• Development and Reproduction
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• v.16 no.4
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• pp.279-287
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• 2012

We investigated the changes in plasma sex steroid hormones, testosterone (T), estradiol-$17{\beta}$ ($E_2$), 17,$20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$), 11-ketotestosterone (11KT) and cortisol levels from ribbed gunnel, Dictyosoma burgeri in associated with annual reproductive cycle. The gonadosomatic index (GSI) of females increased from November, peaked in February and decreased rapidly from March. The GSI of males also increased from November, peaked in January and then decreased gradually. In females, $E_2$ levels increased and remained high from December to February. The levels of T showed a similar tendency and correlated ($r_s$=0.898, p<0.01) with $E_2$ levels. The levels of $17{\alpha}20{\beta}P$ increased rapidly in February ($4.78{\pm}1.01ng/ml$) and peaked in July ($5.08{\pm}0.65ng/ml$). Cortisol level was peaked in March and correlated with $17{\alpha}20{\beta}P$ levels ($r_s$=0.696, p<0.01). In males, the levels of T was peaked in January and then decreased rapidly. The levels of 11KT were remained high from October to January. On the other hand, the levels of $17{\alpha}20{\beta}P$ fluctuated during reproductive cycle. These results suggest that plasma sex steroids in ribbed gunnels have annual periodicity, and that cortisol may involve in maturation of females.

• Development and Reproduction
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• v.14 no.2
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• pp.115-121
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• 2010

The in vitro effects of nonylphenol (NP) and 2,2',4,6,6'-pentachlorobiphenyl (PCB104) on ovarian steroidogenesis of the ribbed gunnel, Dictyosoma burgeri were investigated. Oocytes taken during maturation stage were incubated with 100 ng/$m{\ell}$ of NP and PCB104 in the presence of exogenous precursor, $[^3H]-17{\alpha}$-hydroxyprogesterone ($[^3H]-17{\alpha}OHP$). Steroids were extracted from the media and the isolated oocytes, and the extracts were separated and identified by thin layer chromatography. The identities of the major metabolites were testosterone (T) and estradiol-$17{\beta}$ (E2). NP treatment inhibited production of E2 metabolite in the oocytes of 1.2, 1.3 and 1.4 mm although NP inhibited production of T metabolite at the oocytes of 1.1, 1.3 and 1.4 mm. PCB104 treatment inhibited production of T metabolite in the oocytes of all groups and E2 metabolite in the oocytes of 1.2, 1.3 and 1.4 mm. In conclusion, these results suggested that NP and PCB104 had an inhibitory effects on conversion of $[^3H]-17{\alpha}OHP$ to T and E2 during the oocyte maturation process of ribbed gunnel.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.8-15
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• 2007

The morphology of gonad and reproductive cycle of ribbed gunnel (Dictyosoma burgeri) were investigated on the basis of histological observation. The specimens were monthly sampled in the coastal waters of Jeju from November 2001 to February 2003. The ovaries and testis of this species are categorized as cystovarian and lobule type, respectively. The gonadosomatic index (GSI) of female increased in November and maintained high values from December to February. The GSI of male was similar to that of female although it was decreased in February. The reproductive cycle can be grouped into the following successive stage in the ovary: growth (October to November), mature (November to February), spawning (January to February), and degenerating and recovery (March to September). And in the testis, the stage observed were: multiplication (August to November), growth (November to January), mature and spawning (November to February), and degenerating and recovery (January to September). The minimum maturation size of D. burgeri was over 15.0 cm and fecundity ranged from 2,194 to 6,581 eggs. The relationship between the fecundity and fish body was calculated in the fecundity (F) equation as: $F=0.4057TL^{3.1425}$ ($R^2=0.7621$) for total length (TL); $F=149.88BW^{0.9579}$ ($R^2=0.7982$) for body weight (BW), respectively. The fecundity was correlated positively with TL and BW. The histological observations of the gonads suggested that major spawning of this species probably occurs between January to February, when low water temperature ($13{\pm}0.3^{\circ}C$) period.