• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.368-374
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• 1986

Liparis ingens (Gilbert et Burke) is a demersal fish belonging to Liparidae, widely distributed in the coastal waters of the east coast of Korea. On January 16, 1986, mature adults of Liparis ingens were captured by a demersal gill net near Chongdongchin-ri, Kangwon-do, Korea. The authors stripped eggs and milt, and fertilized on the ship. The eggs were incubated and the larvae were reared in laboratory. The eggs of this species are demersal and adhesive, and are pale yellow, containing many oil globules. Egg diameters were varied from 1.55 to 1.65 mm. The hatching took place in ca. 747 hours after fertilization at the water temperature of $7.09{\sim}10.99^{\circ}C$ and salinity $30.62{\sim}33.98\%0$. The newly hatched larvae were elongate in shape and $4.40{\sim}4.85mm$ in total length with $12{\sim}13$ (abdominal)+40(caudal)=$52{\sim}53$ myomeres. Many melanophores were distributed on the lower jaw, pectoral fins, yolk sac, and ventral line of the tail part. Three days after hatching, the larvae reached 5.15 to 5.25 mm in total length, and the yolk sac was almost absorbed. Some melanophores appeared on the back of auditory vesicles. Seven days after hatching, the larvae attained $5.75{\sim}5.85mm$ in total length.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.235-244
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• 2010

Ultrastructural characteristics of the testis and spermatogenesis of Crassostrea gigas were investigated by Transmission and Scanning Electron microscope observations. The testis is a diffuse organ consisting of branching acini containing differentiating germ cells in a variety of stages. The acinus is surrounded by an intermitent layer of myoepithelial cells andis divided into subcompartments that are partially separated by pleomorphic accessory cells which remain in close contact with germ cells until late stages of development. these accessory cells contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes could be find in the cytoplasm of the accessory cells. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle, subacrosomal material (containing axial rod embedded in a granular matrix), a oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres appear to the distal centriole and plasma membrane. Spermatozoa of C. gigas resemble to those of other investigated ostreids. In particular, the anterior region of the acrosomal vesicle is transversely banded. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The spermatozoon is approximately $42-47{\mu}m$ in length including an oval sperm nucleus (about $0.91{\mu}m$ in length), an acrosome (about $0.42{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9 + 2 structure. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.112-120
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• 2008

A series of experiments were conducted to establish a marine ecotoxicological standard method using marine primary producers, Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, Tetraselmis suecica as candidate test species. Marine diatom, S. costatum was selected as standard test species in terms of the ecological roles and international uses as test species. Test methods and test acceptability criteria are as follows; $72{\sim}96$ hr population growth inhibition $EC_{50}$ as endpoint. Static non-renewal method, and population growth rates over 0.04/hr in control as test acceptability criterium. S. costatum is widely distributed in the world ocean and used for standard species of marine toxicity test method by ISO (International Standardization Organization). Possible salinity ranges for this test method are $20{\sim}35\;psu$, and reproducibility and interlaboratory test results were consistent through the calibration tests. Sensitivity of the test method was comparable or better than other toxicity tests such as rotifer neonate mortality, bioluminescent bacterial inhibition, seaweed sporulation and sea urchin fertilization tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.49-54
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• 2017

We collected and reared Theragra chalcogramma walleye pollock brood-stock for use in natural spawning tests and undertook to obtain domestic pollock via fertilized egg capture, development of fertilized eggs, and absorption of yolk sac after hatching. Whole pollock were caught with trammel and set nets and immediately placed in a deep-sea water tank. Adults were the most common pollock age group (43.0%; n = 86) among the 254 pollock captured in March 2014 with 57.9% (n = 147) being captured off Southern Gosung, Korea. The main spawning period of pollock is February (spawning phase of 91% of pollock). From the deep-sea tank, we collected 1640 mL of naturally fertilized eggs (~820,000 eggs) from 12 spawning events occurring between February 4 and 22 2015. The floating/ live eggs were maintained in deep-sea water tanks at $5.5{\pm}0.2^{\circ}C$. Egg size was $1.5{\pm}0.03mm$. Six hours after fertilization the eggs were at the 2 cell stage, and the eggs hatched approximately 340 hours after collection. At hatching, larval length and yolk sac area were $5.2{\pm}0.25mm$ and $9.5{\pm}1.00mm^2$ (100%), respectively. Four days after hatching, the yolk sac area was $2.2{\pm}0.53mm^2$ ($23.1{\pm}5.55%$). This is the first report of collection of naturally fertilized eggs from pollock and their subsequent hatching while held in an indoor deep-sea water tank. The results suggest that such collection could assist in the recovery of pollock resources and the possibility of domestic rearing of cultivated larvae.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.605-611
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• 2015

