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Sample records for falciparum serine hydroxymethyltransferase

  1. The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities

    Energy Technology Data Exchange (ETDEWEB)

    Chitnumsub, Penchit; Ittarat, Wanwipa; Jaruwat, Aritsara; Noytanom, Krittikar [National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand); Amornwatcharapong, Watcharee [Mahidol University, Bangkok (Thailand); Pornthanakasem, Wichai [National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand); Chaiyen, Pimchai [Mahidol University, Bangkok (Thailand); Yuthavong, Yongyuth; Leartsakulpanich, Ubolsree [National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

    2014-06-01

    The crystal structure of P. falciparum SHMT revealed snapshots of an intriguing disulfide/sulfhydryl switch controlling the functional activity. Plasmodium falciparum serine hydroxymethyltransferase (PfSHMT), an enzyme in the dTMP synthesis cycle, is an antimalarial target because inhibition of its expression or function has been shown to be lethal to the parasite. As the wild-type enzyme could not be crystallized, protein engineering of residues on the surface was carried out. The surface-engineered mutant PfSHMT-F292E was successfully crystallized and its structure was determined at 3 Å resolution. The PfSHMT-F292E structure is a good representation of PfSHMT as this variant revealed biochemical properties similar to those of the wild type. Although the overall structure of PfSHMT is similar to those of other SHMTs, unique features including the presence of two loops and a distinctive cysteine pair formed by Cys125 and Cys364 in the tetrahydrofolate (THF) substrate binding pocket were identified. These structural characteristics have never been reported in other SHMTs. Biochemical characterization and mutation analysis of these two residues confirm that they act as a disulfide/sulfhydryl switch to regulate the THF-dependent catalytic function of the enzyme. This redox switch is not present in the human enzyme, in which the cysteine pair is absent. The data reported here can be further exploited as a new strategy to specifically disrupt the activity of the parasite enzyme without interfering with the function of the human enzyme.

  2. The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities

    International Nuclear Information System (INIS)

    Chitnumsub, Penchit; Ittarat, Wanwipa; Jaruwat, Aritsara; Noytanom, Krittikar; Amornwatcharapong, Watcharee; Pornthanakasem, Wichai; Chaiyen, Pimchai; Yuthavong, Yongyuth; Leartsakulpanich, Ubolsree

    2014-01-01

    The crystal structure of P. falciparum SHMT revealed snapshots of an intriguing disulfide/sulfhydryl switch controlling the functional activity. Plasmodium falciparum serine hydroxymethyltransferase (PfSHMT), an enzyme in the dTMP synthesis cycle, is an antimalarial target because inhibition of its expression or function has been shown to be lethal to the parasite. As the wild-type enzyme could not be crystallized, protein engineering of residues on the surface was carried out. The surface-engineered mutant PfSHMT-F292E was successfully crystallized and its structure was determined at 3 Å resolution. The PfSHMT-F292E structure is a good representation of PfSHMT as this variant revealed biochemical properties similar to those of the wild type. Although the overall structure of PfSHMT is similar to those of other SHMTs, unique features including the presence of two loops and a distinctive cysteine pair formed by Cys125 and Cys364 in the tetrahydrofolate (THF) substrate binding pocket were identified. These structural characteristics have never been reported in other SHMTs. Biochemical characterization and mutation analysis of these two residues confirm that they act as a disulfide/sulfhydryl switch to regulate the THF-dependent catalytic function of the enzyme. This redox switch is not present in the human enzyme, in which the cysteine pair is absent. The data reported here can be further exploited as a new strategy to specifically disrupt the activity of the parasite enzyme without interfering with the function of the human enzyme

  3. Dynamic subcellular localization of isoforms of the folate pathway enzyme serine hydroxymethyltransferase (SHMT through the erythrocytic cycle of Plasmodium falciparum

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    Mitchell Sarah L

    2010-12-01

    Full Text Available Abstract Background The folate pathway enzyme serine hydroxymethyltransferase (SHMT converts serine to glycine and 5,10-methylenetetrahydrofolate and is essential for the acquisition of one-carbon units for subsequent transfer reactions. 5,10-methylenetetrahydrofolate is used by thymidylate synthase to convert dUMP to dTMP for DNA synthesis. In Plasmodium falciparum an enzymatically functional SHMT (PfSHMTc and a related, apparently inactive isoform (PfSHMTm are found, encoded by different genes. Here, patterns of localization of the two isoforms during the parasite erythrocytic cycle are investigated. Methods Polyclonal antibodies were raised to PfSHMTc and PfSHMTm, and, together with specific markers for the mitochondrion and apicoplast, were employed in quantitative confocal fluorescence microscopy of blood-stage parasites. Results As well as the expected cytoplasmic occupancy of PfSHMTc during all stages, localization into the mitochondrion and apicoplast occurred in a stage-specific manner. Although early trophozoites lacked visible organellar PfSHMTc, a significant percentage of parasites showed such fluorescence during the mid-to-late trophozoite and schizont stages. In the case of the mitochondrion, the majority of parasites in these stages at any given time showed no marked PfSHMTc fluorescence, suggesting that its occupancy of this organelle is of limited duration. PfSHMTm showed a distinctly more pronounced mitochondrial location through most of the erythrocytic cycle and GFP-tagging of its N-terminal region confirmed the predicted presence of a mitochondrial signal sequence. Within the apicoplast, a majority of mitotic schizonts showed a marked concentration of PfSHMTc, whose localization in this organelle was less restricted than for the mitochondrion and persisted from the late trophozoite to the post-mitotic stages. PfSHMTm showed a broadly similar distribution across the cycle, but with a distinctive punctate accumulation towards

  4. Conserved water molecules in bacterial serine hydroxymethyltransferases.

    Science.gov (United States)

    Milano, Teresa; Di Salvo, Martino Luigi; Angelaccio, Sebastiana; Pascarella, Stefano

    2015-10-01

    Water molecules occurring in the interior of protein structures often are endowed with key structural and functional roles. We report the results of a systematic analysis of conserved water molecules in bacterial serine hydroxymethyltransferases (SHMTs). SHMTs are an important group of pyridoxal-5'-phosphate-dependent enzymes that catalyze the reversible conversion of l-serine and tetrahydropteroylglutamate to glycine and 5,10-methylenetetrahydropteroylglutamate. The approach utilized in this study relies on two programs, ProACT2 and WatCH. The first software is able to categorize water molecules in a protein crystallographic structure as buried, positioned in clefts or at the surface. The other program finds, in a set of superposed homologous proteins, water molecules that occur approximately in equivalent position in each of the considered structures. These groups of molecules are referred to as 'clusters' and represent structurally conserved water molecules. Several conserved clusters of buried or cleft water molecules were found in the set of 11 bacterial SHMTs we took into account for this work. The majority of these clusters were not described previously. Possible structural and functional roles for the conserved water molecules are envisaged. This work provides a map of the conserved water molecules helpful for deciphering SHMT mechanism and for rational design of molecular engineering experiments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Inhibitors of plasmodial serine hydroxymethyltransferase (SHMT): cocrystal structures of pyrazolopyrans with potent blood- and liver-stage activities.

    Science.gov (United States)

    Witschel, Matthias C; Rottmann, Matthias; Schwab, Anatol; Leartsakulpanich, Ubolsree; Chitnumsub, Penchit; Seet, Michael; Tonazzi, Sandro; Schwertz, Geoffrey; Stelzer, Frank; Mietzner, Thomas; McNamara, Case; Thater, Frank; Freymond, Céline; Jaruwat, Aritsara; Pinthong, Chatchadaporn; Riangrungroj, Pinpunya; Oufir, Mouhssin; Hamburger, Matthias; Mäser, Pascal; Sanz-Alonso, Laura M; Charman, Susan; Wittlin, Sergio; Yuthavong, Yongyuth; Chaiyen, Pimchai; Diederich, François

    2015-04-09

    Several of the enzymes related to the folate cycle are well-known for their role as clinically validated antimalarial targets. Nevertheless for serine hydroxymethyltransferase (SHMT), one of the key enzymes of this cycle, efficient inhibitors have not been described so far. On the basis of plant SHMT inhibitors from an herbicide optimization program, highly potent inhibitors of Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) SHMT with a pyrazolopyran core structure were identified. Cocrystal structures of potent inhibitors with PvSHMT were solved at 2.6 Å resolution. These ligands showed activity (IC50/EC50 values) in the nanomolar range against purified PfSHMT, blood-stage Pf, and liver-stage P. berghei (Pb) cells and a high selectivity when assayed against mammalian cell lines. Pharmacokinetic limitations are the most plausible explanation for lack of significant activity of the inhibitors in the in vivo Pb mouse malaria model.

  6. Differential 3-bromopyruvate inhibition of cytosolic and mitochondrial human serine hydroxymethyltransferase isoforms, key enzymes in cancer metabolic reprogramming.

    Science.gov (United States)

    Paiardini, Alessandro; Tramonti, Angela; Schirch, Doug; Guiducci, Giulia; di Salvo, Martino Luigi; Fiascarelli, Alessio; Giorgi, Alessandra; Maras, Bruno; Cutruzzolà, Francesca; Contestabile, Roberto

    2016-11-01

    The cytosolic and mitochondrial isoforms of serine hydroxymethyltransferase (SHMT1 and SHMT2, respectively) are well-recognized targets of cancer research, since their activity is critical for purine and pyrimidine biosynthesis and because of their prominent role in the metabolic reprogramming of cancer cells. Here we show that 3-bromopyruvate (3BP), a potent novel anti-tumour agent believed to function primarily by blocking energy metabolism, differentially inactivates human SHMT1 and SHMT2. SHMT1 is completely inhibited by 3BP, whereas SHMT2 retains a significant fraction of activity. Site directed mutagenesis experiments on SHMT1 demonstrate that selective inhibition relies on the presence of a cysteine residue at the active site of SHMT1 (Cys204) that is absent in SHMT2. Our results show that 3BP binds to SHMT1 active site, forming an enzyme-3BP complex, before reacting with Cys204. The physiological substrate l-serine is still able to bind at the active site of the inhibited enzyme, although catalysis does not occur. Modelling studies suggest that alkylation of Cys204 prevents a productive binding of l-serine, hampering interaction between substrate and Arg402. Conversely, the partial inactivation of SHMT2 takes place without the formation of a 3BP-enzyme complex. The introduction of a cysteine residue in the active site of SHMT2 by site directed mutagenesis (A206C mutation), at a location corresponding to that of Cys204 in SHMT1, yields an enzyme that forms a 3BP-enzyme complex and is completely inactivated. This work sets the basis for the development of selective SHMT1 inhibitors that target Cys204, starting from the structure and reactivity of 3BP. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. [Correlations between serine hydroxymethyltransferase1 C1420T polymorphisms and susceptibilities to esophageal squamous cell carcinoma and gastric cardiac adenocarcinoma].

    Science.gov (United States)

    Wang, Yi-Min; Guo, Wei; Zhang, Xiu-Feng; Li, Yan; Wang, Na; Ge, Hui; Wei, Li-Zhen; Wen, Deng-Gui; Zhang, Jian-Hui

    2006-03-01

    Serine hydroxymethyltransferase (SHMT), a key enzyme in the folate metabolism, affects gene methylation and DNA synthesis through providing one-carbon units for purine, thymidylate, and methionine. It is closely related to the development and progression of tumors. This study was to investigate the correlations between SHMT1 C1420T single nucleotide polymorphisms (SNP) and susceptibilities to esophageal squamous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA). SHMT1 C1420T SNP was genotyped by polymerase chain reaction-confronting two-pair primers (PCR-CTPP) analysis in 584 ESCC patients, 467 GCA patients, and 540 healthy controls. The correlations between SHMT1 C1420T SNP polymorphisms and susceptibilities to ESCC and GCA were analyzed with Logistic regression model. Family history of upper gastrointestinal cancer (UGIC) significantly enhanced the risk of developing ESCC and GCA [the age, gender, smoking status, and family history of UGIC adjusted odds ratio (OR)=2.89, 95% confident interval (CI)=2.23-3.73; OR =1.68, 95% CI=1.28-2.23]. The frequency of 1420C/T genotype was significantly lower in ESCC and GCA patients than in healthy controls (12.0% vs. 16.5%, Pnon-smokers, with adjusted OR of 0.54 (95% CI=0.33-0.90) for ESCC and 0.56 (95% CI=0.33-0.95) for GCA. In addition, C/T genotype significantly reduced susceptibility to GCA among individuals with or without UGIC history, with adjusted OR of 0.46 (95%CI=0.24-0.90) and 0.62 (95% CI=0.38-0.99) respectively, and reduced susceptibility to ESCC only among individuals with UGIC history, with adjusted OR of 0.51 (95% CI=0.29-0.89). SHMT1 1420C/T genotype could significantly reduce susceptibilities to ESCC and GCA among individuals from high risk areas in Hebei Province of China.

  8. Characterization of serine hydroxymethyltransferase GlyA as a potential source of D-alanine in Chlamydia pneumoniae.

    Science.gov (United States)

    De Benedetti, Stefania; Bühl, Henrike; Gaballah, Ahmed; Klöckner, Anna; Otten, Christian; Schneider, Tanja; Sahl, Hans-Georg; Henrichfreise, Beate

    2014-01-01

    For intracellular Chlamydiaceae, there is no need to withstand osmotic challenges, and a functional cell wall has not been detected in these pathogens so far. Nevertheless, penicillin inhibits cell division in Chlamydiaceae resulting in enlarged aberrant bodies, a phenomenon known as chlamydial anomaly. D-alanine is a unique and essential component in the biosynthesis of bacterial cell walls. In free-living bacteria like Escherichia coli, penicillin-binding proteins such as monofunctional transpeptidases PBP2 and PBP3, the putative targets of penicillin in Chlamydiaceae, cross-link adjacent peptidoglycan strands via meso-diaminopimelic acid and D-Ala-D-Ala moieties of pentapeptide side chains. In the absence of genes coding for alanine racemase Alr and DadX homologs, the source of D-Ala and thus the presence of substrates for PBP2 and PBP3 activity in Chlamydiaceae has puzzled researchers for years. Interestingly, Chlamydiaceae genomes encode GlyA, a serine hydroxymethyltransferase that has been shown to exhibit slow racemization of D- and L-alanine as a side reaction in E. coli. We show that GlyA from Chlamydia pneumoniae can serve as a source of D-Ala. GlyA partially reversed the D-Ala auxotrophic phenotype of an E. coli racemase double mutant. Moreover, purified chlamydial GlyA had racemase activity on L-Ala in vitro and was inhibited by D-cycloserine, identifying GlyA, besides D-Ala ligase MurC/Ddl, as an additional target of this competitive inhibitor in Chlamydiaceae. Proof of D-Ala biosynthesis in Chlamydiaceae helps to clarify the structure of cell wall precursor lipid II and the role of chlamydial penicillin-binding proteins in the development of non-dividing aberrant chlamydial bodies and persistence in the presence of penicillin.

  9. Characterization of serine hydroxymethyltransferase GlyA as a potential source of D-alanine in Chlamydia pneumoniae

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    Stefania eDe Benedetti

    2014-02-01

    Full Text Available For intracellular Chlamydiaceae, there is no need to withstand osmotic challenges, and a functional cell wall has not been detected in these pathogens so far. Nevertheless, penicillin inhibits cell division in Chlamydiaceae resulting in enlarged aberrant bodies, a phenomenon known as chlamydial anomaly.D-alanine is a unique and essential component in the biosynthesis of bacterial cell walls. In free-living bacteria like Escherichia coli, penicillin-binding proteins such as monofunctional transpeptidases PBP2 and PBP3, the putative targets of penicillin in Chlamydiaceae, cross-link adjacent peptidoglycan strands via meso-diaminopimelic acid and D-Ala-D-Ala moieties of pentapeptide side chains. In the absence of genes coding for alanine racemase Alr and DadX homologs, the source of D-Ala and thus the presence of substrates for PBP2 and PBP3 activity in Chlamydiaceae has puzzled researchers for years. Interestingly, Chlamydiaceae genomes encode GlyA, a serine hydroxymethyltransferase that has been shown to exhibit slow racemization of D- and L- alanine as a side reaction in E. coli. We show that GlyA from Chlamydia pneumoniae can serve as a source of D-Ala. GlyA partially reversed the D-Ala auxotrophic phenotype of an E. coli racemase double mutant. Moreover, purified chlamydial GlyA had racemase activity on L-Ala in vitro and was inhibited by D-cycloserine, identifying GlyA, besides D-Ala ligase MurC/Ddl, as an additional target of this competitive inhibitor in Chlamydiaceae. Proof of D-Ala biosynthesis in Chlamydiaceae helps to clarify the structure of cell wall precursor lipid II and the role of chlamydial penicillin-binding proteins in the development of non-dividing aberrant chlamydial bodies and persistence in the presence of penicillin.

  10. Antibodies reactive to Plasmodium falciparum serine repeat antigen in children with Burkitt lymphoma from Ghana.

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    Guech-Ongey, Mercy; Yagi, Masanori; Palacpac, Nirianne Marie Q; Emmanuel, Benjamin; Talisuna, Ambrose O; Bhatia, Kishor; Stefan, D Cristina; Biggar, Robert J; Nkrumah, Francis; Neequaye, Janet; Tougan, Takahiro; Horii, Toshihiro; Mbulaiteye, Sam M

    2012-04-15

    The role of protective immunity to Plasmodium falciparum (Pf) malaria in Burkitt lymphoma (BL) is unknown. We investigated the association between BL and antibodies reactive to SE36 antigen, a recombinant protein based on P. falciparum serine repeat antigen 5 gene, targeted by protective malaria immune responses. Cases were children (0-14 years) enrolled at the Korle-Bu Teaching Hospital, Accra, Ghana, during 1965-1994 with BL confirmed by histology or cytology (92% of cases). Controls were apparently healthy children enrolled contemporaneous to the cases from the nearest neighbor house to the case house and were age,- sex-frequency-matched to the cases. Anti-SE36 IgG antibodies were measured using enzyme-linked absorbent immunoassays (ELISAs). SE36 titers were estimated by extrapolating ELISA optical density readings to a standard fitting curve. Anti-SE36 titers were log-transformed for analysis. Odds ratios (ORs) and two-sided 95% confidence intervals (95% CIs) were estimated using unconditional logistic regression. The mean log endpoint dilution titers were 0.63 logs lower in cases than in controls (8.26 [SD 1.68] vs. 8.89 [SD 1.75], Student's t-test, p = 0.019). Lower titers were observed in cases than controls aged 0-4 years (p = 0.05) and in those aged 5-14 years (p = 0.06). Low and medium tertiles of anti-SE36 IgG antibodies were associated with increased OR for BL ([OR 1.67, 95% CI 1.21-2.31] and [OR 1.33, 95% CI 0.96-1.86], respectively, p(trend) = 0.002) in analyses adjusting for age, sex, calendar period and test plate. Our findings suggest that compared to similarly aged children enrolled from the same community, children with BL in Ghana have lower antibodies to SE36 antigen. Copyright © 2011 UICC.

  11. A novel tetratricopeptide repeat (TPR containing PP5 serine/threonine protein phosphatase in the malaria parasite, Plasmodium falciparum

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    Adams Brian

    2001-11-01

    Full Text Available Abstract Background The malarial parasite, Plasmodium falciparum (Pf, is responsible for nearly 2 million deaths worldwide. However, the mechanisms of cellular signaling in the parasite remain largely unknown. Recent discovery of a few protein kinases and phosphatases point to a thriving reversible phosphorylation system in the parasite, although their function and regulation need to be determined. Results We provide biochemical and sequence evidence for a protein serine/threonine phosphatase type PP5 in Plasmodium falciparum, and named it PfPP5. The 594-amino acid polypeptide was encoded by a 1785 nucleotide long intronless gene in the parasite. The recombinant protein, expressed in bacteria, was indistinguishable from native PfPP5. Sequencing comparison indicated that the extra-long N-terminus of PfPP5 outside the catalytic core contained four tetratricopeptide repeats (TPRs, compared to three such repeats in other PP5 phosphatases. The PfPP5 N-terminus was required for stimulation of the phosphatase activity by polyunsaturated fatty acids. Co-immunoprecipitation demonstrated an interaction between native PfPP5 and Pf heat shock protein 90 (hsp90. PfPP5 was expressed in all the asexual erythrocytic stages of the parasite, and was moderately sensitive to okadaic acid. Conclusions This is the first example of a TPR-domain protein in the Apicomplexa family of parasites. Since TPR domains play important roles in protein-protein interaction, especially relevant to the regulation of PP5 phosphatases, PfPP5 is destined to have a definitive role in parasitic growth and signaling pathways. This is exemplified by the interaction between PfPP5 and the cognate chaperone hsp90.

  12. Reprogramming One-Carbon Metabolic Pathways To Decouple l-Serine Catabolism from Cell Growth in Corynebacterium glutamicum.

    Science.gov (United States)

    Zhang, Yun; Shang, Xiuling; Lai, Shujuan; Zhang, Yu; Hu, Qitiao; Chai, Xin; Wang, Bo; Liu, Shuwen; Wen, Tingyi

    2018-02-16

    l-Serine, the principal one-carbon source for DNA biosynthesis, is difficult for microorganisms to accumulate due to the coupling of l-serine catabolism and microbial growth. Here, we reprogrammed the one-carbon unit metabolic pathways in Corynebacterium glutamicum to decouple l-serine catabolism from cell growth. In silico model-based simulation showed a negative influence on glyA-encoding serine hydroxymethyltransferase flux with l-serine productivity. Attenuation of glyA transcription resulted in increased l-serine accumulation, and a decrease in purine pools, poor growth and longer cell shapes. The gcvTHP-encoded glycine cleavage (Gcv) system from Escherichia coli was introduced into C. glutamicum, allowing glycine-derived 13 CH 2 to be assimilated into intracellular purine synthesis, which resulted in an increased amount of one-carbon units. Gcv introduction not only restored cell viability and morphology but also increased l-serine accumulation. Moreover, comparative proteomic analysis indicated that abundance changes of the enzymes involved in one-carbon unit cycles might be responsible for maintaining one-carbon unit homeostasis. Reprogramming of the one-carbon metabolic pathways allowed cells to reach a comparable growth rate to accumulate 13.21 g/L l-serine by fed-batch fermentation in minimal medium. This novel strategy provides new insights into the regulation of cellular properties and essential metabolite accumulation by introducing an extrinsic pathway.

  13. Characterisation and expression of a PP1 serine/threonine protein phosphatase (PfPP1 from the malaria parasite, Plasmodium falciparum: demonstration of its essential role using RNA interference

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    Musiyenko Alla

    2002-04-01

    Full Text Available Abstract Background Reversible protein phosphorylation is relatively unexplored in the intracellular protozoa of the Apicomplexa family that includes the genus Plasmodium, to which belong the causative agents of malaria. Members of the PP1 family represent the most highly conserved protein phosphatase sequences in phylogeny and play essential regulatory roles in various cellular pathways. Previous evidence suggested a PP1-like activity in Plasmodium falciparum, not yet identified at the molecular level. Results We have identified a PP1 catalytic subunit from P. falciparum and named it PfPP1. The predicted primary structure of the 304-amino acid long protein was highly similar to PP1 sequences of other species, and showed conservation of all the signature motifs. The purified recombinant protein exhibited potent phosphatase activity in vitro. Its sensitivity to specific phosphatase inhibitors was characteristic of the PP1 class. The authenticity of the PfPP1 cDNA was further confirmed by mutational analysis of strategic amino acid residues important in catalysis. The protein was expressed in all erythrocytic stages of the parasite. Abrogation of PP1 expression by synthetic short interfering RNA (siRNA led to inhibition of parasite DNA synthesis. Conclusions The high sequence similarity of PfPP1 with other PP1 members suggests conservation of function. Phenotypic gene knockdown studies using siRNA confirmed its essential role in the parasite. Detailed studies of PfPP1 and its regulation may unravel the role of reversible protein phosphorylation in the signalling pathways of the parasite, including glucose metabolism and parasitic cell division. The use of siRNA could be an important tool in the functional analysis of Apicomplexan genes.

  14. Serine biosynthesis and transport defects.

    Science.gov (United States)

    El-Hattab, Ayman W

    2016-07-01

    l-serine is a non-essential amino acid that is biosynthesized via the enzymes phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Besides its role in protein synthesis, l-serine is a potent neurotrophic factor and a precursor of a number of essential compounds including phosphatidylserine, sphingomyelin, glycine, and d-serine. Serine biosynthesis defects result from impairments of PGDH, PSAT, or PSP leading to systemic serine deficiency. Serine biosynthesis defects present in a broad phenotypic spectrum that includes, at the severe end, Neu-Laxova syndrome, a lethal multiple congenital anomaly disease, intermediately, infantile serine biosynthesis defects with severe neurological manifestations and growth deficiency, and at the mild end, the childhood disease with intellectual disability. A serine transport defect resulting from deficiency of the ASCT1, the main transporter for serine in the central nervous system, has been recently described in children with neurological manifestations that overlap with those observed in serine biosynthesis defects. l-serine therapy may be beneficial in preventing or ameliorating symptoms in serine biosynthesis and transport defects, if started before neurological damage occurs. Herein, we review serine metabolism and transport, the clinical, biochemical, and molecular aspects of serine biosynthesis and transport defects, the mechanisms of these diseases, and the potential role of serine therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Vitamin B6-Dependent Enzymes in the Human Malaria Parasite Plasmodium falciparum: A Druggable Target?

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    Thales Kronenberger

    2014-01-01

    Full Text Available Malaria is a deadly infectious disease which affects millions of people each year in tropical regions. There is no effective vaccine available and the treatment is based on drugs which are currently facing an emergence of drug resistance and in this sense the search for new drug targets is indispensable. It is well established that vitamin biosynthetic pathways, such as the vitamin B6 de novo synthesis present in Plasmodium, are excellent drug targets. The active form of vitamin B6, pyridoxal 5-phosphate, is, besides its antioxidative properties, a cofactor for a variety of essential enzymes present in the malaria parasite which includes the ornithine decarboxylase (ODC, synthesis of polyamines, the aspartate aminotransferase (AspAT, involved in the protein biosynthesis, and the serine hydroxymethyltransferase (SHMT, a key enzyme within the folate metabolism.

  16. Phosphorylation of mouse serine racemase regulates D-serine synthesis

    DEFF Research Database (Denmark)

    Foltyn, Veronika N; Zehl, Martin; Dikopoltsev, Elena

    2010-01-01

    Serine racemase (SR) catalyses the synthesis of the transmitter/neuromodulator D-serine, which plays a major role in synaptic plasticity and N-methyl D-aspartate receptor neurotoxicity. We now report that SR is phosphorylated at Thr71 and Thr227 as revealed by mass spectrometric analysis and in v...... with a phosphorylation-deficient SR mutant indicate that Thr71 phosphorylation increases SR activity, suggesting a novel mechanism for regulating D-serine production....

  17. Experimental and metabolic modeling evidence for a folate-cleaving side-activity of ketopantoate hydroxymethyltransferase (PanB

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    Jennifer eThiaville

    2016-03-01

    Full Text Available Tetrahydrofolate (THF and its one-carbon derivatives, collectively termed folates, are essential cofact¬ors, but are inherently unstable. While it is clear that chemical oxidation can cleave folates or damage their pterin precursors, very little is known about enzymatic damage to these molec-ules or about whether the folate biosynthesis pathway responds adaptively to damage to its end-pro¬¬ducts. The presence of a duplication of the gene encoding the folate biosynthesis enzyme 6-hydr¬oxymethyl-7,8-dihydropterin pyrophosphokinase (FolK in many sequenced bacterial gen-omes combined with a strong chromosomal clustering of the folK gene with panB, encoding the 5,10-methylene-THF-dependent enzyme ketopantoate hydroxymethyltransferase, led us to infer that PanB has a side activity that cleaves 5,10-methylene-THF, yielding a pterin product that is recycled by FolK. Genetic and metabolic analyses of Escherichia coli strains showed that over-expression of PanB leads to accumulation of the likely folate cleavage product 6-hydroxy¬methyl-pterin and other pterins in cells and medium, and – unexpectedly – to a 46% increase in total fol-ate content. In silico modeling of the folate bio¬syn¬thesis pathway showed that these observations are consistent with the in vivo cleavage of 5,10-methylene-THF by a side-activity of PanB, with FolK-mediated recycling of the pterin cleavage product, and with regulation of folate biosynth-esis by folates or their damage products.

  18. Plasmodium falciparum malaria

    African Journals Online (AJOL)

    Durrheim, Karen Barnes. Objectives. To assess the therapeutic efficacy of sulfadoxine- pyrimethamine (SP) after 5 years of use as first-line treatment of uncomplicated Plasmodium falciparum malaria, and thus guide the selection of artemisinin-based combination therapy in Mpumalanga, South Africa. Design. An open-label ...

  19. An Epithelial Serine Protease, AgESP, Is Required for Plasmodium Invasion in the Mosquito Anopheles gambiae

    Czech Academy of Sciences Publication Activity Database

    Rodrigues, J.; Oliveira, G. A.; Kotsyfakis, Michalis; Dixit, R.; Molina-Cruz, A.; Jochim, R.; Barillas-Mury, C.

    2012-01-01

    Roč. 7, č. 4 (2012), e35210 E-ISSN 1932-6203 Institutional support: RVO:60077344 Keywords : malaria * mosquito * serine protease * sporozoites * ookinetes * gene silencing * midgut * salivary glands * Plasmodium falciparum * Anopheles gambiae Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.730, year: 2012 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035210

  20. Plasmodium falciparum avoids change in erythrocytic surface expression of phagocytosis markers during inhibition of nitric oxide synthase activity

    DEFF Research Database (Denmark)

    Hempel, Casper; Kohnke, Hannes; Maretty, Lasse

    2014-01-01

    Nitric oxide (NO) accumulates in Plasmodium falciparum-infected erythrocytes. It may be produced by a parasite NO synthase (NOS) or by nitrate reduction. The parasite's benefit of NO accumulation is not understood. We investigated if inhibiting the P. falciparum NOS with specific and unspecific NOS...... increased the fraction of phosphatidyl serine exposing cells significantly. The infection did not change the level of expression of neither total CD47 nor its oxidized form. Unrelated to NOS inhibition, incubation with caveolin-1 scaffolding domain peptide lead to a decrease in oxidized CD47. In conclusion...

  1. Premunition in Plasmodium falciparum malaria

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-08

    Mar 8, 2010 ... antigenic polymorphism, shedding of parts of parasite proteins, cross-reactive epitopes of antigens of ... Due to the lack of HLA molecules on the surface of the .... Susceptibility and death rates in P. falciparum malaria are.

  2. Use of chloroquine in uncomplicated falciparum malaria ...

    African Journals Online (AJOL)

    Use of chloroquine in uncomplicated falciparum malaria chemotherapy: The past, the present and the future. ... regions. It was initially highly effective against the four Plasmodium species (P. falciparum, P. malaria, P. ovale and P. vivax) infecting human. It is also effective against gametocytes except those of P. falciparum.

  3. Glycine serine interconversion in the rooster

    International Nuclear Information System (INIS)

    Sugahara, Michihiro; Kandatsu, Makoto

    1976-01-01

    Serine was isolated by the column chromatography from the hydrolyzates of proteins of the serum, the liver and the pectoral muscle which were obtained from the roosters fed a diet containing 2- 14 C glycine for 16 - 17 days. The carbon chain of serine was cut off by treating with sodium periodate. The specific activity of each carbon (as barium carbonate) was estimated. Carboxyl carbon had little radioactivity. The specific activity of hydroxymethyl carbon was 10 - 19% of that of methylene carbon. Glycine isolated from the same hydrolyzates was degraded by ninhydrin oxidation. Formaldehyde produced from 2-C was oxidized to carbon dioxide by treating with mercuric chloride. Carboxyl carbon had little radioactivity. The specific activities of 2-C of glycine and 2-C of serine in the same tissue protein were compared. The ratio of serine 2-C/glycine 2-C was between 0.7 - 1.5. These results seem to indicate that glycine directly converts to serine in the rooster. The quantitative significance of the pathways of glycine (serine) biosynthesis is discussed. (auth.)

  4. D-serine increases adult hippocampal neurogenesis

    Directory of Open Access Journals (Sweden)

    Sebastien eSultan

    2013-08-01

    Full Text Available Adult hippocampal neurogenesis results in the continuous formation of new neurons and is a process of brain plasticity involved in learning and memory. The neurogenic niche regulates the stem cell proliferation and the differentiation and survival of new neurons and a major contributor to the neurogenic niche are astrocytes. Among the molecules secreted by astrocytes, D-serine is an important gliotransmitter and is a co-agonist of the glutamate, N-methyl-D-aspartate (NMDA receptor. D-serine has been shown to enhance the proliferation of neural stem cells in vitro, but its effect on adult neurogenesis in vivo is unknown. Here, we tested the effect of exogenous administration of D-serine on adult neurogenesis in the mouse dentate gyrus. We found that 1 week of treatment with D-serine increased cell proliferation in vivo and in vitro and increased the density of neural stem cells and transit amplifying progenitors. Furthermore, D-serine increased the survival of newborn neurons. Together, these results indicate that D-serine treatment resulted in the improvement of several steps of adult neurogenesis in vivo.

  5. Serine protease inhibitors of parasitic helminths.

    Science.gov (United States)

    Molehin, Adebayo J; Gobert, Geoffrey N; McManus, Donald P

    2012-05-01

    Serine protease inhibitors (serpins) are a superfamily of structurally conserved proteins that inhibit serine proteases and play key physiological roles in numerous biological systems such as blood coagulation, complement activation and inflammation. A number of serpins have now been identified in parasitic helminths with putative involvement in immune regulation and in parasite survival through interference with the host immune response. This review describes the serpins and smapins (small serine protease inhibitors) that have been identified in Ascaris spp., Brugia malayi, Ancylostoma caninum Onchocerca volvulus, Haemonchus contortus, Trichinella spiralis, Trichostrongylus vitrinus, Anisakis simplex, Trichuris suis, Schistosoma spp., Clonorchis sinensis, Paragonimus westermani and Echinococcus spp. and discusses their possible biological functions, including roles in host-parasite interplay and their evolutionary relationships.

  6. Serine:glyoxylate aminotransferase mutant of barley

    International Nuclear Information System (INIS)

    Blackwell, R.; Murray, A.; Joy, K.; Lea, P.

    1987-01-01

    A photorespiratory mutant of barley (LaPr 85/84), deficient in both of the major peaks of serine:glyoxylate aminotransferase activity detected in the wild type, also lacks serine:pyruvate and asparagine:glyoxylate aminotransferase activities. Genetic analysis of the mutation demonstrated that these three activities are all carried on the same enzyme. The mutant, when placed in air, accumulated a large pool of serine, showed the expected rate (50%) of ammonia release during photorespiration but produced CO 2 at twice the wild type rate when it was fed [ 14 C] glyoxylate. Compared with the wild type, LaPr 85/84 exhibited abnormal transient changes in chlorophyll a fluorescence when the CO 2 concentration of the air was altered, indicating that the rates of the fluorescence quenching mechanisms were affected in vivo by the lack of this enzyme

  7. The Plasmodium serine-type SERA proteases display distinct expression patterns and non-essential in vivo roles during life cycle progression of the malaria parasite.

    Science.gov (United States)

    Putrianti, Elyzana D; Schmidt-Christensen, Anja; Arnold, Iris; Heussler, Volker T; Matuschewski, Kai; Silvie, Olivier

    2010-06-01

    Parasite proteases play key roles in several fundamental steps of the Plasmodium life cycle, including haemoglobin degradation, host cell invasion and parasite egress. Plasmodium exit from infected host cells appears to be mediated by a class of papain-like cysteine proteases called 'serine repeat antigens' (SERAs). A SERA subfamily, represented by Plasmodium falciparum SERA5, contains an atypical active site serine residue instead of a catalytic cysteine. Members of this SERAser subfamily are abundantly expressed in asexual blood stages, rendering them attractive drug and vaccine targets. In this study, we show by antibody localization and in vivo fluorescent tagging with the red fluorescent protein mCherry that the two P. berghei serine-type family members, PbSERA1 and PbSERA2, display differential expression towards the final stages of merozoite formation. Via targeted gene replacement, we generated single and double gene knockouts of the P. berghei SERAser genes. These loss-of-function lines progressed normally through the parasite life cycle, suggesting a specialized, non-vital role for serine-type SERAs in vivo. Parasites lacking PbSERAser showed increased expression of the cysteine-type PbSERA3. Compensatory mechanisms between distinct SERA subfamilies may thus explain the absence of phenotypical defect in SERAser disruptants, and challenge the suitability to develop potent antimalarial drugs based on specific inhibitors of Plasmodium serine-type SERAs.

