Daily spawning and development of sensitivity to gonadotropin and maturation-inducing steroid in the oocytes of the bambooleaf wrasse, Pseudolabrus japonicus

Steroidogenic pathways to 17,20beta-dihydroxy-4-pregnen-3-one and 17,20beta,21-trihydroxy-4-pregnen-3-one in the ovarian follicles of the bambooleaf wrasse Pseudolabrus sieboldi

“…Therefore, we use the term bambooleaf wrasse to indicate P . sieboldi in the present study, which is consistent with previous studies we have done 12,13 …”

“…The bambooleaf wrasse Pseudolabrus japonicus is a diandric protogynous labrid fish 11 . The female spawns almost every day during the 2‐month spawning period, and has a diurnal rhythm in oocyte growth, maturation, ovulation, and spawning 12 . These features make this fish a good model for studying the endocrine control of oogenesis and ovulation.…”

Light Synchronization of the Daily Spawning Rhythms of Gilthead Sea bream (Sparus aurataL) Kept under Different Photoperiod and after Shifting the LD Cycle

“…A Japanese team (Kobayashi et al, 1988) studied the in vitro response of oocytes to different concentrations of steroids and gonadotropins at different times of the day in the kisu (Sillago japonica). The results indicate a daily rhythm in oocyte development similar to that observed in the bambooleaf Pseudolabrus japonicus (Matsuyama et al, 1998), further supporting the idea that fish, in general, possess a daily rhythm of gonadal maturation.…”

“…Indeed, if a fish shows very different behavioral diurnal, nocturnal, or crepuscular patterns (Madrid et al, 2001), it is reasonable to propose it will also select the right moment of the day to spawn to ensure maximum survival of offspring. In fact, daily changes in oocyte maturity and secretion of sexual steroids and gonadotropins have been described in species such as the red seabream (Pagrus major; Matsuyama et al, 1998), snapper (Pagrus auratus; Carragher & Pankhurst, 2003), kisu (Sillago japonica; Kobayashi et al, 1988), and European sea bass (Dicentrarchus labrax; Bayarri et al, 2004). Collectively, the evidence points to the existence of daily rhythmicity in fish reproduction.…”

Fecundity of banded wrasse(Notolabrus fucicola)from Otago, Southern New Zealand

“…Possible explanations are that hCG is not, or poorly, recognised by the wrasse ovary, akin to the situation in amago salmon (Oncorhynchus rhodurus; Young et al 1983). However, in vitro sensitivity to hCG in other wrasse species, such as the bambooleaf wrasse, Pseudolabrus japonicus (Matsuyama et al 1998) and Pacific wrasse, Haliochoeres trimaculatus (Leatherland et al 2003), suggests this is an unlikely explanation. Similarly, it is possible that 17a,20P-P is not the MIH, although this is unlikely in light of the findings on other wrasse (e.g., Matsuyama et al 2002).…”