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101.
102.
A novel fluorometric oligonucleotide
assay to measure O 6-methylguanine DNA
methyltransferase, methylpurine DNA glycosylase, 8-oxoguanine DNA glycosylase
and abasic endonuclease activities: DNA repair status in human breast
carcinoma cells overexpressing methylpurine DNA glycosylase 总被引:3,自引:0,他引:3 下载免费PDF全文
Emiko L. Kreklau Melissa Limp-Foster Naili Liu Yi Xu Mark
R. Kelley Leonard C. Erickson 《Nucleic acids research》2001,29(12):2558-2566
DNA repair status plays a major role in mutagenesis, carcinogenesis and resistance to genotoxic agents. Because DNA repair processes involve multiple enzymatic steps, understanding cellular DNA repair status has required several assay procedures. We have developed a novel in vitro assay that allows quantitative measurement of alkylation repair via O6-methylguanine DNA methyltransferase (MGMT) and base excision repair (BER) involving methylpurine DNA glycosylase (MPG), human 8-oxoguanine DNA glycosylase (hOGG1) and yeast and human abasic endonuclease (APN1 and APE/ref-1, respectively) from a single cell extract. This approach involves preparation of cell extracts in a common buffer in which all of the DNA repair proteins are active and the use of fluorometrically labeled oligonucleotide substrates containing DNA lesions specific to each repair protein. This method enables methylation and BER capacities to be determined rapidly from a small amount of starting sample. In addition, the stability of the fluorometric oligonucleotides precludes the substrate variability caused by continual radiolabeling. In this report this technique was applied to human breast carcinoma MDA-MB231 cells overexpressing human MPG in order to assess whether up-regulation of the initial step in BER alters the activity of selected other BER (hOGG1 and APE/ref-1) or direct reversal (MGMT) repair activities. 相似文献
103.
104.
The unicellular green algae Chlorella ellipsoidea was used tostudy transient changes in the energy state of adenylates andthe redox states of pyridine nucleotides induced by environmentalchanges. The transition from anaerobic to aerobic conditionsin the dark induced a sharp rise in the ATP ratio [ATP/(ATP+ADP+AMP)],a sudden decrease in the NADH ratio [NADH/(NAD++NADPH)] anda transient drop in the NADPH ratio [NADPH/(NADP++NADPH)]. Illuminationafter a dark period under anaerobic, CO2-free conditions inducedsharp increases in the ATP and NADPH ratios and a slower decreasein the NADH ratio. Illumination under aerobic conditions, ineither the presence or absence of CO2, caused a sharp increasein the NADPH ratio, a small increase in the ATP ratio and aslower increase in the NADH ratio. In the presence of CO2, asubsequent large drop in the NADPH ratio occurred. Darkeningunder anaerobic, CO2-free conditions induced a sudden decreasein the ATP ratio, a temporary fall in the NADPH ratio and aslow increase in the NADH ratio. Darkening under aerobic conditionsinduced transient drops in the ATP and NADPH ratios and a suddendrop in the NADH ratio. The addition of CO2 to the atmospherewith illumination produced a decrease in all three parameters. These results are discussed in relation to current theoriesof the interaction between photosynthesis and respiration. Ourobservations indicate that the energy and reducing potentialsgenerated by photochemical processes are used for and controlother processes besides CO2 fixation in photosynthetic cells. (Received December 3, 1981; Accepted May 4, 1982) 相似文献
105.
Regulation of thymidine kinase (TK) activity was examined in L(O)c133 and L(H3) cells carrying varicella-zoster virus-TK gene. TK activity of L(O)c133 cells was similarly high in either medium but that of L(H3) cells was high in HAT medium and low in non-HAT medium. Cell growth was well correlated with TK activities of L(O)c133 and L(H3) cells in medium conditions. Regulation of the TK gene in L cells carrying the VZV-TK gene is discussed. 相似文献
106.
107.
Min-Kyoo Shin Edwin Vázquez-Rosa Yeojung Koh Matasha Dhar Kalyani Chaubey Coral J. Cintrón-Pérez Sarah Barker Emiko Miller Kathryn Franke Maria F. Noterman Divya Seth Rachael S. Allen Cara T. Motz Sriganesh Ramachandra Rao Lara A. Skelton Machelle T. Pardue Steven J. Fliesler Chao Wang Andrew A. Pieper 《Cell》2021,184(10):2715-2732.e23
108.
109.
Yuzo Azuma Katsuzi Kawamura Hiroshi Isogai Emiko Isogai 《Microbiology and immunology》1993,37(4):325-329
A 2-year-old mongrel dog developed neurological signs following tick bite. These included astasia, persistent tonic convulsions and hyper-reflexia. Both serum IgG and IgM antibody titers against Borrelia burgdorferi were positive in enzyme-linked immunosorbent assay (ELISA). The neurological signs subsided after high-dose penicillin and streptomycin treatment. A strain of spirochetes (P427a) was isolated from the midgut of Ixodes persulcatus feeding on the dog. Morphological characteristic, immunological property and protein profile revealed that the isolate was B. burgdorferi. Similarly, a 2-year-old Labrador retriever dog developed neurological signs after tick bite and showed a positive IgG antibody titer against B. burgdorferi. Antibiotic treatment was effective also in this case. These findings suggest that neurological symptoms shown in both dogs were caused by infection with B. burgdorferi. 相似文献
110.
Emiko Nishi Nami Suzuki-Hashido Takashi Hayakawa Yamato Tsuji Bambang Suryobroto Hiroo Imai 《Primates; journal of primatology》2018,59(6):523-530
For many primates, sweet taste is palatable and is an indicator that the food contains carbohydrates, such as sugars and starches, as energy sources. However, we have found that Asian colobine monkeys (lutungs and langurs) have low sensitivity to various natural sugars. Sweet tastes are recognized when compounds bind to the sweet taste receptor TAS1R2/TAS1R3 in the oral cavity; accordingly, we conducted a functional assay using a heterologous expression system to evaluate the responses of Javan lutung (Trachypithecus auratus) TAS1R2/TAS1R3 to various natural sugars. We found that Javan lutung TAS1R2/TAS1R3 did not respond to natural sugars such as sucrose and maltose. We also conducted a behavioral experiment using the silvery lutung (Trachypithecus cristatus) and Hanuman langur (Semnopithecus entellus) by measuring the consumption of sugar-flavored jellies. Consistent with the functional assay results for TAS1R2/TAS1R3, these Asian colobine monkeys showed no preference for sucrose or maltose jellies. These results demonstrate that sweet taste sensitivity to natural sugars is low in Asian colobine monkeys, and this may be related to the specific feeding habits of colobine monkeys. 相似文献