• Development and Reproduction
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• v.15 no.3
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• pp.223-230
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• 2011

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants derived from incomplete combustion of carbons and crude oil. In this study, we investigated the effects of benzo[a]pyrene (B[a]P), a representative PAHs on in vitro sex steroid hormone production and germinal vesicle breakdown (GVBD) using isolated oocytes of longchin goby (Chasmichthys dolichognathus) and chameleon goby (Tridentiger trigonocephalus). Oocytes in diameters of 0.8-0.9 (end vitellogenic stage) and 0.9-1.0 mm (germinal vesicle migratory stage) from longchin goby and 0.5 mm (fully vitellogenic stage) from chameleon goby were used. In GVBD assay, B[a]P at 10 nM stimulated GVBD in the oocytes of 0.8-0.9 mm from longchin goby. B[a]P at 1 nM stimulated GVBD in the oocytes with diameter 0.5 mm from chameleon goby. In steroid production from oocytes of longchin goby, B[a]P at 100 nM decreased testosterone (T) production, B[a]P at 1,000 nM increased estraiol-17 (J (E2) production and 10 and 100 nM increased $17,20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$) production in the oocytes with diameter 0.8-0.9 mm. B[a]P at 1,000 nM increased E2 production, 100 and 1,000 nM increased $17{\alpha}20{\beta}P$ production in the oocytes with diameter 0.9-1.0 mm. In steroid production of oocytes from chameleon goby, B[a]P at 1,000 nM increased $E_2$ production. B[a]P at 10 nM increased $17{\alpha}20{\beta}P$ production. In the ratio of $E_2$ to T ($E_2$/T), B[a]P at 100 and 1,000 nM increased $E_2$/T in the oocytes of longchin goby. B[a]P at 100 nM also increased $E_2$/T in the oocytes of chameleon goby. Taken together, these results suggest that B[a]P have not only weak estrogenic effects but progestogenic effects on oocyte maturation.

• Development and Reproduction
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• v.27 no.3
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• pp.127-135
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• 2023

Effects of changes in photoperiod on the reproductive events in fish are suggested to be mediated mainly via the action of melatonin (MEL). Changing levels of plasma MEL throughout the day and year are suggested to influence the hypothalamus-pituitary-gonadal axis in fish. Therefore, in this study, we aimed to investigate the effects of MEL on oocyte maturation and germinal vesicle breakdown (GVBD) in the marine fish, Chaenogobius annularis, in vitro. Oocytes at three different stages (pre-, mid-, and late-vitellogenesis) were incubated with (a) only MEL (5, 10, 50, 100, 500, and 1,000 pg/mL) and (b) 50 pg/mL of 17α,20β-dihydroxy-4-pregnen-3-one (17α20βP), maturation-inducing hormone (MIH) of this species, and MEL (4-h incubation before addition of MIH). Any single MEL treatment did not significantly induce GVBD. However, treatment with 50 pg/mL MEL or MIH significantly induced GVBD. These results suggest that preincubation with MEL accelerates the effect of MIH on longchin goby oocyte maturation.

• Development and Reproduction
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• v.23 no.2
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• pp.111-117
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• 2019

This study focused on the association of prostaglandins and a progestin, $17{\alpha}$, $20{\beta}P$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$) during the ovulation process in longchin goby, Chasmichthys dolichognathus. We performed several in vitro experiments using $850-920{\mu}m$ diameter oocytes which were at the migratory nucleus stage. With the $890-920{\mu}m$ diameter oocytes, no significant difference in ovulation was observed in any of the prostaglandins (PGE1, PGE2, and $PGF2{\alpha}$) treated groups although PGE2 and $PGF2{\alpha}$ at concentrations of 50 ng/mL increased ovulation slightly compared with controls; however, $17{\alpha}20{\beta}P$ production was stimulated with PGE1 alone at low concentrations (5 ng/mL). In $850{\mu}m$ diameter oocytes, $PGF2{\alpha}$ at concentrations of 50 and 500 ng/mL resulted in a significant increase in ovulation. $17{\alpha}20{\beta}P$ (50 ng/mL) alone had no observable effect on ovulation, but in the combined of $PGF2{\alpha}$ 50 or 500 ng/mL it caused the greatest effect on ovulation. The sensitivity of oocytes to the induction of ovulation varies between 850 and $890-920{\mu}m$, it appeared to vary depending on the migration status of nucleus. These results suggest that $PGF2{\alpha}$ (or combined of $17{\alpha}20{\beta}P$) was more potent in inducing ovulation of the longchin goby.

