Articles de revues : « Amanitine »

1

Kubicka, Magdalena, Joanna Wilk, Paweł Dębiec, Krystian Cholewa, Magdalena Makarewicz et Adrianna Szymańska. « Amanitine poisoning - cases, management, therapy results ». Journal of Education, Health and Sport 13, n^o 4 (1 mars 2023) : 276–80. http://dx.doi.org/10.12775/jehs.2023.13.04.032.

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Mushroom poisoning continues to be a serious clinical problem. The most serious are intoxications with mushrooms containing cytotropic toxins with predominant injury of liver, kidneys and heart. The toxic properties of the phalloides are mainly due to α-amanitin, which is an inhibitor of RNA polymerase II. The clinical course of poisoning can be divided for 4 periods. The asymptomatic period usually lasts 6-24 hours after mushroom consumption. Then the period of the gastrointestinal disorder lasting on average 12-24 hours. The second latency period with apparent improvement of the patient's general condition lasting 12-24 hours is subjected to the stage, during which biochemical markers of hepatocyte activity appear. After a few days (usually on the 4-5th day) from poisoning, kidney function may occur (oliguria or anuria), and circulatory system disorders may also occur. Death usually occurs between 4-16 days after poisoning. The treatment of poisoning with amanita phalloides includes a number of procedures, including rapid removal of toxins, blocking the penetration of amatoxins into the hepatic cell, compensation of systemic metabolic disorders, and extracorporeal support of liver function.

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Mydlík, M. « Haemoperfusion of Alfa Amanitine -- In Vitro Study ». Toxicology Letters 78 (août 1995) : 59. http://dx.doi.org/10.1016/03784-2749(59)4855b-.

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Gicquel, T., S. Lepage, O. Tribut, B. Duretz et I. Morel. « O44 : Dosage des amatoxines (α-amanitine, β-amanitine) et de la phalloidine dans les urines par LC-HR-MS ». Toxicologie Analytique et Clinique 26, n^o 2 (juin 2014) : S25—S26. http://dx.doi.org/10.1016/s2352-0078(14)70052-6.

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Vlaskin, D. N., E. T. Gainullina, O. V. Klyuster, I. V. Rybal’chenko, S. B. Ryzhikov et V. F. Taranchenko. « Express method for detection of Amanita phalloides amanitine toxins ». Bulletin of Experimental Biology and Medicine 141, n^o 1 (janvier 2006) : 110–11. http://dx.doi.org/10.1007/s10517-006-0107-2.

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Schenk, M., S. Rubitschek, C. Thiel, K. Knubben, M. M. Morgalla, A. Etspüler et A. Königsrainer. « AMANITINE INTOXICATION IN A PORCINE MODEL : WHEN TRANSPLANT, WHEN WAIT FOR REGENERATION ? » Transplantation 86, Supplement (juillet 2008) : 198. http://dx.doi.org/10.1097/01.tp.0000332246.68047.7d.

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Muraoka, Shinjiro, Nobuko Fukamachi, Kiyohisa Mizumoto et Takao Shinozawa. « Detection and Identification of Amanitins in the Wood-Rotting Fungi Galerina fasciculata andGalerina helvoliceps ». Applied and Environmental Microbiology 65, n^o 9 (1 septembre 1999) : 4207–10. http://dx.doi.org/10.1128/aem.65.9.4207-4210.1999.

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ABSTRACT More than 600 strains of wood-rotting fungi were screened for the detection of amanitins. Three strains of Galerina fasciculata and 18 strains of Galerina helvolicepscontained amanitins. These strains contained mainly α- and β-amanitins in the native fruit bodies, while α- and γ-amanitins were found in liquid-cultured mycelia. Purified amanitins were confirmed by their chromatographic profiles, spectra (UV, Fourier transform infrared, and atmospheric ionization mass), cytotoxicity for mammalian cell lines (3T3 and SiHa), and inhibitory effects on RNA polymerase II. The results revealed that the purified amanitin fractions from these species are identical to authentic amanitins and suggest that these two species must be handled as poisonous mushrooms.

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Feigel, Bartłomiej, ariusz Zuba et Wojciech Lechowicz. « Screening method for the analysis of blood and urine for the presence of naturally occurring toxic compounds from mushrooms (fungi) using the LC-MS method ». Problems of Forensic Sciences, n^o 126-127 (29 mars 2022) : 137–51. http://dx.doi.org/10.4467/12307483pfs.20.008.15448.

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Analysis of biological material collected during autopsies and even from living humans for the presence of amanitins and other fungal toxins remains a challenge in forensic toxicology. A qualitative method for the detection of α-amanitin, β-amanitin, γ-amanitin, muscarine, and psilocin in blood and urine has been developed. To achieve this goal, solid phase extraction HLB 3cc 60mg columns were used. Blood and urine samples were purified with water and aqueous methanol solution, and then extracted with acetonitrile. An LC/QTOF system equipped with a C18 column was applied to identify the analytes. Acetonitrile and water with formic acid were utilized as mobile phases. The developed method was validated. The detection limits for α-amanitin, β-amanitin, γ-amanitin, muscarine and psilocin are, respectively, 1.4 ng/ml, 0.3 ng/ml, 1.2 ng/ml, 1.8 ng/ml, and 0.3 ng/ml in blood, and 1.5 ng/ml, 2.1 ng/ml, 1.5 ng/ml, 1.6 ng/ml, and 1.1 ng/ml in urine. The developed method allows for efficient, qualitative identification of all the above-mentioned compounds in a toxicological laboratory.

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Flammer, René, et Katharina M. Schenk-Jäger. « Pilzvergiftungen – die Schattenseiten des Myzetismus ». Therapeutische Umschau 66, n^o 5 (1 mai 2009) : 357–64. http://dx.doi.org/10.1024/0040-5930.66.5.357.

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Die meisten Pilzvergiftungen manifestieren sich innerhalb von 12 Stunden mit Brechdurchfällen. Sie lassen sich grob in Ereignisse mit kurzer (< 4h) und langer Latenz (> 4h) einteilen. In der Regel muss bei langen Latenzzeiten (meistens 8 - 12 - 18h) ein Phalloides-Syndrom erwogen werden, besonders nach Verzehr unkontrollierter Wildpilze. Kürzere Latenzzeiten schließen jedoch eine Amatoxin-Vergiftung nicht aus. Denn üppige Mahlzeiten der auch an Chitin reichen Pilze, Mischgerichte und individuelle Faktoren verkürzen gelegentlich die Latenzzeit und verschleiern eine Amatoxinvergiftung. Deshalb ist jeder Brechdurchfall nach Pilzgenuss bis zum Gegenbeweis verdächtig auf eine Vergiftung durch amanitinhaltige Pilze. Wenn sich die Ursache der Beschwerden nicht innerhalb einer halben Stunde unter Beizug mykologischer Assistenz klären lässt, muss das Phalloides-Programm aktiviert werden. In der Zwischenzeit werden noch vorhandene Pilzfragmente im Abfall, in Mahlzeitenresten und Erbrochenem analysiert (Sporenanalyse) und der Urin auf Amanitine (ELISA) untersucht. Mit dem Grundsatz “Therapie vor Diagnose“ dürfte sich die Mortalität der Knollenblätterpilzvergiftung von aktuell etwa 5% weiter senken lassen. Die aktuellen Therapieprogramme vermittelt das Schweizerische Toxikologische Informationszentrum (Tel. 145), ebenso die Adressen der speziell für Notfälle ausgebildeten Pilzfachleute, die auch unter www.vapko.ch aufgelistet sind. Von den 18 Vergiftungssyndromen stellen wir die in der Schweiz häufigsten und wichtigsten vor. In der Übersicht sind die anderen Syndrome mit aufgeführt. Realtiv häufig sind das Gastrointestinale Frühsyndrom mit Latenz < 4h und die Indigestion mit variabler Latenzzeit von 1–20h. Rauschzustände nach Genuss von Fliegen- und Pantherpilzen sind selten. Hingegen ist Psychodelie nach Genuss von Psilocyben häufig, wobei nur ausnahmsweise ärztliche Hilfe beansprucht wird. Bei Spätmanifestationen nach Tagen wie Nierenversagen oder Rhabdomyolyse empfiehlt sich die Frage nach mykophagen Gewohnheiten. Nur so wird man einem Orellanus- oder Equestre-Syndrom auf die Spur kommen. Pilze im Hausgarten verlocken Kinder oft zum Spielen und kleinen Kostproben. Wie soll man sich verängstigten Eltern gegenüber verhalten? Wie groß ist das toxikologische Potential der Pilze in den Gärten? Wir diskutieren die Optionen.

