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Travis Walton, Jack W Szostak
The nonenzymatic polymerization of RNA may have enabled copying of functional sequences during the origin of life. Recent progress utilizing 5'-phosphoro-2-aminoimidazole activation has reinvigorated the possibility of using nonenzymatic RNA polymerization for copying arbitrary sequences. However, the reasons why 2-aminoimidazole (AI) is a superior activation group remain unclear. Here we report that the predominant mechanism of polymerization using cytidine-5'-phosphoro-2-aminoimidazolide (Cp*) involves a 2-aminoimidazolium-bridged dinucleotide (Cp*pC) intermediate...
October 31, 2017: Biochemistry
Guobin Mao, Qin Cai, Fubing Wang, Changliang Luo, Xinghu Ji, Zhike He
As the blood glucose concentration is an important clinical parameter of diabetes, the rapid and effective detection of blood glucose is very significant for monitoring and managing diabetes. Here, a facile method to prepare Rox-DNA functionalized CdZnTeS quantum dots (QDs) was developed. The Rox-DNA functionalized CdZnTeS QDs were prepared by a one-pot hydrothermal method through phosphorothioate DNA bound to QDs, which were employed as a ratiometric fluorescent probe for the rapid and sensitive detection of H2O2 and glucose...
November 7, 2017: Analytical Chemistry
Saikat Bala, Jen-Yu Liao, Hui Mei, John C Chaput
α-l-Threofuranosyl nucleic acid (TNA) is an artificial genetic polymer composed of vicinal 2',3'-phosphodiester bonds linking adjacent threofuranosyl nucleosides. TNA is one of a small number of genetic polymers that are both highly resistant to nuclease digestion and capable of cross-pairing with DNA and RNA. Although an efficient method for synthesizing TNA nucleosides has been reported, very few advances have been made in the synthesis of phosphorylated TNA compounds. Here, we describe a highly efficient method for synthesizing α-l-threofuranosyl nucleoside 3'-monophosphates (tNMPs), 3'-phosphoro(2-methyl)imidazolides (2-MeImptNs), and 3'-triphosphates (tNTPs) bearing the four genetic bases of adenine (A), cytosine (C), thymine (T), and guanine (G)...
May 19, 2017: Journal of Organic Chemistry
Wen Zhang, Chun Pong Tam, Jiawei Wang, Jack W Szostak
Many high-resolution crystal structures have contributed to our understanding of the reaction pathway for catalysis by DNA and RNA polymerases, but the structural basis of nonenzymatic template-directed RNA replication has not been studied in comparable detail. Here we present crystallographic studies of the binding of ribonucleotide monomers to RNA primer-template complexes, with the goal of improving our understanding of the mechanism of nonenzymatic RNA copying, and of catalysis by polymerases. To explore how activated ribonucleotides recognize and bind to RNA templates, we synthesized an unreactive phosphonate-linked pyrazole analogue of guanosine 5'-phosphoro-2-methylimidazolide (2-MeImpG), a highly activated nucleotide that has been used extensively to study nonenzymatic primer extension...
December 28, 2016: ACS Central Science
Enver Cagri Izgu, Seung Soo Oh, Jack W Szostak
We present a scalable synthesis of 3'-amino-3'-deoxy-2-thio-thymidine-5'-phosphoro-2-methylimidazolide, an activated monomer that can copy adenosine residues in nucleic acid templates rapidly without a polymerase. The sulfur atom substitution enhances the rate of template copying by 5-fold compared with the 3'-amino-3'-deoxy-T monomer, while the 3'-amino monomers exhibit a 2- to 30-fold enhancement compared with their ribonucleotide counterparts.
March 4, 2016: Chemical Communications: Chem Comm
Samer Habash, Luma Al-Banna
The efficacy of the phosphonate fertilizers, Calphos(®) (a.i. calcium phosphonate), Magphos(®) (a.i. magnesium phosphonate and potassium phosphonate) and Phosphoros(®) (a.i. potassium phosphonate) against two species of root knot nematodes (RKN), Meloidogyne javanica and M. incognita is evaluated. Laboratory experiments showed that Calphos(®), Magphos(®) and their main components inhibited egg hatching and caused 100% mortality of the second stage juveniles (J2s) of the two RKN species; the hatching inhibition effects persisted after transferring the egg masses of both species to water...
