Prostaglandin E2 involvement in the reproduction of small abalone,Haliotis diversicolor

Prostaglandin E2(PGE2)has been reported to be involved in reproduction as one of the most abundant and widely distributed prostaglandins in invertebrates.Regulating gonad development and gamete production in mollusks can greatly assist artificial breeding,which is believed to promote the commercial benefits of various mollusk species.In the present study,the contents of PGE2 in the gonads of abalone at different developmental stages(maturing stage,ripe stage,and spawning stage)and reproduction states(before and after spawning)were measured.A higher PGE2 level was found in the gonads of abalones at the ripe stage than other stages,and the highest PGE2 level was detected in the ovaries of female H.diversicolor in the UV-stimulated group.Then the effects of PGE2 injection on the spawning efficiency were explored,and the gamete emission rates of female and male abalone were significantly increased after PGE2 injection.Through qRT-PCR and in situ hybridization assay,higher expression levels and wide distribution of phospholipase A2(PLA2),cyclooxygenase 2(COX2),prostaglandin E synthases(PGES2),and prostaglandin E2 receptor 4(EP4)in the gonads of H.diversicolor were observed after spawning.It is speculated that PGE2 may promote the reproductive cycle in both male and female H.diversicolor,although the regulation mechanism of PGE2 in female and male abalone might be different.The results will be useful for the application of PGE2 in the abalone aquaculture practices to increase the reproduction efficiency in future.