• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.220-228
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• 2008

In this study the aerodynamic characteristics of a canard-controlled missile with freely spinning tailfins were investigated by using a semi-empirical method and a CFD code. The mean aerodynamic coefficients for the rolling and roll damping moments were first calculated and then used to predict the roll-rate of freely spinning tailfins. The calculation of roll-rate in the CFD code was carried out by combining a Chimera overset grid system and 6-DOF analysis module. The predicted roll-rate was in good agreement with the experimental data for the roll and yaw canard control inputs. It was also shown that the results are in good agreement with the prediction by a CFD code. This indicates that the semi-empirical method can be used to predict the roll-rate of a canard-controlled missile with freely spinning tailfins.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.121-121
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• 2003

The standard protocol for the production of transgenic mouse from ES-injected embryo has to process via chimera producing and several times breeding steps, In contrast, tetraploid-ES cell complementation method allows the immediate generation of targeted murine mutants from genetically modified ES cell clones. The advantage of this advanced technique is a simple and efficient without chimeric intermediates. Recently, this method has been significantly improved through the discovery that ES cells derived from hybrid strains support the development of viable ES mice more efficiently than inbred ES cells do. Therefore, the objective of this study was to generate transgenic mice overexpressing human resistin gene by using tetrapioid-ES cell complementation method. Human resistin gene was amplified from human fetal liver cDNA library by PCR and cloned into pCR 2.1 TOPO T-vector and constructed in pCMV-Tag4C vector. Human resistin mammalian expression plasmid was transfected into D3-GL ES cells by lipofectamine 2000, and then after 8~10 days of transfection, the human resistin-expressing cells were selected with G418. In order to produce tetraploid embryos, blastomeres of diploid embryos at the two-cell stage were fused with two times of electric pulse using 60 V 30 $\mu$sec. (fusion rate : 93.5%) and cultured upto the blastocyst stage (development rate : 94.6%). The 15~20 previously G418-selected ES cells were injected into tetraploid blastocysts, and then transferred into the uterus of E2.5d pseudopregnant recipient mice. To investigate the gestation progress, two El9.5d fetus were recovered by Casarean section and one fetus was confirmed to contain human resistin gene by genomic DNA-PCR. Therefore, this finding demonstrates that tetraploid-ES mouse technology can be considered as a useful tool to produce transgenic mouse for the rapid analysis of gene function in vivo.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2005.11a
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• pp.68-69
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• 2005

To identify germline chimeric chicken using germ cell transplantation method, the testcross, spends much time, labor and cost to perform, is the only way for distinguishing germline chimeric chicken from normal one And to enhance the method, development of breed-specific molecular markers have been needed. We have just identified breed-specific sequence polymorphisms among Barred Plymouth rock, Korean Ogol Chicken and White Leghorn in PMEL17 and MC1R gene the loci of which are identical to dominant white and extended black loci. These sequence polymorphism will be very useful for screening germline chimera.

• Genomics & Informatics
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• v.21 no.3
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• pp.40.1-40.11
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• 2023

Microbial community profiling using 16S rRNA amplicon sequencing allows for taxonomic characterization of diverse microorganisms. While amplicon sequence variant (ASV) methods are increasingly favored for their fine-grained resolution of sequence variants, they often discard substantial portions of sequencing reads during quality control, particularly in datasets with large number samples. We present a streamlined pipeline that integrates FastP for read trimming, HmmUFOtu for operational taxonomic units (OTU) clustering, Vsearch for chimera checking, and Kraken2 for taxonomic assignment. To assess the pipeline's performance, we reprocessed two published stool datasets of normal Korean populations: one with 890 and the other with 1,462 independent samples. In the first dataset, HmmUFOtu retained 93.2% of over 104 million read pairs after quality trimming, discarding chimeric or unclassifiable reads, while DADA2, a commonly used ASV method, retained only 44.6% of the reads. Nonetheless, both methods yielded qualitatively similar β-diversity plots. For the second dataset, HmmUFOtu retained 89.2% of read pairs, while DADA2 retained a mere 18.4% of the reads. HmmUFOtu, being a closed-reference clustering method, facilitates merging separately processed datasets, with shared OTUs between the two datasets exhibiting a correlation coefficient of 0.92 in total abundance (log scale). While the first two dimensions of the β-diversity plot exhibited a cohesive mixture of the two datasets, the third dimension revealed the presence of a batch effect. Our comparative evaluation of ASV and OTU methods within this streamlined pipeline provides valuable insights into their performance when processing large-scale microbial 16S rRNA amplicon sequencing data. The strengths of HmmUFOtu and its potential for dataset merging are highlighted.

