A glowing zebrafish wins the 2020 Nikon Small World photography contest

The annual competition brings some of Earth’s smallest marvels to light

zebrafish

To study a zebrafish's lymphatic system, scientists genetically modified the fish to have bones and scales that fluoresce blue and lymphatic vessels that glow orange under certain types of light.

D. Castranova, B. Weinstein and B. Samasa/NIH, Nikon Small World

While seeking answers to scientific questions, it’s worth sometimes taking a step back to appreciate the world’s exquisiteness.

For developmental biologists Daniel Castranova, Bakary Samasa and Brant Weinstein, some of that delicate beauty is inside a zebrafish. While working in Weinstein’s lab at the National Institutes of Health in Bethesda, Md., Castranova and Samasa snapped a stunning photograph of a young zebrafish, illuminating never-before-seen parts of its lymphatic system.

The photo comes from research that sought to determine whether zebrafish have lymphatic vessels inside their skulls. The lymphatic system helps clear toxins and waste from the body, and previously researchers thought only mammals had such structures close to the brain.

But zebrafish have those vessels too, Castranova and colleagues report in preliminary research posted in May at bioRxiv.org. The team used fish that had been genetically modified to have lymphatic vessels that fluoresce orange under certain conditions, with skeletons and scales that glow blue. Because fish are easier than mammals to raise and image in the lab, Castranova says, the finding could help scientists more easily study the role of the brain’s lymphatic system in neurological diseases like brain cancer or Alzheimer’s.

After taking the photo — a composite of 350 images taken with a confocal microscope — on a busy work day, “I never even looked at the picture for a couple of weeks,” Castranova says. “And then when I looked at it at some point post-data processing, I was like ‘Wow.’”

Even if it took Castranova a bit to appreciate what he had in hand, judges for the 2020 Nikon Small World photomicroscopy competition realized that it was a winner. The photo snagged first place in the 46th annual contest. The results were announced October 13.

Here are some our favorite photographs from this year’s competition.

Inside a clownfish egg

clownfish
A developing clownfish (Amphiprion percula) embryo won second place in the contest. The series of photos documents the embryo’s growth (from left to right) on day one, morning and evening of day three, day five and day nine.Daniel Knop/Natur und Tier-Verlag NTV

Over nine days, German photographer Daniel Knop watched an embryo grow from a striking golden yolk sac into a baby clownfish (Amphiprion percula) to produce this second place–winning photo.

The composite image, created by stacking together multiple photos that had been taken while the embryo was in motion, documents stages of the embryo’s development from left to right. The first egg shows the newly growing fish hours after fertilization, with a white cluster of extra sperm cells still on the outside of the egg. The subsequent embryos depict the fish twice on the third day of development (morning and evening), as well as the fifth and ninth days, hours before the fish hatched.

Tongue of a snail

snail tongue
This colorful depiction of part of a snail’s tongue, at 40 times magnification, shows its structure in three dimensions. Sections colored blue are farthest from the viewer and those colored hot pink are closest. The image placed third in the competition.Igor Siwanowicz/HHMI

When neurobiologist Igor Siwanowicz’s lab mate’s aquarium was taken over by freshwater snails, Siwanowicz decided to snap a photo of part of one snail’s tongue, earning him third place in the competition.

The appendage, magnified 40 times, was photographed in layers with a laser to reconstruct the tongue in three dimensions. The pieces closest to the viewer are colored hot pink; the farthest bits are blue. The tongue’s comblike projections scrape algae off of surfaces for food.

“I chose this image to show that in nature, beauty can be found in the most unexpected places, like a snail’s mouth,” says Siwanowicz, of the Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Va., and second-place winner in the 2019 contest (SN: 10/21/19).

Lab-grown hairs

skin organoid
Shown at 20 times magnification, this skin organoid (colored blue) sports human hair follicles (stubby projections) and nerves (red). The image earned an honorable mention.Karl Koehler and Jiyoon Lee/Boston Children’s Hospital & Harvard Medical School

Neuroscientist Karl Koehler and biochemist Jiyoon Lee, both of Boston Children’s Hospital and Harvard Medical School, captured this image of human hair follicles budding off of a cluster of lab-grown skin cells, broadly called an organoid, in a lab dish. Other types of organoids exist for various parts of the body, such as the gut and brain.  

