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Sent on Saturday, 2010 Sep 25Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| PubMed Results |
| 1. | PLoS One. 2010 Aug 26;5(8). pii: e12443.Disruption of the Lipid-Transporting LdMT-LdRos3 Complex in Leishmania donovani Affects Membrane Lipid Asymmetry but Not Host Cell Invasion.Weingärtner A, Drobot B, Herrmann A, Sánchez-Cañete MP, Gamarro F, Castanys S, Günther Pomorski T.Institute of Biology and Biophysics, Humboldt-University Berlin, Berlin, Germany. AbstractMaintenance and regulation of the asymmetric lipid distribution across eukaryotic plasma membranes is governed by the concerted action of specific membrane proteins controlling lipid movement across the bilayer. Here, we show that the miltefosine transporter (LdMT), a member of the P4-ATPase subfamily in Leishmania donovani, and the Cdc50-like protein LdRos3 form a stable complex that plays an essential role in maintaining phospholipid asymmetry in the parasite plasma membrane. Loss of either LdMT or LdRos3 abolishes ATP-dependent transport of NBD-labelled phosphatidylethanolamine (PE) and phosphatidylcholine from the outer to the inner plasma membrane leaflet and results in an increased cell surface exposure of endogenous PE. We also find that promastigotes of L. donovani lack any detectable amount of phosphatidylserine (PS) but retain their infectivity in THP-1-derived macrophages. Likewise, infectivity was unchanged for parasites without LdMT-LdRos3 complexes. We conclude that exposure of PS and PE to the exoplasmic leaflet is not crucial for the infectivity of L. donovani promastigotes. |
| PMID: 20865154 [PubMed - in process] | |
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| 2. | Nucleic Acids Res. 2010 Sep 22. [Epub ahead of print]Centromere-associated topoisomerase activity in bloodstream form Trypanosoma brucei.Obado SO, Bot C, Echeverry MC, Bayona JC, Alvarez VE, Taylor MC, Kelly JM.Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK, Laboratorio de Parasitologia - Facultad de Medicina, Universidad Nacional de Colombia-Sede, Bogota, Colombia and Instituto de Investigaciones Biotecnologicas, Universidad Nacional de General San Martin, Avenida General Paz 5445, INTI, Edificio 19, San Martin (1650), Buenos Aires, Argentina. AbstractTopoisomerase-II accumulates at centromeres during prometaphase, where it resolves the DNA catenations that represent the last link between sister chromatids. Previously, using approaches including etoposide-mediated topoisomerase-II cleavage, we mapped centromeric domains in trypanosomes, early branching eukaryotes in which chromosome segregation is poorly understood. Here, we show that in bloodstream form Trypanosoma brucei, RNAi-mediated depletion of topoisomerase-IIα, but not topoisomerase-IIβ, results in the abolition of centromere-localized activity and is lethal. Both phenotypes can be rescued by expression of the corresponding enzyme from T. cruzi. Therefore, processes which govern centromere-specific topoisomerase-II accumulation/activation have been functionally conserved within trypanosomes, despite the long evolutionary separation of these species and differences in centromeric DNA organization. The variable carboxyl terminal region of topoisomerase-II has a major role in regulating biological function. We therefore generated T. brucei lines expressing T. cruzi topoisomerase-II truncated at the carboxyl terminus and examined activity at centromeres after the RNAi-mediated depletion of the endogenous enzyme. A region necessary for nuclear localization was delineated to six residues. In other organisms, sumoylation of topoisomerase-II has been shown to be necessary for regulated chromosome segregation. Evidence that we present here suggests that sumoylation of the T. brucei enzyme is not required for centromere-specific cleavage activity. |
| PMID: 20864447 [PubMed - as supplied by publisher] | |
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| 3. | Ann Trop Med Parasitol. 2010 Sep;104(6):475-83.Antileishmanial activity of an essential oil from the leaves and flowers of Achillea millefolium.Santos AO, Santin AC, Yamaguchi MU, Cortez LE, Ueda-Nakamura T, Dias-Filho BP, Nakamura CV.Programa de Pós-graduação em Microbiologia, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid, PR 445, Km 380, Londrina, Paraná, Brazil. AbstractAn essential oil was recently extracted from the leaves and flowers of yarrow (Achillea millefolium) and tested for in-vitro activity against Leishmania amazonensis and murine macrophages (i.e. the J774G8 cell line). The median inhibitory concentration (IC(50)) against L. amazonensis promastigotes was 7.8 μg/ml whereas the survival of amastigotes of this pathogen, within peritoneal murine macrophages, was halved by treatment with the oil at 6.5 μg/ml. The mean value for the median cytotoxic concentration of the oil, measured against adherent (uninfected) J774G8 macrophages, was 72.0 μg/ml (i.e. 9.2 and 11.0 times higher, respectively, than the IC(50) against the promastigotes and intracellular amastigotes). Scanning electron microscopy revealed that the oil caused morphological changes in the treated parasites, including alterations in their shape and size. In transmission electron microscopy, promastigotes treated with the oil (at the IC(50) of 7.8 μg/ml) showed various ultrastructural alterations, including changes in the flagellar membrane, abnormal membrane structures, rupture of the plasma membrane, atypical vacuoles, myelin-like figures, and vesicles that resembled autophagic vacuoles. |
