Biomedical subjects

Du-Hak Yoon

Publications and source records attributed to Du-Hak Yoon.

4 recordsLinked to original sources

PubMed2006

Growth hormone-releasing hormone (GHRH) polymorphisms associated with carcass traits of meat in Korean cattle.

BACKGROUND: Cold carcass weight (CW) and longissimus muscle area (EMA) are the major quantitative traits in beef cattle. In this study, we found several polymorphisms of growth hormone-releasing hormone (GHRH) gene and examined the association of polymorphisms with carcass traits (CW and EMA) in Korean native cattle (Hanwoo). RESULTS: By direct DNA sequencing in 24 unrelated Korean cattle, we identified 12 single nucleotide polymorphisms within the 9 kb full gene region, including the 1.5 kb promoter region. Among them, six polymorphic sites were selected for genotyping in our beef cattle (n = 428) and five marker haplotypes (frequency > 0.1) were identified. Statistical analysis revealed that -4241A>T showed significant associations with CW and EMA. CONCLUSION: Our findings suggest that polymorphisms in GHRH might be one of the important genetic factors that influence carcass yield in beef cattle. Sequence variation/haplotype information identified in this study would provide valuable information for the production of a commercial line of beef cattle.

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PubMed2006

Confirming single nucleotide polymorphisms from expressed sequence tag datasets derived from three cattle cDNA libraries.

Using the Phred/Phrap/Polyphred/Consed pipeline established in the National Livestock Research Institute of Korea, we predicted candidate coding single nucleotide polymorphisms (cSNPs) from 7,600 expressed sequence tags (ESTs) derived from three cDNA libraries (liver, M. longissimus dorsi, and intermuscular fat) of Hanwoo (Korean native cattle) steers. From the 7,600 ESTs, 829 contigs comprising more than two EST reads were assembled using the Phrap assembler. Based on the contig analysis, 201 candidate cSNPs were identified in 129 contigs, in which transitions (69%) outnumbered transversions (31%). To verify whether the predicted cSNPs are real, 17 SNPs involved in lipid and energy metabolism were selected from the ESTs. Twelve of these were confirmed to be real while five were identified as artifacts, possibly due to expressed sequence tag sequence error. Further analysis of the 12 verified cSNPs was performed using the program BLASTX. Five were identified as nonsynonymous cSNPs, five were synonymous cSNPs, and two SNPs were located in 3'-UTRs. Our data indicated that a relatively high SNP prediction rate (71%) from a large EST database could produce abundant cSNPs rapidly, which can be used as valuable genetic markers in cattle.

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PubMed2004

Establishment of life-span extended bovine fibroblast cells carrying the characterization of primary cells.

Although primary bovine embryonic fibroblast (BEF) cells have previously been used as nucleus-donors for nuclear transfer (NT), it has now been proposed to use BEF cells to generate cloned cows that were genetically modified by transgenic or a knock-out system. A major limitation to gene targeting somatic cells, however, is the overall life-span of the cell. In this study, we first examined in vitro life-span of primary BEF cells. Primary BEF cells were found to be replicative senescent at passage 10th-12th, similar to primary murine embryonic fibroblast cells. To overcome this short in vitro life-span, we have optimized culture conditions to extend the life-span and determined growth characteristics of BEF cell lines. Two life-span extended BEF cell lines (designated CGFR -BO-1 and CGFR-BO-2) were shown to grow much faster than their parental primary counterparts. Both cell lines did not display any potential for abnormal growth such as foci formations in either soft-agar or confluent culture condition. In cloning experiments using these cell lines as a nuclear donor, the reconstructed karyoblasts underwent apoptosis, reprogramming and development in the blastocyst stage, at a similar frequency to those observed with parental as well as adult primary fibroblasts. Furthermore, these cell lines targeted with green fluorescence protein (GFP) were successfully transduced, selected and reprogrammed by NT to develop into a blastocyst stage with GFP expression. Our results suggested methods to extend life-span of donor cells with tremendous implications for the genetic engineering of bovine fibroblast cells.

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PubMed2004

Cellular characteristics of primary and immortal canine embryonic fibroblast cells.

Using normal canine embryonic fibroblasts (CaEF) that were shown to be senescent at passages 7th-9th, we established two spontaneously immortalized CaEF cell lines (designated CGFR-Ca-1 and -2) from normal senescent CaEF cells, and an immortal CaEF cell line by exogenous introduction of a catalytic telomerase subunit (designated CGFR-Ca-3). Immortal CGFR- Ca-1, -2 and -3 cell lines grew faster than primary CaEF counterpart in the presence of either 0.1% or 10% FBS. Cell cycle analysis demonstrated that all three immortal CaEF cell lines contained a significantly high proportion of S-phase cells compared to primary CaEF cells. CGFR-Ca-1 and -3 cell lines showed a loss of p53 mRNA and protein expression leading to inactivation of p53 regulatory function, while the CGFR-Ca-2 cell line was found to have the inactive mutant p53. Unlike the CGFR-Ca-3 cell line that down-regulated p16INK4a mRNA due to its promoter methylation but had an intact p16INK4a regulatory function, CGFR-Ca-1 and -2 cell lines expressed p16INK4a mRNA but had a functionally inactive p16INK4a regulatory pathway as judged by the lack of obvious differences in cell growth and phenotype when reconstituted with wild-type p16INK4a. All CGFR-Ca-1, -2 and -3 cell lines were shown to be untransformed but immortal as determined by anchorage-dependent assay, while these cell lines were fully transformed when overexpressed oncogenic H-rasG12V. Taken together, similar to the nature of murine embryo fibroblasts, the present study suggests that normal primary CaEF cells have relatively short in vitro lifespans and should be spontaneously immortalized at high frequency.

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