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Rėkutė, Skirmantė, Marius Miglinas et Laurynas Rimševičius. « DAŽNIAUSI APSINUODIJIMO GRYBAIS SINDROMAI IR INKSTŲ PAŽEIDIMAI ». Medicinos teorija ir praktika 22, n^o 3 (2 janvier 2017) : 213–17. http://dx.doi.org/10.15591/mtp.2016.033.

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Reikšminiai žodžiai: grybai, apsinuodijimai, amanitinas, orelaninas, inkstai. Apsinuodijimas grybais yra reta ūminių inkstų ir kepenų pažeidimų priežastis, tačiau gali sukelti rimtų sveikatos sutrikimų ir baigtis mirtimi. Lietuvoje dažniausiai apsinuodijama musmirėmis (Amanita genties grybais) ir nuodingaisiais nuosėdžiais (Cortinarius orellanus), kurie atitinkamai sukelia Amanitino ir Orelano sindromus. Užsienyje nustatyta rabdomiolizės sukeltų mirties atvejų apsinuodijus nuodingąja ūmėde (Russula subnigricans). Apsinuodijus grybais, atsiranda ankstyvųjų simptomų – pykinimas, vėmimas, viduriavimas, arba vėlyvųjų – negrįžtamų inkstų ir kepenų pažeidimų, elektrolitų disbalansas, kvėpavimo ir kardiovaskulinės sistemos pokyčių. Intoksikacijos veikimo mechanizmas siejamas su DNR bei RNR sintezės inhibicija, oksidaciniais ląstelės pažeidimais. Lietuvoje diagnozė remiasi klinika ir surinkta anamneze, užsienyje atliekama inkstų biopsija ir ieškoma histologinių pokyčių. Specifinio gydymo nėra. Efektyviausias gydymas – palaikomasis: agresyvus skysčių atstatymas, elektrolitų balanso palaikymas, gyvybiškai svarbių funkcijų stabilizavimas. Sunkiais atvejais atliekama inkstų ar/ ir kepenų transplantacija. Norint apsaugoti save ir aplinkinius nuo apsinuodijimo grybais, svarbu atpažinti valgomus grybus, tinkamai apdoroti prieš valgant bei riboti vartojamų grybų kiekį.

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Bever, Candace S., Kenneth D. Swanson, Elizabeth I. Hamelin, Michael Filigenzi, Robert H. Poppenga, Jennifer Kaae, Luisa W. Cheng et Larry H. Stanker. « Rapid, Sensitive, and Accurate Point-of-Care Detection of Lethal Amatoxins in Urine ». Toxins 12, n^o 2 (15 février 2020) : 123. http://dx.doi.org/10.3390/toxins12020123.

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Globally, mushroom poisonings cause about 100 human deaths each year, with thousands of people requiring medical assistance. Dogs are also susceptible to mushroom poisonings and require medical assistance. Cyclopeptides, and more specifically amanitins (or amatoxins, here), are the mushroom poison that causes the majority of these deaths. Current methods (predominantly chromatographic, as well as antibody-based) of detecting amatoxins are time-consuming and require expensive equipment. In this work, we demonstrate the utility of the lateral flow immunoassay (LFIA) for the rapid detection of amatoxins in urine samples. The LFIA detects as little as 10 ng/mL of α-amanitin (α-AMA) or γ-AMA, and 100 ng/mL of β-AMA in urine matrices. To demonstrate application of this LFIA for urine analysis, this study examined fortified human urine samples and urine collected from exposed dogs. Urine is sampled directly without the need for any pretreatment, detection from urine is completed in 10 min, and the results are read by eye, without the need for specialized equipment. Analysis of both fortified human urine samples and urine samples collected from intoxicated dogs using the LFIA correlated well with liquid chromatography–mass spectrometry (LC-MS) methods.

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Lee, Jiyu, Byeong ill Lee, Jangmi Choi, Yuri Park, Seo-Jin Park, Minjae Park, Jeong-Hyeon Lim, Sangsoo Hwang, Jeong-Min Lee et Young G. Shin. « Investigation of In Vitro and In Vivo Metabolism of α-Amanitin in Rats Using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometric Method ». Molecules 27, n^o 23 (6 décembre 2022) : 8612. http://dx.doi.org/10.3390/molecules27238612.

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The purpose of this study is to investigate the difference of in vitro–in vivo correlation of α-amanitin from clearance perspectives as well as to explore the possibility of extra-hepatic metabolism of α-amanitin. First, a liquid chromatography-quadrupole-time-of-flight-mass spectrometric (LC-qTOF-MS) method for α-amanitin in rat plasma was developed and applied to evaluate the in vitro liver microsomal metabolic stability using rat and human liver microsomes and the pharmacokinetics of α-amanitin in rat. The predicted hepatic clearance of α-amanitin in rat liver microsomes was quite low (5.05 mL/min/kg), whereas its in vivo clearance in rat (14.0 mL/min/kg) was close to the borderline between low and moderate clearance. To find out the difference between in vitro and in vivo metabolism, in vitro and in vivo metabolite identification was also conducted. No significant metabolites were identified from the in vivo rat plasma and the major circulating entity in rat plasma was α-amanitin itself. No reactive metabolites such as GSH-adducts were detected either. A glucuronide metabolite was newly identified from the in vitro liver microsomes samples with a trace level. A semi-mass balance study was also conducted to understand the in vivo elimination pathway of α-amanitin and it showed that most α-amanitin was mainly eliminated in urine as intact which implies some unknown transporters in kidney might play a role in the elimination of α-amanitin in rat in vivo. Further studies with transporters in the kidney would be warranted to figure out the in vivo clearance mechanism of α-amanitin.

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Xu, Song, Jiean Tan, Xiaojuan Chen, Xin Chen et Yong Liang. « Preparation of Synthetic Amanitin Epitope Imprinted Polymers via Thiol-ene Click Reaction for Recognition and Extraction α- and β-Amanitins from Mushrooms ». Chromatographia 82, n^o 9 (22 juin 2019) : 1355–63. http://dx.doi.org/10.1007/s10337-019-03751-8.

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Gao, Jiale, Nuoya Liu, Xiaomeng Zhang, En Yang, Yuzhu Song, Jinyang Zhang et Qinqin Han. « Utilizing the DNA Aptamer to Determine Lethal α-Amanitin in Mushroom Samples and Urine by Magnetic Bead-ELISA (MELISA) ». Molecules 27, n^o 2 (15 janvier 2022) : 538. http://dx.doi.org/10.3390/molecules27020538.

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Amanita poisoning is one of the most deadly types of mushroom poisoning. α-Amanitin is the main lethal toxin in amanita, and the human-lethal dose is about 0.1 mg/kg. Most of the commonly used detection techniques for α-amanitin require expensive instruments. In this study, the α-amanitin aptamer was selected as the research object, and the stem-loop structure of the original aptamer was not damaged by truncating the redundant bases, in order to improve the affinity and specificity of the aptamer. The specificity and affinity of the truncated aptamers were determined using isothermal titration calorimetry (ITC) and gold nanoparticles (AuNPs), and the affinity and specificity of the aptamers decreased after truncation. Therefore, the original aptamer was selected to establish a simple and specific magnetic bead-based enzyme linked immunoassay (MELISA) method for α-amanitin. The detection limit was 0.369 μg/mL, while, in mushroom it was 0.372 μg/mL and in urine 0.337 μg/mL. Recovery studies were performed by spiking urine and mushroom samples with α-amanitin, and these confirmed the desirable accuracy and practical applicability of our method. The α-amanitin and aptamer recognition sites and binding pockets were investigated in an in vitro molecular docking environment, and the main binding bases of both were T3, G4, C5, T6, T7, C67, and A68. This study truncated the α-amanitin aptamer and proposes a method of detecting α-amanitin.

