• 한국발생생물학회지:발생과생식
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• 제2권2호
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• pp.197-203
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• 1998

포유류 배아발생 중 DNA 메틸화는 세포분화와 유전자발현에서 중요한 역할을 하는 것으로 알려져 있다. 그러나, 생쥐 착상전 초기배아 발생 중 메틸화효소에 의해 유지되는 DNA 메틸화의 중요성과 자세한 기작은 잘 이해되고 있지 않다. 이 연구에서 DNA 메틸화의 역할에 관하여 알아보기 위하여, 성숙난자와 착상전 초기배아에서 DNA 메틸전이효소의 발현양상을 조사하였다. 이를 위해, DNA 메틸전이효소를 암호화하고 있는 cDNA에서 primer를 고안하였다. Primer의 정확도와 PCR조건의 적합화를 통하여, DNA MTase 전사물이 성숙난자와 착상전 초기배아에서 검출되었다. DNA MTase의 mRNA량은 성숙난자에서 가장 높으며, 전핵시기까지 비슷한 정도로 유지되었다. 이후 8-세포기까지 지속적으로 감소하다 상실기 배아에서 다시 검출되어 포배기까지 증가하는 양상을 보였다. 그리고, RNA polymerase II 억제제를 전핵시기 배아에 처리하여, 난자와 전핵시기 배아에 다량 존재하는 전사물이 모계유래인 것을 확인하였다. 결국, 난자와 전핵시기 배아에 상대적으로 다량 존재하는 DNA 메틸전이효소의 전사물은 아마도 착상전 초기배아에서 DHA 메틸화의 유지에 필요하며, 착상전 초기배아 발생에 있어서 유전자발현과 세포분화에 영향을 줄 것임을 시사하고 있다.

• 대한의생명과학회지
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• 제11권2호
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• pp.165-173
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• 2005

A potent demethylating agent, 5-Azacytidine (5-AzaC) has been widely used as in many studies on DNA methylation, regulation of gene expression, and cancer biology. The mechanisms of the demethylating activity were known to be formation of complex between DNA and DNA methyltransferase (MTase), which depletes cellular MTase activity. However, 5-AzaC can also induce hypermethylation of a transgene in a transgenic cell line, G12 cells and it was explained as a result of defense mechanisms to inactivate foreign gene(s) somehow. This finding evoked the question that whether the phenomenon of hypermethylation induced by 5-AzaC is limited to the transgene or it can be occurred in endogenous gene(s). In order to answer the question, mutagenicity test of 5-AzaC and molecular characterization of mutants obtained from the test were performed using an endogenous gene, thymidine kinase (tk) in Chinese hamster V79 cells. When V79 and V79-J3 subclone cells were treated with 1, 2.5 ,5, $10{\mu}M$ of 5-AzaC for 48 hours, their maximum mutant frequencies were revealed as $6\times10^{-3}\;at\;5{\mu}M$(350-fold induction over background) and $8\times10^{-3}\;at\;2.5{\mu}M$ (l,800-fold induction over background) respectively. Since the induction rates were too high to be induced by true mutations, many trifluorothymidine (TFT)-resistant $(TFT^R)$ cells were subjected to Northern blot analysis to check the presence of tk transcripts. Surprisingly, all clones tested possessed the transcripts in a similar level, that implicates the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the gene in spite of unusually high mutation frequency. In addition, it has shown that the TK activity in the pool of 5-AzaC-induced $TFT^R$ cells has about a half of that in spontaneously-induced $TFT^R$ cells or in non-selected parental V79-J3 cells. This result suggests that the mechanism(s) underlying the TFT-resistance between spontaneously occurred and 5-AzaC-induced cells may be different. These findings have shown that the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the tk gene, and 5-AzaC may be induced by one or combined pathways among many drug resistance mechanisms. The exact mechanisms for the 5-AzaC-induced $TFT^R$ phenotype remain to elucidate.

• Asian-Australasian Journal of Animal Sciences
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• 제25권6호
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• pp.895-902
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• 2012

The Korean native chickens (Woorimotdak$^{TM}$, KNC) and commercial broilers (Ross, CB) show obvious differences in meat flavor after cooking. To understand the contribution of protein and peptide for meat flavor, 2-dimensional (2-D) gel electrophoresis and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry was performed. A total of 16 protein spots were differentially expressed in the breast and thigh meat between the two breeds. A total of seven protein spots were represented by different levels between KNC and CB for breast meat. Among them three protein spots (TU39149, TU40162 and TU39598) showed increases in their expressions in KNC while other four protein spots (BU40125, BU40119, BU40029 and BU39904) showed increases in CB. All nine protein spots that were represented by different levels between KNC and CB for thigh meat showed increases in their expression in KNC. Phosphoglucomutase 1 (PGM 1), myosin heavy chain (MyHC), heat shock protein B1 (HSP27), cytochrome c reductase (Enzyme Q), Glyoxylase 1, DNA methyltransferase 3B (DNA MTase 3) were identified as the main protein spots by MALDI-TOF mass spectrometry. These results can provide valuable basic information for understanding the molecular mechanism responsible for breed specific differences in meat quality, especially the meat flavour.