This colorful picture does not show a work of art by Andy Warhol, but rather the development of a zebrafish eye. In the top row, three-day-old eyes look out at the viewer; in the bottom row, the small zebrafish are already 15 days old. The picture impressively shows how quickly the eyes of zebrafish grow.
Zebrafish originally come from Pakistan, northern India, Nepal and Bangladesh, but are also very popular as aquarium fish because of their undemanding nature. Towards the end of the 1960s, scientists also discovered the potential of zebrafish as laboratory animals: around 70 percent of their genes match those of humans and around 80 percent of the genes that cause diseases in humans are also found in the genes of zebrafish. What also makes the small fish so interesting for science is that their larvae are transparent. This allows researchers to look inside the fish’s bodies without having to injure them.
This property has now also benefited researchers at the NYU Grossman School of Medicine. Paige Leary’s research team investigated the development of a brain reflex that allows animals and humans to stabilize their gaze during movements. The so-called vestibulo-ocular reflex compensates for head and body movements by moving the eyes reflexively and remaining focused on the object being viewed. Experts also refer to this eye movement as the doll’s head phenomenon: If a doll with sleeping eyes is laid down, its eyes close according to the tilt of its head.
The result: Contrary to what was previously assumed, the reflex apparently develops correctly even when the zebrafish is blind or does not receive signals from a balance organ – the utricle. Instead, the neuromuscular junctions influence the development of the vestibulo-ocular reflex, as the researchers found. “Discovering how vestibular reflexes arise could help us find new ways to treat diseases that affect balance or eye movement,” explains co-author David Schoppik.