• Development and Reproduction
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• v.12 no.1
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• pp.107-112
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• 2008

To investigate the $C_{21}$-steroids produced from maturating oocytes in the longchin goby, Chasmichthys dolichognathus, the oocytes ($0.74{\sim}0.97\;mm$) were incubated with radiolabeled $17{\alpha}$-hydroxyprogesterone ($^3H-17{\alpha}OHP$) for 24 hours. The resulting metabolites were analyzed by thin layer chromatography and identified by gas chromatography-mass spectrometry. Two $C_{21}$-steroids, $17{\alpha}$-hydroxy, $20{\alpha}$-dihydroprogesterone ($17{\alpha}20{\alpha}P$) and $17{\alpha}$-hydroxy, $20{\beta}$-dihydroprogesterone ($17{\alpha}20{\beta}P$), were converted from $^3H-17{\alpha}OHP$ in the maturing oocytes. These two main metabolites were detected at 0.80 mm diameter oocytes or greater. In addition, the effects of these metabolites on in vitro germinal vesicle breakdown (GVBD) were tested. The sensitivity of oocytes to the induction of GVBD was greater at $17{\alpha}20{\beta}P$ than $17{\alpha}20{\alpha}P$. This result showed that $17{\alpha}20{\beta}P$ is a major maturation inducing steroid (MIS) in longchin goby, suggesting $17{\alpha}20{\alpha}P$ may play a role in regulating the oocyte maturation process.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.477-483
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• 1985

This paper describes seasonal changes of total length, hepatosomatic index (HSI), fatness, egg-diameter composition, and fecundity of the longchin goby Chasmichthys dolichognathus(HILGENDORF). The specimens used were captured in the tide pool of Tongbaekseom, Pusan, Korea from February 1983 to January 1984. The age of longchin goby, tested by size frequency, was believed to be usually one year which grows to 8.0 cm in total length. The annual variations of HSI reached the maximum in the early spring when the gonad was actively growing and decreased during the spawning season from April to July. The coefficients of fatness were represented low values for the spawning periods. Frequency distribution of the egg diameter of mature ovary has three modes: one is the evident mode of the ripe eggs group, and the other two are modes of maturing and immature eggs groups. And an individual is considered as spawns one in the spawning season. Relationships between the fish size in total length (TL cm) and the number of ovarian eggs(F), the fish weight (BW g) and the number of ovarian eggs are indicated by the exponential equation respectively : F=42.585 $TL^{1.608}$, F= 524.589 $BW^{0.475}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.192-196
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• 2004

