• Title/Summary/Keyword: DNA Synthesis

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The Bacteriophage λ DNA Replication Protein P Inhibits the oriC DNA- and ATP-binding Functions of the DNA Replication Initiator Protein DnaA of Escherichia coli

  • Datta, Indrani;Sau, Subrata;Sil, Alok Kumar;Mandal, Mitai C.
    • BMB Reports
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    • v.38 no.1
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    • pp.97-103
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    • 2005
  • Under the condition of expression of $\lambda$ P protein at lethal level, the oriC DNA-binding activity is significantly affected in wild-type E. coli but not in the rpl mutant. In purified system, the $\lambda$ P protein inhibits the binding of both oriC DNA and ATP to the wild-type DnaA protein but not to the rpl DnaA protein. We conclude that the $\lambda$ P protein inhibits the binding of oriC DNA and ATP to the wild-type DnaA protein, which causes the inhibition of host DNA synthesis initiation that ultimately leads to bacterial death. A possible beneficial effect of this interaction of $\lambda$ P protein with E. coli DNA initiator protein DnaA for phage DNA replication has been proposed.

Efficacy evaluation on whitening cosmetics in Japan

  • Funasaka, Yoko
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.28 no.3
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    • pp.91-108
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    • 2002
  • Whitening agents are eagerly demanded especially by oriental women who often suffers from the pigmentary disorders such as melasma and solar lentigines. As these pigmentary disorders are exacerbated by ultraviolet (UV), the whitening agents could exert its effect not only by inhibiting melanin synthesis but also by inhibiting UV activated signals. Eumelanin protects UV-induced DNA damages so that the chemicals which could reduce UV-induced DNA damages might be the ideal lightening agents. The effect of newly synthesized antioxidants, a-tocopheryl ferulate, on protective effect for UV-induced DNA damages as well as inhibiting melanin synthesis are briefly shown. For clinical evaluation, our results of the efficacy of lightening agents on treating pigment macules in combination with chemical peeling are shown. Furthermore, newly developed facial image analyzers to quantitatively evaluate the improvement of pigment macules are introduced.

Influence of Panax Ginseng on DNA Synthesis of Submandibular Gland in Mice (고려인삼이 마우스의 악하선 DNA 합성능에 미치는 영향( I ))

  • Kwon, Y.C.;Chae, Y.B.;Chang, W.S.
    • The Korean Journal of Physiology
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    • v.8 no.1
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    • pp.23-26
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    • 1974
  • It was planned to evaluate the influence of Panax Ginseng upon DNA synthesis of submandibular gland in mice by observing incorporation of $[^3H]$ thymidine into the tissue cells. Thirty male mice $(body\;weight:\;18{\sim}20\;g)$ were divided equally into two groups. One group received every day (subcutaneously) 0. 05 ml/10 g body weight of ginseng extract(4 mg of ginseng alcohol extract in 1ml of saline), while !he other group received the same amount of saline, for 5 days. On the 5th experimental day, all animals received $1\;{\mu}Ci/g$ body weight of $[^3H]$ thymidine intraperitoneally 2 hours after the last medication. Five animals, at a time, of each group were sacrificed 1, 10, and 24 hours after $[^3H]$ thymidine administration, and the radioactivity of cells in their mandibular gland was measured autoradiographically in terms of the % number of radioactive cells in 1,000 tell counts (Radioactive Index, R.I.). It was found that the radioactive indices of mice that received ginseng were lower than the corresponding values of mice that received saline. The inference from the above result was that the ginseng suppressed DNA synthesis of cells in the mandibular gland.

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Cellular DNA Repair of Oxidative Deoxyribose Damage by Mammalian Long-Patch Base Excision Repair

  • Sung Jung-Suk;Son Mi-Young
    • Biomedical Science Letters
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    • v.11 no.2
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    • pp.103-108
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    • 2005
  • 2-Deoxyribonolactone (dL) arises as a major DNA damage induced by a variety of agents, involving free radical attack and oxidation of C1'-deoxyribose in DNA. We investigated whether dL lesions can be repaired in mammalian cells and the mechanisms underlying the role of DNA polymerase $\beta$ in processing of dL lesions. Pol $\beta$ appeared to be trapped by dL residues, resulting in stable DNA-protein cross-links. However, repair DNA synthesis at site-specific dL sites occurred effectively in cell-free extracts, but predominantly accompanied by long-patch base excision repair (BER) pathway. Reconstitution of long-patch BER demonstrated that FEN1 was capable of removing the displaced flap DNA containing a 5'-dL residue. Cellular repair of dL lesions was largely dependent on the DNA polymerase activity of Pol $\beta$. Our observations reveal repair mechanisms of dL and define how mammalian cells prevent cytotoxic effects of oxidative DNA lesions that may threaten the genetic integrity of DNA.

