Females-fry Japanese madaki (Oryzias latipes) appear functional male sex organs, if they have five days did not eat, writing in Biology Open. Normally, the female body is formed of lipids is sufficient to suppress the development of testes, but fasting is not enough.
The Japanese Medak (still referred to as Japanese oizumi), as in humans, gender is determined by chromosomes. Below the body was a male, on the Y-chromosome in his cells should be a distinct area (theoretically it can also be located on the X chromosome, but this is rare). However, unlike us, these fish can change gender during life. The genes of such individuals will remain the same, but there are functional sexual organs, which the fish with such a set of chromosomes should not be.
In such cases, sex-change run change in environmental conditions. Medak females become males, if they have long elevated levels of the stress hormone cortisol. It may occur at a constant elevated temperature of the water. Another factor may be a lack of food. It is known that the lack of nutrients reduces the number of germ cells in females of laboratory mice, Drosophila , and even ctenophores. He probably could affect Medak.
Check how Oryzias latipes react to starvation, came from Japanese biologists headed by Minoru Tanaka (Minoru Tanaka) from Nagoya University. They suggested that lack of nutrients would interfere with lipid metabolism. Plays an important role Pantothenic acid — madaki the incapable to develop it yourself. Therefore, in addition to the fish fry, which is five days after leaving the egg completely deprived of food, there were several groups Medak, in which water was added Pantothenic acid in various concentrations, and the group that was administered the inhibitor of the metabolism of this acid (which is not allowed to form the desired lipids).
Based on available data on sex determination, the Japanese suggested that if sex change happens, it will be linked to the work of the gene dmrt1. Males Medak its expression in normal is higher than in females. And the fish, a mutant defective in this gene, there is a change sex: males become phenotypic females, that is, they have working ovaries. Therefore, fasting was subjected to not only the Medak wild type but also mutant for the gene dmrt1. Fish of all groups were determined by the content of lipids in the body with the dye Oil Red O, the phenotypic gender of the animals was identified by visual inspection of the genital area, dorsal and anal fins, the expression of dmrt1 — it QPCR RNA. Secondary phenotypic gender was determined in fish when they were 3-4 months. Looked on the genetic — the presence of a Y chromosome.