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
(from Current Contents)
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.
(Japan Sea Natl Fisheries Res Inst, Fisheries Res Agcy, 1-5939-22 Suido
Cho, Niigata 9518121, Japan, e-mail: takuji@affrc.go.jp)