• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1026-1035
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• 2015

Condensin is not only responsible for chromosome condensation, but is also involved in double-strand break (DSB) processing in the cell cycle. During meiosis, the condensin complex serves as a component of the meiotic chromosome axis, and mediates both proper assembly of the synaptonemal complex and DSB repair, in order to ensure proper homologous chromosome segregation. Here, we used the budding yeast Saccharomyces cerevisiae to show that condensin participates in a variety of chromosome organization processes and exhibits crucial molecular functions that contribute to meiotic recombination during meiotic prophase I. We demonstrate that Ycs4 is required for efficient DSB formation and establishing homolog bias at the early stage of meiotic prophase I, which allows efficient formation of interhomolog recombination products. In the Ycs4 meiosis-specific allele (ycs4S), interhomolog products were formed at substantial levels, but with the same reduction in crossovers and noncrossovers. We further show that, in prophase chromosomal events, ycs4S relieved the defects in the progression of recombination interactions induced as a result of the absence of Rec8. These results suggest that condensin is a crucial coordinator of the recombination process and chromosome organization during meiosis.

• Journal of The Korean Association For Science Education
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• v.13 no.2
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• pp.219-229
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• 1993

The purpose of this study is to investigate college science students' and science teachers' understanding of chromosomal behavior in the context of cell division. The research problems were as follows: 1. What is the level of college science students' understandings of chromosomal behaviors? 2. What is the level of science teachers' understandings of chromosomal behaviors? 3. What is the level of understanding by grade and major area? The sample consisted of 28 sophomore, 17 junior and 23 senior biology students; and 23 middle school science teachers and 14 high school biology teachers. The instrument of the study was a short answer required paper and pencil test. The results of the study were as follows: 1) About 15 percent of the sample could not count the number of chromosome in a cell in appropriate. 2) Seventy percent of the students, and 80 percent of the teachers identified homologous chromosomes as ones with the similar shape and size, and 30 percent of the whole sample could not pair two homologous chromosomes. 3) About 70 percent of the students and 30 percent of the teachers could not mark corresponding allele on chromosome. 4) Biology major students showed higher understanding of overall chromosomal behaviors than non Biology students. Based upon the results, some implications were made. The major one was a development of a teaching model in which students can improve the ability to connect chromosome theory to mendelian genetics.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.4
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• pp.446-451
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• 1997

A Giemsa C-banding method was used for the identification of somatic chromosomes and heterochromatic knob positions in Korean indigenous maize(Zea mays L.). Total of 10 inbred stocks were examined and their knob numbers ranged from 6 to 12. In comparison of homologous chromosomes of two stocks of Waesungri and PI 213749, arm ratios and relative length of chromosomes were different between genotypes. In comparison of arm ratios, all the homologous chromosomes except chromosome 2 were different each other. In comparison of relative length of chromosomes, that of chromosome 1 in Waesungri and PI213749 was 223.22 and 192.03 respectively. The relative length of homologous chromosomes in Waesungri were generally lager than those of PI213749. A C-banded diagram showing knob positions, arm ratios and relative length of chromosome could be used as a good tool to compare the characteristics of chromosomes of Korean indigenous maize stocks.

• Korean Journal of Plant Tissue Culture
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• v.25 no.6
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• pp.453-475
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• 1998

