ANALYSIS OF THE MASCULINIZING STRENGTH OF SINGLE AND DOUBLE COPIES OF THE TESTIS-DETERMINING FACTOR AMHY IN PEJERREY ODONTESTHES BONARIENSIS

Hayakawa S., Yamamoto Y., Hattori RS, Strüssmann C.A.

Tokyo University of Marine Science and Technology, Tokyo, Japan

yoji@m.kaiyodai.ac.jp

The pejerrey Odontesthes bonariensis is recognized as temperature-dependent sex determined and yet possess a genetic testis-determining factor (amhy; Y chromosome-linked anti-Müllerian hormone gene) which is primarily functional at mid-range temperatures (hence, genotypic sex determination). However, still little is known on how amhy initiates the testis formation cascade and its interactions with other sex differentiation genes. Moreover, we have recently demonstrated that individuals with a double Y complement (YY; hence two copies of amhy) are viable and fertile in pejerrey and can be found in natural habitats, but the masculinizing strength of single and double copies of amhy at different temperatures has never been tested. Such knowledge is crucial to understand the evolution of sex determination mechanisms in fishes and to accurately predict the effects of global warming and climate change on their populations. In this study we mated a XY (sex-reversed) female to a XY male and reared the offspring genetically consisting of 1XX: 2XY : 1YY at feminizing, intermediate, and masculinizing temperatures to examine the contribution of one or two single copies to gender determination. Here we shown that, as hypothesized, the presence of double copies of amhy conferred increased likelihood of becoming a male compared to a single copy not only at intermediate to high temperatures, but also at a low, otherwise feminizing temperature. We also discuss the relations of amhy gene expression to other major sex differentiation genes such as amha (the autosomal form of amh) and cyp19a1a (gonadal aromatase). The results of this study provide important considerations for the management of pejerrey resources in view of the current trend of global warming/climate change and predicted increase in phenotypic/genotypic sex mismatches in natural populations.

Palabras clave: TSD, SEX DETERMINATION, AMHY, SUPERMALES