  8. Increased tolerance towards serine obtained by adaptive laboratory evolution

    DEFF Research Database (Denmark)

    Mundhada, Hemanshu; Seoane, Jose Miguel; Koza, Anna

    2014-01-01

    The amino acid serine has previously been identified as one of the top 30 candidates of value added chemicals, making the production of serine from glucose attractive. Production of serine have previously been attempted in E. coli and C. glutamicum, however, titers sufficient for commercial...... by glyA), the conversion of serine to pyruvate (encoded by sdaA, sdaB and tdcG) was also deleted. As expected, the resulting strain turned out to be susceptible to even low concentrations of serine in the media. In order to improve the tolerance of the strain towards serine, adaptive laboratory evolution....... During the evolution experiment, the serine tolerance was increased substantially. Genome re-sequencing was subsequently used to analyze the genotype of a number of selected strains. These results reveal insights towards the adaptation process as well as the mechanism of serine tolerance....

  9. Method for the production of l-serine using genetically engineered microorganisms deficient in serine degradation pathways

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention generally relates to the microbiological industry, and specifically to the production of L-serine using genetically modified bacteria. The present invention provides genetically modified microorganisms, such as bacteria, wherein the expression of genes encoding for enzymes...... concentrations of serine. The present invention also provides methods for the production of L-serine or L-serine derivative using such genetically modified microorganisms....

  10. Plasmodium falciparum: attenuation by irradiation

    International Nuclear Information System (INIS)

    Waki, S.; Yonome, I.; Suzuki, M.

    1983-01-01

    The effect of irradiation on the in vitro growth of Plasmodium falciparum was investigated. The cultured malarial parasites at selected stages of development were exposed to gamma rays and the sensitivity of each stage was determined. The stages most sensitive to irradiation were the ring forms and the early trophozoites; late trophozoites were relatively insensitive. The greatest resistance was shown when parasites were irradiated at a time of transition from the late trophozoite and schizont stages to young ring forms. The characteristics of radiosensitive variation in the parasite cycle resembled that of mammalian cells. Growth curves of parasites exposed to doses of irradiation upto 150 gray had the same slope as nonirradiated controls but parasites which were exposed to 200 gray exhibited a growth curve which was less steep than that for parasites in other groups. Less than 10 organisms survived from the 10(6) parasites exposed to this high dose of irradiation; the possibility exists of obtaining radiation-attenuated P. falciparum

  11. Combinatorial gene regulation in Plasmodium falciparum.

    NARCIS (Netherlands)

    Noort, V. van; Huynen, M.A.

    2006-01-01

    The malaria parasite Plasmodium falciparum has a complicated life cycle with large variations in its gene expression pattern, but it contains relatively few specific transcriptional regulators. To elucidate this paradox, we identified regulatory sequences, using an approach that integrates the

  12. Serine proteinases and their inhibitors in fertilization

    Czech Academy of Sciences Publication Activity Database

    Jonáková, Věra; Jelínková-Slavíčková, Petra

    2004-01-01

    Roč. 8, 3,4 (2004), s. 108-110 ISSN 1211-8869. [Central European Conference on Human Tumor Markers /5./. Praha, 01.10.2004-03.10.2004] R&D Projects: GA ČR GA303/02/0433; GA ČR GP303/02/P069; GA ČR GP303/04/P070; GA MZd NJ7463 Institutional research plan: CEZ:AV0Z5052915 Keywords : serine proteinase * proteinase inhibitors * fertilization Subject RIV: CE - Biochemistry

  13. A cytotoxic serine proteinase isolated from mouse submandibular gland.

    Science.gov (United States)

    Shimamura, T; Nagumo, N; Ikigai, H; Murakami, K; Okubo, S; Toda, M; Ohnishi, R; Tomita, M

    1989-08-01

    We have isolated a novel cytotoxic factor from the submandibular glands of male BALB/c mice by Sephadex G-50 gel filtration chromatography and reverse-phase HPLC. The cytotoxic factor is a serine proteinase, which belongs to the mouse glandular kallikrein (mGK) family, with an Mr of approximately 27,000. The purified serine proteinase showed cytotoxic activity against mouse thymocytes in a dose-dependent manner, and a serine proteinase inhibitor, diisopropyl fluorophosphate, blocked its cytotoxic activity.

  14. Squash inhibitor family of serine proteinases

    International Nuclear Information System (INIS)

    Otlewski, J.; Krowarsch, D.

    1996-01-01

    Squash inhibitors of serine proteinases form an uniform family of small proteins. They are built of 27-33 amino-acid residues and cross-linked with three disulfide bridges. The reactive site peptide bond (P1-P1') is between residue 5 (Lys, Arg or Leu) and 6 (always Ile). High resolution X-ray structures are available for two squash inhibitors complexed with trypsin. NMR solution structures have also been determined for free inhibitors. The major structural motif is a distorted, triple-stranded antiparallel beta-sheet. A similar folding motif has been recently found in a number of proteins, including: conotoxins from fish-hunting snails, carboxypeptidase inhibitor from potato, kalata B1 polypeptide, and in some growth factors (e.g. nerve growth factor, transforming growth factor β2, platelet-derived growth factor). Squash inhibitors are highly stable and rigid proteins. They inhibit a number of serine proteinases: trypsin, plasmin, kallikrein, blood clotting factors: X a and XII a , cathepsin G. The inhibition spectrum can be much broadened if specific amino-acid substitutions are introduced, especially at residues which contact proteinase. Squash inhibitors inhibit proteinases via the standard mechanism. According to the mechanism, inhibitors are substrates which exhibit at neutral pH a high k cat /K m index for hydrolysis and resynthesis of the reactive site, and a low value of the hydrolysis constant. (author)

  15. Understanding serine proteases implications on Leishmania spp lifecycle.

    Science.gov (United States)

    Alves, Carlos Roberto; Souza, Raquel Santos de; Charret, Karen Dos Santos; Côrtes, Luzia Monteiro de Castro; Sá-Silva, Matheus Pereira de; Barral-Veloso, Laura; Oliveira, Luiz Filipe Gonçalves; da Silva, Franklin Souza

    2018-01-01

    Serine proteases have significant functions over a broad range of relevant biological processes to the Leishmania spp lifecycle. Data gathered here present an update on the Leishmania spp serine proteases and the status of these enzymes as part of the parasite degradome. The serine protease genes (n = 26 to 28) in Leishmania spp, which encode proteins with a wide range of molecular masses (35 kDa-115 kDa), are described along with their degrees of chromosomal and allelic synteny. Amid 17 putative Leishmania spp serine proteases, only ∼18% were experimentally demonstrated, as: signal peptidases that remove the signal peptide from secretory pre-proteins, maturases of other proteins and with metacaspase-like activity. These enzymes include those of clans SB, SC and SF. Classical inhibitors of serine proteases are used as tools for the characterization and investigation of Leishmania spp. Endogenous serine protease inhibitors, which are ecotin-like, can act modulating host actions. However, crude or synthetic based-natural serine protease inhibitors, such as potato tuber extract, Stichodactyla helianthus protease inhibitor I, fukugetin and epoxy-α-lapachone act on parasitic serine proteases and are promising leishmanicidal agents. The functional interrelationship between serine proteases and other Leishmania spp proteins demonstrate essential functions of these enzymes in parasite physiology and therefore their value as targets for leishmaniasis treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Neonatal disruption of serine racemase causes schizophrenia-like behavioral abnormalities in adulthood: clinical rescue by d-serine.

    Directory of Open Access Journals (Sweden)

    Hiroko Hagiwara

    Full Text Available D-Serine, an endogenous co-agonist of the N-methyl-D-aspartate (NMDA receptor, is synthesized from L-serine by serine racemase (SRR. Given the role of D-serine in both neurodevelopment and the pathophysiology of schizophrenia, we examined whether neonatal disruption of D-serine synthesis by SRR inhibition could induce behavioral abnormalities relevant to schizophrenia, in later life.Neonatal mice (7-9 days were injected with vehicle or phenazine methosulfate (Met-Phen: 3 mg/kg/day, an SRR inhibitor. Behavioral evaluations, such as spontaneous locomotion, novel object recognition test (NORT, and prepulse inhibition (PPI were performed at juvenile (5-6 weeks old and adult (10-12 weeks old stages. In addition, we tested the effects of D-serine on PPI deficits in adult mice after neonatal Met-Phen exposure. Finally, we assessed whether D-serine could prevent the onset of schizophrenia-like behavior in these mice. Neonatal Met-Phen treatment reduced D-serine levels in the brain, 24 hours after the final dose. Additionally, this treatment caused behavioral abnormalities relevant to prodromal symptoms in juveniles and to schizophrenia in adults. A single dose of D-serine improved PPI deficits in adult mice. Interestingly, chronic administration of D-serine (900 mg/kg/day from P35 to P70 significantly prevented the onset of PPI deficits after neonatal Met-Phen exposure.This study shows that disruption of D-serine synthesis during developmental stages leads to behavioral abnormalities relevant to prodromal symptoms and schizophrenia, in later life. Furthermore, early pharmacological intervention with D-serine may prevent the onset of psychosis in adult.

  17. A cyclic peptidic serine protease inhibitor

    DEFF Research Database (Denmark)

    Zhao, Baoyu; Xu, Peng; Jiang, Longguang

    2014-01-01

    Peptides are attracting increasing interest as protease inhibitors. Here, we demonstrate a new inhibitory mechanism and a new type of exosite interactions for a phage-displayed peptide library-derived competitive inhibitor, mupain-1 (CPAYSRYLDC), of the serine protease murine urokinase...... pocket, its carbonyl group aligning improperly relative to Ser195 and the oxyanion hole, explaining why the peptide is an inhibitor rather than a substrate. Substitution of the P1 Arg with novel unnatural Arg analogues with aliphatic or aromatic ring structures led to an increased affinity, depending......, in spite of a less favorable binding entropy and loss of a polar interaction. We conclude that increased flexibility of the peptide allows more favorable exosite interactions, which, in combination with the use of novel Arg analogues as P1 residues, can be used to manipulate the affinity and specificity...

  18. Highly potent fibrinolytic serine protease from Streptomyces.

    Science.gov (United States)

    Uesugi, Yoshiko; Usuki, Hirokazu; Iwabuchi, Masaki; Hatanaka, Tadashi

    2011-01-05

    We introduce a highly potent fibrinolytic serine protease from Streptomyces omiyaensis (SOT), which belongs to the trypsin family. The fibrinolytic activity of SOT was examined using in vitro assays and was compared with those of known fibrinolytic enzymes such as plasmin, tissue-type plasminogen activator (t-PA), urokinase, and nattokinase. Compared to other enzymes, SOT showed remarkably higher hydrolytic activity toward mimic peptides of fibrin and plasminogen. The fibrinolytic activity of SOT is about 18-fold higher than that of plasmin, and is comparable to that of t-PA by fibrin plate assays. Furthermore, SOT had some plasminogen activator-like activity. Results show that SOT and nattokinase have very different fibrinolytic and fibrinogenolytic modes, engendering significant synergetic effects of SOT and nattokinase on fibrinolysis. These results suggest that SOT presents important possibilities for application in the therapy of thrombosis. Copyright © 2010 Elsevier Inc. All rights reserved.

  19. Efficacy of Artemether in Unresolving Plasmodium Falciparum Malaria

    African Journals Online (AJOL)

    The emergence of possible resistant Plasmodium falciparum malaria to artemisinin known for its immense benefit in malaria chemotherapy is worrisome. We report a case of unresolving Plasmodium falciparum malaria to Artesunate treatment in a 29- year old man in Enugu Nigeria. Plasmodium falciparum count of Giemsa ...

  20. Enhancement of L-Serine Production by Corynebacterium ...

    African Journals Online (AJOL)

    glutamicum SYPS-062 cultivation process for efficient production of L-serine on a large scale. ... central intermediate for a number of cellular .... impeller, oxygen and pH electrodes, under the ... equation. The yield of L-serine was regressed with respect to the medium ..... is not essential for activity but is required for inhibition.

  1. D-serine : The right or wrong isoform?

    NARCIS (Netherlands)

    Fuchs, Sabine A; Berger, Ruud; de Koning, Tom J

    2011-01-01

    Only recently, d-amino acids have been identified in mammals. Of these, d-serine has been most extensively studied. d-Serine was found to play an important role as a neurotransmitter in the human central nervous system (CNS) by binding to the N-methyl-d-aspartate receptor (NMDAr), similar to

  2. Microbial Production of l-Serine from Renewable Feedstocks.

    Science.gov (United States)

    Zhang, Xiaomei; Xu, Guoqiang; Shi, Jinsong; Koffas, Mattheos A G; Xu, Zhenghong

    2018-07-01

    l-Serine is a non-essential amino acid that has wide and expanding applications in industry with a fast-growing market demand. Currently, extraction and enzymatic catalysis are the main processes for l-serine production. However, such approaches limit the industrial-scale applications of this important amino acid. Therefore, shifting to the direct fermentative production of l-serine from renewable feedstocks has attracted increasing attention. This review details the current status of microbial production of l-serine from renewable feedstocks. We also summarize the current trends in metabolic engineering strategies and techniques for the typical industrial organisms Corynebacterium glutamicum and Escherichia coli that have been developed to address and overcome major challenges in the l-serine production process. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Gametocytogenesis : the puberty of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Ariey Frédéric

    2004-07-01

    Full Text Available Abstract The protozoan Plasmodium falciparum has a complex life cycle in which asexual multiplication in the vertebrate host alternates with an obligate sexual reproduction in the anopheline mosquito. Apart from the apparent recombination advantages conferred by sex, P. falciparum has evolved a remarkable biology and adaptive phenotypes to insure its transmission despite the dangers of sex. This review mainly focuses on the current knowledge on commitment to sexual development, gametocytogenesis and the evolutionary significance of various aspects of gametocyte biology. It goes further than pure biology to look at the strategies used to improve successful transmission. Although gametocytes are inevitable stages for transmission and provide a potential target to fight malaria, they have received less attention than the pathogenic asexual stages. There is a need for research on gametocytes, which are a fascinating stage, responsible to a large extent for the success of P. falciparum.

  4. Fibrin(ogen)olytic activity of bumblebee venom serine protease

    International Nuclear Information System (INIS)

    Qiu Yuling; Choo, Young Moo; Yoon, Hyung Joo; Jia Jingming; Cui Zheng; Wang Dong; Kim, Doh Hoon; Sohn, Hung Dae; Jin, Byung Rae

    2011-01-01

    Bee venom is a rich source of pharmacologically active components; it has been used as an immunotherapy to treat bee venom hypersensitivity, and venom therapy has been applied as an alternative medicine. Here, we present evidence that the serine protease found in bumblebee venom exhibits fibrin(ogen)olytic activity. Compared to honeybee venom, bumblebee venom contains a higher content of serine protease, which is one of its major components. Venom serine proteases from bumblebees did not cross-react with antibodies against the honeybee venom serine protease. We provide functional evidence indicating that bumblebee (Bombus terrestris) venom serine protease (Bt-VSP) acts as a fibrin(ogen)olytic enzyme. Bt-VSP activates prothrombin and directly degrades fibrinogen into fibrin degradation products. However, Bt-VSP is not a plasminogen activator, and its fibrinolytic activity is less than that of plasmin. Taken together, our results define roles for Bt-VSP as a prothrombin activator, a thrombin-like protease, and a plasmin-like protease. These findings offer significant insight into the allergic reaction sequence that is initiated by bee venom serine protease and its potential usefulness as a clinical agent in the field of hemostasis and thrombosis. - Graphical abstract: Display Omitted Highlights: → Bumblebee venom serine protease (Bt-VSP) is a fibrin(ogen)olytic enzyme. → Bt-VSP activates prothrombin. → Bt-VSP directly degrades fibrinogen into fibrin degradation products. → Bt-VSP is a hemostatically active protein that is a potent clinical agent.

  5. Characterization of sequence diversity in Plasmodium falciparum SERA5 from Indian isolates

    Directory of Open Access Journals (Sweden)

    Rahul C.N

    2015-06-01

    Full Text Available Objective: To characterize the sequence diversity of blood-stage Plasmodium falciparum serine repeat antigen-5 (PfSERA5 which is lacking in a malaria-endemic country like India. Methods: In this study, parasitic DNA was obtained from field isolates collected from various geographic regions. Subsequently, PfSERA5 gene sequence was PCR amplified and DNA sequenced. Results: We reported the existence of unique repeat polymorphisms and novel haplotypes for both the octamer repeat (OR and serine repeat (SR regions of the N-terminal fragment of PfSERA5 from Indian isolates. Several isolates from India were identical to low-frequency African haplotypes. Unique finding of our study was an Indian isolate showing deletion in a perfectly conserved 14 mer sequence within octamer repeat. Indian haplotypes reported in this study were found to be distributed into the three earlier classified allelic clusters of FCR3, K1 and Honduras showcasing broad diversity as compared to worldwide haplotypes. Conclusions: This study is the first report on genetic diversity of PfSERA5 antigen from India. Further evaluation of these haplotypes by serotyping would provide useful information for investigating variant-specific immunity and aid in malaria vaccine research.

  6. Plasmodium falciparum malaria associated with ABO blood ...

    African Journals Online (AJOL)

    The present study was carried out to investigate the relationship between blood group types and P. falciparum malaria, as well as malaria preventive measures. The venous blood specimens were collected, processed, Giemsa-stained and examined microscopically. ABO groups were determined by agglutination test using ...

  7. Piperaquine Resistance in Plasmodium falciparum, West Africa.

    Science.gov (United States)

    Inoue, Juliana; Silva, Miguel; Fofana, Bakary; Sanogo, Kassim; Mårtensson, Andreas; Sagara, Issaka; Björkman, Anders; Veiga, Maria Isabel; Ferreira, Pedro Eduardo; Djimde, Abdoulaye; Gil, José Pedro

    2018-08-17

    Dihydroartemisinin/piperaquine (DHA/PPQ) is increasingly deployed as antimalaria drug in Africa. We report the detection in Mali of Plasmodium falciparum infections carrying plasmepsin 2 duplications (associated with piperaquine resistance) in 7/65 recurrent infections within 2 months after DHA/PPQ treatment. These findings raise concerns about the long-term efficacy of DHA/PPQ treatment in Africa.

  8. Plasmodium falciparum malaria and antimalarial interventions in ...

    African Journals Online (AJOL)

    Plasmodium falciparum malaria is one of the most important parasitic diseases affecting sub-Saharan Africa, despite the availability of interventions. It exerts tremendous socio-economic and medical burden on the continent, particularly in under five children and pregnant women. In this review, we have attempted to ...

  9. Alanine metabolism in acute falciparum malaria

    NARCIS (Netherlands)

    Pukrittayakamee, S.; Krishna, S.; ter Kuile, F.; Wilaiwan, O.; Williamson, D. H.; White, N. J.

    2002-01-01

    We investigated the integrity of the gluconeogenic pathway in severe malaria using alanine metabolism as a measure. Alanine disposition and liver blood flow, assessed by indocyanine green (ICG) clearance, were measured simultaneously in 10 patients with falciparum malaria (six severe and four

  10. Elimination of Plasmodium falciparum malaria in Tajikistan.

    Science.gov (United States)

    Kondrashin, Anatoly V; Sharipov, Azizullo S; Kadamov, Dilshod S; Karimov, Saifuddin S; Gasimov, Elkhan; Baranova, Alla M; Morozova, Lola F; Stepanova, Ekaterina V; Turbabina, Natalia A; Maksimova, Maria S; Morozov, Evgeny N

    2017-05-30

    Malaria was eliminated in Tajikistan by the beginning of the 1960s. However, sporadic introduced cases of malaria occurred subsequently probably as a result of transmission from infected mosquito Anopheles flying over river the Punj from the border areas of Afghanistan. During the 1970s and 1980s local outbreaks of malaria were reported in the southern districts bordering Afghanistan. The malaria situation dramatically changed during the 1990s following armed conflict and civil unrest in the newly independent Tajikistan, which paralyzed health services including the malaria control activities and a large-scale malaria epidemic occurred with more than 400,000 malaria cases. The malaria epidemic was contained by 1999 as a result of considerable financial input from the Government and the international community. Although Plasmodium falciparum constituted only about 5% of total malaria cases, reduction of its incidence was slower than that of Plasmodium vivax. To prevent increase in P. falciparum malaria both in terms of incidence and territory, a P. falciparum elimination programme in the Republic was launched in 200, jointly supported by the Government and the Global Fund for control of AIDS, tuberculosis and malaria. The main activities included the use of pyrethroids for the IRS with determined periodicity, deployment of mosquito nets, impregnated with insecticides, use of larvivorous fishes as a biological larvicide, implementation of small-scale environmental management, and use of personal protection methods by population under malaria risk. The malaria surveillance system was strengthened by the use of ACD, PCD, RCD and selective use of mass blood surveys. All detected cases were timely epidemiologically investigated and treated based on the results of laboratory diagnosis. As a result, by 2009, P. falciparum malaria was eliminated from all of Tajikistan, one year ahead of the originally targeted date. Elimination of P. falciparum also contributed towards

  11. Pooled-DNA sequencing identifies genomic regions of selection in Nigerian isolates of Plasmodium falciparum.

    Science.gov (United States)

    Oyebola, Kolapo M; Idowu, Emmanuel T; Olukosi, Yetunde A; Awolola, Taiwo S; Amambua-Ngwa, Alfred

    2017-06-29

    The burden of falciparum malaria is especially high in sub-Saharan Africa. Differences in pressure from host immunity and antimalarial drugs lead to adaptive changes responsible for high level of genetic variations within and between the parasite populations. Population-specific genetic studies to survey for genes under positive or balancing selection resulting from drug pressure or host immunity will allow for refinement of interventions. We performed a pooled sequencing (pool-seq) of the genomes of 100 Plasmodium falciparum isolates from Nigeria. We explored allele-frequency based neutrality test (Tajima's D) and integrated haplotype score (iHS) to identify genes under selection. Fourteen shared iHS regions that had at least 2 SNPs with a score > 2.5 were identified. These regions code for genes that were likely to have been under strong directional selection. Two of these genes were the chloroquine resistance transporter (CRT) on chromosome 7 and the multidrug resistance 1 (MDR1) on chromosome 5. There was a weak signature of selection in the dihydrofolate reductase (DHFR) gene on chromosome 4 and MDR5 genes on chromosome 13, with only 2 and 3 SNPs respectively identified within the iHS window. We observed strong selection pressure attributable to continued chloroquine and sulfadoxine-pyrimethamine use despite their official proscription for the treatment of uncomplicated malaria. There was also a major selective sweep on chromosome 6 which had 32 SNPs within the shared iHS region. Tajima's D of circumsporozoite protein (CSP), erythrocyte-binding antigen (EBA-175), merozoite surface proteins - MSP3 and MSP7, merozoite surface protein duffy binding-like (MSPDBL2) and serine repeat antigen (SERA-5) were 1.38, 1.29, 0.73, 0.84 and 0.21, respectively. We have demonstrated the use of pool-seq to understand genomic patterns of selection and variability in P. falciparum from Nigeria, which bears the highest burden of infections. This investigation identified known

  12. ACTIVATION OF A CRYPTIC D-SERINE DEAMINASE (DSD) GENE FROM PSEUDOMONAS CEPACIA 17616

    Science.gov (United States)

    D-serine inhibits growth of P. cepacia 17616; however, resistant mutants able to express an ordinarily cryptic D-serine deaminase (dsd) gene were isolated readily. The resistant strains formed high levels of a D-serine deaminase active on D-threonine as well as D-serine. IS eleme...

  13. Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

    Science.gov (United States)

    Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

    2016-11-23

    Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

  14. Cross genome comparisons of serine proteases in Arabidopsis and rice

    Directory of Open Access Journals (Sweden)

    Sowdhamini R

    2006-08-01

    Full Text Available Abstract Background Serine proteases are one of the largest groups of proteolytic enzymes found across all kingdoms of life and are associated with several essential physiological pathways. The availability of Arabidopsis thaliana and rice (Oryza sativa genome sequences has permitted the identification and comparison of the repertoire of serine protease-like proteins in the two plant species. Results Despite the differences in genome sizes between Arabidopsis and rice, we identified a very similar number of serine protease-like proteins in the two plant species (206 and 222, respectively. Nearly 40% of the above sequences were identified as potential orthologues. Atypical members could be identified in the plant genomes for Deg, Clp, Lon, rhomboid proteases and species-specific members were observed for the highly populated subtilisin and serine carboxypeptidase families suggesting multiple lateral gene transfers. DegP proteases, prolyl oligopeptidases, Clp proteases and rhomboids share a significantly higher percentage orthology between the two genomes indicating substantial evolutionary divergence was set prior to speciation. Single domain architectures and paralogues for several putative subtilisins, serine carboxypeptidases and rhomboids suggest they may have been recruited for additional roles in secondary metabolism with spatial and temporal regulation. The analysis reveals some domain architectures unique to either or both of the plant species and some inactive proteases, like in rhomboids and Clp proteases, which could be involved in chaperone function. Conclusion The systematic analysis of the serine protease-like proteins in the two plant species has provided some insight into the possible functional associations of previously uncharacterised serine protease-like proteins. Further investigation of these aspects may prove beneficial in our understanding of similar processes in commercially significant crop plant species.

  15. Microstructure and nanomechanical properties of enamel remineralized with asparagine-serine-serine peptide

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hsiu-Ying, E-mail: hychung@mail.fcu.edu.tw; Li, Cheng Che

    2013-03-01

    A highly biocompatible peptide, triplet repeats of asparagine-serine-serine (3NSS) was designed to regulate mineral deposition from aqueous ions in saliva for the reconstruction of enamel lesions. Healthy human enamel was sectioned and acid demineralized to create lesions, then exposed to the 3NSS peptide solution, and finally immersed in artificial saliva for 24 h. The surface morphology and roughness were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. X-ray diffraction (XRD) was used to identify the phases and crystallinity of the deposited minerals observed on the enamel surface. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to quantitatively analyze the mineral variation by calculating the relative integrated-area of characteristic bands. Nanohardness and elastic modulus measured by nanoindentation at various treatment stages were utilized to evaluate the degree of recovery. Biomimetic effects were accessed according to the degree of nanohardness recovery and the amount of hydroxyapatite deposition. The charged segments in the 3NSS peptide greatly attracted aqueous ions from artificial saliva to form hydroxyapatite crystals to fill enamel caries, in particular the interrod areas, resulting in a slight reduction in overall surface roughness. Additionally, the deposited hydroxyapatites were of a small crystalline size in the presence of the 3NSS peptide, which effectively restrained the plastic deformations and thus resulted in greater improvements in nanohardness and elastic modulus. The degree of nanohardness recovery was 5 times greater for remineralized enamel samples treated with the 3NSS peptide compared to samples without peptide treatment. - Highlights: Black-Right-Pointing-Pointer The degree of nanohardness recovery of enamel was 4 times greater with the aid of 3NSS peptide. Black-Right-Pointing-Pointer 3NSS peptide promoted the formation of hydroxyapatites with

  16. The binding mechanism of a peptidic cyclic serine protease inhibitor

    DEFF Research Database (Denmark)

    Jiang, Longguang; Svane, Anna Sigrid P.; Sørensen, Hans Peter

    2011-01-01

    Serine proteases are classical objects for studies of catalytic and inhibitory mechanisms as well as interesting as therapeutic targets. Since small-molecule serine protease inhibitors generally suffer from specificity problems, peptidic inhibitors, isolated from phage-displayed peptide libraries......, have attracted considerable attention. Here, we have investigated the mechanism of binding of peptidic inhibitors to serine protease targets. Our model is upain-1 (CSWRGLENHRMC), a disulfide-bond-constrained competitive inhibitor of human urokinase-type plasminogen activator with a noncanonical...... inhibitory mechanism and an unusually high specificity. Using a number of modified variants of upain-1, we characterised the upain-1-urokinase-type plasminogen activator complex using X-ray crystal structure analysis, determined a model of the peptide in solution by NMR spectroscopy, and analysed binding...

  17. Mosaic serine proteases in the mammalian central nervous system.

    Science.gov (United States)

    Mitsui, Shinichi; Watanabe, Yoshihisa; Yamaguchi, Tatsuyuki; Yamaguchi, Nozomi

    2008-01-01

    We review the structure and function of three kinds of mosaic serine proteases expressed in the mammalian central nervous system (CNS). Mosaic serine proteases have several domains in the proenzyme fragment, which modulate proteolytic function, and a protease domain at the C-terminus. Spinesin/TMPRSS5 is a transmembrane serine protease whose presynaptic distribution on motor neurons in the spinal cord suggests that it is significant for neuronal plasticity. Cell type-specific alternative splicing gives this protease diverse functions by modulating its intracellular localization. Motopsin/PRSS12 is a mosaic protease, and loss of its function causes mental retardation. Recent reports indicate the significance of this protease for cognitive function. We mention the fibrinolytic protease, tissue plasminogen activator (tPA), which has physiological and pathological functions in the CNS.

  18. Dosage compensation of serine-4 transfer RNA in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Birchler, J.A.; Owenby, R.K.; Jacobson, K.B.

    1982-01-01

    A dosage series of the X chromosome site for serine-4 transfer RNA consisting of one of three copies in females and one to two in males was constructed to test whether transfer RNA expression is governed by dosage compensation. A dosage effect on the level of the serine-4 isoacceptor was observed in both females and males when the structural locus was varied. However, in males, each dose had a relatively greater expression so the normal one dose was slightly greater than the total female value and the duplicated male had the highest relative expression of all the types examined. Serine-4 levels in males and females from an isogenic Oregon-R stock were similar. Thus the transfer RNA levels conform to the expectations of dosage compensation

  19. Interleukin-10 regulates hepcidin in Plasmodium falciparum malaria

    KAUST Repository

    Huang, Honglei; Lamikanra, Abigail A.; Alkaitis, Matthew S.; Thé zé nas, Marie L.; Ramaprasad, Abhinay; Moussa, Ehab; Roberts, David J.; Casals-Pascual, Climent

    2014-01-01

    . falciparum malaria. Methods: We have measured secretion of hepcidin by primary macrophages and the hepatoma cell line HepG2 stimulated with IL-10, IL-6 and Plasmodium falciparum-infected erythrocytes. Findings: We have observed that IL-10 and IL-6 production

  20. Immune evasion of Plasmodium falciparum by RIFIN via inhibitory receptors

    DEFF Research Database (Denmark)

    Saito, Fumiji; Hirayasu, Kouyuki; Satoh, Takeshi

    2017-01-01

    , but the immune regulatory mechanisms used by P. falciparum remain largely unknown. Here we show that P. falciparum uses immune inhibitory receptors to achieve immune evasion. RIFIN proteins are products of a polymorphic multigene family comprising approximately 150-200 genes per parasite genome...

  1. Artemisinin resistance marker of Plasmodium falciparum in Osogbo ...

    African Journals Online (AJOL)

    Artemisinin derivatives constitute a key component of the present-day treatment for Plasmodium falciparum malaria. Resistance with artemisinins is generally associated with S769N point mutation in the sarco-endoplasmic reticulumdependant ATPase6 (SERCA ATPase6) gene of Plasmodium falciparum, few studies have ...

  2. Prevalence of falciparum malaria amongst pregnant women in Aba ...

    African Journals Online (AJOL)

    Malaria during pregnancy poses a substantial risk to mother and foetus especially an infection with Plasmodium falciparum. This study was undertaken to assess the prevalence of falciparum malaria among pregnant women in Aba South Local Government Area, Abia State, south-east Nigeria. Blood samples from 432 ...

  3. Population genomics diversity of Plasmodium falciparum in malaria ...

    African Journals Online (AJOL)

    Background: Plasmodium falciparum, the most dangerous malaria parasite species to humans remains an important public health concern in Okelele, a rural community in Ilorin, Kwara State, Nigeria. There is however little information about the genetic diversity of Plasmodium falciparum in Nigeria. Objective: To determine ...

  4. Convergent synthesis of a deuterium-labeled serine dipeptide lipid for analysis of biological samples.

    Science.gov (United States)

    Dietz, Christopher; Clark, Robert B; Nichols, Frank C; Smith, Michael B

    2017-05-30

    Bacterial serine dipeptide lipids are known to promote inflammatory processes and are detected in human tissues associated with periodontal disease or atherosclerosis. Accurate quantification of bacterial serine lipid, specifically lipid 654 [((S)-15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, (3S)-l-serine] isolated from Porphyromonas gingivalis, in biological samples requires the preparation of a stable isotope internal standard for sample supplementation and subsequent mass spectrometric analysis. This report describes the convergent synthesis of a deuterium-substituted serine dipeptide lipid, which is an isotopically labeled homologue that represents a dominant form of serine dipeptide lipid recovered in bacteria. Copyright © 2017 John Wiley & Sons, Ltd.

  5. The VA, VCD, Raman and ROA spectra of tri-L-serine in aqueous solution

    DEFF Research Database (Denmark)

    Jürgensen, Vibeke Würtz; Jalkanen, Karl J.

    2006-01-01

    The structures of one conformer of the nonionic neutral and zwitterionic species of L-serinyl L-serinyl L-serine (SSS or tri-L-serine), together with its cationic and anionic species and the capped N-acetyl tri-L-serine N'-methylamide analog were optimized with density functional theory with the ......The structures of one conformer of the nonionic neutral and zwitterionic species of L-serinyl L-serinyl L-serine (SSS or tri-L-serine), together with its cationic and anionic species and the capped N-acetyl tri-L-serine N'-methylamide analog were optimized with density functional theory...

  6. Fatal cerebral edema associated with serine deficiency in CSF

    NARCIS (Netherlands)

    Keularts, Irene M. L. W.; Leroy, Piet L. J. M.; Rubio-Gozalbo, Estela M.; Spaapen, Leo J. M.; Weber, Biene; Dorland, Bert; de Koning, Tom J.; Verhoeven-Duif, Nanda M.

    2010-01-01

    Two young girls without a notable medical history except for asthma presented with an acute toxic encephalopathy with very low serine concentrations both in plasma and cerebrospinal fluid (CSF) comparable to patients with 3-phosphoglycerate dehydrogenase (3-PGDH) deficiency. Clinical symptoms and

  7. The Hunger Games: p53 regulates metabolism upon serine starvation.

    Science.gov (United States)

    Tavana, Omid; Gu, Wei

    2013-02-05

    Cancer cells reprogram their metabolism to support a high proliferative rate. A new study shows that, upon serine starvation, the tumor suppressor p53 activates p21 to shift metabolic flux from purine biosynthesis to glutathione production, which enhances cellular proliferation and viability by combating ROS (Maddocks et al., 2013). Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Serine protease from midgut of Bombus terrestris males

    Czech Academy of Sciences Publication Activity Database

    Brabcová, Jana; Kindl, Jiří; Valterová, Irena; Pichová, Iva; Zarevúcka, Marie; Brabcová, J.; Jágr, Michal; Mikšík, Ivan

    2013-01-01

    Roč. 82, č. 3 (2013), s. 117-128 ISSN 0739-4462 R&D Projects: GA ČR GA203/09/1446; GA TA ČR TA01020969 Institutional support: RVO:61388963 ; RVO:67985823 Keywords : Bombus terrestris * midgut * serine protease * bumblebee Subject RIV: CE - Biochemistry; CE - Biochemistry (FGU-C) Impact factor: 1.160, year: 2013

  9. Sphingoid bases and the serine catabolic enzyme CHA1 define a novel feedforward/feedback mechanism in the response to serine availability.

    Science.gov (United States)

    Montefusco, David J; Newcomb, Benjamin; Gandy, Jason L; Brice, Sarah E; Matmati, Nabil; Cowart, L Ashley; Hannun, Yusuf A

    2012-03-16

    Targets of bioactive sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that sphingolipids may mediate the induction of Cha1 in response to serine availability. The results showed that inhibition of de novo synthesis of sphingolipids, pharmacologically or genetically, prevented the induction of Cha1 in response to increased serine availability. Additional studies implicated the sphingoid bases phytosphingosine and dihydrosphingosine as the likely mediators of Cha1 up-regulation. The yeast protein kinases Pkh1 and Pkh2, known sphingoid base effectors, were found to mediate CHA1 up-regulation via the transcription factor Cha4. Because the results disclosed a role for sphingolipids in negative feedback regulation of serine metabolism, we investigated the effects of disrupting this mechanism on sphingolipid levels and on cell growth. Intriguingly, exposure of the cha1Δ strain to high serine resulted in hyperaccumulation of endogenous serine and in turn a significant accumulation of sphingoid bases and ceramides. Under these conditions, the cha1Δ strain displayed a significant growth defect that was sphingolipid-dependent. Together, this work reveals a feedforward/feedback loop whereby the sphingoid bases serve as sensors of serine availability and mediate up-regulation of Cha1 in response to serine availability, which in turn regulates sphingolipid levels by limiting serine accumulation.