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Effects of 3-Aminobenzamide on DNA Strand Breaks and Excision Repair in CHO cells Exposed to Methyl Methanesulfonate and Ultraviolet-light (MMS와 자외선을 처리한 CHO세포에 있어서 DNA사 절단과 절제회복에 미치는 3-aminobenzamide의 영향)

  • Park, Sang-Dai;Jang, Young-Ju;Roh, Jung-Koo
    • The Korean Journal of Zoology
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    • v.26 no.3
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    • pp.171-179
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    • 1983
  • Amounts of DNA single strand breaks and unscheduled DNA synthesis in CHO cells exposed to MMS were increased in the presence of 3-aminobenzamide, a potent inhibitor of poly (ADP-ribose) polymerase. However, those in cells irradiated with UV-light were decreased. These results suggest that poly (ADP-ribose) polymerase acts negatively on the MMS-induced base excision repair but positively on the UV-induced nucleotide excision repair. In the combined treatment with MMS and UV-light in the presence of this inhibitor, amounts of strand breaks were just the same as those in the absence of the inhibitor. But those of unscheduled DNA synthesis were increased up to the amount induced by UV-light alone. These results may suggest that poly (ADP-ribose) polymerase affects the incision step of excision repair induced by MMS and UV-light independently, and that it may potentiate the complete cleaving of UV-induced pyrimidine dimers possibly by the repair enzymes which might have been partially inactivated by MMS.

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THE EFFECT OF DIFFERENTIAL MODULATION OF N-METHYL-D-ASPARTATE RECEPTOR ON THE PROLIFERATION OF PRIMARY CULTURED NORMAL HUMAN ORAL KERATINOCYTES: DNA SYNTHESIS RATE ANALYSIS (N-methyl-D-aspartate 수용기의 다양한 조절이 일차 배양된 정상사람구강각화세포의 증식에 미치는 영향; DNA 합성율 평가)

  • Kim, In-Soo;Paik, Ki-Suk;Chang, Mi-Sook;Lee, Won;Lee, Seung-Pyo
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.33 no.2
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    • pp.124-130
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    • 2007
  • In the present study, I investigated the effects of N-methyl-D-aspartate (NMDA), arachidonic acid (AA), and Nitric Oxide Synthase Inhibitor (NOSI), alone or in combination, on the proliferation of cultured primary normal human oral keratinocytes (NHOK). The purpose of this study was therefore the preliminary study for the examination of the interaction between these agents and NHOK in order to elucidate the mechanisms by which epithelial growth and regeneration are regulated. NHOK were obtained from gingival tissue of 20 individuals aged 20 to 29, and third passage (P3) cells were used for this study. The DNA synthesis was measured by the BrdU assay. Addition of low concentration of AA ($1{\mu}M$) and high concentration of AA with NMDA group (NMDA+AA $10{\mu}M$) made DNA synthesis rate increase significantly at the early stage. Adding NNA ($10{\mu}M$) affected DNA synthesis rate to increase significantly in 4 hours. At the early stage, DNA synthesis was significantly active in the NOS-I with NMDA groups than in the control and the NMDA-only group, while it didn't become statistically meaningful in 24 hours. AA $1{\mu}M$ and NNA $10{\mu}M$ may induce the proliferation of the NHOK independently and NOS-I may induce the proliferation of the NHOK with NMDA. These reactions might be related to the NMDA receptor in the cell and the change of the intracellular calcium ion concentration.

Effects of Radix Curcumae Aromaticae Extract in Rat Cardiac Endothelial Cells (울금 추출물이 배양 심장내피세포에 미치는 영향)

  • Kwon Kang Beom;Kim In Seob;Kim Hyun Gyu;Choi Ki Bang;Kim Yong Bok;Ryu Do Gon
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.17 no.1
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    • pp.71-76
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    • 2003
  • To test the protective effect of Radix Curcumae Aromaticae (RCA) on the damage of cardiac endothelial cells by xanthine oxidase (XO)/hypoxanthine (HX)-induced oxygen free radical, Neutral Red (NR), thiobarbituric acid reactive substances (TSARS), and DNA synthesis assay were used in the presence of RCA extract. The results of these experiments were obtained as follows ; Cardiac endothelial cells treated with XO/HX showed the cytotoxicity such as decreases in viability and DNA synthesis, a increase in lipid peroxidation. Cardiac endothelial cells pretreated with RCA extract protected the increase of lipid peroxidation by XO/HX. Cardiac endothelial cells pretreated with RCA extract inhibited the decrease of DNA synthesis by XO/HX. These results show that XO/HX elicits toxic effects in cultured cardiac endothelial cells derived from neonatal rat, and suggest that RCA extract is very effective in the prevention of XO/HX-induced toxicity.

