• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.161-165
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• 2001

Artificial fertilization (dry method) of mature right-eye flounder, Limanda yokohamae (female : 25.1~30.4 cm in total length (TL), male : 24.5~28.5 cm in TL), obtained from the fish market in Dolsan-do, Yosu was performed in the Fisheries Exhibition. Hatched larvae and juveniles were reared to describe their morphological development. Newly hached larvae attained 3.13~3.42 mm in TL. Their eyes were yellowish brown and their mouth and anus were not yet opened. Three to six days after hatching the larvae attained 3.35~4.61 mm in TL. Their mouth and anus were open and the yolk sac was almost absorbed. Feeding activity increased as the mouth became larger. At 25 days, the larvae attained 5.47~5.91 mm in TL. The caudal notocord was flexed $45^{\circ}$ upward. At 35 days, the larvae attained 6.83~7.60 mm in TL. Rays of the dorsal and anal fins were formed, and the left eye was moved slightly to the right side of the head. At 55 days, the juveniles attained 9.38~11.73 mm in TL. The left eye was moved completely onto the right side. All of the fins had complete set of the fin rays, and the juveniles spent most of the time on the bottom resting on their blind side (D. 68~70 : A. 50~52 : P. 11: V. 6 : C. 18~19).

• Korean Journal of Ichthyology
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• v.13 no.2
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• pp.129-135
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• 2001

Matured adults of Siniperca scherzeri were collected from Soyangdam and Hongchun river, Gangwon-do, Korea. The fertilized eggs were hatched and reared in the laboratory of the Korea Ocean Research and Development Institute. Osteological development of the larvae and juveniles of Siniperca scherzeri were investigated. Three days after hatching, the larva (6.12 mm in total length: TL) had partly ossified parasphenoid, clavicle, hyomandibular, preopercle, opercle and jaw bones with 7 to 8 canine teeth. The ascending process of premaxillary and ca 19 and 23 teeth on the premaxillary and dentary, respectively, were ossified at 10 days after hatching. Also at 10 days, the vertebral columns of the larvae (6.85 mm in TL) were posterioly ossified to the 5~7th vertebra, and ossification was completed in the juvenile (10.99 mm in TL) on the 22 nd day. Thus ossification began 3 days after hatching, and was completed 22 days after hatching.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.71-77
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• 2015

Morphological changes in eggs and larvae of spotted knifejaw, Oplegnathus punctatus were observed by cultivation of fertilized eggs to juvenile stage. Fertilized egg was demersal and transparent. The egg has one oil glouble and its size ranged 1.01~1.15 mm ($1.08{\pm}0.10mm$; $mean{\pm}SD$, n=20). Culture chambers were maintained $22.5{\sim}24.5^{\circ}C$ in water temperature and 33.5~34.5ppt in salinity. It took 25 mins from fertilization to the blastoderm stage, 55 mins to 2 cell stage and 20 hrs 50 mins to hatching. Newly hatched yolksac larvae ranged 2.59~3.02 mm ($2.81{\pm}0.25mm$, n=5) in total length, and mouth and anus were not still open. Yolk and oil globule were absorbed 2 days after hatching (DAH). Flexion larvae in 12 DAH ranged 3.02~3.07 mm TL ($3.04{\pm}0.04mm$), and the caudal fin grew to fan-shaped, melanophores appeared on top of digestive canal.

• Korean Journal of Ichthyology
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• v.27 no.1
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• pp.26-32
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• 2015

The histological structure of the heart in Pseudorasbora parva was investigated by light microscope. The heart consisted of four consecutive chambers, the sinus venosus, atrium, ventricle and bulbus arteriosus. The wall of the sinus venosus was divided into endocardium, myocardium and epicardium, and the walls of the atrium and ventricle were divided into endocardium, subendocardium, myocardium, subepicardium and epicardium, and the wall of the bulbus arteriosus was divided into endocardium, subendocardium (ridge tissue), middle layer, subepicardium and epicardium. The valves were observed in the sinoatrial, artrioventricular and bulboventricular junctions. The sinus venosus wall was mostly made up of collagen. The rings of tissue were observed at the sinoatrial junction. The atrium was composed of a spongy trabeculate myocardium surrounded by an external rim of thin myocardium, and collagens were distributed in the subepicardium and trabeculae. The ventricle was a spongy myocardium with vessels in subepicardium. In the subepicardium and trabeculae of the ventricle, collagens were distributed. In the bulbus arteriosus, the diameter and length of the ridges were differed. The endocardial cells were convex and the non-clustered subendocardial cells showed irregular shapes. The cells of the middle layer were arranged into incomplete layers that showed different orientations. The subepicardium was formed by cells of different morphology. Collagens and elastins were demonstrated in the subendocardium, middle layer and subepicardium of the bulbus arteriosus. The epicardium was a single layer composed of flattened cells.

