High temperature-induced sterility in the female Nile tilapia, Oreochromis niloticus.
High temperature treatments induce germ cell loss in gonads of vertebrate animals, including fish. It could be a reliable source for induction of sterility if the treatments led to a permanent loss of germ cells. Here we report that heat treatment at 37 °C for 45-60 days caused a complete loss of germ cells in female Nile tilapia, Oreochromis niloticus, and that sterility was achieved in fish at all stages of their life cycle. Unlike previous observations, germ cells did not repopulate even after returning them to the water at control conditions suggesting permanent depletion of germ cells. Gonadal somatic cells immunopositive for 3β-hydroxysteroid dehydrogenase (3β-HSD) were clustered at one end of the germ cell depleted gonads close to the blood vessel. Serum level of testosterone, 11-ketotestosterone, and 17β-estradiol was significantly decreased in sterile fish compared to control. Body weight of sterile fish was higher than control fish at the end of experiment. Our observations of increased growth and permanent sterilization in the high temperature-treated fish suggest that this method could be an appropriate and eco-friendly tool for inducing sterility in fish with a higher thermal tolerance.
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko 3422, Motobu, Okinawa 905-0227, Japan; Tribhuvan University, Institute of Agriculture and Animal Science (IAAS), Paklihawa Campus, Rupendehi, Nepal.
Narayan Prasad
NP
Pandit
School of Biological Sciences, University of Missouri, Columbia, MO 65211, USA. Electronic address: bhandarir@missouri.edu.
Ramji Kumar
RK
Bhandari
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko 3422, Motobu, Okinawa 905-0227, Japan.
Yasuhisa
Y
Kobayashi
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko 3422, Motobu, Okinawa 905-0227, Japan; Okinawa Churashima Foundation, 888 Ishikawa, Motobu-cho, Kunigami-gun, Okinawa 905-0206, Japan. Electronic address: m-nakamura@okichura.jp.
Masaru
M
Nakamura
D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000818:Animals; D023681:Cichlids / Q000378:metabolism; D004958:Estradiol / Q000097:blood; D005260:Female; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism*; D006358:Hot Temperature / Q000009:adverse effects*; D007246:Infertility / Q000209:etiology* / Q000378:metabolism; D008018:Life Cycle Stages / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood
D013739:Testosterone; D004958:Estradiol; D015067:17-Hydroxysteroid Dehydrogenases; C044256:3 (or 17)-beta-hydroxysteroid dehydrogenase; C003600:11-ketotestosterone
Germ cells; High temperature; Nile tilapia; Sterility