Pretty picture or research breakthrough? It’s both

Alum’s photomicroscopy is art and science featured on a new Forever® Stamp

Daniel Castranova ('03) with a sheet of Forever Stamps featuring his zebrafish photo which can be seen in the background.

Image Credit: Courtesy Daniel Castranova

September 11, 2023 Kimbra Cutlip

Browsing the U.S. Postal Service’s latest release of Forever stamps is truly like a dive through Alice’s magnified Wonderland. From a detailed view of a beetle’s foot to mushroom gills and a knotted strand of human hair, the stamps reveal the beauty and magnificence of life at the smallest scale. That’s part of the appeal of photomicroscopy for Daniel Castranova (’03 MSc. Animal & Avian Sciences) whose image of a juvenile zebrafish is one of 20 featured in the Life Magnified stamp pane released in August.

As a senior research assistant at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health (NIH), Castranova studies intricate biological systems in fish that are similar in humans and can be used to advance medical science. To capture the striking photo, Castranova used zebrafish that have been specially developed in the lab to express different fluorescent colors in different body tissues. He snapped more than 350 different images at varying depths through the animal’s body. Then he compiled the images into a 3-D model that resembles an iridescent glass ornament with shimmery blue scales and bones interlaced with a network of orange vein-like vessels.

As beautiful as it is, the image also represents a revolutionary discovery, because those lacy orange vessels aren’t veins, they’re lymphatic vessels. They carry bodily fluids, including immune cells, disease surveillance cells and waste products, from organs and tissues, and no one knew they existed in fish skulls until Castranova’s photographs revealed them.

Castranova conducts research on blood and lymphatic vessel growth and development in the lab of NIH’s Dr. Brant Weinstein, where he landed his first job after grad school 20 years ago.

“I was a fish guy when I came to UMD,” Castranova recalled. “I had a B.S. in marine science, and I wanted to work in aquaculture. When I found professor Curry Woods (now retired), I moved to Animal Sciences and helped him build the aquaculture facility there.”

While Castranova was finishing up his master’s thesis, an AGNR alum who was working at NIH recommended him for a contracting position with the lab’s aquaculture facilities, and it was a perfect fit.

In addition to his other duties, Castranova still manages the zebrafish colonies, which are critical to the lab’s research. Zebrafish have many of the same structures and biological features as humans, and they share 71% of our genome. With an added benefit of having transparent embryos and a transparent lab-grown adult variety, the fish make perfect models for studying many human systems and diseases. And that’s why Castranova was imaging their lymphatic vessels.

In humans, those vessels may play a role in diseases where immune dysfunction harms the brain, like Multiple Sclerosis, Alzheimer’s, and brain cancer. The recognition that they also exist in zebrafish skulls opens up a new avenue for exploring potential causes and treatments for brain diseases.

Castranova’s research was published in a scientific paper in the journal Circulation Research, which featured one of his images on its cover. In 2020, one of his zebrafish images beat out thousands of others from around the world to win the top honor in the 46th annual Nikon Small World Photomicrography Competition. Castranova’s video of the first 22 hours of a zebrafish embryo’s development also won honorable mention that year.

It’s no accident that his photomicroscopy has received such accolades. He humbly rebuffs the idea that he is a photographer, but he admits to a photography hobby stretching back to his high school days, and says he believes in the value of a beautiful image to convey a message, be it scientific or artistic.

“When I took that image, I mostly needed a series of close-ups for research on when and where lymphatic vessels form,” he said. “But I thought it would be nice to have an overview picture of the whole fish, and I knew the way the pectoral fins spread like wings would look cool.”

After processing the images, he realized it was a beautiful picture, but Castranova has been surprised by its long-lived success. When the Post Office first contacted him, he wasn’t sure it was a legitimate request, so he sent the email to his communication’s office for confirmation. Now that the stamp is in print, he jokes that his parents are funding the U.S. Postal Service with all their stamp purchases. And he’s received a card in the mail from his mother-in-law posted with his stamp.

"That’s a pretty awesome feeling,” he said. And proof that taking an extra second to add artistry to his science is worth the effort.

Check out this cool virtual tour of the NIH Zebrafish Research Section featuring Daniel Castranova’s work:

And this video by Hank Green about the image featured in this story: