During DNA replication, each strand of the original molecule acts as a template for the synthesis of a new, complementary DNA strand. See image 2543 for an unlabeled version of this illustration. Featured in The New Genetics.

It has been said that gastrulation is the most important event in a person's life. This part of early embryonic development transforms a simple ball of cells and begins to define cell fate and the body axis. In a study published in Science magazine, NIGMS grantee Bob Goldstein and his research group studied how contractions of actomyosin filaments in C. elegans and Drosophila embryos lead to dramatic rearrangements of cell and embryonic structure. In these images, myosin (green) and plasma membrane (red) are highlighted at four timepoints in gastrulation in the roundworm C. elegans. The blue highlights in the top three frames show how cells are internalized, and the site of closure around the involuting cells is marked with an arrow in the last frame. See related image 3297.

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

Bacteria engineered to act as genetic clocks flash in synchrony. Here, a "supernova" burst in a colony of coupled genetic clocks just after reaching critical cell density. Superimposed: A diagram from the notebook of Christiaan Huygens, who first characterized synchronized oscillators in the 17th century.

Vibrio, a type (genus) of rod-shaped bacteria. Some Vibrio species cause cholera in humans.

These yeast cells were exposed to a glucose (sugar) shortage. This caused the cells to compartmentalize HMGCR (green)—an enzyme involved in making cholesterol—to a patch on the nuclear envelope next to the vacuole/lysosome (purple). This process enhanced HMGCR activity and helped the yeast adapt to the glucose shortage. Researchers hope that understanding how yeast regulate cholesterol could ultimately lead to new ways to treat high cholesterol in people. This image was captured using a fluorescence microscope.

Kupffer cells appear in the liver during the early stages of mammalian development and stay put throughout life to protect liver cells, clean up old red blood cells, and regulate iron levels. Source article Replenishing the Liver’s Immune Protections. Posted on December 12th, 2019 by Dr. Francis Collins.

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.

Model of the mandelate racemase enzyme from Bacillus subtilis, a bacterium commonly found in soil.

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, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

This sculpture made of purple and clear glass beads depicts bacteriophage Phi174, a virus that infects bacteria. It rests on a surface that portrays an adaptive landscape, a conceptual visualization. The ridges represent the gene combinations associated with the greatest fitness levels of the virus, as measured by how quickly the virus can reproduce itself. Phi174 is an important model system for studies of viral evolution because its genome can readily be sequenced as it evolves under defined laboratory conditions.

The nuclei stained green highlight human embryonic stem cells grown under controlled conditions in a laboratory. Blue represents the DNA of surrounding, supportive feeder cells. Image and caption information courtesy of the California Institute for Regenerative Medicine. See related image 3724.

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.

This image shows mouse fetal heart fibroblast cells. The muscle protein actin is stained red, and the cell nuclei are stained blue. The image was part of a study investigating stem cell-based approaches to repairing tissue damage after a heart attack. Image and caption information courtesy of the California Institute for Regenerative Medicine.

Ovarioles in female insects are tubes in which egg cells (called oocytes) form at one end and complete their development as they reach the other end of the tube. This image, taken with a confocal microscope, shows ovarioles in a very popular lab animal, the fruit fly Drosophila. The basic structure of ovarioles supports very rapid egg production, with some insects (like termites) producing several thousand eggs per day. Each insect ovary typically contains four to eight ovarioles, but this number varies widely depending on the insect species.

Scientists use insect ovarioles, for example, to study the basic processes that help various insects, including those that cause disease (like some mosquitos and biting flies), reproduce very quickly.

RNA polymerase (purple) is a complex enzyme at the heart of transcription. During this process, the enzyme unwinds the DNA double helix and uses one strand (darker orange) as a template to create the single-stranded messenger RNA (green), later used by ribosomes for protein synthesis.

From the RNA polymerase II elongation complex of Saccharomyces cerevisiae (PDB entry 1I6H) as seen in PDB-101's What is a Protein? video.

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.

Both instruments shown were developed by CellFree Sciences of Yokohama, Japan. The instrument on the left, the GeneDecoder 1000, can generate 384 proteins from their corresponding genes, or gene fragments, overnight. It is used to screen for properties such as level of protein production and degree of solubility. The instrument on the right, the Protemist Protein Synthesizer, is used to generate the larger amounts of protein needed for protein structure determinations.

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.

