Category: Cells

Science Snippet: Apoptosis Explained

0 comments

Apoptosis is the process by which cells in the body die in a controlled and predictable way because they have DNA damage or are no longer needed. The term comes from a Greek word meaning “falling off,” as in leaves falling from a tree.

When a cell undergoes apoptosis, it shrinks and pulls away from its neighbors. As the cytoskeleton that gives it shape and structure collapses, the envelope around the cell’s nucleus breaks down, and its DNA breaks into pieces. Its surface changes, signaling its death to other cells and leading a healthy cell to engulf the dying one and recycle its components.

On the left, two large cells with clear, smooth edges. On the right, two smaller cells with ragged edges.
Two cells in a healthy state (left) and entering apoptosis (right). Credit: Hogan Tang of the Denise Montell Lab, Johns Hopkins School of Medicine.
Continue reading “Science Snippet: Apoptosis Explained”

Cool Video: A Biological Lava Lamp

1 comment
Several spheres contorting and lighting up inside a cone-shaped structure.
Credit: Jasmin Imran Alsous and Jonathan Jackson, Martin Lab, Massachusetts Institute of Technology.

What looks like a bubbling lava lamp is actually part of an egg cell’s maturation process. In many animals, the egg cell develops alongside sister cells. These sister cells are called nurse cells in the fruit fly (Drosophila melanogaster), and their job is to “nurse” an immature egg cell, or oocyte. Toward the end of oocyte development, the nurse cells transfer all their contents into the oocyte in a process called nurse cell dumping. This video captures this transfer, showing significant shape changes on the part of the nurse cells (blue), which are powered by wavelike activity of the protein myosin (red).

Researchers created the video using a confocal laser scanning microscope. Learn about this type of microscope and other scientific imaging tools by stepping into our virtual imaging lab, and check out more basic science videos and photos in the NIGMS Image and Video Gallery.

Career Conversations: Q&A with Molecular Biologist Hong Liu

0 comments
A scientist wearing a lab coat and holding a pipette in front of a workbench with scientific instruments.
Dr. Hong Liu in the lab.
Credit: Courtesy of Dr. Hong Liu.

“A scientific career is really worth it,” says Hong Liu, Ph.D., an assistant professor of biochemistry and molecular biology at Tulane University School of Medicine in New Orleans, Louisiana. Check out the highlights of our interview with Dr. Liu below to learn about his journey as a scientist and his advice for students.

Q: What makes a career in science exciting?

A: I think there are at least two things that make a science career very exciting. The first is that doing science means you have freedom to explore a lot of new ideas. The second thing is it’s rewarding. The “rewarding” I’m talking about here is not like how much money you can make. It’s rewarding in the answers you find and the new knowledge you reveal.

Continue reading “Career Conversations: Q&A with Molecular Biologist Hong Liu”

A Focus on Microscopes: See Eye-Catching Images

2 comments

Have you ever wondered what creates striking images of cells and other tiny structures? Most often, the answer is microscopes. Many of us have encountered basic light microscopes in science classes, but those are just one of many types that scientists use. Check out the slideshow to see images researchers have captured using different kinds of microscopes. For even more images of the microscopic world, visit the NIGMS Image and Video Gallery.

Visualizing Structures

Type of Microscope: Dark field
Used to Study: Living and dead cells

Oblong bacteria glowing blue on a black background.
Anthrax bacteria being killed by an agent that naturally glows blue when excited by ultraviolet light in the microscope.
Credit: Keiler Lab, Penn State University.

Type of Microscope: Time lapse
Used to Study: Living cells as they move over time

Cell-like compartments spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm. Endoplasmic reticulum (red) and microtubules (green) are also visible.
A dividing cell of an African globe lily. This is one frame of a time-lapse sequence that shows cell division in progress.
Credit: Andrew S. Bajer, University of Oregon, Eugene.

Type of Microscope: Super resolution light
Used to Study: Activity in living cells

Oblong blue structures with red threads connected to them on the left and right.
DNA (blue) being pulled apart by microtubules (red) as a cell divides. The blue and red colors are due to the fluorescent label used to dye the sample.
Credit: Jane Stout and Claire Walczak, Indiana University.

Type of Microscope: Fluorescent light
Used to Study: Activity in dyed cells and molecules

Many spots and swirls of fluorescent green and purple.
Kidney tissue stained with fluorescent dyes that glow under high intensity light from the microscope.
Credit: Tom Deerinck and Mark Ellisman, NCMIR.

Type of Microscope: Confocal
Used to Study: 3D images of living cells

Round green-yellow structures with red edges and blue dots in their centers.
Cell-like compartments that spontaneously emerge from scrambled frog eggs, with nuclei (blue) from frog sperm.
Credit: Xianrui Cheng, Stanford University School of Medicine. Xianrui Cheng, James E. Ferrell Jr. SCIENCE 366: 631, 01 Nov 2019 (DOI: 10.1126/science.aav7793).

