Abstract
Radioimmunoassay (RIA) was applied to identify selected metabolites obtained in in vitro incubations of ovarian and hepatopancreatic tissues from female Marsupenaeus japonicus in previtellogenic and vitellogenic maturation stages. Depending on the precursors used, progesterone, 17?-hydroxyprogesterone or testosterone, it was possible to observe the presence of several enzymatic activities through metabolites detected in incubations. The present study provides evidence that the ovary of the shrimp M. japonicus is capable of synthesising 17?-estradiol from progesterone, evidencing the presence of 17?-hydroxylase, C 17 -C 20 lyase, 17?-hydroxysteroid dehydrogenase (17?-HSD) and aromatase. Enzymatic activities of aromatase, 3?-HSD and 17?-hydroxylase were detected in hepatopancreas, but not that of C 17 -C 20 lyase. These results suggest that 17?-estradiol could be the vitellogenesis stimulating ovarian hormone (VSOH), and together with former in vivo and in vitro studies this leads us to propose that in fact there may be a physiological role for steroid hormones in the maturation cycle of crustaceans.
Highlights
Of ovary maturation, is a major problem for the development of crustacean culture, since several species do not mature without external manipulation
To be fully elucidated, this process is known to be controlled by hormonal factors that can be either neuroendocrine or other, such as steroid hormones (Van Herp and Payen, 1991)
The concentrations of 17α-hydroxyprogesterone, testosterone and 17β-estradiol obtained in the incubations of the ovarian tissue in the presence or absence of a steroid hormone precursor
Summary
Of ovary maturation, is a major problem for the development of crustacean culture, since several species do not mature without external manipulation. To be fully elucidated, this process is known to be controlled by hormonal factors that can be either neuroendocrine or other, such as steroid hormones (Van Herp and Payen, 1991). The in vivo stimulation of vitellogenesis in marine penaeid prawns by progesterone (Kulkarni et al, 1979; Van Herp and Payen, 1991). In fresh water species by progesterone (Sarajoni et al, 1985) or by estrone and 17β-estradiol (Sarajoni et al, 1986) was reported. 17αhydroxyprogesterone was demonstrated to stimulate vitellogenesis in marine penaeids (Nagabhushanam et al, 1980; Yano, 1987) and to increase oocyte diameter in Litopenaeus vannamei (Tsukimura and Kamemoto, 1988). Other researchers reported lack of response to either 17α-hydroxyprogesterone or 17β-estradiol as vitellogenin stimulating hormones in Penaeus esculentus (Koskela et al, 1992)
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