618 research outputs found

    Twin CWG systems Final report

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    Construction, operation, and maintenance of twin control moment gyroscope system for space vehicle motion simulato

    Evolution des recouvrements forestiers et de l'Occupation des sols entre 1964 et 2002 dans la haute vallée des Ait Bouguemez (Haut Atlas Central, Maroc). Impact des modes de gestion.

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    Les espaces forestiers montagnards méditerranéens sont souvent fortement dégradés. La cause principale est la surexploitation des ressources. Au cours de l'histoire, la rareté des ressources a probablement incité les hommes à mettre en place des formes de contrôle coutumières (ou « traditionnelles ») des espaces forestiers et pastoraux. Ces régimes perdurent dans le Haut Atlas marocain sous le nom d'agdal, terme qui désigne un territoire sylvopastoral collectif soumis à des mises en défens temporaires. Ce travail vise à évaluer l'impact de cette gestion coutumière sur les dynamiques des formations boisées dans une zone de montagne, la vallée des Ait Bouguemez, à travers une analyse diachronique basée sur la comparaison de documents anciens (photographies aériennes de 1964) avec des documents récents (image satellitaire Spot 5 à très haute résolution). La méthodologie adoptée repose sur la photointerprétation visuelle des documents précités en se basant sur une charte commune d'estimation du recouvrement arboré. Deux cartes de recouvrement ont été produites pour 1964 et 2002, dont le croisement a permis d'obtenir une carte de la dynamique des peuplements. Les résultats obtenus soulignent de fortes disparités dans les dynamiques forestières selon le statut agdal ou non-agdal de la forêt. La surface forestière a diminué de 21 % en 38 ans, et le recouvrement arboré moyen sur la zone forestière chute globalement de 20 % à 18 % pendant cette période. On observe un maintien du couvert boisé en zone agdal et sa forte dégradation hors agdal dans un contexte de forte croissance démographique

    Hypotension acétyl-cholinique chez le rat

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    Auclair M., Hameau N. Hypotension acétyl-cholinique chez le Rat. In: Bulletin de l'Académie Vétérinaire de France tome 117 n°3, 1964. pp. 137-138

    Integrated Strategy for Sustainable Cattle Fever Tick Eradication in USA is Required to Mitigate the Impact of Global Change

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    The ticks Rhipicephalus (Boophilus) annulatus and R. (B.) microplus, commonly known as cattle and southern cattle tick, respectively, impede the development and sustainability of livestock industries throughout tropical and other world regions. They affect animal productivity and wellbeing directly through their obligate blood-feeding habit and indirectly by serving as vectors of the infectious agents causing bovine babesiosis and anaplasmosis. The monumental scientific discovery of certain arthropod species as vectors of infectious agents is associated with the history of research on bovine babesiosis and R. annulatus. Together, R. microplus and R. annulatus are referred to as cattle fever ticks (CFT). Bovine babesiosis became a regulated foreign animal disease in the United States of America (U.S.) through efforts of the Cattle Fever Tick Eradication Program (CFTEP) established in 1906. The U.S. was declared free of CFT in 1943, with the exception of a permanent quarantine zone in south Texas along the border with Mexico. This achievement contributed greatly to the development and productivity of animal agriculture in the U.S. The permanent quarantine zone buffers CFT incursions from Mexico where both ticks and babesiosis are endemic. Until recently, the elimination of CFT outbreaks relied solely on the use of coumaphos, an organophosphate acaricide, in dipping vats or as a spray to treat livestock, or the vacation of pastures. However, ecological, societal, and economical changes are shifting the paradigm of systematically treating livestock to eradicate CFT. Keeping the U.S. CFT-free is a critical animal health issue affecting the economic stability of livestock and wildlife enterprises. Here, we describe vulnerabilities associated with global change forces challenging the CFTEP. The concept of integrated CFT eradication is discussed in reference to global change

    E2F6 initiates stable epigenetic silencing of germline genes during embryonic development.

