• Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.77-81
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• 2012

We assessed the toxicity of cryoprotectant agents (CPAs) to gametophytic thalli of red alga Porphyra yezoensis at room temperature. The CPAs used were: dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol (GC), 1,2-butanediol (1,2-BD), 1,3-butanediol (1,3-BD), 2,3-butanediol (2,3-BD), 1,3-propanediol (1,3-PD) and propylene glycol (PG). CPA concentrations of 10, 15, 20, 25, 30, 35, 40, 45, and 50% were employed with 30 or 60 s immersion. The toxicity of the eight CPAs to gametophytic thalli of P. yezoensis was in the order: 1,3-BD < DMSO ${\approx}$ 2,3-BD ${\approx}$ PG ${\approx}$ EG < GC < 1,3-PD ${\approx}$ 1,2-BD. All thalli were more sensitive to high CPA concentrations, and most (>75%) thalli survived exposure to 10-25% CPA for 60 s. These data will facilitate selection of the optimal cryoprotectant concentration for cryopreservation of P. yezoensis thalli.

• Food Science and Preservation
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• v.22 no.2
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• pp.167-173
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• 2015

This study was conducted to evaluate effect of adding cryoprotectant agents on the growth of lactic acid bacteria during storage of powdered Kimchi. Powdered Kimchi was prepared by adding 1.5% cryoprotectant (glucose, maltose, lactose, and sucrose) and freeze-dried. For the preparation of micro-sized particle of Kimchi powder, the freeze-dried Kimchi was powered at 14,000 rpm for 2 min. The survival ratio of lactic acid bacteria in the powdered Kimchi was monitored during storage period of 4 months at -20, 0, 4, and $25^{\circ}C$ after the capsulation of the powedered Kimchi. The number of lactic acid bacteria in the powdered Kimchi capsule was the greatest stored at $-20^{\circ}C$, and the addition of glucose in cryoprotectant showed higher survival rate of lactic acid bacteria than that of control. More than $10^7CFU/g$ of lactic acid bacteria were survived in the powdered Kimchi stored at 0 and $4^{\circ}C$. However, the lactic acid bacteria were not detected in the powdered Kimchi stored at $25^{\circ}C$. As a results, the addition of cryoprotectant agents in the manufacturing process improved the survival rate of lactic acid bacteria in powered Kimchi products with accompanying with a cold-chain system for the distributon of powdered Kimchi products.

• The Korean Journal of Food And Nutrition
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• v.14 no.5
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• pp.441-445
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• 2001

For the developement of probiotics, three strains haying psychorophilic and salt tolerant characteristics were isolated from Kimchi. Among the isolated strains, MGl9, MG89 and MG208 were identified as Lactobacillus brevis, Enterococcus faecium and Lactobacillus plantarum, respectively. The relationship between cryoprotectant and the viability of freeze dried strains has been studied. The most effective cryoprotectant for MGl9 was found to be 10% skim milk contained 1% soluble starch haying the survival rate of 71.4%. In MG89, 10% skim milk contained 1% sucrose and 10% skim milk contained l% fructose in MG208 were showed effective cryoprotectant having the survival rate 68.9% and 64.7%. respectively These results suggest that these isolated strains can play an important role as probiotics in aquaculture.

• Korean Journal of Animal Reproduction
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• v.21 no.2
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• pp.95-102
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• 1997

The studies on the carried out to investigate the effective concentration of cryoprotectant agents and sucrose by one-step straw method of bovine embryos. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/ml PMSG(Sigma, USA), 10 IU/ml hCG(Sigma, USA), 1$\mu\textrm{g}$/ml $\beta$-estradiol(Sigma, USA) and 10% FCS for 24~48 hrs in incubator with 5% CO2 in air at 38.5$^{\circ}C$ and then matured oocytes were again cultured for 12~18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and various concentrations of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival and in vitro developmental rate was defined as devellpmental rate on in vitro culture or FDA-test. The results are smmarized as followes : 1. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was attained 2.0M glycerol, 2.0M DMSO, 1M or 2.0M propanediol. 2. The high in vitro developmental rates of bovine frozen embryos after rapidly thawed in freezing medium was obtained single cryoprotectant(6.7~17.4%) than mixed cryoprotectants(6.7~16.7%). 3. In vitro developmental rate of bovine embryos after rapid frozen-thawing in the freezing medium added 0.25M and 0.50M sucrose were higher cleavage rate than those of sucrose concentration of 0.75M and 1.00M. 4. The freezing methods on in vitro developemental rates of bovine embryos was attained slow freezing method(9.70~15.6%) higher than rapid freezing method(9.4~13.3%).

