Changes in Plasma Steroid Hormone Levels and Gonad Development by the Control of Photoperiods and Water Temperatures on Timing of Sexual Maturity of Rockfish (Sebastes schlegeli)원문보기
Baek Hea-Ja
(Department of Marine Biology, Pukyong National University)
,
Park Moo-Eog
(Fisheries Resources Development Institute)
,
Lee Young-Don
(Marine and Environmental Research Institute, Cheju National University)
,
Kim Hyung-Bae
(Department of Marine Biotechnology, Kangwon Provincial University)
,
Rho Sum
(Marine and Environmental Research Institute, Cheju National University)
Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually d...
Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually decreased to 9L: 15D in October. It was then gradually increased to 12L:12D in January, followed by 14L:I0D in February. The water temperature was $19-20^{\circ}C$ in July. From August to October, it was from $18^{\circ}C\;to\;12^{\circ}C$. Then, it was dropped to a low of $19-11^{\circ}C$ in November to December and then gradually increased to $14-15^{\circ}C$ in February. In females, both plasma $estradiol-l7\beta\;$ (E2) and testosterone (T) levels from August to February showed a similar pattern in both the treatment and the control groups. In the treatment group, the peaks of plasma E2 and T were observed in November, and the peaks were closely correlated to histological observations. Oocytes contained many yolk globules (final vitellogenic oocytes), and oocytes at the migratory nucleus stage increased in size. Plasma levels of progesterone did not change much throughout the experimental period. However, in the control group, the peaks of E2, T, and progesterone were observed in February. These results indicate that the controlled photoperiod and water temperature accelerated sexual maturity, corresponding to the advancement of plasma E2 and T peaks by approximately 3 months. In males, plasma T levels showed a similar pattern from August to October in the treatment and control groups, though levels in the treatment group were higher than those in the control group. From histological observations, the treatment group copulated one month earlier.
Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually decreased to 9L: 15D in October. It was then gradually increased to 12L:12D in January, followed by 14L:I0D in February. The water temperature was $19-20^{\circ}C$ in July. From August to October, it was from $18^{\circ}C\;to\;12^{\circ}C$. Then, it was dropped to a low of $19-11^{\circ}C$ in November to December and then gradually increased to $14-15^{\circ}C$ in February. In females, both plasma $estradiol-l7\beta\;$ (E2) and testosterone (T) levels from August to February showed a similar pattern in both the treatment and the control groups. In the treatment group, the peaks of plasma E2 and T were observed in November, and the peaks were closely correlated to histological observations. Oocytes contained many yolk globules (final vitellogenic oocytes), and oocytes at the migratory nucleus stage increased in size. Plasma levels of progesterone did not change much throughout the experimental period. However, in the control group, the peaks of E2, T, and progesterone were observed in February. These results indicate that the controlled photoperiod and water temperature accelerated sexual maturity, corresponding to the advancement of plasma E2 and T peaks by approximately 3 months. In males, plasma T levels showed a similar pattern from August to October in the treatment and control groups, though levels in the treatment group were higher than those in the control group. From histological observations, the treatment group copulated one month earlier.
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제안 방법
But they did not present hormonal changes of the fish for the advanced maturation. This study meas니red plasma steroid changes together with gonadal histo logy, under the controlled photoperiod and tempera ture regimes on timing maturation. Plasma estradiol- 1 危 testosterone and progesterone levels were monitored in females, and plasma testosterone levels were monitored in males.
대상 데이터
3 mL/L), checked for signs of sexual maturation. Gonads and blood samples were taken from 10 individuals (5 females and 5 males) in each group. The blood samples were immediately centrifuged, and the plasma was stored at -20 °C until analysis for testosterone in both sexes, and estradiol in and progesterone for females.
데이터처리
Changes in plasma estradiol-17/?, testosterone and progesterone of the treatment and the control groups in female Sebastes schlegeli. Each value re presents the mean S.E. Significant differences (*p <0.05) between treatment and control were determined by Student's t~test.
Changes in plasma estradiol-17/?, testosterone and progesterone of the treatment and the control groups in female Sebastes schlegeli. Each value re presents the mean S.E. Significant differences (*p <0.05) between treatment and control were determined by Student's t~test.
후속연구
(2001) reported also the copulation in S, schlegeli could be advanced one montn by controlling photoperiod and tem perature. Further studies are needed to ascertain the involvement of steroids in the reproductive process other thar testosterone.
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