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Epigenetics by DNA Methylation for Normal and Cloned Animal Development
Shiota Kunio 한국발생생물학회 2003 한국발생생물학회 학술발표대회 Vol.2003 No.1
"Epigenetics" means the study of heritable changes in gene-activity without changes in DNA sequences. Methylation of the cytosine residue in a CpG dinucleotide sequence is a characteristic of the vertebrate genome. In vertebrates, methylation of DNA mainly occurs at the 5′-position of cytosine in a CpG dinucleotide forming 5-methylcytosine. Methylation of DNA plays a profound role in transcriptional repression of gene expression through several mechanisms. Generally, DNA of inactive genes is more heavily methylated than that of active ones; conversely demethylation of DNA reactivates gene expression in vivo and in vitro.
Ko, Yeoung‐,Gyu,Yun, Jisoo,Park, Hyoung Joon,Tanaka, Satoshi,Shiota, Kunio,Cho, Jae‐,Hyeon Wiley Subscription Services, Inc., A Wiley Company 2013 Molecular reproduction and development Vol.80 No.3
<P><B>Abstract</B></P><P>DNA methyltransferase1o (<I>Dnmt1o</I>), which is specific to oocyte and preimplantation embryo, plays a role in maintaining DNA methylation in mammalian cells. Here, we investigated the methylation status of CpGs sites in the <I>Dnmt1o</I> 5′‐flanking region in germ cells at different stages of oogenesis or spermatogenesis. The methylation levels of the CpG sites at the 5′‐flanking regions were hypermethylated in growing oocytes of all follicular stages, while the oocytes in meiotic metaphase II (MII) were demethylated. The methylation pattern within the CpGs sites in the 5′‐flanking region, however, was dramatically changed during spermatogenesis. We observed that there was significant non‐CpG methylation both in MII oocytes and spermatocytes. Although a low methylation level in non‐CpG sites was observed in primary and secondary oocytes, the CpA site of position 25 and CpT site of position 29 within the no‐CpG region in the 5′‐flanking region of <I>Dnmt1o</I> was highly methylated in MII oocytes. During spermatogenesis, the low degree of methylation at CpG sites in spermatocytes increased to a higher degree in sperm, while the high ratio of methylation in non‐CpG sites in spermatocytes decreased. Together, germ cells showed inverted methylation patterns between CpG and non‐CpG sites in the <I>Dnmt1o</I> 5′‐upstream region, and the methylation pattern during oogenesis did not drastically change, remaining generally hypomethylated at the MII stage. Mol. Reprod. Dev. 80: 212–222, 2013. © 2013 Wiley Periodicals, Inc.</P>
Seong, H.H.,Min, K.S.,Kang, M.H.,Yoon, J.T.,Jin, H.J.,Chung, H.J.,Chang, W.K.,Yun, S.G.,Shiota, Kunio Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.3
The enzyme $20{\alpha}$-hydroxysteroid dehydrogenase ($20{\alpha}$-HSD) catabolizes progesterone to $20{\alpha}$-dihydroprogesterone ($20{\alpha}$-OHP), and is appeared in rat corpora luteal and placenta. A polled samples of 10-15 placental and ovarian tissues collected from each individual rat were subjected to measurement of $20{\alpha}$-HSD activity. A $20{\alpha}$-HSD activity in the cytosol fraction was based on the generation of NADPH. In this study, it is designed to study cytosolic $20{\alpha}$-HSD activity in rat ovarian and placenta during pregnancy, and its relationship to embryonic mortality. It was found that from days 5 to 18 of pregnancy the $20{\alpha}$-HSD activities steady by decreased but at parturition time rapidly increased in ovary. On the other hand, placental cytosolic $20{\alpha}$-HSD activities were high detected from days 8 to 10 of pregnancy, not detectable from days 11 to 20 of pregnancy, but again very high at the time of parturition. Analysis of DEAE column chromatography revealed that two different types of $20{\alpha}$-HSD (HSD-1 and HSD-2) were found with similar activity in the placental cytosol on day 10 of pregnancy. The number of fetuses on day 10 of pregnancy was 15.4 and decreased significantly to 12.9 on day 12. The results suggested that expression of $20{\alpha}$-HSD in the placental tissues seems to be related the number of fetal survived in the specific time (days 11 and 12) which spontaneous fetal loss occurs.