49 research outputs found
Decreased MCM2-6 in Drosophila S2 cells does not generate significant DNA damage or cause a marked increase in sensitivity to replication interference.
A reduction in the level of some MCM proteins in human cancer cells (MCM5 in U20S cells or MCM3 in Hela cells) causes a rapid increase in the level of DNA damage under normal conditions of cell proliferation and a loss of viability when the cells are subjected to replication interference. Here we show that Drosophila S2 cells do not appear to show the same degree of sensitivity to MCM2-6 reduction. Under normal cell growth conditions a reduction of >95% in the levels of MCM3, 5, and 6 causes no significant short term alteration in the parameters of DNA replication or increase in DNA damage. MCM depleted cells challenged with HU do show a decrease in the density of replication forks compared to cells with normal levels of MCM proteins, but this produces no consistent change in the levels of DNA damage observed. In contrast a comparable reduction of MCM7 levels has marked effects on viability, replication parameters and DNA damage in the absence of HU treatment
A quantitative synthesis of the medicinal ethnobotany of the Malinké of Mali and the Asháninka of Peru, with a new theoretical framework
<p>Abstract</p> <p>Background</p> <p>Although ethnomedically and taxonomically guided searches for new medicinal plants can improve the percentage of plants found containing active compounds when compared to random sampling, ethnobotany has fulfilled little of its promise in the last few decades to deliver a bounty of new, laboratory-proven medicinal plants and compounds. It is quite difficult to test, isolate, and elucidate the structure and mechanism of compounds from the plethora of new medicinal plant uses described each year with limited laboratory time and resources and the high cost of clinical trials of new drug candidates.</p> <p>Methods</p> <p>A new quantitative theoretical framework of mathematical formulas called "relational efficacy" is proposed that should narrow down this search for new plant-derived medicines based on the hypothesis that closely related plants used to treat closely related diseases in distantly related cultures have a higher probability of being effective because they are more likely to be independent discoveries of similar plant compounds and disease mechanisms. A prerequisite to this hypothesis, the idea that empirical testing in traditional medicine will lead to choosing similar medicinal plants and therefore the medicinal flora of two distant cultures will prove to be more similar than their general flora, is tested using resampling statistics on cross-cultural field data of the plants used by the MalinkĂ© of Mali and the Asháninka of Peru to treat the diseases malaria, African sleeping sickness, Chagas' disease, leishmaniasis, diabetes, eczema, asthma, and uterine fibroids.</p> <p>Results</p> <p>In this case, the similarity of the medicinal floras is found to be significantly greater than the similarity of the general floras, but only when the diseases in question are grouped into the categories of parasitic and autoimmune diseases.</p> <p>Conclusion</p> <p>If the central theoretical framework of this hypothesis is shown to be true, it will allow the synthesis of medicinal plant information from around the world to pinpoint the species with the highest potential efficacy to take into the laboratory and analyze further, ultimately saving much field and laboratory time and resources.</p> <p><b>Spanish abstract</b></p> <p>Las bĂşsquedas que utilizan la etnomedicina y la taxonomĂa para descubrir nuevas plantas medicinales, pueden aumentar la probabilidad de Ă©xito de encontrar compuestos quĂmicos activos en plantas, en comparaciĂłn con las bĂşsquedas aleatorias. A pesar de lo anterior, en las Ăşltimas dĂ©cadas, la etnobotánica no ha cumplido con las expectativas de proveer numerosas plantas medicinales y quĂmicos nuevos una vez examinados en el laboratorio. Cada año se describen una plĂ©tora de plantas medicinales y sus usos, sin embargo las limitaciones de tiempo y recursos en los laboratorios, unidos al alto coste de los ensayos clĂnicos de las drogas potenciales, hacen muy difĂcil probar, aislar, y elucidar la estructura y el mecanismo de los compuestos de estas plantas. Se propone un nuevo marco teĂłrico cuantitativo cuyo fin es focalizar la bĂşsqueda de nueva plantas medicinales. Este marco teĂłrico está basado en la