• Ocean and Polar Research
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• v.40 no.3
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• pp.161-167
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• 2018

We examined the effect of salinity and water temperature on hatching and survival rates of fertilized eggs of hybrid grouper (Epinephelus fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) at different developmental stages, determining optimal conditions for their long-distance transportation. Deformities and hatching rates of fertilized grouper eggs were observed at salinities of 24, 27, 30, 33, 36, and 39 psu. The optimal salinity was determined to be 36 psu, with a survival rate of $70.0{\pm}2.0%$. Transportation experiments at 36 psu were conducted at water temperatures of 21, 24, 27, and $30^{\circ}C$, different developmental stages such as morula, 5-myomere, and tail beating for hatching and survival rates. The optimal water temperature and developmental stage for transporatation were $30^{\circ}C$ and tail beating stage and those hatching rates were $50.6{\pm}1.9%$ and $86.3{\pm}1.3%$, respectively. At $21^{\circ}C$, the survival rate by transportation water temperature was highest ($73.1{\pm}10.6%$), but the hatching rate ($17.1{\pm}3.1%$) was lowest. Therefore, the hybrid grouper fertilized eggs (E. fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) can be most efficiently produced under long-distance transportation conditions during the tail beating stage and at a water temperature of $30^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.948-953
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• 2021

To find the optimal eggs to larvae transforming temperature of walleye pollock Theragra chalcogramma, we investigated their hatching pattern, mortality, and larval deformities. Results showed that the hatching quality decreased as the water temperature increased and dropped sharply above 13℃. The highest hatching rate was achieved at 7℃, whereas the lowest was at 15℃. Dead eggs were not observed at 7℃; however, dead egg ratios were significantly high at 4.5℃ and above 13℃ (P<0.05). Mortality of larvae after hatching was not observed at 4.5℃, but was significantly high above 13℃. The DNA content of the larvae did not show any significant difference at all water temperatures; however, RNA content was the highest at 7℃ and was significantly low above 11℃. In addition, RNA/DNA ratio was the highest at 7℃. Larval deformities after hatching were low at 7-11℃ and higher at higher or lower water temperature. Therefore, the hatching index and larval health index of Walleye pollock eggs in this study show that 7℃ to 11℃ seems to be the optimal transforming water temperature range.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.625-633
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• 2020

The effects of temperature and salinity on egg development and settlement of the ascidian Herdmania momus were investigated. Adult specimens were collected from the Dodu Yacht facility in Jeju Island, Korea(33°30'30.54"N, 126°27'55.46"E) in August 2018. Egg development and larval settlement were observed and recorded at 8 h intervals using a stereomicroscope, under nine temperature (10, 13, 16, 19, 22, 25, 28, 31, and 34℃), and four salinity regimens (28, 30, 32, and 34 psu). The highest hatching rate (82.8±7%) was observed at 32 psu and 25℃ and the lowest hatching rate (1.0±2%) was at 34 psu and 13℃. The developmental rate (0.222±0.0994) was highest at 28 psu and 28℃, and lowest (0.016±0.008) at 30 psu and 13℃. The highest settlement success rate (77.1±5%) was at 32psu and 25℃ and the lowest(0.1±1.0%) was at 30psu, and 13℃. The rate of settlement(0.080±0.000) was highest at 28psu and 28℃, and lowest(0.013±0.000) at 30psu and 13℃. Both hatching and settlement success rates increased as temperature increased and tended to decrease beyond an optimal temperature range. Herdmania momus preferred 30-34 psu salinity and 22-25℃ temperature. This study provides baseline information about the life history of H. momus, and important data to control the damage caused by the increase in number and distribution of this invasive ascidian.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.3
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• pp.152-156
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• 2016

Objective: We studied the effect of the site of laser zona opening on the complete hatching of mouse blastocysts and the cell numbers of the completely hatched blastocysts. Methods: Mouse blastocysts were randomly allocated to the inner cell mass (ICM) group (zona opening performed at the site of the ICM, n=125), the trophectoderm (TE) group (zona opening performed opposite to the ICM, n=125) and the control group (no zona opening, n=125). Results: The rate of complete hatching of the blastocysts was not significantly different in the ICM and the TE group (84.8% vs 80.8%, respectively; p=0.402), but was significantly lower in the control group (51.2%, p<0.001). The cell numbers in the completely hatched blastocysts were comparable in the control group, the ICM group, and the TE group ($69{\pm}19.3$, $74{\pm}15.7$, and $71{\pm}16.8$, respectively; p=0.680). Conclusion: These findings indicate that the site of laser zona opening did not influence the rate of complete hatching of mouse blastocysts or their cell numbers.

• Korean journal of applied entomology
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• v.29 no.1
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• pp.20-24
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• 1990

Studies were carried out to investigate the overwintering densities of spider mites, hatching rate and time of P. ulmi eggs, and seasonal occurrences of spider mites (P. ulmi and T. urticae) in apple orchards of Kyungpook province from 1987 to 1989. Overwintering density of P. ulmi eggs was higher in Kunwi, Andong, Chilgok but lower in Kyungju. Overovintering densities of T. urticae were high in all the regions. With the hatching time and rate for P. ulmi eggs, the first hatching ate was April 14, and the last was May 3, and the average hatching rate was 89.3%. The density of P. ulmi was high from early May to middle July and T. urticae begin to increase rapidly from middle June and then was continuously high upto fruit harvesting time.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.32-38
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• 2009

