To splice a human gene into a plasmid, scientists take the plasmid out of an E. coli bacterium, cut the plasmid with a restriction enzyme, and splice in human DNA. The resulting hybrid plasmid can be inserted into another E. coli bacterium, where it multiplies along with the bacterium. There, it can produce large quantities of human protein. See image 2565 for a labeled version of this illustration. Featured in The New Genetics.

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.

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.

Real-time footage of Caenorhabditis elegans, a tiny roundworm, trapped by a carnivorous fungus, Arthrobotrys dactyloides. This fungus makes ring traps in response to the presence of C. elegans. When a worm enters a ring, the trap rapidly constricts so that the worm cannot move away, and the fungus then consumes the worm. The size of the imaged area is 0.7mm x 0.9mm.

This video was obtained with a polychromatic polarizing microscope (PPM) in white light that shows the polychromatic birefringent image with hue corresponding to the slow axis orientation. More information about PPM can be found in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak.

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

An atomic force microscopy image shows DNA folded into an intricate, computer-designed structure. Image is featured on Biomedical Beat blog post Cool Image: DNA Origami. See also related image 3689 .

RNA incorporated into the CRISPR surveillance complex is positioned to scan across foreign DNA. Cryo-EM density from a 3Å reconstruction is shown as a yellow mesh.

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.

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 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.

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.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-out version 5769 of this illustration.

In the worm C. elegans, double-stranded RNA made in neurons can silence matching genes in a variety of cell types through the transport of RNA between cells. The head region of three worms that were genetically modified to express a fluorescent protein were imaged and the images were color-coded based on depth. The worm on the left lacks neuronal double-stranded RNA and thus every cell is fluorescent. In the middle worm, the expression of the fluorescent protein is silenced by neuronal double-stranded RNA and thus most cells are not fluorescent. The worm on the right lacks an enzyme that amplifies RNA for silencing. Surprisingly, the identities of the cells that depend on this enzyme for gene silencing are unpredictable. As a result, worms of identical genotype are nevertheless random mosaics for how the function of gene silencing is carried out. For more, see journal article and press release. Related to image 6534.

A 20-µm thick section of mouse midbrain. The nerve cells are transparent and weren’t stained. Instead, the color is generated by interaction of white polarized light with the molecules in the cells and indicates their orientation.

The image was obtained with a polychromatic polarizing microscope that shows the polychromatic birefringent image with hue corresponding to the slow axis orientation. More information about the microscopy that produced this image can be found in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak.

Video of high-resolution confocal images depicting vimentin immunofluorescence (green) and nuclei (blue) at the edge of a quail embryo yolk. These images were obtained as part of a study to understand cell migration in embryos. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected these images. Related to images 2807 and 2808.

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.

A combination of protein structures determined experimentally and computationally shows us the complete metabolic network of a heat-loving bacterium.

Scanning electron micrograph of an apoptotic HeLa cell. Zeiss Merlin HR-SEM. See related images 3518, 3520, 3521, 3522.

To splice a human gene (in this case, the one for insulin) into a plasmid, scientists take the plasmid out of an E. coli bacterium, cut the plasmid with a restriction enzyme, and splice in insulin-making human DNA. The resulting hybrid plasmid can be inserted into another E. coli bacterium, where it multiplies along with the bacterium. There, it can produce large quantities of insulin. See image 2564 for an unlabeled version of this illustration. Featured in The New Genetics.

Meiosis is the process whereby a cell reduces its chromosomes from diploid to haploid in creating eggs or sperm. See image 2545 for an unlabeled version of this illustration. See image 2544 for an unlabeled version of this illustration. Featured in The New Genetics.

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 (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 is a computer-generated model of the approximately 4.2 million atoms of the HIV capsid, the shell that contains the virus' genetic material. Scientists determined the exact structure of the capsid and the proteins that it's made of using a variety of imaging techniques and analyses. They then entered these data into a supercomputer that produced the atomic-level image of the capsid. This structural information could be used for developing drugs that target the capsid, possibly leading to more effective therapies. Related to image 6601.

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.

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.

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.

The molecules that glow blue in these cultured cells prevent the expression of the mutant proteins that cause Huntington's disease. Biochemist David Corey and others at UT Southwestern Medical Center designed the molecules to specifically target the genetic repeats that code for harmful proteins in people with Huntington's disese. People with Huntington's disease and similar neurodegenerative disorders often have extra copies of a gene segment. Moving from cell cultures to animals will help researchers further explore the potential of their specially crafted molecule to treat brain disorders. In addition to NIGMS, NIH's National Institute of Neurological Disorders and Stroke and National Institute of Biomedical Imaging and Bioengineering also funded this work.

The enzyme CCP is found in the mitochondria of baker’s yeast. Scientists study the chemical reactions that CCP triggers, which involve a water molecule, iron, and oxygen. This structure was determined using an X-ray free electron laser.

Cell mopping up.

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.

