• Development and Reproduction
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• v.19 no.4
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• pp.209-215
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• 2015

Red spotted grouper, Epinephelus akaara is a popular aquaculture species in many Asian countries. This species is a protogynous hermaphrodite that first differentiates into female and changes to male later. Due to this reproductive characteristic, stable supply of male and female gametes is a key to the success of seed production in this species. Thus, understanding early gonadal differentiation is required to develop effective sex control techniques. Red spotted grouper were reared in indoor tanks and sampled every 5 days from 40 days post-hatch (DPH) to 130 DPH. Changes of gonadal tissues were examined and analyzed by means of histology. A pair of gonadal primordium has already existed underneath the kidney in the posterior part of the body cavity at 38 DPH when this study began. Gonadal primordia of 38, 40 DPH consisted of germ cells surrounded by a few somatic cells. The blood vessel was observed in the gonadal primordium at 45 DPH. The number of somatic cells and size of gonadal primordium increased age-dependently up to 60 DPH. Formation of ovarian cavity was obvious by two protuberant aggregations of somatic cells at 65 DPH. Completed ovarian cavity and oogonia were first observed in the gonad of one fish sample at 105 DPH. Based on these histological observations, it can be suggested that induction of primary male differentiation could be more successfully applied at around 60 DPH in this species.

• Development and Reproduction
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• v.10 no.2
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• pp.79-84
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• 2006

We reviewed sex-change patterns in the wrasses Halichoeres poecilopterus, H. tenuispinis, Pteragogus flagellifer, and Pseudolabrus sieboldi inhabiting the coastal waters of Jeju, Korea, based on the sex distribution according to standard length and sex characteristics of the gonads. Halichoeres poecilopterus, H. tenuispinis, Pt. flagellifer, and Ps. sieboldi are protogynous hermaphroditic fish. Histological observations revealed that these wrasses are undelimited type 2 species because testicular tissue(spermatogenesis area) appears in most parts of the gonads during ovary of degenerative stage. Both initial- and terminal-phase males were present in the investigated populations, indicating that Halichoeres poecilopterus, H. tenuispinis, and Ps. sieboldi are of the diandric type. In contrast, Pt. flagellifer is considered a monandric type, because all males in the investigated populations were terminal-phase males produced via sex change from functional females.

• Development and Reproduction
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• v.20 no.4
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• pp.367-377
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• 2016

Red spotted grouper, Epinephelus akaara, is a popular aquaculture species and a protogynous hermaphrodite. Induction of artificial sex change at the time of primary sex differentiation is of interest but has not been successful due to the lack of necessary basic information. To find out the potential neuroendocrine influence on the primary sex differentiation, the expression of key genes in the brain was investigated during the formation of ovarian cavity. Expression of cyp19a1b, esr1, gnrhr1, fsh, lh and cga in the brain was positively associated with the formation of ovarian cavity, showing gradual increase as the formation proceeds. However, the expression of gnrh1 was suppressed during the early part of the ovarian cavity formation, signifying potential hypothalamic influence on the primary sex differentiation in this species.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.64-64
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• 2003

The sex differentiation of fishes occurs under the control of genetic and various environmental factors. DM-domain containing genes are novel zinc finger transcription factors and play key roles in sex determination. In order to isolate the wrasse DMRT (wDMRT) cDNA from the protogynous wrasse (Halichoeres tenuispinnis), the wrasse testis cDNA library was screened using the $^{32}$ P-labeled PCR products, which were amplified with the degenerate primers from conserved DM-domain regions of several DMRT genes. Among a few positives obtained through screening, the full length wDMRT cDNA of 2.9kb size encoding a predicted 300 amino acid residues was isolated. The sequence analysis exhibited 60%, 43% sequence identity with rainbow trout and tilapia DMRT1, respectively. RT-PCR assay showed that wDMRT was expressed specifically in male testis. Also, wDMRT gene was strongly expressed in May during reproductive season, when the reproductivity of wrasse is most active. This results suggested that wDMRT gene function in testis differentiation The conserved DM-domain regions were amplified using PCR from DMRT genes of several species among Labridae, and their sequences were determined. The sequence of DM-domain region of Halichoeres. tenuispinis was identical to those of Pseudolabrus japonicus, Pteragogus flagellifera, and showed 94% identity with that of Halichoeres poecioptrerus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.2
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• pp.180-187
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• 2021

