Scientists have transformed mutant zebrafish with yellow coloration into a standard fish with a pale yellow body and dark stripes by inserting pigment-producing genes into the embryos.
In an intriguing “trick,” they discovered that when a similar pigment gene found in humans was inserted into the fish, they changed color in a similar way.
Just like in humans, the skin color of zebrafish is determined by pigment cells, which contain pigment granules known as melanosomes. The number, size, and darkness of the melanosomes in each pigment cell affect its skin color. For example, 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 than normal fish.
The Experiment
Keith Cheng from Pennsylvania State University and his colleagues found that a mutation in a gene (which caused it to malfunction) prevented the zebrafish from producing the necessary protein to create pigment granules.
“A gene mutation stops the machine that produces the protein,” Cheng said.
However, when Cheng’s team inserted a correct version of the aforementioned gene into two-day-old yellow zebrafish embryos, they began producing melanosomes, allowing their skin color to revert to the familiar dark hue within 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. Therefore, they tested this gene by inserting it into the yellow zebrafish embryos, and they too returned to their familiar dark color.
“We hypothesize that the zebrafish darkened due to the similar function of the inserted human gene – those genes that produce more, larger, and darker melanosomes,” Cheng explained.
Mutations in Humans
Similar to the yellow zebrafish, light-skinned Europeans also have a mutation in the melanosome-producing gene, resulting in less pigment in their skin. Scientists speculate that the diversity of this gene may also be responsible for 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, just not as effectively.
This discovery could lead to advancements in targeting malignant pigment tumors or in studies exploring how to alter skin color without using chemicals or other harmful methods.
Thuan An