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Vaisius, A. C., et H. Faulstich. « A soluble biotinyl-α-amanitin affinity probe for the isolation of RNA polymerase B ». Biochemistry and Cell Biology 64, n^o 9 (1 septembre 1986) : 923–29. http://dx.doi.org/10.1139/o86-123.

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Utilizing the 6′-hydroxyindole moiety of α-amanitin for substitution, biotinyl-α-amanitin has been synthesized to use as a soluble affinity probe for the isolation of RNA polymerase B from mammalian cell culture. The synthetic biotinyl-α-amanitin remains a potent inhibitor of RNA polymerase B having a Ki of 4.1 × 10−8 M as compared with a Ki of 5 × 10−9 M for natural α-amanitin. RNA polymerase B complexed with biotinyl-α-amanitin can be isolated on Bio-Gel P300 polyacrylamide gel beads to which avidin has been attached. RNA polymerase B may then be released from the complex by treatment with sodium dodecyl sulfate or by monochromatic irradiation at 314 nm which destroys the amatoxin moiety. We have used this affinity probe to analyze the subunit composition of RNA polymerase B from various mouse myeloma cell lines. We believe that the biotinyl-α-amanitin may be very useful for the isolation of factors which associate with RNA polymerase B; e.g., we have substantiated that actin can be associated with RNA polymerase.

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Bang, Young Yoon, Im-Sook Song, Min Seo Lee, Chang Ho Lim, Yong-Yeon Cho, Joo Young Lee, Han Chang Kang et Hye Suk Lee. « Toxicokinetics of β-Amanitin in Mice and In Vitro Drug–Drug Interaction Potential ». Pharmaceutics 14, n^o 4 (1 avril 2022) : 774. http://dx.doi.org/10.3390/pharmaceutics14040774.

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The toxicokinetics of β-amanitin, a toxic bicyclic octapeptide present abundantly in Amanitaceae mushrooms, was evaluated in mice after intravenous (iv) and oral administration. The area under plasma concentration curves (AUC) following iv injection increased in proportion to doses of 0.2, 0.4, and 0.8 mg/kg. β-amanitin disappeared rapidly from plasma with a half-life of 18.3–33.6 min, and 52.3% of the iv dose was recovered as a parent form. After oral administration, the AUC again increased in proportion with doses of 2, 5, and 10 mg/kg. Absolute bioavailability was 7.3–9.4%, which resulted in 72.4% of fecal recovery from orally administered β-amanitin. Tissue-to-plasma AUC ratios of orally administered β-amanitin were the highest in the intestine and stomach. It also readily distributed to kidney > spleen > lung > liver ≈ heart. Distribution to intestines, kidneys, and the liver is in agreement with previously reported target organs after acute amatoxin poisoning. In addition, β-amanitin weakly or negligibly inhibited major cytochrome P450 and 5′-diphospho-glucuronosyltransferase activities in human liver microsomes and suppressed drug transport functions in mammalian cells that overexpress transporters, suggesting the remote drug interaction potentials caused by β-amanitin exposure.

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Pryyma, Alla, Kaveh Matinkhoo, Antonio A. W. L. Wong et David M. Perrin. « Meeting key synthetic challenges in amanitin synthesis with a new cytotoxic analog : 5′-hydroxy-6′-deoxy-amanitin ». Chemical Science 11, n^o 43 (2020) : 11927–35. http://dx.doi.org/10.1039/d0sc04150e.

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Bodero, Lizeth, Paula López Rivas, Barbara Korsak, Torsten Hechler, Andreas Pahl, Christoph Müller, Daniela Arosio, Luca Pignataro, Cesare Gennari et Umberto Piarulli. « Synthesis and biological evaluation of RGD and isoDGR peptidomimetic-α-amanitin conjugates for tumor-targeting ». Beilstein Journal of Organic Chemistry 14 (14 février 2018) : 407–15. http://dx.doi.org/10.3762/bjoc.14.29.

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RGD-α-amanitin and isoDGR-α-amanitin conjugates were synthesized by joining integrin ligands to α-amanitin via various linkers and spacers. The conjugates were evaluated for their ability to inhibit biotinylated vitronectin binding to the purified αVβ3 receptor, retaining good binding affinity, in the same nanomolar range as the free ligands. The antiproliferative activity of the conjugates was evaluated in three cell lines possessing different levels of αVβ3 integrin expression: human glioblastoma U87 (αVβ3+), human lung carcinoma A549 (αVβ3−) and breast adenocarcinoma MDA-MB-468 (αVβ3−). In the U87, in the MDA-MB-468, and partly in the A549 cancer cell lines, the cyclo[DKP-isoDGR]-α-amanitin conjugates bearing the lysosomally cleavable Val-Ala linker were found to be slightly more potent than α-amanitin. Apparently, for all these α-amanitin conjugates there is no correlation between the cytotoxicity and the expression of αVβ3 integrin. To determine whether the increased cytotoxicity of the cyclo[DKP-isoDGR]-α-amanitin conjugates is governed by an integrin-mediated binding and internalization process, competition experiments were carried out in which the conjugates were tested with U87 (αVβ3+, αVβ5+, αVβ6−, α5β1+) and MDA-MB-468 (αVβ3−, αVβ5+, αVβ6+, α5β1−) cells in the presence of excess cilengitide, with the aim of blocking integrins on the cell surface. Using the MDA-MB-468 cell line, a fivefold increase of the IC50 was observed for the conjugates in the presence of excess cilengitide, which is known to strongly bind not only αVβ3, but also αVβ5, αVβ6, and α5β1. These data indicate that in this case the cyclo[DKP-isoDGR]-α-amanitin conjugates are possibly internalized by a process mediated by integrins different from αVβ3 (e.g., αVβ5).

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Rogalski, T. M., A. M. Bullerjahn et D. L. Riddle. « Lethal and amanitin-resistance mutations in the Caenorhabditis elegans ama-1 and ama-2 genes. » Genetics 120, n^o 2 (1 octobre 1988) : 409–22. http://dx.doi.org/10.1093/genetics/120.2.409.

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Abstract Mutants of Caenorhabditis elegans resistant to alpha-amanitin have been isolated at a frequency of about 1.6 x 10(-6) after EMS mutagenesis of the wild-type strain, N2. Four new dominant resistance mutations have been studied genetically. Three are alleles of a previously identified gene, ama-1 IV, encoding the largest subunit of RNA polymerase II. The fourth mutation defines a new gene, ama-2 V. Unlike the ama-1 alleles, the ama-2 mutation exhibits a recessive-lethal phenotype. Growth and reproduction of N2 was inhibited at a concentration of 10 micrograms/ml amanitin, whereas ama-2/+ animals were inhibited at 100 micrograms/ml, and 800 micrograms/ml was required to inhibit growth of ama-1/+ larvae. We have also determined that two reference strains used for genetic mapping, dpy-11(e224)V and sma-1(e30)V, are at least four-fold more sensitive to amanitin that the wild-type strain. Using an amanitin-resistant ama-1(m118) or ama-1(m322) strain as a parent, we have isolated amanitin-sensitive mutants that carry recessive-lethal ama-1 alleles. The frequency of EMS-induced lethal ama-1 mutations is approximately 1.7 x 10(-3), 1000-fold higher than the frequency of amanitin-resistance alleles. Nine of the lethal alleles are apparent null mutations, and they exhibit L1-lethal phenotypes at both 20 degrees and 25 degrees. Six alleles result in partial loss of RNA polymerase II function as determined by their sterile phenotypes at 20 degrees. All but one of these latter mutations exhibit a more severe phenotype at 25 degrees C. We have also selected seven EMS-induced revertants of three different ama-1 lethals. These revertants restore dominant resistance to amanitin. The selection for revertants also produced eight new dominant amanitin resistance alleles on the balancer chromosome, nT1.

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Yee, Mok Mai, Leslie W. Woods, Robert H. Poppenga et Birgit Puschner. « Amanitin intoxication in two beef calves in California ». Journal of Veterinary Diagnostic Investigation 24, n^o 1 (6 décembre 2011) : 241–44. http://dx.doi.org/10.1177/1040638711427947.

