• Journal of Embryo Transfer
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• v.6 no.2
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• pp.1-17
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• 1991

It is widely recognized that the embryonic or fetal loss after breeding is common in the cattle and that it is an important factor affecting reproductive efficiency. The causes of this loss have been subject of extensive researches and the results indicate that the embryonic mortality may he primary factor responsible for low pregnancy rates in non-embryo transfer bovine populations as well as embryo transfer programs. However, it's causes are still not clearly understood. The embryonic mortality or pregnancy rate has been influenced by various embryonic and maternal effects related to genetic and environmental factors. The timing and extent of embryonic mortality vanes greatly according to authors and estimating methods, because it is difficult to make direct measurements. The major important factors that may influence the embryonic losses or pregnancy rates after embryo transfer can be summeirized. 1.When an embryo is transferred to unmated recipients, the contralateral transfer to corpus luteum results in a lower survival rate than ipsilateral deposition. When the embryos are transferred for the production of twin calves, their survivals and twin pregnancies have quite inconsistent according to the transfer methods either to the unmated-synchronized or already mated recipients and more works are needed to accurrately clarify the previous results. 2.Although embryos can be cultured in vitro some hours without the great declines in pregnancy rates, the rates differ markedly among culture times and media but may be improved by co-transfer systems. 3.Embryo developmental stages and quality grades clearly affect the survival rate following freezing and the pregnancy rate after transfer and the selection of embryos without chromosome abnormalities and of high fertile semen may also be considered to increase the pregnancy rates. 4.Many researches have attempted to relate the plasma progesterone levels to pregnancy rates and others have done either direct progesterone supplementation or luteal stimulation by hCG treatment in order to increase the pregnancy rates. However, these effects on pregnancy rates are inconsistent and also contradictory. 5.The asynchrony between donors or embryos and recipients may he a major cause of embryo death and low pregnancy rate and the sensitivity to uterine asynchyony differs in according to the quality and stages of embryos. 6.The extremes of poor or over nutrition during early pregnancy in the recipients are detrimental to the survival of embryos and the good body condition is required to prevent a reduejion of pregnancy rates. The uterine pathogens in embryonic mortality or fertility have been questioned but the infection of C.pyogenes and Campylobacter fetus is still important pathogens. 7.The heat stress during early pregnancy may reduce conceptus weight and possibly increase the embryonic mortality.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.193-199
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• 2021

Solenopsis japonica, which is belonging to Formicidae in Hymenoptera, is a native ant species in Korea. However, it had not been studied for cold hardiness of S. japonica to understand on its overwintering mechanisms in field so far. Cold tolerance on developmental stages was measured at different cold temperature with various exposure times. Workers showed more survival at 5℃ and 10℃ compared with other stages and elevated cold tolerance when workers were exposed at 15℃ for more than 12h incubation as a rapid cold hardening (RCH) condition. RCH treatment not only increased survival of workers at cold temperatures, but also decreased supercooling point (SCP) and freezing point (FP). RCH group increased the survival rate by 44% at 10℃ compared with Non-RCH group. SCP and FP were depressed from -10.0 to -14.2℃ and from -11.3 to -15.3℃, respectively, after RCH treatment. Cold temperature increased expression level of cold- and stress-related genes such as glycerol kinase and heat shock protein. These results indicate unacclimated cold tolerance of S. japonica and its acclimation to low temperature by RCH.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.78-78
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• 2002

The role of heat shock proteins in shielding organism from environmental stress is illustrated by the large-scale synthesis of these protein by the organism studied to date. However, recent evidence also suggests an important role for heat shock protein in fertilization and early development of mammalian embryos. Effects of elevated in vitro temperature on in vitro produced bovine embryos were analysed in order to determine its impact on the expression of heat shock protein 70 (HSP70) by control and frozen-thawed after in vitro fertilization (IVF) or nuclear transfer (NT). The objective of this study was to assess the developmental potential in vitro produced embryos with using of the various containers and examined expression and localization of heat shock protein 70 after it's frozen -thawed. For the vitrification, in vitro produced embryos at 2 cell, 8 cell and blastocysts stage after IVF and NT were exposed the ethylene glycol 5.5 M freezing solution (EG 5.5) for 30 sec, loaded on each containers such EM grid, straw and cryo-loop and then immediately plunged into liquid nitrogen. Thawed embryos were serially diluted in sucrose solution, each for 1 min, and cultured in CRI-aa medium. Survival rates of the vitrification production were assessed by re-expanded, hatched blastocysts. There were no differences in the survival rates of IVF using EM grid, cryo-loop. However, survival rates by straw were relatively lower than other containers. Only, nuclear transferred embryos survived by using cryo-loop. After IVF or NT, in vitro matured bovine embryos 2 cell, 8 cell and blastocysts subjected to control and thawed conditions were analysed by semiquantitive reverse transcription polymerase chain reaction methods for hsp 70 mRNA expression. Results revealed the expression of hsp 70 mRNA were higher thawed embryos than control embryos. Immunocytochemistry used to localization the hsp70 protein in embryos. Two, 8-cell embryos derived under control condition was evenly distributed in the cytoplasm but appeared as aggregates in some embryos exposed frozen-thawed. However, under control condition, blastocysts displayed aggregate signal while Hsp70 in frozen-thawed blastocysts appeared to be more uniform in distribution.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.173-179
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• 2012

The experiments, which analyze the injury symptoms and diagnose growth conditions utilizing IRVT and analyzing each parts of H. helix L., had been held under a low temperature. Greenhouse and outdoor growing Genus hedera had been prepared and compared with each Genus hedera's peak and bottom leaves' surface temperature under the experimental categories $-6^{\circ}C$ and $-12^{\circ}C$. As results, analyzing the surface thermal property of peak part leaves' of outdoor growing Genus hedera, at experimental categories $-6^{\circ}C$, $-12^{\circ}C$ were ranged from $-2^{\circ}C{\sim}-7^{\circ}C$ and $-2^{\circ}C{\sim}-15^{\circ}C$. On the other hand, the surface thermal property of bottom part leaves at experimental categories $-6^{\circ}C$, $-12^{\circ}C$ were ranged $-2^{\circ}C{\sim}-11^{\circ}C$ and $-1^{\circ}C{\sim}-12^{\circ}C$. It appears that the thermal properties of leaves' surface on $-6^{\circ}C$ peaks and $-12^{\circ}C$ bottoms were more broadband than bottoms and peaks. It means that the peaks were more sensitive than bottoms, as like $-2^{\circ}C{\sim}-15^{\circ}C$, $-1{\sim}-12^{\circ}C$. Moreover, as similar results had seen to leaves surface temperature added to cold wind conditions. How the cold wind damaged the outdoor growing Genus hedera, analyzed the surface thermal property by IRVT data under $0^{\circ}C$, $-2^{\circ}C$, $-4^{\circ}C$ condition, it resulted to $-6.2^{\circ}C$, $-6.8^{\circ}C$, $-7.5^{\circ}C$. It appeared more $3.5{\sim}6.2^{\circ}C$ low temperature than experimental setting point. In addition, each parts thurmal property of peaks and bottoms was not similar, it referred to each parts' sensitivities of low temperature were different on the peak and bottom leaves surface temperature.