• Korean Journal of Environmental Biology
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• v.22 no.2
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• pp.329-335
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• 2004

To develop a biomarker for the monitoring of the contamination of estrogenic endocrine disrupters in the aquatic environment, reverse transcription -polymerase chain reaction (RT-PCR) analysis of vitellogenin (Vg) mRNA expression was optimized in Bombina orientalis, a Korean red bellied toad species. Based on partial cDNA sequences of both Vg and beta actin genes of B. orientalis, specific primers for RT-PCR of Vg and beta actin mRNAs were developed. Semiquantitative RT-PCR of the Vg mRNA in liver was optimized using a beta actin mRNA as an internal control in both sexes. In female RT-PCR using $1\;\mu{g}$ of the liver cDNA resulted in a linear increment in the PCR product of Vg from 18 to 34 cycles of amplification. In male, on the contrary, the RT- PCR product was first detected at 30 cycles of amplification and a linear increment was observed from 30 to 40 cycles of amplification, suggesting that male B. orientalis expresses minute amount of Vg mRNA which is a $2^{-12}$ equivalent of female. In conclusion, the optimized protocol for semiquantitative RT-PCR analysis of Vg mRNA level in B. orientalis male liver will be useful for the environmental monitoring the xenoestrogen contamination in the freshwater environment in Korea.

• Environmental Mutagens and Carcinogens
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• v.23 no.1
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• pp.23-29
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• 2003

To determine the frequencies of the genotypes of estrogen metabolising enzyme (CYP17, CYP1A1, CYP1B1, and COMT) and to identify the high-risk genotypes of these metabolic enzymes to breast cancer in Korean, the author has analysed 115 breast cancer patients and corresponding age and sex matched heathy controls using polymerase chain reaction-restiction fragment length polymorphism (PCR-RFLP). A2/A2 genotype in CYP17 polymorphism, m2/m2 genotype in CYP1A1 polymorphism, and Val/Val genotype in CYP1B1 had 0.95, 1.40 and 0.76 relive risks to breast cancer comparing with reference genotypes of each polymorphism, respectively. Among the genotypes of COMT enzyme polymorphism, L/H and L/L genotypes had 0.97 and 1.54 relative risks to breast cancer, respectively. According to the number of high risk genotype, the patients with one or two putative high risk genotypes had 0.95 and 1.94 relative risks to breast cancer, respectively. This study have demonstrated the unique frequency of genotypes of estrogen metabolizing enzyme in Korean healthy women, which will provide the basic data and insights to study the estrogen related conditions in Korean women including breast and endometrial cancers. And it also indicates that the well-known high risk genotypes of estrogen metabolizing enzymes are not significantly associated with the development of breast cancer in Korean women.

• Environmental Mutagens and Carcinogens
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• v.18 no.1
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• pp.15-21
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• 1998

Transgenic animal and cell line models which are recently developed and used in toxicology fields combined with molecular biological technique, are powerful tools to study the mechanism of mutation in vivo and in vitro, respectively. Transgenic models, which have exogenous DNA incorporated into their genome, carry recoverable shuttle vector containing reporter genes to assess endogenous effects or alteration in specific genes related to disease processes. The lac I and lac Z gnee most widely used as a mutational target in transgenic systems. The assay is performed by treatment with putative mutagenic agents, isolation of genomic DNA from cells or tissues, exposure the isolated DNA to in vitro packaging extract, plating and sequencing. The results from these processes provide not only mutant frequency as quantitative evaluation but also mutational spectrum as qualitative evaluation of various agents. Therefore we introduce and review the principle, detailed procedure and application of transgenic mutagenesis assay system in toxicology fields especially in mutagenesis and carcinogenesis.

• Korean Journal of Biological Psychiatry
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• v.10 no.1
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• pp.45-53
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• 2003

Debates relevant to the etiology of weight gain or obesity, i.e., the dichotomous understandings about whether obesity arises from the genetic predisposition or from the environmental influences, has long existed. This is an important issue because it is related to the therapists's prejudice when treating patients with obesity. In this review, the authors first discuss the environmental and the genetic factors that cause the obesity, and in the latter part, the interactions between genetic and environmental factors will be discussed. This issue is considered and described especially in a conceptual aspect for the therapists ultimately to understand how the genetic and the environmental factors interact to arise obesity. Conclusively, obesity is best understood as a complex, multifactorial, and chronic disabled state, which cause an individual with genetic predispostion to obesity under the environmental influences. In future, in favor of the accumulated knowledge about the genetic and environmental impacts and their interactions in detail, we will be able to provide a client-specific management or prevention of obesity.

