Japanese scientists were able to identify and alter a gene in a species of fish’s reproductive system that can determine what a germ cell would turn out to be during the reproductive process – an egg or a sperm.
Germ cells are precursor cells in the reproductive system that generates gametes in animals that sexually reproduce. Gametes are called eggs in females and sperm cells in males.
Researchers published a paper about their experiments on a tiny fish named the medaka, or the Japanese rice fish, in this Thursday’s issue of the journal Science. They said that the gene which is responsible for the genetic switch between egg and sperm in germ cells was dubbed foxl3.
Though germ cells are common to most vertebrates and are found in both males and females, scientists were clueless about the mechanism that triggered germ cells’ later development within the animals’ reproductive system.
No other study had found that there was a gene that controlled whether germ cells would become male reproductive cells or female reproductive cells.
During their experiments, researchers had to perform a series of tests to determine foxl3’s role. The elusive gene is mostly active in female germ cells, where its role is to prevent those cells from morphing into sperm cells in female ovaries.
The gene was dormant in other types of cells found in the medaka’s reproductive system.
When the team turned the gene off in female fish, they learned that germs cells became sperm cells in the ovaries instead of egg cells as it was natural to do in females. The resulting sperm cells were able to fertilize other egg cells and resulted in a healthy new generation.
Although, humans do not have a foxl3 to control their reproduction, scientists speculate that a similar genetic mechanism may determine the future of their germ cells, as well.
Minoru Tanaka, co-author of the study and lead researcher at the National Institute for Basic Biology in Okazaki, Japan, said that scientific community didn’t know about germ cells’ genetic switch to determine their fate.
“The germ cells were regarded as passive cells that are regulated by other cells,”
expalined Mr. Tanaka.
Mr. Tanaka’s fellow researcher Toshiya Nishimura said he was “greatly surprised” when he witnessed what the gene could do to germ cells. He added that the surprise nearly turned into a shock when realizing that the cells of the environment in which germ cells were altered into male reproductive cells were female cells.
Image Source: suisin.jimu.kyushu-u.ac.jp