Ovarian and hemolymph ecdysteroid titers during vitellogenesis in Macrobrachium rosenbergii.

Changes in ovarian and hemolymph ecdysteroid concentration and composition during vitellogenesis have been investigated in the freshwater prawn Macrobrachium rosenbergii. Free ecdysteroids (20-hydroxyecdysone and ecdysone) in hemolymph increased in concentration during vitellogenesis from zero at stage 0 to 1.5 ng/ml at stage I to 7.3 ng/ml in mature, stage IV animals. 20-Hydroxyecdysonoic acid (1.2 ng/ml) was detected in the stage IV hemolymph. Ovarian-free ecdysteroid concentration, expressed as nanograms per gram of tissue, fell during vitellogenesis from 83.2 ng/g at stage 0, non-pigmented tissue to 14.2 ng/g at stage IV tissue, being minimal at stage I (6.3 ng/g). However, expression of ovarian free ecdysteroid content as nanograms per ovary revealed a rise from 7.7 ng/ovary at stage 0, nonpigmented tissue to 28.3 ng/ovary at stage IV, again being minimal at stage I (2.0 ng/ovary). 20-Hydroxyecdysonoic acid and ecdysonoic acid were identified at ovarian stages II-III and stage IV.