Ribosomes manufacture proteins based on mRNA instructions. Each ribosome reads mRNA, recruits tRNA molecules to fetch amino acids, and assembles the amino acids in the proper order.

About half of all human proteins include chains of sugar molecules that are critical for the proteins to function properly. Appears in the NIGMS booklet Inside the Cell.

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.

The receptor is shown bound to an antagonist, JDTic.

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.

Like tractor-trailers on a highway, small sacs called vesicles transport substances within cells. This image tracks the motion of vesicles in a living cell. The short red and yellow marks offer information on vesicle movement. The lines spanning the image show overall traffic trends. Typically, the sacs flow from the lower right (blue) to the upper left (red) corner of the picture. Such maps help researchers follow different kinds of cellular processes as they unfold.

A scanning electron microscope image of an activated mast cell. This image illustrates the interesting topography of the cell membrane, which is populated with receptors. The distribution of receptors may affect cell signaling. This image relates to a July 27, 2009 article in Computing Life.

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, 1050, 1051 and 1052.

CCD-1 is an enzyme produced by the bacterium Clostridioides difficile that helps it resist antibiotics. Here, researchers crystallized bound pairs of CCD-1 molecules and molecules of the antibiotic cefotaxime. This enabled their structure to be studied using X-ray crystallography.

Related to images 6765, 6766, and 6767.

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

Cdc42, a member of the Rho family of small guanosine triphosphatase (GTPase) proteins, regulates multiple cell functions, including motility, proliferation, apoptosis, and cell morphology. In order to fulfill these diverse roles, the timing and location of Cdc42 activation must be tightly controlled. Klaus Hahn and his research group use special dyes designed to report protein conformational changes and interactions, here in living neutrophil cells. Warmer colors in this image indicate higher levels of activation. Cdc42 looks to be activated at cell protrusions.

Related to images 2451, 2452, and 2453.

The marine bacterium Vibrio harveyi glows when near its kind. This luminescence, which results from biochemical reactions, is part of the chemical communication used by the organisms to assess their own population size and distinguish themselves from other types of bacteria. But V. harveyi only light up when part of a large group. This communication, called quorum sensing, speaks for itself here on a lab dish, where more densely packed areas of the bacteria show up blue. Other types of bacteria use quorum sensing to release toxins, trigger disease, and evade the immune system.

The receptor is shown bound to an antagonist, ML056.

This fused chromosome has two functional centromeres, shown as two sets of red and green dots. Centromeres are DNA/protein complexes that are key to splitting the chromosomes evenly during cell division. When dicentric chromosomes like this one are formed in a person, fertility problems or other difficulties may arise. Normal chromosomes carrying a single centromere (one set of red and green dots) are also visible in this image.

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

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.

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.

Scientists revealed a detailed image of the genetic defect that causes myotonic dystrophy type 2 and used that information to design drug candidates to counteract the disease.

A large number of proteins interact with the hormone insulin as it is produced in and secreted from the beta cells of the pancreas. In this image, the interactions of TMEM24 protein (green) and insulin (red) in pancreatic beta cells are shown in yellow. More information about the research behind this image can be found in a Biomedical Beat Blog posting from November 2013.

Insect brains, like the honeybee brain shown here, are very different in shape from human brains. Despite that, bee and human brains have a lot in common, including many of the genes and neurochemicals they rely on in order to function. The bright-green spots in this image indicate the presence of tyrosine hydroxylase, an enzyme that allows the brain to produce dopamine. Dopamine is involved in many important functions, such as the ability to experience pleasure. This image was captured using confocal microscopy.

These six-month-old axolotls, a kind of salamander, glow green and blue under ultraviolet light. That's because they were genetically modified to make harmless green fluorescent protein, or GFP. Like X-ray vision, GFP lets you see inside the axolotls as they hang out in their aquarium. GFP not only can reveal internal structures in living organisms, but it also can light up specific cells and even proteins within a cell. That allows scientists to identify and track things like cancer cells.

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

This network map shows molecular interactions (yellow) associated with a congenital condition that causes heart arrhythmias and the targets for drugs that alter these interactions (red and blue).

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

During DNA replication, each strand of the original molecule acts as a template for the synthesis of a new, complementary DNA strand. See image 2544 for a labeled version of this illustration.

Just as our bodies rely on bones for structural support, our cells rely on a cellular skeleton. In addition to helping cells keep their shape, this cytoskeleton transports material within cells and coordinates cell division. One component of the cytoskeleton is a protein called tubulin, shown here as thin strands.

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

Shortly after a pregnant woman gives birth, her breasts start to secrete milk. This process is triggered by hormonal and genetic cues, including the protein Elf5. Scientists discovered that Elf5 also has another job--it staves off cancer. Early in the development of breast cancer, human breast cells often lose Elf5 proteins. Cells without Elf5 change shape and spread readily--properties associated with metastasis. This image shows cells in the mouse mammary gland that are lacking Elf5, leading to the overproduction of other proteins (red) that increase the likelihood of metastasis.

Mitosis creates cells, and apoptosis kills them. The processes often work together to keep us healthy.

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.

This is the first structure of a protein derived from the metagenomic sequences collected during the Sorcerer II Global Ocean Sampling project. The crystal structure shows a barrel protein with a ferredoxin-like fold and a long chain fatty acid in a deep cleft (shaded red). Featured as one of the August 2007 Protein Structure Initiative Structures of the Month.

A segment of siRNA, shown in red, guides a "slicer" protein called Argonaute (multi-colored twists and corkscrews) to the target RNA molecules.

A cross section of the measles virus in which six proteins (enlarged on the outside of the virus) work together to infect cells. The measles virus is extremely infectious; 9 out of 10 people exposed will contract the disease. Fortunately, an effective vaccine protects against infection. Portions of the proteins that have not been determined are shown with dots.

