A computer model of the cell membrane, where the plasma membrane is red, endoplasmic reticulum is yellow, and mitochondria are blue. This image relates to a July 27, 2009 article in Computing Life.

Active site of E. coli response regulator PhoB.

Model of a protein, antigen 85B, that is the most abundant protein exported by Mycobacterium tuberculosis, which causes most cases of tuberculosis. Antigen 85B is involved in building the bacterial cell wall and is an attractive drug target. Based on its structure, scientists have suggested a new class of antituberculous drugs.

Network diagram showing a map of protein-protein interactions in a yeast (Saccharomyces cerevisiae) cell. This cluster includes 78 percent of the proteins in the yeast proteome. The color of a node represents the phenotypic effect of removing the corresponding protein (red, lethal; green, nonlethal; orange, slow growth; yellow, unknown).

These microscopic roundworms, called Caenorhabditis elegans, lack eyes and the opsin proteins used by visual systems to detect colors. However, researchers found that the worms can still sense the color of light in a way that enables them to avoid pigmented toxins made by bacteria. This image was captured using a stereo microscope.

Although they are tiny, microbes that are growing in confined spaces can generate a lot of pressure. In this video, yeast cells grow in a small chamber called a microfluidic bioreactor. As the cells multiply, they begin to bump into and squeeze each other, resulting in periodic bursts of cells moving into different parts of the chamber. The continually growing cells also generate a lot of pressure--the researchers conducting these experiments found that the pressure generated by the cells can be almost five times higher than that in a car tire--about 150 psi, or 10 times the atmospheric pressure. Occasionally, this pressure even caused the small reactor to burst. By tracking the growth of the yeast or other cells and measuring the mechanical forces generated, scientists can simulate microbial growth in various places such as water pumps, sewage lines or catheters to learn how damage to these devices can be prevented. To learn more how researchers used small bioreactors to gauge the pressure generated by growing microbes, see this press release from UC Berkeley.

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 and are separating to form the cores of two new cells.

Related to images 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

A cross section of the measles virus in which six proteins 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.

For a zoomed-in look at the six important proteins, see Measles Virus Proteins.

These mitochondria (brown) are from the heart muscle cell of a rat. Mitochondria have an inner membrane that folds in many places (and that appears here as striations). This folding vastly increases the surface area for energy production. Nearly all our cells have mitochondria. Related to image 3661.

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).

Meiosis is the process whereby a cell reduces its chromosomes from diploid to haploid in creating eggs or sperm. See image 2546 for a labeled version of this illustration. Featured in The New Genetics.

These mitochondria (red) are from the heart muscle cell of a rat. Mitochondria have an inner membrane that folds in many places (and that appears here as striations). This folding vastly increases the surface area for energy production. Nearly all our cells have mitochondria. Related to image 3664.

Just 22 hours after fertilization, this zebrafish embryo is already taking shape. By 36 hours, all of the major organs will have started to form. The zebrafish's rapid growth and see-through embryo make it ideal for scientists studying how organs develop.

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

Proteins are made of amino acids hooked end-to-end like beads on a necklace. To become active, proteins must twist and fold into their final, or "native," conformation. A protein's final shape enables it to accomplish its function. Featured in The Structures of Life.

Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3744 and 3745.

This fiery image doesn’t come from inside a bubbling volcano. Instead, it shows animal cells caught in the act of making bubbles, or blebbing. Some cells regularly pinch off parts of their membranes to produce bubbles filled with a mix of proteins and fats. The bubbles (red) are called plasma-derived membrane vesicles, or PMVs, and can travel to other parts of the body where they may aid in cell-cell communication. The University of Texas, Austin, researchers responsible for this photo are exploring ways to use PMVs to deliver medicines to precise locations in the body.

This image, entered in the Biophysical Society’s 2017 Art of Science Image contest, used two-channel spinning disk confocal fluorescence microscopy. It was also featured in the NIH Director’s Blog in May 2017.

