Le petit fidâ'î : L'enfant dans la lutte pour la cause palestinienne et autres formes de résistances dans la littérature pour la jeunesse arabe (Égypte, Syrie, Liban) depuis 1967

Au lendemain de la naksa, la défaite " catastrophique " de 1967, les sociétés syrienne, égyptienne et libanaise s'engagent dans l'écriture et l'illustration pour les enfants, et ce faisant se décrivent et dessinent leur avenir idéalisé. La création arabe en littérature pour la jeunesse qui naît et se développe dans les années 70 est profondément animée par le souffle idéologique de son temps : elle est panarabe, socialiste ou ba'thiste, engagée dans la lutte pour la cause palestinienne. Elle pose les jalons structurels, thématiques et graphiques qui influencent et inspirent la production contemporaine. Avant 1967, le champ de l'édition de livres pour enfants n'était pas désert mais il était surtout scolaire, parsemé de revues traduites et vendues dans la rue qui marquèrent profondément les mémoires. En revanche, le champ de la création arabe et des albums de littérature pour la jeunesse demeurait presque inexploré

Effect of Sequential Isoproturon Pulse Exposure on Scenedesmus vacuolatus

Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 μg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 μg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC50 prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicide

Evidence of unreduced gamete production from interspecific crosses between Gossypium hirsutum and G. herbaceum

In order to analyze the gene flow between the allotetraploid cultivated cotton (Gossypium hirsutum, AADD, 2n=52) and the wild diploid (G. herbaceum, AA, 2n=26), the possibility of natural hybridization between these two cotton species has been investigated. In fact, in South Africa and particularly in the KwaZulu Natal Province, where commercialisation of transgenic Bt cotton began in 1998, a wild species (G. herbaceum) is neighbouring from the cultivated cotton fields. From reciprocal crosses performed without emasculation between G herbaceum used as female or male and G hirsutum, 148 and 335 plants respectively, have been analyzed. Neither examination of the morphological characteristics nor the flow cytometry analysis of the 335 plants resulting from the cross G hirsutum x G herbaceum, have shown any to be hybrid plants. For the cross G herbaceum x G hirsutum, three plants have shown a hybrid phenotype. Analysis of DNA content by flow cytometry and morphological traits, have clearly shown that two of them were triploid (AAD). The third one exhibited a value in flow cytometry slightly higher than G hirsutum. In addition some morphological characteristics (plant morphology, presence and size of petal spots, leaf shape...) have led us to conclude that this plant is AAAD and was the result of a fecundation with unreduced gamete AA from the female G herbaceum parent. Fluorescent In Situ Hybridization (FISH), and meiotic behaviour have confirmed this hypothesis. This is, to our knowledge, the first description of the occurrence of a non-reductional meiosis in the species G. herbaceum. This plant material could provide a useful tool for the study of the expression of genes duplicated in the A and D cotton genome. The possibility of obtaining an interspecific hybrid between cultivated and diploid wild cotton through fertilization with an unreduced gamete raises the question of its evolution in natural populations. (Texte intégral

Risk of herbicide mixtures as a key parameter to explain phytoplankton fluctuation in a great lake: the case of Lake Geneva, Switzerland

Mixture risk assessment predictions have rarely been confronted with biological changes observed in the environment. In this study, long-term monitoring of a European great lake, Lake Geneva, provides the opportunity to assess to what extent the predicted toxicity of herbicide mixtures explains the changes in the composition of the phytoplankton community next to other classical limnology parameters such as nutrients. To reach this goal, the gradient of the mixture toxicity of 14 herbicides regularly detected in the lake was calculated using concentration addition and response addition models. A temporal gradient of toxicity was observed which decreased from 2004 to 2009. Redundancy analysis and partial redundancy analysis showed that this gradient explains a significant portion of the variation in phytoplankton community composition with and without having removed the effect of all other co-variables. Moreover, species that are significantly influenced, positively or negatively, by the decrease of toxicity in the lake over time are highlighted. It can be concluded that the herbicide mixture toxicity is one of the key parameters to explain phytoplankton changes in Lake Genev

Diagnostic des eaux de surface. Application du système modulaire gradué au Boiron de Morges

Les variations hydro-climatiques et anthropiques actuelles et prévues dans le futur interrogent sur l’évolution de l’état écologique des cours d’eau. Il est donc crucial de développer des outils prenant en compte les dimensions quantitatives et qualitatives des ressources en eau. C’est le cas du système modulaire gradué proposé par l’Office fédéral de l’environnement. Cet article présente un retour d’expérience sur la mise en oeuvre de ce système, appliqué au Boiron de Morges, et sur sa capacité à identifier la variabilité spatio-temporelle des enjeux écologiques

Toxicity of Tamoxifen on Daphnia pulex

Daphnia pulex is a water flea considered an environmental indicator species. In this experiment we exposed Daphnia to Tamoxifen in low or high concentrations, dissolved in dimethyl sulfoxide with water, and we measured the amount of proteins at day 2 and 7. With the R package maSigPro we selected proteins changing significantly over time among the four experimental groups and we developed a cluster analysis for the behavior of profiles over time, to understand which and how these specific proteins change according to the treatment received. The information obtained from this study represents an important first step towards characterizing patterns specific to environmental contaminants