hipĂłtesis que las plantas cercanamente relacionadas, usadas para tratar enfermedades cercanamente relacionadas en culturas distantemente relacionadas, tienen una eficacia potencial más alta, debido a que es más probable que estos hallazgos sean descubrimientos independientes de compuestos quĂmicos similares. Parte de esta hipĂłtesis, que las escogencias racionales se hacen para elegir plantas medicinales similares y que la flora medicinal de dos culturas distantes es más similar que su flora general, se probĂł usando mĂ©todos estadĂsticos de remuestreo con datos de campo de la comunidad MalinkĂ© de MalĂ y de la Asháninka de PerĂş, y las enfermedades de paludismo, enfermedad africana del sueño, enfermedad de Chagas, leishmania, diabetes, eczema, asma, y fibromas uterinos. Se encontrĂł, en este caso, que la similitud de las floras medicinales es significativamente mayor a la similitud de las floras generales, solamente cuando las enfermedades analizadas se agruparon en las categorĂas de enfermedades parasitarias y enfermedades autoinmunes. Si se demostrara que las otras partes de esta hipĂłtesis son ciertas, se podrĂa sintetizar la informaciĂłn sobre plantas medicinales alrededor del mundo, para establecer asĂ las plantas potencialmente más eficaces para llevarlas al laboratorio y analizarlas más profundamente.</p> <p><b>French abstract</b></p> <p>Par rapport aux recherches menĂ©es de façon alĂ©atoire, les recherches effectuĂ©es par des critères ethnobotaniques et taxonomiques ont de meilleures chances Ă dĂ©couvrir de nouvelles plantes mĂ©dicinales Ă produit chimique actifs. Pendant les dernières dĂ©cennies pourtant, l'ethnobotanique a rĂ©alisĂ© peu de ces promesses Ă rĂ©vĂ©ler un grand nombre de plantes mĂ©dicinales et de nouveaux produits chimiques, testĂ©s au laboratoire. Avec les ressources limitĂ©es pour la recherche au laboratoire et le coĂ»t Ă©levĂ© des Ă©preuves cliniques pour trouver de nouveaux candidats aux mĂ©dicaments, il est difficile d'Ă©tudier, d'isoler et d'Ă©lucider la structure et le mĂ©canisme des produits chimiques de chacune des nombreuses plantes mĂ©dicinales (et les utilisations de ces plantes) dĂ©crites chaque annĂ©e. Nous proposons une nouvelle technique thĂ©orique et quantitative pour prĂ©ciser la recherche de nouvelles plantes mĂ©dicinales; elle est basĂ©e sur l'hypothèse que les plantes Ă©troitement apparentĂ©es, employĂ©es pour traiter les maladies Ă©troitement apparentĂ©es dans les cultures très Ă©loignĂ©es les unes des autres, ont une potentialitĂ© d'efficacitĂ© supĂ©rieure parce qu'elles reprĂ©sentent la dĂ©couverte indĂ©pendante des propriĂ©tĂ©s chimiques semblables des plantes. Une partie de cette hypothèse-qui dĂ©montre que la sĂ©lection des plantes mĂ©dicinales semblables est un choix rationnel et qu'il y a davantage de ressemblance dans la flore mĂ©dicinale de deux cultures Ă©loignĂ©es que dans leur flore gĂ©nĂ©rale-est examinĂ©e par un re-Ă©chantillonnage des donnĂ©es de recherches effectuĂ©es parmi les MalinkĂ© au Mali et les Asháninka au PĂ©rou, en particulier sur la malaria, la maladie africaine du sommeil, la maladie de Chagas, la leishmania, le diabète, l'eczĂ©ma, l'asthme et les fibromes utĂ©rins. Dans ces cas prĂ©cis, la similitude de la flore mĂ©dicinale s'avère sensiblement plus grande que la similitude de la flore gĂ©nĂ©rale, mais seulement quand les maladies en question sont regroupĂ©es ensemble comme maladies parasitaires et auto-immunitaires. Si cette hypothèse est prouvĂ©e, elle permettra la synthèse des informations recueillies sur les plantes mĂ©dicinales du monde entier pour en sĂ©lectionner de façon plus prĂ©cise celles qui sont les plus efficaces et qui mĂ©ritent analyse plus approfondie au laboratoire.</p> <p><b>Asháninka abstract</b></p> <p>Aayiantyarori iròpero aavintane, ontzimatye ancovacovatero ayotero ovaqueraripaye incashi iyoyetziri ashaninka, ayotzityaro aajatzi iyotane viracocha paitachari "quimica" ancantero aaca oshintsinka inchashipaye. Atziri yotacotzirori cametsa, ishtoriajacotzirori iyotane ashaninkapaye te iroñà rantero maaroni ocaratzi yamenacotaqueri laboratorioki. Aaviantyarori cametsa, ayotacotero aavintarontsiyetatsiri osamani antzimaventero ishtoriatacotaro, aajatzi osheki opinata ampinaventero aparopaye inchashi, acoviriqui ayotacotero, osaretsikipaye. Tzimatsi ovaquerari quenquishiriantsitatsiri ero opinata osheki ashitoriatacotero aparopaye inchashi, asampiyetatyrey pashinipaye atziri saicatsiri intaina puitarika inchasshi yavintari, ajatzirica