84 research outputs found
Production and Utilization of Multi-purpose Fodder Shrubs and Trees in West Asia, North Africa and the Sahel
A Major Role for the Plasmodium falciparum ApiAP2 Protein PfSIP2 in Chromosome End Biology
The heterochromatic environment and physical clustering of chromosome ends at the nuclear periphery provide a functional and structural framework for antigenic variation and evolution of subtelomeric virulence gene families in the malaria parasite Plasmodium falciparum. While recent studies assigned important roles for reversible histone modifications, silent information regulator 2 and heterochromatin protein 1 (PfHP1) in epigenetic control of variegated expression, factors involved in the recruitment and organization of subtelomeric heterochromatin remain unknown. Here, we describe the purification and characterization of PfSIP2, a member of the ApiAP2 family of putative transcription factors, as the unknown nuclear factor interacting specifically with cis-acting SPE2 motif arrays in subtelomeric domains. Interestingly, SPE2 is not bound by the full-length protein but rather by a 60kDa N-terminal domain, PfSIP2-N, which is released during schizogony. Our experimental re-definition of the SPE2/PfSIP2-N interaction highlights the strict requirement of both adjacent AP2 domains and a conserved bipartite SPE2 consensus motif for high-affinity binding. Genome-wide in silico mapping identified 777 putative binding sites, 94% of which cluster in heterochromatic domains upstream of subtelomeric var genes and in telomere-associated repeat elements. Immunofluorescence and chromatin immunoprecipitation (ChIP) assays revealed co-localization of PfSIP2-N with PfHP1 at chromosome ends. Genome-wide ChIP demonstrated the exclusive binding of PfSIP2-N to subtelomeric SPE2 landmarks in vivo but not to single chromosome-internal sites. Consistent with this specialized distribution pattern, PfSIP2-N over-expression has no effect on global gene transcription. Hence, contrary to the previously proposed role for this factor in gene activation, our results provide strong evidence for the first time for the involvement of an ApiAP2 factor in heterochromatin formation and genome integrity. These findings are highly relevant for our understanding of chromosome end biology and variegated expression in P. falciparum and other eukaryotes, and for the future analysis of the role of ApiAP2-DNA interactions in parasite biology
Triterpenos pentacĂclicos e esterĂłides da casca do uchi (Sacoglottis uchi, Humiriaceae)
The ethanol extract from stem bark of Sacoglottis uchi Huber (popularly known as \x93uchi\x94 in the Amazon Region) was submitted to chromatographic fractionation. The dichloromethane fractions provided the pentacyclic triterpene 3-oxo-friedelin (1). The dichloromethane:methanol fractions provided the pentacyclic triterpenes pseudotaraxasterol (2), lupeol (3), a-amyrin (4), betulin (5), and methyl 2Ă,3Ă-dihydroxy-urs-12-en-28-oate (6) and a mixture of the steroids sitosterol (7) and stigmasterol (8). Their chemical structures were determined by NMR spectroscopy and comparison with spectroscopic data from the literature. All compounds are described for the first time in this species.O extrato etanĂłlico da casca do caule de Sacoglottis uchi Huber (conhecida popularmente como \x93uchi\x94 na AmazĂŽnia) foi submetido a fracionamento cromatogrĂĄfico. As fraçÔes eluĂdas com diclorometano forneceram o triterpeno pentacĂclico 3-oxo-friedelina (1). As fraçÔes em diclorometano:metanol forneceram os triterpenos pentacĂclicos pseudotaraxasterol (2), lupeol (3), a-amirina (4), betulina (5) e 2Ă,3Ă-di-hidroxi-urs-12-en-28-oato de metila (6), alĂ©m de uma mistura dos esterĂłides sitosterol (7) e estigmasterol (8). Suas estruturas quĂmicas foram determinadas por espectroscopia de RMN e comparação com os dados espectroscĂłpicos descritos na literatura. Todas as substĂąncias isoladas sĂŁo descritas pela primeira vez nesta espĂ©cie
Aplicação da anĂĄlise multivariada em avaliaçÔes de divergĂȘncia genĂ©tica atravĂ©s de marcadores moleculares dominantes em plantas medicinais
Atividade repelente e inseticida do Ăłleo essencial de carqueja doce sobre o caruncho do feijĂŁo
Essential oils of Cunila galioides and Origanum majorana as anesthetics for Rhamdia quelen: efficacy and effects on ventilation and ionoregulation
Low-field and high-field characterization of THUNDER actuators
