INTRAMARGINAL VEINED LAURACEAE LEAVES FROM THE ALBIAN–CENOMANIAN OF CHARENTE-MARITIME (WESTERN FRANCE)

Abstract:  Eucalyptolaurus depreii gen. et sp. nov. is proposed for angiosperm leaves newly collected from uppermost Albian – lowermost Cenomanian of Charente-Maritime (western France). They consist of simple, narrow, elongate laminas with entire margins and intramarginal veins. The epidermal cells of adaxial cuticle shows small, rounded, blunt papillae outward that protrude inward and fuse together as rolls along and parallel to the margins, while the adaxial cuticle bears brachyparacytic stomatal apparatus that exhibit sunken guard cells and hair bases consisting of a thick-walled pore surrounded by radially arranged differentiated cells. Resin bodies occur inside the mesophyll. These characters closely resemble the lauroid taxa ' Myrtophyllum ' and Pandemophyllum from the Cenomanian of the Czech Republic and Dakota (USA) respectively. The narrow angle of basilaminar secondaries and the whole suite of features in the guard cells (sunken guard cells embedded into subsidiary cells and stomatal ledges) strongly support close affinity with the Lauraceae. From the Cenomanian lauraceous reproductive organs and their related leaves already showed high disparity and diversity. In addition they displayed a broad ecological range from freshwater floodplains to brackish swamps. This combined to high diversity of reproductive organs suggest ecological radiation of Lauraceae by the Cenomanian.     

Fractionation of Sporogonial Stages of the Microsporidian Encephalitozoon cuniculi by Percoll® Gradients

Microsporidia are obligate intracellular parasites that are increasingly recognized as a cause of opportunistic infections in immunocompromised individuals. Encephalitozoon cuniculi has been identified in humans with AIDS and infects a wide range of mammalian hosts. Little is known about the metabolic processes that regulate growth and replication of microsporidia. Examination of the individual stages of development will facilitate such studies and reveal possible targets for drug therapy. The purpose of this study was to fractionate and purify stages of the microsporidian life cycle. Encephalitozoon cuniculi were cultured in RK-13 cells. The tissue supernatants containing multiple parasite stages, empty microsporidial husks and host cell debris were collected, washed, and subjected to differential centrifugation in 80% stock isotonic Percoll. Transmission electron microscopy and SDS-polyacrylamide gel electrophoresis were used to compare the content and purity of each fraction. Mature spores formed a band at a density of approximately 1.138 g/ml. Sporoblasts were found at densities between 1.102 g/ml and 1.119 g/ml. A mixture of sporonts, sporoblasts, microsporidial husks, and cell debris remained at the top of the gradient and additional centrifugation in 30% and 50% Percoll resulted in separation of these stages. These results represent the first step toward fractionating stages of microsporidia infecting humans.     

Analysis of cytosolic isocitrate dehydrogenase and glutathione reductase 1 in photoperiod‐influenced responses to ozone using Arabidopsis knockout mutants

Oxidative stress caused by ozone (O₃) affects plant development, but the roles of specific redox‐homeostatic enzymes in O₃ responses are still unclear. While growth day length may affect oxidative stress outcomes, the potential influence of day length context on equal‐time exposures to O₃ is not known. In Arabidopsis Col‐0, day length affected the outcome of O₃ exposure. In short‐days (SD), few lesions were elicited by treatments that caused extensive lesions in long days (LD). Lesion formation was not associated with significant perturbation of glutathione, ascorbate, NADP(H) or NAD(H). To investigate roles of two genes potentially underpinning this redox stability, O₃ responses of mutants for cytosolic NADP‐isocitrate dehydrogenase (icdh) and glutathione reductase 1 (gr1) were analysed. Loss of ICDH function did not affect O₃‐induced lesions, but slightly increased glutathione oxidation, induction of other cytosolic NADPH‐producing enzymes and pathogenesis‐related gene 1 (PR1). In gr1, O₃‐triggered lesions, salicylic acid accumulation, and induction of PR1 were all decreased relative to Col‐0 despite enhanced accumulation of glutathione. Thus, even at identical irradiance and equal‐time exposures, day length strongly influences phenotypes triggered by oxidants of atmospheric origin, while in addition to its antioxidant function, the GR‐glutathione system seems to play novel signalling roles during O₃ exposure.     

Sur l'action cytonarcotique des sels de nickel chez Paramecium caudatum Ehrb.

SYNOPSIS. Cytonarcotic action of Ni-chloride Ni-sulfate and Ni-nitrate is studied with mating types C and D French variety II of P. caudatum = XV and XVI American variety 8. The time which is necessary to make the ciliates motionless is proportional to Ni ion number in solution, but, in any case, there is a minimum time for narcosis. Mating types have very different sensitivity. C is more sensitive than D. Ba⁺⁺ and Ca⁺⁺ strongly antagonize the action of Ni⁺⁺. This antagonism, only biological, depends on the simultaneous presence of the ions in solution and has maximum value when the ions are in definite and constant proportion. Formation of digestive vacuoles involves reactions which make the ciliate resistant to Ni probably by decrease of membrane permeability. After narcosis, about twenty generations must pass before the rate of multiplication is again normal.     

The Truth from the Body: Medical Certificates as Ultimate Evidence for Asylum Seekers

Whether through traditional law or modern torture, the body has always been a privileged site on which to demonstrate the evidence of power. But for immigrants, the poor, and, more generally, the dominated—all of whom have to prove their eligibility to certain social rights—it has also become the place that displays the evidence of truth. In France, as immigration control increases, asylum seekers are more and more submitted to the evaluation of their physical sequels and psychic traumas, as if their autobiographical accounts were not sufficient. In this article, we show how nongovernmental organizations (NGOs) deal with the dilemmas posed by this situation, how they develop protocols standardizing their expertise, and how their medical authority progressively substitutes itself for the asylum seekers' word. In this process of objectification, it is the experience of the victims as political subjects that is progressively erased.