Hypogonadotropic hypogonadism in male tilapia lacking a functional rln3b gene.
Qinglei Xu, Maolin Ye, Yun Su, Li Feng, Linyan Zhou, Jian Xu, Deshou Wang
Author Information
Qinglei Xu: Fisheries Engineering Institute, Chinese Academy of Fishery Sciences, Beijing 100141, China.
Maolin Ye: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China.
Yun Su: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China.
Li Feng: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China.
Linyan Zhou: Fisheries Engineering Institute, Chinese Academy of Fishery Sciences, Beijing 100141, China. Electronic address: zhly@cafs.ac.cn.
Jian Xu: Fisheries Engineering Institute, Chinese Academy of Fishery Sciences, Beijing 100141, China. Electronic address: xuj@cafs.ac.cn.
Deshou Wang: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing 400715, China. Electronic address: wdeshou@swu.edu.cn.
Relaxin 3 is a neuropeptide that plays a crucial role in reproductive functions of mammals. Previous studies have confirmed that rln3a plays an important role in the male reproduction of tilapia. To further understand the significance of its paralogous gene rln3b in male fertility, we generated a homozygous mutant line of rln3b in Nile tilapia. Our findings indicated that rln3b mutation delayed spermatogenesis and led to abnormal testes structure. Knocking out rln3b gene resulted in a decrease in sperm count, sperm motility and male fish fertility. TUNEL detection revealed a small amount of apoptosis in the testes of rln3b male fish at 390 days after hatching (dah). RT-qPCR analysis demonstrated that mutation of rln3b gene caused a significant downregulation of steroid synthesis-related genes such as cyp17a1, cyp11b2, germ cell marker gene, Vasa, and gonadal somatic cell marker genes of amh and amhr2. Furthermore, we found a significant down-regulation of hypothalamic-pituitary-gonadal (HPG) axis-related genes, while a significantly up-regulation of the dopamine synthetase gene in the rln3b male fish. Taken together, our data strongly suggested that Rln3b played a crucial role in the fertility of XY tilapia by regulating HPG axis genes.
