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Role of ecdysteroids in the molting and reproductive cycles of the white shrimp, Penaeus vannamei

Thesis/Dissertation ·
OSTI ID:6718018
The molt cycle was characterized in the white shrimp Penaeus vannamei based upon changes in the morphology of pleopod setae. These characters were used subsequently to determine changes in ecdysteroids and related biosynthetic events during the stages of the molting cycle and in relation to reproduction. Ecdysteroid titers were measured during the molting cycle. They increased during the premolt, decreased at ecdysis and remained minimal through the intermolt. 20-hydroxyecdysone (20-OHE) was the major ecdysteroid present during the premolt. Injection of ({sup 3}H)ecdysone resulted in label accumulation in the epidermis and hepatopancreas in the form of 20-OHE which was subsequently hydroxylated further to a polar metabolite. ({sup 3}H)ecdysone was not metabolized by the Y-organ, hemolymph, muscle or intestine. Eyestalk ablation elevated hemolymph ecdysteroid titers and reduced the duration of all molt stages. However, 20-OHE injection into intact animals caused a disproportionate reduction in the durations of only the intermolt and early premolt stages.
Research Organization:
Texas A and M Univ., College Station, TX (USA)
OSTI ID:
6718018
Country of Publication:
United States
Language:
English