Two adult fruit flies (Drosophila)

Groups of Staphylococcus aureus bacteria (blue) attached to a microstructured titanium surface (green) that mimics an orthopedic implant used in joint replacement. The attachment of pre-formed groups of bacteria may lead to infections because the groups can tolerate antibiotics and evade the immune system. This image was captured using a scanning electron microscope.

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 6804 and video 6805.

Many of today's medicines come from products found in nature, such as this sponge found off the coast of Palau in the Pacific Ocean. Chemists have synthesized a compound called Palau'amine, which appears to act against cancer, bacteria and fungi. In doing so, they invented a new chemical technique that will empower the synthesis of other challenging molecules.

A red poppy.

This slide shows the technologies that the Joint Center for Structural Genomics developed for going from gene to structure and how the technologies have been integrated into a high-throughput pipeline, including all of the steps from target selection, parallel expression, protein purification, automated crystallization trials, automated crystal screening, structure determination, validation, and publication.

An axolotl—a type of salamander—that has been genetically modified so that its developing nervous system glows purple and its Schwann cell nuclei appear light blue. Schwann cells insulate and provide nutrients to peripheral nerve cells. Researchers often study axolotls for their extensive regenerative abilities. They can regrow tails, limbs, spinal cords, brains, and more. The researcher who took this image focuses on the role of the peripheral nervous system during limb regeneration.

This image was captured using a stereo microscope.

Related to images 6927 and 6928.

Microscopy image of tongue. One in a series of two, see image 5811

What looks a little like distant planets with some mysterious surface features are actually assemblies of proteins normally found in the cell's nucleolus, 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 differences in how the proteins in each compartment mix with water and with each other. These differences let the proteins readily separate from each other into the three nucleolus compartments.

This photo of nucleolus proteins in the eggs of a commonly used lab animal, the frog Xenopus laevis, shows each of the nucleolus compartments (the granular component is shown in red, the fibrillarin in yellow-green, and the fibrillar center in blue). The researchers have found that these compartments 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 3789, video 3791 and image 3793.

This wreath represents the molecular structure of a protein, Cas4, which is part of a system, known as CRISPR, that bacteria use to protect themselves against viral invaders. The green ribbons show the protein's structure, and the red balls show the location of iron and sulfur molecules important for the protein's function. Scientists harnessed Cas9, a different protein in the bacterial CRISPR system, to create a gene-editing tool known as CRISPR-Cas9. Using this tool, researchers are able to study a range of cellular processes and human diseases more easily, cheaply and precisely. In December, 2015, Science magazine recognized the CRISPR-Cas9 gene-editing tool as the "breakthrough of the year." Read more about Cas4 in the December 2015 Biomedical Beat post A Holiday-Themed Image Collection.

The two large, central, round shapes are ovaries from a typical fruit fly (Drosophila melanogaster). The small butterfly-like structures surrounding them are fruit fly ovaries where researchers suppressed the expression of a gene that controls microtubule polymerization and is necessary for normal development. This image was captured using a confocal laser scanning microscope.

Related to image 6807.

A protein called kinesin (blue) is in charge of moving cargo around inside cells and helping them divide. It's powered by biological fuel called ATP (bright yellow) as it scoots along tube-like cellular tracks called microtubules (gray).

Xenopus laevis, the African clawed frog, has long been used as a model organism for studying embryonic development. In this image, RNA encoding the transcription factor Sox 7 (dark blue) is shown to predominate at the vegetal pole, the yolk-rich portion, of a Xenopus laevis frog egg. Sox 7 protein is important to the regulation of embryonic development.

Cells progress through a cycle that consists of phases for growth (G1, S, and G2) and division (M). Cells become quiescent when they exit this cycle (G0). See image 2498 for an unlabeled version of this illustration.

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.

These neurons were derived from human embryonic stem cells. The neural cell bodies with axonal projections are visible in red, and the nuclei in blue. Some of the neurons have become dopaminergic neurons (yellow), the type that degenerate in people with Parkinson's disease. Image and caption information courtesy of the California Institute for Regenerative Medicine. Related to images 3270 and 3271.

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.

A cancer cell with three nuclei, shown in turquoise. The abnormal number of nuclei indicates that the cell failed to go through cell division, probably more than once. Mitochondria are shown in yellow, and a protein of the cell’s cytoskeleton appears in red. This video was captured using a confocal microscope.

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.

This video shows a controlled outbreak of transmissible avian flu among people living in Thailand. Red indicates areas of infection while blue indicates areas where a combination of control measures were implemented. The video shows how control measures contained the infection in 90 days, before it spread elsewhere.