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박기연,곽인실 환경독성보건학회 2014 환경독성보건학회지 Vol.29 No.-
Objectives Heat shock protein 90 (HSP90) is a highly conserved molecular chaperoneimportant in the maturation of a broad spectrum of protein. In this study, an HSP90gene was isolated from Asian paddle crab, Charybdis japonica, as a bio-indicator tomonitor the marine ecosystem. Methods This work reports the responses of C. japonica HSP90 mRNA expression tocellular stress by endocrine disrupting chemicals (EDCs), such as bisphenol A (BPA) and4-nonylphenol (NP) using real-time. reverse transcription polymerase chain reaction. Results The deduced amino acid sequence of HSP90 from C. japonica shared a highdegree of homology with their homologues in other species. In a phylogenetic analysis,C. japonica HSP90 is evolutionally related with an ortholog of the other crustacean species. The expression of HSP90 gene was almost distributed in all the examined tissuesof the C. japonica crab but expression levels varied among the different body parts of thecrabs. We examined HSP90 mRNA expression pattern in C. japonica crabs exposed toEDCs for various exposure times. The expression of HSP90 transcripts was significantlyincreased in C. japonica crabs exposed to BPA and NP at different concentrations for 12,24, 48 and 96 hours. The mRNA expression of HSP90 gene was significantly induced ina concentration- and time-dependent manner after BPA or NP exposures for 96 hours. Conclusions Taken together, expression analysis of Asian paddle crab HSP90 gene provideduseful molecular information about crab responses in stress conditions and potentialways to monitor the EDCs stressors in marine environments.
STD11 금형강 재열처리에 따른 미세조직 및 기계적 특성
박기연,권의표,허기호,Park, Gi Yeon,Kwon, Eui Pyo,Heo, Gi Ho 한국재료학회 2022 한국재료학회지 Vol.32 No.3
Reheat treatment process of mold is necessary when partial machining of the mold is required, such as shape correction for an existing mold. If defects such as cracks or significant deterioration of mechanical properties of the mold occur during reheat treatment, it is impossible to reuse the mold. In this study, reheat treatment was performed up to two times for STD11 tool steel, and microstructure and mechanical properties according to the reheat treatment were evaluated. Carbide fraction and grain size of prior austenite were almost unchanged after the reheat treatment. Hardness and impact toughness increased significantly after QT treatment, and these properties were maintained without significant change even after the reheat treatment. It is concluded that up to two iterations of reheat treatment does not cause deterioration of properties of STD11 tool steel. Based on these results, a mold for a face-lifted front bumper was manufactured through machining and reheat-treating of an existing mold.
박기연,김원석,곽인실 한국해양과학기술원 2019 Ocean science journal Vol.54 No.4
The ecdysone receptor (EcR) induces hormonal pathways by binding ecdysteroids to other nuclear receptors for development, reproduction, and molting processes. To further understand the role of EcR in polluted environments, we characterized EcR and assessed the transcriptional responses of the EcR gene to osmotic stress, and to endocrine disrupting chemicals (EDCs) such as bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) in the intertidal mud crab Macrophthalmus japonicus. Phylogenetic analysis showed that the ligand binding domain of M. japonicus EcR formed two different clusters among crab species. Osmotic stress prompted different expression patterns of EcR mRNA in M. japonicus crabs under low and high salinities. BPA exposure induced significant up-regulation of EcR as early as day 1 in M. japonicus gills and hepatopancreas. However, the expression levels of EcR returned to similar, or lower, levels as controls, by days 4 and 7. In contrast, EcR mRNA expression was significantly induced in M. japonicus gills and hepatopancreas exposed to most of the DEHP concentrations over all exposure times. Hepatopancreatic tissue is more sensitive than gill tissue in terms of EcR gene responses to EDCs. Taken together, these results suggest that the role of EcR in endocrine protection may involve different processes according to the type of EDCs and up-regulatory responses of the EcR transcript could be used as an indicator for detecting changes in hormonal systems caused by environmental stressors.