Abstract. THUNDER (THin UNimorph DrivER) actuators are pre-stressed piezoelectric devices developed at NASA Langley Research Center (LaRC) that exhibit enhanced strain capabilities. As a result, they are of interest in a variety of aerospace applications. Characterization of their performance as a function of electric field, temperature and frequency is needed in order to optimize their operation. Towards that end, a number of THUNDER devices were obtained from FACE International Co. with a stainless steel substrate varying in thickness from 1 mil to 20 mils. The various devices were evaluated to determine low-field and high-field displacement as well as the polarization hysteresis loops. The thermal stability of these drivers was evaluated by two different methods. First, the samples were thermally cycled under electric field by systematically increasing the maximum temperature from 25°C to 200°C while the displacement was being measured. Second, the samples were isothermally aged at 0°C, 50°C, 100°C, and 150°C in air, and the isothermal decay of the displacement was measured at room temperature as a function of time. Key words. piezoelectric, pre-stressed ceramic, hysteresis, temperature effect, isothermal aging Subject classification. Materials 1. Introduction. This work describes the results of a characterization study of THin UNimorph-like DrivER (THUNDER) actuators to determine the effects of metal thickness on free displacement at both sub-switching an
Concours dâinternat des HĂŽpitaux de LomĂ© de 1974 Ă 2006 : etat des lieux
Objectif: Faire lâĂ©tat des lieux du concours dâinternat des hĂŽpitaux de LomĂ©MĂ©thodologie: Etude transversale descriptive rĂ©alisĂ©e Ă la facultĂ© des sciences de la santĂ© de l'universitĂ© de LomĂ© et dans les centres hospitaliers universitaires de LomĂ©. Elle a consistĂ© au dĂ©pouillement des documents et des archives du concours dâinternat des hĂŽpitaux de LomĂ© et en des entretiens semi-directs avec un Ă©chantillon dâindividus ayant un rapport avec lâinternat des hĂŽpitaux de LomĂ©RĂ©sultats: Vingt-quatre sessions ont Ă©tĂ© organisĂ©es en 33 ans. Le concours Ă©tait ouvert aux Ă©tudiants ayant validĂ© la 5Ăš annĂ©e dâĂ©tudes mĂ©dicales. 425 candidatures ont Ă©tĂ© enregistrĂ©es : 0,08% de filles, 51,29% dâĂ©tudiants de 6Ăšme annĂ©e et 15,33% dâĂ©tudiants militaires. Au total 135 internes ont Ă©tĂ© nommĂ©s au cours des 24 sessions organisĂ©es (87,41% de sexe masculin). Les Ă©tudiants de sixiĂšme annĂ©e (54,81%) et les civils (77,78%) Ă©taient les plus reprĂ©sentĂ©s. La spĂ©cialisation des internes sâest faite au Togo dans la majoritĂ© des cas mais aussi dans certains pays africains (SĂ©nĂ©gal, CĂŽte dâIvoire, BĂ©nin). Les internes se spĂ©cialisaient plus en chirurgie (33,6%) et en gynĂ©co-obstĂ©trique (19,2%). Vingt-six anciens internes des hĂŽpitaux ont optĂ© pour la carriĂšre universitaire. Une forte Ă©migration des anciens internes a Ă©tĂ© notĂ©e : 80% se trouvaient en France.Conclusion: Lâinternat des hĂŽpitaux de LomĂ© mĂ©rite des rĂ©formes prenant en compte les progrĂšs de la MĂ©decine, les besoins rĂ©els de lâexercice sur le terrain, et lâavenir Ă rĂ©server aux laurĂ©atsMots clĂ©s: Internat des hĂŽpitaux- LomĂ©English Title: Lome Hospital internship competition from 1974 to 2006: the situation todayEnglish AbstractObjective: To review the state of the hospital internship competition in LomĂ©Methodology: Descriptive cross-sectional study conducted at the Faculty of Health Sciences of the University of Lome and in the teaching hospitals of Lome. It consisted of counting the documents and archives of the hospital internship competition of LomĂ© and also semi-direct interviews with a sample of individuals related to the Lome hospital internship.Results: Twenty-four sessions were organized in 33 years. The competition was open to students who have validated the 5th year of medical studies. 425 applications were registered: 0.08% of girls, 51.29% of 6th year students and 15.33% of military students. A total of 135 interns were appointed during the 24 sessions organized (87.41% boys). Sixth year students (54.81%) and civilians (77.78%) were the most represented. The specialization of interns was done in Togo in the majority of cases but also in some African countries (Senegal, Ivory Coast, Benin). The interns specialized more in surgery (33.6%) and obstetrics and gynecology (19.2%). Twenty-six former hospital interns opted for the university career. A strong emigration of former interns was noted: 80% were in France.Conclusion: Lome hospital internship deserves reforms taking into account the progress of Medicine, the actual needs of the field exercise, and the future to be reserved for the laureatesKeywords: Hospitals internship, Lom
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