• Journal of Animal Science and Technology
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• v.50 no.1
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• pp.9-18
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• 2008

Species-specific polymorphisms in chicken, pheasant, turkey, and quail were identified by cloning and sequencing of the immunoglobulin constant domain (IgLC). A set of species-specific primers were then designed on the basis of polymorphisms in the IgLC between species, as well as two additional sets of primers for the cytochrome b and tapasin genes, for the purpose of species identification. Together, the primers successfully distinguished specific species from chicken by species-specific PCR. This simple but unambiguous method may be used to screen avian inter-species germline chimeras, which are valuable models for the conservation of endangered species.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.55-60
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• 2018

Microbial communities of four commercial Korean nuruks were analyzed by the 454 pyrosequencing method to correlate different characteristics of rice wine fermentation. The total and average sequencing reads of fungi in the four nuruks were 14,800 and 3,494, respectively. At the phylum level, Ascomycota was dominant in three nuruks, namely, SH, SS, and JJ, while Zygomycota was dominant in SJ. Saccharomycopsis was dominant in nuruks subjected to longer fermentation periods, such as SH and SS. The total and average sequence reads for bacteria were 31,485 and 7,871, respectively. Bacteria belonging to the phylum Firmicutes were dominant in all samples. SH showed several genera of lactic acid bacteria, such as Lactobacillus, Leuconostoc, Pediococcus, and other minor bacteria. Staphylococcus and Bacillus were the dominant bacteria in JJ and SJ, respectively.

• Biomedical Science Letters
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• v.10 no.4
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• pp.391-395
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• 2004

The demand for the production of gene-defective mice from embryonic stem (ES) cells is increasing to clarify decisive gene function in vivo. Although blastocyst injection is widely used to generate ES cell-mediated knockout mice, coculture method has been alternatively used because of several advantages, such as low cost and simple procedure. Thus, this experiment was designed to demonstrate the feasibility of the coculture method using J1 ES cells, which are known to be efficient for blastocyst injection. Eight-cell embryos were harvested from 2.5 days post-coitum (dpc), denuded with acid tyrode's solution, and transferred onto trypsinized J1 ES cells. Aggregation was carried out following two typical methods, which are simple coculture method and aggregation in groove prepared by aggregation needle. Successfully aggregated-embryos were developed to blastocysts for 24 h and transferred into uterus of pseudo-pregnant foster mother. Chimeric offspring was judged by coat pigmentation. In this study, we could obtain chimeric mice from all the two aggregation methods, but the chimera production efficiencies in coculture using groove were three times higher at least than those in the other group. In conclusion, these observations suggest that coculture method should be available for production of knockout mice from J1 ES cells. Presently, the germ-line transmission rates of the chimeras produced from the two methods are under investigation.

• Korean Journal of Poultry Science
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• v.28 no.2
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• pp.135-142
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• 2001

