Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Ocean Science Journal 53 (2018): 239-249, doi:10.1007/s12601-018-0016-0.
Description:
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 (er and er) 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 er, but not er, 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 er and er 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.
Description:
This study was supported partially by the 21st Century COE program “The Comprehensive
Analyses on Biodiversity in Coral Reef and Island Ecosystems in Asian and Pacific Regions”
from the Ministry of Education, Culture, Sports, Science and Technology, Japan, JSPS
KAKENHI Grant number 16H05796, and the Natural Sciences and Engineering Research
Council (NSERC, Canada) Discovery Grant program.
Keywords:
Aromatase
;
Brain
;
Estrogen receptor
;
Ovary
;
Tide
;
Wrasse
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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