Metabolism of ecdysteroid by testes of the tobacco budworm,Heliothis virescens

Testes from late last stage larvae of the tobacco budworm, Heliothis virescens, were incubated with ³H]ecdysone and ³H]cholesterol. ³H]Ecdysone was converted to six other major ecdysteroids, identified by cochromatography in reverse-phase high-pressure liquid chromatography (RPHPLC); four of them were verified by normal-phase HPLC. A highly polar fraction, moderately polar ecdysteroids (20,26-dihydroxyecdysone, 3-epi-20-hydroxyecdysone, and 20-hydroxyecdysone) and low-polarity ecdysteroids, including 2-deoxyecdysone, were detected after incubation with ³H]ecdysone. Compounds that reacted positively to antibodies to progesterone and testosterone were detected in the low-polarity fractions. Testes were incubated in fractions corresponding to each of the major ecdysteroid peaks derived from ³H]ecdysone metabolism. Although most of the radioactive ecdysteroid fractions were further metabolized to high- and low-polarity endpoints, 88% of the ³H]20-hydroxyecdysone peak apparently remained unmetabolized. 20-Hydroxyecdysone may be the primary ecdysteroid product of testes of H. virescens. ³H]Cholesterol was not metabolized to any appreciable extent.