• Korean Journal of Environmental Biology
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• v.21 no.1
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• pp.52-55
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• 2003

There is considerable evidence that ionizing radiation (IR) mediates checkpoint control, repair and cell death. In this study, we have used a high density microarray hybridization approach to characterize the transcriptional response of human breast carcinoma MCF-7 cell line to ${\gamma}$-radiation, such as 4 Gy 4 hr, 8 Gy 4 hr, and 8 Gy 12 hr. We found that exposure to ${\gamma}$-ray alters by at least a $log_2$ factor of 1.0 the expression of 115 known genes. Of the 66 genes affected by ${\gamma}$-radiation, 49 are down-regulated. In our results, the cellular response to irradiation includes induction of the c-jun and EGR1 early response genes. The present work has examined potential cytoplasmic signaling cascades that transduce IR-induced signals to the nucleus. 40S ribosomal protein s6 kinase modulates the activities of the mitogen activated protein kinase (MAPK) and c-Jun $NH_2$-terminal kinase (JNK1) cascades in human monocytic leukemia (U937/pREP4) cells. 14-3-3 family members are dimeric phosphoserine -binding proteins that participate in signal transduction and checkpoint control pathways.

• Journal of environmental and Sanitary engineering
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• v.22 no.1 s.63
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• pp.75-83
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• 2007

Clove extract by methanol increased expression of the tyrosinase gene on B16 mouse melanoma cells containing tyrosinase promoter. $10{\mu}g/mL$ and $100{\mu}g/mL$ of the extract showed expression rate of the tyrosinase gene about 138% and 245%, respectively, compared with control. At $500{\mu}g/mL$, expression rate of the extract was impossible to measurement by high cytotoxicity. The solvent fraction of methylene chloride also exhibited highly expression rate as methanol extract. However, the solvent fractions of butyl alcohol and water showed repressive effect on expression of tyrosinase gene at $500{\mu}g/mL$. In MTT assay, cell survival rate of the extract exhibited similar to expression rate of tyrosinase gene. That is, $10{\mu}g/mL$ and $100{\mu}g/mL$ of the extract showed the cell survival rate about 128% and 187%, respectively.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.697-704
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• 2007

This study proposes an integrated technique of Genetic Algorishim (GA) and Geographic Information System (GIS) for designing the water quality monitoring networks. To develop solution scheme of the integrated system, fitness functions are defined by the linear combination of five criteria which stand for the operation objectives of water quality monitoring stations. The criteria include representativeness of a river system, compliance with water quality standards, supervision of water use, surveillance of pollution sources and examination of water quality changes. The fitness level is obtained through calculations of the fitness functions and input data from GIS. To find the most appropriate parameters for the problems, the sensitivity analysis is performed for four parameters such as number of generations, population sizes, probability of crossover, and probability of mutation. Using the parameters resulted from the sensitivity analysis, the developed system proposed 110 water quality monitoring stations in the Nakdong River. This study demonstrates that the integrated technique of GA and GIS can be utilized as a decision supporting tool in optimized design for a water quality monitoring network.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.359-365
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• 2004

The change of chlorophyll fluorescence parameters, O-J-I-P transients and psbA gene expression were investigated in the leaves of Crinum asiaticum var. japonicum on the natural condition in winter, in order to elucidate physiological responses of photosystem II (PS II) activity to winter stresses. The photochemical efficiencies of PS II, Fv/Fm, were significantly low in winter, contrary to its high value in summer. The values of I -qN and I-qP were lower in midday than at dawn or night both in summer and winter, although their decrease in midday was less in winter than in summer. In the O-J-I-P transients, the fluorescence intensity of J, I, P-step decreased remarkably depending on temperature drop in winter. And the D I reaction center protein of PS II decreased in late winter more than in early winter, concomitantly with relatively high content of description products of psbA gene in midday. These results indicate that low temperature in winter causes irreversible damage to PS II and subsequently leads to cell death.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.5
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• pp.395-400
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• 2000

In this paper, we propose a new neuro-fuzzy controller based on reinforcement learning. The proposed system is composed of neuro-fuzzy controller which decides the behaviors of an agent, and dynamic recurrent neural networks(DRNNs) which criticise the result of the behaviors. Neuro-fuzzy controller is learned by reinforcement learning. Also, DRNNs are evolved by genetic algorithms and make internal reinforcement signal based on external reinforcement signal from environments and internal states. This output(internal reinforcement signal) is used as a teaching signal of neuro-fuzzy controller and keeps the controller on learning. The proposed system will be applied to controller optimization and adaptation with unknown environment. In order to verifY the effectiveness of the proposed system, it is applied to collision avoidance of an autonomous mobile robot on computer simulation.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1139-1147
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• 2012

To find out the growth conditions for the maximum activity of nitrogenase which catalyzes nitrogen fixation in Rhodobacter sphaeroides, the promoter activities of nifA and nifH were analyzed and the results indicated that expression of both nifA and nifH was increased in response to deprivation of both O2 concentration and nitrogen source. The nifA mutant was constructed by deleting the gene to investigate the effect of NifA, the transcriptional regulator, on the nifH and nifA expression in R. sphaeroides. Analysis of expression of nif genes using the nifA::lacZ and nifH::lacZ fusions in the nifA mutant revealed that NifA acts as a positive activator for nifH and an autoregulator in its own expression. The promoter activities of nifA and nifH in the prrA mutant grown under anaerobic and ${NH_4}^+$-free conditions were derepressed, comparing with those of the wild-type grown under the same conditions, indicating that the prrA product acts as a positive regulator in expression of nifA and nifH.