Cell division is an incredibly coordinated process. It not only ensures that the new cells formed during this event have a full set of chromosomes, but also that they are endowed with all the cellular materials, including proteins, lipids and small functional compartments called organelles, that are required for normal cell activity. This proper apportioning of essential cell ingredients helps each cell get off to a running start.

This image shows an electron microscopy (EM) thin section taken at 10,000x magnification of a dividing yeast cell over-expressing the protein ubiquitin, which is involved in protein degradation and recycling. The picture features mother and daughter endosome accumulations (small organelles with internal vesicles), a darkly stained vacuole and a dividing nucleus in close contact with a cadre of lipid droplets (unstained spherical bodies).  Other dynamic events are also visible,  such as spindle microtubules in the nucleus and endocytic pits at the plasma membrane.

These extensive details were revealed thanks to a preservation method involving high-pressure freezing, freeze-substitution and Lowicryl HM20 embedding.

Multiple actin filaments (magenta) are organized around a dynamin helical polymer (rainbow colored) in this model derived from cryo-electron tomography. By bundling actin, dynamin increases the strength of a cell’s skeleton and plays a role in cell-cell fusion, a process involved in conception, development, and regeneration.

Staphylococcus aureus bacteria (blue) on the porous coating of a femoral hip stem used in hip replacement surgery. The relatively rough surface of an implant is a favorable environment for bacteria to attach and grow. This can lead to the development of biofilms, which can cause infections. The researchers who took this image are working to understand where biofilms are likely to develop. This knowledge could support the prevention and treatment of infections. A scanning electron microscope was used to capture this image.

More information on the research that produced this image can be found in the Antibiotics paper "Free-floating aggregate and single-cell-initiated biofilms of Staphylococcus aureus" by Gupta et al.

Related to image 6803 and video 6805.

A 360-degree view of the molecule himastatin, which was first isolated from the bacterium Streptomyces himastatinicus. Himastatin shows antibiotic activity. The researchers who created this video developed a new, more concise way to synthesize himastatin so it can be studied more easily.

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

Related to images 6848 and 6850.

The genetic code in DNA is transcribed into RNA, which is translated into proteins with specific sequences. During transcription, nucleotides in DNA are copied into RNA, where they are read three at a time to encode the amino acids in a protein. Many parts of a protein fold as the amino acids are strung together.

See image 2509 for an unlabeled version of this illustration.

Featured in The Structures of Life.

Arranging exons in different patterns, called alternative splicing, enables cells to make different proteins from a single gene. See image 2553 for a labeled version of this illustration. Featured in The New Genetics.

Pigment cells are cells that give skin its color. In fishes and amphibians, like frogs and salamanders, pigment cells are responsible for the characteristic skin patterns that help these organisms to blend into their surroundings or attract mates. The pigment cells are derived from neural crest cells, which are cells originating from the neural tube in the early embryo. This image shows pigment cells from pearl danio, a relative of the popular laboratory animal zebrafish. Investigating pigment cell formation and migration in animals helps answer important fundamental questions about the factors that control pigmentation in the skin of animals, including humans. Related to images 5754, 5755, 5757 and 5758.

Force vectors computed from actin cytoskeleton flow. This is an example of NIH-supported research on single-cell analysis. Related to 2798, 2800, 2801, 2802 and 2803.

To develop a system for studying cell motility in unnatrual conditions -- a microscope slide instead of the body -- Tom Roberts and Katsuya Shimabukuro at Florida State University disassembled and reconstituted the motility parts used by worm sperm cells.

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.

The structure of the pore-forming protein VDAC-1 from humans. This molecule mediates the flow of products needed for metabolism--in particular the export of ATP--across the outer membrane of mitochondria, the power plants for eukaryotic cells. VDAC-1 is involved in metabolism and the self-destruction of cells--two biological processes central to health.

Related to images 2494, 2495, and 2488.

Neuron from a crab showing the cell body (bottom), axon (rope-like extension), and growth cone (top right).

A nanometer-sized biosensor can detect a single deadly bacterium in tainted ground beef. How? Researchers attached nanoparticles, each packed with thousands of dye molecules, to an antibody that recognizes the microbe E. coli O157:H7. When the nanoball-antibody combo comes into contact with the E. coli bacterium, it glows. Here is the transition, a single bacterial cell glows brightly when it encounters nanoparticle-antibody biosensors, each packed with thousands of dye molecules.

Fruit fly (Drosophila melanogaster) ovaries with DNA shown in magenta and actin filaments shown in light blue. This image was captured using a confocal laser scanning microscope.

Related to image 6806.

This image of the hippocampus was taken with an ultra-widefield high-speed multiphoton laser microscope. Tissue was stained to reveal the organization of glial cells (cyan), neurofilaments (green) and DNA (yellow). The microscope Deerinck used was developed in conjunction with Roger Tsien (2008 Nobel laureate in Chemistry) and remains a powerful and unique tool today.

