribosomal RNA (rRNA). The busy cellular machines make proteins, which are critical to almost every structure and function in the cell. To do so, they read protein-building instructions, which come as strands of messenger RNA. Ribosomes are found in all forms of cellular life—people, plants, animals, even bacteria. This illustration of a bacterial ribosome was produced using detailed information about the position of every atom in the complex. Several antibiotic medicines work by disrupting bacterial ribosomes but leaving human ribosomes alone. Scientists are carefully comparing human and bacterial ribosomes to spot differences between the two. Structures that are present only in the bacterial version could serve as targets for new antibiotic medications.

A mouse liver glows after being tagged with specially designed infrared-fluorescent protein (IFP). Since its discovery in 1962, green fluorescent protein (GFP) has become an invaluable resource in biomedical imaging. But because of its short wavelength, the light that makes GFP glow doesn't penetrate far in whole animals. So University of California, San Diego cell biologist Roger Tsien--who shared the 2008 Nobel Prize in chemistry for groundbreaking work with GFP--made infrared-fluorescent proteins (IFPs) that shine under longer-wavelength light, allowing whole-body imaging in small animals.

Fruit fly sperm cells glow bright green when they express the gene for green fluorescent protein (GFP).

Related to image 5871.

These cells get their name from the hairlike structures that extend from them into the fluid-filled tube of the inner ear. When sound reaches the ear, the hairs bend and the cells convert this movement into signals that are relayed to the brain. When we pump up the music in our cars or join tens of thousands of cheering fans at a football stadium, the noise can make the hairs bend so far that they actually break, resulting in long-term hearing loss.

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

A model of thymidylate synthase complementing protein from Thermotoga maritime.

Body organs such as the liver and kidneys process chemicals and toxins. These "target" organs are susceptible to damage caused by these substances. See image 2496 for an unlabeled version of this illustration.

The arrangement of identical molecular components can make a dramatic difference. For example, carbon atoms can be arranged into dull graphite (left) or sparkly diamonds (right). See image 2507 for an illustration with examples.

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.

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.

This crystal structure shows a conserved hypothetical protein from Mycobacterium tuberculosis. Only 12 other proteins share its sequence homology, and none has a known function. This structure indicates the protein may play a role in metabolic pathways. Featured as one of the August 2007 Protein Structure Initiative Structures of the Month.