Effects of
bilateral eyestalk ablation on molting and ovarian development in the giant
freshwater prawn, Macrobrachium rosenbergii
T. Okumura, K. Aida-2001
Fisheries Science, 67(6) : 1125-1135
Abstract :
In the present study, the effects of
bilateral eyestalk ablation on molt interval, ovarian development, and
hemolymph levels of ecdysteroid and vitellogenin were investigated in the
giant freshwater prawn, Macrobrachium rosenbergii in order to examine
the roles of the eyestalk hormones. In destalked males and females,
ecdysteroid levels increased rapidly, and molt intervals were significantly
shortened in comparison with control non-destalked prawns. All destalked
females exhibited a reproductive molt cycle accompanied by ovarian
development and oviposition even under continuous hemolymph sampling. In
contrast, in control females, the percentages of animals undergoing a
reproductive molt cycle were 69 and 51% with and without sampling,
respectively. The duration of ovarian development was shortened in the
destalked females. These results indicate the inhibitory roles of the
eyestalk hormones on molting and vitellogenesis. On the other hand, after
eyestalk ablation, male prawns molted more than twice, and destalked females
showed a correlation of vitellogenin level to molt stage similar to control
reproductive females. These results indicate that the molt cycle and the
correlation between vitellogenesis and molting are maintained in the absence
of eyestalk hormone regulation.
(Department of Aquatic Bioscience, Graduate School of
Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo
113-8657, Japan)