  10. Proteomics methods applied to malaria: Plasmodium falciparum

    International Nuclear Information System (INIS)

    Cuesta Astroz, Yesid; Segura Latorre, Cesar

    2012-01-01

    Malaria is a parasitic disease that has a high impact on public health in developing countries. The sequencing of the plasmodium falciparum genome and the development of proteomics have enabled a breakthrough in understanding the biology of the parasite. Proteomics have allowed to characterize qualitatively and quantitatively the parasite s expression of proteins and has provided information on protein expression under conditions of stress induced by antimalarial. Given the complexity of their life cycle, this takes place in the vertebrate host and mosquito vector. It has proven difficult to characterize the protein expression during each stage throughout the infection process in order to determine the proteome that mediates several metabolic, physiological and energetic processes. Two dimensional electrophoresis, liquid chromatography and mass spectrometry have been useful to assess the effects of antimalarial on parasite protein expression and to characterize the proteomic profile of different p. falciparum stages and organelles. The purpose of this review is to present state of the art tools and advances in proteomics applied to the study of malaria, and to present different experimental strategies used to study the parasite's proteome in order to show the advantages and disadvantages of each one.

  11. Engineering of High Yield Production of L-serine in Escherichia coli

    DEFF Research Database (Denmark)

    Mundhada, Hemanshu; Schneider, Konstantin; Christensen, Hanne Bjerre

    2016-01-01

    by deletion of three L-serine deaminases sdaA, sdaB, and tdcG, as well as serine hydroxyl methyl transferase (SHMT) encoded by glyA. Upon overexpression of the serine production pathway, consisting of a feedback resistant version of serA along with serB and serC, this quadruple deletion strain showed a very...

  12. Antinociceptive Effect of Rat D-Serine Racemase Inhibitors, L-Serine-O-Sulfate, and L-Erythro-3-Hydroxyaspartate in an Arthritic Pain Model

    Directory of Open Access Journals (Sweden)

    Claudio Laurido

    2012-01-01

    Full Text Available N-methyl-D-aspartic acid receptor (NMDAr activation requires the presence of D-serine, synthesized from L-serine by a pyridoxal 5′-phosphate-dependent serine racemase (SR. D-serine levels can be lowered by inhibiting the racemization of L-serine. L-serine-O-sulfate (LSOS and L-erythro-3-hydroxyaspartate (LEHA, among others, have proven to be effective in reducing the D-serine levels in culture cells. It is tempting then to try these compounds in their effectiveness to decrease nociceptive levels in rat arthritic pain. We measured the C-reflex paradigm and wind-up potentiation in the presence of intrathecally injected LSOS (100 μg/10 μL and LEHA (100 μg/10 μL in normal and monoarthritic rats. Both compounds decreased the wind-up activity in normal and monoarthritic rats. Accordingly, all the antinociceptive effects were abolished when 300 μg/10 μL of D-serine were injected intrathecally. Since no in vivo results have been presented so far, this constitutes the first evidence that SR inhibitions lower the D-serine levels, thus decreasing the NMDAr activity and the consequent development and maintenance of chronic pain.

  13. Intervention with Serine Protease Activity with Small Peptides

    DEFF Research Database (Denmark)

    Xu, Peng

    2015-01-01

    Serine proteases perform proteolytic reactions in many physiological and metabolic processes and have been certified as targets for therapeutics. Small peptides can be used as potent antagonists to target serine proteases and intervene with their activities. Urokinase-type plasminogen activator (u......PA) plays an important role in plasminogen activation system, which has many physiological and pathological functions and is closely associated with the metastasis of tumor cells. Based on a mono-cyclic peptidic inhibitor of murine uPA (muPA), mupain-1, which was screened out from a phage-display library...... before, we elucidated the binding and inhibitory mechanism by using multiple techniques, like X-ray crystallography, site-directed mutagenesis, isothermal titration calorimetry and surface plasmon resonance analysis. By studying the peptide-enzyme interaction, we discovered an unusual inhibitor...

  14. Site-specific DNA Inversion by Serine Recombinases

    Science.gov (United States)

    2015-01-01

    Reversible site-specific DNA inversion reactions are widely distributed in bacteria and their viruses. They control a range of biological reactions that most often involve alterations of molecules on the surface of cells or phage. These programmed DNA rearrangements usually occur at a low frequency, thereby preadapting a small subset of the population to a change in environmental conditions, or in the case of phages, an expanded host range. A dedicated recombinase, sometimes with the aid of additional regulatory or DNA architectural proteins, catalyzes the inversion of DNA. RecA or other components of the general recombination-repair machinery are not involved. This chapter discusses site-specific DNA inversion reactions mediated by the serine recombinase family of enzymes and focuses on the extensively studied serine DNA invertases that are stringently controlled by the Fis-bound enhancer regulatory system. The first section summarizes biological features and general properties of inversion reactions by the Fis/enhancer-dependent serine invertases and the recently described serine DNA invertases in Bacteroides. Mechanistic studies of reactions catalyzed by the Hin and Gin invertases are then discussed in more depth, particularly with regards to recent advances in our understanding of the function of the Fis/enhancer regulatory system, the assembly of the active recombination complex (invertasome) containing the Fis/enhancer, and the process of DNA strand exchange by rotation of synapsed subunit pairs within the invertasome. The role of DNA topological forces that function in concert with the Fis/enhancer controlling element in specifying the overwhelming bias for DNA inversion over deletion and intermolecular recombination is emphasized. PMID:25844275

  15. On Programmed Cell Death in Plasmodium falciparum: Status Quo

    Directory of Open Access Journals (Sweden)

    Dewaldt Engelbrecht

    2012-01-01

    Full Text Available Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction.

  16. On Programmed Cell Death in Plasmodium falciparum: Status Quo

    Science.gov (United States)

    Engelbrecht, Dewaldt; Durand, Pierre Marcel; Coetzer, Thérèsa Louise

    2012-01-01

    Conflicting arguments and results exist regarding the occurrence and phenotype of programmed cell death (PCD) in the malaria parasite Plasmodium falciparum. Inconsistencies relate mainly to the number and type of PCD markers assessed and the different methodologies used in the studies. In this paper, we provide a comprehensive overview of the current state of knowledge and empirical evidence for PCD in the intraerythrocytic stages of P. falciparum. We consider possible reasons for discrepancies in the data and offer suggestions towards more standardised investigation methods in this field. Furthermore, we present genomic evidence for PCD machinery in P. falciparum. We discuss the potential adaptive or nonadaptive role of PCD in the parasite life cycle and its possible exploitation in the development of novel drug targets. Lastly, we pose pertinent unanswered questions concerning the PCD phenomenon in P. falciparum to provide future direction. PMID:22287973

  17. Cryo scanning electron microscopy of Plasmodium falciparum-infected erythrocytes

    DEFF Research Database (Denmark)

    Hempel, Casper

    2017-01-01

    Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions...

  18. Genetic polymorphism of Plasmodium falciparum isolates from Loreto, Peru.

    Science.gov (United States)

    Hijar, Gisely; Padilla, Carlos; Marquiño, Wilmer; Falconi, Eduardo; Montoya, Ysabel

    2002-04-01

    Eight genotypes of Plasmodium falciparum were detected after analysing blood samples obtained from 30 Peruvian jungle-dwelling patients in Loreto, a high transmission area for P. falciparum, using amplification of the polymorphic marker gene GLURP (glutamate-rich protein). Genotypes I (GLURP450) and VIII (GLURP800) were the most common (15/30 and 13/30, respectively). This single copy gene showed 15 patients to be infected with a single genotype of P. falciparum; the other 15 were infected with mixed genotypes, one of them with 4 genotypes. These findings are compatible with a high genetic complexity of P. falciparum. Further investigations are needed, using this and other markers, in order to design malaria control measures in Peru.

  19. Optimization of a protocol for extraction of Plasmodium falciparum ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-05-16

    May 16, 2008 ... compared to saponin lysed samples when such whole blood ... infected blood intended for extraction of P. falciparum RNA for DNA microarrays and other sensitive ... TaqMan® and LightCycler® technology, and other.

  20. Impact of Plasmodium falciparum and hookworm infections on the ...

    African Journals Online (AJOL)

    abp

    2013-01-18

    Saharan Africa and they increase the prevalence of anaemia in pregnancy with resultant poor pregnancy outcomes. This study was carried out to assess the impact of Plasmodium falciparum and hookworm infections on.

  1. Peripheral blood cell signatures of Plasmodium falciparum infection during pregnancy

    DEFF Research Database (Denmark)

    Ibitokou, Samad; Oesterholt, Mayke; Brutus, Laurent

    2012-01-01

    Sequestration of Plasmodium falciparum-infected erythrocytes in placental intervillous spaces causes inflammation and pathology. Knowledge of the profiles of immune cells associated with the physiopathology of pregnancy-associated malaria (PAM) is scarce. We conducted a longitudinal, prospective ...

  2. Fine-scale genetic characterization of Plasmodium falciparum ...

    Indian Academy of Sciences (India)

    RESEARCH ARTICLE. Fine-scale genetic characterization of Plasmodium falciparum .... Materials and methods. The DNA ... the order and location of genes (as per the PlasmoDB data resources, available at ... There is currently an. Figure 5.

  3. Spatial and temporal distribution of falciparum malaria in China

    Directory of Open Access Journals (Sweden)

    Lin Hualiang

    2009-06-01

    Full Text Available Abstract Background Falciparum malaria is the most deadly among the four main types of human malaria. Although great success has been achieved since the launch of the National Malaria Control Programme in 1955, malaria remains a serious public health problem in China. This paper aimed to analyse the geographic distribution, demographic patterns and time trends of falciparum malaria in China. Methods The annual numbers of falciparum malaria cases during 1992–2003 and the individual case reports of each clinical falciparum malaria during 2004–2005 were extracted from communicable disease information systems in China Center for Diseases Control and Prevention. The annual number of cases and the annual incidence were mapped by matching them to corresponding province- and county-level administrative units in a geographic information system. The distribution of falciparum malaria by age, gender and origin of infection was analysed. Time-series analysis was conducted to investigate the relationship between the falciparum malaria in the endemic provinces and the imported falciparum malaria in non-endemic provinces. Results Falciparum malaria was endemic in two provinces of China during 2004–05. Imported malaria was reported in 26 non-endemic provinces. Annual incidence of falciparum malaria was mapped at county level in the two endemic provinces of China: Yunnan and Hainan. The sex ratio (male vs. female for the number of cases in Yunnan was 1.6 in the children of 0–15 years and it reached 5.7 in the adults over 15 years of age. The number of malaria cases in Yunnan was positively correlated with the imported malaria of concurrent months in the non-endemic provinces. Conclusion The endemic area of falciparum malaria in China has remained restricted to two provinces, Yunnan and Hainan. Stable transmission occurs in the bordering region of Yunnan and the hilly-forested south of Hainan. The age and gender distribution in the endemic area is

  4. Antibacterial activity of silver nanoparticles synthesized from serine

    Energy Technology Data Exchange (ETDEWEB)

    Jayaprakash, N. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); SRM Valliammai Engineering College, Department of Chemistry, Chennai 603 203 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); John Kennedy, L. [Materials Division, School of Advanced Sciences, VIT University, Chennai Campus, Chennai 600 048 (India); Priadharsini, K.; Palani, P. [Department of Center for Advanced Study in Botany, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2015-04-01

    Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV–Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443 nm. The emission spectrum of Ag NPs showed an emission band at 484 nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO{sub 3} against Gram-positive and Gram-negative bacteria. - Highlights: • Microwave irradiation method is used to synthesize silver nanoparticles. • Highly stable silver nanoparticles are produced from serine. • A detailed study of antibacterial activities is discussed. • Formation mechanism of silver microspheres has been proposed.

  5. Pnserpin: A Novel Serine Protease Inhibitor from Extremophile Pyrobaculum neutrophilum

    Directory of Open Access Journals (Sweden)

    Huan Zhang

    2017-01-01

    Full Text Available Serine protease inhibitors (serpins are native inhibitors of serine proteases, constituting a large protein family with members spread over eukaryotes and prokaryotes. However, only very few prokaryotic serpins, especially from extremophiles, have been characterized to date. In this study, Pnserpin, a putative serine protease inhibitor from the thermophile Pyrobaculum neutrophilum, was overexpressed in Escherichia coli for purification and characterization. It irreversibly inhibits chymotrypsin-, trypsin-, elastase-, and subtilisin-like proteases in a temperature range from 20 to 100 °C in a concentration-dependent manner. The stoichiometry of inhibition (SI of Pnserpin for proteases decreases as the temperature increases, indicating that the inhibitory activity of Pnserpin increases with the temperature. SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that Pnserpin inhibits proteases by forming a SDS-resistant covalent complex. Homology modeling and molecular dynamic simulations predicted that Pnserpin can form a stable common serpin fold. Results of the present work will help in understanding the structural and functional characteristics of thermophilic serpin and will broaden the current knowledge about serpins from extremophiles.

  6. ATM-mediated Snail Serine 100 phosphorylation regulates cellular radiosensitivity

    International Nuclear Information System (INIS)

    Boohaker, Rebecca J.; Cui, Xiaoli; Stackhouse, Murray; Xu, Bo

    2013-01-01

    Purpose: Activation of the DNA damage responsive protein kinase ATM is a critical step for cellular survival in response to ionizing irradiation (IR). Direct targets of ATM regulating radiosensitivity remain to be fully investigated. We have recently reported that ATM phosphorylates the transcriptional repressor Snail on Serine 100. We aimed to further study the functional significance of ATM-mediated Snail phosphorylation in response to IR. Material and methods: We transfected vector-only, wild-type, the Serine 100 to alanine (S100A) or to glutamic acid (S100E) substitution of Snail into various cell lines. We assessed colony formation, γ-H2AX focus formation and the invasion index in the cells treated with or without IR. Results: We found that over-expression of the S100A mutant Snail in HeLa cells significantly increased radiosensitivity. Meanwhile the expression of S100E, a phospho-mimicking mutation, resulted in enhanced radio-resistance. Interestingly, S100E could rescue the radiosensitive phenotype in ATM-deficient cells. We also found that expression of S100E increased γ-H2AX focus formation and compromised inhibition of invasion in response to IR independent of cell survival. Conclusion: ATM-mediated Snail Serine 100 phosphorylation in response to IR plays an important part in the regulation of radiosensitivity

  7. Plasmodium falciparum uses vitamin E to avoid oxidative stress

    OpenAIRE

    Sussmann, Rodrigo A. C.; Fotoran, Wesley L.; Kimura, Emilia A.; Katzin, Alejandro M.

    2017-01-01

    Background Plasmodium falciparum is sensitive to oxidative stress in vitro and in vivo, and many drugs such as artemisinin, chloroquine and cercosporin interfere in the parasite’s redox system. To minimize the damage caused by reactive radicals, antioxidant enzymes and their substrates found in parasites and in erythrocytes must be functionally active. It was shown that P. falciparum synthesizes vitamin E and that usnic acid acts as an inhibitor of its biosynthesis. Vitamin E is a potent anti...

  8. The dynamics of natural Plasmodium falciparum infections.

    Directory of Open Access Journals (Sweden)

    Ingrid Felger

    Full Text Available BACKGROUND: Natural immunity to Plasmodium falciparum has been widely studied, but its effects on parasite dynamics are poorly understood. Acquisition and clearance rates of untreated infections are key elements of the dynamics of malaria, but estimating these parameters is challenging because of frequent super-infection and imperfect detectability of parasites. Consequently, information on effects of host immune status or age on infection dynamics is fragmentary. METHODS: An age-stratified cohort of 347 individuals from Northern Ghana was sampled six times at 2 month intervals. High-throughput capillary electrophoresis was used to genotype the msp-2 locus of all P. falciparum infections detected by PCR. Force of infection (FOI and duration were estimated for each age group using an immigration-death model that allows for imperfect detection of circulating parasites. RESULTS: Allowing for imperfect detection substantially increased estimates of FOI and duration. Effects of naturally acquired immunity on the FOI and duration would be reflected in age dependence in these indices, but in our cohort data FOI tended to increase with age in children. Persistence of individual parasite clones was characteristic of all age-groups. Duration peaked in 5-9 year old children (average duration 319 days, 95% confidence interval 318;320. CONCLUSIONS: The main age-dependence is on parasite densities, with only small age-variations in the FOI and persistence of infections. This supports the hypothesis that acquired immunity controls transmission mainly by limiting blood-stage parasite densities rather than changing rates of acquisition or clearance of infections.

  9. Evaluation of oxidative stress in D-serine induced nephrotoxicity

    International Nuclear Information System (INIS)

    Orozco-Ibarra, Marisol; Medina-Campos, Omar Noel; Sanchez-Gonzalez, Dolores Javier; Martinez-Martinez, Claudia Maria; Floriano-Sanchez, Esau; Santamaria, Abel; Ramirez, Victoria; Bobadilla, Norma A.; Pedraza-Chaverri, Jose

    2007-01-01

    It has been suggested that oxidative stress is involved in D-serine-induced nephrotoxicity. The purpose of this study was to assess if oxidative stress is involved in this experimental model using several approaches including (a) the determination of several markers of oxidative stress and the activity of some antioxidant enzymes in kidney and (b) the use of compounds with antioxidant or prooxidant effects. Rats were sacrificed at several periods of time (from 3 to 24 h) after a single i.p. injection of D-serine (400 mg/kg). Control rats were injected with L-serine (400 mg/kg) and sacrificed 24 h after. The following markers were used to assess the temporal aspects of renal damage: (a) urea nitrogen (BUN) and creatinine in blood serum, (b) kidney injury molecule (KIM-1) mRNA levels, and (c) tubular necrotic damage. In addition, creatinine clearance, proteinuria, and urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) were measured 24 h after D-serine injection. Protein carbonyl content, malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), fluorescent products of lipid peroxidation, reactive oxygen species (ROS), glutathione (GSH) content, and heme oxygenase-1 (HO-1) expression were measured as markers of oxidative stress in the kidney. Additional experiments were performed using the following compounds with antioxidant or pro-oxidant effects before D-serine injection: (a) α-phenyl-tert-butyl-nitrone (PBN), a spin trapping agent; (b) 5,10,15,20-tetrakis (4-sulfonatophenyl) porphyrinato iron(III) (FeTPPS), a soluble complex able to metabolize peroxynitrite; (c) aminotriazole (ATZ), a catalase (CAT) inhibitor; (d) stannous chloride (SnCl 2 ), an HO-1 inductor; (e) tin mesoporphyrin (SnMP), an HO inhibitor. In the time-course study, serum creatinine and BUN increased significantly on 15-24 and 20-24 h, respectively, and KIM-1 mRNA levels increased significantly on 6-24 h. Histological analyses revealed tubular necrosis at 12 h. The activity of antioxidant enzymes

  10. Primaquine for reducing Plasmodium falciparum transmission.

    Science.gov (United States)

    Graves, Patricia M; Gelband, Hellen; Garner, Paul

    2012-09-12

    Mosquitoes become infected with malaria when they ingest gametocyte stages of the parasite from the blood of a human host. Plasmodium falciparum gametocytes are sensitive to the drug primaquine (PQ). The World Health Organization (WHO) recommends giving a single dose or short course of PQ alongside primary treatment for people ill with P. falciparum infection to reduce malaria transmission. Gametocytes themselves cause no symptoms, so this intervention does not directly benefit individuals. PQ causes haemolysis in some people with glucose-6-phosphate dehydrogenase (G6PD) deficiency so may not be safe.   To assess whether a single dose or short course of PQ added to treatments for malaria caused by P. falciparum infection reduces malaria transmission and is safe. We searched the following databases up to 10 April 2012 for studies: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; metaRegister of Controlled Trials (mRCT) and the WHO trials search portal using 'malaria*', 'falciparum', and 'primaquine' as search terms. In addition, we searched conference proceedings and reference lists of included studies, and we contacted likely researchers and organizations for relevant trials. Trials of mass treatment of whole populations (or actively detected fever or malaria cases within such populations) with antimalarial drugs, compared to treatment with the same drug plus PQ; or patients with clinical malaria being treated for malaria at health facilities randomized to short course/single dose PQ versus no PQ. Two authors (PMG and HG) independently screened all abstracts, applied inclusion criteria, and abstracted data. We sought data on the effect of PQ on malaria transmission intensity, participant infectiousness, the number of participants with gametocytes, and gametocyte density over time. We stratified results by primary treatment drug as

  11. Expression and Characterization of Coprothermobacter proteolyticus Alkaline Serine Protease

    Directory of Open Access Journals (Sweden)

    Tanveer Majeed

    2013-01-01

    Full Text Available A putative protease gene (aprE from the thermophilic bacterium Coprothermobacter proteolyticus was cloned and expressed in Bacillus subtilis. The enzyme was determined to be a serine protease based on inhibition by PMSF. Biochemical characterization demonstrated that the enzyme had optimal activity under alkaline conditions (pH 8–10. In addition, the enzyme had an elevated optimum temperature (60°C. The protease was also stable in the presence of many surfactants and oxidant. Thus, the C. proteolyticus protease has potential applications in industries such as the detergent market.

  12. Initial characterization of the Pf-Int recombinase from the malaria parasite Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Mehdi Ghorbal

    Full Text Available Genetic variation is an essential means of evolution and adaptation in many organisms in response to environmental change. Certain DNA alterations can be carried out by site-specific recombinases (SSRs that fall into two families: the serine and the tyrosine recombinases. SSRs are seldom found in eukaryotes. A gene homologous to a tyrosine site-specific recombinase has been identified in the genome of Plasmodium falciparum. The sequence is highly conserved among five other members of Plasmodia.The predicted open reading frame encodes for a ∼57 kDa protein containing a C-terminal domain including the putative tyrosine recombinase conserved active site residues R-H-R-(H/W-Y. The N-terminus has the typical alpha-helical bundle and potentially a mixed alpha-beta domain resembling that of λ-Int. Pf-Int mRNA is expressed differentially during the P. falciparum erythrocytic life stages, peaking in the schizont stage. Recombinant Pf-Int and affinity chromatography of DNA from genomic or synthetic origin were used to identify potential DNA targets after sequencing or micro-array hybridization. Interestingly, the sequences captured also included highly variable subtelomeric genes such as var, rif, and stevor sequences. Electrophoretic mobility shift assays with DNA were carried out to verify Pf-Int/DNA binding. Finally, Pf-Int knock-out parasites were created in order to investigate the biological role of Pf-Int.Our data identify for the first time a malaria parasite gene with structural and functional features of recombinases. Pf-Int may bind to and alter DNA, either in a sequence specific or in a non-specific fashion, and may contribute to programmed or random DNA rearrangements. Pf-Int is the first molecular player identified with a potential role in genome plasticity in this pathogen. Finally, Pf-Int knock-out parasite is viable showing no detectable impact on blood stage development, which is compatible with such function.

  13. New L-Serine Derivative Ligands as Cocatalysts for Diels-Alder Reaction

    Science.gov (United States)

    Sousa, Carlos A. D.; Rodríguez-Borges, José E.; Freire, Cristina

    2013-01-01

    New L-serine derivative ligands were prepared and tested as cocatalyst in the Diels-Alder reactions between cyclopentadiene (CPD) and methyl acrylate, in the presence of several Lewis acids. The catalytic potential of the in situ formed complexes was evaluated based on the reaction yield. Bidentate serine ligands showed good ability to coordinate medium strength Lewis acids, thus boosting their catalytic activity. The synthesis of the L-serine ligands proved to be highly efficient and straightforward. PMID:24383009

  14. Cerebrospinal fluid D-serine concentrations in major depressive disorder negatively correlate with depression severity.

    Science.gov (United States)

    Ishiwata, Sayuri; Hattori, Kotaro; Sasayama, Daimei; Teraishi, Toshiya; Miyakawa, Tomoko; Yokota, Yuuki; Matsumura, Ryo; Nishikawa, Toru; Kunugi, Hiroshi

    2018-01-15

    D-serine is an endogenous co-agonist of N-methyl-D-aspartate receptor (NMDAR) and plays an important role in glutamate neurotransmission. Several studies suggested the possible involvement of D-serine related in the pathophysiology of psychiatric disorders including major depression disorders (MDD). We tried to examine whether cerebrospinal fluid (CSF) or plasma D-serine concentrations are altered in MDD and whether D-serine concentrations correlated with disease severity. 26 MDD patients and 27 healthy controls matched for age, sex and ethnicity were enrolled. We measured amino acids in these samples using by high-performance liquid chromatography with fluorometric detection. D-serine and L-serine, precursor of D-serine, levels in CSF or plasma were not significantly different in patients of MDD compared to controls. Furthermore, a significant correlation between D-serine levels in CSF and Hamilton Depression Rating Scale (HAMD)-17 score was observed (r = -0.65, p = 0.006). Furthermore, we found a positive correlation between CSF D-serine and HVA concentrations in MDD patients (r = 0.54, p = 0.007). CSF D-serine concentrations were correlated with those of plasma in MDD (r = 0.61, p = 0.01) but not in controls. In CSF, we also confirmed a significant correlation between D-serine and L-serine levels in MDD (r = 0.72, p depression severity and HVA concentrations and further investigation were required to reveal the effect of medication and disease heterogeneity. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Plasmodium falciparum secretome in erythrocyte and beyond

    Directory of Open Access Journals (Sweden)

    Rani eSoni

    2016-02-01

    Full Text Available Plasmodium falciparum is the causative agent of deadly malaria disease. It is an intracellular eukaryote and completes its multi-stage life cycle spanning the two hosts viz, mosquito and human. In order to habituate within host environment, parasite conform several strategies to evade host immune responses such as surface antigen polymorphism or modulation of host immune system and it is mediated by secretion of proteins from parasite to the host erythrocyte and beyond, collectively known as, malaria secretome. In this review, we will discuss about the deployment of parasitic secretory protein in mechanism implicated for immune evasion, protein trafficking, providing virulence, changing permeability and cyto-adherence of infected erythrocyte. We will be covering the possibilities of developing malaria secretome as a drug/vaccine target. This gathered information will be worthwhile in depicting a well-organized picture for host-pathogen interplay during the malaria infection and may also provide some clues for development of novel anti-malarial therapies.

  16. Dibenzylideneacetone analogues as novel Plasmodium falciparum inhibitors.

    Science.gov (United States)

    Aher, Rahul Balasaheb; Wanare, Gajanan; Kawathekar, Neha; Kumar, Ravi Ranjan; Kaushik, Naveen Kumar; Sahal, Dinkar; Chauhan, Virander Singh

    2011-05-15

    A series of dibenzylideneacetones (A1-A12) and some of their pyrazolines (B1-B4) were synthesized and evaluated in vitro for blood stage antiplasmodial properties in Plasmodium falciparum culture using SYBR-green-I fluorescence assay. The compound (1E, 4E)-1,5-bis(3,4-dimethoxyphenyl)penta-1,4-dien-3-one (A9) was found to be the most active with IC(50) of 1.97 μM against chloroquine-sensitive strain (3D7) and 1.69 μM against chloroquine-resistant field isolate (RKL9). The MTT based cytotoxicity assay on HeLa cell line has confirmed that A9 is selective in its action against malaria parasite (with a therapeutic index of 166). Our results revealed that these compounds exhibited promising antiplasmodial activities which can be further explored as potential leads for the development of cheaper, safe, effective and potent drugs against chloroquine-resistant malarial parasites. Copyright © 2011. Published by Elsevier Ltd.

  17. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  18. [1-14C]Glycolate metabolism and serine biosynthesis in soybean plants

    International Nuclear Information System (INIS)

    Calmes, J.; Viala, G.; Latche, J.C.; Cavalie, G.

    1977-01-01

    [1- 14 C]Glycolate metabolism was examined in leafy shoots of soybean plants (Glycine max (L.) Merr., var. Adepta). Only small amounts of 14 C were incorporated into evolved carbon dioxide and glucidic compounds. Free and protein glycine was labelled but higher levels of radioactivity were found in free serine. Changes in the distribution of 14 C with time showed that metabolic conversion glycollate → glycine → serine occurred very early and serine biosynthesis was more important in the shoot than in the leaves. Carbon dioxide labelling was always slight compared to serine labelling. These data suggest strong relations between glycollate and nitrogen metabolism

  19. Heterogeneity of D-Serine Distribution in the Human Central Nervous System

    Science.gov (United States)

    Suzuki, Masataka; Imanishi, Nobuaki; Mita, Masashi; Hamase, Kenji; Aiso, Sadakazu

    2017-01-01

    D-serine is an endogenous ligand for N-methyl-D-aspartate glutamate receptors. Accumulating evidence including genetic associations of D-serine metabolism with neurological or psychiatric diseases suggest that D-serine is crucial in human neurophysiology. However, distribution and regulation of D-serine in humans are not well understood. Here, we found that D-serine is heterogeneously distributed in the human central nervous system (CNS). The cerebrum contains the highest level of D-serine among the areas in the CNS. There is heterogeneity in its distribution in the cerebrum and even within the cerebral neocortex. The neocortical heterogeneity is associated with Brodmann or functional areas but is unrelated to basic patterns of cortical layer structure or regional expressional variation of metabolic enzymes for D-serine. Such D-serine distribution may reflect functional diversity of glutamatergic neurons in the human CNS, which may serve as a basis for clinical and pharmacological studies on D-serine modulation. PMID:28604057

  20. Sharing of antigens between Plasmodium falciparum and Anopheles albimanus Antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus

    Directory of Open Access Journals (Sweden)

    Albina Wide

    2006-12-01

    Full Text Available The presence of common antigens between Plasmodium falciparum and Anopheles albimanus was demonstrated. Different groups of rabbits were immunized with: crude extract from female An. albimanus (EAaF, red blood cells infected with Plasmodium falciparum (EPfs, and the SPf66 synthetic malaria vaccine. The rabbit's polyclonal antibodies were evaluated by ELISA, Multiple Antigen Blot Assay (MABA, and immunoblotting. All extracts were immunogenic in rabbits according to these three techniques, when they were evaluated against the homologous antigens. Ten molecules were identified in female mosquitoes and also in P. falciparum antigens by the autologous sera. The electrophoretic pattern by SDS-PAGE was different for the three antigens evaluated. Cross-reactions between An. albimanus and P. falciparum were found by ELISA, MABA, and immunoblotting. Anti-P. falciparum and anti-SPf66 antibodies recognized ten and five components in the EAaF crude extract, respectively. Likewise, immune sera against female An. albimanus identified four molecules in the P. falciparum extract antigen. As far as we know, this is the first work that demonstrates shared antigens between anophelines and malaria parasites. This finding could be useful for diagnosis, vaccines, and the study of physiology of the immune response to malaria.Epítopes de antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus fueron identificados. Diferentes grupos de conejos fueron inmunizados con: extracto crudo de mosquito hembra de An. albimanus (EAaH, glóbulos rojos infectados con P. falciparum (EPfs y la vacuna antimalárica sintética SPf66. Los anticuerpos policlonales producidos en conejos fueron evaluados por ELISA, inmunoensayo simultáneo de múltiples antígenos (MABA e Immunoblotting. Todos los extractos resultaron inmunogénicos cuando se evaluaron por ELISA, MABA e Immunoblotting. Diez moléculas fueron identificadas en los mosquitos hembras y diez en los antígenos de

  1. A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates

    KAUST Repository

    Subudhi, Amit

    2016-07-20

    Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic\\'s Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.

  2. A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates

    KAUST Repository

    Subudhi, Amit; Boopathi, P.A.; Middha, Sheetal; Acharya, Jyoti; Rao, Sudha Narayana; Mugasimangalam, Raja C.; Sirohi, Paramendra; Kochar, Sanjay K.; Kochar, Dhanpat K.; Das, Ashis

    2016-01-01

    Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic's Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.

  3. Random mutagenesis of human serine racemase reveals residues important for the enzymatic activity

    Czech Academy of Sciences Publication Activity Database

    Hoffman, Hillary Elizabeth; Jirásková, Jana; Zvelebil, M.; Konvalinka, Jan

    2010-01-01

    Roč. 75, č. 1 (2010), s. 59-79 ISSN 0010-0765 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : D-serine * serine racemase * random mutagenesis Subject RIV: CE - Biochemistry Impact factor: 0.853, year: 2010

  4. Amperometric Self-Referencing Ceramic Based Microelectrode Arrays for D-Serine Detection.

    Science.gov (United States)

    Campos-Beltrán, Diana; Konradsson-Geuken, Åsa; Quintero, Jorge E; Marshall, Lisa

    2018-03-06

    D-serine is the major D-amino acid in the mammalian central nervous system. As the dominant co-agonist of the endogenous synaptic NMDA receptor, D-serine plays a role in synaptic plasticity, learning, and memory. Alterations in D-serine are linked to neuropsychiatric disorders including schizophrenia. Thus, it is of increasing interest to monitor the concentration of D-serine in vivo as a relevant player in dynamic neuron-glia network activity. Here we present a procedure for amperometric detection of D-serine with self-referencing ceramic-based microelectrode arrays (MEAs) coated with D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO). We demonstrate in vitro D-serine recordings with a mean sensitivity of 8.61 ± 0.83 pA/µM to D-serine, a limit of detection (LOD) of 0.17 ± 0.01 µM, and a selectivity ratio of 80:1 or greater for D-serine over ascorbic acid (mean ± SEM; n = 12) that can be used for freely moving studies.

  5. Interleukin-10 regulates hepcidin in Plasmodium falciparum malaria

    KAUST Repository

    Huang, Honglei

    2014-02-10

    Background: Acute malarial anemia remains a major public health problem. Hepcidin, the major hormone controlling the availability of iron, is raised during acute and asymptomatic parasitemia. Understanding the role and mechanism of raised hepcidin and so reduced iron availability during infection is critical to establish evidence-based guidelines for management of malaria anemia. Our recent clinical evidence suggests a potential role of IL-10 in the regulation of hepcidin in patients with acute P. falciparum malaria. Methods: We have measured secretion of hepcidin by primary macrophages and the hepatoma cell line HepG2 stimulated with IL-10, IL-6 and Plasmodium falciparum-infected erythrocytes. Findings: We have observed that IL-10 and IL-6 production increased in primary macrophages when these cells were co-cultured with Plasmodium falciparum-infected erythrocytes. We found that IL-10 induced hepcidin secretion in primary macrophages in a dose-dependent manner but not in HepG2 cells. These effects were mediated through signal transducer and activator of transcription (STAT) 3-phosphorylation and completely abrogated by a specific STAT3 inhibitor. Conclusion: IL-10 can directly regulate hepcidin in primary macrophages but not in HepG2 cells. This effect can be modulated by Plasmodium falciparum. The results are consistent with a role for IL-10 in modulating iron metabolism during acute phase of infection. 2014 Huang et al.

  6. Variation of nitric oxide levels in imported Plasmodium falciparum ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... ISSN 1684–5315 © 2008 Academic Journals. Full Length Research Paper. Variation of nitric oxide levels in imported Plasmodium falciparum malaria episodes. De Sousa, Karina*, Silva, Marcelo S. and Tavira, Luís T. Instituto de Higiene e Medicina Tropical, Centro de Malária e outras Doenças Tropicais, ...

  7. More than just immune evasion: Hijacking complement by Plasmodium falciparum.

    Science.gov (United States)

    Schmidt, Christoph Q; Kennedy, Alexander T; Tham, Wai-Hong

    2015-09-01

    Malaria remains one of the world's deadliest diseases. Plasmodium falciparum is responsible for the most severe and lethal form of human malaria. P. falciparum's life cycle involves two obligate hosts: human and mosquito. From initial entry into these hosts, malaria parasites face the onslaught of the first line of host defence, the complement system. In this review, we discuss the complex interaction between complement and malaria infection in terms of hosts immune responses, parasite survival and pathogenesis of severe forms of malaria. We will focus on the role of complement receptor 1 and its associated polymorphisms in malaria immune complex clearance, as a mediator of parasite rosetting and as an entry receptor for P. falciparum invasion. Complement evasion strategies of P. falciparum parasites will also be highlighted. The sexual forms of the malaria parasites recruit the soluble human complement regulator Factor H to evade complement-mediated killing within the mosquito host. A novel evasion strategy is the deployment of parasite organelles to divert complement attack from infective blood stage parasites. Finally we outline the future challenge to understand the implications of these exploitation mechanisms in the interplay between successful infection of the host and pathogenesis observed in severe malaria. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Positive blood culture with Plasmodium falciparum : Case report

    NARCIS (Netherlands)

    De Vries, Jutte J. C.; Van Assen, Sander; Mulder, André B.; Kampinga, Greetje A.

