Induction of vitellogenesis, methyl farnesoate synthesis and ecdysteroidogenesis in two edible crabs by arachidonic acid and prostaglandins

The present study investigated the effect of arachidonic acid (AA) and selected prostaglandins on the regulation of vitellogenesis, ecdysteroidogenesis and methyl farnesoate (MF) synthesis in the freshwater crab Oziotelphusa senex senex and the giant mud crab, Scylla serrata. Administration of AA and prostaglandin F-2 alpha (PGF(2 alpha)) and prostaglandin E-2 (PGE(2)) significantly increased ovarian index, oocyte diameter and ovarian vitellogenin levels and ecdysteroid andMF levels in the hemolymph of crabs. Secretions of MF and ecdysteroids from in vitro cultured mandibular organs (MO) and Y-organs (YO) isolated from intermolt crabs injected with AA, PG(2 alpha) and PGE(2) were greater when compared with controls. In contrast, injection of prostaglandin D-2 (PGD(2)) had no effect on vitellogenesis, ecdysteroid and MF levels in circulation. In vitro secretion of MF from MO explants isolated from avitellogenic crabs incubated with AA, PGF(2 alpha) and PGE(2) increased in a time-dependent manner. Conversely, incubation of YOs isolated from avitellogenic crabs with AA, PGF(2 alpha) and PGE(2) had no effect on secretion of ecdsyteroids. These results implicate prostaglandins in the regulation of reproduction by inducing the synthesis of MF and consequent ecdysteroid synthesis in brachyuran crabs, and provide an alternativemolecular interventionmechanismto the traditional eyestalk ablation methodology to induce vitellogenesis and ovarian maturation in crustaceans.