• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.142-148
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• 2001

We studied adaptive response in CHL cells by benzidine dihydrochloride, a derivative of benzidine, which was a major mutagenic agent in dye industry. Chromosome aberration analysis was used for the identification of adaptive response to this mutagen. Adaptive and reactive doses were confirmed by cell proliferation rate curve. Cell proliferation rate curve was obtained from the mitotic indices of cells treated with various concentrations of benzidine dihydrochloride for 24 hours. Marked adaptive responses to benzidine dihydrochloride in the induction of chromosome aberration were observed in CHL cells by pre-treatment with low concentrations of benzidine dihydrochloride (0.0047 mg/$m\ell$ or 0.0094 mg/$m\ell$) for 24 hours following post-treatment with high concentrations (0.0187, 0.0375, 0.075, 0.15 mg/$m\ell$) for 24 hours. These adaptive responses were found mostly in the type of chromatid breaks and chromatid exchanges. There is no difference in these results between two adaptive doses, 0.0047 mg/$m\ell$ and 0.0094 mg/$m\ell$. The amount of adaptive response, however, was dependent on post-treatment doses.

• Toxicological Research
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• v.11 no.2
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• pp.261-266
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• 1995

Age-related change in the frequency of spontaneous sister chromatid exchange (SCE) and chromosornal aberrations were investigated in bone marrow cells of accelerated senescence-resistant mice (SAM R1) and senescence accelerated ones (SAM P1). And the effect of chronic treatment of ginseng extract (Panax ginseng C.A. Meyer) on these chromosomal abnormalities was tested in SAM P1. SCE frequency in the cells was progressively increased with age in both mice, but it was consistently higher in SAM P1 than in SAM R1 at all corresponding age. Chromosomal aberrations were, however, not significantly changed with age except that it was slightly increased in only aged SAM P1. Interestingly, the rate of these genetic instabilities in SAM P1 was remarkably retarded by long-term administration of ginseng water extract (0.05% in drinking water). These results suggest that frequency of spontaneous SCE in bone marrow cells increase in parallel with senescence of the mice, and SAM P1 is in the condition of being more exposed than SAM R1 to DNA damaging factors. These also indicate that long-term treatment of ginseng may reduce the genetic damage.

• Environmental Mutagens and Carcinogens
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• v.25 no.3
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• pp.110-117
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• 2005

DEHP is one of well known endocrine disrupter and it is used as additives for the production of PVC. There has been contradictional result on the genotoxicity of DEHP. In order to examine genotoxicity of a endocrine disruptors, DEHP (Di-2-EthylHexyl Phthalate) and it's metabolites, EHA (2-EthylHexanoic Acid) and DEP (Di-2-Ethyl Phthalate), chromosome aberration (CA), sister chromatid exchange (SCE), micronuclei (MN) and single cell gel electrophoresis were analysised. No increase of the frequency of CA was observed by DEHP and its two metabolites. DEHPincreased the frequency of SCE and MN whereas EHA only increased the frequency of SCE. DEP increased the frequency of SCE but the increase was not statistically significant. DEHP and DEP, also induced DNA damage. It is suggested that combination of different methods were recomended to find the genotoxicity of DEHP and its metabolites.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.533-544
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• 1994

정신분열 살인환자로 격리 치료를 받고 있는 집단을 대상으로 이들을 치료하고자 복용시키는 Haloperidol, Perphenazine, Lithium carbonate 등과 같은 항정신질환 치료제가 자매염색분체 교환(Sister Chromatid Exchange SCE)에 미치는 영향을 조사하였다. 항정신질환 치료제를 계속적으로 복용하고 있는 환자 100명(남자: 76명, 여자: 24명)과 치료제를 전혀 복용하지 않은 남자 환자 10명을 대조군으로 하여 SCE의 빈도를 분석한 결과 항정신질환 치료제를 복용한 환자군에서의 SCE 평균빈도는 세포당 12.24$\pm$0.20으로 항정신질환 치료제를 복용하지 않은 대조군에서의 평균빈도인 세포당 8.77$\pm$0.20보다 높아 유의한 차이를 볼 수 있었다 그러나 항정신질환 치료제를 복용하지 않은 대조군에서의 평균빈도는 이미 보고된 바 있는 정상인 한국인 집단에서의 평균빈도인 세포당 8.78$\pm$0.24(Park et al. , 1992)와 별 차이가 없었다 한편 항정신질환 치료제를 장기간 복용하는데 따른 SCI 빈도의 차이가 있는지의 여부를 보기 위하여 1년 미만에서 6년 정도까지의 치료제 복용기간에 따른 SCE의 평균빈도를 비교 분석한 바 복용기간에 따른 SCE 평균빈도의 유의한 차이는 볼 수 없었다. 정신분열환자들이 복용하고 있는 항정신질환 치료제가 SCE에 영향을 줄 수 있다는 결과를 얼었다.

