• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.3
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• pp.153-159
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• 2007

We studied oocyte steroidogenesis in relation to oocyte development in the greenling, Hexagrammos otakii, a marine multiple spawner. Vitellogenic and mature oocytes were incubated in vitro in the presence or absence of $[^3H]-17\;{\alpha}-hydroxyprogesterone$ as a precursor. The major metabolites were androgens [androstenedione $(A)_4)$ and testosterone (T)] and estrogens [$17\;{\beta}-estradiol\;(E_2)$ and estrone ($E_1$)] in vitellogenic oocytes. The metabolic rate of T was lower in 1.08 to 12-mm oocytes, while that of $E_2$ increased with oocyte size. The endogenous productions of T, $E_2$ and 17 ${\alpha}-hydroxy$, 20 ${\beta}-dihydroprogesterone\;(17{\alpha}20{\beta}OHP)$ were quantified using a radioimmunoassay in the non-precursor group. The endogenous levels of T and $E_2$ were highest in 1.08 to 12-mm oocytes and $17{\alpha}20{\beta}OHP$ was produced only in 1.90 to 95-mm oocytes. The relationship between oocyte size and steroidogenesis showed that 1.08 to 12-mm oocytes are full vitellogenic following induction of the maturation process. Moreover, $17{\alpha}20{\beta}OHP$ acts as a maturation inducing hormone in H. otakii.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.5
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• pp.391-397
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• 2006

This study correlated changes in estradiol-l7$\beta$ ($E_2$), testosterone (T), 17$\alpha$,20-dihydroxy-4-pregnen-3-one (DHP), and vitellogenin (VTG) levels with changes in the gonadosomatic index (GSI) and ovarian histology during the annual reproductive cycle of the wild marbled sole, Limanda yokohamae. Synchronous oocyte development occurs in this fish. Ovary maturity was classified into four periods, based on histological observations: the spawning (December to February), post-spawning (February to April), recovery (May to August), and vitellogenic (September to November) periods. Seasonal changes in the GSI were inversely correlated with water temperatures and reflected the degree of ovarian maturity. Plasma VTG levels were correlated with changes in the GSI, which increased from September to a peak in January, and levels remained comparatively high until February. Estradiol-17$\beta$ was at baseline levels (<0.11 ng/mL) during the spring and summer, and peaked rapidly (1.55$\pm$0.445 ng/mL) from October to January. Plasma T and DHP levels had a similar profile; they rose markedly during the spawning period and remained low (or were not detectable) from spring through autumn. These data indicate that changes in plsama steroid hormones and VTG levels are correlated with the annual ovarian activity of the marbled sole. Based on these results and published reports, it appears that in this species DHP is the most important maturation-inducing steroid and that T is also related to final maturation.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.1003-1012
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• 2012

The gonadosomatic index (GSI), sex steroid hormones and gonadal development of roughscale sole Clidoderma asperrimum cultured in indoor tank were investigated to evaluate its sexual maturation and reproductive cycle. The highest GSI values of female and male were $6.91{\pm}4.03$ (May) and $0.16{\pm}0.08$ (August), respectively. The reproductive cycle would be classified into four successive developmental stages: growing stage (December to February), maturation stage (March to April), ripe and spawning stage (May to June), recovery and resting stage (July to November). The highest plasma testosterone (T) and estradiol-$17{\beta}$ ($E_2$) levels of female were $259.4{\pm}76.8$ and $633.3{\pm}182.5$ pg/mL, respectively in May. Also $17{\alpha}$, $20{\beta}$-dihydroxy-4-pregen-3-one ($17{\alpha}$, $20{\beta}$-OHP) levels of female peaked in April before spawning season ($244.2{\pm}42.5$ pg/mL). The highest plasma testosterone (T) and 11-ketotestosterone levels of male were $231.0{\pm}46.0$ and $273.9{\pm}54.5$ pg/mL, respectively in April. But there was no significant difference in $17{\alpha}$, $20{\beta}$-OHP.