• Korean Journal of Ichthyology
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• v.29 no.3
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• pp.218-223
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• 2017

Using both light and scanning electron microscopies, it was investigated on the visual cells as well as the eyes of Macropodus ocellatus (Pisces, Osphronemidae). This species had a circular lens and yellowish cornea. The eyes had $3.5{\pm}0.2mm$ which is $31.1{\pm}3.0%$ in a percentage of eye diameter relative to head length. The retina ($158.2{\pm}10.6{\mu}m$) was built of several layers, including the visual cell layer which consists of three types of cells: single cons ($27.8{\pm}1.6{\mu}m$) and equal double cone ($33.9{\pm}3.7{\mu}m$), and large rods ($57.3{\pm}1.3{\mu}m$). The visual cell layer then was classified into the correct pattern. All visual cells were clearly distinguished from two parts (inner and outer segments). The elongated rod cells were extend to the bottom of the retinal pigment epithelium. In scanning electron microscopy, the outer segment links to inner segment by so-called calyceal piles. The M. ocellatus single and double cones appearance form a flower-petal arrangement, which is a regular mosaic pattern that contains quadrilateral units by four double cones surrounding a single cone.

• Journal of Life Science
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• v.28 no.9
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• pp.1062-1067
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• 2018

Reliable labeling of fish products can reassure consumers regarding the identity and quality of seafoods. Therefore, techniques that can identify adulteration or mislabeling are valuable. To rapidly identify two Trachurus species, Trachurus japonicus and Trachurus novaezelandiae, a highly efficient, rapid, duplex polymerase chain reaction (PCR) having two species-specific primers simultaneously was identified. This species-specific primer focused on a single nucleotide mismatch in the 3'-terminal base of a primer designed in the mitochondrial cytochrome c oxidase (COI) subunit I DNA. To optimize the duplex PCR condition, gradient PCR reactions were conducted to determine the primer annealing temperature and the primer concentration. The PCR's product was observed on the gel, suggesting that DNA molecules may be useful in differentiating the two species. The length of the amplification fragments were 103 bp for Trachurus japonicus and 214 bp for Trachurus novaezelandiae, which, along with the species-specific primer visualized by agarose gel electrophoresis, enabled accurate distinction of the species of the Trachurus genus. These results indicate that the duplex PCR, which has a species-specific primer based on single nucleotide polymorphism (SNP), can be useful for rapidly differentiating the two species of Trachurus. This duplex PCR analysis is simple, rapid, and reliable, and could be beneficial to protecting consumers' rights.

• Development and Reproduction
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• v.12 no.3
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• pp.215-220
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• 2008

Sex differentiation process of the spotted Black Bullhead, Pseudobagrus koreanus, was investigated using fish samples of different age after hatching. The primordial germ cells appeared separately under air bladder in 1-day larva (total length: $6.63{\sim}6.95\;mm$). The primordial gonad with a genital ridge developed in 5-day prelarva ($7.50{\sim}9.36\;mm$). The ovarian differentiation started in about 25-day juvenile ($11.58{\sim}13.21\;mm$). The somatic tissues enlongated in the tip of one end of undifferentiated gonad and fused each other. Thus a small ovarian cavity appeared. The testicular differentiation was initiated in 30-day juvenile ($12.19{\sim}13.72\;mm$). The rudiment of sperm duct was appeared in the lower part of the undifferentiated gonad. In 50-day juvenile ($16.28{\sim}17.06\;mm$), the ovary started to fill with peri-nucleolus oocytes, and the spermatogonia started to develop. In 250-day juvenile ($35.49{\sim}51.12\;mm$), the ovary became bigger and filled with oocytes, and the number of spermatogonia started to increase. Considering these results, the spotted Black Bullhead could be a differentiated type in sex differentiation and gonochorism in sexuality.

