Actin gliding powered by myosin 1D. Note the counterclockwise motion of the gliding actin filaments.

Georgia Tech associate professor Hang Lu holds a microfluidic chip that is part of a system that uses artificial intelligence and cutting-edge image processing to automatically examine large number of nematodes used for genetic research.

Los ritmos circadianos son cambios físicos, mentales y conductuales que siguen un ciclo de 24 horas. Los ritmos circadianos típicos conducen a un nivel alto de energía durante la mitad del día (de 10 a.m. a 1 p.m.) y un bajón por la tarde. De noche, los ritmos circadianos hacen que la hormona melatonina aumente, lo que hace que la persona se sienta somnolienta.

Vea 6611 para la versión en inglés de esta infografía.

Human cells with the gene that codes for the protein FIT2 deleted. After an experimental intervention, they are expressing a nonfunctional version of FIT2, shown in green. The lack of functional FIT2 affected the structure of the endoplasmic reticulum (ER), and the nonfunctional protein clustered in ER membrane aggregates, seen as large bright-green spots. Lipid droplets are shown in red, and the nucleus is visible in gray. This image was captured using a confocal microscope. Related to image 6773.

Protein kinases—enzymes that add phosphate groups to molecules—are cancer chemotherapy targets because they play significant roles in almost all aspects of cell function, are tightly regulated, and contribute to the development of cancer and other diseases if any alterations to their regulation occur. Genetic abnormalities affecting the c-Abl tyrosine kinase are linked to chronic myelogenous leukemia, a cancer of immature cells in the bone marrow. In the noncancerous form of the protein, binding of a myristoyl group to the kinase domain inhibits the activity of the protein until it is needed (top left shows the inactive form, top right shows the open and active form). The cancerous variant of the protein, called Bcr-Abl, lacks this autoinhibitory myristoyl group and is continually active (bottom). ATP is shown in green bound in the active site of the kinase.

Find these in the RCSB Protein Data Bank: c-Abl tyrosine kinase and regulatory domains (PDB entry 1OPL) and F-actin binding domain (PDB entry 1ZZP).

Model based on X-ray crystallography of the structure of a small heat shock protein complex from the bacteria, Methanococcus jannaschii. Methanococcus jannaschii is an organism that lives at near boiling temperature, and this protein complex helps it cope with the stress of high temperature. Similar complexes are produced in human cells when they are "stressed" by events such as burns, heart attacks, or strokes. The complexes help cells recover from the stressful event.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. 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). In this frame (2 of 4), the CRISPR machine locates the target DNA sequence once inserted into a cell.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video, and find the full CRIPSR illustration here.

This transmission electron micrograph shows sections of mouse sperm tails, or flagella.

RNA interference or RNAi is a gene-silencing process in which double-stranded RNAs trigger the destruction of specific RNAs. See 2559 for a labeled version of this illustration. Featured in The New Genetics.

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 fruit fly ovary, shown here, contains as many as 20 eggs. Fruit flies are not merely tiny insects that buzz around overripe fruit—they are a venerable scientific tool. Research on the flies has shed light on many aspects of human biology, including biological rhythms, learning, memory, and neurodegenerative diseases. Another reason fruit flies are so useful in a lab (and so successful in fruit bowls) is that they reproduce rapidly. About three generations can be studied in a single month.

Related to image 3656. This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Related to image 6355.

Real-time movie of young squids. Squids are often used as research organisms due to having the largest nervous system of any invertebrate, complex behaviors like instantaneous camouflage, and other unique traits.

This video was taken with polychromatic polarization microscope, as described in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak. The color is generated by interaction of white polarized light with the squid’s transparent soft tissue. The tissue works as a living tunable spectral filter, and the transmission band depends on the molecular orientation. When the young squid is moving, the tissue orientation changes, and its color shifts accordingly.

Damage to each person's genome, often called the "Book of Life," accumulates with time. Such DNA mutations arise from errors in the DNA copying process, as well as from external sources, such as sunlight and cigarette smoke. DNA mutations are known to cause cancer and also may contribute to cellular aging.

A representation of a patient’s brain waves after receiving the anesthetic propofol. All anesthetics create brain wave changes that vary depending on the patient’s age and the type and dose of anesthetic used. These changes are visible in raw electroencephalogram (EEG) readings, but they’re easier to interpret using a spectrogram where the signals are broken down by time (x-axis), frequency (y-axis), and power (color scale). This spectrogram shows the changes in brain waves before, during, and after propofol-induced anesthesia. The patient is unconscious from minute 5, upon propofol administration, through minute 69 (change in power and frequency). But, between minutes 35 and 48, the patient fell into a profound state of unconsciousness (disappearance of dark red oscillations between 8 to 12 Hz), which required the anesthesiologist to adjust the rate of propofol administration. The propofol was stopped at minute 62 and the patient woke up around minute 69.