Ionic and covalent bonds hold molecules, like sodium chloride and chlorine gas, together. Hydrogen bonds among molecules, notably involving water, also play an important role in biology. See image 2519 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

Collecting and transporting cellular waste and sorting it into recylable and nonrecylable pieces is a complex business in the cell. One key player in that process is the endosome, which helps collect, sort and transport worn-out or leftover proteins with the help of a protein assembly called the endosomal sorting complexes for transport (or ESCRT for short). These complexes help package proteins marked for breakdown into intralumenal vesicles, which, in turn, are enclosed in multivesicular bodies for transport to the places where the proteins are recycled or dumped. In this image, two multivesicular bodies (with yellow membranes) contain tiny intralumenal vesicles (with a diameter of only 25 nanometers; shown in red) adjacent to the cell's vacuole (in orange).

Scientists working with baker's yeast (Saccharomyces cerevisiae) study the budding inward of the limiting membrane (green lines on top of the yellow lines) into the intralumenal vesicles. This tomogram was shot with a Tecnai F-20 high-energy electron microscope, at 29,000x magnification, with a 0.7-nm pixel, ~4-nm resolution.

To learn more about endosomes, see the Biomedical Beat blog post The Cell’s Mailroom. Related to a microscopy photograph 5768 that was used to generate this illustration and a zoomed-in version 5767 of this illustration.

A Janus particle being used to activate a T cell, a type of immune cell. A Janus particle is a specialized microparticle with different physical properties on its surface, and this one is coated with nickel on one hemisphere and anti-CD3 antibodies (light blue) on the other. The nickel enables the Janus particle to be moved using a magnet, and the antibodies bind to the T cell and activate it. The T cell in this video was loaded with calcium-sensitive dye to visualize calcium influx, which indicates activation. The intensity of calcium influx was color coded so that warmer color indicates higher intensity. Being able to control Janus particles with simple magnets is a step toward controlling individual cells’ activities without complex magnetic devices.

More details can be found in the Angewandte Chemie paper “Remote control of T cell activation using magnetic Janus particles” by Lee et al. This video was captured using epi-fluorescence microscopy.

Related to video 6801.

Astrocytes in the cross section of a human optic nerve head

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.

Closeup of C. elegans, tiny roundworms, with a ribosomal protein glowing red and muscle fibers glowing green. Researchers used these worms to study a molecular pathway that affects aging. The ribosomal protein is involved in protein translation and may play a role in dietary restriction-induced longevity. Image created using confocal microscopy.
View single roundworm here 6581.
View group of roundworms here 6582.

A computer model shows how the endoplasmic reticulum is close to and almost wraps around mitochondria in the cell. The endoplasmic reticulum is lime green and the mitochondria are yellow. This image relates to a July 27, 2009 article in Computing Life.

3D reconstructions of two stages in the assembly of the bacterial ribosome created from time-resolved cryo-electron microscopy images. Ribosomes translate genetic instructions into proteins.

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 2506 for an illustration without examples.

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 2551 for a labeled version of this illustration. Featured in The New Genetics.

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible. 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: 6588, 6589, and 6590.

Hippocampal neuron from rodent brain with dendrites shown in blue. The hundreds of tiny magenta, green and white dots are the dendritic spines of excitatory synapses.

CellPack image of the H1N1 influenza virus, with hemagglutinin and neuraminidase glycoproteins in green and red, respectively, on the outer envelope (white); matrix protein in gray, and ribonucleoprotein particles inside the virus in red and green. Related to image 6356.

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.

Researchers used cryo-electron tomography (cryo-ET) to capture images of a rat pancreas cell that were then compiled and color-coded to produce a 3D reconstruction. Visible features include the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon-green rods), a mitochondria membrane (pink), ribosomes (small pale-yellow circles), endoplasmic reticulum (aqua), and lysosomes (large yellowish-green circles). See 6606 for a still image from the video.

Acetylsalicylate (bottom) is the aspirin of today. Adding a chemical tag called an acetyl group (shaded box, bottom) to a molecule derived from willow bark (salicylate, top) makes the molecule less acidic (and easier on the lining of the digestive tract), but still effective at relieving pain. See image 2529 for an unlabeled version of this illustration. Featured in Medicines By Design.

Here, a human HeLa cell (a type of immortal cell line used in laboratory experiments) is undergoing cell division. They come from cervical cancer cells that were obtained in 1951 from Henrietta Lacks, a patient at the Johns Hopkins Hospital. The final stage of division, called cytokinesis, occurs after the genomes—shown in yellow—have split into two new daughter cells. The myosin II is a motor protein shown in blue, and the actin filaments, which are types of protein that support cell structure, are shown in red.

Hippocampal cells in culture with a neuron in green, showing hundreds of the small protrusions known as dendritic spines. The dendrites of other neurons are labeled in blue, and adjacent glial cells are shown in red.

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.

The cerebellum is the brain's locomotion control center. Found at the base of your brain, the cerebellum is a single layer of tissue with deep folds like an accordion. People with damage to this region of the brain often have difficulty with balance, coordination and fine motor skills.

This image of a mouse cerebellum is part of a collection of such images in different colors and at different levels of magnification from the National Center for Microscopy and Imaging Research (NCMIR). Related to image 5800.