This study was conducted to investigate the reproductive characteristics of the Neon damselfish Pomacentrus coelestis in Chuuk lagoon (7°27' N, 151°53' E), Micronesia, Equatorial Pacific Ocean. The specimens used in this study were collected from August 2009 to September 2010 from around the coral reef area at a depth of 3-10 m in the northwest coast of Weno Island. Overall, 228 individuals were collected over 14 months from this area, of which 115 were females and 108 were males. Among 108 males, 30 were found to be hermaphrodites and the sex of 5 individuals could not be determined. The overall sex ratio was approximately 1.06:1 (female:male), and the ratio of sexually active individuals was 0.79:1. The gonadosomatic index (GSI) fluctuated and showed the highest value of 8.43±1.21 in December 2009 and the lowest value of 3.36±0.71 in September 2009 in sexually active females. Males showed the highest GSI value of 2.64±0.93 in June 2010 and the lowest value of 0.35±0.06 in July 2010. Based on the fluctuation of GSI, the trends in the appearance of monthly sexually active individuals, and biopsy of the gonads, P. coelestis was found to be a hermaphrodite species of protogynous type and is considered to be reproductively active throughout the year.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2005.07a
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• pp.33-33
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• 2005

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2003.10a
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• pp.64-64
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• 2003

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.104-104
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• 2004

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.91-95
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• 2012

To examine the sex morph, heterodichogamy, fruiting characteristics and seed viabilities of Acer palmatum, sixty three planted trees were monitered in Wonju-si for two years in terms of their sex morph, flowering and fruiting habit. Most flowers of A. palmatum are pollinated by Apis mellifera, Helophilus virgatus, a few (3.57%) are pollinated by wind. Twenty four trees (42.9%) in 2010, and twenty trees (31.7%) in 2011 were proved protandrous (PA: pollen is shed before stigmas are receptive), thirty two (50.8%) in 2010, thirty trees (47.6%) in 2011 were proved protogynous (PG: stigmas are receptive before pollen is shed). This result means that Acer palmatum has heterodichogamous sexual system. Five trees (7.9%) have changed their sex morphs; 4 trees change the sex morp PA to PG, and one does the sex morph PG to PA. Rates of sound seeds and decayed seeds were significantly different between sex morphs. Rates of sound seeds were 51.6% (2010) and 64.0% (2011) in PA, but 30.4% (2010) and 40.4% (2011) in PG. and rates of decayed seeds did 40.0% (2010) and 31.2% (2011) in PA, but 65.6% (2010) and 56.8% (2011) in PG. The differences of decayed seeds' rates between sex morphs might be related with the timing of insect pests' outbreak.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.131-135
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• 2011

To examine the sex morph, fruiting characteristics and seed viabilities of Acer palmatum var. matsumurae (Koidz.) Makino, the flowers and seed-sets of 101 trees were collected from early April to late October 2010, and floral structure and seed viability were studied. Among investigated 101 trees, 73.3% of trees were protandrous (PA: pollen is shed before stigmas are receptive) and 26.7% were protogynous (PG: stigmas are receptive before pollen is shed). Acer palmatum var. matsumurae has heterodichogamous sexual system. Number of flowers and seed-sets per inflorescence are significantly different between sex morphs, and PA has more flowers and seed-sets per inflorescence than PG. Rates of sound seeds and decayed seeds are significantly different between sex morphs. Rates of sound seeds were 46.4% in PA, but 65.6% in PG. and rates of decayed seeds were 49.6% in PA, but 23.6% in PG. The differences of decayed seeds' rates between sex morphs might be related with the timing of pistil flower blooming and insect pests' outbreak.