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Two 2- and 3-month-old beef calves from 2 separate herds, locations, and times were found dead and were submitted to the veterinary diagnostic laboratory for diagnostic work-up. In both cases, no premonitory signs were seen by the owners. Histopathology revealed acute panlobular hepatic necrosis in both calves. In addition, calf A had copper and selenium deficiency, and calf B had oxalate nephrosis, and selenium and zinc deficiencies. Alpha-amanitin was detected in the urine from calf A, and in the liver and rumen contents from calf B using liquid chromatography–mass spectrometry. The cause of panlobular hepatic necrosis and death of both calves was determined to be amanitin toxicosis from ingestion of amanitin-containing mushrooms based on microscopic changes and toxicological analysis of tissues. In cases of sudden death in cows with histopathological findings of panlobular hepatic necrosis, toxicological analysis for amanitin is needed for a definitive diagnosis of poisoning by amanitin-containing mushrooms.

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Luo, Hong, Heather E. Hallen-Adams, John S. Scott-Craig et Jonathan D. Walton. « Colocalization of Amanitin and a Candidate Toxin-Processing Prolyl Oligopeptidase in Amanita Basidiocarps ». Eukaryotic Cell 9, n^o 12 (1 octobre 2010) : 1891–900. http://dx.doi.org/10.1128/ec.00161-10.

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ABSTRACT Fungi in the basidiomycetous genus Amanita owe their high mammalian toxicity to the bicyclic octapeptide amatoxins such as α-amanitin. Amatoxins and the related phallotoxins (such as the heptapeptide phalloidin) are encoded by members of the “MSDIN” gene family and are synthesized on ribosomes as short (34- to 35-amino-acid) proproteins. Antiamanitin antibodies and confocal microscopy were used to determine the cellular and subcellular localizations of amanitin accumulation in basidiocarps (mushrooms) of the Eastern North American destroying angel (Amanita bisporigera). Consistent with previous studies, amanitin is present throughout the basidiocarp (stipe, pileus, lamellae, trama, and universal veil), but it is present in only a subset of cells within these tissues. Restriction of amanitin to certain cells is especially marked in the hymenium. Several lines of evidence implicate a specific prolyl oligopeptidase, A. bisporigera POPB (AbPOPB), in the initial processing of the amanitin and phallotoxin proproteins. The gene for AbPOPB is restricted taxonomically to the amatoxin-producing species of Amanita and is clustered in the genome with at least one expressed member of the MSDIN gene family. Immunologically, amanitin and AbPOPB show a high degree of colocalization, indicating that toxin biosynthesis and accumulation occur in the same cells and possibly in the same subcellular compartments.

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Bartolomei, M. S., et J. L. Corden. « Localization of an alpha-amanitin resistance mutation in the gene encoding the largest subunit of mouse RNA polymerase II ». Molecular and Cellular Biology 7, n^o 2 (février 1987) : 586–94. http://dx.doi.org/10.1128/mcb.7.2.586-594.1987.

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RNA polymerase II is inhibited by the mushroom toxin alpha-amanitin. A mouse BALB/c 3T3 cell line was selected for resistance to alpha-amanitin and characterized in detail. This cell line, designated A21, was heterozygous, possessing both amanitin-sensitive and -resistant forms of RNA polymerase II; the mutant form was 500 times more resistant to alpha-amanitin than the sensitive form. By using the wild-type mouse RNA polymerase II largest subunit (RPII215) gene (J.A. Ahearn, M.S. Bartolomei, M. L. West, and J. L. Corden, submitted for publication) as the probe, RPII215 genes were isolated from an A21 genomic DNA library. The mutant allele was identified by its ability to transfer amanitin resistance in a transfection assay. Genomic reconstructions between mutant and wild-type alleles localized the mutation to a 450-base-pair fragment that included parts of exons 14 and 15. This fragment was sequenced and compared with the wild-type sequence; a single AT-to-GC transition was detected at nucleotide 6819, corresponding to an asparagine-to-aspartate substitution at amino acid 793 of the predicted protein sequence. Knowledge of the position of the A21 mutation should facilitate the study of the mechanism of alpha-amanitin resistance. Furthermore, the A21 gene will be useful for studying the phenotype of site-directed mutations in the RPII215 gene.

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Bartolomei, M. S., et J. L. Corden. « Localization of an alpha-amanitin resistance mutation in the gene encoding the largest subunit of mouse RNA polymerase II. » Molecular and Cellular Biology 7, n^o 2 (février 1987) : 586–94. http://dx.doi.org/10.1128/mcb.7.2.586.

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RNA polymerase II is inhibited by the mushroom toxin alpha-amanitin. A mouse BALB/c 3T3 cell line was selected for resistance to alpha-amanitin and characterized in detail. This cell line, designated A21, was heterozygous, possessing both amanitin-sensitive and -resistant forms of RNA polymerase II; the mutant form was 500 times more resistant to alpha-amanitin than the sensitive form. By using the wild-type mouse RNA polymerase II largest subunit (RPII215) gene (J.A. Ahearn, M.S. Bartolomei, M. L. West, and J. L. Corden, submitted for publication) as the probe, RPII215 genes were isolated from an A21 genomic DNA library. The mutant allele was identified by its ability to transfer amanitin resistance in a transfection assay. Genomic reconstructions between mutant and wild-type alleles localized the mutation to a 450-base-pair fragment that included parts of exons 14 and 15. This fragment was sequenced and compared with the wild-type sequence; a single AT-to-GC transition was detected at nucleotide 6819, corresponding to an asparagine-to-aspartate substitution at amino acid 793 of the predicted protein sequence. Knowledge of the position of the A21 mutation should facilitate the study of the mechanism of alpha-amanitin resistance. Furthermore, the A21 gene will be useful for studying the phenotype of site-directed mutations in the RPII215 gene.

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Ventura, Salvador, Cristina Ruiz, Elena Durán, Marta Mosquera, Fernando Bandrés, Francesc Campos, Bartomeu Castanyer et al. « Amanitinas ». Revista del Laboratorio Clínico 8, n^o 3 (juillet 2015) : 109–26. http://dx.doi.org/10.1016/j.labcli.2015.05.001.

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Lüli, Yunjiao, Shengwen Zhou, Xuan Li, Zuohong Chen, Zhuliang Yang et Hong Luo. « Differential Expression of Amanitin Biosynthetic Genes and Novel Cyclic Peptides in Amanita molliuscula ». Journal of Fungi 7, n^o 5 (14 mai 2021) : 384. http://dx.doi.org/10.3390/jof7050384.

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Amanita molliuscula is a basal species of lethal Amanita and intrigues the field because it does not produce discernable α-amanitin when inspected by High Performance Liquid Chromatography (HPLC), which sets it apart from all known amanitin-producing (lethal) Amanita species. In order to study the underlining genetic basis of the phenotype, we sequenced this species through PacBio and Illumina RNA-Seq platforms. In total, 17 genes of the “MSDIN” family (named after the first five amino acid residues of the precursor peptides) were found in the genome and 11 of them were expressed at the transcription level. The expression pattern was not even but in a differential fashion: two of the MSDINs were highly expressed (FPKM value > 100), while the majority were expressed at low levels (FPKM value < 1). Prolyl oligopeptidease B (POPB) is the key enzyme in the amanitin biosynthetic pathway, and high expression of this enzyme was also discovered (FPKM value > 100). The two MSDINs with highest transcription further translated into two novel cyclic peptides, the structure of which is distinctive from all known cyclic peptides. The result illustrates the correlation between the expression and the final peptide products. In contrast to previous HPLC result, the genome of A. molliuscula harbors α-amanitin genes (three copies), but the product was in trace amount indicated by MS. Overall, transcription of MSDINs encoding major toxins (α-amanitin, β-amanitin, phallacidin and phalloidin) were low, showing that these toxins were not actively synthesized at the stage. Collectively, our results indicate that the amanitin biosynthetic pathway is highly active at the mature fruiting body stage in A. molliuscula, and due to the differential expression of MSDIN genes, the pathway produces only a few cyclic peptides at the time.

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Mydlík, M., K. Derzsiová, J. Klán et T. Zíma. « Hemoperfusion with α-Amanitin : An in Vitro Study ». International Journal of Artificial Organs 20, n^o 2 (février 1997) : 105–7. http://dx.doi.org/10.1177/039139889702000210.

