Regular ArticleSex Change and Steroid Profiles in the Protandrous Anemonefish Amphiprion melanopus (Pomacentridae, Teleostei)
Abstract
Plasma profiles of several gonadal steroids and cortisol were examined in a field population of the protandrous, sex-changing anemonefish Amphiprion melanopus to elucidate potential roles of these hormones in gonadal sex change. Sex change was experimentally induced in males by removal of their dominant female pair mates. These sex-changing males were captured and sampled at 5, 10, or 20 days after female removal. Unmanipulated males and females were also sampled. Males had higher plasma levels of II-ketotestosterone (II-KT) than did females, but had lower levels of androstenedione (Ad), testosterone (T), and estradiol-17β (E2). The three androgens showed decreases from male levels at 10 days, then an increasing trend at 20 days after female removal. E2 levels exhibited no changes from male levels until 20 days, when a significant increase over male levels was observed. Mature females had higher levels of Ad, T, and E2 than the 20-day treatment group, indicating that these steroids continue to rise after Day 20. The results support hypothesized roles for androgens in male function and E2 in female function in A. melanopus. However, E2 increases lagged behind oogonial proliferation, arguing against an influence of this steroid in the initiation of female function. Cortisol levels did not differ between males and females, but exhibited an increase during sex change, peaking at 20 days.
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Sex differences in aggressive intensities and brain steroids during status resolution in a sex changing fish, Lythrypnus dalli
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New cells added to the preoptic area during sex change in the common clownfish Amphiprion ocellaris
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Stable and persistent male-like behavior during male-to-female sex change in the common clownfish Amphiprion ocellaris
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Sexual plasticity in bony fishes: Analyzing morphological to molecular changes of sex reversal
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Impact of bisphenol-A and synthetic estradiol on brain, behavior, gonads and sex hormones in a sexually labile coral reef fish
2021, Hormones and BehaviorEndocrine disrupting chemicals, such as bisphenol A (BPA) and ethinylestradiol (EE2), are detected in the marine environment from plastic waste and wastewater effluent. However, their impact on reproduction in sexually labile coral reef fish is unknown. The objective of this study was to determine impacts of environmentally relevant concentrations of BPA and EE2 on behavior, brain gene expression, gonadal histology, sex hormone profile, and plasma vitellogenin (Vtg) levels in the anemonefish, Amphiprion ocellaris. A. ocellaris display post-maturational sex change from male to female in nature. Sexually immature, male fish were paired together and fed twice daily with normal food (control), food containing BPA (100 μg/kg), or EE2 (0.02 μg/kg) (n = 9 pairs/group). Aggression toward an intruder male was measured at 1, 3, and 6 months. Blood was collected at 3 and 6 months to measure estradiol (E2), 11-ketotestosterone (11-KT), and Vtg. At the end of the study, fish were euthanized to assess gonad morphology and to measure expression of known sexually dimorphic genes in the brain. Relative to control, BPA decreased aggression, altered brain transcript levels, increased non-vitellogenic and vitellogenic eggs in the gonad, reduced 11-KT, and increased plasma Vtg. In two BPA-treated pairs, both individuals had vitellogenic eggs, which does not naturally occur. EE2 reduced 11-KT in subordinate individuals and altered expression of one transcript in the brain toward the female profile. Results suggest BPA, and to a lesser extent EE2, pollution in coral reef ecosystems could interfere with normal reproductive physiology and behavior of the iconic sexually labile anemonefish.