• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.238-244
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• 2012

Toxic effects of heavy metal (Pb, Cr, As) were examined by the hatching rates of fertilized eggs in the oliver flounder, Paralichthys olivaceus. Eggs were exposed to Pb, Cr, As (0, 10, 100, 500, 1,000, 2,500, 5,000 ppb) and then normal hatching rates were investigated after 48 h. The normal hatching rates in the control condition (not including heavy metal) were greater than 80%, but suddenly decreased with increasing of heavy metal concentrations. Pb, Cr and As reduced the normal hatching rates in concentration-dependent way and a significant reduction occurred at concentration grater than 100, 100, 500 ppb, respectively. The ranking of heavy metal toxicity was Cr>As>Pb, with $EC_{50}$ values of 415, 518 and 1,029 ppb, respectively. The no-observed-effect-concentration (NOEC) and lowest-observed-effect-concentration (LOEC) show each 100 bbp and 500 ppb of normal hatching rates in exposed to Pb and As. The NOEC and LOEC of normal hatching rates in Cr were 10 ppb and 100 ppb, respectively. From these results, the normal hatching rates of P. olivaceus have toxic effect at greater than the 100 ppb concentrations in Pb, As and the 10 ppb concentrations in Cr in natural ecosystems. These results suggest that biological assay using the normal hatching rates of P. olivaceus are very useful test method for the toxicity assessment of a toxic substance as heavy metal in marine ecosystems.

• 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.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.239-245
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• 1998

The distributions and relative frequencies of insulin-, glucagon-, and somatostatin-immunoreactive cells in the pancreas of the duck(Anas platyrhynchos platyrhyncos, Linne) were investigated immunohistochemically on 23 days of incubation, at hatching, 1 week, 2 weeks, 3 weeks, 5 weeks, 6 weeks, 7 weeks, 9 weeks, 10 weeks, and 32 weeks after hatching. In the duck pancreas on 23 days of incubation and at hatching, mammalian type islets(mixed type) were only observed, thereafter three type's islets(mamalian, A and B type's islets) were identified. Insulin-immunoreactive cells were detected in central region of the islets, while glucagon- and somatostatin-immunoreactive cells were detected in marginal region of light(B type) or mammalian type islets, and in central region of dark islets(A type). Insulin-, and somatostatin-immunoreactive cells were also detected in the exocrine regions. In this region the insulin-immunoreactive cells were detected from 23 days of incubation to 6 weeks, however not detected after 7 weeks. At hatching the relative numbers of somatostatin-immunoreactive cells were more frequent than those of other groups, and then decreased with ages.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.232-238
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• 1998

The distributions and relative frequencies of bovine chromogranin(BCG)-, serotonin-, and bovine pancreatic polypeptide(BPP)-immunoreactive cells in the pancreas of the duck(Anas plaryrhynchos plaryrhyncos, Linne) were studied immunohistochemically on 23 days of incubation, at hatching, 1 week, 2 weeks, 3 weeks, 5 weeks, 6 weeks, 7 weeks, 9 weeks, 10 weeks, and 32 weeks after hatching. In the exocrine portions, the relative frequencies of BCG- and serotonin-immunoreactive cells tend to decrease according to ages. BPP-immunoreactive cells first appeared 1 week after hatching, and thereafter decreased. These cells were mainly observed in the exocrine pancreas and marginal region of the pancreatic islets. In the endocrine portions, BCG-, serotonin- and BPP-immunoreacteve cells disappeared 2 weeks, 9 weeks and 5 weeks after hatching, respectively.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.461-466
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• 1998

The histological profiles and endocrine cells in the bursa of Fabricius of the duck (Anas platyrhynchos platyrhyncos, Linne) were studied at 23 days of incubation, at hatching, 1 week, 2 weeks, 3 weeks, 5 weeks, 6 weeks, 7 weeks, 9 weeks, 10 weeks and 32 weeks after hatching. Histologically epithelium of bursa Fabricius were pseudostratified columnar and simple columnar epithelium. Numerous lymphatic follicles and well developed plica were observed in this study. The sections were reacted immunohistochemically using antisera specific to bovine chromogranin(BCG), serotonin and somatostatin antisera using immunohistochemical methods. A few number of BCG-immunoreactive cells were detected from 23 days of incubation to 5 weeks after hatching and serotonin-immunoreactive cells were also observed from 23 days of incubation to 3 weeks after hatching. No somatostatin-immunoreactive cells were detected in this study.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.15-22
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• 2009

An artificial breeding method was carried out to investigate development of eggs and the early life history of Iksookimia longicorpa. The eggs of the female were obtained by injecting gonadotropin (LHRH) and fertilizingby the dry method in the laboratory. The mature eggs were separate, demersal, light yellowish, and averaged $1.53{\pm}0.07mm$ in diameter. In water temperature of $23{\sim}25^{\circ}C$, the eggs hatched in 50~72 hours after fertilization, and their lengths reached $5.1{\pm}0.23mm$ in total length. On Day 4 after hatching, they averaged $7.1{\pm}0.47mm$ in total length and their yolk sacs were completely absorbed. From 25 days after hatching, they attained a juvenile stage reaching $12.8{\pm}0.49mm$ in total length. On the 100th dayafter hatching, their band patterns and external form were similar to those of adults, and they averaged $38.5{\pm}2.95mm$ in total length.

