Tide-related Changes in mRNA Abundance of Aromatases and Estrogen Receptors in the Ovary and Brain of the Threespot Wrasse Halichoeres trimaculatus
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The threespot wrasse (Halichoeres trimaculatus; Family Labridae) is a common coral reef species of the Indo-Pacific Ocean. Given that this species spawns daily at high tide (HT), we hypothesized that endocrine changes in relation to gonadal development are synchronized with the tidal cycle. To test this, we examined the transcript abundance of two cytochrome P450 aromatases (cyp19a and cyp19b) and two estrogen receptors (erα and erβ) in the ovary and brain of this species in response to tidal change. When fish were collected around four tidal points [low tide (LT), flood tide (FT), high tide (HT), and ebb tide (ET)], gonadosomatic index and oocyte diameter increased around HT and FT, respectively. Ovulatory follicles were observed in ovaries around HT. Real-time quantitative polymerase-chain reaction revealed that mRNA abundance of cyp19a and erα, but not erβ, in the ovary increased around ET and HT, respectively. On the other hand, mRNA levels of cyp19b in the forebrain were significantly higher around FT. Increases of erα and erβ mRNA abundance around FT were observed in all areas of the brain and the midbrain, respectively. The changes in mRNA abundance of key genes involved in reproduction at specific tidal cycles, along with the development of the vitellogenic oocytes in the ovary, support our hypothesis that synchronization of endocrine changes to the tidal periodicity plays a role in the gonadal development of this species. We hypothesize that conversion of testosterone to E2 in the brain may be associated with the spawning behavior given that the wrasse exhibits group spawning with a territory-holding male around HT.
Keywordsaromatase brain estrogen receptor ovary tide wrasse
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- Chang XT, Kobayashi T, Kajiura H, Nakamura M, Nagahama Y (1997) Isolation and characterization of the cDNA encoding the tilapia (Oreochromis niloticus) cytochrome P450 aromatase (P450arom): changes in P450arom mRNA, protein, and enzyme activity in ovarian follicles during oogenesis. J Mol Endocrinol 18:57–66CrossRefGoogle Scholar
- Chaube R, Rawat A, Joy KP (2015) Molecular cloning and characterization of brain and ovarian cytochrome P450 aromatase genes in the catfish Heteropneustes fossilis: sex, tissue and seasonal variation in, and effects of gonadotropin on gene expression. Gen Comp Endocr 221:120–133CrossRefGoogle Scholar
- Chen H, Zhang Y, Li S, Lin M, Shi Y, Sang Q, Liu M, Zhang H, Lu D, Meng Z, Liu X, Lin H (2011) Molecular cloning, characterization and expression profiles of three estrogen receptors in protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides). Gen Comp Endocr 172:371–381CrossRefGoogle Scholar
- Hojo Y, Hattori TA, Enami T, Furukawa A, Suzuki K, Ishii HT, Mukai H, Morrison JH, Janssen WG, Kominami S, Harada N, Kimoto T, Kawato S (2003) Adult male rat hippocampus synthesizes estradiol from pregnenolone by cytochromes P45017? and P450 aromatase localized in neurons. P Natl Acad Sci USA 101:865–870CrossRefGoogle Scholar
- Nagahama Y (1994) Endocrine regulation of gametogenesis in fish. Int J Dev Biol 38:217–229Google Scholar
- Takemura A, Shibata Y, Takeuchi Y, Hur SP, Sugama N, Badruzzaman M (2012) Effects of hydrostatic pressure on monoaminergic activity in the brain of a tropical wrasse, Halicoeres trimaculatus: possible implication for controlling tidal-related reproductive activity. Gen Comp Endocr 175:173–179CrossRefGoogle Scholar