• Development and Reproduction
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• v.16 no.1
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• pp.39-45
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• 2012

To verify the sex steroids which are involved in oocyte maturation of the blacktip grouper, $Epinephelus$ $fasciatus$, we incubated vitellogenic oocytes (0.41 and 0.50 mm in average diameter) in the presence of exogenous steroid precursor ($[^3H]17{\alpha}$-hydroxyprogesterone). Steroids were extracted, separated and identified by thin layer chromatography. The major metabolites produced were androstenedione, estradiol-$17{\beta}$, estrone and progestogens. Progestogen metabolites in the oocytes of 0.50 mm were more abundant than those of 0.41 mm. Also, we investigated the $in$ $vitro$ effects of human chorionic gonadotropin (HCG; 5, 50 and 500 $IU/m{\ell}$), $17{\alpha},20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$) and $17{\alpha},20{\beta}$-trihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}21P$; 5, 50 and 500 $ng/m{\ell}$, respectively) on oocyte maturation. In the oocytes of 0.41 mm, treatment with 50 IU HCG stimulated GVBD ($55.30{\pm}1.20%$) compared with controls ($32.41{\pm}3.13%$, $p$<0.05). In the oocytes of 0.50 mm, treatment of $17{\alpha}20{\beta}P$ (50 and 500 $ng/m{\ell}$) stimulated GVBD ($50.13{\pm}2.52$ and $51.77{\pm}5.91%$, respectively) compared with controls ($36.81{\pm}2.89%$, $p$<0.05). Treatment with 500 IU HCG also stimulated GVBD ($49.59{\pm}5.15%$) compared with controls ($p$<0.05). Taken together, these results suggested that both HCG and $17{\alpha}20{\beta}P$ were effective on in vitro oocyte maturation and $17{\alpha}20{\beta}P$ may act as a maturation inducing hormone in blacktip grouper.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.57-64
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• 2010

The purpose of this investigation was to study the relationship between vertical facial pattern and dental maturation in children in pubertal and pre-pubertal periods. The material consisted of lateral head films and panoramic radiographs of 1306 patients. The subjects were selected according to Ricketts's VERT index and other including criteria. These subjects were divided by VERT index to brachyfacial group and dolichofacial group. In each selected subject, dental age was determined according to Demirjian's dental maturity score. All subjects were distributed according to age, vertical facial type and sex, mean and standard deviation of chronological age, dental age and age difference were determined in each group. And the data were analysed to find the difference of tooth maturation by facial pattern. Findings of this study include: 1. In all groups, dental age was determined higher than chronological age in statistically significant level. 2. Compared by vertical facial pattern, in pubertal age groups, it seems that subjects with brachyfacial type presented the tendency to have an advanced dental maturation, only in female group. 3. Compared by pubertal period, brachyfacial groups presented more advanced dental maturation in pubertal groups than pre-pubertal groups.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.105-112
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• 2009

We investigated the degree of obesity, histological development stages of gonads and sexual maturation induction rates of comb pen shell, Atrina pectinata, per the type of micro-algae supplied. Terms of maturation by singular or mixed supply of microalgae, it was found that maturation of the female was the quickest at 60.0% by the Tetraselmis tetrathele (Tet). experiment group followed by 57.1% by the Chlorella ellipsoidea (Chl). experiment group and 16.7% by the Phaeodactylum tricornutum (Pha). experiment group. However, there were no significant differences between Tet. experiment group and Chl. experiment group. As for the male, maturation was the quickest at 60.0% by the Tet. experiment group followed by 16.7% by the Chl. experiment group and 14.3% by the Pha. experiment group. In light of these results, Tet. is concluded to be a very useful feed organism in breeding the mother comb pen shells. Upon completion of the experiment, the sexual maturation induction rate for the female was found to be the highest at 82.0% in the Tet. experiment group followed by 72.0% by the Chl. experiment group, 64.0% by the Pha. experiment group and 58.0% by the mixed micro-algae experiment group. During the period of experiment, the survival rate was the highest at 94.4% by the mixed micro-algae experiment group followed by 90.0% by the Pha. experiment group, 83.1% by the Tet. experiment group and 78.8% by the Chl. experiment group.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.9-17
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• 2003

