ABSTRACT. The gonad-inhibiting hormone (GIH) belongs to a neuropeptide family synthesized and released in an X-organ sinus gland complex of crustacean eyestalks. GIH inhibits crustacean ovarian maturation by suppressing vitellogenin (Vtg) synthesis, whereas estrogen is responsible for the stimulation of vitellogenesis (not established). In this study, the effects of 17β-estradiol (E 2 , 10 -6 M), estrogen receptor antagonist tamoxifen (TAM, 10 -6 , 10 -7 , and 10 -8 M), and the environmental estrogen nonylphenol (NP, 1 μg/L and 100 μg/L) on LvGIH expression in the eyestalks of shrimp were determined by quantitative real-time PCR. Results showed that LvGIH expression decreased significantly during the L. vannamei ovarian maturation cycle. E 2 and NP significantly reduced LvGIH transcripts in 14057 GIH expression with estrogen treatment in L. vannamei ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 14056-14065 (2015) vivo, but TAM neutralized the inhibitory action of E 2 in a dose-dependent manner (P < 0.05). In addition, the LvGIH expression levels decreased significantly in a time-dependent manner (P < 0.05) when ovary fragments were cultured in vitro with E 2 . The results of this study suggested that estrogen regulates GIH expression in L. vannamei eyestalks. E 2 promoted ovarian development not only by directly upregulating vitellogenesis in the hepatopancreas, but it was also capable of downregulating LvGIH expression, which indirectly resulted in the stimulation of L. vannamei vitellogenesis.

ABSTRACT. Androgen plays critical roles in vertebrate reproductive systems via androgen receptors (ARs). In the present study, the full-length spotted scat (Scatophagus argus) androgen receptor (sAR) cDNA sequence was cloned from testis. The sAR cDNA measured 2448 bp in length with an open-reading frame of 2289 bp, encoding 763 amino acids. Amino acid alignment analyses showed that the sARs exhibited highly evolutionary conserved functional domains. Phylogenetically, the sARs clustered within the ARβ common vertebrate group. Real-time polymerase chain reaction (RT-PCR) revealed that sAR expression varied in level and distribution throughout the tissues of both females and males. sAR expression was detected during testicular development by quantitative RT-PCR. The results showed that the highest transcription of sARs was observed in the mid-testicular stage, and remained at a high expression level until the latetesticular stage. In addition, the effects of 17α-methyltestosterone (MT) and estrogen (E 2 ) on the expression of sARs in ovaries were determined using quantitative RT-PCR. sAR expression increased at 12 and 24 h post- MT treatment and decreased with E 2 treatment. The present study provides preliminary evidence indicating gonadal plasticity of spotted scat under exogenous steroidal hormone treatments. It also provides a theoretical basis for sex reversal and production of artificial pseudo-males for female monosex breeding.