• Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.12-19
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• 2022

In the present study, we investigated the effects of recombinant eel gonadotropins (rec-GTHs) on maturation induction in immature ovarian culture in vitro and sex steroid hormones in vivo in the Japanese eel Anguilla japonica. To study the in vitro effects of rec-GTHs on estradiol-17β (E2) production in immature ovarian tissues, ovarian tissues were incubated with different doses of rec-follicle-stimulating hormone (rec-FSH) or rec-luteinizing hormone (rec-LH). The results revealed that the E2 levels in the rec-FSH (0.1, 0.5, or 1 ㎍/mL)- and rec-LH (0.1 or 0.5 ㎍/mL)-treated groups were significantly higher than those in the female eels from the control group. Furthermore, to investigate the in vivo effects of rec-GTHs on the gonadosomatic index (GSI) and plasma sex steroid hormone levels, the eels were injected intraperitoneally with eel's ringer (control), salmon pituitary extract (SPE; for female eels), human chorionic gonadotropin (hCG; for male eels), rec-FSH, rec-LH, and rec-FSH + rec-LH once a week. The results revealed that except for the SPE and the hCG groups, none of the groups exhibited a significant difference in GSI values. However, in vivo plasma E2 levels increased at the end of 4 weeks after rec-FSH treatment in female eels. Based on these results, it is suggested that rec-GTHs may have a positive effect on sexual maturation in female eels; however, further studies on complementary rec-protein production systems and additional glycosylation of rec-hormones are needed to elucidate hormone bioactivity in vivo and in vitro.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.208-218
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• 2001

We have investigated the gonad index (GI), gonadal development, reproductive cycle, first sexual maturity, sex ratio, the number of spawned eggs and spawning frequency of the Manila clam, Ruditapes philippinarum. Samples were collected from the intertidal zone of Komso Bay, Korea from January to December in 1999. Monthly changes in the gonad index (GI) and condition index showed a similar pattern in the reproductive cycle. The spawning period was once a year between early June and early October, there was a spawning peak between July and August when seawater temperature was over $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (June to October), and spent/inactive stage (August to March). Percentages of first sexual maturity of female and male clams of l5.1-20.0mm in shell length were $56.3\%$ and $60.0\%$, respectively, and $100\%$ for the clams >25. mm. The sex ratio of individuals >15.1 mm in shell length was about 1:1 $(\chi^2= 0.02,\;p>0.05)$. Number of the eggs released from each clam by the induction increased as the size of clam in terms of shell length increased. Mean number of the eggs from the second induction of the spawning was $75.35-84.30\%$ $(average\;79.81\%)$ of the number of the eggs released in the first spawning. Our data indicated that R. philippinarum in Komso Bay has one major spawning peak with over two minor spawning, and the interval of each spawning was estimated to be approximately 15-17 (average 16.5) days.

• 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.

• Korean Journal of Psychosomatic Medicine
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• v.6 no.2
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• pp.97-103
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• 1998

A dolescence can be defined as the period between pubescence and physical maturity, and the passage through adolescence(age of 12-19) forms a critical period. Major developmental tasks of adolescence are construction of an emancipated identity, realistic ambitions, and reasonable ideals, and the further development of sexual and social identities. In early adolescence one struggles to adjust psychologically to the spurt in growth and tensions filled with sexual and aggressive impulses. There are reshuffling of peer groups due to differing rates of maturation, early adolescence crushes, sublimation of sexuality, and the resurgence of oedipal feelings. One reaches so-called period of formal operations in cognitive development. In mid-adolescence one struggles to overcome family attachments and controls, and it is a time marked by revolt and conformity. One has to overcome sexual repression while caught in reactivation of oedipal attachment. Peer groups gains in importance, and the peer group changes into a youth group that carries the youth culture. Late adolescence is a period of achieving an ego identity and capacities for intimacy. One has to prevent premature closure : Identity foreclosure limits both opportunity and the ability to guide one's own life. Gradually adolescent begins to have a loss self-centered and narcissistic orientation to one's sexual and affectional needs, and becomes involved in love relationship.

• Korean Journal of Environmental Biology
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• v.33 no.2
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• pp.248-255
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• 2015

Induction of regeneration and maturation of the free-living gametophytes of Saccharina japonica was studied at four temperatures (5, 10, 15 and $20^{\circ}C$), four levels of irradiance (5, 10, 20 and $40{\mu}mol\;m^{-2}\;s^{-1}$) and three photoperiods (14 : 10, 12 : 12 and 10 : 14 h L : D). Female gametophyte fragments were maintained in active regeneration without reaching sexual maturity under conditions of $15^{\circ}C$, $20{\mu}mol\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D), whereas the conditions for male gametophytes were slightly different at $15^{\circ}C$, $5{\mu}mol\;m^{-2}\;s^{-1}$, 14 : 10 h (L : D). The sexual maturation of female and male gametophytes took place under $5^{\circ}C$, $20{\sim}40{\mu}mol\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D) and $15^{\circ}C$, $40{\mu}mol\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D), respectively. These results provide basic information for controlling the regenerationand maturation of free-living gametophytes for strain improvement and cross breeding of S. japonica.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.622-630
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• 2017