This image is featured on the poster for Dr. Rommie Amaro's 2017 Stetten Lecture. It depicts a detailed physical model of an influenza virus, incorporating information from several structural data sources. The small molecules around the virus are sialic acid molecules. The virus binds to and cleaves sialic acid as it enters and exits host cells. Researchers are building these highly detailed molecular scale models of different biomedical systems and then “bringing them to life” with physics-based methods, either molecular or Brownian dynamics simulations, to understand the structural dynamics of the systems and their complex interactions with drug or substrate molecules.

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

This animation shows atoms of the HIV capsid, the shell that encloses the virus's genetic material. Scientists determined the exact structure of the capsid using a variety of imaging techniques and analyses. They then entered this data into a supercomputer to produce this image. Related to image 3477.

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 and are starting to line up.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1017, 1018, 1019, and 1021.

A color-coded, 3D model of a rat pancreatic β cell. This type of cell produces insulin, a hormone that helps regulate blood sugar. Visible are mitochondria (pink), insulin vesicles (yellow), the nucleus (dark blue), and the plasma membrane (teal). This model was created based on soft X-ray tomography (SXT) images.

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.

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 1051.

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.
For imagery of both the lateral and overhead view go to 3556.
For imagery of the lateral view go to 3558.
For more information about the illumated area go to 3559.

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), Arp2 (green), and DAPI to visualize the nucleus (blue). Arp2, a subunit of the Arp2/3 complex, is absent in the filopodi-like structures based leading edge of ARPC3-/- fibroblasts cells. Related to images 3328, 3330, 3331, 3332, and 3333.

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.

Living primary mouse embryonic fibroblasts. Mitochondria (green) stained with the mitochondrial membrane potential indicator, rhodamine 123. Nuclei (blue) are stained with DAPI. Caption from a November 26, 2012 news release from U Penn (Penn Medicine).

DNA doesn't leave a fossil record in stone, the way bones do. Instead, the DNA code itself holds the best evidence for organisms' genetic history. Some of the most telling evidence about genetic history comes from retroviruses, the remnants of ancient viral infections.

Trypanosoma brucei is a single-cell parasite that causes sleeping sickness in humans. Scientists have been studying trypanosomes for some time because of their negative effects on human and also animal health, especially in sub-Saharan Africa. Moreover, because these organisms evolved on a separate path from those of animals and plants more than a billion years ago, researchers study trypanosomes to find out what traits they may harbor that are common to or different from those of other eukaryotes (i.e., those organisms having a nucleus and mitochondria). This image shows the T. brucei cell membrane in red, the DNA in the nucleus and kinetoplast (a structure unique to protozoans, including trypanosomes, which contains mitochondrial DNA) in blue and nuclear pore complexes (which allow molecules to pass into or out of the nucleus) in green. Scientists have found that the trypanosome nuclear pore complex has a unique mechanism by which it attaches to the nuclear envelope. In addition, the trypanosome nuclear pore complex differs from those of other eukaryotes because its components have a near-complete symmetry, and it lacks almost all of the proteins that in other eukaryotes studied so far are required to assemble the pore.

Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3744 and 3746

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. This is the fifthframe in a series of five. The CRISPR system has two components joined together: a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence) and a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA). For an explanation and overview of the CRISPR-Cas9 system, see the NIGMS Biomedical Beat blog entry, Field Focus: Precision Gene Editing with CRISPR and the iBiology video, Genome Engineering with CRISPR-Cas9: Birth of a Breakthrough Technology.

Multicellular yeast called snowflake yeast that researchers created through many generations of directed evolution from unicellular yeast. Here, the researchers visualized nuclei in orange to help them study changes in how the yeast cells divided. Cell walls are shown in blue. This image was captured using spinning disk confocal microscopy.

Related to images 6969 and 6970.