The green spots in this image are clumps of protein inside yeast cells that are deficient in both zinc and a protein called Tsa1 that prevents clumping. Protein clumping plays a role in many diseases, including Parkinson's and Alzheimer's, where proteins clump together in the brain. Zinc deficiency within a cell can cause proteins to mis-fold and eventually clump together. Normally, in yeast, Tsa1 codes for so-called "chaperone proteins" which help proteins in stressed cells, such as those with a zinc deficiency, fold correctly. The research behind this image was published in 2013 in the Journal of Biological Chemistry.

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.

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.

Shiga toxin (green) is sorted from the endosome into membrane tubules (red), which then pinch off and move to the Golgi apparatus.

This structure from an amyloid-forming prion protein shows one way beta sheets can stack. Image originally appeared in a December 2012 PLOS Biology paper.

Cell showing overproduction of the ARTS protein (red). ARTS triggers apoptosis, as shown by the activation of caspase-3 (green) a key tool in the cell's destruction. The nucleus is shown in blue. Image is featured in October 2015 Biomedical Beat blog post Cool Images: A Halloween-Inspired Cell Collection.

A global "map of the protein structure universe" indicating the positions of specific proteins. The preponderance of small, less-structured proteins near the origin, with the more highly structured, large proteins towards the ends of the axes, may suggest the evolution of protein structures.

This Petri dish contains microscopic roundworms called Caenorhabditis elegans. Researchers used these particular worms to study how C. elegans senses the color of light in its environment.

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.

Enzymes speed up chemical reactions by reducing the amount of energy needed for the reactions. The substrate (lactose) binds to the active site of the enzyme (lactase) and is converted into products (sugars).

Fourteen neurons (magenta) in the adult Drosophila brain produce insulin, and fat tissue sends packets of lipids to the brain via the lipoprotein carriers (green). This image was captured using a confocal microscope and shows a maximum intensity projection of many slices.

Related to images 6983, 6984, and 6985.

Actin is an essential protein in a cell's skeleton (cytoskeleton). It forms a dense network of thin filaments in the cell. Here, researchers have used a technique called stochastic optical reconstruction microscopy (STORM) to visualize the actin network in a cell in three dimensions. The actin strands were labeled with a dye called Alexa Fluor 647-phalloidin.  This image appears in a study published by Nature Methods, which reports how researchers use STORM to visualize the cytoskeleton.

Each morning, the nocturnal Hawaiian bobtail squid, Euprymna scolopes, hides from predators by digging into the sand. At dusk, it leaves the sand again to hunt.

Related to image 7010 and 7011.

Image showing that the edge zone (top of image) of the quail embryo shows no proliferating cells (cyan), unlike the interior zone (bottom of image). Non-proliferating cell nuclei are labeled green. This image was obtained as part of a study to understand cell migration in embryos. More specifically, cell proliferation at the edge of the embryo was studied by examining the cellular uptake of a chemical compound called BrDU, which incorporates into the DNA during the S-phase of the cell cycle. Here, the cells that are positive for BrDU uptake are labeled in cyan, while other non-proliferating cell nuclei are labeled green. Notice that the vast majority of BrDU+ cells are located far away from the edge, indicating that edge cells are mostly non-proliferating. An NIGMS grant to Professor Garcia was used to purchase the confocal microscope that collected this image. Related to image 2807 and video 2809.

Haplotypes are combinations of gene variants that are likely to be inherited together within the same chromosomal region. In this example, an original haplotype (top) evolved over time to create three newer haplotypes that each differ by a few nucleotides (red). See image 2566 for an unlabeled version of this illustration. Featured in The New Genetics.

This image of the human brain uses colors and shapes to show neurological differences between two people. The blurred front portion of the brain, associated with complex thought, varies most between the individuals. The blue ovals mark areas of basic function that vary relatively little. Visualizations like this one are part of a project to map complex and dynamic information about the human brain, including genes, enzymes, disease states, and anatomy. The brain maps represent collaborations between neuroscientists and experts in math, statistics, computer science, bioinformatics, imaging, and nanotechnology.

Microtubules (magenta) and tau protein (light blue) in a cell model of tauopathy. Researchers believe that tauopathy—the aggregation of tau protein—plays a role in Alzheimer’s disease and other neurodegenerative diseases. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6889, 6890, and 6891.

The green spots in this mouse brain are cells labeled with Calling Cards, a technology that records molecular events in brain cells as they mature. Understanding these processes during healthy development can guide further research into what goes wrong in cases of neuropsychiatric disorders. Also fluorescently labeled in this image are neurons (red) and nuclei (blue). Calling Cards and its application are described in the Cell paper “Self-Reporting Transposons Enable Simultaneous Readout of Gene Expression and Transcription Factor Binding in Single Cells” by Moudgil et al.; and the Proceedings of the National Academy of Sciences paper “A viral toolkit for recording transcription factor–DNA interactions in live mouse tissues” by Cammack et al. The technology was also featured in the NIH Director’s Blog post The Amazing Brain: Tracking Molecular Events with Calling Cards.