Luciferase-based imaging enables visualization and quantification of internal organs and transplanted cells in live adult zebrafish. This image shows how luciferase-based imaging could be used to visualize the heart for regeneration studies (left), or label all tissues for stem cell transplantation (right).
For imagery of both the lateral and overhead view go to 3556.
For imagery of the overhead view go to 3557.
For imagery of the lateral view go to 3558.

If a picture is worth a thousand words, what's a movie worth? For researchers studying cell migration, a "documentary" of fruit fly cells (bright green) traversing an egg chamber could answer longstanding questions about cell movement. Historically, researchers have been unable to watch this cell migration unfold in living ovarian tissue in real time. But by developing a culture medium that allows fly eggs to survive outside their ovarian homes, scientists can observe the nuances of cell migration as it happens. Such details may shed light on how immune cells move to a wound and why cancer cells spread to other sites. See 3594 for still image.

Learn how curiosity about the world and our cells is key to scientific discoveries. Discover more resources from NIGMS’ Pathways collaboration with Scholastic. View the video on YouTube for closed captioning.

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.

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.

At the root tips of the mustard plant Arabidopsis thaliana (red), two proteins work together to control the uptake of water and nutrients. When the cell division-promoting protein called Short-root moves from the center of the tip outward, it triggers the production of another protein (green) that confines Short-root to the nutrient-filtering endodermis. The mechanism sheds light on how genes and proteins interact in a model organism and also could inform the engineering of plants.

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.

The small intestine is where most of our nutrients from the food we eat are absorbed into the bloodstream. The walls of the intestine contain small finger-like projections called villi which increase the organ's surface area, enhancing nutrient absorption. It consists of the duodenum, which connects to the stomach, the jejenum and the ileum, which connects with the large intestine. Related to image 3390.

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."

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 3500.

A research mentor (Lori Eidson) and student (Nina Waldron, on the microscope) were 2009 members of the BRAIN (Behavioral Research Advancements In Neuroscience) program at Georgia State University in Atlanta. This program is an undergraduate summer research experience funded in part by NIGMS.

A protein called tubulin (green) accumulates in the center of a nucleus (outlined in pink) from an aging cell. Normally, this protein is kept out of the nucleus with the help of gatekeepers known as nuclear pore complexes. But NIGMS-funded researchers found that wear and tear to long-lived components of the complexes eventually lowers the gatekeepers' guard. As a result, cytoplasmic proteins like tubulin gain entry to the nucleus while proteins normally confined to the nucleus seep out. The work suggests that finding ways to stop the leakage could slow the cellular aging process and possibly lead to new therapies for age-related diseases.

Detail of a subunit of the capsid, or outer cover, of bacteriophage P22, a virus that infects the Salmonella bacteria. Cryo-electron microscopy (cryo-EM) was used to capture details of the capsid proteins, each shown here in a separate color. Thousands of cryo-EM scans capture the structure and shape of all the individual proteins in the capsid and their position relative to other proteins. A computer model combines these scans into the image shown here. Related to image 5874.

When a molecule arrives at a cell's outer membrane, the membrane creates a pouch around the molecule that protrudes inward. Directed by a protein called dynamin, the pouch then gets pinched off to form a vesicle that carries the molecule to the right place inside the cell. To better understand how dynamin performs its vital pouch-pinching role, researchers determined its structure. Based on the structure, they proposed that a dynamin "collar" at the pouch's base twists ever tighter until the vesicle pops free. Because cells absorb many drugs through vesicles, the discovery could lead to new drug delivery methods.

Superresolution microscopy work on endoplasmic reticulum (ER) in the peripheral areas of the cell showing details of the structure and arrangement in a complex web of tubes.
The ER is a continuous membrane that extends like a net from the envelope of the nucleus outward to the cell membrane. The ER plays several roles within the cell, such as in protein and lipid synthesis and transport of materials between organelles. The ER has a flexible structure to allow it to accomplish these tasks by changing shape as conditions in the cell change. Shown here an image created by super-resolution microscopy of the ER in the peripheral areas of the cell showing details of the structure and the arrangements in a complex web of tubes. Related to images 5856 and 5857.

Proteins in the neural tissues of this zebrafish embryo direct cells to line up and form the neural tube, which will become the spinal cord and brain. Studies of zebrafish embryonic development may help pinpoint the underlying cause of common neural tube defects--such as spina bifida--which occur in about 1 in 1,000 newborn children.

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.

This image shows an abnormal, tetrapolar mitosis. Chromosomes are highlighted pink. The cells shown are S3 tissue cultured cells from Xenopus laevis, African clawed frog.

The goal of the Protein Structure Initiative (PSI) is to determine the three-dimensional shapes of a wide range of proteins by solving the structures of representative members of each protein family found in nature. The collection of structures should serve as a valuable resource for biomedical research scientists.