The gonad index (GI), reproductive cycle with gonad developmental phases, first sexual maturity and the sex ratio of the jedo venus, Protothaca jedensis, on the coastal waters of Boryeong, Korea were investigated by histological study. Samples were collected from the subtidal zone of Boryeong, Korea from January to December, 1999. Monthly changes in the gonad index in femal and male clams gradually increased from February and reached the maximum in May, and then the values rapidly decreased from June and reached the minimum in November as seen in variations of the reproductive cycle. The spawning period of this species was once a year between May and July, there was a spawning peak between June and July when seawater temperature was over 20$^{\circ}C$. The reproductive cycle of this species in female and male clams can be classified into five successive stages: early active stage (December to March), late active stage (February to June), ripe stage (April to July), partially spawned stage (May to July) and spent/inactive stage (July to January). Percentages of first sexual maturity of female and male clams of 30.1-35.0 mm in shell length were 52.6% and 60.0%, respectively, and 100% for the clams over 45.1 mm in shell length. The sex ratio of individuals > 30.1 mm in shell length was 1:1 (X$^2$ = 0.40, p > 0.05).

• Journal of Animal Science and Technology
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• v.48 no.5
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• pp.651-662
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• 2006

Phthalate esters that are used as plasticizers and also found at low levels in foods such as dairy products are often mentioned as suspected endocrine disrupters. The purpose of the present study is to elucidate whether perinatal exposure to di-n-butyl phthalate(DBP), diisononyl phthalate (DINP) and di-2-ethylhexyl adipate (DEHA) affects several aspects of reproductive function in rats especially sexual differentiation of the brain. To this end, the dams were provided with pulverized soy-free diet containing 20, 200, 2,000 and 10,000 ppm of DBP, 40, 400, 4,000 and 20,000 ppm of DINP, or 480, 2,400 and 12,000 ppm of DEHA from gestational day (GD) 15 to postnatal day (PDN) 21, the day of weaning, and serum sex steroid hormone, gonadotropin levels and sexual behaviors after maturation were assessed. At Postnatal week (PNW) 20-21, serum levels of sex steroids and gonadotropins in both male and female rats, as well as estrous cyclicity in females, were not changed by perinatal exposure to DBP, DINP and DEHA, indicating that these chemicals did not affect sexual differentiation of the brain controlling the endocrine system of hypothalamo-pituitary-gonadal (HPG) axis. On the other hand, inhibitory influences on sexual behaviors, especially on ejaculation in males and lordosis in females, were observed by perinatal exposure to these chemicals. These results suggest that these chemicals may act directly on discrete regions of the hypothalamus regulating sexual behaviors, but not regulating gonadotropin secretion, thereby affect sexual differentiation of the brain with a resultant decrease in sex-specific behaviors in adulthood.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.479-487
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• 2014

Leptin plays an important role in energy homeostasis and reproductive function in fish, especially in reproduction. Migrating fish, such as salmonoids, are affected by external environmental factors, and salinity changes are a particularly important influence on spawning migrations. The aim of this study was to test whether changes in salinity affect the expression of leptin, estrogen receptors (ERs), and vitellogenin (VTG) in chum salmon (Oncorhynchus keta). The expression and activity of leptin, the expression of ERs and VTG, and the levels of estradiol-$17{\beta}$ and cortisol increased after the fish were transferred to FW, demonstrating that changes in salinity stimulate the HPG axis in migrating female chum salmon. These findings reveal details about the role of elevated leptin levels and sex steroid hormones in stimulating sexual maturation and reproduction in response to salinity changes in chum salmon.

• 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.