    2007-01-01

    An adult traveler presented with fever and malaise after returning from Sierra Leone. Young trophozoites of Plasmodium falciparum were seen in a blood smear, with parasitemia being 10%. Moreover, blood cultures drawn on admission signaled as "positive" after 1 day of incubation, but no bacteria were

  9. Origin of the human malaria parasite Plasmodium falciparum in gorillas.

    Science.gov (United States)

    Liu, Weimin; Li, Yingying; Learn, Gerald H; Rudicell, Rebecca S; Robertson, Joel D; Keele, Brandon F; Ndjango, Jean-Bosco N; Sanz, Crickette M; Morgan, David B; Locatelli, Sabrina; Gonder, Mary K; Kranzusch, Philip J; Walsh, Peter D; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V; Muller, Martin N; Shaw, George M; Peeters, Martine; Sharp, Paul M; Rayner, Julian C; Hahn, Beatrice H

    2010-09-23

    Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here we develop a single-genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in faecal samples from wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed and almost always made up of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas comprised parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla origin and not of chimpanzee, bonobo or ancient human origin.

  10. Plasmodium falciparum transcriptome analysis reveals pregnancy malaria associated gene expression

    DEFF Research Database (Denmark)

    Tuikue Ndam, Nicaise; Bischoff, Emmanuel; Proux, Caroline

    2008-01-01

    BACKGROUND: Pregnancy-associated malaria (PAM) causing maternal anemia and low birth weight is among the multiple manifestations of Plasmodium falciparum malaria. Infected erythrocytes (iEs) can acquire various adhesive properties that mediate the clinical severity of malaria. Recent advances...

  11. Unusual Transmission of Plasmodium falciparum, Bordeaux, France, 2009

    Science.gov (United States)

    Vareil, Marc-Olivier; Tandonnet, Olivier; Chemoul, Audrey; Bogreau, Hervé; Saint-Léger, Mélanie; Micheau, Maguy; Millet, Pascal; Koeck, Jean-Louis; Boyer, Alexandre; Rogier, Christophe

    2011-01-01

    Plasmodium falciparum malaria is usually transmitted by mosquitoes. We report 2 cases in France transmitted by other modes: occupational blood exposure and blood transfusion. Even where malaria is not endemic, it should be considered as a cause of unexplained acute fever. PMID:21291597

  12. Inactivation of Plasmodium falciparum in whole body by riboflavin ...

    African Journals Online (AJOL)

    Background Malaria parasites are frequently trans- mitted by unscreened blood transfusions in Africa. Pathogen reduction methods in whole blood would thus greatly improve blood safety. We aimed to determine the efficacy of riboflavin plus irradiation for treatment of whole blood infected with Plasmodium falciparum.

  13. Dhfr and dhps mutations in Plasmodium falciparum isolates in ...

    African Journals Online (AJOL)

    Sulfadoxine-pyrimethamine (SP), the current first line antimalarial drug in Tanzania, is compromised by evolution and spread of mutations in the parasite's dhfr and dhps genes. In the present study we established the baseline frequencies of Plasmodium falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate ...

  14. Blood monocyte oxidative burst activity in acute P. falciparum malaria

    DEFF Research Database (Denmark)

    Nielsen, H; Theander, T G

    1989-01-01

    The release of superoxide anion from blood monocytes was studied in eight patients with acute primary attack P. falciparum malaria. Before treatment a significant enhancement of the oxidative burst prevailed, which contrasts with previous findings of a depressed monocyte chemotactic responsiveness...

  15. Plasmodium falciparum uses vitamin E to avoid oxidative stress.

    Science.gov (United States)

    Sussmann, Rodrigo A C; Fotoran, Wesley L; Kimura, Emilia A; Katzin, Alejandro M

    2017-10-10

    Plasmodium falciparum is sensitive to oxidative stress in vitro and in vivo, and many drugs such as artemisinin, chloroquine and cercosporin interfere in the parasite's redox system. To minimize the damage caused by reactive radicals, antioxidant enzymes and their substrates found in parasites and in erythrocytes must be functionally active. It was shown that P. falciparum synthesizes vitamin E and that usnic acid acts as an inhibitor of its biosynthesis. Vitamin E is a potent antioxidant that protects polyunsaturated fatty acids from lipid peroxidation, and this activity can be measured by detecting its oxidized product and by evaluating reactive oxygen species (ROS) levels. Here, we demonstrated that ROS levels increased in P. falciparum when vitamin E biosynthesis was inhibited by usnic acid treatment and decreased to basal levels if exogenous vitamin E was added. Furthermore, we used metabolic labelling to demonstrate that vitamin E biosynthesized by the parasite acts as an antioxidant since we could detect its radiolabeled oxidized product. The treatment with chloroquine or cercosporin of the parasites increased the ratio between α-tocopherolquinone and α-tocopherol. Our findings demonstrate that vitamin E produced endogenously by P. falciparum is active as an antioxidant, probably protecting the parasite from the radicals generated by drugs.

  16. Population genomics diversity of Plasmodium falciparum in malaria ...

    African Journals Online (AJOL)

    Background: Plasmodium falciparum, the most dangerous malaria parasite species to ... tigen for subunit malaria vaccine.10 It comprises highly ... were also prepared for Giemsa staining as described by ... parasites with different alleles at a given locus and ranges ..... surface protein 1, immune evasion and vaccines against.

  17. Fine-scale genetic characterization of Plasmodium falciparum

    Indian Academy of Sciences (India)

    We have initiated such a study and presented herewith the results from the in silico understanding of a seventh chromosomal region of the malarial parasite Plasmodium falciparum encompassing the antigenic var genes (coding pfemp1) and the drug-resistant gene pfcrt located at a specified region of the chromosome 7.

  18. Submicroscopic Plasmodium falciparum infections in pregnancy in Ghana

    NARCIS (Netherlands)

    Mockenhaupt, F. P.; Rong, B.; Till, H.; Eggelte, T. A.; Beck, S.; Gyasi-Sarpong, C.; Thompson, W. N.; Bienzle, U.

    2000-01-01

    Malarial parasitaemia below the threshold of microscopy but detectable by polymerase chain reaction (PCR) assays is common in endemic regions. This study was conducted to examine prevalence, predictors, and effects of submicroscopic Plasmodium falciparum infections in pregnancy. In a cross-sectional

  19. High prevalence of Plasmodium falciparum malaria among Human ...

    African Journals Online (AJOL)

    Malaria and Human Immunodeficiency Virus (HIV) infections are major public health problems in Sub-Saharan Africa. Their overlapping geographical distribution and co-existence often result into high morbidity and mortality. This study was designed to establish the prevalence of Plasmodium falciparum malaria among HIV ...

  20. Plasmodium falciparum multiplicity correlates with anaemia in symptomatic malaria

    NARCIS (Netherlands)

    Mockenhaupt, Frank P.; Ehrhardt, Stephan; Eggelte, Teunis A.; Markert, Miriam; Anemana, Sylvester; Otchwemah, Rowland; Bienzle, Ulrich

    2003-01-01

    In 366 Ghanaian children with symptomatic Plasmodium falciparum malaria, low haemoglobin levels and severe anaemia were associated with a high multiplicity of infection (MOI) and with distinct merozoite surface protein alleles. High MOI not only reflects premunition but may also contribute to

  1. L-Serine overproduction with minimization of by-product synthesis by engineered Corynebacterium glutamicum.

    Science.gov (United States)

    Zhu, Qinjian; Zhang, Xiaomei; Luo, Yuchang; Guo, Wen; Xu, Guoqiang; Shi, Jinsong; Xu, Zhenghong

    2015-02-01

    The direct fermentative production of L-serine by Corynebacterium glutamicum from sugars is attractive. However, superfluous by-product accumulation and low L-serine productivity limit its industrial production on large scale. This study aimed to investigate metabolic and bioprocess engineering strategies towards eliminating by-products as well as increasing L-serine productivity. Deletion of alaT and avtA encoding the transaminases and introduction of an attenuated mutant of acetohydroxyacid synthase (AHAS) increased both L-serine production level (26.23 g/L) and its productivity (0.27 g/L/h). Compared to the parent strain, the by-products L-alanine and L-valine accumulation in the resulting strain were reduced by 87 % (from 9.80 to 1.23 g/L) and 60 % (from 6.54 to 2.63 g/L), respectively. The modification decreased the metabolic flow towards the branched-chain amino acids (BCAAs) and induced to shift it towards L-serine production. Meanwhile, it was found that corn steep liquor (CSL) could stimulate cell growth and increase sucrose consumption rate as well as L-serine productivity. With addition of 2 g/L CSL, the resulting strain showed a significant improvement in the sucrose consumption rate (72 %) and the L-serine productivity (67 %). In fed-batch fermentation, 42.62 g/L of L-serine accumulation was achieved with a productivity of 0.44 g/L/h and yield of 0.21 g/g sucrose, which was the highest production of L-serine from sugars to date. The results demonstrated that combined metabolic and bioprocess engineering strategies could minimize by-product accumulation and improve L-serine productivity.

  2. In silico discovery of transcription regulatory elements in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Le Roch Karine G

    2008-02-01

    Full Text Available Abstract Background With the sequence of the Plasmodium falciparum genome and several global mRNA and protein life cycle expression profiling projects now completed, elucidating the underlying networks of transcriptional control important for the progression of the parasite life cycle is highly pertinent to the development of new anti-malarials. To date, relatively little is known regarding the specific mechanisms the parasite employs to regulate gene expression at the mRNA level, with studies of the P. falciparum genome sequence having revealed few cis-regulatory elements and associated transcription factors. Although it is possible the parasite may evoke mechanisms of transcriptional control drastically different from those used by other eukaryotic organisms, the extreme AT-rich nature of P. falciparum intergenic regions (~90% AT presents significant challenges to in silico cis-regulatory element discovery. Results We have developed an algorithm called Gene Enrichment Motif Searching (GEMS that uses a hypergeometric-based scoring function and a position-weight matrix optimization routine to identify with high-confidence regulatory elements in the nucleotide-biased and repeat sequence-rich P. falciparum genome. When applied to promoter regions of genes contained within 21 co-expression gene clusters generated from P. falciparum life cycle microarray data using the semi-supervised clustering algorithm Ontology-based Pattern Identification, GEMS identified 34 putative cis-regulatory elements associated with a variety of parasite processes including sexual development, cell invasion, antigenic variation and protein biosynthesis. Among these candidates were novel motifs, as well as many of the elements for which biological experimental evidence already exists in the Plasmodium literature. To provide evidence for the biological relevance of a cell invasion-related element predicted by GEMS, reporter gene and electrophoretic mobility shift assays

  3. From malaria parasite point of view – Plasmodium falciparum evolution

    Directory of Open Access Journals (Sweden)

    Agata Zerka

    2015-12-01

    Full Text Available Malaria is caused by infection with protozoan parasites belonging to the genus Plasmodium, which have arguably exerted the greatest selection pressure on humans in the history of our species. Besides humans, different Plasmodium parasites infect a wide range of animal hosts, from marine invertebrates to primates. On the other hand, individual Plasmodium species show high host specificity. The extraordinary evolution of Plasmodium probably began when a free-living red algae turned parasitic, and culminated with its ability to thrive inside a human red blood cell. Studies on the African apes generated new data on the evolution of malaria parasites in general and the deadliest human-specific species, Plasmodium falciparum, in particular. Initially, it was hypothesized that P. falciparum descended from the chimpanzee malaria parasite P. reichenowi, after the human and the chimp lineage diverged about 6 million years ago. However, a recently identified new species infecting gorillas, unexpectedly showed similarity to P. falciparum and was therefore named P. praefalciparum. That finding spurred an alternative hypothesis, which proposes that P. falciparum descended from its gorilla rather than chimp counterpart. In addition, the gorilla-to-human host shift may have occurred more recently (about 10 thousand years ago than the theoretical P. falciparum-P. reichenowi split. One of the key aims of the studies on Plasmodium evolution is to elucidate the mechanisms that allow the incessant host shifting and retaining the host specificity, especially in the case of human-specific species. Thorough understanding of these phenomena will be necessary to design effective malaria treatment and prevention strategies.

  4. Production of recombinant proteins from Plasmodium falciparum in Escherichia coli.

    Science.gov (United States)

    Guerra, Ángela Patricia; Calvo, Eliana Patricia; Wasserman, Moisés; Chaparro-Olaya, Jacqueline

    2016-02-23

    The production of recombinant proteins is essential for the characterization and functional study of proteins from Plasmodium falciparum. However, the proteins of P. falciparum are among the most challenging to express, and when expression is achieved, the recombinant proteins usually fold incorrectly and lead to the formation of inclusion bodies.  To obtain and purify four recombinant proteins and to use them as antigens to produce polyclonal antibodies. The production efficiency and solubility were evaluated as the proteins were expressed in two genetically modified strains of Escherichia coli to favor the production of heterologous proteins (BL21-CodonPlus (DE3)-RIL and BL21-pG-KJE8).  The four recombinant P. falciparum proteins corresponding to partial sequences of PfMyoA (Myosin A) and PfGAP50 (gliding associated protein 50), and the complete sequences of PfMTIP (myosin tail interacting protein) and PfGAP45 (gliding associated protein 45), were produced as glutathione S-transferase-fusion proteins, purified and used for immunizing mice.  The protein expression was much more efficient in BL21-CodonPlus, the strain that contains tRNAs that are rare in wild-type E. coli, compared to the expression in BL21-pG-KJE8. In spite of the fact that BL21-pG-KJE8 overexpresses chaperones, this strain did not minimize the formation of inclusion bodies.  The use of genetically modified strains of E. coli was essential to achieve high expression levels of the four evaluated P. falciparum proteins and lead to improved solubility of two of them. The approach used here allowed us to obtain and purify four P. falciparum proteins in enough quantity to produce polyclonal antibodies in mice, and a fair amount of two pure and soluble recombinant proteins for future assays.

  5. Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal.

    Science.gov (United States)

    Sylla, Khadime; Tine, Roger Clément Kouly; Ndiaye, Magatte; Sow, Doudou; Sarr, Aïssatou; Mbuyi, Marie Louise Tshibola; Diouf, Ibrahima; Lô, Amy Colé; Abiola, Annie; Seck, Mame Cheikh; Ndiaye, Mouhamadou; Badiane, Aïda Sadikh; N'Diaye, Jean Louis A; Ndiaye, Daouda; Faye, Oumar; Dieng, Thérèse; Dieng, Yémou; Ndir, Oumar; Gaye, Oumar; Faye, Babacar

    2015-07-16

    In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate

  6. The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Zbynek Bozdech

    2003-10-01

    Full Text Available Plasmodium falciparum is the causative agent of the most burdensome form of human malaria, affecting 200-300 million individuals per year worldwide. The recently sequenced genome of P. falciparum revealed over 5,400 genes, of which 60% encode proteins of unknown function. Insights into the biochemical function and regulation of these genes will provide the foundation for future drug and vaccine development efforts toward eradication of this disease. By analyzing the complete asexual intraerythrocytic developmental cycle (IDC transcriptome of the HB3 strain of P. falciparum, we demonstrate that at least 60% of the genome is transcriptionally active during this stage. Our data demonstrate that this parasite has evolved an extremely specialized mode of transcriptional regulation that produces a continuous cascade of gene expression, beginning with genes corresponding to general cellular processes, such as protein synthesis, and ending with Plasmodium-specific functionalities, such as genes involved in erythrocyte invasion. The data reveal that genes contiguous along the chromosomes are rarely coregulated, while transcription from the plastid genome is highly coregulated and likely polycistronic. Comparative genomic hybridization between HB3 and the reference genome strain (3D7 was used to distinguish between genes not expressed during the IDC and genes not detected because of possible sequence variations. Genomic differences between these strains were found almost exclusively in the highly antigenic subtelomeric regions of chromosomes. The simple cascade of gene regulation that directs the asexual development of P. falciparum is unprecedented in eukaryotic biology. The transcriptome of the IDC resembles a "just-in-time" manufacturing process whereby induction of any given gene occurs once per cycle and only at a time when it is required. These data provide to our knowledge the first comprehensive view of the timing of transcription throughout the

  7. Interaction of an atypical Plasmodium falciparum ETRAMP with human apolipoproteins

    Directory of Open Access Journals (Sweden)

    Sahasrabudhe Sudhir

    2008-10-01

    Full Text Available Abstract Background In order to establish a successful infection in the human host, the malaria parasite Plasmodium falciparum must establish interactions with a variety of human proteins on the surface of different cell types, as well as with proteins inside the host cells. To better understand this aspect of malaria pathogenesis, a study was conducted with the goal of identifying interactions between proteins of the parasite and those of its human host. Methods A modified yeast two-hybrid methodology that preferentially selects protein fragments that can be expressed in yeast was used to conduct high-throughput screens with P. falciparum protein fragments against human liver and cerebellum libraries. The resulting dataset was analyzed to exclude interactions that are not likely to occur in the human host during infection. Results An initial set of 2,200 interactions was curated to remove proteins that are unlikely to play a role in pathogenesis based on their annotation or localization, and proteins that behave promiscuously in the two-hybrid assay, resulting in a final dataset of 456 interactions. A cluster that implicates binding between P. falciparum PFE1590w/ETRAMP5, a putative parasitophorous vacuole membrane protein, and human apolipoproteins ApoA, ApoB and ApoE was selected for further analysis. Different isoforms of ApoE, which are associated with different outcomes of malaria infection, were shown to display differential interactions with PFE1590w. Conclusion A dataset of interactions between proteins of P. falciparum and those of its human host was generated. The preferential interaction of the P. falciparum PFE1590w protein with the human ApoE ε3 and ApoE ε4 isoforms, but not the ApoE ε2 isoform, supports the hypothesis that ApoE genotype affects risk of malaria infection. The dataset contains other interactions of potential relevance to disease that may identify possible vaccine candidates and drug targets.

  8. Immunoglobulin G antibody reactivity to a group A Plasmodium falciparum erythrocyte membrane protein 1 and protection from P. falciparum malaria

    DEFF Research Database (Denmark)

    Magistrado, Pamela A; Lusingu, John; Vestergaard, Lasse S

    2007-01-01

    where P. falciparum is endemic, parasites causing severe malaria and malaria in young children with limited immunity tend to express semiconserved PfEMP1 molecules encoded by group A var genes. Here we investigated antibody responses of Tanzanians who were 0 to 19 years old to PF11_0008, a group A Pf...

  9. Serine integrase chimeras with activity in E. coli and HeLa cells

    Directory of Open Access Journals (Sweden)

    Alfonso P. Farruggio

    2014-09-01

    Full Text Available In recent years, application of serine integrases for genomic engineering has increased in popularity. The factor-independence and unidirectionality of these large serine recombinases makes them well suited for reactions such as site-directed vector integration and cassette exchange in a wide variety of organisms. In order to generate information that might be useful for altering the specificity of serine integrases and to improve their efficiency, we tested a hybridization strategy that has been successful with several small serine recombinases. We created chimeras derived from three characterized members of the serine integrase family, phiC31, phiBT1, and TG1 integrases, by joining their amino- and carboxy-terminal portions. We found that several phiBT1-phiC31 (BC and phiC31-TG1 (CT hybrid integrases are active in E. coli. BC chimeras function on native att-sites and on att-sites that are hybrids between those of the two donor enzymes, while CT chimeras only act on the latter att-sites. A BC hybrid, BC{−1}, was also active in human HeLa cells. Our work is the first to demonstrate chimeric serine integrase activity. This analysis sheds light on integrase structure and function, and establishes a potentially tractable means to probe the specificity of the thousands of putative large serine recombinases that have been revealed by bioinformatics studies.

  10. Crystal Structure of Serine Racemase that Produces Neurotransmitter font-variant:small-caps">d-Serine for Stimulation of the NMDA Receptor

    Science.gov (United States)

    Goto, Masaru

    font-variant:small-caps">d-Serine is an endogenous coagonist for the N-methyl-font-variant:small-caps">d-aspartate receptor and is involved in excitatory neurotransmission in the brain. Mammalian pyridoxal 5’-phosphate-dependent serine racemase, which is localized in the mammalian brain, catalyzes the racemization of font-variant:small-caps">l-serine to yield font-variant:small-caps">d-serine and vice versa. We have determined the structures of three forms of the mammalian enzyme homolog from Schizosaccharomyces pombe. Lys57 and Ser82 located on the protein and solvent sides, respectively, with respect to the cofactor plane, are acid-base catalysts that shuttle protons to the substrate. The modified enzyme, which has a unique lysino-font-variant:small-caps">d-alanyl residue at the active site, also binds the substrate serine in the active site, suggesting that the lysino-font-variant:small-caps">d-alanyl residue acts as a catalytic base in the same manner as Lys57 of the wild type enzyme.

  11. Highly sensitive solid-phase radioimmunoassay for the assay of Plasmodium falciparum antigens and antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Avraham, H.; Golenser, J.; Gazitt, Y.; Spira, D.T.; Sulitzeanu, D. (Hebrew Univ., Jerusalem (Israel). Hadassah Medical School)

    1982-08-27

    A highly sensitive radioimmunoassay for detection of P. falciparum antibodies and antigens is described. A partially purified P. falciparum antigen preparation is obtained from in vitro cultured parasites enriched after gelatin sedimentation by sonicating the infected red blood cells and precipitating the proteins with 50% saturated ammonium sulfate. The precipitate is dissolved in buffer, ultracentrifuged and used to coat wells of microtiter plates. Anti-P. falciparum antibodies are detected by incubating antiserum dilutions in the coated wells and detecting the bound IgG with radioiodinated staphylococcal protein A. P. falciparum antigens are detected by their ability to inhibit binding of antibodies to the coated wells. Sera of individuals with a history of P. falciparum infection contain antibodies detectable at a dilution of 1:75,000. P. falciparum RBC infected in vitro can be detected at levels of parasitemia of the order of 1 parasite or less per 10/sup 6/ RBC.

  12. A highly sensitive solid-phase radioimmunoassay for the assay of Plasmodium falciparum antigens and antibodies

    International Nuclear Information System (INIS)

    Avraham, H.; Golenser, J.; Gazitt, Y.; Spira, D.T.; Sulitzeanu, D.

    1982-01-01

    A highly sensitive radioimmunoassay for detection of P. falciparum antibodies and antigens is described. A partially purified P. falciparum antigen preparation is obtained from in vitro cultured parasites enriched after gelatin sedimentation by sonicating the infected red blood cells and precipitating the proteins with 50% saturated ammonium sulfate. The precipitate is dissolved in buffer, ultracentrifuged and used to coat wells of microtiter plates. Anti-P. falciparum antibodies are detected by incubating antiserum dilutions in the coated wells and detecting the bound IgG with radioiodinated staphylococcal protein A. P. falciparum antigens are detected by their ability to inhibit binding of antibodies to the coated wells. Sera of individuals with a history of P. falciparum infection contain antibodies detectable at a dilution of 1:75,000. P. falciparum RBC infected in vitro can be detected at levels of parasitemia of the order of 1 parasite or less per 10 6 RBC. (Auth.)

  13. In vitro growth of Plasmodium falciparum in neonatal blood.

    Science.gov (United States)

    Sauerzopf, Ulrich; Honkpehedji, Yabo J; Adgenika, Ayôla A; Feugap, Elianne N; Ngoma, Ghyslain Mombo; Mackanga, Jean-Rodolphe; Lötsch, Felix; Loembe, Marguerite M; Kremsner, Peter G; Mordmüller, Benjamin; Ramharter, Michael

    2014-11-18

    Children below the age of six months suffer less often from malaria than older children in sub-Saharan Africa. This observation is commonly attributed to the persistence of foetal haemoglobin (HbF), which is considered not to permit growth of Plasmodium falciparum and therefore providing protection against malaria. Since this concept has recently been challenged, this study evaluated the effect of HbF erythrocytes and maternal plasma on in vitro parasite growth of P. falciparum in Central African Gabon. Umbilical cord blood and peripheral maternal blood were collected at delivery at the Albert Schweitzer Hospital in Gabon. Respective erythrocyte suspension and plasma were used in parallel for in vitro culture. In vitro growth rates were compared between cultures supplemented with either maternal or cord erythrocytes. Plasma of maternal blood and cord blood was evaluated. Parasite growth rates were assessed by the standard HRP2-assay evaluating the increase of HRP2 concentration in Plasmodium culture. Culture of P. falciparum using foetal erythrocytes led to comparable growth rates (mean growth rate = 4.2, 95% CI: 3.5 - 5.0) as cultures with maternal red blood cells (mean growth rate =4.2, 95% CI: 3.4 - 5.0) and those from non-malaria exposed individuals (mean growth rate = 4.6, 95% CI: 3.8 - 5.5). Standard in vitro culture of P. falciparum supplemented with either maternal or foetal plasma showed both significantly lower growth rates than a positive control using non-malaria exposed donor plasma. These data challenge the concept of HbF serving as intrinsic inhibitor of P. falciparum growth in the first months of life. Erythrocytes containing HbF are equally permissive to P. falciparum growth in vitro. However, addition of maternal and cord plasma led to reduced in vitro growth which may translate to protection against clinical disease or show synergistic effects with HbF in vivo. Further studies are needed to elucidate the pathophysiology of innate and acquired

  14. Plasmodium falciparum ookinete expression of plasmepsin VII and plasmepsin X.

    Science.gov (United States)

    Li, Fengwu; Bounkeua, Viengngeun; Pettersen, Kenneth; Vinetz, Joseph M

    2016-02-24

    Plasmodium invasion of the mosquito midgut is a population bottleneck in the parasite lifecycle. Interference with molecular mechanisms by which the ookinete invades the mosquito midgut is one potential approach to developing malaria transmission-blocking strategies. Plasmodium aspartic proteases are one such class of potential targets: plasmepsin IV (known to be present in the asexual stage food vacuole) was previously shown to be involved in Plasmodium gallinaceum infection of the mosquito midgut, and plasmepsins VII and plasmepsin X (not known to be present in the asexual stage food vacuole) are upregulated in Plasmodium falciparum mosquito stages. These (and other) parasite-derived enzymes that play essential roles during ookinete midgut invasion are prime candidates for transmission-blocking vaccines. Reverse transcriptase PCR (RT-PCR) was used to determine timing of P. falciparum plasmepsin VII (PfPM VII) and plasmepsin X (PfPM X) mRNA transcripts in parasite mosquito midgut stages. Protein expression was confirmed by western immunoblot and immunofluorescence assays (IFA) using anti-peptide monoclonal antibodies (mAbs) against immunogenic regions of PfPM VII and PfPM X. These antibodies were also used in standard membrane feeding assays (SMFA) to determine whether inhibition of these proteases would affect parasite transmission to mosquitoes. The Mann-Whitney U test was used to analyse mosquito transmission assay results. RT-PCR, western immunoblot and immunofluorescence assay confirmed expression of PfPM VII and PfPM X in mosquito stages. Whereas PfPM VII was expressed in zygotes and ookinetes, PfPM X was expressed in gametes, zygotes, and ookinetes. Antibodies against PfPM VII and PfPM X decreased P. falciparum invasion of the mosquito midgut when used at high concentrations, indicating that these proteases play a role in Plasmodium mosquito midgut invasion. Failure to generate genetic knockouts of these genes limited determination of the precise role of

  15. Antimalarial Activity of KAF156 in Falciparum and Vivax Malaria.

    Science.gov (United States)

    White, Nicholas J; Duong, Tran T; Uthaisin, Chirapong; Nosten, François; Phyo, Aung P; Hanboonkunupakarn, Borimas; Pukrittayakamee, Sasithon; Jittamala, Podjanee; Chuthasmit, Kittiphum; Cheung, Ming S; Feng, Yiyan; Li, Ruobing; Magnusson, Baldur; Sultan, Marc; Wieser, Daniela; Xun, Xiaolei; Zhao, Rong; Diagana, Thierry T; Pertel, Peter; Leong, F Joel

    2016-09-22

    KAF156 belongs to a new class of antimalarial agents (imidazolopiperazines), with activity against asexual and sexual blood stages and the preerythrocytic liver stages of malarial parasites. We conducted a phase 2, open-label, two-part study at five centers in Thailand and Vietnam to assess the antimalarial efficacy, safety, and pharmacokinetic profile of KAF156 in adults with acute Plasmodium vivax or P. falciparum malaria. Assessment of parasite clearance rates in cohorts of patients with vivax or falciparum malaria who were treated with multiple doses (400 mg once daily for 3 days) was followed by assessment of the cure rate at 28 days in a separate cohort of patients with falciparum malaria who received a single dose (800 mg). Median parasite clearance times were 45 hours (interquartile range, 42 to 48) in 10 patients with falciparum malaria and 24 hours (interquartile range, 20 to 30) in 10 patients with vivax malaria after treatment with the multiple-dose regimen and 49 hours (interquartile range, 42 to 54) in 21 patients with falciparum malaria after treatment with the single dose. Among the 21 patients who received the single dose and were followed for 28 days, 1 had reinfection and 7 had recrudescent infections (cure rate, 67%; 95% credible interval, 46 to 84). The mean (±SD) KAF156 terminal elimination half-life was 44.1±8.9 hours. There were no serious adverse events in this small study. The most common adverse events included sinus bradycardia, thrombocytopenia, hypokalemia, anemia, and hyperbilirubinemia. Vomiting of grade 2 or higher occurred in 2 patients, 1 of whom discontinued treatment because of repeated vomiting after receiving the single 800-mg dose. More adverse events were reported in the single-dose cohort, which had longer follow-up, than in the multiple-dose cohorts. KAF156 showed antimalarial activity without evident safety concerns in a small number of adults with uncomplicated P. vivax or P. falciparum malaria. (Funded by Novartis and

  16. Identification of O-GlcNAcylated proteins in Plasmodium falciparum.

    Science.gov (United States)

    Kupferschmid, Mattis; Aquino-Gil, Moyira Osny; Shams-Eldin, Hosam; Schmidt, Jörg; Yamakawa, Nao; Krzewinski, Frédéric; Schwarz, Ralph T; Lefebvre, Tony

    2017-11-29

    Post-translational modifications (PTMs) constitute a huge group of chemical modifications increasing the complexity of the proteomes of living beings. PTMs have been discussed as potential anti-malarial drug targets due to their involvement in many cell processes. O-GlcNAcylation is a widespread PTM found in different organisms including Plasmodium falciparum. The aim of this study was to identify O-GlcNAcylated proteins of P. falciparum, to learn more about the modification process and to understand its eventual functions in the Apicomplexans. The P. falciparum strain 3D7 was amplified in erythrocytes and purified. The proteome was checked for O-GlcNAcylation using different methods. The level of UDP-GlcNAc, the donor of the sugar moiety for O-GlcNAcylation processes, was measured using high-pH anion exchange chromatography. O-GlcNAcylated proteins were enriched and purified utilizing either click chemistry labelling or adsorption on succinyl-wheat germ agglutinin beads. Proteins were then identified by mass-spectrometry (nano-LC MS/MS). While low when compared to MRC5 control cells, P. falciparum disposes of its own pool of UDP-GlcNAc. By using proteomics methods, 13 O-GlcNAcylated proteins were unambiguously identified (11 by click-chemistry and 6 by sWGA-beads enrichment; 4 being identified by the 2 approaches) in late trophozoites. These proteins are all part of pathways, functions and structures important for the parasite survival. By probing clicked-proteins with specific antibodies, Hsp70 and α-tubulin were identified as P. falciparum O-GlcNAc-bearing proteins. This study is the first report on the identity of P. falciparum O-GlcNAcylated proteins. While the parasite O-GlcNAcome seems close to those of other species, the structural differences exhibited by the proteomes provides a glimpse of innovative therapeutic paths to fight malaria. Blocking biosynthesis of UDP-GlcNAc in the parasites is another promising option to reduce Plasmodium life cycle.

  17. A world malaria map: Plasmodium falciparum endemicity in 2007.

    Directory of Open Access Journals (Sweden)

    Simon I Hay

    2009-03-01

    Full Text Available Efficient allocation of resources to intervene against malaria requires a detailed understanding of the contemporary spatial distribution of malaria risk. It is exactly 40 y since the last global map of malaria endemicity was published. This paper describes the generation of a new world map of Plasmodium falciparum malaria endemicity for the year 2007.A total of 8,938 P. falciparum parasite rate (PfPR surveys were identified using a variety of exhaustive search strategies. Of these, 7,953 passed strict data fidelity tests for inclusion into a global database of PfPR data, age-standardized to 2-10 y for endemicity mapping. A model-based geostatistical procedure was used to create a continuous surface of malaria endemicity within previously defined stable spatial limits of P. falciparum transmission. These procedures were implemented within a Bayesian statistical framework so that the uncertainty of these predictions could be evaluated robustly. The uncertainty was expressed as the probability of predicting correctly one of three endemicity classes; previously stratified to be an informative guide for malaria control. Population at risk estimates, adjusted for the transmission modifying effects of urbanization in Africa, were then derived with reference to human population surfaces in 2007. Of the 1.38 billion people at risk of stable P. falciparum malaria, 0.69 billion were found in Central and South East Asia (CSE Asia, 0.66 billion in Africa, Yemen, and Saudi Arabia (Africa+, and 0.04 billion in the Americas. All those exposed to stable risk in the Americas were in the lowest endemicity class (PfPR2-10 5 to or = 40% areas. High endemicity was widespread in the Africa+ region, where 0.35 billion people are at this level of risk. Most of the rest live at intermediate risk (0.20 billion, with a smaller number (0.11 billion at low stable risk.High levels of P. falciparum malaria endemicity are common in Africa. Uniformly low endemic levels are

  18. A world malaria map: Plasmodium falciparum endemicity in 2007.

    Science.gov (United States)

    Hay, Simon I; Guerra, Carlos A; Gething, Peter W; Patil, Anand P; Tatem, Andrew J; Noor, Abdisalan M; Kabaria, Caroline W; Manh, Bui H; Elyazar, Iqbal R F; Brooker, Simon; Smith, David L; Moyeed, Rana A; Snow, Robert W

    2009-03-24

    Efficient allocation of resources to intervene against malaria requires a detailed understanding of the contemporary spatial distribution of malaria risk. It is exactly 40 y since the last global map of malaria endemicity was published. This paper describes the generation of a new world map of Plasmodium falciparum malaria endemicity for the year 2007. A total of 8,938 P. falciparum parasite rate (PfPR) surveys were identified using a variety of exhaustive search strategies. Of these, 7,953 passed strict data fidelity tests for inclusion into a global database of PfPR data, age-standardized to 2-10 y for endemicity mapping. A model-based geostatistical procedure was used to create a continuous surface of malaria endemicity within previously defined stable spatial limits of P. falciparum transmission. These procedures were implemented within a Bayesian statistical framework so that the uncertainty of these predictions could be evaluated robustly. The uncertainty was expressed as the probability of predicting correctly one of three endemicity classes; previously stratified to be an informative guide for malaria control. Population at risk estimates, adjusted for the transmission modifying effects of urbanization in Africa, were then derived with reference to human population surfaces in 2007. Of the 1.38 billion people at risk of stable P. falciparum malaria, 0.69 billion were found in Central and South East Asia (CSE Asia), 0.66 billion in Africa, Yemen, and Saudi Arabia (Africa+), and 0.04 billion in the Americas. All those exposed to stable risk in the Americas were in the lowest endemicity class (PfPR2-10 5 to or = 40%) areas. High endemicity was widespread in the Africa+ region, where 0.35 billion people are at this level of risk. Most of the rest live at intermediate risk (0.20 billion), with a smaller number (0.11 billion) at low stable risk. High levels of P. falciparum malaria endemicity are common in Africa. Uniformly low endemic levels are found in the

  19. MBL-associated serine proteases (MASPs) and infectious diseases.

    Science.gov (United States)

    Beltrame, Marcia H; Boldt, Angelica B W; Catarino, Sandra J; Mendes, Hellen C; Boschmann, Stefanie E; Goeldner, Isabela; Messias-Reason, Iara

    2015-09-01

    The lectin pathway of the complement system has a pivotal role in the defense against infectious organisms. After binding of mannan-binding lectin (MBL), ficolins or collectin 11 to carbohydrates or acetylated residues on pathogen surfaces, dimers of MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2) activate a proteolytic cascade, which culminates in the formation of the membrane attack complex and pathogen lysis. Alternative splicing of the pre-mRNA encoding MASP-1 results in two other products, MASP-3 and MAp44, which regulate activation of the cascade. A similar mechanism allows the gene encoding MASP-2 to produce the truncated MAp19 protein. Polymorphisms in MASP1 and MASP2 genes are associated with protein serum levels and functional activity. Since the first report of a MASP deficiency in 2003, deficiencies in lectin pathway proteins have been associated with recurrent infections and several polymorphisms were associated with the susceptibility or protection to infectious diseases. In this review, we summarize the findings on the role of MASP polymorphisms and serum levels in bacterial, viral and protozoan infectious diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Stromal serine protein kinase activity in spinach chloroplasts

    International Nuclear Information System (INIS)

    Cortez, N.; Lucero, H.A.; Vallejos, R.H.

