• Korean Journal of Ichthyology
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• v.24 no.2
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• pp.125-130
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• 2012

We describe early morphological development in laboratory-reared specimens of the brown croaker, Miichthys miiuy, in relation to fin differentiation, head dimensions, and squamation. From the yolk sac stage to the flexion larval stage (a period of 12 days following hatching, at which time the larvae were <4.2 mm in total length; TL) we observed the presence of a fin-fold around the body, while the caudal fin appeared rounded and lacked scales. Rays developed in the dorsal, anal, and pectoral fins in a process that was almost complete in larvae 12 days, while ray segmentation occurred between 26 and 29 days of age. Elongation of the middle rays of the caudal fin was initiated at 32 days, and the rays were remarkably elongated by 37 days. By 68 days the caudal fin was lanceolated (50.7 mm TL). Scales began to develop from the midlateral lines of the caudal peduncle at 9.1mm TL (28 days), eventually encompassing the entire operculum (22.1 mm TL; 44 days). The head dimensions were largely stabilized at >12 mm TL (30 day).

• Korean Journal of Ichthyology
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• v.2 no.2
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• pp.138-148
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• 1990

The influence of starvation on morphological change of the red sea bream larvae was examined at Song-ji fish hatchery, Tongyong-Gun, Kyongnam Provice in July 1988. The results obtained are as follows: 1) The larvae of red sea bream began to feed on rotifers in 2 days after hatching. In case of non-feeding, all of the larvae died in 5 days after hatching and the larvae which feeding delayed 1 and 2 days from normal first feeding schedule also died 100 in 6 days after hatching. 2) With the exhaustion of the yolk, the total length, body length, myotome height and gut height of unfed larvae decreased. 3) The ratio of height to myotome height in unfed larvae has declined most rapidly compare to other demensions while starving. At 5 days after hatching, the ratios of these of starving larvae and fed larvae were 0.306 and 0.010, respectively. 4) The morphology of starving larvae at 6 days after hatching are characterized as sharpened jaw, projected edge of lower part of clavicle and slender gut.

• Korean Journal of Environmental Biology
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• v.30 no.2
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• pp.136-142
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• 2012

Acute toxicity test of heavy metal (Cd, Cu, Zn) were examined using the hatching rates of fertilized eggs in the oliver flounder, Paralichthys olivaceus. Eggs were exposed to Cd, Cu, Zn (0, 10, 100, 500, 1000, 2500, 5000 ppb) and then normal hatching rates were investigated after 48 h. The normal hatching rates in the control condition (not including Cd, Cu and Zn) were greater than 80%, but suddenly decreased with increasing of heavy metal concentrations. Cd, Cu and Zn reduced the normal hatching rates in concentration-dependent way and a significant reduction occurred at concentration grater than 1000, 100, 100 ppb, respectively. The ranking of heavy metal toxicity was Zn>Cu>Cd, with $EC_{50}$ values of 584, 1015 and 1282 ppb, respectively. The no-observed-effect-concentration (NOEC) and the lowest-observed-effect-concentration (LOEC) showed each 100 and 500 ppb of normal hatching rates in exposed to Cu and Zn. The NOEC and LOEC of normal hatching rates in Cd were 500 ppb and 1000 ppb, respectively. From these results, the normal hatching rates of P. olivaceus have toxic effect at greater than the 100 ppb concentrations in Cu, Zn and the 500 ppb concentrations in Cd in natural ecosystems. These results suggest that biological assay using the normal hatching rates of P. olivaceus are very useful test method for the acute toxicity assessment of a toxic substance as heavy metal in marine ecosystems.

• Journal of Aquaculture
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• v.21 no.3
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• pp.176-180
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• 2008

This study clarified biochemical overripeness characterization of ovulated eggs of Anguilla japonica and suggested a method maintained overripeness after ovulation for high hatching rates. In maturated Japanese eel eggs, the relationships between fertilization rate and hatching rate, and fertilization and survival rates were measured. DNA contents showed the significantly low 0.653 pg/ug protein in 20% downward hatching rate trial with decrease of hatching rate(P<0.05), whereas RNA/DNA ratio showed the significantly high 1.058 in 20% downward hatching rate trial(P<0.05). And activities of total alkaline protease and ACPase according to the hatching rate groups did not show the significant difference(P>0.05). The protein contents were assayed the significantly high 186.16 ug/mg protein in 20% downward hatching rate trial(P<0.05). However, the overripened eggs had lowed hatching rate, because of stimulate the overripening of normal maturated eggs due to the continuous supplement of protein (vitellogenin). We suggested that need to reduce supplement speed or interception of vitellogenin produced in live for prevent overripeness of maturated eggs after ovulation

