Category: Molecular Structures

Through the Looking Glass: Microscopic Structures in Many Sizes

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We seldom see microscopic objects next to one another, so it can be difficult to picture how they compare. For instance, it might surprise you that a thousand cold-virus particles could line up across one human skin cell! The largest objects that scientists view through microscopes are about a millimeter (roughly the size of a poppyseed), and they’re about 10 million times larger than the smallest molecules scientists can view: atoms.

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Freezing a Moment in Time: Snapshots of Cryo-EM Research

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To get a look at cell components that are too small to see with a normal light microscope, scientists often use cryo-electron microscopy (cryo-EM). As the prefix cryo- means “cold” or “freezing,” cryo-EM involves rapidly freezing a cell, virus, molecular complex, or other structure to prevent water molecules from forming crystals. This preserves the sample in its natural state and keeps it still so that it can be imaged with an electron microscope, which uses beams of electrons instead of light. Some electrons are scattered by the sample, while others pass through it and through magnetic lenses to land on a detector and form an image.

Typically, samples contain many copies of the object a scientist wants to study, frozen in a range of orientations. Researchers take images of these various positions and combine them into a detailed 3D model of the structure. Electron microscopes allow us to see much smaller structures than light microscopes do because the wavelengths of electrons are much shorter than the wavelength of light. NIGMS-funded researchers are using cryo-EM to investigate a range of scientific questions.

Caught in Translation

One cluster that is yellow, purple, and orange and another that is beige, purple, and green. 3D reconstructions of two stages in the assembly of the bacterial ribosome created from time-resolved cryo-EM images. Credit: Joachim Frank, Columbia University.

Joachim Frank, Ph.D., a professor of biochemistry and molecular biophysics and of biological sciences at Columbia University in New York, New York, along with two other researchers, won the 2017 Nobel Prize in Chemistry for developing cryo.

Dr. Frank’s lab focuses on the process of translation, where structures called ribosomes turn genetic instructions into proteins, which are needed for many chemical reactions that support life. Recently, Dr. Frank has adopted and further developed a technique called time-resolved cryo-EM. This method captures images of short-lived states in translation that disappear too quickly (after less than a second) for standard cryo-EM to capture. The ability to fully visualize translation could help researchers identify errors in the process that lead to disease and also to develop treatments.

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Cool Images: The Hidden Beauty Inside Plants

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Spring brings with it a wide array of beautiful flowers, but the interior structures of plants can be just as stunning. Using powerful microscopes, researchers can peek into the many molecular bits and pieces that make up plants. Check out these cool plant images from our Image and Video Gallery that NIGMS-funded scientists created while doing their research.

Several round structures that are yellow at the center and pink and purple around the edges and have honeycomb-like interiors. Credit: Arun Sampathkumar and Elliot Meyerowitz, California Institute of Technology.

In plants and animals, stem cells can transform into a variety of different cell types. The stem cells at the growing tip of this Arabidopsis plant will soon become flowers. Cellular and molecular biologists frequently study Arabidopsis because it grows rapidly (its entire life cycle is only 6 weeks), produces lots of seeds, and has a genome that’s easy to manipulate.

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Twisting and Turning: Unraveling What Causes Asymmetry

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Note to our Biomedical Beat readers: Echoing the sentiments NIH Director Francis Collins made on his blog, NIGMS is making every effort during the COVID-19 pandemic to keep supporting the best and most powerful science. In that spirit, we’ll continue to bring you stories across a wide range of NIGMS topics. We hope these posts offer a respite from the coronavirus news when needed.

Asymmetry in our bodies plays an important role in how they work, affecting everything from function of internal systems to the placement and shape of organs. Take a look at your hands. They are mirror images of each other, but they’re not identical. No matter how you rotate them or flip them around, they will never be the same. This is an example of chirality, which is a particular type of asymmetry. Something is chiral if it can’t overlap on its mirror image.

An image of a pair of hands, palms facing up. An arrow points to another image of the left hand on top of the right, both palms still facing up, illustrating that they can’t be superimposed. Our hands are chiral: They’re mirror images but aren’t identical.

Scientists are exploring the role of chirality and other types of asymmetry in early embryonic development. Understanding this relationship during normal development is important for figuring out how it sometimes goes wrong, leading to birth defects and other medical problems.

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PECASE Honoree James Olzmann Investigates the Secrets of Lipid Droplets

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Note to our Biomedical Beat readers: Echoing the sentiments NIH Director Francis Collins made on his blog, NIGMS is making every effort during the COVID-19 pandemic to keep supporting the best and most powerful science. In that spirit, we’ll continue to bring you stories across a wide range of NIGMS topics. We hope these posts offer a respite from the coronavirus news when needed.

A large, blue oval surrounded by much smaller yellow circles. A cell nucleus (blue) surrounded by lipid droplets (yellow). Credit: James Olzmann.

Within our cells, lipids are often stored in droplets, membrane-bound packages of lipids produced by the endoplasmic reticulum. For many years, scientists thought lipid droplets were simple globs of fat and rarely studied them. But over the past few decades, research has revealed that they’re full-fledged organelles, or specialized structures that perform important cellular functions. The field of lipid droplet research has been growing ever since.

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Revealing a Piece of Cilia’s Puzzle

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A multicolored tube made up of small dots with three sets of appendages attached along its length. A partial model of a doublet microtubule. Credit: Veronica Falconieri.

Cilia (cilium in singular) are complex organelles found on all of our cells except red blood cells. Their rhythmic beating moves fluid or materials over the cell to help transport food and oxygen or remove debris. For example, cilia in our windpipe prevent bacteria and mucous from traveling to the lungs. Some pick up signals like antennae, such as cilia in our ears that help detect sounds. One component of cilia is the doublet microtubule, a major part of cilia’s skeleton that gives it strength and rigidity.

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Interview With a Scientist – Rommie Amaro: Computational and Theoretical Model Builder

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Many researchers who search for anti-cancer drugs have labs filled with chemicals and tissue samples. Not Rommie Amaro. Her work uses computers to analyze the shape and behavior of a protein called p53. Defective versions of p53 are associated with more human cancers than any other malfunctioning protein.

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Interview with a Scientist: Michael Summers, Using Nuclear Magnetic Resonance to Study HIV

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For more than 30 years, NIGMS has supported the structural characterization of human immunodeficiency virus (HIV) enzymes and viral proteins. This support has been instrumental in the development of crucial drugs for antiretroviral therapy such as protease inhibitors. NIGMS continues to support further characterization of viral proteins as well as cellular and viral complexes. These complexes represent the fundamental interactions between the virus and its host target cell and, as such, represent potential new targets for therapeutic development.

In this third in a series of three video interviews with NIGMS-funded researchers probing the structure of HIV, Michael Summers,Link to external web site professor of biochemistry at the University of Maryland, Baltimore County, discusses his use of nuclear magnetic resonance (NMR) technology to study HIV. Of recent interest to Summers has been using NMR to investigate how HIV’s RNA enables the virus to reproduce. His goals for this line of research are to develop treatments against HIV as well as learning how to best engineer viruses to deliver helpful therapies to individuals with a variety of diseases.

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