• Clinical and Experimental Reproductive Medicine
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• v.18 no.1
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• pp.81-87
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• 1991

There studies were carried for evaluation of the efficiency of freezing of hamster oocytes for use in a human sperm penetration assay. The hamster oocytes fully equilibrated in various cryoprotectant agents and inseminated with human sperm. After insemination with hamster oocytes, there was no difference in penetrated rates. Cumulus free oocytes equilibrated in 1.5M various cryoprotective agents and slowely cooled to temperature $-30^{\circ}C$ before rapid cooling and storage in nitrozen tank. After rapid thawing, survival rates of frozen oocytes according to cryo-protective agents were examined and the human sperm penetration assay with zona free hamster oocytes was conducted. 1. Survival rates of oocytes after cryoprotectants exposure have no significant difference (range 88-91%) and peneration rate was 51.1%. 2. Recovery and survival rate of frozen-thawed oocytes were 85.1 and 66.8%. There was no significant difference on cryoprotective agents. 3. Penetration rates of the frozen-thawed and intact oocytes were 69.0 and 77.0%, respectively. 4. Hamster oocytes cryopreservation provides a convenient way of supplying and trans-porting hamster oocytes for the assessment of the fertilizing potential of human spermatozoa.

• Journal of Marine Life Science
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• v.1 no.1
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• pp.70-78
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• 2016

Microalgae are of significant importance for future biotechnological applications. Many microalgae banks or laboratories attempt to maintain various microalgae for further research purposes. Cryopreservation has been preferred to reduce a labor-intensive and costly routine sub-culturing. Cryopreservation can also diminish the genetic drift risk. However, cryopreservation as a long term storage of microalgae method are still in developing progress because it cannot be generalized for all microalgae. Microalgae types, cryoprotectant agents (CPAs) types, freezing and thawing methods are the most important factors that should be considered for cryopreservation. In this short review the basic principles and the current advanced of microalgae cryopreservation methods are discussed with a suggested starting parameters for microalgae cryopreservation.

• Progress in Superconductivity and Cryogenics
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• v.21 no.1
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• pp.40-44
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• 2019

This study investigates mixtures of water and cryoprotectant agents (CPAs) to store high-grade cold energy. Although water is an ideal material for a cold thermal storage (CTS) due to its high specific heat, undesirable volume expansion may cause structural stresses during freezing. The volume expansion can be alleviated by adding the CPAs to water. However, the CPA aqueous solutions not only have different thermal properties but also transit to amorphous state different from pure water. Therefore, these characteristics should be considered when using them as material of the CTS. In experiments, glycerol and dimethyl sulfoxide (DMSO) are selected as the candidate CPA. The volume expansion of the solution is measured by an in-situ strain gauge in low temperature region. The specific heat capacity of the solution is also measured by differential scanning calorimetry (DSC). Both the amount of volume expansion and the specific heat capacity of the CPA aqueous solution decrease in the case of higher concentration of CPA. These characteristics should be contemplated to select optimal aqueous solution for CTS for liquid air energy storage system (LAES). The CPA solutions have advantages of having wide temperature range to utilize the latent heat of water and higher sensible heat of the CPA. The CPA solutions which can satisfy the allowable stress of the structure are determined. Consequently, among the CPA solutions investigated, DMSO 20% w/w solution is the most suitable for the CTS.