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The authors carried out sixteen hemoperfusions with α-amanitin in vitro in a closed system using active charcoal, Amberlite XAD-2 and Amberlite XAD-4 in hemoperfusion capsules. As a perfusion solution 4 liters of 0.9% NaCl solution was used. The α-amanitin concentration in the solution was 8.3 ± 0.36 mg/L. Individual hemoperfusion lasted 5 hours. Two hundred and forty minutes of Amberlite XAD-2 hemoperfusion led to the zero values of α-amanitin concentration in 0.9% NaCI solution. When using active charcoal the adsorption capacity of the hemoperfusion capsule was already exhausted at 120 min. The results gathered suggest that the most effective α-amanitin hemoperfusion in vitro was obtained with Amberlite XAD-2 and the least effective with active charcoal. The authors recommend the use of hemoperfusion with Amberlite XAD-2 for acute intoxication with Amanita phalloides in humans up to 24-36 hours after poisoning.

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Edgar, L. G., N. Wolf et W. B. Wood. « Early transcription in Caenorhabditis elegans embryos ». Development 120, n^o 2 (1 février 1994) : 443–51. http://dx.doi.org/10.1242/dev.120.2.443.

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We have analysed early transcription in devitellinized, cultured embryos of the nematode Caenorhabditis elegans by two methods: measurement of [32P]UTP uptake into TCA-precipitable material and autoradiographic detection of [3H]UTP labelling both in the presence and absence of alpha-amanitin. RNA synthesis was first detected at the 8- to 12-cell stage, and alpha-amanitin sensitivity also appeared at this time, during the cleavages establishing the major founder cell lineages. The requirements for maternally supplied versus embryonically produced gene products in early embryogenesis were examined in the same culture system by observing the effects of alpha-amanitin on cell division and the early stereotyped lineage patterns. In the presence of high levels of alpha-amanitin added at varying times from two cells onward, cell division continued until approximately the 100-cell stage and then stopped during a single round of cell division. The characteristic unequal early cleavages, orientation of cleavage planes and lineage-specific timing of early divisions were unaffected by alpha-amanitin in embryos up to 87 cells. These results indicate that embryonic transcription starts well before gastrulation in C. elegans embryos, but that although embryonic transcripts may have important early functions, maternal products can support at least the mechanics of the first 6 to 7 cell cycles.

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Wienland, T., et H. Faulstich. « Fifty years of amanitin ». Experientia 47, n^o 11-12 (décembre 1991) : 1186–93. http://dx.doi.org/10.1007/bf01918382.

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Chung, H. M., M. G. Lee, P. Dietrich, J. Huang et L. H. Van der Ploeg. « Disruption of largest subunit RNA polymerase II genes in Trypanosoma brucei ». Molecular and Cellular Biology 13, n^o 6 (juin 1993) : 3734–43. http://dx.doi.org/10.1128/mcb.13.6.3734-3743.1993.

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Two types of largest subunit RNA polymerase II (pol II) genes (pol IIA and pol IIB), differing in 3 amino acid substitutions, are encoded in the Trypanosoma brucei (stock 427-60) genome. As a result, the alpha-amanitin-resistant transcription of the procyclic acidic repetitive protein (PARP) and variant surface glycoprotein (VSG) genes was proposed to involve a modified, alpha-amanitin-resistant form of the largest subunit of pol II. Alternatively, pol I could transcribe the PARP and VSG genes. To discriminate between these two models, we deleted the N-terminal domain (about one-third of the polypeptide), which encodes the amino acid substitutions which discriminated the pol IIA and pol IIB genes, at both pol IIB alleles. The pol IIB- trypanosomes still transcribe the PARP genes and the VSG gene promoter region in insect-form trypanosomes by alpha-amanitin-resistant RNA polymerases, while control housekeeping genes are transcribed in an alpha-amanitin-sensitive manner, presumably by pol IIA. We conclude that the alpha-amanitin-resistant transcription of protein coding genes in T. brucei is not mediated by a diverged form of the largest subunit of pol II and that the presence of both the pol IIA and pol IIB genes is not essential for trypanosome viability. This conclusion was further supported by the finding that individual trypanosome variants exhibited allelic heterogeneity for the previously identified amino acid substitutions and that various permutations of the polymorphic amino acids generate at least four different types of largest subunit pol II genes. The expression of the PARP genes and the VSG gene promoter region by alpha-amanitin-resistant RNA polymerases in the pol IIB- trypanosomes provides evidence for transcription of these genes by pol I.

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Chung, H. M., M. G. Lee, P. Dietrich, J. Huang et L. H. Van der Ploeg. « Disruption of largest subunit RNA polymerase II genes in Trypanosoma brucei. » Molecular and Cellular Biology 13, n^o 6 (juin 1993) : 3734–43. http://dx.doi.org/10.1128/mcb.13.6.3734.

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Two types of largest subunit RNA polymerase II (pol II) genes (pol IIA and pol IIB), differing in 3 amino acid substitutions, are encoded in the Trypanosoma brucei (stock 427-60) genome. As a result, the alpha-amanitin-resistant transcription of the procyclic acidic repetitive protein (PARP) and variant surface glycoprotein (VSG) genes was proposed to involve a modified, alpha-amanitin-resistant form of the largest subunit of pol II. Alternatively, pol I could transcribe the PARP and VSG genes. To discriminate between these two models, we deleted the N-terminal domain (about one-third of the polypeptide), which encodes the amino acid substitutions which discriminated the pol IIA and pol IIB genes, at both pol IIB alleles. The pol IIB- trypanosomes still transcribe the PARP genes and the VSG gene promoter region in insect-form trypanosomes by alpha-amanitin-resistant RNA polymerases, while control housekeeping genes are transcribed in an alpha-amanitin-sensitive manner, presumably by pol IIA. We conclude that the alpha-amanitin-resistant transcription of protein coding genes in T. brucei is not mediated by a diverged form of the largest subunit of pol II and that the presence of both the pol IIA and pol IIB genes is not essential for trypanosome viability. This conclusion was further supported by the finding that individual trypanosome variants exhibited allelic heterogeneity for the previously identified amino acid substitutions and that various permutations of the polymorphic amino acids generate at least four different types of largest subunit pol II genes. The expression of the PARP genes and the VSG gene promoter region by alpha-amanitin-resistant RNA polymerases in the pol IIB- trypanosomes provides evidence for transcription of these genes by pol I.

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Rogalski, T. M., M. Golomb et D. L. Riddle. « Mutant Caenorhabditis elegans RNA polymerase II with a 20,000-fold reduced sensitivity to alpha-amanitin. » Genetics 126, n^o 4 (1 décembre 1990) : 889–98. http://dx.doi.org/10.1093/genetics/126.4.889.

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Abstract A doubly mutant ama-1(m118m526) gene results in an RNA polymerase (Rpo) II that is unusually resistant to alpha-amanitin. Rpo II activity in isolated Caenorhabditis elegans cell nuclei is inhibited 50% by alpha-amanitin at a concentration of 150 micrograms/ml, making this enzyme 150 times more resistant to the toxin than Rpo II from the singly mutant allele, ama-1(m118), 20,000 times more resistant than the wild-type Rpo II, and about six times more resistant to amanitin than is Rpo III. It was determined that the SL1 spliced leader precursor is transcribed by Rpo II, and this transcript was used to measure Rpo II activity. The Rpo II activity is unstable in vitro, and the mutant strain has a temperature-sensitive sterile phenotype. The highly resistant double mutant was selected among four million progeny of the mutagenized ama-1(m118) parent by its ability to grow and reproduce in 200 micrograms/ml amanitin in the presence of a permeabilizing agent, Triton X-100.

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Barbosa, Isabel, Cátia Domingues, Rui M. Barbosa et Fernando Ramos. « Amanitins in Wild Mushrooms : The Development of HPLC-UV-EC and HPLC-DAD-MS Methods for Food Safety Purposes ». Foods 11, n^o 23 (5 décembre 2022) : 3929. http://dx.doi.org/10.3390/foods11233929.