A synthetic strain of ducks (Anas platyrhynchos) was developed by introducing genes for long duration of fertility to be used as mother of mule ducklings and a seven-generation selection experiment was conducted to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. Reciprocal crossbreeding between Brown Tsaiya LRI-2 (with long duration of fertility) and Pekin L-201 (with white plumage mule ducklings) ducks produced the G0. Then G1 were intercrossed to produce G2 and so on for the following generations. Each female duck was inseminated 3 times, at 26, 29, and 32 weeks of age. The eggs were collected for 14 days from day 2 after AI. Individual data regarding the number of incubated eggs (Ie), the number of fertile eggs at candling at day 7 of incubation (F), the total number of dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) with plumage colour were recorded. The selection criterion was the breeding values of the best linear unbiased prediction animal model for F. The results show high percentage of exhibited heterosis in G2 for traits to improve (19.1% for F and 12.9% for H); F with a value of 5.92 (vs 3.74 in the Pekin L-201) was improved in the G2. Heritabilities were found to be low for Ie ($h^2=0.07{\pm}0.03$) and M ($h^2=0.07{\pm}0.01$), moderately low for Dm ($h^2=0.13{\pm}0.02$), of medium values for H ($h^2=0.20{\pm}0.03$) and F ($h^2=0.23{\pm}0.03$). High and favourable genetic correlations existed between F and Dm ($r_g=0.93$), between F and H ($r_g=0.97$) and between Dm and H ($r_g=0.90$). The selection experiment showed a positive trend for phenotypic values of F (6.38 fertile eggs in G10 of synthetic strain vs 5.59 eggs in G4, and 3.74 eggs in Pekin L-201), with correlated response for increasing H (5.73 ducklings in G10 vs 4.86 in G4, and 3.09 ducklings in Pekin L-201) and maximum duration of the fertile period without increasing the embryo mortality rate. The average predicted genetic response for F was 40% of genetic standard deviation per generation of selection. The mule ducklings' feather colour also was improved. It was concluded that this study provided results for a better understanding of the genetics of the duration of fertility traits in the common female duck bred for mule and that the selection of a synthetic strain was effective method of improvement.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.82-89
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• 2013

The spawning behavior, development of eggs and larvae of the Five striped damselfish, Abudefduf vaigiensis were studied. The Five striped damselfish were caught at Dolsan Island, Yeosusi, Jeollanamdo from May in 2011. As a result of observation, male fish attracted female after cleaning the rock. Female left after spawning and male protected their eggs until they had hatched out. The fertilized eggs were elliptical in shape (mean long diameter: 1.06 mm; mean short diameter: 0.55 mm) and transparent. Larvae hatched at 53 hrs after fertilization in $24.5{\sim}26.5^{\circ}C$(mean $25.0^{\circ}C$). The newly hatched larvae were 2.55~2.86 mm (mean 2.71 mm, n=10) in total length and their mouth and anus were already opened. They began to eat rotifer and transformed to postlarva stage. 3 days after hatching postlarva was measured 2.74~2.97mm(mean 2.84 mm, n=10) in total length. 10 days after hatching postlarva was measured 3.85~4.20mm(mean 4.00 mm, n=10) in total length with dosal fin rays IV-5; ventral fin rays I-3; caudal fin rays 1~2.