A joint research group of the Graduate School of Science, the University of Tokyo and the National Institute of Genetics has found that the evolution of the male-specific gene "OTOKOGI" produces males by decoding the entire genome of the "green algae Volvox series", which is a model organism for sexual evolution. It suggested that it may have been the cause.
Multicellular organisms such as humans are divided into males that produce small gametes (sperm) and females that produce large gametes (eggs).On the other hand, in primitive unicellular organisms, males and females are in an undifferentiated state due to the sex called "isomorphic gametes" in which the size of gametes is the same.Therefore, males and females have been thought to have evolved from "homologous" ancestral organisms, but it has been unclear what kind of gene group acquisition brings about male-female characteristics.
This time, the group focused on Yamagi Sierra, a "same-type gamete," and Eudorina, a "male-female gamete," which corresponds to the intermediate stage of evolution, among the "green algae Volvox series," which is a group of sex evolution model organisms. Genome decoding was performed to clarify the entire sex chromosome region of the corresponding organisms immediately before and after the birth of males and females.As a result, at the beginning of the emergence and evolution of males and females, this region of the sex chromosome does not expand, and the sex-specific gene "OTOKOGI" that exists in the tiny chromosome region "OSU" that the first males thought had. It was suggested that the evolution of function was the cause of the birth of the first male.In the future, comparative studies of downstream genes of this gene are expected.
Paper information:[Communications Biology] Anisogamy evolved with a reduced sex-determining region in volvocine green algae