• Journal of Aquaculture
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• v.9 no.3
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• pp.187-194
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• 1996

Sixteen strains of marine rotifer, Braohionus plicatilis were isolated from salt pond, estuary and lagoon. Among 16 strains, 2 strains were large (L)-type and the others were small (S) or ultra small (US)-type. Four strains of fresh water rotifer, B. calyciflorus were isolated from commercial fish ponds. The size of lorica and resting egg were measured. In B. plicatilis, the range of lorica length from S-type and S-type were $244.3{\~}255.3\;{\mu}m$ and $131.0{\~}165.8\;{\mu}m$, respectively. The major axis of resting egg in the marine rotifer were $93.7\~116.4\;{\mu}m$ for S-type and $142.4{\~}145.5\;{mu}m$ for L-type, respectively. In freshwater rotifer, B. calyciflorus, the size range of lorica and major axis of resting egg were $211.8\~229.9\;{\mu}m$ and $126.8\~140.2\;{mu}m$, respectively. The size of freshwater rotifer was larger than that of S-type marine rotifer, but smaller than that of L-type one. Growth and formation of resting egg of B. plicatilis were different among the strains. The maximum density of S-type and L-type rotifer was 753.3 inds./ml for H-S strain and 220 inds./ml for O-L strain, respectively. The largest production of resting egg of S-type and L-type rotifer were 86.7 inds./ml for YY-S strain and 45.8 inds./ml for O-L strain, respectively.

• Development and Reproduction
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• v.4 no.2
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• pp.195-201
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• 2000

Sex differentiation process of the spotted sea bass, Lateolabrax maculatus, was investigated by histological method. The fish samples were collected from just after hatching to 365 days later. The primordial germ cells and genital ridge were appeared separately hanging under air bladder in 30-day larva (total length: 11.7~13.2 mm), and were unified into the undifferentiated gonads in 40-day larva (12.5~14.0 mm). The ovarian differentiation was started in 60-day juvenile (23.6~27.0 mm). The somatic tissues were elongated in tip of both ends of undifferentiated gonad and were fused each other. The complete ovarian cavity was appeared in 80-days juvenile(33.1~42.5 mm). The testicular differentiation was initiated in 70-day juvenile (24.8~31.6 mm). The rudiment of sperm duct was appeared in the center of the undifferentiated gonad. The meiosis of germ cells in the ovary was started in 168-day juvenile (88.0~115.4 mm). In 287-day juvenile (175.1~233.6 mm), the ovary was filled with both of chromatin stage and perinucleolus stage oocytes. The meiosis of male germ cells was started in 245-day juvenile (124.4~168.3 mm). However, the seminiferous tubules of testis were filled with numerous sperm in 365-day juvenile (162.5~253.8 mm). The sex ratio of male and female was 1:1.38. Considering these results, the spotted sea bass was showed differentiated type in sex differentiation and gonochorism in sexuality.

• Journal of Life Science
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• v.28 no.6
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• pp.639-647
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• 2018

A new heat shock protein 70 was identified in red-spotted grouper (Epinephelus akaara) based on an expression analysis. The cDNA of red-spotted grouper Hsp70 (designated RgHsp70) was cloned by the rapid amplification of cDNA ends (RACE) techniques. The full-length of RgHsp70 cDNA was 2,152 bp, consisting of a 5'-terminal untranslated region (UTR) of 105 bp, a 3'-terminal UTR of 274 bp, and an open reading frame (ORF) of 1,773 bp that encode a polypeptide of 590 amino acids with a theoretical molecular weight of 64.9 kDa and an estimated isoelectric point of 5.2. Multiple alignment and phylogenetic analyses revealed that the RgHsp70 gene shares a high similarity with other Hsp70 fish genes. RgHsp70 contained all three classical Hsp70 family signatures. The results indicated the RgHsp70 is a member of the heat shock protein 70 family. RgHsp70 mRNA was predominately expressed in the liver, with reduced expression noted in the head-kidney tissues. The expression analysis of different water temperatures (21, 18, 15 and $12^{\circ}C$) for sampled livers revealed that expression gradually increased at $12^{\circ}C$ compared to $21^{\circ}C$. In this study, the effects of water temperature lowering on the physiological conditions were investigated, and the results revealed that novel RgHsp70 may be an important molecule involved in stress responses.