The in vitro effect of bisphenol A (BPA) on ovarian steroidogenesis of the longchin goby (Chasmichthys dolichognathus) was investigated. Oocytes taken during the maturing phase (vitellogenic, fully vitellogenic or germinal vesicle breakdown stage) were incubated with BPA (100 ng/mL) in the presence of exogenous precursor $^{3}H-17\alpha\;hydroxyprogesterone\;(^{3}H-17\alphaOHP).$ Steroids were extracted from the media and the isolated oocytes, and the extracts were separated and identified by thin layer chromatography and gas chromatography-mass spectrometry. The identities of the major metabolites were progestogens $[17{\alpha}-hydroxy,20{\alpha}-dihydroprogesterone\;(17{\alpha}20{\alpha}OHP)\;and\;17{\alpha}-hydrxy,20{\beta}-dihydroprogesterone\;(17{\alpha}20{\beta}OHP),$ androgens [androstenedione (A4) and testosterone (T)] and estrogens [estrone $(E_1)\;and\;estradiol-17{\beta}(E_2)].$ BPA treatment inhibited production of estrogens in all the maturing phases and progestogens in the germinal vesicle migrating stage. Percentage yield of estrogens was decreased with increased yield of androgens. In conclusion, BPA had an inhibitory effect on the conversion of $^3H-17\alphaOHP$ to estrogens and progestogens. These results demonstrate that BPA can act either estrogenic or anti-estrogenic effects.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.243-252
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• 1985

The mechanism of reproductive cycle of longchin goby Chasmichthys dolichognathus was investigated for the annual variations of gonadosomatic index(GSI), histological changes of gonad, reproductive cycle, and initiating and terminating factors of the breeding season. The experimental fish were captured in the tide pool of Tongbaeksom, Pusan, Korea from February 1983 to September 1984. Experimental fish for the study of initiating and terminating factors of the breeding season were maintained in filtered recirculating aquariums and exposed to various temperature and photoperiod regimes. The ovary is a pair of sac-shaped organ, and the testicular structure is tubular and it is connected to the seminal vesicle which is located at the posterior end of the testis. GSI began to increase from February when the water temperature began to increase and reached peak in April. It began to decrease from August, the top water temperature season, and maintained relatively low values until January. The annual reproductive cycle includes successive six developmental stages : early growing from December to February, late growing from January to March, early mature from February to May, late mature and ripe from March to August, spawning from April to July, degeneration and resting stage from May to December. An experimental study based on the reproductive cycle of this species indicated that rising temperature under long photoperiod during spring stimulated gonadal maturation, whereas terminating factor of the breeding season with recrudescence of the gonads was demonstrated as high water temperature during summer regardless of photoperiod.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.1
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• pp.41-47
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• 2017

Perhaps the most common type of reproductive dysfunction in captive fish is failure of females to undergo final oocyte maturation and thus to ovulate and spawn. The success of aquaculture could therefore be improved by developing techniques to enhance natural spawning, artificial maturation, and/or to induce ovulation in farmed fish. This study aimed to investigate the effects of prostaglandin $E_2$ ($PGE_2$) and prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) on in vitro oocyte maturation (germinal vesicle breakdown, GVBD) and ovulation in the marine fish Chasmichthys dolichognathus. Post-vitellogenic follicles (0.80-0.94 mm diameter oocytes) were incubated with $PGE_2$ or $PGF_{2{\alpha}}$ at concentrations of 5, 50, or 500 ng/mL for 24 hours. A significant increase in GVBD was seen in 0.84 mm and 0.94 mm oocytes incubated with 50 ng/mL $PGE_2$ compared with the control. There was no significant increase in GVBD in any of the other experimental conditions (5 or 500 ng/mL $PGE_2$ or 5, 50, or 500 ng/mL $PGF_{2{\alpha}}$). Neither of the prostaglandins induced ovulation at the concentrations tested.These results suggest that GVBD was induced by incubation with 50 ng/mL $PGE_2$.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.267-272
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• 2016

The feeding habits of Chaenogobius annularis were studied based on gut contents analysis of 315 individuals, collected from September 2014 to August 2015 in the tidepools at the intertidal zone of Tongyeong, Korea. The size of C. annularis ranged from 17.0 to 54.0 mm in standard length (SL). C. annularis mainly consumed copepods (especially Tigriopus japonicus). Its diets included seaweeds, cirripeds, mysids and amphipods. C. annularis showed ontogenetic changes in feeding habits. Small individuals fed mainly on copepods. As body size increased, the portion of seaweed increased, whereas the consumption of copepods decreased.