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Komei HOTTA Takayuki WATANABE Chiho KISHIDA Yukio NAKAMURA Nobuyuki OHKUBO Takahiro MATSUBARA Shinji ADACHI Kohei YAMAUCHI 《Fisheries Science》2003,69(3):555-562
ABSTRACT: Because blood vitellogenin (Vg) has been considered a biomarker for environmental estrogens, the basal levels of Vg and 17β-estradiol (E2 ) were determined in male Japanese whiting reared under natural conditions. Serum levels of Vg and E2 were measured and gonadal development was assessed by gonadosomatic index (GSI) and histological observation in 8–10 male fish at monthly intervals throughout the annual reproductive cycle. Serum E2 was <60 pg/mL throughout the study period. In contrast, serum Vg exhibited seasonal changes: serum levels of Vg gradually increased from April to May (mean 63 ± 13 ng/mL and 124 ± 48 ng/mL in April and May, respectively), and then reached a peak value (mean 352 ± 68 ng/mL) in June. Thereafter, serum Vg gradually decreased, reaching undetectable levels (<50 ng/mL) in October. Serum levels of Vg tended to increase in the male fish in which the GSI was >1%. Histological observation revealed that testes in such male fish were in active spermatogenesis and then all of the testes of male fish in which serum Vg decreased to ND levels were regressed. These results suggest that Vg productive potency (sensitivity to estrogens) may increase in the spermatogenic stage, resulting in production of Vg in response to very low levels of natural or xenobiotic estrogens. 相似文献
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Youichi Hayakawa Hidekazu Nagaya Hiroki Kaki Komei Hotta Makito Kobayashi 《Fisheries Science》2009,75(1):137-144
We previously demonstrated the biological activities of single-chain recombinant gonadotropins (scGTHs) of goldfish Carrassius auratus follicle-stimulating hormone (scFSH) and luteinizing hormone (scLH), produced by a baculovirus–silkworm larvae system, by
using in vivo bioassays with some fishes including Japanese eel Anguilla japonica. Among the bioassays, we succeeded in induction of spermatogenesis of sexually immature male Japanese eels by both scFSH
and scLH, especially resulting in the occurrence of spermatozoa in scLH-administered males. However, those recombinant hormones
did not induce enlargement of testes. In order to further confirm the potency of recombinant GTHs for use in aquaculture species,
we administered scFSH and scLH to males of Japanese eel at higher dosage and frequency (eight times with 2–5 days interval)
than those of the previous study (five or six times with 7 days intervals), including combination of scFSH and scLH administration
(scFSH–scLH). Gonadosomatic indices (GSI) of scLH- and scFSH–scLH-administered males were larger than those of initial control
males and of control males that were injected with saline. Enlargement of testes was also confirmed by measurement of testicular
lobe size in scFSH-, scLH-, and scFSH–scLH-administered males. By histological observation, occurrence of spermatozoa was
confirmed in scLH- and scFSH–scLH-administered eels. Although milt production was not induced, higher dosage and frequency
of scGTH administration was effective in promoting testicular development of immature eels. Thus, single-chain fish GTHs produced
by the baculovirus–silkworm larvae system could be a useful tool for promotion of gonadal maturation in aquaculture fishes. 相似文献
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