Zebrafish are a type of freshwater fish that belong to the family of carp and small fish. Today they are a widely used model organism in biomedical research.
When University of Ottawa biologists Kim Mitchell and Vance Trudeau began studying the effects of genetic mutations in zebrafish, they discovered new functions that regulate how males and females interact during mating. Specifically, the researchers used gene editing techniques to mutate two genes from these animals, and studied the effects on sexual function.
By changing the secretgranin-2 genes through a specific mutation, they found that this edit affected the reproductive ability of both males and females: it severely reduced their sexual behavior, to the point where both sexes were practically ignored , as the professor explains. Trudeau in an interview for the University of Ottawa.
Under normal parameters, a few minutes after a male and female are first introduced, the male chases the female in a courtship ritual; shortly after, they spawn, that is, the female releases her eggs into the water, and the male fertilizes them instantly. But the researchers found that only one in 10 of the gene-mutated couples were eventually able to father. This is the first evidence that the mutation of these genes leads to the disruption of sexual behavior in an animal.
Secretogranin-2 is a very important protein for the normal functioning of brain cells and other cells that secrete hormones to control various functions of the body, such as growth and reproduction. However, this protein can be modified by special enzymes: a small fragment called the peptide secretoneurin is important for stimulating sexual function. The peptide acts on brain cells and the pituitary gland to increase the release of hormones, thus enhancing the female’s ability to ovulate and lay her eggs.
” We have discovered new genes that can regulate reproduction , and the peptide secretoneurin is therefore a new hormone,” explains Trudeau.
The secretoneurin produced in fish is remarkably similar to that found in other animals, including humans. Scientists can now use these genetically modified fish to look for other factors that could improve sexual function , either to increase spawning in fish species or to aid in the search for new human infertility treatments.
“This is just the beginning of the possibilities. The large secregranin-2 genes can produce many other hormone-like peptides with unknown functions. It will be exciting to explore this in future research projects, ”he concludes.
The article “Directed mutation of Secretogranin-2 disrupts sexual behavior and reproduction in zebrafish” has been published in the scientific journal PNAS.
References:
Kimberly Mitchell el al., “Targeted mutation of secretgranin-2 disrupts sexual behavior and reproduction in zebrafish,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2002004117