During the 100 years since the initial discovery of meiotic phenomenon many brilliant aspects have been elucidated, but further researches based on light microscopy alone as an experimental tool have been found to have some limits and shortcomings. By the use of electron microscopy and armed with the advanced knowledges on modern genetics and biochemistry it has been possible to applu molecular technology in gaining information on the detailed aspects of meiosis. As synapsis takes place, a three-layered proteinous structure called the synatonemal complex starts to form in the space between the homologous chromosomes. To be more precise, it begins to form along the paired chromosomes early in the prophase I of meiotic division. The mechanism that leads to precise point-by-point pairing between homologous chromocomes division. The mechamism that leads to precise point-by-point pairing between homologous chromosomes remains to be ascertained. Several items of information, however, suggest that chromsome alignment leading to synapsis may be mediated somehow by the nuclear membrane. Pachytene bivalents in eukaryotes are firmly attached to the inner niclear membrane at both termini. This attached begins with unpaired leptotene chromosomes that already have developed a lateral element. Once attached, the loptotene chromosomes begin to synapse. A number of different models have been proposed to account for genetic recombination via exchange between DNA strands following their breakage and subsequent reunion in new arrangement. One of the models accounting for molecular recombination leading to chromatid exchange and chiasma formation was first proposed in 1964 by Holliday, and 30 years later still a modified version of his model is favored. Nicks are made by endomuclease at corresponding sites on one strant of each DNA duplex in nonsister chromatid of a bivalent during prophase 1 of meiosis. The nicked strands loop-out and two strands reassociate into an exchanged arrangement, which is sealed by ligase. The remaining intact strand of each duplex is nicked at a site opposite the cross-over, and the exposed ends are digested by exonuclease action. Considerable progress has been made in recent years in the effort to define the molecular and organization features of the centromere region in the yeast chromosome. Centromere core region of the DNA duplex is flanked by 15 densely packed nucleosomes on ons side and by 3 packed nucleosomes on the other side, that is, 2000 bp on one side and 400 400 bp in the other side. All the telomeres of a given species share a common DNA sequence. Two ends of each chromosome are virtually identical. At the end of each chromosome there exist two kinds of DNA sequence" simple telpmeric sequences and telpmere-associated sequencies. Various studies of telomere replication, function, and behabior are now in progress, all greatly aided by molecular methods. During nuclear division in mitosis as well as in meiosis, the nucleili disappear by the time of metaphase and reappear during nuclear reorganizations in telophase. When telophase begins, small nucleoli form at the NOR of each nucleolar-organizing chromosome, enlarge, and fuse to form one or more large nucleoli. Nucleolus is a special structure attached top a specific nucleolar-organizing region located at a specific site of a particular chromosome. The nucleolus is a vertical factory for the synthesis of rRNAs and the assenbly of ribosome subunit precursors.sors.

• Korean Journal of Medicinal Crop Science
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• v.11 no.4
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• pp.311-315
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• 2003

This study was carried out to compare chromosomal characteristics between Atractylodes japonica and A macrocephala. Cytogenetic analysis was conducted based on karyotype analysis and physical mapping using fluorescence in situ hybridization. As a result of karyotype analysis by feulgen staining, somatic chromosome numbers of A. japonica and A. macrocephala were 2n=24. The length. of the mitotic metaphase chromosomes of A. japonica ranged from $0.70\;to\;1.60{\mu}m$ with a total length. of $12.11{\mu}m$ and the homologous chromosome complement comprised six metacentrics, five submetacentrics and one subtelocentrics. On the other hand, the length of the mitotic metaphase chromosomes of A. macrocephala ranged from $0.90\;to\;2.35{\mu}m$ with a total length of $16.58{\mu}m$ and the homologous chromosome complement comprised seven metacentrics and five submetacentrics. The total length of A. japonica chromosomes was shorter than that of A. macrocephala, but A. japonica had one subtelocentrics (chromosomes 4) different from A. macrocepha1a. chromosomes. The F1SH technique using 17S and 5S rDNA was applied to metaphase chromosomes. The signals for 17S rDNA were detected on the telomeric regions of chromosomes 4 and 5 in both A japonica and A. macrocephala. The 5S rDNA signal was found in the short arm of chromosome 1.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.376-378
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• 2004

Genetic algorithm was motivated by biological evaluation and has been applied to many industrial applications as a powerful tool for mathematical optimizations. In this paper, a new genetic optimization algorithm is proposed. The proposed method is based on Mendel's law, especially dominance and recessive property. Homologous chromosomes are introduced to implement dominance and recessive property compared with the standard genetic algorithm. Because of this property of suggested genetic algorithm, homologous chromosomes looks like the chromosomes for the standard genetic algorithm, so we can use most of existing genetic operations with little effort. This suggested method searches the larger solution area with the less probability of the premature convergence than the standard genetic algorithm.