Type of Microscope: Electron
Used to Study: Dead cells

A circle containing many types of structures an inner circle that is clear.
Cross-section through the worm, C. elegans, revealing various internal structures frozen in time. This image was taken with transmission electron microscopy and labeled afterwards with color to highlight features in the image.
Credit: Piali Sengupta, Brandeis University.

Type of Microscope: Cryo-EM
Used to Study: Cellular components, particles (viruses, molecules, ribosomes)

An oblong capsule made up of tiny gray, yellow, and red structures.
The protein shell, or capsid, that surrounds HIV and is covered in a host protein (red), which allows the virus to evade detection.
Credit: Juan R. Perilla, Klaus Schulten, and the Theoretical and Computational Biophysics Group.

Career Conversations: Q&A with Microbiologist Josephine Chandler

0 comments

Josephine (Josie) Chandler, Ph.D., first became interested in science when she took a high school chemistry class. In college, she fell in love with microbiology and ultimately earned a Ph.D. in the field. Today, she’s an associate professor of molecular biosciences at the University of Kansas in Lawrence, where her lab investigates interactions in bacterial communities. By better understanding these interactions, scientists may find new ways to stop infections or break down environmental pollutants—a process known as bioremediation.

Continue reading “Career Conversations: Q&A with Microbiologist Josephine Chandler”

Science Snippet: Learn About the Cytoskeleton

0 comments
A treelike structure made up of red and green fibers.
A cow cell showing actin filaments (red) and microtubules (green). Credit: Tina Carvalho, University of Hawaii at Manoa.

The cytoskeleton is a collection of fibers that gives shape and support to cells, like the skeleton does for our bodies. It also allows movement within the cell and, in some cases, by the entire cell. Three different types of fibers make up the cytoskeleton: actin filaments, intermediate filaments, and microtubules.

Powering Muscles

Actin filaments contract or lengthen to give cells the flexibility to move and change shape. Along with the protein myosin, they’re responsible for muscle contraction, including voluntary movement and involuntary muscle contractions, such as our heartbeats. Actin filaments are the thinnest and most brittle of the cytoskeletal fibers, but they’re also the most versatile in terms of shape.

Continue reading “Science Snippet: Learn About the Cytoskeleton”

Cool Images: Wondrous Worms

0 comments

The tiny roundworm Caenorhabditis elegans is one of the most common research organisms—creatures scientists use to study life. While C. elegans may seem drastically different from humans, it shares many genes and molecular pathways with us. Viewed with a microscope, the worm can also be surprisingly beautiful. Aside from the stunning imagery, these examples from our Image and Video Gallery show how C. elegans helps scientists advance our understanding of living systems and find new ways to improve our health.

Round yellow shapes with smaller blue spots. Three of the yellow shapes are connected by a purple line. Credit: Keir Balla and Emily Troemel, University of California San Diego.

This C. elegans has been infected with microsporidia (purple), parasites closely related to fungi. The yellow shapes are the worm’s gut cells, and the blue dots are nuclei. Some microsporidia can infect people, so studying the parasites in worms could help researchers devise strategies to prevent or treat infections.

Continue reading “Cool Images: Wondrous Worms”

Engage Learners in Science and Health With Our Kahoots!

0 comments

NIGMS, in collaboration with Scholastic, has developed a collection of free biology and health activities on the educational app Kahoot! You can play them alone, with friends, or with a class of students. Four Kahoots! are currently available:

Continue reading “Engage Learners in Science and Health With Our Kahoots!”

Take a Tour of Your Cells’ Organelles!

0 comments
An illustration of a cell cut in half, showing many different structures. A cross-section of a cell showing organelles. Credit: Judith Stoffer.

Welcome to our tour of the cell! Imagine you’ve shrunk down to about 3 millionths of your normal size. You are now about 0.5 micrometers tall (a micrometer is 1/1,000th of a millimeter). At this scale, a medium-sized human cell looks as long, high, and wide as a football field. But you can’t see nearly that far. Clogging your view is a rich stew of molecules, fibers, and various cell structures called organelles. Like the internal organs in your body, organelles in the cell each have a unique biological role to play.

The Nucleus and Its Closest Neighbor

Our first stop is the somewhat spherical structure about 50 feet in diameter. It’s the nucleus—basically the cell’s brain. The nucleus is the most prominent organelle and can occupy up to 10 percent of the space inside a cell. It contains the equivalent of the cell’s genetic material, or DNA.

Continue reading “Take a Tour of Your Cells’ Organelles!”

Quiz: Prove Your Knowledge of Proteins!

8 comments

Proteins play a role in virtually every activity in the body. They make up hair and nails, help muscles move, protect against infection, and more. Many NIGMS-funded researchers study the rich variety of proteins in humans and other organisms to shed light on their roles in health and disease.

Take our quiz to test how much you know about proteins. Afterward, find more quizzes and other fun learning tools on our activities and multimedia webpage, which includes an interactive protein alphabet.

Continue reading “Quiz: Prove Your Knowledge of Proteins!”