Scientists have transformed yellow mutant zebrafish into a standard type of fish with a light yellow hue and dark stripes by inserting pigment-producing genes into the embryos.
In an intriguing “trick,” they discovered that when they inserted a similar pigment gene found in humans into the fish, they also changed color in a similar manner.
As with humans, the color of zebrafish is determined by pigment cells, which contain pigment granules known as melanosomes. The number, size, and darkness of the melanosome granules in each pigment cell affect its color. For instance, Europeans have fewer melanosomes, which are also smaller and lighter compared to those of West Africans, while Asians fall somewhere in between these two groups.
The yellow zebrafish have fewer, smaller, and lighter melanosome granules compared to normal fish.
The Experiment
Keith Cheng from Pennsylvania State University and his team found that a mutation in a gene (which causes it to malfunction) prevented the zebrafish from producing the necessary protein to create pigment granules.
“A gene mutation halts the protein production machine,” Cheng stated.
However, when Cheng’s team inserted a correct version of the aforementioned gene into two-day-old yellow zebrafish embryos, the fish began to produce melanosomes, restoring their familiar dark color in just a few days.
Next, the research team explored HapMap, an online database of human genetic profiles, and discovered a similar melanosome-producing gene in humans. Thus, they tested this gene by inserting it into the yellow zebrafish embryos, and they also returned to their familiar dark color.
“We speculate that the zebrafish darkened due to the similar function of the implanted human gene – genes that produce more, larger, and darker melanosomes,” Cheng explained.
Mutations in Humans
Similar to yellow zebrafish, light-skinned Europeans also possess a mutation in the melanosome-producing gene, resulting in less pigmentation in their skin. Scientists speculate that the diversity of this gene may also contribute to the occurrence of blue eyes and light hair in some individuals.
However, Cheng noted that it is important to understand that the mutations in humans and zebrafish are different – while the gene in zebrafish completely fails to produce the protein needed for melanosome creation, the mutated gene in humans still functions, albeit less actively.
This discovery could lead to advancements in targeting malignant pigment tumors or in research on how to alter skin color without using chemicals or other damaging solutions.
Thuan An