Detection and mode of action of retinoids on ovarian development in the mud crab, Scylla serrata

In the current study, the retinoic acid isomers such as 9-cis retinoic acid and all-trans retinoic acid were detected in the mature ovaries of mud crabs, Scylla serrata using HPLC analysis. Given the detection of retinoids in the ovaries, an attempt has been made to elucidate the possible role of retinoic acid in the regulation of reproduction in mud crabs. Injection of 9-cis retinoic acid induced ovarian maturation in intact mud crabs as evidenced by a significance elevation in the ovarian index (226.76%; P 0.001), and oocyte diameter (150.61%; P 0.001) accompanied by accumulation of yolk globules in the oocytes as compared to the untreated crabs. Further, a significant increase (258.63%; P 0.0001) in the circulatory ecdysteroid levels were also observed in 9-cis retinoic acid injected mud crabs over vehicle injected crabs. From the results, it can be postulated that retinoic acid-induced stimulation of ovarian maturation at least in part mediates ecdysteroids in the mud crabs.