    1987-01-01

    At least twelve 32 P-labeled stromal proteins were detected by electrophoresis under denaturing conditions when intact chloroplasts were incubated with 32 Pi, in the light but only three were detected in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or in the dark. Incubation of isolated stroma with [gamma- 32 P]ATP resulted in the preferential phosphorylation of one of them, a 70-kDa polypeptide, in serine residues. Thylakoid membranes in the dark promoted the phosphorylation of two additional stromal polypeptides of 55 and 40 kDa. Illumination during the phosphorylation of stroma in the presence of thylakoids stimulated severalfold the labeling of the 40-kDa polypeptide but not when DCMU was added. The protein kinase activity present in isolated stroma phosphorylated exogenous substrates like histone III, phosvitin, histone II, and casein with specific activities of 3, 1.8, 0.7, and 0.2 pmol X mg-1 X min-1. Histone III polypeptides were phosphorylated differently by stroma and by thylakoids in the dark. Moreover, histone III phosphorylated by thylakoids in the dark yielded a pattern of phosphopeptides after V8 protease treatment that was different from the pattern obtained when histone III was phosphorylated by stroma

  1. Regulation of Adrenal Aldosterone Production by Serine Protease Prostasin

    Directory of Open Access Journals (Sweden)

    Takehiro Ko

    2010-01-01

    Full Text Available A serine protease prostasin has been demonstrated to have a pivotal role in the activation of the epithelial sodium channel. Systemic administration of adenovirus carrying human prostasin gene in rats resulted in an increase in plasma prostasin and aldosterone levels. However, the mechanism by which the elevation of prostasin levels in the systemic circulation stimulated the plasma aldosterone levels remains unknown. Therefore, we examined if prostasin increases the aldosterone synthesis in a human adrenocortical cell line (H295R cells. Luciferase assay using CYP11B2 promoter revealed that prostasin significantly increased the transcriptional activity of CYP11B2. Prostasin significantly increased both CYP11B2 mRNA expression and aldosterone production in a dose-dependent manner. Surprisingly, treatment with camostat mesilate, a potent prostasin inhibitor, had no effect on the aldosterone synthesis by prostasin and also a protease-dead mutant of prostasin significantly stimulated the aldosterone production. A T-type/L-type calcium channel blocker and a protein kinase C (PKC inhibitor significantly reduced the aldosterone synthesis by prostasin. Our findings suggest a stimulatory effect of prostasin on the aldosterone synthesis by adrenal gland through the nonproteolytic action and indicate a new role of prostasin in the systemic circulation.

  2. A Plasmodium falciparum Strain Expressing GFP throughout the Parasite's Life-Cycle

    OpenAIRE

    Talman, Arthur M.; Blagborough, Andrew M.; Sinden, Robert E.

    2010-01-01

    The human malaria parasite Plasmodium falciparum is responsible for the majority of malaria-related deaths. Tools allowing the study of the basic biology of P. falciparum throughout the life cycle are critical to the development of new strategies to target the parasite within both human and mosquito hosts. We here present 3D7HT-GFP, a strain of P. falciparum constitutively expressing the Green Fluorescent Protein (GFP) throughout the life cycle, which has retained its capacity to complete spo...

  3. Improvement in regional CBF by L-serine contributes to its neuroprotective effect in rats after focal cerebral ischemia.

    Directory of Open Access Journals (Sweden)

    Tao-Jie Ren

    Full Text Available To investigate the mechanisms underlying the neuroprotective effect of L-serine, permanent focal cerebral ischemia was induced by occlusion of the middle cerebral artery while monitoring cerebral blood flow (CBF. Rats were divided into control and L-serine-treated groups after middle cerebral artery occlusion. The neurological deficit score and brain infarct volume were assessed. Nissl staining was used to quantify the cortical injury. L-serine and D-serine levels in the ischemic cortex were analyzed with high performance liquid chromatography. We found that L-serine treatment: 1 reduced the neurological deficit score, infarct volume and cortical neuron loss in a dose-dependent manner; 2 improved CBF in the cortex, and this effect was inhibited in the presence of apamin plus charybdotoxin while the alleviation of both neurological deficit score and infarct volume was blocked; and 3 increased the amount of L-serine and D-serine in the cortex, and inhibition of the conversion of L-serine into D-serine by aminooxyacetic acid did not affect the reduction of neurological deficit score and infarct volume by L-serine. In conclusion, improvement in regional CBF by L-serine may contribute to its neuroprotective effect on the ischemic brain, potentially through vasodilation which is mediated by the small- and intermediate-conductance Ca(2+-activated K(+ channels on the cerebral blood vessel endothelium.

  4. Capture ELISA for IgM antibodies against Plasmodium falciparum glutamate rich protein

    DEFF Research Database (Denmark)

    Dziegiel, M; Borre, Mette; Petersen, E

    1992-01-01

    This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta-galactos......This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta...

  5. High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria

    DEFF Research Database (Denmark)

    Ursing, Johan; Rombo, Lars; Bergqvist, Yngve

    2016-01-01

    BACKGROUND:  Due to development of multidrug-resistant Plasmodium falciparum new antimalarial therapies are needed. In Guinea-Bissau, routinely used triple standard-dose chloroquine remained effective for decades despite the existence of "chloroquine-resistant" P. falciparum. This study aimed...... to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. METHODS:  Standard or double-dose chloroquine was given to 892 children aged ...-up. The P. falciparum resistance-conferring genotype (pfcrt 76T) and day 7 chloroquine concentrations were determined. Data were divided into age groups (chloroquine is prescribed according to body weight. RESULTS:  Adequate clinical...

  6. A brief review on features of falciparum malaria during pregnancy

    Directory of Open Access Journals (Sweden)

    Alexandre Manirakiza

    2017-12-01

    Full Text Available Malaria in pregnancy is a serious public health problem in tropical areas. Frequently, the placenta is infected by accumulation of Plasmodium falciparum-infected erythrocytes in the intervillous space. Falciparum malaria acts during pregnancy by a range of mechanisms, and chronic or repeated infection and co-infections have insidious effects. The susceptibility of pregnant women to malaria is due to both immunological and humoral changes. Until a malaria vaccine becomes available, the deleterious effects of malaria in pregnancy can be avoided by protection against infection and prompt treatment with safe, effective antimalarial agents; however, concurrent infections such as with HIV and helminths during pregnancy are jeopardizing malaria control in sub-Saharan Africa.

  7. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...... between the anti-GLURP489-1271 and anti-(EENV)6 antibody responses. The data provide indirect evidence for a protective role of antibodies reacting with recombinant GLURP489-1271 as well as with the synthetic peptide (EENV)6 from the Pf155/RESA....

  8. RIFINs are adhesins implicated in severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Goel, Suchi; Palmkvist, Mia; Moll, Kirsten

    2015-01-01

    Rosetting is a virulent Plasmodium falciparum phenomenon associated with severe malaria. Here we demonstrate that P. falciparum–encoded repetitive interspersed families of polypeptides (RIFINs) are expressed on the surface of infected red blood cells (iRBCs), where they bind to RBCs—preferentiall......Rosetting is a virulent Plasmodium falciparum phenomenon associated with severe malaria. Here we demonstrate that P. falciparum–encoded repetitive interspersed families of polypeptides (RIFINs) are expressed on the surface of infected red blood cells (iRBCs), where they bind to RBCs......—preferentially of blood group A—to form large rosettes and mediate microvascular binding of iRBCs. We suggest that RIFINs have a fundamental role in the development of severe malaria and thereby contribute to the varying global distribution of ABO blood groups in the human population....

  9. Naturally acquired immunity to Plasmodium falciparum malaria in Africa

    DEFF Research Database (Denmark)

    Hviid, Lars

    2005-01-01

    Infection by Plasmodium falciparum parasites can lead to substantial protective immunity to malaria, and available evidence suggest that acquisition of protection against some severe malaria syndromes can be fairly rapid. Although these facts have raised hopes that the development of effective...... protective immunity to P. falciparum malaria is acquired following natural exposure to the parasites is beginning to emerge, not least thanks to studies that have combined clinical and epidemiological data with basic immunological research. This framework involves IgG with specificity for clonally variant...... antigens on the surface of the infected erythrocytes, can explain some of the difficulties in relating particular immune responses with specificity for well-defined antigenic targets to clinical protection, and suggests a radically new approach to controlling malaria-related morbidity and mortality...

  10. Molecular monitoring of Plasmodium falciparum resistance to artemisinin in Tanzania

    Directory of Open Access Journals (Sweden)

    Genton Blaise

    2006-12-01

    Full Text Available Abstract Artemisinin-based combination therapies (ACTs are recommended for use against uncomplicated malaria in areas of multi-drug resistant malaria, such as sub-Saharan Africa. However, their long-term usefulness in these high transmission areas remains unclear. It has been suggested that documentation of the S769N PfATPase6 mutations may indicate an emergence of artemisinin resistance of Plasmodium falciparum in the field. The present study assessed PfATPase6 mutations (S769N and A623E in 615 asymptomatic P. falciparum infections in Tanzania but no mutant genotype was detected. This observation suggests that resistance to artemisinin has not yet been selected in Tanzania, supporting the Ministry of Health's decision to adopt artemether+lumefantrine as first-line malaria treatment. The findings recommend further studies to assess PfATPase6 mutations in sentinel sites and verify their usefulness in monitoring emergency of ACT resistance.

  11. Historical review: Does falciparum malaria destroy isolated tribal populations?

    Science.gov (United States)

    Shanks, G Dennis

    Many isolated populations of tribal peoples were nearly destroyed when they first contacted infectious diseases particularly respiratory pathogens such as measles and smallpox. Surviving groups have often been found to have declining populations in the face of multiple social and infectious threats. Malaria, especially Plasmodium falciparum, was thought to be a major cause of depopulation in some tribal peoples isolated in tropical jungles. The dynamics of such host parasite interactions is unclear especially since most such populations would have had long histories of exposure to malaria. Three groups are individually reviewed: Meruts of Borneo, Yanomami of Amazonia, Jarawas of the Andaman Islands. The purpose of this review is to examine the role of falciparum malaria in the depopulation of some isolated tribal groups in order to understand what measures, if any, would be likely to prevent such losses. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. The Severity of Plasmodium falciparum infection is associated with transcript levels of var genes encoding endothelial protein C receptor-binding P. falciparum erythrocyte membrane protein 1

    DEFF Research Database (Denmark)

    Mkumbaye, Sixbert I; Wang, Christian W; Lyimo, Eric

    2017-01-01

    By attaching infected erythrocytes to the vascular lining, Plasmodium falciparum parasites leave blood circulation and avoid splenic clearance. This sequestration is central to pathogenesis. Severe malaria is associated with parasites expressing an antigenically distinct P. falciparum erythrocyte...

  13. Evolution of Resistance to Sulfadoxine-Pyrimethamine in Plasmodium falciparum

    OpenAIRE

    Gatton, Michelle L.; Martin, Laura B; Cheng, Qin

    2004-01-01

    The development of resistance to sulfadoxine-pyrimethamine by Plasmodium parasites is a major problem for the effective treatment of malaria, especially P. falciparum malaria. Although the molecular basis for parasite resistance is known, the factors promoting the development and transmission of these resistant parasites are less clear. This paper reports the results of a quantitative comparison of factors previously hypothesized as important for the development of drug resistance, drug dosag...

  14. In vitro adaptation of Plasmodium falciparum reveal variations in cultivability

    OpenAIRE

    White, John; Mascarenhas, Anjali; Pereira, Ligia; Dash, Rashmi; Walke, Jayashri T.; Gawas, Pooja; Sharma, Ambika; Manoharan, Suresh Kumar; Guler, Jennifer L.; Maki, Jennifer N.; Kumar, Ashwani; Mahanta, Jagadish; Valecha, Neena; Dubhashi, Nagesh; Vaz, Marina

    2016-01-01

    Background Culture-adapted Plasmodium falciparum parasites can offer deeper understanding of geographic variations in drug resistance, pathogenesis and immune evasion. To help ground population-based calculations and inferences from culture-adapted parasites, the complete range of parasites from a study area must be well represented in any collection. To this end, standardized adaptation methods and determinants of successful in vitro adaption were sought. Methods Venous blood was collected f...

  15. Cytokine profiles and antibody responses to Plasmodium falciparum ...

    African Journals Online (AJOL)

    Estimated higher ratios of IFN-γ/IL-10 and IFN-γ/IL-12 were also observed in the symptomatic children while the asymptomatic controls had higher IL-12/IL-10 ratio. The mean concentration levels of anti-P. falciparum IgG1, IgG2, IgG3 antibodies were statistically significantly higher in the individuals >5 years of age than <5 ...

  16. Reduced susceptibility of Plasmodium falciparum to artesunate in southern Myanmar.

    Directory of Open Access Journals (Sweden)

    Myat P Kyaw

    Full Text Available Plasmodium falciparum resistance to artemisinins, the first line treatment for malaria worldwide, has been reported in western Cambodia. Resistance is characterized by significantly delayed clearance of parasites following artemisinin treatment. Artemisinin resistance has not previously been reported in Myanmar, which has the highest falciparum malaria burden among Southeast Asian countries.A non-randomized, single-arm, open-label clinical trial of artesunate monotherapy (4 mg/kg daily for seven days was conducted in adults with acute blood-smear positive P. falciparum malaria in Kawthaung, southern Myanmar. Parasite density was measured every 12 hours until two consecutive negative smears were obtained. Participants were followed weekly at the study clinic for three additional weeks. Co-primary endpoints included parasite clearance time (the time required for complete clearance of initial parasitemia, parasite clearance half-life (the time required for parasitemia to decrease by 50% based on the linear portion of the parasite clearance slope, and detectable parasitemia 72 hours after commencement of artesunate treatment. Drug pharmacokinetics were measured to rule out delayed clearance due to suboptimal drug levels.The median (range parasite clearance half-life and time were 4.8 (2.1-9.7 and 60 (24-96 hours, respectively. The frequency distributions of parasite clearance half-life and time were bimodal, with very slow parasite clearance characteristic of the slowest-clearing Cambodian parasites (half-life longer than 6.2 hours in approximately 1/3 of infections. Fourteen of 52 participants (26.9% had a measurable parasitemia 72 hours after initiating artesunate treatment. Parasite clearance was not associated with drug pharmacokinetics.A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of artemisinin resistance in southern Myanmar or spread

  17. Serological evidence of discrete spatial clusters of Plasmodium falciparum parasites

    DEFF Research Database (Denmark)

    Bejon, Philip; Turner, Louise; Lavstsen, Thomas

    2011-01-01

    Malaria transmission may be considered to be homogenous with well-mixed parasite populations (as in the classic Ross/Macdonald models). Marked fine-scale heterogeneity of transmission has been observed in the field (i.e., over a few kilometres), but there are relatively few data on the degree...... of mixing. Since the Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) is highly polymorphic, the host's serological responses may be used to infer exposure to parasite sub-populations....

  18. Molecular Genetic Analysis of Parasite Survival in P. falciparum Malaria.

    Science.gov (United States)

    1991-03-15

    conducting research utilizing recombinant DNA technology , the investigator(s) adhered to current guidelines promulgated by the National Institute of Health...oligonucleotides unrelated to the conserved elements of Plasmodium falciparum were used (lane marked random oligo). Furthermore, extracts prepared...once with Ix Trager’s buffer. The following steps were carried out on ice. Erythrocytes were lysed in 0.05% saponin (19). The released parasites were

  19. Antimalarial Bioavailability and Disposition of Artesunate in Acute Falciparum Malaria

    OpenAIRE

    Newton, Paul; Suputtamongkol, Yupin; Teja-Isavadharm, Paktiya; Pukrittayakamee, Sasithon; Navaratnam, V; Bates, Imelda; White, Nicholas

    2000-01-01

    The pharmacokinetic properties of oral and intravenous artesunate (2 mg/kg of body weight) were studied in 19 adult patients with acute uncomplicated Plasmodium falciparum malaria by using a randomized crossover design. A sensitive bioassay was used to measure the antimalarial activity in plasma which results from artesunate and its principal metabolite, dihydroartemisinin. The oral study was repeated with 15 patients during convalescence. The mean absolute oral bioavailability of the antimal...

  20. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

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    Ofori Michael F

    2007-12-01

    Full Text Available Abstract Background Severe anaemia (SA, intravascular haemolysis (IVH and respiratory distress (RD are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism leading to excess anaemia in acute P. falciparum infection. Methods The direct Coombs test (DCT and flow cytometry were used to investigate the mean levels of RBC-bound complement fragments (C3d and C3bαβ and the regulatory proteins [complement receptor 1 (CD35 and decay accelerating factor (CD55] in children with discrete clinical forms of P. falciparum malaria. The relationship between the findings and clinical parameters including coma, haemoglobin (Hb levels and RD were investigated. Results Of the 484 samples tested, 131(27% were positive in DCT, out of which 115/131 (87.8% were positive for C3d alone while 16/131 (12.2% were positive for either IgG alone or both. 67.4% of the study population were below 5 years of age and DCT positivity was more common in this age group relative to children who were 5 years or older (Odds ratio, OR = 3.8; 95%CI, 2.2–6.7, p Conclusion These results suggest that complement activation contributed to anaemia in acute childhood P. falciparum malaria, possibly through induction of erythrophagocytosis and haemolysis. In contrast to other studies, this study did not find association between levels of the complement regulatory proteins, CD35 and CD55 and malarial anaemia. These findings suggest that complement activation could also be involved in the pathogenesis of RD but larger studies are needed to confirm this finding.

  1. Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras.

    Science.gov (United States)

    Lopez, Ana Cecilia; Ortiz, Andres; Coello, Jorge; Sosa-Ochoa, Wilfredo; Torres, Rosa E Mejia; Banegas, Engels I; Jovel, Irina; Fontecha, Gustavo A

    2012-11-26

    Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite's circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

  2. Heterologous Protection against Malaria after Immunization with Plasmodium falciparum Sporozoites.

    Directory of Open Access Journals (Sweden)

    Remko Schats

    Full Text Available Sterile protection in >90% of volunteers against homologous Plasmodium falciparum infection has been achieved only using the controlled human malaria infection (CHMI model. This efficient model involves whole parasite immunizations under chloroquine prophylaxis (CPS-immunization, requiring only 30-45 mosquitoes bites infected with P. falciparum-sporozoites. Given the large diversity of P. falciparum parasites, it is essential to assess protection against heterologous parasite strains.In an open-label follow-up study, 16 volunteers previously CPS-immunized and challenged with P. falciparum NF54 (West-Africa in a dose de-escalation and challenge trial were re-challenged with clone NF135.C10 (Cambodia at 14 months after the last immunization (NCT01660854.Two out of thirteen NF54 protected volunteers previously fully protected against NF54 were also fully protected against NF135.C10, while 11/13 showed a delayed patency (median prepatent period of 10.5 days (range 9.0-15.5 versus 8.5 days in 5 malaria-naïve controls (p = 0.0005. Analysis of patency by qPCR indicated a 91 to >99% estimated reduction of liver parasite load in 7/11 partially protected subjects. Three volunteers previously not protected against NF54, were also not protected against NF135.C10.This study shows that CPS-immunization can induce heterologous protection for a period of more than one year, which is a further impetus for clinical development of whole parasite vaccines.Clinicaltrials.gov NCT01660854.

  3. Serine esterase and hemolytic activity in human cloned cytotoxic T lymphocytes

    OpenAIRE

    1988-01-01

    Target cell lysis by most murine cytotoxic T lymphocytes appears to be mediated by a complement (C9)-like protein called perforin, contained in high-density cytoplasmic granules. These granules also contain high levels of serine esterase activity, which may also play a role in cytolysis. Analysis of 17 cloned human cytotoxic T lymphocytes revealed the presence of serine esterase that is very similar to its murine counterpart in substrate and inhibitor specificities, pH optimum, and molecular ...

  4. Targeting NAD+ metabolism in the human malaria parasite Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Jessica K O'Hara

    Full Text Available Nicotinamide adenine dinucleotide (NAD+ is an essential metabolite utilized as a redox cofactor and enzyme substrate in numerous cellular processes. Elevated NAD+ levels have been observed in red blood cells infected with the malaria parasite Plasmodium falciparum, but little is known regarding how the parasite generates NAD+. Here, we employed a mass spectrometry-based metabolomic approach to confirm that P. falciparum lacks the ability to synthesize NAD+ de novo and is reliant on the uptake of exogenous niacin. We characterized several enzymes in the NAD+ pathway and demonstrate cytoplasmic localization for all except the parasite nicotinamidase, which concentrates in the nucleus. One of these enzymes, the P. falciparum nicotinate mononucleotide adenylyltransferase (PfNMNAT, is essential for NAD+ metabolism and is highly diverged from the human homolog, but genetically similar to bacterial NMNATs. Our results demonstrate the enzymatic activity of PfNMNAT in vitro and demonstrate its ability to genetically complement the closely related Escherichia coli NMNAT. Due to the similarity of PfNMNAT to the bacterial enzyme, we tested a panel of previously identified bacterial NMNAT inhibitors and synthesized and screened twenty new derivatives, which demonstrate a range of potency against live parasite culture. These results highlight the importance of the parasite NAD+ metabolic pathway and provide both novel therapeutic targets and promising lead antimalarial compounds.

  5. Characterization of an eukaryotic peptide deformylase from Plasmodium falciparum.

    Science.gov (United States)

    Bracchi-Ricard, V; Nguyen, K T; Zhou, Y; Rajagopalan, P T; Chakrabarti, D; Pei, D

    2001-12-15

    Ribosomal protein synthesis in eubacteria and eukaryotic organelles initiates with an N-formylmethionyl-tRNA(i), resulting in N-terminal formylation of all nascent polypeptides. Peptide deformylase (PDF) catalyzes the subsequent removal of the N-terminal formyl group from the majority of bacterial proteins. Until recently, PDF has been thought as an enzyme unique to the bacterial kingdom. Searches of the genomic DNA databases identified several genes that encode proteins of high sequence homology to bacterial PDF from eukaryotic organisms. The cDNA encoding Plasmodium falciparum PDF (PfPDF) has been cloned and overexpressed in Escherichia coli. The recombinant protein is catalytically active in deformylating N-formylated peptides, shares many of the properties of bacterial PDF, and is inhibited by specific PDF inhibitors. Western blot analysis indicated expression of mature PfPDF in trophozoite, schizont, and segmenter stages of intraerythrocytic development. These results provide strong evidence that a functional PDF is present in P. falciparum. In addition, PDF inhibitors inhibited the growth of P. falciparum in the intraerythrocytic culture. (c)2001 Elsevier Science.

  6. Gene copy number variation throughout the Plasmodium falciparum genome

    Directory of Open Access Journals (Sweden)

    Stewart Lindsay B

    2009-08-01

    Full Text Available Abstract Background Gene copy number variation (CNV is responsible for several important phenotypes of the malaria parasite Plasmodium falciparum, including drug resistance, loss of infected erythrocyte cytoadherence and alteration of receptor usage for erythrocyte invasion. Despite the known effects of CNV, little is known about its extent throughout the genome. Results We performed a whole-genome survey of CNV genes in P. falciparum using comparative genome hybridisation of a diverse set of 16 laboratory culture-adapted isolates to a custom designed high density Affymetrix GeneChip array. Overall, 186 genes showed hybridisation signals consistent with deletion or amplification in one or more isolate. There is a strong association of CNV with gene length, genomic location, and low orthology to genes in other Plasmodium species. Sub-telomeric regions of all chromosomes are strongly associated with CNV genes independent from members of previously described multigene families. However, ~40% of CNV genes were located in more central regions of the chromosomes. Among the previously undescribed CNV genes, several that are of potential phenotypic relevance are identified. Conclusion CNV represents a major form of genetic variation within the P. falciparum genome; the distribution of gene features indicates the involvement of highly non-random mutational and selective processes. Additional studies should be directed at examining CNV in natural parasite populations to extend conclusions to clinical settings.

  7. Monkey-derived monoclonal antibodies against Plasmodium falciparum

    International Nuclear Information System (INIS)

    Stanley, H.A.; Reese, R.T.

    1985-01-01

    A system has been developed that allows efficient production of monkey monoclonal antibodies from owl monkeys. Splenocytes or peripheral blood lymphocytes from monkeys immune to the human malarial parasite, Plasmodium falciparum, were fused with P3X63 Ag8.653 mouse myelomas. The resulting hybridomas were screened by an indirect fluorescent antibody test for the production of monkey monoclonal antibodies (mAb) reactive with P. falciparum. Most of the mAb reacted with the P. falciparum merozoites and immunoprecipitated a parasite-derived glycoprotein having a relative molecular weight of 185,000. These mAb gave a minimum of five different immunoprecipitation patterns, thus demonstrating that a large number of polypeptides obtained when parasitized erythrocytes are solubilized share epitopes with this large glycoprotein. In addition, mAb were obtained that reacted with antigens associated with the infected erythrocyte membrane. One of these mAb bound a M/sub r/ 95,000 antigen. Radioimmunoprecipitation assays using 125 T-antibodies were done

  8. Human eosinophils constitutively express a unique serine protease, PRSS33.

    Science.gov (United States)

    Toyama, Sumika; Okada, Naoko; Matsuda, Akio; Morita, Hideaki; Saito, Hirohisa; Fujisawa, Takao; Nakae, Susumu; Karasuyama, Hajime; Matsumoto, Kenji

    2017-07-01

    Eosinophils play important roles in asthma, especially airway remodeling, by producing various granule proteins, chemical mediators, cytokines, chemokines and proteases. However, protease production by eosinophils is not fully understood. In the present study, we investigated the production of eosinophil-specific proteases/proteinases by transcriptome analysis. Human eosinophils and other cells were purified from peripheral blood by density gradient sedimentation and negative/positive selections using immunomagnetic beads. Protease/proteinase expression in eosinophils and release into the supernatant were evaluated by microarray analysis, qPCR, ELISA, flow cytometry and immunofluorescence staining before and after stimulation with eosinophil-activating cytokines and secretagogues. mRNAs for extracellular matrix proteins in human normal fibroblasts were measured by qPCR after exposure to recombinant protease serine 33 (PRSS33) protein (rPRSS33), created with a baculovirus system. Human eosinophils expressed relatively high levels of mRNA for metalloproteinase 25 (MMP25), a disintegrin and metalloprotease 8 (ADAM8), ADAM10, ADAM19 and PRSS33. Expression of PRSS33 was the highest and eosinophil-specific. PRSS33 mRNA expression was not affected by eosinophil-activating cytokines. Immunofluorescence staining showed that PRSS33 was co-localized with an eosinophil granule protein. PRSS33 was not detected in the culture supernatant of eosinophils even after stimulation with secretagogues, but its cell surface expression was increased. rPRSS33 stimulation of human fibroblasts increased expression of collagen and fibronectin mRNAs, at least in part via protease-activated receptor-2 activation. Activated eosinophils may induce fibroblast extracellular matrix protein synthesis via cell surface expression of PRSS33, which would at least partly explain eosinophils' role(s) in airway remodeling. Copyright © 2017 Japanese Society of Allergology. Production and hosting by Elsevier

  9. Ketamine Metabolites Enantioselectively Decrease Intracellular D-Serine Concentrations in PC-12 Cells.

    Directory of Open Access Journals (Sweden)

    Nagendra S Singh

    Full Text Available D-Serine is an endogenous NMDA receptor co-agonist that activates synaptic NMDA receptors modulating neuronal networks in the cerebral cortex and plays a key role in long-term potentiation of synaptic transmission. D-serine is associated with NMDA receptor neurotoxicity and neurodegeneration and elevated D-serine concentrations have been associated with Alzheimer's and Parkinsons' diseases and amyotrophic lateral sclerosis. Previous studies have demonstrated that the ketamine metabolites (rac-dehydronorketamine and (2S,6S-hydroxynorketamine decrease intracellular D-serine concentrations in a concentration dependent manner in PC-12 cells. In the current study, PC-12 cells were incubated with a series of ketamine metabolites and the IC50 values associated with attenuated intracellular D-serine concentrations were determined. The results demonstrate that structural and stereochemical features of the studied compounds contribute to the magnitude of the inhibitory effect with (2S,6S-hydroxynorketamine and (2R,6R-hydroxynorketamine displaying the most potent inhibition with IC50 values of 0.18 ± 0.04 nM and 0.68 ± 0.09 nM. The data was utilized to construct a preliminary 3D-QSAR/pharmacophore model for use in the design of new and more efficient modulators of D-serine.

  10. Contribution of the D-Serine-dependent pathway to the cellular mechanisms underlying cognitive aging

    Directory of Open Access Journals (Sweden)

    Emilie Rouaud

    2010-02-01

    Full Text Available An association between age-related memory impairments and changes in functional plasticity in the aging brain has been under intense study within the last decade. In this article, we show that an impaired activation of the strychnine-insensitive glycine site of N-Methyl-D-Aspartate receptors (NMDA-R by its agonist D-serine contributes to deficits of synaptic plasticity in the hippocampus of memory-impaired aged rats. Supplementation with exogenous D-serine prevents the age-related deficits of isolated NMDA-R-dependent synaptic potentials as well as those of theta-burst-induced long-term potentiation and synaptic depotentiation. Endogenous levels of D-serine are reduced in the hippocampus with aging, that correlates with a weaker expression of serine racemase synthesizing the amino acid. On the contrary, the affinity of D-serine binding to NMDA-R is not affected by aging. These results point to a critical role for the D-serine-dependent pathway in the functional alterations of the brain underlying memory impairment and provide key information in the search for new therapeutic strategies for the treatment of memory deficits in the elderly.

  11. Hexokinase 2 from Saccharomyces cerevisiae: regulation of oligomeric structure by in vivo phosphorylation at serine-14.

    Science.gov (United States)

    Behlke, J; Heidrich, K; Naumann, M; Müller, E C; Otto, A; Reuter, R; Kriegel, T

    1998-08-25

    Homodimeric hexokinase 2 from Saccharomyces cerevisiae is known to have two sites of phosphorylation: for serine-14 the modification in vivo increases with glucose exhaustion [Kriegel et al. (1994) Biochemistry 33, 148-152], while for serine-157 it occurs in vitro with ATP in the presence of nonphosphorylateable five-carbon analogues of glucose [Heidrich et al. (1997) Biochemistry 36, 1960-1964]. We show now by site-directed mutagenesis and sedimentation analysis that serine-14 phosphorylation affects the oligomeric state of hexokinase, its substitution by glutamate causing complete dissociation; glutamate exchange for serine-157 does not. Phosphorylation of wild-type hexokinase at serine-14 likewise causes dissociation in vitro. In view of the higher glucose affinity of monomeric hexokinase and the high hexokinase concentration in yeast [Womack, F., and Colowick, S. P. (1978) Arch. Biochem. Biophys. 191, 742-747; Mayes, E. L., Hoggett, J. G., and Kellett, G. L. (1983) Eur. J. Biochem. 133, 127-134], we speculate that the in vivo phosphorylation at serine-14 as transiently occurring in glucose derepression might provide a mechanism to improve glucose utilization from low level and/or that nuclear localization of the monomer might be involved in the signal transduction whereby glucose causes catabolite repression.

  12. A new world malaria map: Plasmodium falciparum endemicity in 2010.

    Science.gov (United States)

    Gething, Peter W; Patil, Anand P; Smith, David L; Guerra, Carlos A; Elyazar, Iqbal R F; Johnston, Geoffrey L; Tatem, Andrew J; Hay, Simon I

    2011-12-20

    Transmission intensity affects almost all aspects of malaria epidemiology and the impact of malaria on human populations. Maps of transmission intensity are necessary to identify populations at different levels of risk and to evaluate objectively options for disease control. To remain relevant operationally, such maps must be updated frequently. Following the first global effort to map Plasmodium falciparum malaria endemicity in 2007, this paper describes the generation of a new world map for the year 2010. This analysis is extended to provide the first global estimates of two other metrics of transmission intensity for P. falciparum that underpin contemporary questions in malaria control: the entomological inoculation rate (PfEIR) and the basic reproductive number (PfR). Annual parasite incidence data for 13,449 administrative units in 43 endemic countries were sourced to define the spatial limits of P. falciparum transmission in 2010 and 22,212 P. falciparum parasite rate (PfPR) surveys were used in a model-based geostatistical (MBG) prediction to create a continuous contemporary surface of malaria endemicity within these limits. A suite of transmission models were developed that link PfPR to PfEIR and PfR and these were fitted to field data. These models were combined with the PfPR map to create new global predictions of PfEIR and PfR. All output maps included measured uncertainty. An estimated 1.13 and 1.44 billion people worldwide were at risk of unstable and stable P. falciparum malaria, respectively. The majority of the endemic world was predicted with a median PfEIR of less than one and a median PfRc of less than two. Values of either metric exceeding 10 were almost exclusive to Africa. The uncertainty described in both PfEIR and PfR was substantial in regions of intense transmission. The year 2010 has a particular significance as an evaluation milestone for malaria global health policy. The maps presented here contribute to a rational basis for control and

  13. A new world malaria map: Plasmodium falciparum endemicity in 2010

    Directory of Open Access Journals (Sweden)

    Gething Peter W

    2011-12-01

    Full Text Available Abstract Background Transmission intensity affects almost all aspects of malaria epidemiology and the impact of malaria on human populations. Maps of transmission intensity are necessary to identify populations at different levels of risk and to evaluate objectively options for disease control. To remain relevant operationally, such maps must be updated frequently. Following the first global effort to map Plasmodium falciparum malaria endemicity in 2007, this paper describes the generation of a new world map for the year 2010. This analysis is extended to provide the first global estimates of two other metrics of transmission intensity for P. falciparum that underpin contemporary questions in malaria control: the entomological inoculation rate (PfEIR and the basic reproductive number (PfR. Methods Annual parasite incidence data for 13,449 administrative units in 43 endemic countries were sourced to define the spatial limits of P. falciparum transmission in 2010 and 22,212 P. falciparum parasite rate (PfPR surveys were used in a model-based geostatistical (MBG prediction to create a continuous contemporary surface of malaria endemicity within these limits. A suite of transmission models were developed that link PfPR to PfEIR and PfR and these were fitted to field data. These models were combined with the PfPR map to create new global predictions of PfEIR and PfR. All output maps included measured uncertainty. Results An estimated 1.13 and 1.44 billion people worldwide were at risk of unstable and stable P. falciparum malaria, respectively. The majority of the endemic world was predicted with a median PfEIR of less than one and a median PfRc of less than two. Values of either metric exceeding 10 were almost exclusive to Africa. The uncertainty described in both PfEIR and PfR was substantial in regions of intense transmission. Conclusions The year 2010 has a particular significance as an evaluation milestone for malaria global health policy. The

  14. Selection of Plasmodium falciparum Multidrug Resistance Gene 1 Alleles in Asexual Stages and Gametocytes by Artemether-Lumefantrine in Nigerian Children with Uncomplicated Falciparum Malaria ▿

    OpenAIRE

    Happi, C. T.; Gbotosho, G. O.; Folarin, O. A.; Sowunmi, A.; Hudson, T.; O'Neil, M.; Milhous, W.; Wirth, D. F.; Oduola, A. M. J.

    2008-01-01

    We assessed Plasmodium falciparum mdr1 (Pfmdr1) gene polymorphisms and copy numbers as well as P. falciparum Ca2+ ATPase (PfATPase6) gene polymorphisms in 90 Nigerian children presenting with uncomplicated falciparum malaria and enrolled in a study of the efficacy of artemether-lumefantrine (AL). The nested PCR-restriction fragment length polymorphism and the quantitative real-time PCR methodologies were used to determine the alleles of the Pfmdr1 and PfATPase6 genes and the Pfmdr1 copy numbe...

  15. Efficacy and safety of artemisinin combination therapy (ACT) for non-falciparum malaria: a systematic review

    NARCIS (Netherlands)

    Visser, Benjamin J.; Wieten, Rosanne W.; Kroon, Daniëlle; Nagel, Ingeborg M.; Bélard, Sabine; van Vugt, Michèle; Grobusch, Martin P.