It takes about four to five months for a skin organoid to grow in the lab. The structures develop nerves that connect specialized cells in hair follicles, much like the neural circuit system that allows us to feel touch, and could one day help develop better skin grafts. This lab-grown skin develops inside-out, Koehler says. So the surface that grows hair is inside the clump of cells, and viewers see the base of hair follicles. The team published their findings June 3 in Nature.

Majestic moss

skin organoid
Moss capsules, like the one pictured here at 10 times magnification and shown in false-color, release hundreds of thousands of spores that are carried by the wind to new parts of the forest to grow. The photo is an Image of Distinction in this year’s Nikon Small World photo contest.Miroslav Žít

Miroslav Žít, an amateur photographer from Prachatice in the Czech Republic, snapped this photo of a stunning moss capsule packed with spores almost ready to take flight. Capsules perch on top of stems that extend from blankets of moss.

The spores ride the wind once released, sometimes traveling long distances and staying dormant until conditions are right for growth.

Viral infection

mouse paw infected with Chikungunya virus
This mouse paw has been infected with the Chikungunya virus (colored pink at the bottom part of the paw), a pathogen that causes painful inflammation of the joints. The rodent’s immune response to the virus, in the form of immune cells called microphages, is shown in blue and general tissue is colored orange. The image won an honorable mention.Jonard Corpuz Valdoz, Pam Van Ry and Richard Robison/Brigham Young Univ.

Researchers at Brigham Young University in Provo, Utah combined more than 2,200 photos taken with a confocal microscope to create this vivid shot of a 1-centimeter-long mouse paw infected with the Chikungunya virus.

Chikungunya is a disease that can result in debilitating joint pain. Biochemists Jonard Corpuz Valdoz and Pam Van Ry teamed up with microbiologist Richard Robison to take a peek at how a mouse responds to the infection, in the hopes of shedding light on how the virus spreads in animals, including humans. The image shows that immune cells called macrophages have rushed to the paw to fight the virus.

Baby bat

fruit bat embryo
This image of a Seba’s short-tailed fruit bat embryo (Carollia perspicillata) is colored to show its skeleton in green and cartilage in orange; it placed 20th in the photo competition.Dorit Hockman/ Univ. of Cape Town, Vanessa Chong-Morrison/UCL

While participating in an embryology course at the Marine Biological Laboratory in Woods Hole, Mass., Vanessa Chong-Morrison, a developmental biologist then at the University of Oxford, prepared this image of a Seba’s short-tailed fruit bat (Carollia perspicillata) embryo for picture day.

Chong-Morrison, now at University College London, and Dorit Hockman of the University of Cape Town in South Africa took snapshots of the developing bat’s skeleton, capturing small areas at a time. Hockman is also a developmental biologist who studies how bat hands grow into “impressive wings.” The pair then stitched together the images to produce the final photo, which was edited to show the bat’s bones in green and cartilage in orange.   

A work of amino acid art

L-glutamine and beta-alanine crystals
When in a warm solution of ethanol and water, amino acids L-glutamine and beta-alanine form crystals, photographed here in a 13th place–winning photo at four times magnification.Justin Zoll/Justin Zoll Photography

No, this photo isn’t an abstract painting. It’s a portrait of the crystals that form after two amino acids — L-glutamine and beta-alanine — are heated in a solution made of ethanol and water. One of the compounds, L-glutamine, is a building block for proteins and ensures that the immune system can function. The other, beta-alanine, helps with muscle endurance.

Justin Zoll, a photographer based in Ithaca, N.Y., merged multiple images of crystals taken at four times their normal size into a panorama to show the crystals’ intricate details in a wider field of view. When the crystals interact with a multiple beams of polarized light, the arrangement of their molecules reflects stunning colors, he says.

Erin I. Garcia de Jesus is a staff writer at Science News. She holds a Ph.D. in microbiology from the University of Washington and a master’s in science communication from the University of California, Santa Cruz.