Of the three muscle fibers shown here, the one on the right and the one on the left are normal. The middle fiber is deficient a large protein called nebulin (blue). Nebulin plays a number of roles in the structure and function of muscles, and its absence is associated with certain neuromuscular disorders.

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

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.

Irina Dementieva, a biochemist, and Youngchang Kim, a biophysicist and crystallographer, work with the first robot of its type in the U.S. to automate protein purification. The robot, which is housed in a refrigerator, is an integral part of the Midwest Structural Genomics Center's plan to automate the protein crystallography process.

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

A tomographic reconstruction of the colon shows the location of large pools of HIV-1 virus particles (in blue) located in the spaces between adjacent cells. The purple objects within each sphere represent the conical cores that are one of the structural hallmarks of the HIV virus.

Hydra magnipapillata is an invertebrate animal used as a model organism to study developmental questions, for example the formation of the body axis.

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

Proteins are 3D structures made up of smaller units. DNA is transcribed to RNA, which in turn is translated into amino acids. Amino acids form a protein strand, which has sections of corkscrew-like coils, called alpha helices, and other sections that fold flat, called beta sheets. The protein then goes through complex folding to produce the 3D structure.

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 2513 and 2514 for other versions of this illustration. Featured in The Structures of Life.

In the top snapshots, the brain of a sleep-deprived fruit fly glows orange, marking high concentrations of a synaptic protein called Bruchpilot (BRP) involved in communication between neurons. The color particularly lights up brain areas associated with learning. By contrast, the bottom images from a well-rested fly show lower levels of the protein. These pictures illustrate the results of an April 2009 study showing that sleep reduces the protein's levels, suggesting that such "downscaling" resets the brain to normal levels of synaptic activity and makes it ready to learn after a restful night.

Fat tissue from the abdomen of a genetically mosaic adult fruit fly. Genetic mosaicism means that the fly has cells with different genotypes even though it formed from a single zygote. This specific mosaicism results in accumulation of a critical fly adipokine (blue-green) within the fat tissue cells that have reduced expression a key nutrient sensing gene (in left panel). The dotted line shows the cells lacking the gene that is present and functioning in the rest of the cells. Nuclei are labelled in magenta. This image was captured using a confocal microscope and shows a maximum intensity projection of many slices.

Related to images 6982, 6984, and 6985.

Various views of a zebrafish head with blood vessels shown in purple. Researchers often study zebrafish because they share many genes with humans, grow and reproduce quickly, and have see-through eggs and embryos, which make it easy to study early stages of development.

This video was captured using a light sheet microscope.

Related to image 6934.

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.

This video results from a research project to visualize which regions of the adult fruit fly (Drosophila) brain derive from each neural stem cell. First, researchers collected several thousand fruit fly larvae and fluorescently stained a random stem cell in the brain of each. The idea was to create a population of larvae in which each of the 100 or so neural stem cells was labeled at least once. When the larvae grew to adults, the researchers examined the flies’ brains using confocal microscopy. With this technique, the part of a fly’s brain that derived from a single, labeled stem cell “lights up.” The scientists photographed each brain and digitally colorized its lit-up area. By combining thousands of such photos, they created a three-dimensional, color-coded map that shows which part of the Drosophila brain comes from each of its ~100 neural stem cells. In other words, each colored region shows which neurons are the progeny or “clones” of a single stem cell. This work established a hierarchical structure as well as nomenclature for the neurons in the Drosophila brain. Further research will relate functions to structures of the brain.

Related to images 5838 and 5868.

Undifferentiated embryonic stem cells cease to exist a few days after conception. In this image, ES cells are shown to differentiate into sperm, muscle fiber, hair cells, nerve cells, and cone cells.

This time-lapse video shows the emergence of a flower-like pattern in a mixture of two bacterial species, motile Acinetobacter baylyi and non-motile Escherichia coli (green), that are grown together for 24 hours on 0.75% 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 6553 for a photo of this process at 48 hours on 1% 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.

Sketch of an egg cell.