Visualizing Skin Regeneration in Real Time

Top: Colorful skin cells on a zebrafish . Bottom: Cells from the outer surface of the scale.
More than 70 Skinbow colors distinguish hundreds of live cells from a tiny bit (0.0003348 square inches) of skin on the tail fin of an adult zebrafish. The bottom image shows the cells on the outer surface of a scale. Credit: Chen-Hui Chen, Duke University.

Zebrafish, blue-and-white-striped fish that are about 1.5 inches long, can regrow injured or lost fins. This feature makes the small fish a useful model organism for scientists who study tissue regeneration.

To better understand how zebrafish skin recovers after a scrape or amputation, researchers led by Kenneth Poss of Duke University tracked thousands of skin cells in real time. They found that lifespans of individual skin cells on the surface were 8 to 9 days on average and that the entire skin surface turned over in 20 days.

The scientists used an imaging technique they developed called “Skinbow,” which essentially shows the fish’s outer layer of skin cells in a spectrum of colors when viewed under a microscope. Skinbow is based on a technique created to study nerve cells in mice, another model organism.

The research team’s color-coded experiments revealed several unexpected cellular responses during tissue repair and replacement. The scientists plan to incorporate additional imaging techniques to generate an even more detailed picture of the tissue regeneration process.

The NIH director showcased the Skinbow technique and these images on his blog, writing: “You can see more than 70 detectable Skinbow colors that make individual cells as visually distinct from one another as jellybeans in a jar.”

This work was funded in part by NIH under grant R01GM074057.

The Proteasome: The Cell’s Trash Processor in Action

Our cells are constantly removing and recycling molecular waste. On the occasion of Earth Day, we put together this narrated animation to show you one way cells process their trash. The video features the proteasome, a cellular machine that breaks down damaged or unwanted proteins into bits that the cell can re-use to make new proteins. For this reason, the proteasome is as much a recycling plant as it is a garbage disposal.

For more details about the proteasome and other cellular disposal systems, check out our article How Cells Take Out the Trash.

Another Piece to a Century-Old Evolutionary Puzzle

After mating about 55,000 pairs of fruit flies and sifting through 333,000 daughter flies, a research team found six sons that each had mutations in the same gene that helped make two fruit fly species unique from each other. Credit: Jim Woolace, Fred Hutch News Service.

Nitin Phadnis and Harmit Malik Exit icon set out to conduct an experiment that could solve a century-old evolutionary puzzle: How did two related fruit fly species arise from one? Years after they began their quest, they finally have an answer.

The existence of a gene that helps make each of these fruit fly species unique and separate from each other had been guessed at since 1940, following experiments decades earlier in which geneticists first noticed that the two types of flies, when mated, had only daughters—no sons.

Scientists had previously discovered two other genes involved in driving the fruit fly species apart, but they knew those two genes weren’t the full story. Continue reading

Finding Adventure: Blake Wiedenheft’s Path to Gene Editing

Blake Wiedenheft
Blake Wiedenheft
Grew up in: Fort Peck, Montana
Fields: Microbiology, biochemistry, structural biology
Job site: Montana State University
Secret talent: Being a generalist; enjoying many different subjects and activities
When not in the lab, he’s: Running, biking, skiing or playing scrabble with his grandmother

Scientific discoveries are often stories of adventure. This is the realization that set Blake Wiedenheft on a path toward one of the hottest areas in biology.

His story begins in Montana, where he grew up and now lives. Always exploring different interests, Wiedenheft decided in his final semester at Montana State University (MSU) in Bozeman to volunteer for Mark Young, a scientist who studies plant viruses. Even though he majored in biology, Wiedenheft had spent little time in a lab and hadn’t even considered research as a career option. Continue reading

New Views on What the Cell’s Parts Can Do

Studying some of the most well-tread territory in science can turn up surprising new findings. Take, for example, the cell. You may have read in textbooks how the cell’s parts look and function during important biological processes like cellular movement and division. You may have even built models of the cell out of gelatin or clay. But scientists continue to learn new facts that require those textbooks to be updated, and those models to be reshaped. Here are a few examples.

Nuclear Envelope: More Than a Protective Barrier

Damaged heterochromatin represented by nucleotides GCAT
Damaged heterochromatin, a tightly packed form of DNA, travels to the inner wall of the nuclear envelope for repair. Credit: Irene Chiolo and Taehyun Ryu, University of Southern California.

Like a security guard checking IDs at the door, the nuclear envelope forms a protective barrier around the cell’s nucleus, only letting specific proteins and chemical signals pass through. Scientists recently found that this envelope may also act as a repair center for broken strands of heterochromatin, a tightly packed form of DNA.

Irene Chiolo of the University of Southern California and Gary Karpen of the University of California, Berkeley, and the Lawrence Berkeley National Laboratory were part of a team that learned that healthy fruit fly cells mend breaks in heterochromatin by moving the damaged DNA strands to the inner wall of the nuclear envelope. There, proteins embedded in the envelope make the necessary repairs in a safe place where the broken DNA can’t accidentally get fused to the wrong chromosome. Continue reading