Learn more about the six proteins on PDB 101’s Molecule of the Month: Measles Virus Proteins. Structures are available for the ordered regions of nucleoprotein and phosphoprotein (PDB entries 5E4V, 3ZDO, 1T6O), but the remaining regions are thought to form a flexible, random tangle. For a larger look at the measles virus, see 6995.

The new highly efficient parallelized DelPhi software was used to calculate the potential map distribution of an entire virus, the adeno-associated virus, which is made up of more than 484,000 atoms. Despite the relatively large dimension of this biological system, resulting in 815x815x815 mesh points, the parallelized DelPhi, utilizing 100 CPUs, completed the calculations within less than three minutes. Related to image 3374.

Two cells over a 2-hour period. The one on the bottom left goes through programmed cell death, also known as apoptosis. The one on the top right goes through cell division, also called mitosis. This video was captured using a confocal microscope.

After multiplying inside a host cell, the stringlike Ebola virus is emerging to infect more cells. Ebola is a rare, often fatal disease that occurs primarily in tropical regions of sub-Saharan Africa. The virus is believed to spread to humans through contact with wild animals, especially fruit bats. It can be transmitted between one person and another through bodily fluids.

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

The new highly efficient parallelized DelPhi software was used to calculate the potential map distribution of an entire virus, the adeno-associated virus, which is made up of more than 484,000 atoms. Despite the relatively large dimension of this biological system, resulting in 815x815x815 mesh points, the parallelized DelPhi, utilizing 100 CPUs, completed the calculations within less than three minutes. Related to image 3375.

A crane fly spermatocyte during metaphase of meiosis-I, a step in the production of sperm. A meiotic spindle pulls apart three pairs of autosomal chromosomes, along with a sex chromosome on the right. Tubular mitochondria surround the spindle and chromosomes. This video was captured with quantitative orientation-independent differential interference contrast and is a time lapse showing a 1-second image taken every 30 seconds over the course of 30 minutes.

More information about the research that produced this video can be found in the J. Biomed Opt. paper “Orientation-Independent Differential Interference Contrast (DIC) Microscopy and Its Combination with Orientation-Independent Polarization System” by Shribak et. al.

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.

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 the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon green), ribosomes (small pale-yellow circles), and lysosomes (large yellowish-green circles). Black line (bottom right of the left image) represents 200 nm. This image is a still from video 6609.

Two fruit fly (Drosophila melanogaster) egg cells, one on each side of the central black line. The colorful swirls show the circular movement of cytoplasm—called ooplasmic streaming—that occurs in late egg cell development in wild-type (right) and mutant (left) oocytes. This image was captured using confocal microscopy.

More information on the research that produced this image can be found in the Journal of Cell Biology paper “Ooplasmic flow cooperates with transport and anchorage in Drosophila oocyte posterior determination” by Lu et al.

The incredible complexity of a mammalian eye (in this case from a mouse) is captured here. Each color represents a different type of cell. In total, there are nearly 70 different cell types, including the retina's many rings and the peach-colored muscle cells clustered on the left.

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

HIV is a retrovirus, a type of virus that carries its genetic material not as DNA but as RNA. Long before anyone had heard of HIV, researchers in labs all over the world studied retroviruses, tracing out their life cycle and identifying the key proteins the viruses use to infect cells. When HIV was identified as a retrovirus, these studies gave AIDS researchers an immediate jump-start. The previously identified viral proteins became initial drug targets. See images 2514 and 2515 for labeled versions of this illustration. Featured in The Structures of Life.

Structure of the bacterial antitoxin protein GhoS. GhoS inhibits the production of a bacterial toxin, GhoT, which can contribute to antibiotic resistance. GhoS is the first known bacterial antitoxin that works by cleaving the messenger RNA that carries the instructions for making the toxin. More information can be found in the paper: Wang X, Lord DM, Cheng HY, Osbourne DO, Hong SH, Sanchez-Torres V, Quiroga C, Zheng K, Herrmann T, Peti W, Benedik MJ, Page R, Wood TK. A new type V toxin-antitoxin system where mRNA for toxin GhoT is cleaved by antitoxin GhoS. Nat Chem Biol. 2012 Oct;8(10):855-61. Related to 3427.

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.

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 3498 and 3500.

DNA consists of two long, twisted chains made up of nucleotides. Each nucleotide contains one base, one phosphate molecule, and the sugar molecule deoxyribose. The bases in DNA nucleotides are adenine, thymine, cytosine, and guanine. See image 2541 for an unlabeled version of this illustration. Featured in The New Genetics.

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 1052.

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.

Hippocampal neuron in culture. Dendrites are green, dendritic spines are red and DNA in cell's nucleus is blue. Image is featured on Biomedical Beat blog post Anesthesia and Brain Cells: A Temporary Disruption?

Some nerve cells (neurons) in the brain keep track of the daily cycle. This time-keeping mechanism, called the circadian clock, is found in all animals including us. The circadian clock controls our daily activities such as sleep and wakefulness. Researchers are interested in finding the neuron circuits involved in this time keeping and how the information about daily time in the brain is relayed to the rest of the body. In this image of a brain of the fruit fly Drosophila the time-of-day information flowing through the brain has been visualized by staining the neurons involved: clock neurons (shown in blue) function as "pacemakers" by communicating with neurons that produce a short protein called leucokinin (LK) (red), which, in turn, relays the time signal to other neurons, called LK-R neurons (green). This signaling cascade set in motion by the pacemaker neurons helps synchronize the fly's daily activity with the 24-hour cycle. To learn more about what scientists have found out about circadian pacemaker neurons in the fruit fly see this news release by New York University. This work was featured in the Biomedical Beat blog post Cool Image: A Circadian Circuit.