• Korean Journal of Ichthyology
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• v.9 no.1
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• pp.15-21
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• 1997

The influence of delayed(1, 2, 3, 4 days) feeding and starvation on morphological change and survival rate of the spotted sea bass larvae was examined at the KORDI laboratories which located at Poryong Power Plant, Poryong-gun, Chungchongnam-do in November, 1996. 1. The larvae of spotted sea bass began to feed on rotifers at 5 days after hatching. In case of non-feeding, all of the larvae died at 9 days after hatching. The larvae which fed 1 day after the normal first feeding schedule(1 day delayed) grew normally and 2 days delayed groups showed 5.3% in survival rate at 9 days after hatching. In case of non-feeding and 3 or 4 days delayed groups, all of the larvae died between 9 and 10 days after hatching. 2. In case of non-feeding, total length of the larvae decreased gradually. 3. The percente ratio of gut height and mytome height to standard length in starved larvae has declined most rapidly compare to other demensions during the non-feeding period. The percente ratio of gut height to mytome height had also difference between unfed and fed larvae. At 9 days after hatching, the ratio of that between fed and unfed larvae were 84.5 % and 52.4 %, respectively. 4. The morphology of starving larvae were characterized as sharpened jaw, projected edge of lower part of clavicle and bending trunk with slenger gut.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.295-302
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• 2007

We investigated starvation of hatching larvae, occasional artificial hatching and incubation method to establish year-round rearing of the wild silkmoth, Antheraea yamamai. In the test of starvation of hatching larvae for brushing at a time, the survival rate of the fourth instar of larvae starved for 1 day after hatching in $25^{\circ}C\;and\;5^{\circ}C$ was 83.3% and 96.0%, respectively. The result represents that the survival rate is high at low temperature during starvation. In the occasional artificial hatching test for multi-times rearing of A. yamamai, the useful hatchability is high at $5^{\circ}C$ in case of preserving eggs for 2 months from incubation time, and at both $2.5^{\circ}C\;and\;0^{\circ}C$ in case of over 6 months. A new incubation method with pre-incubation at $15^{\circ}C$ and 24 D photoperiod showed high hatchability about 80% for only 2 days compared with hatching for 5-6 days in traditional incubation method with the preservation at $25^{\circ}C$.

• Korean Journal of Ichthyology
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• v.35 no.2
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• pp.83-90
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• 2023

Five days after hatching in Konosirus punctatus, the larvae were 5.86~6.21 mm (mean 5.96 mm) in TL and ossified parasphenoid, prefrontal, premaxillary, dentary. Sixteen days after hatching, the larvae were 9.66~10.18 mm (mean 9.96 mm) in TL and ossified prootic, opisthotic, ectopterygoid, and epihyal. Twenty-five days after hatching, the larvae were 11.02~12.64 mm (mean 11.03 mm) in TL and ossified supraclavicle, posttemporal, four actinost. Twenty-eight days after hatching, the larvae were 11.98~12.81 mm (mean 12.34 mm) in TL and ossified frontal, pterotic, epiotic, exoccipital, basioccipital, preorbital, maxillary, hyomadibular, preopercle, opercle, hypohyal. Thirty-six days after hatching, the larvae were 15.26~16.39 mm (mean 16.11 mm) in TL and ossified scapula. 37 days after hatching, the larvae were 15.33~16.87 mm (mean 16.25 mm) in TL and ossified ethmoid, nasal, parietal, supraoccipital, and suborbital. Forty-five days after hatching, the larvae were 20.01~21.83 mm (mean 21.14 mm) in TL, and the shoulder girdle was completed by coracoid formation. Forty-eight days after hatching, the larvae were 22.46~24.03 mm (mean 23.20 mm) in TL and ossified articular and subopercle. When the juvenile reached 27.11~34.09 mm (mean 30.11 mm) in TL (53 days after hatching) completed ossification of the cranium, vertebrae, pelvic girdle, shoulder girdle, caudal bone, and pterygiophore.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.433-441
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• 1997