June 2011: Journal of Nematology
Cordula Weber, Christian Müller, Anja Podszuweit, Carmen Montino, Jörg Vollmer, Alexandra Forsbach
The Toll-like receptors (TLRs) 3, 7, 8 and 9 stimulate innate immune responses upon recognizing pathogen-derived nucleic acids. TLR3 is located on the cell surface and in cellular endosomes and recognizes double-stranded viral RNA or the synthetic mimic poly rI:rC. Recently, unformulated small interfering RNA (siRNA) has been reported as ligand for surface-expressed murine TLR3. Blockage of TLR3 is achieved by single-stranded DNA. We confirm and expand the observation that poly rI:rC-mediated TLR3 immune activation is blocked in a sequence-, length-, backbone- and CpG-dependent manner...
May 2012: Immunology
Nidaa A Othman, Michael Gallacher, Tarek Z Deeb, Daniel T Baptista-Hon, David C Perry, Tim G Hales
Picrotoxin and t-butylbicyclophosphorothionate (TBPS) are GABA(A) receptor (GABA(A)R) open channel blockers. However, picrotoxin displaceable [(35)S]TBPS binding to α1β2γ2 GABA(A)Rs occurs in the absence of GABA, suggesting that access to the binding site is independent of activation. Alternatively, spontaneous gating may provide access to the channel. In the absence of episodic GABA application, picrotoxin and TBPS blocked (by 91 ± 3% and 85 ± 5%, respectively) GABA-evoked currents mediated by α1β2γ2 receptors...
January 1, 2012: Journal of Physiology
Muhammad Dawood Shah, Mohammad Iqbal
Diazinon (O,O-diethyl-O-[2-isopropyl-6-methyl-4-pyrimidinyl] phosphoro thioate), an organo-phosphate insecticide, has been used worldwide in agriculture and domestic for several years, which has led to a variety of negative effects in non target species including humans. However, its nephrotoxic effects and mechanism of action has not been fully elucidated so far. Therefore, the present study was aimed at evaluating the nephrotoxic effects of diazinon and its mechanism of action with special reference to its possible ROS generating potential in rats...
December 2010: Food and Chemical Toxicology
Angelo C Djihinto, André Katary, Patrick Prudent, Jean-Michel Vassal, Maurice Vaissayre
Pyrethroid resistance in Helicoverpa armigera (Hübner) field populations was investigated in Benin over several years by using third- and fourth-instar larval topicalbioassays. H. armigera was resistant to pyrethroids tested as cypermethrin, deltamethrin, bifenthrin, and fenvalerate. Pretreatment with piperonyl butoxide significantly decreased the LD50 value of cypermethrin and deltamethrin, and the resistance suppression by this synergist effect was observed. No significant decrease in the LD50 value was obtained when S,S,S-tributyl phosphoro-trithioate was applied before deltamethrin...
October 2009: Journal of Economic Entomology
Monica Bellozas Reinhard, Susana Arnstein de Licastro
R,R'-disubstituted sulfoximines were phosphorylated with O,O-diethylchloro phosphate and phosphorothionate to obtain new organophosphorus compounds. After purification they were characterized by GC-MS and (1)H-NMR. The toxicity of the synthesized O,O-diethyl N-(R,R'-disubstituted sulfoximine) phosphoro-amidothionates was assayed on Musca domestica. It was found that the methyl phenyl derivative was the most toxic compound, followed by the dipropyl and dibutyl derivatives. The dihexyl compound was the less toxic of all the assayed compounds, being one hundred times less toxic than a paraoxon standard The anticholinesterasic activity of the corresponding phosphoramidates was assayed on homogenates of house flies' heads, giving values similar to paraoxon for the methyl phenyl derivative...
2005: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Bingzi Chen, Xinfeng Zhou, Koli Taghizadeh, Jingyang Chen, JoAnne Stubbe, Peter C Dedon
DNA oxidation plays a substantive role in the pathophysiology of human diseases, such as cancer. While the chemistry of nucleobase lesions has dominated studies of DNA damage, there is growing evidence that the oxidation of 2-deoxyribose in DNA plays a critical role in the genetic toxicology of oxidative stress. As part of an effort to define the spectrum of 2-deoxyribose oxidation products arising in vitro and in vivo, we now describe methods for quantifying products arising from 4' oxidation of 2-deoxyribose in DNA...