The induction of regeneration and the maturation of the free-living gametophytes of Undaria pinnatifida were studied at temperatures(5, 10, 15 and $20^{\circ}C$), irradiance (5, 10, 20 and $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$) and photoperiods (14 : 10, 12 : 12 and 10 : 14 h L: D). Female gametophyte fragments were maintained in active regeneration without them reaching sexual maturity under conditions of $15^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D); by contrast, the conditions for male gametophytes were slightly different at $15^{\circ}C$, $5{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14 : 10 h (L: D). The sexual maturation of female and male gametophytes took place under $5^{\circ}C$, $20-40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D) and $15^{\circ}C$, $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10 : 14 h (L : D), respectively. These results provide basic information for controlling the regeneration and maturation of free-living gametophytes for srain improvement as well as the cross breeding of U. pinnatifida.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.576-583
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• 2018

Investigation of optimal temperature, irradiance and photoperiod conditions for free-living gametophytes of Saccharina sculpera for natural resources conservation and mass cultivation of endangered species in the eastern coast of Korea. Induction of regeneration and maturation of the free-living gametophytes of S. sculpera were cultured at temperatures (5, 10, 15, 20 and $25^{\circ}C$), irradiance (10, 20, 40, 60 and $80{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and photoperiods (14:10, 12:12 and 10:14 h L:D). The female gametophyte were actively regenerated without reaching sexual maturity under $10^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and 12:12 h (L:D) conditions. In contrast, the conditions for male gametophytes were slightly different at $15^{\circ}C$, $10{\mu}mol\;photons\;m^{-2}\;s^{-1}$ and 12:12 h (L:D). The sexual maturation of female and male gametophytes took place under $15^{\circ}C$, $40{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 14:10 h (L:D) and $10^{\circ}C$, $20{\mu}mol\;photons\;m^{-2}\;s^{-1}$, 10:14 h (L:D), respectively. These results provide basic information for controlling the regeneration and maturation of free-living gametophytes for conservation and utilization of S. sculpera.

• The Plant Pathology Journal
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• v.30 no.3
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• pp.236-244
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• 2014

The plant pathogen Fusarium graminearum causes Fusarium head blight in cereal crops and produces mycotoxins that are harmful to animals and humans. For the initiation and spread of disease, asexual and sexual reproduction is required. Therefore, studies on fungal reproduction contribute to the development of new methods to control and maintain the fungal population. Screening a previously generated transcription factor mutant collection, we identified one putative $C_2H_2$ zincfinger transcription factor, pcs1, which is required for both sexual and asexual reproduction. Deleting pcs1 in F. graminearum resulted in a dramatic reduction in conidial production and a complete loss of sexual reproduction. The pathways and gene ontology of pcs1-dependent genes from microarray experiments showed that several G-protein related pathways, oxidase activity, ribosome biogenesis, and RNA binding and processing were highly enriched, suggesting that pcs1 is involved in several different biological processes. Further, overexpression of pcs1 increased conidial production and resulted in earlier maturation of ascospores compared to the wild-type strain. Additionally, the vegetative growth of the overexpression mutants was decreased in nutrient-rich conditions but was not different from the wild-type strain in nutrient-poor conditions. Overall, we discovered that the pcs1 transcription factor positively regulates both conidiation and sexual reproduction and confers nutrient condition-dependent vegetative growth.

• Mycobiology
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• v.49 no.3
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• pp.258-266
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• 2021

The velvet regulators VosA and VelB are primarily involved in spore maturation and dormancy. Previous studies found that the VosA-VelB hetero-complex coordinates certain target genes that are related to fungal differentiation and conidial maturation in Aspergillus nidulans. Here, we characterized the VosA/VelB-inhibited developmental gene vidD in A. nidulans. Phenotypic analyses demonstrated that the vidD deleted mutant exhibited defect fungal growth, a reduced number of conidia, and delayed formation of sexual fruiting bodies. The deletion of vidD decreased the amount of conidial trehalose, increased the sensitivity against heat stress, and reduced the conidial viability. Moreover, the absence of vidD resulted in increased production of sterigmatocystin. Together, these results show that VidD is required for proper fungal growth, development, and sterigmatocystin production in A. nidulans.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.369-374
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• 2009

The stumpy bullhead (Pseudobagrus brevicorpus) endemic to Korea is one of critically endangered freshwater fish species. To provide baseline data for its captive breeding and reintroduction we investigated basal characteristics on its growth and sexual maturation in an artificial rearing environment. After 698-day rearing the stumpy bullhead grew up to $89.22{\pm}10.29\;mm$ in total length (TL) and $70.93{\pm}7.68\;g$ in total body weight (BW)($BW=5\times10^{-5}\;TL^{2.678}$; $R^2=0.995$), and showed survival rate of 74.2%. The sex ratio was 1 (471 females) : 1 (473 males), and males ($TL=87.44{\pm}1.07mm$; $BW=8.43{\pm}0.31\;g$) showed significantly faster growth than females ($TL=78.38{\pm}0.92mm$; $BW=6.38{\pm}0.20\;g$) after 663-day rearing. However, condition factor of females was significantly higher than that of males (P<0.05). The number of eggs per female ranged from 508 to 867 (average 734), and their diameters ranged from 0.04 to 1.65 mm. The females which reared about two years in the laboratory condition was able to spawn in the early June after 1~2 days of human chorionic gonadotropin (HCG) injection. The number of hatched fries ranged from 113 to 338 (average 216).