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Mushroom poisoning remains a serious food safety and health concern in some parts of the world due to its morbidity and mortality. Identification of mushroom toxins at an early stage of suspected intoxication is crucial for a rapid therapeutic decision. In this study, a new extraction method was developed to determine α- and β-amanitin in mushroom samples collected from central Portugal. High-performance liquid chromatography with in-line ultraviolet and electrochemical detection was implemented to improve the specificity of the method. The method was fully validated for linearity (0.5–20.0 µg·mL−1), sensitivity, recovery, and precision based on a matrix-matched calibration method. The limit of detection was 55 µg mL−1 (UV) and 62 µg mL−1 (EC) for α-amanitin and 64 µg mL−1 (UV) and 24 µg mL−1 (EC) for β–amanitin. Intra- and inter-day precision differences were less than 13%, and the recovery ratios ranged from 89% to 117%. The developed method was successfully applied to fourteen Amanita species (A. sp.) and compared with five edible mushroom samples after extraction with Oasis® PRIME HLB cartridges without the conditioning and equilibration step. The results revealed that the A. phalloides mushrooms present the highest content of α- and β-amanitin, which is in line with the HPLC-DAD-MS. In sum, the developed analytical method could benefit food safety assessment and contribute to food-health security, as it is rapid, simple, sensitive, accurate, and selectively detects α- and β-amanitin in any mushroom samples.

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de Mercoyrol, L., C. Job et D. Job. « Studies on the inhibition by α-amanitin of single-step addition reactions and productive RNA synthesis catalysed by wheat-germ RNA polymerase II ». Biochemical Journal 258, n^o 1 (15 février 1989) : 165–69. http://dx.doi.org/10.1042/bj2580165.

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The rate of formation of a single phosphodiester bond with UTP substrate, U-A primer, poly[d(A-T)] template and wheat-germ RNA polymerase II is greatly depressed in the presence of alpha-amanitin. Half-maximal inhibition occurs at 0.04 microgram/ml, in close agreement with published values for inhibition of productive RNA synthesis with class II RNA polymerases from higher-plant species. However, a sizeable proportion of U-A-U synthesis is resistant to inhibition by excess alpha-amanitin. In the additional presence of ATP, i.e. under experimental conditions permitting RNA chain elongation, the synthesis of poly[r(A-U)] is arrested after the formation of the first phosphodiester bond. The results support the contention that the main enzymic process disrupted by alpha-amanitin is the translocation step of the transcription complex along the DNA template.

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Bullerjahn, A. M., et D. L. Riddle. « Fine-structure genetics of ama-1, an essential gene encoding the amanitin-binding subunit of RNA polymerase II in Caenorhabditis elegans. » Genetics 120, n^o 2 (1 octobre 1988) : 423–34. http://dx.doi.org/10.1093/genetics/120.2.423.

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Abstract A fine-structure genetic map has been constructed for ama-1 IV, an essential gene in Caenorhabditis elegans encoding the amanitin-binding subunit of RNA polymerase II. Sixteen EMS-induced recessive-lethal mutations have been positioned in the gene by determining their intragenic recombination frequencies with m118, a mutation that confers dominant resistance to alpha-amanitin. The 16 mutants, all isolated in the ama-1(m118) background, include 13 that are early larval lethals, and three that are mid-larval lethals, at 25 degrees. Six of the mutants exhibit temperature-dependence in the severity of their phenotype. Intragenic recombination between the lethal site and the parental resistance mutation was detected by means of resistance to amanitin. Recombinants were detected at frequencies as low as 2 X 10(-6). The segregation of the closely linked flanking markers, unc-17 and unc-5, revealed whether the lethal mutation was to the left or the right of m118. By adding the distances between the extreme left and right mutations, the ama-1 gene is estimated to be 0.011 map unit long, with m118 positioned 0.004 map unit from the left-most lethal mutation. To order the lethal mutations with respect to each other, viable heteroallelic strains were constructed using the free duplication, mDp1[unc-17(e113) dpy-13(+) ama-1(+)]. The heteroallelic strains were sensitive to amanitin, and recombination events between the lethal mutations were specifically selected by means of the dominant amanitin resistance encoded on the recombinant chromosome. The segregation of outside markers revealed the left-right order of the lethal mutations. The position of mutations within the gene is nonrandom. Functional domains of the ama-1 gene indicated by the various lethal phenotypes are discussed.

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Bever, Candace S., Robert M. Hnasko, Luisa W. Cheng et Larry H. Stanker. « A Rapid Extraction Method Combined with a Monoclonal Antibody-Based Immunoassay for the Detection of Amatoxins ». Toxins 11, n^o 12 (11 décembre 2019) : 724. http://dx.doi.org/10.3390/toxins11120724.

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Amatoxins (AMAs) are lethal toxins found in a variety of mushroom species. Detection methods are needed to determine the occurrence of AMAs in mushroom species suspected in mushroom poisonings. In this manuscript, we report the generation of novel monoclonal antibodies (mAbs, AMA9G3 and AMA9C12) and the development of a competitive, enzyme-linked immunosorbent assay (cELISA) that is sensitive at 1 ng mL−1 and shows selectivity for α-amanitin (α-AMA) and γ-amanitin (γ-AMA), and less for β-amanitin (β-AMA). In order to decrease the overall time needed for analysis, the extraction procedure for mushrooms was also simplified. A rapid (1 min) extraction procedure of AMAs using solvents as simple as water alone was successfully demonstrated using Amanita mushrooms. Together, the extraction method and the mAb-based ELISA represent a simple and rapid method that readily detects AMAs extracted from mushroom samples.

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Moshnikova, Anna, Valentina Moshnikova, Oleg A. Andreev et Yana K. Reshetnyak. « Antiproliferative Effect of pHLIP-Amanitin ». Biochemistry 52, n^o 7 (8 février 2013) : 1171–78. http://dx.doi.org/10.1021/bi301647y.

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Bartolomei, M. S., N. F. Halden, C. R. Cullen et J. L. Corden. « Genetic analysis of the repetitive carboxyl-terminal domain of the largest subunit of mouse RNA polymerase II ». Molecular and Cellular Biology 8, n^o 1 (janvier 1988) : 330–39. http://dx.doi.org/10.1128/mcb.8.1.330-339.1988.

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The carboxyl-terminal domain (CTD) of the mouse RNA polymerase II largest subunit consists of 52 repeats of a seven-amino-acid block with the consensus sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser. A genetic approach was used to determine whether the CTD plays an essential role in RNA polymerase function. Deletion, insertion, and substitution mutations were created in the repetitive region of an alpha-amanitin-resistant largest-subunit gene. The effects of these mutations on RNA polymerase II activity were assayed by measuring the ability of mutant genes to confer alpha-amanitin resistance after transfection of susceptible rodent cells. Mutations that resulted in CTDs containing between 36 and 78 repeats had no effect on the transfer of alpha-amanitin resistance, whereas mutations with 25 or fewer repeats were inactive in this assay. Mutations that contained 29, 31, or 32 repeats had an intermediate effect; the number of alpha-amanitin-resistant colonies was lower and the colonies obtained were smaller, indicating that the mutant RNA polymerase II was defective. In addition, not all of the heptameric repeats were functionally equivalent in that repeats that diverged in up to three amino acids from the consensus sequence could not substitute for the conserved heptamer repeats. We concluded that the CTD is essential for RNA polymerase II activity, since substantial mutations in this region result in loss of function.

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Bartolomei, M. S., N. F. Halden, C. R. Cullen et J. L. Corden. « Genetic analysis of the repetitive carboxyl-terminal domain of the largest subunit of mouse RNA polymerase II. » Molecular and Cellular Biology 8, n^o 1 (janvier 1988) : 330–39. http://dx.doi.org/10.1128/mcb.8.1.330.

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The carboxyl-terminal domain (CTD) of the mouse RNA polymerase II largest subunit consists of 52 repeats of a seven-amino-acid block with the consensus sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser. A genetic approach was used to determine whether the CTD plays an essential role in RNA polymerase function. Deletion, insertion, and substitution mutations were created in the repetitive region of an alpha-amanitin-resistant largest-subunit gene. The effects of these mutations on RNA polymerase II activity were assayed by measuring the ability of mutant genes to confer alpha-amanitin resistance after transfection of susceptible rodent cells. Mutations that resulted in CTDs containing between 36 and 78 repeats had no effect on the transfer of alpha-amanitin resistance, whereas mutations with 25 or fewer repeats were inactive in this assay. Mutations that contained 29, 31, or 32 repeats had an intermediate effect; the number of alpha-amanitin-resistant colonies was lower and the colonies obtained were smaller, indicating that the mutant RNA polymerase II was defective. In addition, not all of the heptameric repeats were functionally equivalent in that repeats that diverged in up to three amino acids from the consensus sequence could not substitute for the conserved heptamer repeats. We concluded that the CTD is essential for RNA polymerase II activity, since substantial mutations in this region result in loss of function.