| PMID: 20863436 [PubMed - in process] | |
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| 4. | Acta Crystallogr D Biol Crystallogr. 2010 Aug;66(Pt 8):934-44. Epub 2010 Jul 14.Crystallographic binding studies with an engineered monomeric variant of triosephosphate isomerase.Salin M, Kapetaniou EG, Vaismaa M, Lajunen M, Casteleijn MG, Neubauer P, Salmon L, Wierenga RK.Department of Biochemistry, PO Box 3000, 90014 University of Oulu, Finland. AbstractCrystallographic binding studies have been carried out to probe the active-site binding properties of a monomeric variant (A-TIM) of triosephosphate isomerase (TIM). These binding studies are part of a structure-based directed-evolution project aimed towards changing the substrate specificity of monomeric TIM and are therefore aimed at finding binders which are substrate-like molecules. A-TIM has a modified more extended binding pocket between loop-7 and loop-8 compared with wild-type TIM. The A-TIM crystals were grown in the presence of citrate, which is bound in the active site of each of the two molecules in the asymmetric unit. In this complex, the active-site loops loop-6 and loop-7 adopt the closed conformation, similar to that observed in liganded wild-type TIM. Extensive crystal-soaking protocols have been developed to flush the bound citrate out of the active-site pocket of both molecules and the crystal structure shows that the unliganded open conformation of the A-TIM active site is the same as in unliganded wild-type TIM. It is also shown that sulfonate compounds corresponding to the transition-state analogue 2-phosphoglycolate bind in the active site, which has a closed conformation. It is also shown that the new binding pocket of A-TIM can bind 3-phosphoglycerate (3PGA; an analogue of a C4-sugar phosphate) and 4-phospho-D-erythronohydroxamic acid (4PEH; an analogue of a C5-sugar phosphate). Therefore, these studies have provided a rationale for starting directed-evolution experiments aimed at generating the catalytic properties of a C5-sugar phosphate isomerase on the A-TIM framework. |
| PMID: 20693693 [PubMed - indexed for MEDLINE] | |
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| 5. | PLoS Negl Trop Dis. 2010 Jun 15;4(6):e711.Clinical outcomes of thirteen patients with acute chagas disease acquired through oral transmission from two urban outbreaks in northeastern Brazil.Bastos CJ, Aras R, Mota G, Reis F, Dias JP, de Jesus RS, Freire MS, de Araújo EG, Prazeres J, Grassi MF.Medicine and Human Health PhD Program, Bahian School of Medicine and Public Health, Bahia, Brazil. AbstractBACKGROUND: Outbreaks of orally transmitted Trypanosoma cruzi continue to be reported in Brazil and are associated with a high mortality rate, mainly due to myocarditis. METHODS: This study is a detailed report on the disease progression of acute Chagas disease in 13 patients who were infected during two micro-outbreaks in two northeastern Brazilian towns. Clinical outcomes as well as EKG and ECHO results are described, both before and after benznidazole treatment. RESULTS: Fever and dyspnea were the most frequent symptoms observed. Other clinical findings included myalgia, periorbital edema, headache and systolic murmur. Two patients died of cardiac failure before receiving benznidazole treatment. EKG and ECHO findings frequently showed a disturbance in ventricular repolarization and pericardial effusion. Ventricular dysfunction (ejection fraction <55%) was present in 27.3% of patients. After treatment, EKG readings normalized in 91.7% of patients. Ventricular repolarization abnormalities persisted in 50% of the patients, while sinus bradycardia was observed in 18%. The systolic ejection fraction normalized in two out of three patients with initially depressed ventricular function, while pericardial effusion disappeared. CONCLUSIONS: Myocarditis is frequently found and potentially severe in patients with acute Chagas disease. Benznidazole treatment may improve clinical symptoms, as well as EKG and ECHO findings. |
| PMID: 20559542 [PubMed - indexed for MEDLINE] | |
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| 6. | Arq Gastroenterol. 2009 Oct-Dec;46(4):249-51.[Chagas' disease: 100 years of discovery and current thought of its discoverer][Article in Portuguese] Garcia SB. Free Article |
| PMID: 20232001 [PubMed - indexed for MEDLINE] | |
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