• Journal of Life Science
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• v.10 no.2
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• pp.50-54
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• 2000

The RAD4 gene of Saccharomyces cerevisiae is essential for the incision step of UV-induced excision repair. A yeast RAD4 gene has been previously isolated by functional complementation. In order to identify the RAD4 homologous gene from fungus Coprinus cinereus, we have constructed cosmid libraries from electrophoretically separated chromosomes of the C. cinereus. The 13 C. cinereus chromosomes were resolved by pulse-field gel electrophoresis, hybridized with S. cerevisiae RAD4 DNA, and then isolated homologous C. cinereus chromosome. Here, we report the cloning and characterization of fungus C. cinereus homolog of yeast RAD4 gene. Southern blot analysis confirmed that C. cinereus contains the sequence homologous DNA to RAD4 gene and this gene exists as a single copy in C. cinereus genome. When total RNA isolated from C. cinereus cells was hybridized with the 3.4 kb BglII DNA fragment of the S. cerevisiae RAD4 gene, a 2.5 kb of transcript was detected. The isolated gene encodes a protein of 810 amino acids.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.598-605
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• 2015

The cohesin complex holds sister chromatids together and prevents premature chromosome segregation until the onset of anaphase. Mcd1 (also known as Scc1), the α-kleisin subunit of cohesin, is a key regulatory subunit of the mitotic cohesin complex and is required for maintaining sister chromatid cohesion, chromosome organization, and DNA repair. We investigated the function of Mcd1 in meiosis by ectopically expressing Mcd1 during early meiotic prophase I in Saccharomyces cerevisiae. Mcd1 partially regulated the progression of meiotic recombination, sister chromatid separation, and nuclear division. DNA physical analysis during meiotic recombination showed that Mcd1 induced double-strand breaks (DSBs) but negatively regulated homologous recombination during DSB repair; Mcd1 expression delayed post-DSB stages, leading to inefficiencies in the DSB-to-joint molecule (JM) transition and subsequent crossover formation. These findings indicate that meiotic cells undergo Mcd1-mediated DSB formation during prophase I, and that residual Mcd1 could regulate the progression of JM formation during meiotic recombination.

• Environmental Mutagens and Carcinogens
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• v.17 no.1
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• pp.1-6
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• 1997

The RAD4 gene of Saccharomyces cerevisiae is essential for the incision step of UV-induced excision repair. A yeast RAD4 gene has been previously isolated by functional complementation. In order to identify the RAD4 homologous gene from fungus Coprinus cinereus, we have constructed cosmid libraries from electrophoretically separated chromosomes of the C. cinereus. The 13 C. cinereus chromosomes were resolved by pulse-field gel electrophoresis, hybridized with S. cerevisiae RAD4 DNA, and then isolated homologous C. cinereus chromosome. The insert DNA of the RAD4 homolog was contained 3.2 kb. Here, we report the partial cloning and characterization of fungus C. cinereus homolog of yeast RAD4 gene. Southern blot analysis confirmed that C. cinereus contains the sequence homologous DNA to RAD4 gene and this gene exists as a single copy in C. cinereus genome. When total RNA isolated from C. cinereus cells was hybridized with the 1.2 kb PvuII DNA fragment of the S. cerevisiae RAD4 gene, a 2.5 kb of transcript was detected. The level of the transcript did not increase upon UV-irradiation, suggesting that the RAD4 homologous gene in C. cinereus is not UV-inducible.

• KSBB Journal
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• v.24 no.3
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• pp.279-286
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• 2009

Streptomyces is well known for their ability to synthesize enormous varieties of antibiotics as secondary metabolites. Among them, S. avermitilis produces avermectins, a group of antiparasitic agents used in human and veterinary medicine. However, S. avermitilis also produces oligomycin, which is a potential toxic inhibitor of oxidative phosphorylation in mammalian cells. Therefore, we decided to disrupt oligomycin synthetase gene to prevent co-production of oligomycin in S. avermitilis. To create plasmid for disruption, the smallest gene of oligomycin synthetase gene cluster was obtained by PCR from S. avermitilis chromosome. Then, apramycin resistance gene was inserted in oligomycin synthetase gene for selection. After transformation of this plasmid, oligomycin synthetase gene (olmA5) in the chromosome was displaced with disruption cassette on the plasmid via homologous recombination. As a result of this gene replacement, we obtained mutants (olmA5::apra) that no longer makes the toxic oligomycin. And the mutants confirmed by PCR and HPLC analysis. However, showed no increasement of avermectin production in the mutant was observed.