Model of a member from the Tex protein family, which is implicated in transcriptional regulation and highly conserved in eukaryotes and prokaryotes. The structure shows significant homology to a human transcription elongation factor that may regulate multiple steps in mRNA synthesis.

Each point in these colorful patchworks represents the correlation between two sleep-associated genes in fruit flies. Vibrant reds and oranges represent high and intermediate degrees of association between the genes, respectively. Genes in these areas show similar activity patterns in different fly lines. Cool blues represent gene pairs where one partner's activity is high and the other's is low. The green areas show pairs with activities that are not correlated. These quilt-like depictions help illustrate a recent finding that genes act in teams to influence sleep patterns.

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 to cause serious disease.

In this video, 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 image 5751.

Structure of a magnesium transporter protein from an antibiotic-resistant bacterium (Enterococcus faecalis) found in the human gut. Featured as one of the June 2007 Protein Sructure Initiative Structures of the Month.

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.

Those of us who get sneezy and itchy-eyed every spring or fall may have pollen grains, like those shown here, to blame. Pollen grains are the male germ cells of plants, released to fertilize the corresponding female plant parts. When they are instead inhaled into human nasal passages, they can trigger allergies.

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

The nucleus of a degenerating human tendon cell, also known as a tenocyte. It has been color-coded based on the density of chromatin—a substance made up of DNA and proteins. Areas of low chromatin density are shown in blue, and areas of high chromatin density are shown in red. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6887 and 6888.

The nucleolus is a small but very important protein complex located in the cell's nucleus. It forms on the chromosomes at the location where the genes for the RNAs are that make up the structure of the ribosome, the indispensable cellular machine that makes proteins from messenger RNAs.

However, how the nucleolus grows and maintains its structure has puzzled scientists for some time. It turns out that even though it looks like a simple liquid blob, it's rather well-organized, consisting of three distinct layers: the fibrillar center, where the RNA polymerase is active; the dense fibrillar component, which is enriched in the protein fibrillarin; and the granular component, which contains a protein called nucleophosmin. Researchers have now discovered that this multilayer structure of the nucleolus arises from difference in how the proteins in each compartment mix with water and with each other. These differences let them readily separate from each other into the three nucleolus compartments.

This video of nucleoli in the eggs of a commonly used lab animal, the frog Xenopus laevis, shows how each of the compartments (the granular component is shown in red, the fibrillarin in yellow-green, and the fibrillar center in blue) spontaneously fuse with each other on encounter without mixing with the other compartments. For more details on this research, see this press release from Princeton. Related to video 3791, image 3792 and image 3793.

Stained cross section of a mouse tail.

A cell nucleus (blue) surrounded by lipid droplets (yellow). Exogenously expressed, S-tagged UBXD8 (green) recruits endogenous p97/VCP (red) to the surface of lipid droplets in oleate-treated HeLa cells. Nucleus stained with DAPI.

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 2542 for a labeled version of this illustration. Featured in The New Genetics.

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

The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2537 for other versions of this image. Featured in Medicines By Design.

This image captures the many layers of nerve cells in the retina. The top layer (green) is made up of cells called photoreceptors that convert light into electrical signals to relay to the brain. The two best-known types of photoreceptor cells are rod- and cone-shaped. Rods help us see under low-light conditions but can't help us distinguish colors. Cones don't function well in the dark but allow us to see vibrant colors in daylight.

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

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, condensed chromosomes are clearly visible and have separated into the opposite sides of a dividing cell.

Related to images 1010, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

During embryonic development, transcription factors (proteins that regulate gene expression) govern the differentiation of cells into separate tissues and organs. Researchers at Cincinnati Children's Hospital Medical Center used mice to study the development of certain internal organs, including the liver, pancreas, duodenum (beginning part of the small intestine), gall bladder and bile ducts. They discovered that transcription factor Sox17 guides some cells to develop into liver cells and others to become part of the pancreas or biliary system (gall bladder, bile ducts and associated structures). The separation of these two distinct cell types (liver versus pancreas/biliary system) is complete by embryonic day 8.5 in mice. The transcription factors PDX1 and Hes1 are also known to be involved in embryonic development of the pancreas and biliary system. This image shows mouse cells at embryonic day 10.5. The green areas show cells that will develop into the pancreas and/or duodenum(PDX1 is labeled green). The blue area near the bottom will become the gall bladder and the connecting tubes (common duct and cystic duct) that attach the gall bladder to the liver and pancreas (Sox17 is labeled blue). The transcription factor Hes1 is labeled red. The image was not published. A similar image (different plane of the section) was published in: Sox17 Regulates Organ Lineage Segregation of Ventral Foregut Progenitor Cells Jason R. Spence, Alex W. Lange, Suh-Chin J. Lin, Klaus H. Kaestner, Andrew M. Lowy, Injune Kim, Jeffrey A. Whitsett and James M. Wells, Developmental Cell, Volume 17, Issue 1, 62-74, 21 July 2009. doi:10.1016/j.devcel.2009.05.012