November 2007: Chemical Research in Toxicology
Chunyan Li, Xiaosong Cheng, Hongchi Jiang, Xueying Sun
Angiogenesis plays a key role in the growth and metastasis of lung cancers, and vascular endothelial growth factor (VEGF) is one of the major angiogenic factors. The study aims to investigate whether phosphoro thioate-modified antisense VEGF oligodeoxynucleo tides (ASODN) formulated in cationic liposome could inhibit the growth of Lewis lung carcinoma (LLC) tumors by antiangiogenesis. The study demonstrated that ASODN downregulated the expression of VEGF in LLC cells at levels of protein and mRNA in vitro and in vivo...
2006: Tumour Biology: the Journal of the International Society for Oncodevelopmental Biology and Medicine
Jacqueline Idinger, Tamara Coja, Sylvia Blümel
Both lethal and sublethal effects of the benzoxazoid 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA), the degradation products 6-methoxy-benzoxazolin-2(3H)-one (MBOA), 2-amino-7-methoxy-(3H)-phenoxazin-3-one (AMPO), and 2-acetylamino-7-methoxy-3(H)-phenoxazin-3-one (AAMPO) and the structure-related compounds 2-methoxy-N-(2-oxo-1,3-oxazolidin-3yl)acet-2'=6'-xylidide (oxadixyl), and O,O-diethyl S-[6-chloro-2-oxobenzoxazolin-3-yl)methyl]phosphorodithioate (phosalone) on the collembola Folsomia candida and on the carabid beetle Poecilus cupreus (except phosalone) were determined...
September 2006: Ecotoxicology and Environmental Safety
Wang Hao, Wu Xing-Jun, Cui Yong-Yao, Zhu Liang, Lu Yang, Chen Hong-Zhuan
Loss of cholinergic neurons along with muscarinic acetylcholine receptors (mAChRs) in cerebral cortex and hippocampus is closely associated with Alzheimer's disease (AD). Recent drug development for AD treatment focuses heavily on identifying M(1) receptor agonists. However, mAChRs undergo down-regulation in response to agonist-induced sustained activation. Therefore, therapeutic effectiveness wanes during continuous use. Thus, another potentially effective approach, which overcomes this drawback is to develop compounds, which instead up-regulate M(1) receptor expression...
July 22, 2005: Neuroscience Letters
Brenda Eskenazi, Kim Harley, Asa Bradman, Erin Weltzien, Nicholas P Jewell, Dana B Barr, Clement E Furlong, Nina T Holland
Although pesticide use is widespread, little is known about potential adverse health effects of in utero exposure. We investigated the effects of organophosphate pesticide exposure during pregnancy on fetal growth and gestational duration in a cohort of low-income, Latina women living in an agricultural community in the Salinas Valley, California. We measured nonspecific metabolites of organophosphate pesticides (dimethyl and diethyl phosphates) and metabolites specific to malathion (malathion dicarboxylic acid), chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphoro-thioate], and parathion (4-nitrophenol) in maternal urine collected twice during pregnancy...
July 2004: Environmental Health Perspectives
No abstract text is available yet for this article.
February 7, 1959: Nature
No abstract text is available yet for this article.
January 1958: Rozhledy V Chirurgii: Měsíčník Československé Chirurgické Společnosti
A A Horner, G F Widhopf, J A Burger, K Takabayashi, N Cinman, A Ronaghy, H L Spiegelberg, E Raz
BACKGROUND: Immunostimulatory sequence oligodeoxynucleotide (ISS-ODN) is a potent antiallergic immunomodulating agent in mice. However, few studies have addressed its antiallergic potential in human subjects. OBJECTIVE: We sought to determine whether a phosphoro-thioate ISS-ODN could inhibit IL-4-dependent IgE synthesis by human B cells. METHODS: Initially, nonatopic- and atopic-donor PBMCs were incubated with ISS-ODN or mutated oligodeoxynucleotide, and cytokine production and B-cell expression of IFN-gamma receptor and IL-4 receptor were measured by using ELISA and flow cytometry, respectively...
September 2001: Journal of Allergy and Clinical Immunology
I A Kozlov, L E Orgel
The template-directed oligomerization of nucleoside-5'-phosphoro-2-methyl imidazolides on standard oligonucleotide templates has been studied extensively. Here, we describe experiments with templates in which inosinic acid (I) is substituted for guanylic acid, or 2,6-diaminopurine nucleotide (D) for adenylic acid. We find that the substitution of I for G in a template is strongly inhibitory and prevents any incorporation of C into internal positions in the oligomeric products of the reaction. The substitution of D for A, on the contrary, leads to increased incorporation of U into the products...
November 1999: Helvetica Chimica Acta
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