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Gonmori, Kunio, Kayoko Minakata, Masako Suzuki, Itaru Yamagishi, Hideki Nozawa, Koutaro Hasegawa, Amin Wurita, Kanako Watanabe et Osamu Suzuki. « MALDI-TOF mass spectrometric analysis of α-amanitin, β-amanitin, and phalloidin in urine ». Forensic Toxicology 30, n^o 2 (20 juin 2012) : 179–84. http://dx.doi.org/10.1007/s11419-012-0145-6.

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Kananen-Anttila, K., M. Eronen, J. Matilainen, M. Kallio, J. Peippo et M. Halmekytö. « 329 SUPPRESSION OF BOVINE OOCYTE IVM BY SERUM AND FSH DEPRIVATION OR BY α-AMANITIN : EFFECT ON FERTILIZATION AND EMBRYO DEVELOPMENT ». Reproduction, Fertility and Development 18, n^o 2 (2006) : 272. http://dx.doi.org/10.1071/rdv18n2ab329.

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We have studied the effect of suppressed IVM on the developmental competence of bovine oocytes, aiming at elucidating the importance of cytoplasmic maturation in fertilization and embryo development. Six replicates of abattoir-derived oocytes were randomly divided into three IVM groups. Control (n = 950): TCM-199 with glutamax-I (Gibco, Grand Island, NY, USA), 0.25 mM Na-pyruvate, 100 IU mL−1 penicillin and 100 μg mL−1 streptomycin, 50 ng mL−1 FSH, and 10% fetal bovine serum (FBS) (Gibco); Serum+FSH-free (n = 944): same as control but without FSH and FBS; α-amanitin (n = 977): same as control but with 10 μg mL−1 α-amanitin. Nuclear maturation of oocytes was studied 24 h after the onset of IVM, the formation of sperm aster structure 10 hours post-insemination (hpi) and the formation of pronuclei 20 hpi. Sperm aster was visualized with β-tubulin antibody (modified from Navara et al. 1999 Dev. Biol. 162, 29–40). Presumptive zygotes were cultured until Day 7 in modified SOFaaci + 4 mg mL−1 fatty acid-free BSA in 5% O2. Cumulus cell expansion was seen only in the control group. The results of nuclear maturation, fertilization, and embryo development are summarized in Table 1. Serum and FSH deprivation did not have a statistically significant effect on the parameters studied (vs. control). α-amanitin exposure during IVM reduced nuclear maturation, fertilization, and Day 3 embryo cleavage vs. control, and resulted in total blockage of Day 7 blastocyst development. The treatment groups had significantly smaller mean diameters of male pronuclei (control: 14 ± 0.6 μÂm; serum+FSH-free: 12 ± 0.5 μÂm, P < 0.05; α-amanitin: 10 ± 0.6 μÂm, P < 0.001) and sperm asters (control: 86 ± 4 μÂm; serum+FSH-free: 82 ± 4 μÂm, P < 0.01; α-amanitin: 49 ± 7 μm, P < 0.001) (nonparametric Kruskall Wallis and Mann-Whitney U tests) vs. control group. Despite reduction in pronucleus and sperm aster diameter, serum and FSH deprivation during IVM did not affect in vitro developmental competence of bovine oocytes, suggesting a need for re-evaluation of the components of IVM. α-Amanitin exposure in IVM disturbed nuclear maturation, fertilization, and embryo development, indicating the essence of early transcription. Table 1. Average percentages ± (n) for nuclear maturation, fertilization (min two pronuclei), embryo cleavage, and blastocyst development

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Han, Qinqin, Xueshan Xia, Le Jing, Pu Qiao, Jie Li, Mingwei Qin, Xiaomeng Zhang, Yuzhu Song, Jinyang Zhang et Qiang Chen. « Selection and characterization of DNA aptamer specially targeting α-amanitin in wild mushrooms ». SDRP Journal of Food Science & ; Technology 3, n^o 6 (2018) : 497–508. http://dx.doi.org/10.25177/jfst.3.6.2.

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Li, Yi-Jia, Thomas Macnaughton, Lu Gao et Michael M. C. Lai. « RNA-Templated Replication of Hepatitis Delta Virus : Genomic and Antigenomic RNAs Associate with Different Nuclear Bodies ». Journal of Virology 80, n^o 13 (1 juillet 2006) : 6478–86. http://dx.doi.org/10.1128/jvi.02650-05.

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ABSTRACT Lacking an RNA-dependent RNA polymerase, hepatitis delta virus (HDV), which contains a circular RNA of 1.7 kilobases, is nonetheless able to replicate its RNA by use of cellular transcription machineries. Previously, we have shown that the replications of genomic- and antigenomic-strand HDV RNAs have different sensitivities to α-amanitin, suggesting that these two strands are synthesized in different transcription machineries in the cells, but the nature of these transcription machineries is not clear. In this study, we performed metabolic labeling and immunofluorescence staining of newly synthesized HDV RNA with bromouridine after HDV RNA transfection into hepatocytes and confirmed that HDV RNA synthesis had both α-amanitin-sensitive and -resistant components. The antigenomic RNA labeling was α-amanitin resistant and localized to the nucleolus. The genomic RNA labeling was α-amanitin sensitive and more diffusely localized in the nucleoplasm. Most of the genomic RNA labeling appeared to colocalize with the PML nuclear bodies. Furthermore, promyelocytic leukemia protein, RNA polymerase II (Pol II), and the Pol I-associated transcription factor SL1 could be precipitated together with hepatitis delta antigen, suggesting the association of HDV replication complex with the Pol I and Pol II transcription machineries. This conclusion was further confirmed by an in vitro replication assay. These findings provide additional evidence that HDV RNA synthesis occurs in the Pol I and Pol II transcription machineries, thus extending the capability of the cellular DNA-dependent RNA polymerases to utilizing RNA as templates.

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Caccialanza, G., C. Gandini et R. Ponci. « Direct, simultaneous determination of α-amanitin, β-amanitin and phalloidine by high-performance liquid chromatography ». Journal of Pharmaceutical and Biomedical Analysis 3, n^o 2 (janvier 1985) : 179–85. http://dx.doi.org/10.1016/0731-7085(85)80021-2.

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Job, C., D. Shire, V. Sure et D. Job. « A DNA-dependent RNA synthesis by wheat-germ RNA polymerase II insensitive to the fungal toxin α-amanitin ». Biochemical Journal 285, n^o 1 (1 juillet 1992) : 85–90. http://dx.doi.org/10.1042/bj2850085.

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Wheat-germ RNA polymerase II is able to catalyse a DNA-dependent reaction of RNA synthesis in the presence of a high concentration (1 mg/ml) of the fungal toxin alpha-amanitin. This anomalous reaction is specifically directed by single-stranded or double-stranded homopolymer templates, such as poly(dC) or poly(dC).poly(dG), and occurs in the presence of either Mn2+ or Mg2+ as the bivalent metal cofactor. In contrast, the transcription of other synthetic templates, such as poly(dT), poly(dA).poly(dT) or poly[d(A-T)] is completely abolished in the presence of 1 microgram of alpha-amanitin/ml, in agreement with well-established biochemical properties of class II RNA polymerases. Size analysis of reaction products resulting from transcription of (dC)n templates of defined lengths suggests that polymerization of RNA chains proceeds through a slippage mechanism. The fact that alpha-amanitin does not impede this synthetic reaction implies that the amatoxin interferes with the translocation of wheat-germ RNA polymerase II along the DNA template.

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Singh, Ram Kumar, Richard J. Jones, Samuel Hong, Fazal Shirazi, Hua Wang, Isere Kuiatse, Andreas Pahl et Robert Z. Orlowski. « HDP101, a Novel B-Cell Maturation Antigen (BCMA)-Targeted Antibody Conjugated to α-Amanitin, Is Active Against Myeloma with Preferential Efficacy Against Pre-Clinical Models of Deletion 17p ». Blood 132, Supplement 1 (29 novembre 2018) : 593. http://dx.doi.org/10.1182/blood-2018-99-118412.

