Social factors and aromatase gene expression during adult male-to-female sex change in captive leopard grouper Mycteroperca rosacea

Bidirectional sex-change behavior and physiological aspects in the Gorgeous goby Lythrypnus pulchellus (Gobiidae)

The Gorgeous goby Lythrypnus pulchellus shows extreme sexual plasticity with the bidirectional sex-change ability socially controlled in adults. Therefore, this study describes how the hierarchical status affects hormone synthesis through newborn hormone waste products in water and tests the influence of body size and social dominance establishment in sex reversal duration and direction. The associated changes in behavior and hormone levels are described under laboratory conditions in male-male and female-female pairs of similar and different body sizes, recording the changes until spawning. The status establishment occurred in a relatively shorter time period in male and female pairs of different sizes (1-3 days) compared to those of similar size (3-5 days), but the earlier one did not significantly affect the overall time of sex change (verified by pair spawning). The changes in gonads, hormones, and papilla occurred in sex-changer individuals, but the first one was observed in behavior. Courtship started at 3-5 days in male pairs and from 2 h to 1 day in female pairs of both groups of different and similar sizes. Hormones did not gradually move in the new sexual phenotype direction during the sex-change time course. Nonetheless, estradiol regulated sex change and 11-ketotestosterone enabled bidirectional sex change and was modulated by agonistic interactions. Cortisol is associated with status and gonadal sex change. In general, similar mechanisms underlie sex change in both directions with a temporal change sequence in phases. These results shed new light on sex-change mechanisms. Further studies should be performed to determine whether these localized changes exist in the steroid hormone synthesis along the brain-pituitary gonad axis during social and bidirectional sex changes in L. pulchellus.

Socially controlled male-to-female sex reversal in the protogynous orange-spotted grouper, Epinephelus coioides

Socially controlled sex change in teleosts is a dramatic example of adaptive reproductive plasticity. In many cases, the occurrence of sex change is triggered by a change in the social context, such as the disappearance of the dominant individual. The orange-spotted grouper Epinephelus coioides is a typical protogynous hermaphrodite fish that changes sex from female to male and remains male throughout its life span. In this study, male-to-female sex reversal in male Epinephelus coioides was successfully induced by social isolation. The body length and mass, gonadal change, serum sex steroid hormone levels and sex-related gene expression patterns during the process of socially controlled male-to-female sex reversal in E. coioides were systematically examined. This report investigates the physiological mechanisms of the socially controlled male-to-female sex reversal process in a protogynous hermaphrodite grouper species. The results enable us to study the physiological control of sex change, not only from female to male, but also from male to female.