• Korean Journal of Poultry Science
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• v.41 no.4
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• pp.261-270
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• 2014

This study was conducted to establish the method for preserving chicken primordial germ cells (PGCs) that enables long-term storage in liquid nitrogen ($LN_2$) for developmental engineering or preservation of species. The purpose of this study is to clarify the effects of simple freeze-thaw treatment on viability of PGCs in chickens and to the optimal protocol for PGCs freezing. PGCs obtained from the germinal gonade of an early embryos of 5.5~6 day (stage 28) of Isa Brown, Korean Ogye (KO), White Leghorn and Commercial breeds, using the MACS method were suspended in a freezing medium containing a freezing and protecting agents (e.g. dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG)). The gonadal cells, including PGCs, were then frozen in 1 of the following cryoprotectant treatments : 2.5%, 5%, 10%, 15%, and 0% cryoprotectant (DMSO, EG, PG) as a control. Effects of exposure to simple freezing, with different concentrations of the cryoprotectant solution, were examined. After simple freezing, the viability of PGCs after freeze-thawing was significantly higher for Commercial breeds ($88.7{\pm}2.4%$) than KO ($85.1{\pm}0.4%$), Isa Brown ($84.6{\pm}0.2%$) and White Leghorn ($85.9{\pm}0.1%$) (p<0.05) using 10% EG cryoprotectant. Therefore, these systems may contribute in the improvement of cryopreservation for a scarce species in birds preservation. This study established a method for preserving chicken PGCs that enables systematic storage and labeling of cryopreserved PGCs in liquid ($LN_2$) at a germplasm repository and ease of entry into a database.

• Reproductive and Developmental Biology
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• v.39 no.3
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• pp.77-81
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• 2015

This study was carried out to evaluate the effects of embryonic stage and toxicities of cryoprotectant on the rates of survival and development of the cryopreserved mouse early embryo and finally to establish the cryopreservation method of surplus embryos obtained during assisted reproductive technology. Toxicities of two cryoprotectants, dimethyl sulfoxide (DMSO) and ethylene glycol (EG) were investigated using a murine embryo model. Female F-1 mice were stimulated with gonadotropin, induced ovulation with hCG and mated. Two cell embryos were collected and cultured after exposure to either DMSO or EG. Embryo development was evaluated up to the blastocyst stage. The total cell count of blastocysts that were treated with DMSO ($68.1{\pm}24.1$) at the 2-cell stage was significantly lower than that were treated with EG ($81.2{\pm}27.0$) or the control ($99.0{\pm}18.3$) (p<0.001). On comparison of two cryoprotectant treated groups, the DMSO treated group showed a decreased cell count compared with the EG treated group (p<0.05). Both DMSO ($15.4{\pm}1.5$) and EG ($10.2{\pm}1.4$) treated groups showed higher apoptosis rates of cells in the blastocyst compared with the control ($6.1{\pm}0.9$, p<0.0001). In addition, the DMSO treated group showed more apoptotic cells than the EG treated group (p<0.001). The potential toxicity of cryoprotectants was uncovered by prolonged exposure of murine embryos to either DMSO or EG at room temperature. When comparing two cryoprotective agents, EG appeared to be less toxic than DMSO at least in a murine embryo model.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.3
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• pp.228-238
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• 2005

Purpose: Several cryoprotectants are in use to help the survival of cells during cryopreservation of bone in maxillofacial region. Among them, $Me_2SO$(dimethyl sulfoxide), EG(ethylene glycol), sucrose were used for experimentally created defects with accompanying cryopreserved bone graft in the rabbit model. The aim of this study is to analyze the effect of above mentioned agents on bone formation using histologic and histomorphometrical methods, thus to provide experimental support for clinical application of these agents. Materials and methods: Nine rabbits were used as experimental animals. Surgical defects were created on the distal femoral heads and mesial tibial heads of each animal using trephine drill(5mm diameter and 5mm length). The harvested bones were cryopreserved in $-80^{\circ}C$ refrigerator for one week. The defects were filled with cryopreserved bone with cryoprotectants as experimental groups and cryopreserved bone without cryoprotectant as control. Then, the animals were sacrificed at 1, 2, and 3 weeks after surgery. With Goldner's modified Masson trichrome staining and semiautomatic image analysis system, we observed the change of the cells and bone formation. Results: After bone graft, bone formation and active remodeling process were examined in all experimental groups and the control. But the intensity of such activities of the control were somewhat weaker than that of the experiments. Especially $Me_2SO$+sucrose group was the best in bone formation and bone remodeling. $Me_2SO$ group was more than that of EG group in bone fomation. Sucrose seems to be helpful in survival of the bone cell. Histologic findings showed superior bony quantity and quality in experimental groups than that in control. Conclusions: The data from this study provides the basis for future studies for evaluating the effect of cryoprotectants in the cryopreservation of bone and clinical study for predictable use of these agents.