Embryonic ecdysteroids in a mole crab, Emerita asiatica (Milne-Edwards)

Using radioimmunoassay (RIA) and high performance liquid chromatography (HP LC), the presence of a complex mixture of free and conjugated ecdysteroids is reported in the embryonated eggs of a mole crab, Emerita asiatica. From an initial low value of 6.5 ng/g egg wet weight in stage I, the total ecdys teroids increased in concentration to 15.2 ng/g egg wet weight in stage III . This was followed by a sharp fail in stage IV, but again increased to 15. 0 ng/g egg wet weight in stage VI. After a further decline in stage VII, th e total ecdysteroids registered the highest value of 36.2 ng/g egg wet weig ht in stage VIII. This value, however, declined to a low level in the preha tching stage (IX). The concentration of the free ecdysteroids always predom inated over the conjugated ones. The HPLC analysis of free ecdysteroids dem onstrated the presence of 20-hydroxyecdysone and ecdysone in the ratio of 2 .5. Purified lipovitellin II also contained free and conjugated ecdysteroid s. The functional significance of the embryonic ecdysteroids as well as the ir nature of synthesis and storage within the eggs is discussed in the ligh t of the information available on insect embryogenesis.