Artificial Induction of Environmental Mammary Stress by Temperature and Micro-organism Causing Mastitis and Modulation of Mammary Growth by Adenosine, IGF-I and Prolatin In Vitro (In Vitro내 유선조직에의 인위적인 온도 및 유방염 발생 미생물에 의한 환경스트레스 유기와 Adenosine, IGF-I 및 Prolactin에 의한 성장조절작용)

  • 정석근;장병배;이창수;박춘근;홍병주;여인서
    • Korean Journal of Animal Reproduction
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    • v.21 no.4
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    • pp.325-333
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    • 1997
  • Recent evidence indicates that growth factors modulate response of mammary epithelial cells to environmental stress. The objective of this study was to examine the cellular and biochemical responses of mammary tissue to environmental stress caused by artificial mastitis. For experimental a, pp.oach, toxins of most mastitis causing organisms(Staph. aureus or Strep. agalactiae) and heat stress(42$^{\circ}C$) were artificially exposed to mammary tissue. Effects of these environmental stresses on cell growth, cell death and heat shock protein synthesis were examined. Lactating mammary tissure were cultured under basal medium(DMEM) su, pp.emented with insulin(10$\mu\textrm{g}$/ml) and aldosterone(1$\mu\textrm{g}$/ml). All treatment groups in heat stress at 42$^{\circ}C$ incubation significantly decreased DNA synthesis rates in comparison with those at 39$^{\circ}C$(P<0.05), however, these decreased DNAa synthesis rates were recovered by addition of adenosine(10$\mu$M) and IGFI(10ng/ml). Similar results were obtained when tissue growth rates were measured by DNA content/tissue. Strep. agalactiae toxin did not significantly decreased DNA content/tissue in comparison with no treatment of bacterial toxin with or without heat stress, however, tended to decrease DNA contents/tissue without heat stress. In the fluorography analysis, heat stress(42$^{\circ}C$ incubation) slightly increased 35S-methoionine labelled 70kd protein synthesis. These results indicate that environmental stress caused by artificial mastitis slightly decreased mammary growth or mammary size, however, these results could be recovered by addition of adenosine and IGF-I.

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GTP Induces S-phase Cell-cycle Arrest and Inhibits DNA Synthesis in K562 Cells But Not in Normal Human Peripheral Lymphocytes

  • Moosavi, Mohammad Amin;Yazdanparast, Razieh;Lotfi, Abbas
    • BMB Reports
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    • v.39 no.5
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    • pp.492-501
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    • 2006
  • Since differentiation therapy is one of the promising strategies for treatment of leukemia, universal efforts have been focused on finding new differentiating agents. In that respect, we used guanosine 5'-triphosphate (GTP) to study its effects on K562 cell line. GTP, at concentrations between 25-200 ${\mu}M$, inhibited proliferation (3-90%) and induced 5-78% increase in benzidine-positive cells after 6-days of treatments of K562 cells. Flow cytometric analyses of glycophorine A (GPA) showed that GTP can induce expression of this marker in more mature erythroid cells in a time- and dose-dependent manner. These effects of GTP were also accompanied with inhibition of DNA synthesis (measured by [$^3H$]-thymidine incorporation) and early S-phase cell cycle arrest by 96 h of exposure. In contrast, no detectable effects were observed when GTP administered to unstimulated human peripheral blood lymphocytes (PBL). However, GTP induced an increase in proliferation, DNA synthesis and viability of mitogen-stimulated PBL cells. In addition, growth inhibition and differentiating effects of GTP were also induced by its corresponding nucleotides GDP, GMP and guanosine (Guo). In heat-inactivated medium, where rapid degradation of GTP via extracellular nucleotidases is slow, the anti-proliferative and differentiating effects of all type of guanine nucleotides (except Guo) were significantly decreased. Moreover, adenosine, as an inhibitor of Guo transporter system, markedly reduced the GTP effects in K562 cells, suggesting that the extracellulr degradation of GTP or its final conversion to Guo may account for the mechanism of GTP effects. This view is further supported by the fact that GTP and Guo are both capable of impeding the effects of mycophenolic acid. In conclusion, our data will hopefully have important impact on pharmaceutical evaluation of guanine nucleotides for leukemia treatments.

Onset of Pronuclear Formation and DNA Synthesis in Porcine Oocytes following Intracytoplasmic Injection of Porcine or Murine Spematozoa

  • Kim, N. H.;Cui, X. S;Kim, B. K .;S. H. Jun;D. I. Jin;Lee, S. H.;Park, C. S.
    • Korean Journal of Animal Reproduction
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    • v.26 no.4
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    • pp.361-368
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    • 2002
  • The onset of pronucleus formation and DNA synthesis in porcine oocytes following the injection of porcine or murine sperm was determined in order to obtain insights into species-specific paternal factors that contribute to fertilization. After 44h in vitro maturation, spermatozoa was injected into the cytoplasm of oocytes. After injection, all oocytes were transferred to NCSU23 medium and cultured at 39'E under 5% CO2 in air. Similar frequencies of oocytes with female pronuclei were observed after injection with porcine sperm or with murine sperm. In contrast, male pronuclei formed 8 to 9 h following the injection of porcine sperm, and 6 to 8 h following the injection of murine sperm. After pronucleus formation maternally derived microtubules were assembled and appeared to move both male and female pronuclei to the oocyte center. A few porcine oocytes entered metaphase 22 h after the injection of murine sperm, but normal cell division was not observed. The mean time of onset of S-phase in male pronuclei was 9.7 h following porcine sperm injection and 7.4 h following mouse sperm injection. These results suggested that DNA synthesis was delayed in both pronuclei until the sperm chromatin fully decondensed, and the sperm nuclear decondensing activity and microtubule nucleation abilities of the male centrosome are cell cycle dependent.