체외성숙과 수정된 돼지 난자의 체외발달능이 체외배발생 배양액인 NCSU 배양액에 0.4% BSA, 10% 혈청 혹은 아미노산(2% BME 아미노산 용액과 1% MEM 아미노산 용액)을 첨가함으로써 조사되었다. 본 실험에 공시된 난자는 체외수정 후 30시간 (2-세포기) 혹은 48시간 (2~4-세포기)에 회수하였다. 실험 I에서 0.4% BSA가 첨가된 NCSU 배양액에서 2-세포기 난자들의 배양경과시간에 따른 발달능을 조사한 결과, 배양 후 72시간 (체외수정 후 102 시간)에 상실배와 배반포기가 나타났으며, 배양 후 120시간째(체외수정 후 150시간)에도 팽창된 배반포까지만 발달하였다. 실험 II는 체외수정 후 48시간의 분할된(2~8-세포기) 난자들의 핵과 외관적 분할구와의 수적 차이를 조사한 결과, 2~4-세포기보다는 5-세포기 이상에서 핵과 분할구의 조화에 차이가 많았다. 실험III에서는 BSA, 혈청 혹은 아미노산이 첨가 혹은 무첨가된 배양액내에서 2~4-세포기 난자들의 배반포 후 부화능력을 조사한 결과, 모든 군에 있는 난자들은 팽창된 배반포까지 발달할 수 있었던 반면, 난자의 부화는 아미노산 혹은 혈청이 포함된 배양액에서만 일어났다. 더욱이 상실배와 배반포시기에 혈청의 첨가는 부화 배반포기 배의 발달을 현저히 증가시켰다. 이상의 결과로 미루어 볼 때, 배양액내에 대한 아미노산과 혈청의 첨가는 돼지 배반포의 부화를 유도할 수 있다고 본다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.331-334
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• 2002

탄산수내 REEs의 함량과 거동특성을 알아보기 위해 암석시료, 탄산수 및 침전물에 대한 REEs 분석을 실시하였다. 탄산수가 산출되는 인접지에서 채취한 암석시료들은 물의 유형에 따라 큰 농도변화를 보여주지 않으며, 대체적으로 LREEs가 부화된 특성을 보여주고 있다. 유형에 따른 탄산수의 REEs 농도변화는 서로 상이한데, Na-HCO$_3$ 유형은 강한 HREE의 부화를 보여주지만, Ca-HCO$_3$ 유형은 HREE의 부화를 보여주지 않고 감소하는 경향을 보이며, 화학적으로 중간 유형에 속하는 Ca-Na-HCO$_3$ 유형 탄산수는 Eu을 제외하고는 전체적으로 flat한 분포를 보여준다. 탄산수에서 침전된 침전물과 침전물을 제거한 물의 REE의 유형은 침전물이 발생되기 전의 탄산수와 유사한 경향을 보이지만, 침전물의 발생으로 인한 특징적이고 강한 anomalies를 보여준다. 침전된 침전물의 REEs 특성은 침전물이 발생되기 전의 원 탄산수와 거의 유사한 분포특성을 보여준다. 반면에 침전물을 제거한 탄산수에서는 탄산염침전물의 침전과 연관되어 매우 강한 Eu anomalies를 보여주며, 대체적으로 HREE가 부화된 특성을 보여주었다. 탄산수내 가장 우세한 REE 종은 CO$_3$$^{2-}$ 종이며, CO$_3$$^{2-}$ 복합체 때문에 REEs의 분별작용 (HREE의 부화)이 일어나는 것으로 판단되 었다.

• Korean journal of applied entomology
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• v.32 no.4
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• pp.450-456
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• 1993

We investigated effects of a topical treatment of methoprene(0.5-5.0$\mul$/egg), a juvenLle horm mane analogue, on embryo development in the gypsy moth, Lymantri$\alpha$ dispar. Methoprene lowered egg hatching rate, and also reduced the mean wet weights of hatched 1st instar larvae w with the most effect shown at the highest concentration. The differences in protein(p < 0.01) and carbohydrate(p < 0.05) contents between control and methoprene(5$\mul$/ egg) treatment g groups were observed during embryo development.