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손승렬,허승재 단국대학교 1998 論文集 Vol.33 No.-
Genetic transformation occurs naturally in a number of groups in bacteria, including Escherchia and Bacillus. The repair hypothesis proposes that a DNA fragment taken up by a cell is used as a template for recombinational repair in the recipient cell’s genome which is damaged. We developed an experimental system for studying DNA repair mechanisms through transformation after UV irradiation. The nature of transformed DNA are homologous chromosomal DNA. plasmid DNA and totally different salmon sperm DNA. Comparison of relative survival rates among control group and DNA transformation groups after UV irradiation revealed that a significantly higher survival rate was observed in chromosomal DNA group than in plasmid DNA group and in salmon sperm DNA group. In conclusion, the increased survival rate was caused by homologous DNA recombinational repair and we propose that this effect on increased survival rate might have been evolved to differentiate bacterial sexes, and then real sex in eukaryotes.
Role of the Promoter Region of a Chicken H3 Histone Gene in Its Cell Cycle Dependent Expression
Son, Seung-Yeol The Korea Science and Technology Center 1999 BMB Reports Vol.32 No.4
We fused the promoter region of an H3.2 chicken histone gene, whose expression is dependent on the cell cycle, to the 5' coding region of an H3.3 chicken histone gene, which is expressed constitutively at a low level throughout the cell cycle. This fusion gene showed a cell cycle-regulated pattern of expression, but in a different manner. The mRNA level of the fusion gene increased during the S phase of the cell cycle by about 3.7-fold at 6 h and 2.7-fold at 12 h after the serum stimulation. The mRNA level of the intact H3.2 gene, however, increased by an average of 3.6fold at 6 h and 8.7-fold at 12 h. This different expression pattern might be due to the differences in their 3' end region that is responsible for mRNA stability. The 3' end of the H3.2 mRNA contains a stem-loop structure, instead of a poly(A) tail present in the H3.3 mRNA. We also constructed a similar fusion gene using a H3.3 histone gene whose introns had been eliminated to rule out the possibility of involvement of the introns in cell cycle-regulated expression. The expression of this fusion gene was almost identical to the fusion gene made previously. These results indicate that the promoter region of the H3.2 gene is only partially responsible for its expression during the S phase of the cell cycle.
Role of the Promoter Region of a Chicken H3 Histone Gene in Its Cell Cycle Dependent Expression
Son, Seung-Yeol Korean Society for Biochemistry and Molecular Biol 1999 Journal of biochemistry and molecular biology Vol.32 No.4
We fused the promoter region of an H3.2 chicken histone gene, whose expression is dependent on the cell cycle, to the 5' coding region of an H3.3 chicken histone gene, which is expressed constitutively at a low level throughout the cell cycle. This fusion gene showed a cell cycle-regulated pattern of expression, but in a different manner. The mRNA level of the fusion gene increase during the S phase of the cell cycle by about 3.7-fold at 6 h and 2.7-fold at 12 h after the serum stimulation. The mRNA level of the intact H3.2 gene, however, increased by an average of 3.6-fold at 6 h and 8.7-fold at 12 h. This different expression pattern might be due to the differences in their 3' end region that is responsible for mRNA stability. The 3' end of the H3.2 mRNA contains a stem-loop structure, instead of a poly(A) tail present in the H3.3 mRNA. We also constructed a similar fusion gene using a H3.3 histone gene whose introns had been eliminated to rule out the possibility of involvement of the introns in cell cycle-regulated expression. The expression of this fusion gene was almost identical to the fusion gene made previously. These results indicate that the promoter region of the H3.2 gene is only partially responsible for its expression during the S phase of the cell cycle.
Role of the Promoter Region of a Chicken H3 Histone Gene in Its Cell Cycle Dependent Expression
Son, Seung Yeol 생화학분자생물학회 2000 BMB Reports Vol.32 No.4
We fused the promoter region of an H3.2 chicken histone gene, whose expression is dependent on the cell cycle, to the S' coding region of an H3.3 chicken histone gene, which is expressed constitutively at a low level throughout the cell cycle. This fusion gene showed a cell cycle-regulated pattern of expression, but in a different manner. The mRNA level of the fusion gene increased during the S phase of the cell cycle by about 3.7-fold at 6 h and 2.7-fold at 12 h after the serum stimulation. The mRNA level of the intact H3.2 gene, however, increased by an average of 3.6-fold at 6 h and 8.7-fold at 12 h. This different expression pattern might be due to the differences in their 3' end region that is responsible for mRNA stability. The 3' end of the H3.2 mRNA contains a stem-loop structure, instead of a poly(A) tail present in the H3.3 mRNA. We also constructed a similar fusion gene using a H3.3 histone gene whose introns had been eliminated to rule out the possibility of involvement of the introns in cell cycleregulated expression. The expression of this fusion gene was almost identical to the fusion gene made previously. These results indicate that the promoter region of the H3.2 gene is only partially responsible for its expression during the S phase of the cell cycle.
Son, Seung Yeol,Tae, Gun Sik 한국미생물 · 생명공학회 1994 Journal of microbiology and biotechnology Vol.4 No.4
We subcloned two chicken H3 histone genes and transfected them into Rat 3 cell line. One contains 300 by 5' to its cap site and the other contains 130 by 5' to its cap site when cloned into plasmids. Both of them showed S phase specific expression of their mRNA about 8 fold higher (during S phase) than during G1 phase. This means that only 130 by 5' to its cap site was enough to confer cell cycle regulated expression of the latter gene. The DNA sequences of their 5' flanking region did not reveal any particular homologies or subtype-specific sequences. The DNA sequence data also showed that even though the protein coding regions of the histone genes have been conserved exceptionally well throughout evolution, their 5' untranslated regions have not been conserved as well.
Expression of Chimeric Chicken-Yeast-Chicken H2B Histone Gene
Son, Seung Yeol,Lee, Ho 한국미생물 · 생명공학회 1993 Journal of microbiology and biotechnology Vol.3 No.3
A chicken H2B histone gene was cloned and expressed in Rat 3 cell line. Its messenger RNA level was about 10 times higher during S phase than during G_1 phase. A chimeric chicken-yeast-chicken H2B histone gene was made to change some of wobble sequences of chicken H2B gene. When the chimeric H2B gene was transfected into the Rat 3 cell line, it showed a pattern of expression similar to that of the original chicken H2B gene. At least in this gene, it was concluded that the wobble sequences were not required for the cell-cycle regulated pattern of expression.
Expression of Replication-Independent Chicken H3.3 Histone Gene without Introns
Son, Seung-Yeol,Hong, Bum-Shik Korean Society for Biochemistry and Molecular Biol 1997 Journal of biochemistry and molecular biology Vol.30 No.3
We eliminated introns from replication independent chicken H3.3 histone gene using a H3.3 cDNA clone and a genomic H3.3 clone. After introduction into Rat 3 cells, we observed its pattern of expression by analyzing mRNA from different phases of the cell cycle. Even without introns, the H3.3 gene was expressed constitutively at a low level throughout the cell cycle. This indicates that the introns in the H3.3 gene are not responsible for the cell cycle-independent expression of the gene. This result contradicts previous reports that suggested their importance in cell cycle regulated expression. We believe that other regions of the gene, promoter, coding region, and/or 3'-end of the gene, are involved in its expression pattern.