• The Korean Journal of Zoology
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• v.19 no.2
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• pp.71-78
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• 1976

Chromosome aberration induced by methyl methanesulfonate (MMS) and the effects of thymidine analogs (BUdR or IUdR) on MMS-induced chromosome aberration were studied in human lymphocyte cultures. Single treatment with MMS to lymphocytes induces both chromatid and chromosome type aberrations with high frequency of chromatid type. The combined treatment of BUdR or IUdR with MMS was found to be more effective in increasing the rate of chromosome type aberrations.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.26-32
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• 1997

To evaluate the cytogenetic toxicity, of cadmium and the reducing effect of selenium or zinc on cadmium toxicity, the induction of SCEs in cultured human lymphocytes by the concentraion of 0.5 $\mu$M to 16.0 $\mu$M of cadmium chloride and those of cadmium chloride combined with sodium selenite or zinc chloride 1.2 $\mu$M, respectively was investigated. The induction of SCEs by cadmium chloride in the range of 0.5 $\mu$M to 16.0 $\mu$M increased in a dose-dependent manner. A notable increase in SCEs by sodium selenite as well as zinc chloride was also observed. However, the frequency of SCEs by cadmium chloride was inhibited by the simultaneous addition of sodium selenite and zinc chloride 1.2 $\mu$M, respectively. The mitotic index significantly decreased in higher concentration of cadmium chloride but not was significantly different in any concentration of cadmium chloride with the simultaneous addition of sodium selenite or zinc chloride. The results showed that the decreased additive SCE effect was observed when induced by the combined treatment which could suggest that sodium selenite and zinc chloride have a protective effect on cadmium chloride.

• Environmental Mutagens and Carcinogens
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• v.25 no.4
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• pp.150-156
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• 2005

Analysis of chromosome aberration (CA) and cytokinesis-block micronucleus (CBMN) assay in peripheral lymphocytes of nurses exposed to low levels of anticancer drug and Ethylene Oxide(EO) gas in a hospital were performed. The frequency of CA was increased in the exposed compared to the controls whereas no increase of the frequency of MN was found. The frequencies of chromatid type CA were 1.2, 3.91 and 9.67 per 500 cells in the controls, workers exposed to anticancer drug and workers exposed to EO, respectively. Lower frequency of CA in nurses handling anticancer drugs with safety covers compared to those without safety covers was observed, but it was not statistically significant. The frequency of CA in nurses handling anticancer drugs increased by the frequency of mixing anticancer drugs. Poisson regression analysis showed a significant association of the frequency of chromatid type CA with age, duration of wort exposure to anticancer drug and EO gas exposure, but no association of the frequency of chromosome type CA with any variables. The results suggested that there were associations between CA and the occupational exposure to low levels of anticancer drug and EO gas.

• The Korean Journal of Zoology
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• v.13 no.1
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• pp.29-33
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• 1970

The conclusions established in the present study on the chromosomes in vitro of the uterine carcinomas of Korean women are as follows: 1. The pattern of the distribution of chromosome number in uterine carcinoma cells was quite different from that of normal cells, and modal number of the chromosome was 45 and 46. 2. The frequency of diplochromosomes was 0.053 per cell (5.3%) and that of chromosome aberration was 0.16 per cell (16%), which are significantly higher than each of normal cells. In chromosome aberration types, chromatid and isochromatid deletions (chromatid type) and dicentric (chromosome type) were observed. 3. Idiogram analysis showed a tendency that the number of chromosomes belonging to group F increased while that of chromosomes in groups B and E decreased in total. The number of chromosomes in groups C and G in the hypodiploidy cells decreased, but it increased in the hyperdiploidy cells.

• 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.

• Journal of Preventive Medicine and Public Health
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• v.19 no.2 s.20
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• pp.244-251
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• 1986

Sister chromatid exchanges(SCEs) and cell cycle kinetics were proposed as a sensitive and quantitative assay for mutagenicity and cytotoxicity in short-term cultures of phytohema-gglutinin(PHA)-stimu1ated human 1ymphocytes. Therefore, this study was performed to investigate the relation between the cytotoxic effects and sister chromatid exchanges. The resultes are summarized as follows: 1) The frequency of SCEs per cell are $13.1{\pm}2.8$ in the lower concentration of $6.25{\times}10^{-9}M\;and\;75.8{\pm}8.2$ in the highest concentration of $1.00{\pm}10^{-7}M$. Mitotic index is decreased in the higher concentration of mitomycin C. The result indicates that mitomycin C led to a dose dependent increase in SCE frequency, but decease in mitotic index. 2) Chromosomal analysis was performed on metaphase cells that have divided one, two, and three or more times for cell cycle kinetics by fluorescence-plus-Giemsa(FPG) technique. According to the increased concentration of mitomycin C, the proportion of metaphase cells in the first are profoundly increased but the cells of third division are greatly decreased. 3) The frequency of SCEs per chromosome by chromosomal group are decreased gradually from A group to G group. But relationships between specific chromosomal group and SCE frequency are not found.