A novel sterategy has been established to determine the origin of the Primordial Germ Cells (PGCs) in avian embryos directly and the developmental fate of the PGCs for the application to Poultry biotechnology. Cells were removed from 1) the centre of area pellucida, 2) the outer of area pellucida and 3) the area opaca of the stage X blastoderm (Eyal-Giladi & Kochav, 1976). When the cells were removed from the centre of area pellucida, the mean number of circulating PGCs in blood was significantly decreased in the embryo at stage 15 (Hamburger & Hamilton, 1951) as compared to intact embryos. When the cells were replenished with donor cells, no reduction in the PGCs number was observed. The removal of cells at the outer of area pellucida or at the area opaca had no effect on the number of PGCs. In case, another set of the manipulated embryos were cultured ex vivo to the hatching and reared to the sexual maturity, the absence of germ cells and degeneration of seminiferous tubules was observed in resulting chickens derived from the blastoderm in which the cells were removed from the centre of the area pellucida. It was concluded that the avian Primordial Germ cells are originated at the center of area pellucida. Developmental ability of the cells to differentiate into somatic cells and germ cells in chimeras were analyzed. Somatic chimerism was detected as black feather attributed from donor cells. Molecular identification by use of female - specific DNA was performed. It was confirmed that the donor cells could be differentiated into chimeric body and erythrocytes. Donor cells retained the ability to differentiate into germline in chimeric gonads. More than 70% of the generated chimeras transmitted donor derived gametes to their offspring indicating that the cells at the center of area pellucida had the high ability to differentiate into germ cells. A molecular technique to identify germline chimerism has been developed by use of gene scan analysis. Strain specific DNA fragments were amplified by the method. It would be greatly contributed for the detection of germline chimerism. Mixed- sex chimeras which contained both male and female cells were produced to investigate the developmental fate of male and female cells in ovary and testes. The sex combinations of donor and recipient of the resulting chimeras were following 4 pairs; (1) chimeras (ZZ/ZZ) produced by a male donor (ZZ) and a male recipient (ZZ), (2) chimeras (ZW/ZW) produced by a female donor (ZW) and a female recipient (ZW), (3) chimeras (ZZ/ZW) Produce by a male donor (ZZ) and a female recipient (ZW), (4) chimeras (ZW/ZZ) produced by a female donor (ZW) and a male recipient (ZZ). It was found that genetically male avian germ cells could differentiate into functional ova and that genetically female germ cells can differentiate into functional spermatozoa in the gonad of the mixed- sex chimeras. An ability for introduction of exogenous DNA into the PGCs from stage X blastoderms were analyzed. Two reporter genes, SV-$\beta$gal and RSV-GFP, were introduced into the PGCs. Expression of bacterial/gal was improved by complexing DNA with liposome detectedcc in 75% of embryos at 3 days embryos. At the embryos incubated for 1 day, expression of the GFP was observed all the embryos. At day 3 of incubation, GFP was detected in about 70% of the manipulated embryos. In case of GFP, expression of the transgene was detected in 30 %e of the manipulated embryos. These results suggested that the cells is one of the most promising vectors for transgenesis. The established strategy should be very powerfull for application to poultry biotechnology.

• Korean Journal of Poultry Science
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• v.40 no.3
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• pp.163-169
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• 2013

Cryopreservation of poultry semen has been reported, but preservation of female genetic material has not been possible because of the unique anatomical and physiological characteristics of the avian egg. Thus an alternative strategy for conservation of oviparous species of animals must be developed. Recent technological developments for producing germline chimeras by the transfer of primordial germ cells (PGCs) into recipient embryos has enabled the conservation and retrieval of chicken genetic resources in their complete form. In the present study, fertilized eggs were incubated for about 5.5 days to obtain embryos at stage 28. The whole embryo was collected from the germinal gonad using a fine glass micro pipette under a microscope. The PGCs were then purified using MACS method. Two commercially available cryoprotectants (A and B) were used to preserve the PGCs, and EG were used as a control. The average recovery rate of PGCs after thawing was 35.5% and 60.5% with the A and B treatments, respectively. There was no significant difference between B treatments and control, which showed an average recovery rate of 52.8%. However, the recovery rate obtained using A cryoprotectant (35.5%) was significantly lower than using treatment control and B. The average viability of the PGCs after thawing were 77.9% and 77.4% for cryoprotectants A and B, respectively, and the control were was 81.6%. There was no statistically significant difference between the two treatments and control. It was concluded that all of the available cryoprotectants examined in this study could be used for preservation of PGCs from embryos. Further experiments to produce germline chimera from PGCs preserved using this techniques are strongly recommended.