    2014-01-01

    Artemisinin combination therapy (ACT) is recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria, whereas chloroquine is still commonly used for the treatment of non-falciparum species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae). A more simplified, more

  16. A plant-produced Pfs230 vaccine candidate blocks transmission of Plasmodium falciparum

    NARCIS (Netherlands)

    Farrance, C.E.; Rhee, A.; Jones, R.M.; Musiychuk, K.; Shamloul, M.; Sharma, S.; Mett, V.; Chichester, J.A.; Streatfield, S.J.; Roeffen, W.F.G.; Vegte-Bolmer, M.G. van de; Sauerwein, R.W.; Tsuboi, T.; Muratova, O.V.; Wu, Y.; Yusibov, V.

    2011-01-01

    Plasmodium falciparum is transmitted to a new host after completing its sexual cycle within a mosquito. Developing vaccines against the parasite sexual stages is a critical component in the fight against malaria. We are targeting multiple proteins of P. falciparum which are found only on the

  17. Glucose homeostasis in children with falciparum malaria: precursor supply limits gluconeogenesis and glucose production

    NARCIS (Netherlands)

    Dekker, E.; Hellerstein, M. K.; Romijn, J. A.; Neese, R. A.; Peshu, N.; Endert, E.; Marsh, K.; Sauerwein, H. P.

    1997-01-01

    To evaluate glucose kinetics in children with falciparum malaria, basal glucose production and gluconeogenesis and an estimate of the flux of the gluconeogenic precursors were measured in Kenyan children with uncomplicated falciparum malaria before (n = 11) and during infusion of alanine (1.5

  18. Drug resistance and genetic diversity of Plasmodium falciparum parasites from Suriname

    NARCIS (Netherlands)

    Peek, Ron; van Gool, Tom; Panchoe, Daynand; Greve, Sophie; Bus, Ellen; Resida, Lesley

    2005-01-01

    Plasmodium falciparum in Suriname was studied for the presence of drug resistance and genetic variation in blood samples of 86 patients with symptomatic malaria. Drug resistance was predicted by determining point mutations in the chloroquine resistance marker of the P. falciparum chloroquine

  19. Genome-wide discovery and verification of novel structured RNAs in Plasmodium falciparum

    DEFF Research Database (Denmark)

    Mourier, Tobias; Carret, Celine; Kyes, Sue

    2008-01-01

    ncRNAs in P. falciparum and are not represented in any RNA databases. We provide supporting evidence for purifying selection acting on the experimentally verified ncRNAs by comparing the nucleotide substitutions in the predicted ncRNA candidate structures in P. falciparum with the closely related...

  20. High prevalence of drug-resistance mutations in Plasmodium falciparum and Plasmodium vivax in southern Ethiopia

    Directory of Open Access Journals (Sweden)

    Löscher Thomas

    2006-07-01

    Full Text Available Abstract Background In Ethiopia, malaria is caused by both Plasmodium falciparum and Plasmodium vivax. Drug resistance of P. falciparum to sulfadoxine-pyrimethamine (SP and chloroquine (CQ is frequent and intense in some areas. Methods In 100 patients with uncomplicated malaria from Dilla, southern Ethiopia, P. falciparum dhfr and dhps mutations as well as P. vivax dhfr polymorphisms associated with resistance to SP and P. falciparum pfcrt and pfmdr1 mutations conferring CQ resistance were assessed. Results P. falciparum and P. vivax were observed in 69% and 31% of the patients, respectively. Pfdhfr triple mutations and pfdhfr/pfdhps quintuple mutations occurred in 87% and 86% of P. falciparum isolates, respectively. Pfcrt T76 was seen in all and pfmdr1 Y86 in 81% of P. falciparum. The P. vivax dhfr core mutations N117 and R58 were present in 94% and 74%, respectively. Conclusion These data point to an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia, and strongly support that both SP and CQ are inadequate drugs for this region.

  1. IgG isotypic antibodies to crude Plasmodium falciparum blood-stage ...

    African Journals Online (AJOL)

    Methods: Levels of IgG (IgG1-IgG4) and IgM to crude P. falciparum blood stage antigen ... dosage influenced P. falciparum-specific isotypic antibody responses to blood stage .... exposed Swedish donors. ..... with adverse pregnancy outcomes.

  2. Genetics of refractoriness to Plasmodium falciparum in the mosquito Anopheles stephensi

    NARCIS (Netherlands)

    Feldmann, A.M.; Gemert, Geert-Jan van; Vegte-Bolmer, Marga G. van de; Jansen, Ritsert C.

    1998-01-01

    We previously selected a line of the malaria vector mosquito Anopheles stephensi refractory (resistant) to the human malaria parasite Plasmodium falciparum, using in vitro infections with P. falciparum gametocytes. This report presents data on the genetic background of refractoriness. The results of

  3. Crystal structure and characterization of a novel L-serine ammonia-lyase from Rhizomucor miehei

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhen [College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083 (China); Yan, Qiaojuan [College of Engineering, China Agricultural University, Beijing 100083 (China); Ma, Qingjun [Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Jiang, Zhengqiang, E-mail: zhqjiang@cau.edu.cn [College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083 (China)

    2015-10-23

    L-serine ammonia-lyase, as a member of the β-family of pyridoxal-5′-phosphate (PLP) dependent enzymes, catalyzes the conversion of L-serine (L-threonine) to pyruvate (α-ketobutyrate) and ammonia. The crystal structure of L-serine ammonia-lyase from Rhizomucor miehei (RmSDH) was solved at 1.76 Å resolution by X-ray diffraction method. The overall structure of RmSDH had the characteristic β-family PLP dependent enzyme fold. It consisted of two distinct domains, both of which show the typical open twisted α/β structure. A PLP cofactor was located in the crevice between the two domains, which was attached to Lys52 by a Schiff-base linkage. Unique residue substitutions (Gly78, Pro79, Ser146, Ser147 and Thr312) were discovered at the catalytic site of RmSDH by comparison of structures of RmSDH and other reported eukaryotic L-serine ammonia-lyases. Optimal pH and temperature of the purified RmSDH were 7.5 and 40 °C, respectively. It was stable in the pH range of 7.0–9.0 and at temperatures below 40 °C. This is the first crystal structure of a fungal L-serine ammonia-lyase. It will be useful to study the catalytic mechanism of β-elimination enzymes and will provide a basis for further enzyme engineering. - Highlights: • The crystal structure of a fungal L-serine ammonia-lyase (RmSDH) was solved. • Five unique residue substitutions are found at the catalytic site of RmSDH. • RmSDH was expressed in Pichia. pastoris and biochemically characterized. • RmSDH has potential application in splitting D/L-serine.

  4. Identification and characterization of fusolisin, the Fusobacterium nucleatum autotransporter serine protease.

    Directory of Open Access Journals (Sweden)

    Lior Doron

    Full Text Available Fusobacterium nucleatum is an oral anaerobe associated with periodontal disease, adverse pregnancy outcomes and colorectal carcinoma. A serine endopeptidase of 61-65 kDa capable of damaging host tissue and of inactivating immune effectors was detected previously in F. nucleatum. Here we describe the identification of this serine protease, named fusolisin, in three oral F. nucleatum sub-species. Gel zymogram revealed fusobacterial proteolytic activity with molecular masses ranging from 55-101 kDa. All of the detected proteases were inhibited by the serine protease inhibitor PMSF. analysis revealed that all of the detected proteases are encoded by genes encoding an open reading frame (ORF with a calculated mass of approximately 115 kDa. Bioinformatics analysis of the identified ORFs demonstrated that they consist of three domains characteristic of autotransporters of the type Va secretion system. Our results suggest that the F. nucleatum fusolisins are derived from a precursor of approximately 115 kDa. After crossing the cytoplasmic membrane and cleavage of the leader sequence, the C-terminal autotransporter domain of the remaining 96-113 kDa protein is embedded in the outer membrane and delivers the N-terminal S8 serine protease passenger domain to the outer cell surface. In most strains the N-terminal catalytic 55-65 kDa domain self cleaves and liberates itself from the autotransporter domain after its transfer across the outer cell membrane. In F. nucleatum ATCC 25586 this autocatalytic activity is less efficient resulting in a full length membrane-anchored serine protease. The mature serine protease was found to cleave after Thr, Gly, Ala and Leu residues at the P1 position. Growth of F. nucleatum in complex medium was inhibited when serine protease inhibitors were used. Additional experiments are needed to determine whether fusolisin might be used as a target for controlling fusobacterial infections.

  5. The Structure of Plasmodium falciparum Blood-Stage 6-Cys Protein Pf41 Reveals an Unexpected Intra-Domain Insertion Required for Pf12 Coordination.

    Directory of Open Access Journals (Sweden)

    Michelle L Parker

    Full Text Available Plasmodium falciparum is an apicomplexan parasite and the etiological agent of severe human malaria. The complex P. falciparum life cycle is supported by a diverse repertoire of surface proteins including the family of 6-Cys s48/45 antigens. Of these, Pf41 is localized to the surface of the blood-stage merozoite through its interaction with the glycophosphatidylinositol-anchored Pf12. Our recent structural characterization of Pf12 revealed two juxtaposed 6-Cys domains (D1 and D2. Pf41, however, contains an additional segment of 120 residues predicted to form a large spacer separating its two 6-Cys domains. To gain insight into the assembly mechanism and overall architecture of the Pf12-Pf41 complex, we first determined the 2.45 Å resolution crystal structure of Pf41 using zinc single-wavelength anomalous dispersion. Structural analysis revealed an unexpected domain organization where the Pf41 6-Cys domains are, in fact, intimately associated and the additional residues instead map predominately to an inserted domain-like region (ID located between two β-strands in D1. Notably, the ID is largely proteolyzed in the final structure suggesting inherent flexibility. To assess the contribution of the ID to complex formation, we engineered a form of Pf41 where the ID was replaced by a short glycine-serine linker and showed by isothermal titration calorimetry that binding to Pf12 was abrogated. Finally, protease protection assays showed that the proteolytic susceptibility of the ID was significantly reduced in the complex, consistent with the Pf41 ID directly engaging Pf12. Collectively, these data establish the architectural organization of Pf41 and define an essential role for the Pf41 ID in promoting assembly of the Pf12-Pf41 heterodimeric complex.

  6. Erythrocytic Adenosine Monophosphate as an Alternative Purine Source in Plasmodium falciparum*

    Science.gov (United States)

    Cassera, María B.; Hazleton, Keith Z.; Riegelhaupt, Paul M.; Merino, Emilio F.; Luo, Minkui; Akabas, Myles H.; Schramm, Vern L.

    2008-01-01

    Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum. PMID:18799466

  7. Falciparum malaria infection with invasive pulmonary aspergillosis in immunocompetent host – case report

    Science.gov (United States)

    Andriyani, Y.

    2018-03-01

    Invasive pulmonary aspergillosis is an extraordinary rare in the immunocompetent host. Falciparum malaria contributes to high morbidity and mortality of malaria infection cases in the world. The impairments of both humoral and cellular immunity could be the reason of invasive pulmonary aspergillosis in falciparum malaria infection. Forty-nine years old patient came with fever, jaundice, pain in the right abdomen, after visiting a remote area in Africa about one month before admission. Blood films and rapid test were positive for Plasmodium falciparum. After malaria therapy in five days, consciousness was altered into somnolence and intubated with respiratory deterioration. Invasive pulmonary aspergillosis after falciparum malaria infection is life-threatening. There should be awareness of physicians of invasive pulmonary aspergillosis in falciparum malaria infection.

  8. Efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in Honduras.

    Science.gov (United States)

    Mejia Torres, Rosa Elena; Banegas, Engels Ilich; Mendoza, Meisy; Diaz, Cesar; Bucheli, Sandra Tamara Mancero; Fontecha, Gustavo A; Alam, Md Tauqeer; Goldman, Ira; Udhayakumar, Venkatachalam; Zambrano, Jose Orlinder Nicolas

    2013-05-01

    Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization-World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.

  9. Global sequence diversity of the lactate dehydrogenase gene in Plasmodium falciparum.

    Science.gov (United States)

    Simpalipan, Phumin; Pattaradilokrat, Sittiporn; Harnyuttanakorn, Pongchai

    2018-01-09

    Antigen-detecting rapid diagnostic tests (RDTs) have been recommended by the World Health Organization for use in remote areas to improve malaria case management. Lactate dehydrogenase (LDH) of Plasmodium falciparum is one of the main parasite antigens employed by various commercial RDTs. It has been hypothesized that the poor detection of LDH-based RDTs is attributed in part to the sequence diversity of the gene. To test this, the present study aimed to investigate the genetic diversity of the P. falciparum ldh gene in Thailand and to construct the map of LDH sequence diversity in P. falciparum populations worldwide. The ldh gene was sequenced for 50 P. falciparum isolates in Thailand and compared with hundreds of sequences from P. falciparum populations worldwide. Several indices of molecular variation were calculated, including the proportion of polymorphic sites, the average nucleotide diversity index (π), and the haplotype diversity index (H). Tests of positive selection and neutrality tests were performed to determine signatures of natural selection on the gene. Mean genetic distance within and between species of Plasmodium ldh was analysed to infer evolutionary relationships. Nucleotide sequences of P. falciparum ldh could be classified into 9 alleles, encoding 5 isoforms of LDH. L1a was the most common allelic type and was distributed in P. falciparum populations worldwide. Plasmodium falciparum ldh sequences were highly conserved, with haplotype and nucleotide diversity values of 0.203 and 0.0004, respectively. The extremely low genetic diversity was maintained by purifying selection, likely due to functional constraints. Phylogenetic analysis inferred the close genetic relationship of P. falciparum to malaria parasites of great apes, rather than to other human malaria parasites. This study revealed the global genetic variation of the ldh gene in P. falciparum, providing knowledge for improving detection of LDH-based RDTs and supporting the candidacy of

  10. Seasonal variations of vivax and falciparum malaria: an observation at a tertiary care hospital

    International Nuclear Information System (INIS)

    Jamil, S.; Khan, M.N.

    2012-01-01

    Background: Malaria is a major public health problem in the malaria endemic zones of the world. Various factors influence the prevalence of malaria. This study was conducted to determine the variation in frequency of Plasmodium vivax and Plasmodium falciparum malaria in different seasons of the year in Khyber Teaching Hospital, Peshawar. Methods: A total of 411 patients were included in the study. All these febrile patients were reported to have trophozoites of either Plasmodium vivax or Plasmodium falciparum malaria on Giemsa stained thick and thin smears. The frequency of vivax and falciparum malaria was worked out and statistically analysed for different season of the year. The study was carried out from 2nd Jan 2004 till 31st December 2008. Results: Out of total 411 diagnosed malaria cases, total 134 (32.60%) presented in the autumn season (vivax=33.58%, and falciparum=66.42%), 37 (9%) in winter season (vivax=32.4%, and falciparum=67.6%), 76 (18.49%) in spring season (vivax=93.4% and falciparum 6.6%) and 164 (39.90%) in summer season (vivax=89.6, and falciparum=10.4%). The malaria showed a highly significant pattern in different seasons of the year (p=0.00) in a way that Plasmodium falciparum malaria reached its highest frequency in autumn and winter seasons while Plasmodium vivax malaria reached its peak frequency in spring and summer seasons. Conclusion: There was highly significant seasonal variation of vivax and falciparum malaria. There is arrival of Plasmodium falciparum in autumn which peaks in winter followed by arrival of Plasmodium vivax in spring till the end of summer. (author)

  11. Cloning and sequence analysis of serine proteinase of Gloydius ussuriensis venom gland

    International Nuclear Information System (INIS)

    Sun Dejun; Liu Shanshan; Yang Chunwei; Zhao Yizhuo; Chang Shufang; Yan Weiqun

    2005-01-01

    Objective: To construct a cDNA library by using mRNA from Gloydius ussuriensis (G. Ussuriensis) venom gland, to clone and analyze serine proteinase gene from the cDNA library. Methods: Total RNA was isolated from venom gland of G. ussuriensis, mRNA was purified by using mRNA isolation Kit. The whole length cDNA was synthesized by means of smart cDNA synthesis strategy, and amplified by long distance PCR procedure, lately cDAN was cloned into vector pBluescrip-sk. The recombinant cDNA was transformed into E. coli DH5α. The cDNA of serine proteinase gene in the venom gland of G. ussuriensis was detected and amplified using the in situ hybridization. The cDNA fragment was inserted into pGEMT vector, cloned and its nucleotide sequence was determined. Results: The capacity of cDNA library of venom gland was above 2.3 x 10 6 . Its open reading frame was composed of 702 nucleotides and coded a protein pre-zymogen of 234 amino acids. It contained 12 cysteine residues. The sequence analysis indicated that the deduced amino acid sequence of the cDNA fragment shared high identity with the thrombin-like enzyme genes of other snakes in the GenBank. the query sequence exhibited strong amino acid sequence homology of 85% to the serine proteas of T. gramineus, thrombin-like serine proteinase I of D. acutus and serine protease catroxase II of C. atrox respectively. Based on the amino acid sequences of other thrombin-like enzymes, the catalytic residues and disulfide bridges of this thrombin-like enzyme were deduced as follows: catalytic residues, His 41 , Asp 86 , Ser 180 ; and six disulfide bridges Cys 7 -Cys 139 , Cys 26 -Cys 42 , Cys 74 -Cys 232 , Cys 118 -Cys 186 , Cys 150 -Cys 165 , Cys 176 -Cys 201 . Conclusion: The capacity of cDNA library of venom gland is above 2.3 x 10 6 , overtop the level of 10 5 capicity. The constructed cDNA library of G. ussuriensis venom gland would be helpful platform to detect new target genes and further gene manipulate. The cloned serine

  12. LOCALIZATION OF POLYSOME-BOUND ALBUMIN AND SERINE DEHYDRATASE IN RAT LIVER CELL FRACTIONS

    Science.gov (United States)

    Ikehara, Yukio; Pitot, Henry C.

    1973-01-01

    The polysomes involved in albumin and serine dehydratase synthesis were identified and localized by the binding to rat liver polysomes of anti-rat serum albumin and anti-serine dehydratase [125I]Fab dimer and monomer. Techniques were developed for the isolation of undegraded free and membrane-bound polysomes and for the preparation of [125I]Fab monomers and dimers from the IgG obtained from the antisera to the two proteins, rat serum albumin and serine dehydratase. The distribution of anti-rat serum albumin [125I]Fab dimer in the polysome profile is in accordance with the size of polysomes that are expected to be synthesizing albumin. By direct precipitation, it has been demonstrated that nascent chains isolated from the membrane-bound polysomes by puromycin were precipitated by anti-rat serum albumin-IgG at a level of 5–6 times those released from free polysomes. Anti-rat serum albumin-[125I]Fab dimer reacted with membrane-bound polysomes almost exclusively compared to the binding of nonimmune, control [125I]Fab dimer; a significant degree of binding of anti-rat serum albumin-[125I]Fab to free polysomes was also obtained. The [125I]Fab dimer made from normal control rabbit serum does not react with polysomes from liver at all and this preparation will not interact with polysomes extracted from tissues that do not synthesize rat serum albumin. Both anti-serine dehydratase-[125I]Fab monomer and dimer react with free and bound polysomes from livers of animals fed a chow diet or those fed a high 90% protein diet and given glucagon. In the latter instance, however, it is clear that the majority of the binding occurs to the bound polysomes. Furthermore, the specificity of this reaction may be further shown by the use of kidney polysomes that do not normally synthesize serine dehydratase. When these latter polysomes are isolated, even after the addition of crude and purified serine dehydratase, no reaction with anti-serine dehydratase-Fab fragments could be

  13. The uropathogenic species Staphylococcus saprophyticus tolerates a high concentration of D-serine.

    Science.gov (United States)

    Sakinç, Türkân; Michalski, Nadine; Kleine, Britta; Gatermann, Sören G

    2009-10-01

    Human urine contains a relatively high concentration of d-serine, which is toxic to several nonuropathogenic bacteria, but can be utilized or detoxified by uropathogenic Escherichia coli (UPEC). The sequenced genome of uropathogenic Staphylococcus saprophyticus contains a gene with homology to the d-serine deaminase gene (dsdA) of UPEC. We found the gene in several clinical isolates of S. saprophyticus; however, the gene was absent in Staphylococcus xylosus and Staphylococcus cohnii, phylogenetically close relatives of S. saprophyticus, and could also not be detected in isolates of Staphylococcus aureus, Staphylococcus epidermidis and 13 other staphylococcal species. In addition, the genomes of other sequenced staphylococci do not harbor homologues of this operon. Interestingly, S. saprophyticus could grow in media supplemented with relatively high concentrations of d-serine, whereas S. aureus, S. epidermidis and other staphylococcal species could not. The association of the dsdA gene with growth in media including d-serine was proved by introducing the gene into S. aureus Newman. Given the fact that UPEC and S. saprophyticus tolerate this compound, d-serine utilization and detoxification may be a general property of uropathogenic bacteria. © 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  14. D-Serine and Glycine Differentially Control Neurotransmission during Visual Cortex Critical Period.

    Directory of Open Access Journals (Sweden)

    Claire N J Meunier

    Full Text Available N-methyl-D-aspartate receptors (NMDARs play a central role in synaptic plasticity. Their activation requires the binding of both glutamate and d-serine or glycine as co-agonist. The prevalence of either co-agonist on NMDA-receptor function differs between brain regions and remains undetermined in the visual cortex (VC at the critical period of postnatal development. Here, we therefore investigated the regulatory role that d-serine and/or glycine may exert on NMDARs function and on synaptic plasticity in the rat VC layer 5 pyramidal neurons of young rats. Using selective enzymatic depletion of d-serine or glycine, we demonstrate that d-serine and not glycine is the endogenous co-agonist of synaptic NMDARs required for the induction and expression of Long Term Potentiation (LTP at both excitatory and inhibitory synapses. Glycine on the other hand is not involved in synaptic efficacy per se but regulates excitatory and inhibitory neurotransmission by activating strychnine-sensitive glycine receptors, then producing a shunting inhibition that controls neuronal gain and results in a depression of synaptic inputs at the somatic level after dendritic integration. In conclusion, we describe for the first time that in the VC both D-serine and glycine differentially regulate somatic depolarization through the activation of distinct synaptic and extrasynaptic receptors.

  15. Cell-type specific mechanisms of D-serine uptake and release in the brain

    Directory of Open Access Journals (Sweden)

    Magalie eMartineau

    2014-05-01

    Full Text Available Accumulating evidence during the last decade established that D-serine is a key signaling molecule utilized by neurons and astroglia in the mammalian central nervous system. D-serine is increasingly appreciated as the main physiological endogenous coagonist for synaptic NMDA receptors at central excitatory synapses; it is mandatory for long-term changes in synaptic strength, memory, learning, and social interactions. Alterations in the extracellular levels of D-serine leading to disrupted cell-cell signaling are a trademark of many chronic or acute neurological (i.e. Alzheimer disease, epilepsy, stroke and psychiatric (i.e. schizophrenia disorders, and are associated with addictive behavior (i.e. cocaine addiction. Indeed, fine tuning of the extracellular levels of D-serine, achieved by various molecular machineries and signaling pathways, is necessary for maintenance of accurate NMDA receptor functions. Here, we review the experimental data supporting the notion that astroglia and neurons use different pathways to regulate levels of extracellular D-serine.

  16. Correlation between 'H' blood group antigen and Plasmodium falciparum invasion.

    Science.gov (United States)

    Pathak, Vrushali; Colah, Roshan; Ghosh, Kanjaksha

    2016-06-01

    The ABO blood group system is the most important blood group system in clinical practice. The relationship between Plasmodium falciparum and ABO blood groups has been studied for many years. This study was undertaken to investigate the abilities of different blood group erythrocytes to support in vitro growth of P. falciparum parasites. P. falciparum parasites of four different strains (3D7, 7G8, Dd2 and RKL9) were co-cultured with erythrocytes of blood group 'A', 'B', 'O' (n = 10 for each) and 'O(h)' (Bombay group) (n = 7) for 5 days. Statistically significant differences were observed on the fourth day among the mean percent parasitemias of 'O', non-'O' ('A' and 'B') and 'O(h)' group cultures. The parasitemias of four strains ranged from 12.23 to 14.66, 11.68 to 13.24, 16.89 to 22.3, and 7.37 to 11.27 % in 'A', 'B', 'O' and Bombay group cultures, respectively. As the expression of H antigen decreased from 'O' blood group to 'A' and 'B' and then to Bombay blood group, parasite invasion (percent parasitemia) also decreased significantly (p Ulex europaeus seeds. Mean percent parasitemia of lectin-treated cultures on the fourth day was significantly lower (p < 0.05) than that of non-treated cultures and was found to be similar with the mean percent parasitemia demonstrated by the Bombay group erythrocyte cultures, thus further strengthening the hypothesis.

  17. Protein kinase A phosphorylates serine 267 in the homeodomain of engrailed-2 leading to decreased DNA binding

    DEFF Research Database (Denmark)

    Hjerrild, Majbrit; Stensballe, Allan; Jensen, Ole N

    2004-01-01

    Engrailed-2 (En-2) belongs to an evolutionarily conserved family of DNA binding homeodomain-containing proteins that are expressed in mammalian brain during development. Here, we demonstrate that serine 267 in the homeodomain of En-2 is phosphorylated by protein kinase A (PKA) in forskolin......-treated COS-7 cells. Furthermore, we analyze the physiological function of En-2 phosphorylation by PKA. The nuclear localization of En-2 is not influenced by the phosphorylation of serine 267. However, substitution of serine 267 with alanine resulted in increased binding of En-2 to DNA, while replacing serine...

  18. A multilateral effort to develop DNA vaccines against falciparum malaria.

    Science.gov (United States)

    Kumar, Sanjai; Epstein, Judith E; Richie, Thomas L; Nkrumah, Francis K; Soisson, Lorraine; Carucci, Daniel J; Hoffman, Stephen L

    2002-03-01

    Scientists from several organizations worldwide are working together to develop a multistage, multigene DNA-based vaccine against Plasmodium falciparum malaria. This collaborative vaccine development effort is named Multi-Stage DNA-based Malaria Vaccine Operation. An advisory board of international experts in vaccinology, malariology and field trials provides the scientific oversight to support the operation. This article discusses the rationale for the approach, underlying concepts and the pre-clinical development process, and provides a brief outline of the plans for the clinical testing of a multistage, multiantigen malaria vaccine based on DNA plasmid immunization technology.

  19. Computational identification of signalling pathways in Plasmodium falciparum.

    Science.gov (United States)

    Oyelade, Jelili; Ewejobi, Itunu; Brors, Benedikt; Eils, Roland; Adebiyi, Ezekiel

    2011-06-01

    Malaria is one of the world's most common and serious diseases causing death of about 3 million people each year. Its most severe occurrence is caused by the protozoan Plasmodium falciparum. Reports have shown that the resistance of the parasite to existing drugs is increasing. Therefore, there is a huge and urgent need to discover and validate new drug or vaccine targets to enable the development of new treatments for malaria. The ability to discover these drug or vaccine targets can only be enhanced from our deep understanding of the detailed biology of the parasite, for example how cells function and how proteins organize into modules such as metabolic, regulatory and signal transduction pathways. It has been noted that the knowledge of signalling transduction pathways in Plasmodium is fundamental to aid the design of new strategies against malaria. This work uses a linear-time algorithm for finding paths in a network under modified biologically motivated constraints. We predicted several important signalling transduction pathways in Plasmodium falciparum. We have predicted a viable signalling pathway characterized in terms of the genes responsible that may be the PfPKB pathway recently elucidated in Plasmodium falciparum. We obtained from the FIKK family, a signal transduction pathway that ends up on a chloroquine resistance marker protein, which indicates that interference with FIKK proteins might reverse Plasmodium falciparum from resistant to sensitive phenotype. We also proposed a hypothesis that showed the FIKK proteins in this pathway as enabling the resistance parasite to have a mechanism for releasing chloroquine (via an efflux process). Furthermore, we also predicted a signalling pathway that may have been responsible for signalling the start of the invasion process of Red Blood Cell (RBC) by the merozoites. It has been noted that the understanding of this pathway will give insight into the parasite virulence and will facilitate rational vaccine design

  20. The Plasmodium falciparum pseudoprotease SERA5 regulates the kinetics and efficiency of malaria parasite egress from host erythrocytes.

    Directory of Open Access Journals (Sweden)

    Christine R Collins

    2017-07-01

    Full Text Available Egress of the malaria parasite Plasmodium falciparum from its host red blood cell is a rapid, highly regulated event that is essential for maintenance and completion of the parasite life cycle. Egress is protease-dependent and is temporally associated with extensive proteolytic modification of parasite proteins, including a family of papain-like proteins called SERA that are expressed in the parasite parasitophorous vacuole. Previous work has shown that the most abundant SERA, SERA5, plays an important but non-enzymatic role in asexual blood stages. SERA5 is extensively proteolytically processed by a parasite serine protease called SUB1 as well as an unidentified cysteine protease just prior to egress. However, neither the function of SERA5 nor the role of its processing is known. Here we show that conditional disruption of the SERA5 gene, or of both the SERA5 and related SERA4 genes simultaneously, results in a dramatic egress and replication defect characterised by premature host cell rupture and the failure of daughter merozoites to efficiently disseminate, instead being transiently retained within residual bounding membranes. SERA5 is not required for poration (permeabilization or vesiculation of the host cell membrane at egress, but the premature rupture phenotype requires the activity of a parasite or host cell cysteine protease. Complementation of SERA5 null parasites by ectopic expression of wild-type SERA5 reversed the egress defect, whereas expression of a SERA5 mutant refractory to processing failed to rescue the phenotype. Our findings implicate SERA5 as an important regulator of the kinetics and efficiency of egress and suggest that proteolytic modification is required for SERA5 function. In addition, our study reveals that efficient egress requires tight control of the timing of membrane rupture.

  1. A retroviral oncogene, akt, encoding a serine-threonine kinase containing an SH2-like region.

    Science.gov (United States)

    Bellacosa, A; Testa, J R; Staal, S P; Tsichlis, P N

    1991-10-11

    The v-akt oncogene codes for a 105-kilodalton fusion phosphoprotein containing Gag sequences at its amino terminus. Sequence analysis of v-akt and biochemical characterization of its product revealed that it codes for a protein kinase C-related serine-threonine kinase whose cellular homolog is expressed in most tissues, with the highest amount found in thymus. Although Akt is a serine-threonine kinase, part of its regulatory region is similar to the Src homology-2 domain, a structural motif characteristic of cytoplasmic tyrosine kinases that functions in protein-protein interactions. This suggests that Akt may form a functional link between tyrosine and serine-threonine phosphorylation pathways.

  2. Identification and purification of O-acetyl-L-serine sulphhydrylase in Penicillium chrysogenum

    DEFF Research Database (Denmark)

    østergaard, Simon; Theilgaard, Hanne Birgitte; Nielsen, Jens Bredal

    1998-01-01

    We have demonstrated that Penicillium chrysogenum possesses the L-cysteine biosynthetic enzyme O-acetyI-L-serine sulphhydrylase (EC 4.2.99.8) of the direct sulphhydrylation pathway. The finding of this enzyme, and thus the presence of the direct sulphhydrylation pathway in P. chrysogenum, creates...... the potential for increasing the overall yield in penicillin production by enhancing the enzymatic activity of this microorganism. Only O-acetyl-L-serine sulphhydrylase and O-acetyl-L-homoserine sulphhydrylase (EC 4.2.99.10) have been demonstrated to use O-acetyl-L-serine as substrate for the formation of L-cysteine....... The purified enzyme did not catalyse the formation of L-homocysteine from O-acetyl-L-homoserine and sulphide, excluding the possibility that the purified enzyme was O-acetyI-L-homoserine sulphhydrylase with multiple substrate specificity. The purification enhanced the enzymatic specific activity 93-fold...

  3. Serine proteinase inhibitors from nematodes and the arms race between host and pathogen.

    Science.gov (United States)

    Zang, X; Maizels, R M

    2001-03-01

    Serine proteinase inhibitors are encoded by a large gene family of long evolutionary standing. Recent discoveries of parasite proteins that inhibit human serine proteinases, together with the complete genomic sequence from Caenorhabditis elegans, have provided a set of new serine proteinase inhibitors from more primitive metazoan animals such as nematodes. The structural features (e.g. reactive centre residues), gene organization (including intron arrangements) and inhibitory function and targets (e.g. inflammatory and coagulation pathway proteinase) all contribute important new insights into proteinase inhibitor evolution. Some parasite products have evolved that block enzymes in the mammalian host, but the human host responds with a significant immune response to the parasite inhibitors. Thus, infection produces a finely balanced conflict between host and pathogen at the molecular level, and this might have accelerated the evolution of these proteins in parasitic species as well as their hosts.

  4. l-Serine Enhances Light-Induced Circadian Phase Resetting in Mice and Humans.

    Science.gov (United States)

    Yasuo, Shinobu; Iwamoto, Ayaka; Lee, Sang-Il; Ochiai, Shotaro; Hitachi, Rina; Shibata, Satomi; Uotsu, Nobuo; Tarumizu, Chie; Matsuoka, Sayuri; Furuse, Mitsuhiro; Higuchi, Shigekazu

    2017-12-01

    Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Methods: Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before l-serine administration, and light-induced phase shifts were analyzed. In addition, the effect of l-serine on the light-induced phase advance was investigated in healthy male students (mean ± SD age 22.2 ± 1.8 y) by using dim-light melatonin onset (DLMO) determined by saliva samples as an index of the circadian phase. Results: l-Serine administration enhanced light-induced phase shifts in mice (1.86-fold; P light-dark cycle by 6 h, l-serine administration slightly accelerated re-entrainment to the shifted cycle. In humans, l-serine ingestion before bedtime induced significantly larger phase advances of DLMO after bright-light exposure during the morning (means ± SEMs-l-serine: 25.9 ± 6.6 min; placebo: 12.1 ± 7.0 min; P light-induced phase resetting in mice and humans, and it may be useful for treating circadian disturbances. © 2017 American Society for Nutrition.

  5. The serine protease inhibitor TLCK attenuates intrinsic death pathways in neurons upstream of mitochondrial demise.

    Science.gov (United States)

    Reuther, C; Ganjam, G K; Dolga, A M; Culmsee, C

    2014-11-01

    It is well-established that activation of proteases, such as caspases, calpains and cathepsins are essential components in signaling pathways of programmed cell death (PCD). Although these proteases have also been linked to mechanisms of neuronal cell death, they are dispensable in paradigms of intrinsic death pathways, e.g. induced by oxidative stress. However, emerging evidence implicated a particular role for serine proteases in mechanisms of PCD in neurons. Here, we investigated the role of trypsin-like serine proteases in a model of glutamate toxicity in HT-22 cells. In these cells glutamate induces oxytosis, a form of caspase-independent cell death that involves activation of the pro-apoptotic protein BH3 interacting-domain death agonist (Bid), leading to mitochondrial demise and ensuing cell death. In this model system, the trypsin-like serine protease inhibitor Nα-tosyl-l-lysine chloromethyl ketone hydrochloride (TLCK) inhibited mitochondrial damage and cell death. Mitochondrial morphology alterations, the impairment of the mitochondrial membrane potential and ATP depletion were prevented and, moreover, lipid peroxidation induced by glutamate was completely abolished. Strikingly, truncated Bid-induced cell death was not affected by TLCK, suggesting a detrimental activity of serine proteases upstream of Bid activation and mitochondrial demise. In summary, this study demonstrates the protective effect of serine protease inhibition by TLCK against oxytosis-induced mitochondrial damage and cell death. These findings indicate that TLCK-sensitive serine proteases play a crucial role in cell death mechanisms upstream of mitochondrial demise and thus, may serve as therapeutic targets in diseases, where oxidative stress and intrinsic pathways of PCD mediate neuronal cell death.

  6. Competitive endothelial adhesion between Plasmodium falciparum isolates under physiological flow conditions

    Directory of Open Access Journals (Sweden)

    Molyneux Malcolm

    2009-09-01

    Full Text Available Abstract Background Sequestration of parasitized red blood cells in the microvasculature of major organs involves a sequence of events that is believed to contribute to the pathogenesis of severe falciparum malaria. Plasmodium falciparum infections are commonly composed of multiple subpopulations of parasites with varied adhesive properties. A key question is: do these subpopulations compete for adhesion to endothelium? This study investigated whether, in a laboratory model of cytoadherence, there is competition in binding to endothelium between pRBC infected with P. falciparum of variant adhesive phenotypes, particularly under flow conditions. Methods Four different P. falciparum isolates, of known adherence phenotypes, were matched in pairs, mixed in different proportions and allowed to bind to cultured human endothelium. Using in vitro competitive static and flow-based adhesion assays, that allow simultaneous testing of the adhesive properties of two different parasite lines, adherence levels of paired P. falciparum isolates were quantified and analysed using either non-parametric Wilcoxon's paired signed rank test or Student paired test. Results Study findings show that P. falciparum parasite lines show marked differences in the efficiency of adhesion to endothelium. Conclusion Plasmodium falciparum variants will compete for adhesion to endothelia and variants can be ranked by their efficiency of binding. These findings suggest that variants from a mixed infection will not show uniform cytoadherence and so may vary in their ability to cause disease.