The hatching rate of the eggs of Triops longicaudatus (LeConte), an endangered tadpole shrimp species in Korea, was experimented in different levels of temperature (10, 15, 20, 25, 30, 35, 40, 45, and $50^{\circ}C$) under 24 L photoperiod conditions in incubator. Eggs of T. longicaudatus in this study were obtained from the adults collected from Andong-si, Gyeongsangbuk-do, Korea, in July 2006. The highest hatching rate was the 80.0 (${\pm}9.43$)% in average at $35^{\circ}C$. The thermal threshold for hatching was derived at $6.66^{\circ}C$. However, eggs were not hatched both at $10^{\circ}C$ and at $50^{\circ}C$ during the experimental period.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.158-166
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• 2009

To obtain the fundamental data for the mass seedling production of grunt, Hapalogenys nitens, we investigated the influence of salinity and cold water temperature on hatching and survival of eggs and growth and survival of larvae and fry. In regards to salinity, we surveyed the hatching rate and floating rate of fertilized eggs, the floating rate and survival rate of hatching larvae, and the survival and growth of fry. In respect to cold temperature, we investigated the influence of degree of daily temperature decrease, acute temperature shock, and slow temperature decreases on the survival, feeding and swimming activities of fry. In the salinity experiment, the hatching and floating rates of fertilized eggs, and the floating and survival rates of hatching larvae, were shown to be higher in seawater than in brackish water. Growth and survival of larvae and fry were not different between seawater (25~32 psu) and brackish water (5~20 psu), but were significantly lower in freshwater. In the cold-temperature test, three tests showed that rearing of fry in cold water and acutely decreasing water temperature to less than $10^{\circ}C$ reduced the survival, feeding and swimming activities of the fry. Therefore, we concluded that low salinity (less than 32 psu) could reduce the hatching rate and survival of eggs, but the growth and survival of fry were not influenced by salinity, and cold water (less than $10^{\circ}C$) decreased metabolism of grunt. During winter, we found a low-temperature limit at $8^{\circ}C$.

• 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 $25^{\circ}C$.

• Clinical and Experimental Reproductive Medicine
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• v.41 no.2
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• pp.68-74
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• 2014

Objective: In search of an ideal method of assisted hatching (AH), we compared the effects of conventional micropipette-AH and laser-AH on the blastocyst formation rate (BFR) and blastocyst cell numbers. Methods: Four-to five-week-old ICR female mice were paired with male mice after superovulation using Pregnant mare's serum gonadotropin (PMSG) and hCG. The two-cell embryos were flushed from the oviducts of female mice. The retrieved two-cell embryos underwent one of five AH procedures: single mechanical assisted hatching (sMAH); cross mechanical assisted hatching (cMAH); single laser assisted hatching (sLAH); quarter laser assisted hatching (qLAH); and quarter laser zona thinning assisted hatching (qLZT-AH). After 72 hours incubation, double immunofluorescence staining was performed. Results: Following a 72 hours incubation, a higher hatching BFR was observed in the control, sMAH, cMAH, and sLAH groups, compared to those in the qLAH and qLZT-AH groups (p<0.05). The hatched BFR was significantly higher in the qLAH and qLZT-AH groups than in the others (p<0.05 for each group). The inner cell mass (ICM) was higher in the control and sMAH group (p<0.05). The trophectoderm cell number was higher in the cMAH and qLAH groups (p<0.05). Conclusion: Our results showed that the hatched BFR was higher in groups exposed the the qLAH and qLZT-AH methods compared to groups exposed to other AH methods. In the qLAH group, although the total cell number was significantly higher than in controls, the ICM ratio was significantly lower in than controls.

• Development and Reproduction
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• v.2 no.2
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• pp.179-187
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• 1998

The effects of prostaglandins in hatching and implantation have been studied but the results were various, and those are not well known by the embryonic stage. The present study examined the effects of prostaglandin $E_2$(PG $E_2$) and prostaglandin $F_2$$_{\alpha}$ (PG $F_2$$_{\alpha}$) on the expansion and hatching of mouse embryos by embryonic stage. Also we tried to measure the concentration of prostaglandins of morula, expanded, and hatching embryos. In early morula stage embryos, high concentration of PG $E_2$(>100$\mu$M) showed cytotoxicity but PG $F_2$$_{\alpha}$ did not. The hatching was inhibited all groups but not gave negative effects on expansion. In 84 hr and 96 hr stage embryos, the hatching rate was decreased at all treatment groups but not inhibited the expansion. When combine prostaglandin with indomethacin, the hatching rate was increased significantly compared to the prostaglandin-treated groups, and as lower and lower the PG $E_2$ concentration, the hatching rate increased to the control level. The embryonic synthesis of PG $E_2$ increased dramatically but that of PG $F_2$$_{\alpha}$ increased gradually. PG $E_2$ showed cytotoxicity at early stage embryos much than late stage embryos, but PG $F_2$$_{\alpha}$ did not. Hatching was inhibited by the high PG $F_2$$_{\alpha}$ concentration. It is suggested that the inhibition of hatching might be at resulted from cytotoxicity of PG $E_2$ on embryo. However, it is thought that the mechanisms of inhibition of hatching are different between PG $E_2$ and PG $F_2$$_{\alpha}$. In conclusion, it can be suggested that PG $E_2$ and PG $F_2$$_{\alpha}$ concerned with the expansion and hatching, and their effects on hatching were different by the embryonic stage.$/ concerned with the expansion and hatching, and their effects on hatching were different by the embryonic stage.