A research group led by Assistant Professor Ryuhei Kiminami of Kinki University has demonstrated for the first time in the world the existence of super female (WW) sturgeon with only the W chromosome, using a newly developed PCR test method.It is hoped that this will lead to the establishment of technology for hatching only females to be used as caviar.
Sturgeons have a 1:1 ratio of females to males, and the males and females cannot be distinguished by appearance.For this reason, for several years until the gonads develop, males that cannot produce caviar will continue to be bred, and the poor production efficiency in aquaculture has become a major issue.
The sex-determining chromosomes of sturgeons are represented by Z and W, and there are males (ZZ) with only Z chromosomes and females (ZW) with Z and W chromosomes.It has been reported that males emerge through a technique called gynogenesis, in which individuals with only maternally-derived chromosomes are generated.On the other hand, although it has been suggested that superfemales with only the W chromosome exist among sturgeon born by gynogenesis, the existence of such females has not been proven.
Based on the whole genome information of sterlet, the research group developed a PCR test method that simultaneously detects DNA sequences specific to both males and females.Of the 112 sturgeon juveniles produced by gynogenesis, 21 were male (ZZ), 66 were female (ZW), and 25 were superfemales with WW chromosomes.When a super-female (WW) and a male (ZZ) mate, the offspring will all be female.
In this way, if it is possible to select extra-female (WW) from sturgeon born through gynogenesis, raise them to parent fish, and collect eggs, it will be possible to produce all females, and the efficiency of caviar production by farmed sturgeon will be dramatically improved. It is said that it will be.