  7. Serine Protease Zymography: Low-Cost, Rapid, and Highly Sensitive RAMA Casein Zymography.

    Science.gov (United States)

    Yasumitsu, Hidetaro

    2017-01-01

    To detect serine protease activity by zymography, casein and CBB stain have been used as a substrate and a detection procedure, respectively. Casein zymography has been using substrate concentration at 1 mg/mL and employing conventional CBB stain. Although ordinary casein zymography provides reproducible results, it has several disadvantages including time-consuming and relative low sensitivity. Improved casein zymography, RAMA casein zymography, is rapid and highly sensitive. RAMA casein zymography completes the detection process within 1 h after incubation and increases the sensitivity at least by tenfold. In addition to serine protease, the method also detects metalloprotease 7 (MMP7, Matrilysin) with high sensitivity.

  8. Cloning of Plasmodium falciparum by single-cell sorting.

    Science.gov (United States)

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-10-01

    Malaria parasite cloning is traditionally carried out mainly by using the limiting dilution method, which is laborious, imprecise, and unable to distinguish multiply-infected RBCs. In this study, we used a parasite engineered to express green fluorescent protein (GFP) to evaluate a single-cell sorting method for rapidly cloning Plasmodium falciparum. By dividing a two-dimensional scattergram from a cell sorter into 17 gates, we determined the parameters for isolating singly-infected erythrocytes and sorted them into individual cultures. Pre-gating of the engineered parasites for GFP allowed the isolation of almost 100% GFP-positive clones. Compared with the limiting dilution method, the number of parasite clones obtained by single-cell sorting was much higher. Molecular analyses showed that parasite isolates obtained by single-cell sorting were highly homogenous. This highly efficient single-cell sorting method should prove very useful for cloning both P. falciparum laboratory populations from genetic manipulation experiments and clinical samples. Copyright 2010 Elsevier Inc. All rights reserved.

  9. Comparative transcriptional and genomic analysis of Plasmodium falciparum field isolates.

    Directory of Open Access Journals (Sweden)

    Margaret J Mackinnon

    2009-10-01

    Full Text Available Mechanisms for differential regulation of gene expression may underlie much of the phenotypic variation and adaptability of malaria parasites. Here we describe transcriptional variation among culture-adapted field isolates of Plasmodium falciparum, the species responsible for most malarial disease. It was found that genes coding for parasite protein export into the red cell cytosol and onto its surface, and genes coding for sexual stage proteins involved in parasite transmission are up-regulated in field isolates compared with long-term laboratory isolates. Much of this variability was associated with the loss of small or large chromosomal segments, or other forms of gene copy number variation that are prevalent in the P. falciparum genome (copy number variants, CNVs. Expression levels of genes inside these segments were correlated to that of genes outside and adjacent to the segment boundaries, and this association declined with distance from the CNV boundary. This observation could not be explained by copy number variation in these adjacent genes. This suggests a local-acting regulatory role for CNVs in transcription of neighboring genes and helps explain the chromosomal clustering that we observed here. Transcriptional co-regulation of physical clusters of adaptive genes may provide a way for the parasite to readily adapt to its highly heterogeneous and strongly selective environment.

  10. Distinct genomic architecture of Plasmodium falciparum populations from South Asia.

    Science.gov (United States)

    Kumar, Shiva; Mudeppa, Devaraja G; Sharma, Ambika; Mascarenhas, Anjali; Dash, Rashmi; Pereira, Ligia; Shaik, Riaz Basha; Maki, Jennifer N; White, John; Zuo, Wenyun; Tuljapurkar, Shripad; Duraisingh, Manoj T; Gomes, Edwin; Chery, Laura; Rathod, Pradipsinh K

    Previous whole genome comparisons of Plasmodium falciparum populations have not included collections from the Indian subcontinent, even though two million Indians contract malaria and about 50,000 die from the disease every year. Stratification of global parasites has revealed spatial relatedness of parasite genotypes on different continents. Here, genomic analysis was further improved to obtain country-level resolution by removing var genes and intergenic regions from distance calculations. P. falciparum genomes from India were found to be most closely related to each other. Their nearest neighbors were from Bangladesh and Myanmar, followed by Thailand. Samples from the rest of Southeast Asia, Africa and South America were increasingly more distant, demonstrating a high-resolution genomic-geographic continuum. Such genome stratification approaches will help monitor variations of malaria parasites within South Asia and future changes in parasite populations that may arise from in-country and cross-border migrations. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  11. Dynamic alteration in splenic function during acute falciparum malaria

    International Nuclear Information System (INIS)

    Looareesuwan, S.; Ho, M.; Wattanagoon, Y.; White, N.J.; Warrell, D.A.; Bunnag, D.; Harinasuta, T.; Wyler, D.J.

    1987-01-01

    Plasmodium-infected erythrocytes lose their normal deformability and become susceptible to splenic filtration. In animal models, this is one mechanism of antimalarial defense. To assess the effect of acute falciparum malaria on splenic filtration, we measured the clearance of heated 51 Cr-labeled autologous erythrocytes in 25 patients with acute falciparum malaria and in 10 uninfected controls. Two groups of patients could be distinguished. Sixteen patients had splenomegaly, markedly accelerated clearance of the labeled erythrocytes (clearance half-time, 8.4 +/- 4.4 minutes [mean +/- SD] vs. 62.5 +/- 36.5 minutes in controls; P less than 0.001), and a lower mean hematocrit than did the patients without splenomegaly (P less than 0.001). In the nine patients without splenomegaly, clearance was normal. After institution of antimalarial chemotherapy, however, the clearance in this group accelerated to supernormal rates similar to those in the patients with splenomegaly, but without the development of detectable splenomegaly. Clearance was not significantly altered by treatment in the group with splenomegaly. Six weeks later, normal clearance rates were reestablished in most patients in both groups. We conclude that splenic clearance of labeled erythrocytes is enhanced in patients with malaria if splenomegaly is present and is enhanced only after treatment if splenomegaly is absent. Whether this enhanced splenic function applies to parasite-infected erythrocytes in patients with malaria and has any clinical benefit will require further studies

  12. Cloning of Plasmodium falciparum by single-cell sorting

    Science.gov (United States)

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-01-01

    Malaria parasite cloning is traditionally carried out mainly by using the limiting dilution method, which is laborious, imprecise, and unable to distinguish multiply-infected RBCs. In this study, we used a parasite engineered to express green fluorescent protein (GFP) to evaluate a single-cell sorting method for rapidly cloning Plasmodium falciparum. By dividing a two dimensional scattergram from a cell sorter into 17 gates, we determined the parameters for isolating singly-infected erythrocytes and sorted them into individual cultures. Pre-gating of the engineered parasites for GFP allowed the isolation of almost 100% GFP-positive clones. Compared with the limiting dilution method, the number of parasite clones obtained by single-cell sorting was much higher. Molecular analyses showed that parasite isolates obtained by single-cell sorting were highly homogenous. This highly efficient single-cell sorting method should prove very useful for cloning both P. falciparum laboratory populations from genetic manipulation experiments and clinical samples. PMID:20435038

  13. Characterization of mitochondrion-targeted GTPases in Plasmodium falciparum.

    Science.gov (United States)

    Gupta, Kirti; Gupta, Ankit; Haider, Afreen; Habib, Saman

    2018-04-12

    Ribosome assembly is critical for translation and regulating the response to cellular events and requires a complex interplay of ribosomal RNA and proteins with assembly factors. We investigated putative participants in the biogenesis of the reduced organellar ribosomes of Plasmodium falciparum and identified homologues of two assembly GTPases - EngA and Obg that were found in mitochondria. Both are indispensable in bacteria and P. berghei EngA is among the 'essential' parasite blood stage proteins identified recently. PfEngA and PfObg1 interacted with parasite mitoribosomes in vivo. GTP stimulated PfEngA interaction with the 50S subunit of Escherichia coli surrogate ribosomes. Although PfObg1-ribosome interaction was independent of nucleotide binding, GTP hydrolysis by PfObg1 was enhanced upon ribosomal association. An additional function for PfObg1 in mitochondrial DNA transactions was suggested by its specific interaction with the parasite mitochondrial genome in vivo. Deletion analysis revealed that the positively-charged OBG (spoOB-associated GTP-binding protein) domain mediates DNA-binding. A role for PfEngA in mitochondrial genotoxic stress response was indicated by its over-expression upon methyl methanesulfonate-induced DNA damage. PfEngA had lower sensitivity to an E. coli EngA inhibitor suggesting differences with bacterial counterparts. Our results show the involvement of two important GTPases in P. falciparum mitochondrial function, with the first confirmed localization of an EngA homologue in eukaryotic mitochondria.

  14. Hepatitis C virus infection may lead to slower emergence of P. falciparum in blood.

    Directory of Open Access Journals (Sweden)

    Odile Ouwe-Missi-Oukem-Boyer

    Full Text Available BACKGROUND: Areas endemic for Plasmodium falciparum, hepatitis B virus (HBV and hepatitis C virus (HCV overlap in many parts of sub-Saharan Africa. HBV and HCV infections develop in the liver, where takes place the first development stage of P. falciparum before its further spread in blood. The complex mechanisms involved in the development of hepatitis may potentially influence the development of the liver stage of malaria parasites. Understanding the molecular mechanisms of these interactions could provide new pathophysiological insights for treatment strategies in Malaria. METHODOLOGY: We studied a cohort of 319 individuals living in a village where the three infections are prevalent. The patients were initially given a curative antimalarial treatment and were then monitored for the emergence of asexual P. falciparum forms in blood, fortnightly for one year, by microscopy and polymerase chain reaction. PRINCIPAL FINDINGS: At inclusion, 65 (20.4% subjects had detectable malaria parasites in blood, 36 (11.3% were HBV chronic carriers, and 61 (18.9% were HCV chronic carriers. During follow-up, asexual P. falciparum forms were detected in the blood of 203 patients. The median time to P. falciparum emergence in blood was respectively 140 and 120 days in HBV- and HBV+ individuals, and 135 and 224 days in HCV- and HCV+ individuals. HCV carriage was associated with delayed emergence of asexual P. falciparum forms in blood relative to patients without HCV infection. CONCLUSIONS: This pilot study represents first tentative evidence of a potential epidemiological interaction between HBV, HCV and P. falciparum infections. Age is an important confounding factor in this setting however multivariate analysis points to an interaction between P. falciparum and HCV at the hepatic level with a slower emergence of P. falciparum in HCV chronic carriers. More in depth analysis are necessary to unravel the basis of hepatic interactions between these two pathogens

  15. Drug resistance associated genetic polymorphisms in Plasmodium falciparum and Plasmodium vivax collected in Honduras, Central America.

    Science.gov (United States)

    Jovel, Irina T; Mejía, Rosa E; Banegas, Engels; Piedade, Rita; Alger, Jackeline; Fontecha, Gustavo; Ferreira, Pedro E; Veiga, Maria I; Enamorado, Irma G; Bjorkman, Anders; Ursing, Johan

    2011-12-19

    In Honduras, chloroquine and primaquine are recommended and still appear to be effective for treatment of Plasmodium falciparum and Plasmodium vivax malaria. The aim of this study was to determine the proportion of resistance associated genetic polymorphisms in P. falciparum and P. vivax collected in Honduras. Blood samples were collected from patients seeking medical attention at the Hospital Escuela in Tegucigalpa from 2004 to 2006 as well as three regional hospitals, two health centres and one regional laboratory during 2009. Single nucleotide polymorphisms in P. falciparum chloroquine resistance transporter (pfcrt), multidrug resistance 1 (pfmdr1), dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes and in P. vivax multidrug resistance 1 (pvmdr1) and dihydrofolate reductase (pvdhfr) genes were detected using PCR based methods. Thirty seven P. falciparum and 64 P. vivax samples were collected. All P. falciparum infections acquired in Honduras carried pfcrt, pfmdr1, pfdhps and pfdhfr alleles associated with chloroquine, amodiaquine and sulphadoxine-pyrimethamine sensitivity only. One patient with parasites acquired on a Pacific Island had pfcrt 76 T and pfmdr1 86Y alleles. That patient and a patient infected in West Africa had pfdhfr 51I, 59 R and 108 N alleles. Pvmdr1 976 F was found in 7/37 and two copies of pvmdr1 were found in 1/37 samples. Pvdhfr 57 L + 58 R was observed in 2/57 samples. The results indicate that P. falciparum from Honduras remain sensitive to chloroquine and sulphadoxine-pyrimethamine. This suggests that chloroquine and sulphadoxine-pyrimethamine should be efficacious for treatment of uncomplicated P. falciparum malaria, supporting current national treatment guidelines. However, genetic polymorphisms associated with chloroquine and sulphadoxine-pyrimethamine tolerance were detected in local P. vivax and imported P. falciparum infections. Continuous monitoring of the prevalence of drug resistant/tolerant P

  16. DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

    DEFF Research Database (Denmark)

    Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas Salhøj

    2014-01-01

    falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome...... of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens....

  17. Molecular modelling of calcium dependent protein kinase 4 (CDPK4) from Plasmodium falciparum

    CSIR Research Space (South Africa)

    Tsekoa, Tsepo L

    2009-10-01

    Full Text Available eukaryotic protein kinases (ePKs) as defined in model organisms. A novel family of phylogenetically distinct ePK-related genes in P. falciparum has been identified. These kinases (up to 20 in number [2], designated the FIKK family due to a conserved amino...]. The protein kinase complement of Plasmodium falciparum, the main infectious agent of lethal malaria in humans, has been analysed in detail [2, 3]. These analyses revealed that the P. falciparum kinome comprises as many as 65 sequences related to typical...

  18. Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

    Science.gov (United States)

    Laporta, Gabriel Zorello; Burattini, Marcelo Nascimento; Levy, Debora; Fukuya, Linah Akemi; de Oliveira, Tatiane Marques Porangaba; Maselli, Luciana Morganti Ferreira; Conn, Jan Evelyn; Massad, Eduardo; Bydlowski, Sergio Paulo; Sallum, Maria Anice Mureb

    2015-04-25

    Recently an unexpectedly high prevalence of Plasmodium falciparum was found in asymptomatic blood donors living in the southeastern Brazilian Atlantic forest. The bromeliad-malaria paradigm assumes that transmission of Plasmodium vivax and Plasmodium malariae involves species of the subgenus Kerteszia of Anopheles and only a few cases of P. vivax malaria are reported annually in this region. The expectations of this paradigm are a low prevalence of P. vivax and a null prevalence of P. falciparum. Therefore, the aim of this study was to verify if P. falciparum is actively circulating in the southeastern Brazilian Atlantic forest remains. In this study, anophelines were collected with Shannon and CDC-light traps in seven distinct Atlantic forest landscapes over a 4-month period. Field-collected Anopheles mosquitoes were tested by real-time PCR assay in pools of ten, and then each mosquito from every positive pool, separately for P. falciparum and P. vivax. Genomic DNA of P. falciparum or P. vivax from positive anophelines was then amplified by traditional PCR for sequencing of the 18S ribosomal DNA to confirm Plasmodium species. Binomial probabilities were calculated to identify non-random results of the P. falciparum-infected anopheline findings. The overall proportion of anophelines naturally infected with P. falciparum was 4.4% (21/480) and only 0.8% (4/480) with P. vivax. All of the infected mosquitoes were found in intermixed natural and human-modified environments and most were Anopheles cruzii (22/25 = 88%, 18 P. falciparum plus 4 P. vivax). Plasmodium falciparum was confirmed by sequencing in 76% (16/21) of positive mosquitoes, whereas P. vivax was confirmed in only 25% (1/4). Binomial probabilities suggest that P. falciparum actively circulates throughout the region and that there may be a threshold of the forested over human-modified environment ratio upon which the proportion of P. falciparum-infected anophelines increases significantly. These results

  19. Crystallization and preliminary X-ray analysis of carnein, a serine protease from Ipomoea carnea.

    NARCIS (Netherlands)

    Patel, A.K.; Oosterwijk, N. van; Singh, V.K.; Rozeboom, H.J.; Kalk, K.H.; Siezen, R.J.; Jagannadham, M.V.; Dijkstra, B.W.

    2009-01-01

    Carnein is an 80 kDa subtilisin-like serine protease from the latex of the plant Ipomoea carnea which displays an exceptional resistance to chemical and thermal denaturation. In order to obtain the first crystal structure of a plant subtilisin and to gain insight into the structural determinants

  20. Mast cells limit extracellular levels of IL-13 via a serglycin proteoglycan-serine protease axis.

    Science.gov (United States)

    Waern, Ida; Karlsson, Iulia; Thorpe, Michael; Schlenner, Susan M; Feyerabend, Thorsten B; Rodewald, Hans-Reimer; Åbrink, Magnus; Hellman, Lars; Pejler, Gunnar; Wernersson, Sara

    2012-12-01

    Mast cell (MC) granules contain large amounts of proteases of the chymase, tryptase and carboxypeptidase A (MC-CPA) type that are stored in complex with serglycin,a proteoglycan with heparin side chains. Hence, serglycinprotease complexes are released upon MC degranulation and may influence local inflammation. Here we explored the possibility that a serglycin-protease axis may regulate levels of IL-13, a cytokine involved in allergic asthma. Indeed, we found that wild-type MCs efficiently degraded exogenous or endogenously produced IL-13 upon degranulation,whereas serglycin −/− MCs completely lacked this ability.Moreover, MC-mediated IL-13 degradation was blocked both by a serine protease inhibitor and by a heparin antagonist,which suggests that IL-13 degradation is catalyzed by serglycin-dependent serine proteases and that optimal IL-13 degradation is dependent on both the serglycin and the protease component of the serglycin-protease complex.Moreover, IL-13 degradation was abrogated in MC-CPA −/−MC cultures, but was normal in cultures of MCs with an inactivating mutation of MC-CPA, which suggests that the IL-13-degrading serine proteases rely on MC-CPA protein.Together, our data implicate a serglycin-serine protease axis in the regulation of extracellular levels of IL-13. Reduction of IL-13 levels through this mechanism possibly can provide a protective function in the context of allergic inflammation.

  1. Modulation of Escherichia coli serine acetyltransferase catalytic activity in the cysteine synthase complex

    Czech Academy of Sciences Publication Activity Database

    Benoni, Roberto; De Bei, O.; Paredi, G.; Hayes, C. S.; Franko, N.; Mozzarelli, A.; Bettati, S.; Campanini, B.

    2017-01-01

    Roč. 591, č. 9 (2017), s. 1212-1224 ISSN 0014-5793 Institutional support: RVO:61388963 Keywords : cysteine synthase * protein - protein interaction * serine acetyltransferase Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 3.623, year: 2016

  2. Distinct kinetics of serine and threonine dephosphorylation are essential for mitosis

    DEFF Research Database (Denmark)

    Hein, Jamin B; Hertz, Emil P T; Garvanska, Dimitriya H

    2017-01-01

    Protein phosphatase 2A (PP2A) in complex with B55 regulatory subunits reverses cyclin-dependent kinase 1 (Cdk1) phosphorylations at mitotic exit. Interestingly, threonine and serine residues phosphorylated by Cdk1 display distinct phosphorylation dynamics, but the biological significance remains ...

  3. Engineering of the Lactococcus lactis serine proteinase by construction of hybrid enzymes

    NARCIS (Netherlands)

    Boerrigter, Ingrid J.; Buist, Girbe; Haandrikman, Alfred J.; Nijhuis, Monique; Reuver, Marjon B. de; Siezen, Roland J.; Venema, Gerhardus; Vos, Willem M. de; Kok, Jan

    Plasmids containing wild-type and hybrid proteinase genes were constructed from DNA fragments of the prtP genes of Lactococcus lactis strains Wg2 and SK11. These plasmids were introduced into the plasmid-free strain L. lactis MG1363. The serine proteinases produced by these L. lactis strains were

  4. Serine protease immunohistochemistry and lectin histochemistry in the small intestine of weaned and unweaned pigs

    DEFF Research Database (Denmark)

    Brown, P J; Poulsen, Steen Seier; Wells, M

    1991-01-01

    The distribution of goblet cells containing serine protease and of those binding the lectin Ulex europaeus agglutinin-1 (UEA-1) in the pig small intestine is altered during the period after weaning. Goblet cells exhibiting binding of other lectins were not altered. These alterations and other...

  5. Sol-gel immobilization of serine proteases for application in organic solvents

    NARCIS (Netherlands)

    van Unen, D.J.; Engbersen, Johannes F.J.; Reinhoudt, David

    2001-01-01

    The serine proteases α-chymotrypsin, trypsin, and subtilisin Carlsberg were immobilized in a sol-gel matrix and the effects on the enzyme activity in organic media are evaluated. The percentage of immobilized enzyme is 90% in the case of α-chymotrypsin and the resulting specific enzyme activity in

  6. Viral kinetics in patients with chronic hepatitis C treated with the serine protease inhibitor BILN 2061

    NARCIS (Netherlands)

    Herrmann, Eva; Zeuzem, Stefan; Sarrazin, Christoph; Hinrichsen, Holger; Benhamou, Yves; Manns, Michael P.; Reiser, Markus; Reesink, Henk; Calleja, José L.; Forns, Xavier; Steinmann, Gerhard G.; Nehmiz, Gerhard

    2006-01-01

    We analysed viral kinetics from a 2-day treatment with BILN 2061, a serine protease inhibitor of hepatitis C virus, in patients chronically infected with genotype 1 hepatitis C virus. The efficiency (E), describing inhibition of viral production, was above 99.45% in all patients with minor or

  7. Regulation of calcium release from the endoplasmic reticulum by the serine hydrolase ABHD2.

    Science.gov (United States)

    Yun, Bogeon; Lee, HeeJung; Powell, Roger; Reisdorph, Nichole; Ewing, Heather; Gelb, Michael H; Hsu, Ku-Lung; Cravatt, Benjamin F; Leslie, Christina C

    2017-09-02

    The serine hydrolase inhibitors pyrrophenone and KT195 inhibit cell death induced by A23187 and H 2 O 2 by blocking the release of calcium from the endoplasmic reticulum and mitochondrial calcium uptake. The effect of pyrrophenone and KT195 on these processes is not due to inhibition of their known targets, cytosolic phospholipase A 2 and α/β-hydrolase domain-containing (ABHD) 6, respectively, but represent off-target effects. To identify targets of KT195, fibroblasts were treated with KT195-alkyne to covalently label protein targets followed by click chemistry with biotin azide, enrichment on streptavidin beads and tryptic peptide analysis by mass spectrometry. Although several serine hydrolases were identified, α/β-hydrolase domain-containing 2 (ABHD2) was the only target in which both KT195 and pyrrophenone competed for binding to KT195-alkyne. ABHD2 is a serine hydrolase with a predicted transmembrane domain consistent with its pull-down from the membrane proteome. Subcellular fractionation showed localization of ABHD2 to the endoplasmic reticulum but not to mitochondria or mitochondrial-associated membranes. Knockdown of ABHD2 with shRNA attenuated calcium release from the endoplasmic reticulum, mitochondrial calcium uptake and cell death in fibroblasts stimulated with A23187. The results describe a novel mechanism for regulating calcium transfer from the endoplasmic reticulum to mitochondria that involves the serine hydrolase ABHD2. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Generation of serine/threonine check points in HN(C)N spectra

    Indian Academy of Sciences (India)

    Administrator

    ing to generate alanine. 6 and serine/threonine specific peak patterns. 7 have enhanced the speed of assign- ment quite substantially. These developments involved a simple modification to the pulse sequence. Continuing such efforts for rapid resonance as- signments, we have implemented here the tuning ideas.

  9. Homology modelling and protein engineering strategy of subtilases, the family of subtilisin-like serine proteinases

    NARCIS (Netherlands)

    Siezen, Roland J.; Vos, Willem M. de; Leunissen, Jack A.M.; Dijkstra, Bauke W.

    1991-01-01

    Subtilases are members of the family of subtilisin-like serine proteases. Presently, >50 subtilases are known, >40 of which with their complete amino acid sequences. We have compared these sequences and the available three-dimensional structures (subtilisin BPN', subtilisin Carlsberg, thermitase and

  10. HOMOLOGY MODELING AND PROTEIN ENGINEERING STRATEGY OF SUBTILASES, THE FAMILY OF SUBTILISIN-LIKE SERINE PROTEINASES

    NARCIS (Netherlands)

    SIEZEN, RJ; DEVOS, WM; LEUNISSEN, JAM

    1991-01-01

    Subtilases are members of the family of subtilisin-like serine proteases. Presently, > 50 subtilases are known, > 40 of which with their complete amino acid sequences. We have compared these sequences and the available three-dimensional structures (subtilisin BPN', subtilisin Carlsberg, thermitase

  11. Kazal-type serine proteinase inhibitors in the midgut of Phlebotomus papatasi

    Directory of Open Access Journals (Sweden)

    Leah Theresa Sigle

    2013-09-01

    Full Text Available Sandflies (Diptera: Psychodidae are important disease vectors of parasites of the genus Leishmania, as well as bacteria and viruses. Following studies of the midgut transcriptome of Phlebotomus papatasi, the principal vector of Leishmania major, two non-classical Kazal-type serine proteinase inhibitors were identified (PpKzl1 and PpKzl2. Analyses of expression profiles indicated that PpKzl1 and PpKzl2 transcripts are both regulated by blood-feeding in the midgut of P. papatasi and are also expressed in males, larva and pupa. We expressed a recombinant PpKzl2 in a mammalian expression system (CHO-S free style cells that was applied to in vitro studies to assess serine proteinase inhibition. Recombinant PpKzl2 inhibited α-chymotrypsin to 9.4% residual activity and also inhibited α-thrombin and trypsin to 33.5% and 63.9% residual activity, suggesting that native PpKzl2 is an active serine proteinase inhibitor and likely involved in regulating digestive enzymes in the midgut. Early stages of Leishmania are susceptible to killing by digestive proteinases in the sandfly midgut. Thus, characterising serine proteinase inhibitors may provide new targets and strategies to prevent transmission of Leishmania.

  12. Distribution of PASTA domains in penicillin-binding proteins and serine/threonine kinases of Actinobacteria.

    Science.gov (United States)

    Ogawara, Hiroshi

    2016-09-01

    PASTA domains (penicillin-binding protein and serine/threonine kinase-associated domains) have been identified in penicillin-binding proteins and serine/threonine kinases of Gram-positive Firmicutes and Actinobacteria. They are believed to bind β-lactam antibiotics, and be involved in peptidoglycan metabolism, although their biological function is not definitively clarified. Actinobacteria, especially Streptomyces species, are distinct in that they undergo complex cellular differentiation and produce various antibiotics including β-lactams. This review focuses on the distribution of PASTA domains in penicillin-binding proteins and serine/threonine kinases in Actinobacteria. In Actinobacteria, PASTA domains are detectable exclusively in class A but not in class B penicillin-binding proteins, in sharp contrast to the cases in other bacteria. In penicillin-binding proteins, PASTA domains distribute independently from taxonomy with some distribution bias. Particularly interesting thing is that no Streptomyces species have penicillin-binding protein with PASTA domains. Protein kinases in Actinobacteria possess 0 to 5 PASTA domains in their molecules. Protein kinases in Streptomyces can be classified into three groups: no PASTA domain, 1 PASTA domain and 4 PASTA domain-containing groups. The 4 PASTA domain-containing groups can be further divided into two subgroups. The serine/threonine kinases in different groups may perform different functions. The pocket region in one of these subgroup is more dense and extended, thus it may be involved in binding of ligands like β-lactams more efficiently.

  13. Oxytocin analogues with O-glycosylated serine and threonine in position 4

    Czech Academy of Sciences Publication Activity Database

    Marcinkowska, A.; Borovičková, Lenka; Slaninová, Jiřina; Grzonka, Z.

    2007-01-01

    Roč. 81, č. 7 (2007), s. 1335-1344 ISSN 0137- 5083 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z90210515 Keywords : oxytocin * glycosylated serin * glycosylated threonin * position 4 Subject RIV: CE - Biochemistry Impact factor: 0.483, year: 2007

  14. In vitro adaptation of Plasmodium falciparum reveal variations in cultivability.

    Science.gov (United States)

    White, John; Mascarenhas, Anjali; Pereira, Ligia; Dash, Rashmi; Walke, Jayashri T; Gawas, Pooja; Sharma, Ambika; Manoharan, Suresh Kumar; Guler, Jennifer L; Maki, Jennifer N; Kumar, Ashwani; Mahanta, Jagadish; Valecha, Neena; Dubhashi, Nagesh; Vaz, Marina; Gomes, Edwin; Chery, Laura; Rathod, Pradipsinh K

    2016-01-22

    Culture-adapted Plasmodium falciparum parasites can offer deeper understanding of geographic variations in drug resistance, pathogenesis and immune evasion. To help ground population-based calculations and inferences from culture-adapted parasites, the complete range of parasites from a study area must be well represented in any collection. To this end, standardized adaptation methods and determinants of successful in vitro adaption were sought. Venous blood was collected from 33 P. falciparum-infected individuals at Goa Medical College and Hospital (Bambolim, Goa, India). Culture variables such as whole blood versus washed blood, heat-inactivated plasma versus Albumax, and different starting haematocrit levels were tested on fresh blood samples from patients. In vitro adaptation was considered successful when two four-fold or greater increases in parasitaemia were observed within, at most, 33 days of attempted culture. Subsequently, parasites from the same patients, which were originally cryopreserved following blood draw, were retested for adaptability for 45 days using identical host red blood cells (RBCs) and culture media. At a new endemic area research site, ~65% of tested patient samples, with varied patient history and clinical presentation, were successfully culture-adapted immediately after blood collection. Cultures set up at 1% haematocrit and 0.5% Albumax adapted most rapidly, but no single test condition was uniformly fatal to culture adaptation. Success was not limited by low patient parasitaemia nor by patient age. Some parasites emerged even after significant delays in sample processing and even after initiation of treatment with anti-malarials. When 'day 0' cryopreserved samples were retested in parallel many months later using identical host RBCs and media, speed to adaptation appeared to be an intrinsic property of the parasites collected from individual patients. Culture adaptation of P. falciparum in a field setting is formally shown to be

  15. Exitoso cultivo in vitro de gametocitos de Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Silvia Blair

    2008-12-01

    Full Text Available Introducción. Los estadios sexuales de Plasmodium falciparum han sido menos estudiados que los estadios asexuales. Al parecer, esto se debe a la carencia de cultivos estandarizados in vitro y a la dificultad de reconocer sus estadios de desarrollo. Estos hechos no permiten el estudio de aspectos biológicos, aspectos metabólicos, expresión de genes y síntesis de proteínas durante los estadios sexuales, temas de interés en la investigación de nuevos medicamentos antipalúdicos, principalmente los aislados de plantas, y la identificación de un potencial blanco contra Plasmodium. Objetivos. Establecer un cultivo in vitro de gametocitos, con la identificación de sus cinco estadios de desarrollo, y asegurar su continua producción. Materiales y métodos. El cultivo in vitro de gametocitos se realizó a partir de la cepa NF54 de P. falciparum en medio RPMI, con determinación de la parasitemia asexual y sexual, adición de glóbulos rojos A-Rh+ sólo el primer día de cultivo y cambio diario del medio con adición de mezcla de gases (90% N2, 5% O2; 5% CO2, asegurándose que el cultivo se mantuviera a 37 °C. Cuando la parasitemia asexual estuvo entre 3% y 5%, se comenzó a agregar el doble de volumen de medio. Resultados. Se obtuvieron gametocitos en estadios I, II y III a partir del día 11 de cultivo y estadios IV y V a partir del día 14 de cultivo. Conclusiones. Se estandarizó un cultivo in vitro para estadios sexuales de P. falciparum que puede usarse para futuros estudios de evaluación de compuestos, naturales o sintéticos, que actúen sobre los gametocitos, lo cual podría permitir el desarrollo de nuevas estrategias de control contra el paludismo.

  16. Chromosome End Repair and Genome Stability in Plasmodium falciparum.

    Science.gov (United States)

    Calhoun, Susannah F; Reed, Jake; Alexander, Noah; Mason, Christopher E; Deitsch, Kirk W; Kirkman, Laura A

    2017-08-08

    The human malaria parasite Plasmodium falciparum replicates within circulating red blood cells, where it is subjected to conditions that frequently cause DNA damage. The repair of DNA double-stranded breaks (DSBs) is thought to rely almost exclusively on homologous recombination (HR), due to a lack of efficient nonhomologous end joining. However, given that the parasite is haploid during this stage of its life cycle, the mechanisms involved in maintaining genome stability are poorly understood. Of particular interest are the subtelomeric regions of the chromosomes, which contain the majority of the multicopy variant antigen-encoding genes responsible for virulence and disease severity. Here, we show that parasites utilize a competitive balance between de novo telomere addition, also called "telomere healing," and HR to stabilize chromosome ends. Products of both repair pathways were observed in response to DSBs that occurred spontaneously during routine in vitro culture or resulted from experimentally induced DSBs, demonstrating that both pathways are active in repairing DSBs within subtelomeric regions and that the pathway utilized was determined by the DNA sequences immediately surrounding the break. In combination, these two repair pathways enable parasites to efficiently maintain chromosome stability while also contributing to the generation of genetic diversity. IMPORTANCE Malaria is a major global health threat, causing approximately 430,000 deaths annually. This mosquito-transmitted disease is caused by Plasmodium parasites, with infection with the species Plasmodium falciparum being the most lethal. Mechanisms underlying DNA repair and maintenance of genome integrity in P. falciparum are not well understood and represent a gap in our understanding of how parasites survive the hostile environment of their vertebrate and insect hosts. Our work examines DNA repair in real time by using single-molecule real-time (SMRT) sequencing focused on the subtelomeric

  17. Protease-associated cellular networks in malaria parasite Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Lilburn Timothy G

    2011-12-01

    Full Text Available Abstract Background Malaria continues to be one of the most severe global infectious diseases, responsible for 1-2 million deaths yearly. The rapid evolution and spread of drug resistance in parasites has led to an urgent need for the development of novel antimalarial targets. Proteases are a group of enzymes that play essential roles in parasite growth and invasion. The possibility of designing specific inhibitors for proteases makes them promising drug targets. Previously, combining a comparative genomics approach and a machine learning approach, we identified the complement of proteases (degradome in the malaria parasite Plasmodium falciparum and its sibling species 123, providing a catalog of targets for functional characterization and rational inhibitor design. Network analysis represents another route to revealing the role of proteins in the biology of parasites and we use this approach here to expand our understanding of the systems involving the proteases of P. falciparum. Results We investigated the roles of proteases in the parasite life cycle by constructing a network using protein-protein association data from the STRING database 4, and analyzing these data, in conjunction with the data from protein-protein interaction assays using the yeast 2-hybrid (Y2H system 5, blood stage microarray experiments 678, proteomics 9101112, literature text mining, and sequence homology analysis. Seventy-seven (77 out of 124 predicted proteases were associated with at least one other protein, constituting 2,431 protein-protein interactions (PPIs. These proteases appear to play diverse roles in metabolism, cell cycle regulation, invasion and infection. Their degrees of connectivity (i.e., connections to other proteins, range from one to 143. The largest protease-associated sub-network is the ubiquitin-proteasome system which is crucial for protein recycling and stress response. Proteases are also implicated in heat shock response, signal peptide

  18. Memory B-Cell and Antibody Responses Induced by Plasmodium falciparum Sporozoite Immunization

    NARCIS (Netherlands)

    Nahrendorf, W.; Scholzen, A.; Bijker, E.M.; Teirlinck, A.C.; Bastiaens, G.J.H.; Schats, R.; Hermsen, C.C.; Visser, L.G.; Langhorne, J.; Sauerwein, R.W.

    2014-01-01

    BACKGROUND: Immunization of healthy volunteers during receipt of chemoprophylaxis with Plasmodium falciparum sporozoites (CPS-immunization) induces sterile protection from malaria. Antibody responses have long been known to contribute to naturally acquired immunity against malaria, but their

  19. Loading of erythrocyte membrane with pentacyclic triterpenes inhibits Plasmodium falciparum invasion

    DEFF Research Database (Denmark)

    Ziegler, Hanne L; Staalsø, Trine; Jaroszewski, Jerzy W

    2006-01-01

    Lupeol and betulinic acid inhibit the proliferation of Plasmodium falciparum parasites by inhibition of the invasion of merozoites into erythrocytes. This conclusion is based on experiments employing parasite cultures synchronized by magnetic cell sorting (MACS). Identical inhibitory effects were...

