Thompson, M.J., Insect Physiology Laboratory, Agricultural Research Service, USDA Beltsville, MD 20705, United States
Svoboda, J.A., Insect Physiology Laboratory, Agricultural Research Service, USDA Beltsville, MD 20705, United States
Weirich, G.F., Insect Physiology Laboratory, Agricultural Research Service, USDA Beltsville, MD 20705, United States
Svoboda, J.A., Insect Physiology Laboratory, Agricultural Research Service, USDA Beltsville, MD 20705, United States
Weirich, G.F., Insect Physiology Laboratory, Agricultural Research Service, USDA Beltsville, MD 20705, United States
Ecdysteroids of ovaries and newly-laid eggs (0- to 1-hour-old) of the tobacco hornworm are present mainly as conjugates (>95%). Newly-laid eggs contain ecdysteroid conjugates equivalent to 21 μg of 26-hydroxyecdysone and 0.73 μg of ecdysone per gram of eggs. These levels are similar in ovaries of 93-hour-old adult females. In 1- to 18-hour-old eggs more than 63% of the ecdysteroids exist in the free form and the proportion is similar in 48- to 64-hour-old eggs. The ratio of 26-hydroxyecdysone to ecdysone in the conjugated form remains constant during oocyte maturation and embryogenesis. Though 26-hydroxyecdysone is without molting hormone activity in the house fly assay, the exceptionally high concentration of 26-hydroxyecdysone conjugate(s) in ovaries and newly-laid eggs, together with the fact that it is being released during embryogenesis, indicate some physiological role for 26-hydroxyecdysone. © 1984.