oshiyaro ayotzi aaca, quemetachari atziri saikatsiri nampitsiki malinke aajatzi ishiyari ashaninka saicatsiri peruki, tzimatsi inchashi aajatzi yaavintari osheki okamètsatzi aririka anteri mantsiyarentsi icantaitziri ompetarentsi catsirentsi, pochokirentsi, patsarontsi(matatsi) ashipetate maaroni, ampochavathate, ancainikentsite, oncatsithakite tsinani. Aririka añaker aajatzi ahiyaro inchashi yaavintayetari pashinipaye atziri intainasatzi irdotake ahitoriatacoperoteri anĂ ashityard aavintarontsi ovamairiri shithanentsi, onĂ shitaavintarontsi tzicaacoventairi ero antane mantsiyarentsi. Omanperotatyarica iròperotzi avintarontsi, oshitovake laboratorioki aritaque iyoitanaquero maaroni quipatsiki iroperori avintarontsi.</p
Analyzing the dynamics of DNA replication in Mammalian cells using DNA combing
How cells duplicate their chromosomes is a key determinant of cell identity and genome stability. DNA replication can initiate from more than 100,000 sites distributed along mammalian chromosomes, yet a given cell uses only a subset of these origins due to inefficient origin activation and regulation by developmental or environmental cues. An impractical consequence of cell-to-cell variations in origin firing is that population-based techniques do not accurately describe how chromosomes are replicated in single cells. DNA combing is a biophysical DNA fiber stretching method which permits visualization of ongoing DNA synthesis along Mb-sized single-DNA molecules purified from cells that were previously pulse-labeled with thymidine analogues. This allows quantitative measurements of several salient features of chromosome replication dynamics, such as fork velocity, fork asymmetry, inter-origin distances, and global instant fork density. In this chapter we describe how to obtain this information from asynchronous cultures of mammalian cells
Measurement of aroma coumpound self-diffusion in food models by DOSY
International audienc
Specific splicing defects in S. pombe carrying a degron allele of the Survival of Motor Neuron gene
Spinal muscular atrophy results from deletions or mutations in the survival of motor neuron (SMN1) gene. The SMN protein has an essential role in the biogenesis of spliceosomal snRNPs, but the link between a defect in this process and specific splicing inhibition of pre-mRNAs has not been established. In this study, we report the construction of a temperature-degron (td) allele of the Schizosaccharomyces pombe SMN protein and show that its depletion at 37 degrees C affects splicing and formation of U1, U2, U4 and U5 snRNPs, but not of U6 and U3 ribonucleoproteins. The function of the tdSMN allele in snRNP assembly is already perturbed at 25 degrees C, suggesting a deleterious effect of the tag at this temperature. Using a genome-wide approach, we report that introns react unequally to lower levels of snRNPs in tdSMN cells and that increasing the length of the polypyrimidine tract can improve the splicing efficiency of some, but not all, affected introns. Altogether, our results suggest that the defects observed in tdSMN fission yeast cells mimic splicing deficits observed in SMN-deficient metazoan cells
Measurement of aroma coumpound self-diffusion in food models by DOSY
International audienc
Metabolic and Environmental Conditions Determine Nuclear Genomic Instability in Budding Yeast Lacking Mitochondrial DNA
International audienceMitochondrial dysfunctions are an internal cause of nuclear genome instability. Because mitochondria are key regulators of cellular metabolism, we have investigated a potential link between external growth conditions and nuclear chromosome instability in cells with mitochondrial defects. Using Saccharomyces cerevisiae, we find that cells lacking mitochondrial DNA (rho0 cells) have a unique feature, with nuclear chromosome instability that occurs in non-dividing cells and strongly fluctuates depending on the cellular environment. Calorie restriction, lower growth temperatures, growth at alkaline pH, anti-oxidants or presence of nearby wild type cells all efficiently stabilize nuclear genomes of rho0 cells, while high glucose and ethanol boost instability. In contrast, other respiratory mutants that still possess mitochondrial DNA (RHO+) keep fairly constant instability rates under the same growth conditions, like wild type or other RHO+ controls. Our data identify mitochondrial defects as an important driver of nuclear genome instability influenced by environmental factors