Related to video

Mosquito larvae with genes edited by CRISPR. This species of mosquito, Culex quinquefasciatus, can transmit West Nile virus, Japanese encephalitis virus, and avian malaria, among other diseases. The researchers who took this image developed a gene-editing toolkit for Culex quinquefasciatus that could ultimately help stop the mosquitoes from spreading pathogens. The work is described in the Nature Communications paper "Optimized CRISPR tools and site-directed transgenesis towards gene drive development in Culex quinquefasciatus mosquitoes" by Feng et al. Related to image 6769 and video 6771.

Molecular biologists are increasingly relying on bioinformatics software to visualize molecular interaction networks and to integrate these networks with data such as gene expression profiles. Related to 2749.

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.

This is a super-resolution light microscope image taken by Hiro Hakozaki and Masa Hoshijima of NCMIR. The image contains highlighted calcium channels in cardiac muscle using a technique called dSTORM. The microscope used in the NCMIR lab was built by Hiro Hakozaki.

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) and DAPI to visualize the nucleus (blue). ARPC3+/+ fibroblast cells with lamellipodia leading edge. Related to images 3328, 3329, 3330, 3331, and 3333.

Viruses have been the foes of animals and other organisms for time immemorial. For almost as long, they've stayed well hidden from view because they are so tiny (they aren't even cells, so scientists call the individual virus a "particle"). This image shows a molecular model of a particle of the Rous sarcoma virus (RSV), a virus that infects and sometimes causes cancer in chickens. In the background is a photo of red blood cells. The particle shown is "immature" (not yet capable of infecting new cells) because it has just budded from an infected chicken cell and entered the bird's bloodstream. The outer shell of the immature virus is made up of a regular assembly of large proteins (shown in red) that are linked together with short protein molecules called peptides (green).  This outer shell covers and protects the proteins (blue) that form the inner shell of the particle. But as you can see, the protective armor of the immature virus contains gaping holes. As the particle matures, the short peptides are removed and the large proteins rearrange, fusing together into a solid sphere capable of infecting new cells. While still immature, the particle is vulnerable to drugs that block its development. Knowing the structure of the immature particle may help scientists develop better medications against RSV and similar viruses in humans. Scientists used sophisticated computational tools to reconstruct the RSV atomic structure by crunching various data on the RSV proteins to simulate the entire structure of immature RSV.

A three-dimensional representation of the structure of E2, a key antigen protein involved with hepatitis C virus infection.

This image shows an osteosarcoma cell with DNA in blue, energy factories (mitochondria) in yellow, and actin filaments—part of the cellular skeleton—in purple. One of the few cancers that originate in the bones, osteosarcoma is rare, with about a thousand new cases diagnosed each year in the United States.

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

Like a pulsing blue shower, E. coli cells flash in synchrony. Genes inserted into each cell turn a fluorescent protein on and off at regular intervals. When enough cells grow in the colony, a phenomenon called quorum sensing allows them to switch from blinking independently to blinking in unison. Researchers can watch waves of light propagate across the colony. Adjusting the temperature, chemical composition or other conditions can change the frequency and amplitude of the waves. Because the blinks react to subtle changes in the environment, synchronized oscillators like this one could one day allow biologists to build cellular sensors that detect pollutants or help deliver drugs.

DNA encodes RNA, which encodes protein. DNA is transcribed to make messenger RNA (mRNA). The mRNA sequence (dark red strand) is complementary to the DNA sequence (blue strand). On ribosomes, transfer RNA (tRNA) reads three nucleotides at a time in mRNA to bring together the amino acids that link up to make a protein. See image 2549 for a numbered version of this illustration and 2547 for an unlabeled version. Featured in The New Genetics.

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.

Flower development is a carefully orchestrated, genetically programmed process that ensures that the male (stamen) and female (pistil) organs form in the right place and at the right time in the flower. In this image of young Arabidopsis flower buds, the gene SUPERMAN (red) is activated at the boundary between the cells destined to form the male and female parts. SUPERMAN activity prevents the central cells, which will ultimately become the female pistil, from activating the gene APETALA3 (green), which induces formation of male flower organs. The goal of this research is to find out how plants maintain cells (called stem cells) that have the potential to develop into any type of cell and how genetic and environmental factors cause stem cells to develop and specialize into different cell types. This work informs future studies in agriculture, medicine and other fields.

The nucleus of a human fibroblast cell with chromatin—a substance made up of DNA and proteins—shown in various colors. Fibroblasts are one of the most common types of cells in mammalian connective tissue, and they play a key role in wound healing and tissue repair. This image was captured using Stochastic Optical Reconstruction Microscopy (STORM).

Related to images 6887 and 6893.

Borrelia burgdorferi is a spirochete, a class of long, slender bacteria that typically take on a coiled shape. Infection with this bacterium causes Lyme disease.

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.

Cell mopping up.

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 3792.