HEMOLYMPH VITELLOGENIN LEVELS AND OVARIAN DEVELOPMENT DURING THE REPRODUCTIVE AND NON- REPRODUCTIVE MOLT CYCLES IN THE GIANT FRESHWATER PRAWN MACROBRACHIUM ROSENBERGII
T. Okumura, K. Aida-2000
Fisheries Science, 66 (4) : 678-685 (from Current Contents)
Abstract:
In this study, ovarian development and vitellogenin levels were determined during the reproductive and non-reproductive molt cycles in the giant freshwater prawn Macrobrachium rosenbergii in order to examine the relationship between vitellogenesis and molting. During the reproductive molt cycle, the ovary developed synchronously with the advancement of molting stage. At molting stages B-C-0, the ovaries contained oogonia and oocytes at the previtellogenic and endogenous vitellogenic stages, and hemolymph vitellogenin levels were relatively low (2.4-3.0 mg/mL). At stage C-1, yolk accumulation commenced in oocytes at the endogenous vitellogenic stage, after which oocytes entered the exogenous vitellogenic stage. Vitellogenin levels increased (4.9 mg/mL) at this stage. During premolt stages D-0-D-3, vitellogenin titers were high (4.7-7.3 mg/mL), and gonadosomatic index (GSI) increased rapidly due to the yolk accumulation in the oocytes. Following ecdysis, yolk accumulation was completed at stage A(0), and oviposition occurred. Entering stage A, vitellogenin levels became low (0.6-1.3 mg/mL). In contrast, throughout the non-reproductive molt cycle, GSI remained low, and oocytes did not develop beyond the previtellogenic or endogenous vitellogenic stage. Some atretic oocytes at the exogenous vitellogenic stage were observed in a few females. During the nonreproductive molt cycle, vitellogenin levels did not show distinct changes in relation to the molt cycle.
(Japan Sea Natl Fisheries Res Inst, Niigata 9518121, Japan, E-mail : takuji@affrc.go.jp)
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