• 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 Fisheries and Aquatic Sciences
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• v.48 no.3
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• pp.362-367
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• 2015

We followed the development of Pacific herring Clupea pallasii larvae after natural hatching in Korean coastal waters off Dadaepo, where the water temperature was $9^{\circ}C$. Twenty days after hatching, the larvae had (i) reached a total length (TL) of 10.8-12.2 mm, (ii) developed 9-11 dorsal fin rays, and (iii) branched melanophores along the dorsal line of the gut in the anterior half of the body and along the posterior half of the dorsal and ventral line. Thirty days after hatching, the larvae had reached 12.2-13.5 mm TL, and the number of dorsal fin rays had increased to 13-14. Thirty-five days days after hatching, the larvae had reached 14.0-14.7 mm TL, and the posterior ends of their notochords had begun to flex upward. Forty-five days days after hatching, the larvae had (i) reached 15.6-15.9 mm TL, (ii) a complete set of dorsal fin rays (15-16), (iii) 12-13 anal fin rays, and (iv) branched melanophores along the dorsal part of the lateral surfaces of the head behind the caudal terminus. Preflexion, flexion and postflexion stage larvae had TL values of 13.5 mm, 14.0-15.3 mm, and 15.6-15.9 mm, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.471-477
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• 2008

Development of egg, larvae and juveniles for the Pacific mackerel, Scomber japonicus are described following natural fertilization in the indoor tank of $25^{\circ}C$ water temperature. Following a routine hormone treatment technique for the brood stock, male and female mackerels were artificially matured by intramuscular injections of LHRHa at a dosage of $400{\mu}g/kg$ body weight (BW)+Domperidone at a dosage of $4{\mu}g/kg$ body weight (BW) to induce maturation in a separate aquarium and induced natural spawning. Fertilized eggs were ca. 1.0 mm in diameter; spherical in shape with a single oil globule; pelagic and non-adhesive. Hatching occurs 41 hours after fertilization at $23-24^{\circ}C$. The newly hatched larvae was 3.03 mm in average total length (ATL), the mouth and anus were not open, oil globule located in posterior end of yolk sac, and preanal length was 42.8% of TL. The larvae measuring 2.89 mm ATL, almost absorbed yolk sac and oil globule material in 2 days after hatching, in which the mouth and anus were open. Melanophores, branch or star in shape were observed on the top of head, peritoneal region and along the ventral contour. In 13 days after hatching, the larvae was 6.88 mm ATL, its posterior end of notochord began to flex upward, finfold of caudal fin appeared, jaw teeth were already formed. In 19 days after hatching, the larvae was 7.71 mm ATL completed only caudal fin rays (9+8), and preanal length was 49.4% of TL. In 37 days after hatching, the larvae was 27.4 mm ATL already completed all the fins, and preanal length was 59.9% of TL.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.371-376
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• 2012

This study was conducted to predict the hatching time of eggs of Lycorma delicatula, to select an effective environmentally-friendly agriculture material (EFAM) and to evaluate the attraction effect of brown sticky traps for controling of Lycorma delicatula nymph and adults. Eggs hatched 55.9, 26.8, 21.6 days after incubation at 15, 20, $25^{\circ}C$ with 14L:10D condition and the hatching rates of egg were 61.9, 57.8, 30.4%, respectively. At high temperature conditions, egg development periods were shorter and the hatching rate was lower. The relationship between temperature and developmental rate was expressed by the linear equation Y=0.0028X-0.0228, $R^2$=0.9561. The low temperature threshold of eggs was $8.14^{\circ}C$ and the thermal constant required to reach larva was 355.4 DD. According to this relationship, the mean estimated hatching date was $22^{nd}$ May. The effective EFAM was natural plant extract, sophora extract, derris extract to nymph and natural plant extract, pyrethrum extract, sophora extract to adult. Among three colors of sticky trap : brown, blue and yellow, the brown sticky trap was the most attractive to nymphs and adults of L. delicatula over a 2 weeks trial period. It suggested that the brown sticky trap could be a very useful and environment-friendly control method for nymphs and adults of L. delicatula.