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    In mouse development, long-term silencing by CpG island DNA methylation is specifically targeted to germline genes; however, the molecular mechanisms of this specificity remain unclear. Here, we demonstrate that the transcription factor E2F6, a member of the polycomb repressive complex 1.6 (PRC1.6), is critical to target and initiate epigenetic silencing at germline genes in early embryogenesis. Genome-wide, E2F6 binds preferentially to CpG islands in embryonic cells. E2F6 cooperates with MGA to silence a subgroup of germline genes in mouse embryonic stem cells and in embryos, a function that critically depends on the E2F6 marked box domain. Inactivation of E2f6 leads to a failure to deposit CpG island DNA methylation at these genes during implantation. Furthermore, E2F6 is required to initiate epigenetic silencing in early embryonic cells but becomes dispensable for the maintenance in differentiated cells. Our findings elucidate the mechanisms of epigenetic targeting of germline genes and provide a paradigm for how transient repression signals by DNA-binding factors in early embryonic cells are translated into long-term epigenetic silencing during mouse development

    Otoferlin acts as a Ca2+ sensor for vesicle fusion and vesicle pool replenishment at auditory hair cell ribbon synapses

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    Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca2+-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (Otof Ala515,Ala517/Ala515,Ala517) with lower Ca2+-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca2+ currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced. Lower Ca2+ sensitivity and delay of the fast and sustained components of synaptic exocytosis were revealed by membrane capacitance measurement upon modulations of intracellular Ca2+ concentration, by varying Ca2+ influx through voltage-gated Ca2+-channels or Ca2+ uncaging. Otoferlin thus functions as a Ca2+ sensor, setting the rates of primed vesicle fusion with the presynaptic plasma membrane and synaptic vesicle pool replenishment in the IHC active zone

    Proteomic Insights into the Hidden World of Phloem Sap Feeding

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    The physical interface between a phloem-feeding insect and its host plant is a single cell buried deep within the plant tissue. As such, the molecular interactions between these notorious agricultural pests and the crop plants upon which they feed are diffi cult to study. ‘Omic’ technologies have proved crucial in revealing some of the fascinating detail of the molecular interplay between these partners. Here we review the role of proteomics in identifying putative components of the secreted saliva of phloem-feeding insects, particularly aphids, and discuss the limited knowledge concerning the function of these proteins

    Response to gefitinib and erlotinib in Non-small cell lung cancer: a retrospective study

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    <p>Abstract</p> <p>Background</p> <p>In Non-small cell lung cancer (NSCLC), an overactive epidermal growth factor receptor (EGFR) pathway is a component of the malignant phenotype. Two tyrosine kinase inhibitors (TKIs) of EGFR, gefinitib and erlotinib, have been used with variable benefit.</p> <p>Methods</p> <p>We have analyzed outcome data of a population of NSCLC patients that received these TKIs to determine the benefit derived and to define the clinical and molecular parameters that correlate with response. Tumor tissue from a subgroup of these patients was analyzed by immunohistochemistry to measure the expression level of EGFR and four activated (phosphorylated) members of the pathway, pEGFR, pERK, pAKT, and pSTAT3.</p> <p>Results</p> <p>Erlotinib was slightly superior to gefitinib in all measures of response, although the differences were not statistically significant. The most robust clinical predictors of time to progression (TTP) were best response and rash (p < 0.0001). A higher level of pEGFR was associated with longer TTP, while the total EGFR level was not associated with response. Higher levels of pAKT and pSTAT3 were also associated with longer TTP. In contrast, a higher level of pERK1/2 was associated with shorter TTP.</p> <p>Conclusion</p> <p>These observations suggest the hypothesis that tumor cells that have activated EGFR pathways, presumably being utilized for survival, are clinically relevant targets for pathway inhibition. An accurate molecular predictive model of TKI response should include activated members of the EGFR pathway. TKIs may be best reserved for tumors expressing pEGFR and pAKT or pSTAT, and little pERK. In the absence of molecular predictors of response, the appearance of a rash and a positive first scan are good clinical indicators of response.</p
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