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Abstract Background: Deletion (del) of 17p involving the p53 tumor suppressor (TP53) remains an adverse prognostic factor in multiple myeloma (MM) despite the use of novel agents as well as high-dose chemotherapy with autologous stem cell rescue. Genomic TP53 deletion can cause haploinsufficiency of nearby genes, such as RNA polymerase II subunit A (POLR2A), which ia also located on 17p13.1. We therefore hypothesized that del 17p could reduce POLR2A expression and enhance sensitivity to a-Amanitin, a potent and specific inhibitor of POLR2A and RNA polymerase III. Methods: Pre-clinical studies were performed using HDP101, a monoclonal antibody-drug conjugate (ADC) targeting BCMA linked to a-Amanitin, along with unconjugated BCMA antibody, a-Amanitin, and a non-targeting control ADC in myeloma cell line models. The latter included H929, MM1.S, and MOLP-8 TP53 wild-type (WT) lines and isogenic cells in which TP53 had been knocked out (KO) using CRISPR/Cas9 genome editing techniques. To further model del 17p and POLR2A haploinsufficiency, POLR2A expression was knocked down using shRNAs. Results: Analysis of the Multiple Myeloma Research Foundation CoMMpassSM database revealed that del 17p13 by SeqFISH was associated with a significant reduction in POLR2A expression by RNASeq (26.05431 fragments per kilobase of transcript per million mapped reads (FPKM) with WT vs. 19.2983 FPKM with del 17p13; p<0.0001). Also, patients within the lower quartile of POLR2A expression, which included those with and without del 17p, had an inferior overall survival (p<0.0011) and a trend towards a worse progression-free survival, suggesting that low POLR2A levels by themselves are an adverse feature. The POLR2A inhibiting anti-BCMA/a-Amanitin conjugate HDP101 induced a time- and dose-dependent reduction in myeloma cell viability post 96-hours of drug exposure starting at concentrations as low as in the picomolar range. This reduction with HDP101 was much greater than that seen with controls, which included a-Amanitin alone, the anti-BCMA antibody without a-Amanitin, or an anti-digoxigenin antibody conjugated to a-Amanitin. When myeloma cells were co-cultured with HS-5 human marrow stromal cells, only a-Amanitin and, to a much greater extent, HDP101 induced a loss of cell viability in myeloma cells, while the stromal cells were spared by HDP101. Loss of cell viability due to HDP101 was associated with induction of apoptosis as judged by the appearance of an increased population of cells that had a sub-G0/G1 DNA content, and that stained positively with Annexin V. Moreover, HDP101 treatment caused the appearance of cleaved fragments of Caspase 9 and 3, and loss of the mitochondrial trans-membrane potential. H929, MM1.S, and MOLP-8 TP53 KO cells were more sensitive to both HDP101 and, less potently to a-Amanitin than were their isogenic TP53 WT parental cells. As H929 cells expressed high levels of BCMA regardless of TP53 or POLR2A status, these were further examined for their sensitivity to HDP101. Notably, the preferential impact upon TP53 KO cells was associated with increased expression of Activating transcription factors -4 and -6, suggesting enhanced induction of endoplasmic reticulum stress, and at least two arms of the unfolded protein response. Interestingly, shRNA-mediated knockdown (KD) of POLR2A expression alone was sufficient to increase baseline levels of apoptosis in both H929 TP53 WT and KO cells, with a greater impact in the latter, supporting the promise of this target. Importantly, KD of POLR2A expression to further model del 17p was also associated with enhanced sensitivity to HDP101 in both the TP53 WT and KO cells compared to the control treatments. Evaluation of HDP101 in primary samples and with in vivo models is underway, and will be presented at the Annual Meeting. These studies were supported by a Leukemia & Lymphoma Society Specialized Center of Research (SCOR-12206-17). Conclusions: Our preliminary data support the possibility that del 17p myeloma may have a therapeutic vulnerability to the POLR2A inhibitor a-Amanitin through loss of TP53, and that this sensitivity is further enhanced by decreased POLR2A expression, which is common among del 17p patients. Moreover, they suggest that HDP101 is a novel potent and specific therapeutic that could show enhanced activity in the clinic especially against high-risk multiple myeloma, where effective therapies are still needed to improve patient outcomes. Disclosures Pahl: Heidelberg Pharma AG: Employment. Orlowski:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Consultancy; Genentech: Consultancy; Poseida: Research Funding; BioTheryX, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millenium Pharmaceuticals: Consultancy, Research Funding.

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Goldenthal, Michael, et James T. Nishiura. « Isolation and characterization of a mitochondrial RNA polymerase from Drosophila melanogaster ». Biochemistry and Cell Biology 65, n^o 2 (1 février 1987) : 173–82. http://dx.doi.org/10.1139/o87-022.

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A DNA-dependent RNA polymerase was solubilized from sucrose gradient isolated, DNase-treated mitochrondria of Drosophila melanogaster. The isolated mitochondria were not detectably contaminated with nuclear DNA as shown by CsCl gradient centrifugation and polylysine Kieselguhr chromatography. The detergent-solubilized RNA polymerase was sensitive to rifampicin, resistant to α-amanitin, had an apparent molecular mass of about 60 kilodaltons, and displayed a tendency to aggregate, both in crude extracts or when purified. The mitochondrial RNA polymerase could be distinguished from nuclear RNA polymerases on the basis of size, salt optima, rifampicin sensitivity, and α-amanitin resistance.

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Bakirci, Sinan, Recep Bayram, Ismail Yilmaz, Kursat Oguz Yaykasli, Sait Bayram et Ertugrul Kaya. « Purification andin vitrotoxicity of gamma amanitin ». Toxin Reviews 34, n^o 4 (2 octobre 2015) : 200–205. http://dx.doi.org/10.3109/15569543.2015.1135172.

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Butera, R., C. Locatelli, T. Coccini, V. Petrolini, D. Lonati, A. Giampreti et L. Manzo. « Urinary amanitin analysis in mushroom poisoning ». European Journal of Emergency Medicine 13, n^o 5 (octobre 2006) : A13. http://dx.doi.org/10.1097/00063110-200610000-00060.

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Lutz, Christian, Werner Simon, Susanne Werner‐Simon, Andreas Pahl et Christoph Müller. « Totalsynthese von α‐ und β‐Amanitin ». Angewandte Chemie 132, n^o 28 (28 avril 2020) : 11486–90. http://dx.doi.org/10.1002/ange.201914935.

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Bonk, Aaron J., Jon E. Anderson, Lalantha R. Abeydeera, Billy N. Day et Randall S. Prather. « Cyclin B1 levels in the porcine 4-cell stage embryo ». Zygote 10, n^o 1 (février 2002) : 79–84. http://dx.doi.org/10.1017/s0967199402002113.

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The relative quantity of cyclin B1 was determined during the development of in vitro and in vivo derived porcine 4-cell embryos by western blotting and immunolocalised during the 4-cell stage. After cleavage to the 4-cell stage cyclin B1 localised to the cytoplasm at the 5, 10, 18 and 25 time points and localised to the nucleus 33 h post 4-cell cleavage (P4CC). The relative abundance of cyclin B1 was not significantly different in in vivo or in vitro derived 4-cell stage embryos cultured in the absence of the RNA polymerase inhibitor α-amanitin. Cyclin B1 protein was not detectable in embryos cultured in medium without α-amanitin for 5, 10, 18 or 25 h P4CC followed by culture in medium with α-amanitin to 33 P4CC. These results suggest that the maternal to zygotic transition of mRNA production that occurs at the 4-cell stage of the pig embryo does not result in an increase in cyclin B1 production. In addition, cyclin B1 protein levels remained constant in the absence of embryonic genome activation at the 4-cell stage.

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Tanahashi, Masakazu, Rina Kaneko, Yukari Hirata, Makoto Hamajima, Tetsuya Arinobu, Tadashi Ogawa et Akira Ishii. « Simple analysis of α-amanitin and β-amanitin in human plasma by liquid chromatography-mass spectrometry ». Forensic Toxicology 28, n^o 2 (22 juin 2010) : 110–14. http://dx.doi.org/10.1007/s11419-010-0098-6.

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