  20. Targeting a Novel Plasmodium falciparum Purine Recycling Pathway with Specific Immucillins

    International Nuclear Information System (INIS)

    Ting, L; Shi, W; Lewandowicz, A; Singh, V; Mwakingwe, A; Birck, M R; Taylor Ringia, E A; Bench, G; Madrid, D C; Tyler, P C; Evans, G B; Furneaux, R H; Schramm, V L; Kim, K.

    2004-01-01

    Plasmodium falciparum is unable to synthesize purine bases and relies upon purine salvage and purine recycling to meet its purine needs. We report that purines formed as products of the polyamine pathway are recycled in a novel pathway in which 5'-methylthioinosine is generated by adenosine deaminase. The action of P. falciparum purine nucleoside phosphorylase is a convergent step of purine salvage, converting both 5'-methylthioinosine and inosine to hypoxanthine. We used accelerator mass spectrometry to verify that 5'-methylthioinosine is an active nucleic acid precursor in P. falciparum. Prior studies have shown that inhibitors of purine salvage enzymes kill malaria, but potent malaria-specific inhibitors of these enzymes have not previously been described. 5'-methylthio-Immucillin-H, a transition state analogue inhibitor that is selective for malarial over human purine nucleoside phosphorylase, kills P. falciparum in culture. Immucillins are currently in clinical trials for other indications and may have application as antimalarials

  1. Defining the protein interaction network of human malaria parasite Plasmodium falciparum

    KAUST Repository

    Ramaprasad, Abhinay; Pain, Arnab; Ravasi, Timothy

    2012-01-01

    Malaria, caused by the protozoan parasite Plasmodium falciparum, affects around 225. million people yearly and a huge international effort is directed towards combating this grave threat to world health and economic development. Considerable

  2. Non-falciparum malaria infections in pregnant women in West Africa

    DEFF Research Database (Denmark)

    Williams, John; Njie, Fanta; Cairns, Matthew

    2016-01-01

    BACKGROUND: Non-Plasmodium falciparum malaria infections are found in many parts of sub-Saharan Africa but little is known about their importance in pregnancy. METHODS: Blood samples were collected at first antenatal clinic attendance from 2526 women enrolled in a trial of intermittent screening...... and treatment of malaria in pregnancy (ISTp) versus intermittent preventive treatment (IPTp) conducted in Burkina Faso, The Gambia, Ghana and Mali. DNA was extracted from blood spots and tested for P. falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium ovale using a nested PCR test. Risk factors...... for a non-falciparum malaria infection were investigated and the influence of these infections on the outcome of pregnancy was determined. RESULTS: P. falciparum infection was detected frequently (overall prevalence by PCR: 38.8 %, [95 % CI 37.0, 40.8]), with a prevalence ranging from 10.8 % in The Gambia...

  3. No seasonal accumulation of resistant P. falciparum when high-dose chloroquine is used

    DEFF Research Database (Denmark)

    Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia

    2009-01-01

    increase of pfcrt 76T if the high doses of CQ commonly used are effective. METHODS AND FINDINGS: P. falciparum parasite density, age, sex, the proportion of chloroquine resistance associated haplotypes pfcrt 76T and P. falciparum multidrug resistance gene 1 86Y were assessed in 988 samples collected from...... to become the dominant P.falciparum type in Guinea-Bissau. This is most likely due to the efficacy of high-dose chloroquine as used in Guinea-Bissau, combined with a loss of fitness associated with pfcrt 76T.......BACKGROUND: Potentially chloroquine resistant P. falciparum, identified by the 76T haplotype in the chloroquine resistance transporter (pfcrt 76T), are highly prevalent throughout Africa. In Guinea-Bissau, normal and double dose chloroquine have respective efficacies of 34% and 78% against P...

  4. Plasmodium falciparum population dynamics in a cohort of pregnant women in Senegal

    DEFF Research Database (Denmark)

    Guitard, Juliette; Andersen, Pernille; Ermont, Caroline

    2010-01-01

    Background: Pregnant women acquire protective antibodies that cross-react with geographically diverse placental Plasmodium falciparum isolates, suggesting that surface molecules expressed on infected erythrocytes by pregnancy-associated malaria (PAM) parasites have conserved epitopes and, that de...

  5. Multiplicity of Plasmodium falciparum infection following intermittent preventive treatment in infants

    NARCIS (Netherlands)

    Buchholz, Ulrike; Kobbe, Robin; Danquah, Ina; Zanger, Philipp; Reither, Klaus; Abruquah, Harry H.; Grobusch, Martin P.; Ziniel, Peter; May, Jürgen; Mockenhaupt, Frank P.

    2010-01-01

    Intermittent preventive treatment in infants with sulphadoxine-pyrimethamine (IPTi-SP) reduces malaria morbidity by 20% to 33%. Potentially, however, this intervention may compromise the acquisition of immunity, including the tolerance towards multiple infections with Plasmodium falciparum.

  6. Ozone-induced airway hyperresponsiveness in patients with asthma: role of neutrophil-derived serine proteinases.

    Science.gov (United States)

    Hiltermann, T J; Peters, E A; Alberts, B; Kwikkers, K; Borggreven, P A; Hiemstra, P S; Dijkman, J H; van Bree, L A; Stolk, J

    1998-04-01

    Proteinase inhibitors may be of potential therapeutic value in the treatment of respiratory diseases such as chronic obstructive pulmonary disease (COPD) or asthma. Our aim was to study the role of neutrophils, and neutrophil-derived serine proteinases in an acute model in patients with asthma. Exposure to ozone induces an acute neutrophilic inflammatory reaction accompanied by an increase in airway hyperresponsiveness. It is thought that these two effects of ozone are linked, and that neutrophil-derived serine proteinases (i.e. elastase) may play a role in the ozone-induced airway hyperresponsiveness. Therefore, we examined the effect of recombinant antileukoprotease (rALP), one of the major serine proteinase inhibitors in the lung, on ozone-induced changes in airway hyperresponsiveness in this model. We observed that 16 h after exposure to ozone, airway hyperresponsiveness to methacholine was increased both following placebo and rALP treatment. There was no significant difference between placebo and rALP treatment (change in area under the dose-response curve to methacholine: 117.3+/-59.0 vs 193.6+/-59.6 % fall x DD; p=.12). Moreover, the immediate decrease in FEV1 after ozone exposure was not significantly different between the two groups (placebo: -29.6+/-6.7%; rALP: -20.9+/-3.8%; p=.11). In addition, no significant differences were observed in plasma levels of fibrinogen degradation products generated by neutrophil serine proteinases before and after exposure to ozone. We conclude that neutrophil-derived serine proteinases are not important mediators for ozone-induced hyperresponsiveness.

  7. Construction of a system for heterologous production of carbonic anhydrase from Plasmodium falciparum in Pichia pastoris

    OpenAIRE

    Gullberg, Erik

    2008-01-01

    Malaria is one of the biggest current global health problems, and with the increasing occurance of drug resistant Plasmodium falciparum strains, there is an urgent need for new antimalarial drugs. Given the important role of carbonic anhydrase in Plasmodium falciparum (PfCA), it is a potential novel drug target. Heterologous expression of malaria proteins is problematic due to the unusual codon usage of the Plasmodium genome, so to overcome this problem a synthetic PfCA gene was designed, opt...

  8. Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

    Science.gov (United States)

    2010-06-17

    Sciences, Bethesda, MD, ...... 14. ABSTRACT Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is...parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of...Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum Carmenza Spadafora1,2,3, Gordon A. Awandare4

  9. Plasmodium Falciparum: Adhesion Phenotype of Infected Erythrocytes Using Classical and Mini-Column Cytoadherence Techniques

    Directory of Open Access Journals (Sweden)

    N Kalantari

    2013-03-01

    Full Text Available Background: Cytoadherence of Plasmodium falciparum- infected erythrocytes to host cells is an impor­tant trait for parasite survival and has a major role in pathology of malaria disease. Infections with P. falciparum usually consist of several subpopulations of parasites with different adhesive proper­ties. This study aimed to compare relative sizes of various binding subpopulations of different P. falciparum isolates. It also investigated the adhesive phenotype of a laboratory P. falciparum line, A4, using different binding techniques.Methods: Seven different P. falciparum isolates (ITG, A4, 3D7 and four field isolates were cultivated to late trophozoite and schizont and then cytoadherence to cell differentiation 36 (CD36, intercellu­lar cell adhesion molecule-1 (ICAM-1, and vascular cell adhesion molecule (V-CAM and E-selectin were examined. The relative binding sizes of parasite subpopulations to human receptors were meas­ured by mini-column cytoadherence method. The adhesion phenotype of P. falciparum-A4 line was evaluated by in vitro static, flow-based and mini-column binding assays.Results: The relative binding size of ITG, A4 and 3D7 clones to a column made with CHO/ICAM-1 was 68%, 54% and 0%, respectively. The relative binding sizes of these lines to CHO/CD36 were 59.7%, 28.7% and 0%, respectively. Different field isolates had variable sizes of respective CD36 and ICAM1-binding subpopulations. A4 line had five different subpopulations each with different binding sizes.Conclusion: This study provided further evidence that P. falciparum isolates have different binding subpopulations sizes in an infection. Furthermore, measurement of ICAM-1 or CD36 binding subpopula­tions may practical to study the cytoadherence phenotypes of P. falciparum field isolates at the molecular level.

  10. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes

    DEFF Research Database (Denmark)

    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia

    2014-01-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated...... with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized...

  11. A simple field kit for the determination of drug susceptibility in Plasmodium falciparum.

    Science.gov (United States)

    Nguyen-Dinh, P; Magloire, R; Chin, W

    1983-05-01

    A field kit has been developed which greatly simplifies the performance of the 48-hour in vitro test for drug resistance in Plasmodium falciparum. The kit uses an easily reconstituted lyophilized culture medium, and requires only a fingerprick blood sample. In parallel tests with 13 isolates of P. falciparum in Haiti, the new technique had a success rate equal to that of the previously described method, with comparable results in terms of parasite susceptibility in vitro to chloroquine and pyrimethamine.

  12. Anti-phospholipid antibodies in patients with Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Jakobsen, P H; Morris-Jones, S D; Hviid, L

    1993-01-01

    Plasma levels of antibodies against phosphatidylinositol (PI), phosphatidylcholine (PC) and cardiolipin (CL) were measured by enzyme-linked immunosorbent assay (ELISA) in patients from malaria endemic area of Sudan and The Gambia. Some Sudanese adults produced IgM antibodies against all three types...... of phospholipids (PL) during an acute Plasmodium falciparum infection. The anti-PL antibody titre returned to preinfection levels in most of the donors 30 days after the disease episode. IgG titres against PI, PC and CL were low. In Gambian children with malaria, IgM antibody titres against PI and PC were...... significantly higher in those with severe malaria than in those with mild malaria. These results show that a proportion of malaria patients produce anti-PL antibodies during infection and that titres of these antibodies are associated with the severity of disease....

  13. Multiple populations of artemisinin-resistant Plasmodium falciparum in Cambodia

    Science.gov (United States)

    Miotto, Olivo; Almagro-Garcia, Jacob; Manske, Magnus; MacInnis, Bronwyn; Campino, Susana; Rockett, Kirk A; Amaratunga, Chanaki; Lim, Pharath; Suon, Seila; Sreng, Sokunthea; Anderson, Jennifer M; Duong, Socheat; Nguon, Chea; Chuor, Char Meng; Saunders, David; Se, Youry; Lon, Chantap; Fukuda, Mark M; Amenga-Etego, Lucas; Hodgson, Abraham VO; Asoala, Victor; Imwong, Mallika; Takala-Harrison, Shannon; Nosten, Francois; Su, Xin-zhuan; Ringwald, Pascal; Ariey, Frédéric; Dolecek, Christiane; Hien, Tran Tinh; Boni, Maciej F; Thai, Cao Quang; Amambua-Ngwa, Alfred; Conway, David J; Djimdé, Abdoulaye A; Doumbo, Ogobara K; Zongo, Issaka; Ouedraogo, Jean-Bosco; Alcock, Daniel; Drury, Eleanor; Auburn, Sarah; Koch, Oliver; Sanders, Mandy; Hubbart, Christina; Maslen, Gareth; Ruano-Rubio, Valentin; Jyothi, Dushyanth; Miles, Alistair; O’Brien, John; Gamble, Chris; Oyola, Samuel O; Rayner, Julian C; Newbold, Chris I; Berriman, Matthew; Spencer, Chris CA; McVean, Gilean; Day, Nicholas P; White, Nicholas J; Bethell, Delia; Dondorp, Arjen M; Plowe, Christopher V; Fairhurst, Rick M; Kwiatkowski, Dominic P

    2013-01-01

    We describe an analysis of genome variation in 825 Plasmodium falciparum samples from Asia and Africa that reveals an unusual pattern of parasite population structure at the epicentre of artemisinin resistance in western Cambodia. Within this relatively small geographical area we have discovered several distinct but apparently sympatric parasite subpopulations with extremely high levels of genetic differentiation. Of particular interest are three subpopulations, all associated with clinical resistance to artemisinin, which have skewed allele frequency spectra and remarkably high levels of haplotype homozygosity, indicative of founder effects and recent population expansion. We provide a catalogue of SNPs that show high levels of differentiation in the artemisinin-resistant subpopulations, including codon variants in various transporter proteins and DNA mismatch repair proteins. These data provide a population genetic framework for investigating the biological origins of artemisinin resistance and for defining molecular markers to assist its elimination. PMID:23624527

  14. Spatial prediction of Plasmodium falciparum prevalence in Somalia.

    Science.gov (United States)

    Noor, Abdisalan M; Clements, Archie C A; Gething, Peter W; Moloney, Grainne; Borle, Mohammed; Shewchuk, Tanya; Hay, Simon I; Snow, Robert W

    2008-08-21

    Maps of malaria distribution are vital for optimal allocation of resources for anti-malarial activities. There is a lack of reliable contemporary malaria maps in endemic countries in sub-Saharan Africa. This problem is particularly acute in low malaria transmission countries such as those located in the horn of Africa. Data from a national malaria cluster sample survey in 2005 and routine cluster surveys in 2007 were assembled for Somalia. Rapid diagnostic tests were used to examine the presence of Plasmodium falciparum parasites in finger-prick blood samples obtained from individuals across all age-groups. Bayesian geostatistical models, with environmental and survey covariates, were used to predict continuous maps of malaria prevalence across Somalia and to define the uncertainty associated with the predictions. For analyses the country was divided into north and south. In the north, the month of survey, distance to water, precipitation and temperature had no significant association with P. falciparum prevalence when spatial correlation was taken into account. In contrast, all the covariates, except distance to water, were significantly associated with parasite prevalence in the south. The inclusion of covariates improved model fit for the south but not for the north. Model precision was highest in the south. The majority of the country had a predicted prevalence of or = 5% prevalence were predominantly in the south. The maps showed that malaria transmission in Somalia varied from hypo- to meso-endemic. However, even after including the selected covariates in the model, there still remained a considerable amount of unexplained spatial variation in parasite prevalence, indicating effects of other factors not captured in the study. Nonetheless the maps presented here provide the best contemporary information on malaria prevalence in Somalia.

  15. Prevalence of Plasmodium falciparum infection in pregnant women in Gabon

    Directory of Open Access Journals (Sweden)

    Kendjo Eric

    2003-06-01

    Full Text Available Abstract Background In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon. Methods Peripheral blood was collected from 311 primigravidae and women in their second pregnancy. Thick blood smears were checked, as were the results of haemoglobin electrophoresis. We also looked for the presence of anaemia, fever, and checked whether the volunteers had had chemoprophylaxis. The study was performed in Gabon where malaria transmission is intense and perennial. Results A total of 177 women (57% had microscopic parasitaemia; 139 (64%of them were primigravidae, 38 (40% in their second pregnancy and 180 (64% were teenagers. The parasites densities were also higher in primigravidae and teenagers. The prevalence of anaemia was 71% and was associated with microscopic Plasmodium falciparum parasitaemia: women with moderate or severe anaemia had higher parasite prevalences and densities. However, the sickle cell trait, fever and the use of chemoprophylaxis did not have a significant association with the presence of P. falciparum. Conclusions These results suggest that the prevalence of malaria and the prevalence of anaemia, whether associated with malaria or not, are higher in pregnant women in Gabon. Primigravidae and young pregnant women are the most susceptible to infection. It is, therefore, urgent to design an effective regimen of malaria prophylaxis for this high risk population.

  16. Spatial prediction of Plasmodium falciparum prevalence in Somalia

    Directory of Open Access Journals (Sweden)

    Shewchuk Tanya

    2008-08-01

    Full Text Available Abstract Background Maps of malaria distribution are vital for optimal allocation of resources for anti-malarial activities. There is a lack of reliable contemporary malaria maps in endemic countries in sub-Saharan Africa. This problem is particularly acute in low malaria transmission countries such as those located in the horn of Africa. Methods Data from a national malaria cluster sample survey in 2005 and routine cluster surveys in 2007 were assembled for Somalia. Rapid diagnostic tests were used to examine the presence of Plasmodium falciparum parasites in finger-prick blood samples obtained from individuals across all age-groups. Bayesian geostatistical models, with environmental and survey covariates, were used to predict continuous maps of malaria prevalence across Somalia and to define the uncertainty associated with the predictions. Results For analyses the country was divided into north and south. In the north, the month of survey, distance to water, precipitation and temperature had no significant association with P. falciparum prevalence when spatial correlation was taken into account. In contrast, all the covariates, except distance to water, were significantly associated with parasite prevalence in the south. The inclusion of covariates improved model fit for the south but not for the north. Model precision was highest in the south. The majority of the country had a predicted prevalence of Conclusion The maps showed that malaria transmission in Somalia varied from hypo- to meso-endemic. However, even after including the selected covariates in the model, there still remained a considerable amount of unexplained spatial variation in parasite prevalence, indicating effects of other factors not captured in the study. Nonetheless the maps presented here provide the best contemporary information on malaria prevalence in Somalia.

  17. Confirmation of emergence of mutations associated with atovaquone-proguanil resistance in unexposed Plasmodium falciparum isolates from Africa

    OpenAIRE

    Happi, Christian T; Gbotosho, Grace O; Folarin, Onikepe A; Milner, Danny; Sarr, Ousmane; Sowunmi, Akintunde; Kyle, Dennis E; Milhous, Wilbur K; Wirth, Dyann F; Oduola, Ayoade MJ

    2006-01-01

    Abstract Background In vitro and in vivo resistance of Plasmodium falciparum to atovaquone or atovaquone-proguanil hydrochloride combination has been associated to two point mutations in the parasite cytochrome b (cytb) gene (Tyr268Ser and Tyr268Asn). However, little is known about the prevalence of codon-268 mutations in natural populations of P. falciparum without previous exposure to the drug in Africa. Methods The prevalence of codon-268 mutations in the cytb gene of African P. falciparum...

  18. Malaria falciparum y síndrome nefrótico: nuestras experiencias Falciparum malaria and nephrotic Síndrome: Our experience

    Directory of Open Access Journals (Sweden)

    Jesús Juan Rodríguez

    2007-03-01

    Full Text Available Las especies de Plasmodium que infectan al hombre son: P. vivax, P. Malariae, P. Ovale y P. Falciparum. En Mozambique, como en la mayor parte de la llamada África Subsahariana, la especie predominante es P. falciparum cloroquina resistente. La infección por P. falciparum es potencialmente mortal, tiende a manifestarse como una enfermedad febril sin signos localizados o específicos. En los casos más graves, sin embargo puede presentarse asociada a variados síndromes clínicos que plantean serios retos terapéuticos.Es reconocido que la malaria o paludismo puede asociarse a síndrome nefrótico y se han dado explicaciones de esta relación patogénica. En Mozambique, en un período de seis meses, tuvimos la oportunidad de tratar tres casos de Malaria falciparum grave, asociado a síndrome nefrótico.Divulgar y trasmitir las experiencias prácticas y consideraciones teóricas a propósito de uno de estos casos es la motivación de los autores de este trabajo.Plasmodiumspecies infecting man are the following: P.vivax, P. Malariae, P. Ovale and P. Falciparum. In Mozambique, like the biggest area from the so called Subsaharian Africa,the resistent-chloroquine P. Falciparum is the predominating specie in this area. The P. Falciparum infection is potentially fatal, with a trend to show as a febrile condition with no localized or specific signs. In more severe cases, however, it may be presented in association with different clinical syndromes which represent serious therapeutic challenges. It is not unknown that Malaria or Paludism may be associated with the Nephrotic Syndrome, and many explanations have been given on this pathogenic relatioship. In a sixth month's period in Mozambique we had the chance to test three severe cases of Falciparum Malaria associated with a Nephrotic Syndrome. Spreading the practical experience and theoretic considerations on one of these cases is the aim of this work.

  19. Increased prevalence of Plasmodium falciparum malaria in Honduras, Central America Aumento de la prevalencia de malaria por Plasmodium falciparum en Honduras, Centroamerica

    Directory of Open Access Journals (Sweden)

    Carol J. Palmer

    1998-07-01

    Full Text Available We report on our investigation of a malaria outbreak in Honduras, Central America, in January 1997. We tested 202 patients with fever and chills using thin and thick blood film microscopy. Sixteen patients lived in the city and the rest lived in rural areas. A total of 95 samples (47% were positive for malaria parasites. Seventy-nine percent (63/80 of the rural patients were infected with Plasmodium vivax and 21% (17/80 were infected with P. falciparum. In the urban area, all 15 infected patients had P. vivax malaria and none showed evidence of P. falciparum. Since previous reports indicate that falciparum malaria accounts for only 2% of the overall malaria infections in Honduras, the results reported here suggest that there is a dramatic increase in falciparum malaria in the area of Honduras investigated in this study.Notificamos los resultados de un estudio de un brote de malaria que se produjo en Honduras, Centroamérica, en enero de 1997. Sometimos a examen microscópico frotis delgados y frotis gruesos de la sangre de 202 pacientes con fiebre y escalofríos. Dieciséis pacientes eran habitantes de la zona urbana y el resto de la zona rural. Un total de 95 especímenes (47% fueron positivos a parásitos de la malaria. Setenta y ocho por ciento (62/80 de los pacientes del área rural estaban infestados con Plasmodium vivax y 22% (17/80 con P. falciparum. En la zona urbana, todos los 15 pacientes que estaban infestados tenían P. vivax y en ninguno se detectó P. falciparum. Ya que según informes previos la malaria de tipo falciparum representa solamente 2% de todos los casos de malaria en Honduras, nuestros resultados sugieren que hay un gran incremento del número de casos de malaria falciparum en la zona de Honduras en que se llevó a cabo esta investigación.

  20. The Glycerate and Phosphorylated Pathways of Serine Synthesis in Plants: The Branches of Plant Glycolysis Linking Carbon and Nitrogen Metabolism.

    Science.gov (United States)

    Igamberdiev, Abir U; Kleczkowski, Leszek A

    2018-01-01

    Serine metabolism in plants has been studied mostly in relation to photorespiration where serine is formed from two molecules of glycine. However, two other pathways of serine formation operate in plants and represent the branches of glycolysis diverging at the level of 3-phosphoglyceric acid. One branch (the glycerate - serine pathway) is initiated in the cytosol and involves glycerate formation from 3-phosphoglycerate, while the other (the phosphorylated serine pathway) operates in plastids and forms phosphohydroxypyruvate as an intermediate. Serine formed in these pathways becomes a precursor of glycine, formate and glycolate accumulating in stress conditions. The pathways can be linked to GABA shunt via transamination reactions and via participation of the same reductase for both glyoxylate and succinic semialdehyde. In this review paper we present a hypothesis of the regulation of redox balance in stressed plant cells via participation of the reactions associated with glycerate and phosphorylated serine pathways. We consider these pathways as important processes linking carbon and nitrogen metabolism and maintaining cellular redox and energy levels in stress conditions.

  1. AQP4 plasma membrane trafficking or channel gating is not significantly modulated by phosphorylation at C-terminal serine residues

    DEFF Research Database (Denmark)

    Assentoft, Mette; Larsen, Brian R; Olesen, Emma T B

    2014-01-01

    heterologous expression in Xenopus laevis oocytes (along with serine-to-aspartate mutants of the same residues to mimic a phosphorylation). None of the mutant AQP4 constructs displayed alterations in the unit water permeability. Thus phosphorylation of six different serine residues in the COOH terminus of AQP4....... Phosphorylation of aquaporins can regulate plasma membrane localization and, possibly, the unit water permeability via gating of the AQP channel itself. In vivo phosphorylation of six serine residues in the COOH terminus of AQP4 has been detected by mass spectrometry: Ser(276), Ser(285), Ser(315), Ser(316), Ser...

  2. Incorporation of glycine and serine into sporulating cells of Bacillus subtilis

    International Nuclear Information System (INIS)

    Mitani, Takahiko; Kadota, Hajime

    1976-01-01

    The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat. (auth.)

  3. The Occurrence of Type S1A Serine Proteases in Sponge and Jellyfish

    Science.gov (United States)

    Rojas, Ana; Doolittle, Russell F.

    2003-01-01

    Although serine proteases are found in all kinds of cellular organisms and many viruses, the classic "chymotrypsin family" (Group S1A by th e 1998 Barrett nomenclature) has an unusual phylogenetic distribution , being especially common in animals, entirely absent from plants and protists, and rare among fungi. The distribution in Bacteria is larg ely restricted to the genus Streptomyces, although a few isolated occ urrences in other bacteria have been reported. The family may be enti rely absent from Archaea. Although more than a thousand sequences have been reported for enzymes of this type from animals, none of them ha ve been from early diverging phyla like Porifera or Cnidaria, We now report the existence of Group SlA serine proteases in a sponge (phylu m Porifera) and a jellyfish (phylum Cnidaria), making it safe to conc lude that all animal groups possess these enzymes.

  4. Characterization of the Usage of the Serine Metabolic Network in Human Cancer

    Directory of Open Access Journals (Sweden)

    Mahya Mehrmohamadi

    2014-11-01

    Full Text Available The serine, glycine, one-carbon (SGOC metabolic network is implicated in cancer pathogenesis, but its general functions are unknown. We carried out a computational reconstruction of the SGOC network and then characterized its expression across thousands of cancer tissues. Pathways including methylation and redox metabolism exhibited heterogeneous expression indicating a strong context dependency of their usage in tumors. From an analysis of coexpression, simultaneous up- or downregulation of nucleotide synthesis, NADPH, and glutathione synthesis was found to be a common occurrence in all cancers. Finally, we developed a method to trace the metabolic fate of serine using stable isotopes, high-resolution mass spectrometry, and a mathematical model. Although the expression of single genes didn’t appear indicative of flux, the collective expression of several genes in a given pathway allowed for successful flux prediction. Altogether, these findings identify expansive and heterogeneous functions for the SGOC metabolic network in human cancer.

  5. Thrombocytin, a serine protease from Bothrops atrox venom. 1. Purification and characterization of the enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, E.P. (Temple Univ. Health Sciences Center, Philadelphia, PA); Niewiarowski, S.; Stocker, K.; Kettner, C.; Shaw, E.; Brudzynsi, T.M.

    1979-08-07

    Thrombocytin, a platelet-activating enzyme from Bothrops atrox venom, has been purified to homogeneity by precipitation with sodium salicylate and chromatography on heparin-agarose. Thrombocytin is a single-chain glycoprotein with a molecular weight of 36,000 which contains 5.6% carbohydrate. It causes platelet aggregation, release of platelet serotonin, and activation of factor XIII. The most sensitive substrate for the amidolytic activity of thrombocytin was Tos-Gly-Pro-Arg-p-nitroanilide hydrochloride. The activity of thrombocytin on this substrate and on platelets was inhibited by diisopropyl fluorophosphate (DFP), soybean trypsin inhibitor, and several arginine chloromethyl ketones. Active site titration with nitrophenyl guanidinobenzoate demonstrated that approximately 86% of the preparation was in the active form. These experiments demonstrate the presence of serine and histidine in the active site of thrombocytin and suggest that thrombocytin is a classical serine protease with a platelet-activating activity similar to thrombin.

  6. Blockage of spontaneous Ca2+ oscillation causes cell death in intraerythrocitic Plasmodium falciparum.

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    Masahiro Enomoto

    Full Text Available Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Resistance to antimalarial drugs is a challenging problem in malaria control. Clinical malaria is associated with the proliferation and development of Plasmodium parasites in human erythrocytes. Especially, the development into the mature forms (trophozoite and schizont of Plasmodium falciparum (P. falciparum causes severe malaria symptoms due to a distinctive property, sequestration which is not shared by any other human malaria. Ca(2+ is well known to be a highly versatile intracellular messenger that regulates many different cellular processes. Cytosolic Ca(2+ increases evoked by extracellular stimuli are often observed in the form of oscillating Ca(2+ spikes (Ca(2+ oscillation in eukaryotic cells. However, in lower eukaryotic and plant cells the physiological roles and the molecular mechanisms of Ca(2+ oscillation are poorly understood. Here, we showed the observation of the inositol 1,4,5-trisphospate (IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum without any exogenous extracellular stimulation by using live cell fluorescence Ca(2+ imaging. Intraerythrocytic P. falciparum exhibited stage-specific Ca(2+ oscillations in ring form and trophozoite stages which were blocked by IP(3 receptor inhibitor, 2-aminoethyl diphenylborinate (2-APB. Analyses of parasitaemia and parasite size and electron micrograph of 2-APB-treated P. falciparum revealed that 2-APB severely obstructed the intraerythrocytic maturation, resulting in cell death of the parasites. Furthermore, we confirmed the similar lethal effect of 2-APB on the chloroquine-resistant strain of P. falciparum. To our best knowledge, we for the first time showed the existence of the spontaneous Ca(2+ oscillation in Plasmodium species and clearly demonstrated that IP(3-dependent spontaneous Ca(2+ oscillation in P. falciparum is critical for the development

  7. Imidazopyridine and Pyrazolopiperidine Derivatives as Novel Inhibitors of Serine Palmitoyl Transferase.

    Science.gov (United States)

    Genin, Michael J; Gonzalez Valcarcel, Isabel C; Holloway, William G; Lamar, Jason; Mosior, Marian; Hawkins, Eric; Estridge, Thomas; Weidner, Jeffrey; Seng, Thomas; Yurek, David; Adams, Lisa A; Weller, Jennifer; Reynolds, Vincent L; Brozinick, Joseph T

    2016-06-23

    To develop novel treatments for type 2 diabetes and dyslipidemia, we pursued inhibitors of serine palmitoyl transferase (SPT). To this end compounds 1 and 2 were developed as potent SPT inhibitors in vitro. 1 and 2 reduce plasma ceramides in rodents, have a slight trend toward enhanced insulin sensitization in DIO mice, and reduce triglycerides and raise HDL in cholesterol/cholic acid fed rats. Unfortunately these molecules cause a gastric enteropathy after chronic dosing in rats.

  8. Metabolism of serine in growing rats and chicks at various dietary protein levels

    International Nuclear Information System (INIS)

    Tanaka, Hideyuki; Yamaguchi, Michio; Kametaka, Masao

    1976-01-01

    The metabolic fate of the carbon skeleton of L-serine-U- 14 C has been investigated, in vivo and in vitro, in growing rats and chicks fed the diets with various protein calories percents (C %) at 410 kcal of metabolizable energy. The incorporation of 14 C into body protein at 12 hr after the injection of serine- 14 C was about 49% of the injected dose in rats fed the 10 or 15 PC% diet, though the value was reduced in rats fed lower and higher protein diets. The 14 CO 2 production was smaller in rats fed the 10 and 15 PC% diet, and it showed an inverse pattern to that of the 14 C incorporation into body protein. Urinary excretion of 14 C was higher in rats fed 10 and higher PC% diets, whose growth rate and net body protein retention were maximum. In contrast to the case of rats, the incorporation of 14 C into body protein of chicks at 6 hr after the injection was rather reduced in the 15 PC% group. The proportion of 14 C excreted as uric acid was remarkably increased above the 10 PC% group, and about 19% of the injected dose was recovered in the 50 PC% group. The catabolic rate of serine in the liver slices of rats and chicks was increased by high protein diets. These results support the concept that the nutritional significance of metabolism of the carbon skeleton of serine in growing rats and chicks is different from each other, especially at high protein diets. (auth.)

  9. ANTIOXIDANT EFFECTS OF L-SERINE AGAINST FATTY STREAK FORMATION IN HYPERCHOLESTEROLEMIC ANIMALS

    Directory of Open Access Journals (Sweden)

    Ahmad Movahedian

    2010-12-01

    Full Text Available   Abstract INTRODUCTION: Peroxidation of blood lipoproteins is regarded as a key event in the development of atherosclerosis. Evidence suggests that oxidative modification of amino acids in low-density lipoprotein (LDL particles leads to its convert into an atherogenic form, which is taken up by macrophages. Therefore the reduction of oxidative modification of lipoproteins by increasing plasma antioxidant capacity may prevent cardiovascular disease. methods: In this study, the antioxidant and anti-fatty streak effects of L-serine were investigated in hypercholesterolemic rabbits. Rabbits were randomly divided into three groups which were fed high-cholesterol diet (hypercholesterolemic control group, high-cholesterol + L-serine diet (treatment group, and normal diet (control for twelve weeks and then blood samples were obtained to measure plasma cholesterol, triglyceride (TG, high-density lipoprotein (HDL, low-density lipoprotein (LDL, antioxidant capacity (AC, malondialdehyde (MDA, and conjugated dienes (CDS. Right and left coronary arteries were also obtained for histological evaluation. results: No significant difference was observed in plasma cholesterol, TG, HDL, LDL and CDS levels between treatment and hypercholesterolemic control groups (P>0.05. The levels of plasma MDA and AC were 0.29‌ µM and 56%, respectively in the treatment group which showed a significant change in comparison with hypercholesterolemic control groups (P<0.05. The mean size of produced fatty streak also showed significant reduction in the treatment group compared to the hypercholesterolemic group (P<0.05. CONCLUSIONS: The results showed that L-serine has antioxidant and anti-fatty streak effects without any influence on plasma lipid levels in hypercholesterolemic rabbits.     Keywords: Atherosclerosis, cholesterol, L-serine, antioxidant, lipids, fatty streak.

  10. A Clostridium difficile alanine racemase affects spore germination and accommodates serine as a substrate.

    Science.gov (United States)

    Shrestha, Ritu; Lockless, Steve W; Sorg, Joseph A

    2017-06-23

    Clostridium difficile has become one of the most common bacterial pathogens in hospital-acquired infections in the United States. Although C. difficile is strictly anaerobic, it survives in aerobic environments and transmits between hosts via spores. C. difficile spore germination is triggered in response to certain bile acids and glycine. Although glycine is the most effective co-germinant, other amino acids can substitute with varying efficiencies. Of these, l-alanine is an effective co-germinant and is also a germinant for most bacterial spores. Many endospore-forming bacteria embed alanine racemases into their spore coats, and these enzymes are thought to convert the l-alanine germinant into d-alanine, a spore germination inhibitor. Although the C. difficile Alr2 racemase is the sixth most highly expressed gene during C. difficile spore formation, a previous study reported that Alr2 has little to no role in germination of C. difficile spores in rich medium. Here, we hypothesized that Alr2 could affect C. difficile l-alanine-induced spore germination in a defined medium. We found that alr2 mutant spores more readily germinate in response to l-alanine as a co-germinant. Surprisingly, d-alanine also functioned as a co-germinant. Moreover, we found that Alr2 could interconvert l- and d-serine and that Alr2 bound to l- and d-serine with ∼2-fold weaker affinity to that of l- and d-alanine. Finally, we demonstrate that l- and d-serine are also co-germinants for C. difficile spores. These results suggest that C. difficile spores can respond to a diverse set of amino acid co-germinants and reveal that Alr2 can accommodate serine as a substrate. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Mutations in serine protease inhibitor Kazal type 1 are strongly associated with chronic pancreatitis

    OpenAIRE

    Drenth, J P H; te Morsche, R; Jansen, J B M J

    2002-01-01

    Background: Although chronic pancreatitis is associated with risk factors such as alcoholism, hyperparathyroidism, and hypertriglyceridaemia, little is known of the actual aetiology of the disease. It is thought that inappropriate activation of trypsinogen causes pancreatitis, and indeed in cases of hereditary pancreatitis mutations of cationic trypsinogen (PRSS1) have been described. As serine protease inhibitor Kazal type 1 (SPINK1) is a potent natural inhibitor of pancreatic trypsin activi...

  12. Thermophysical property characterization of aqueous amino acid salt solution containing serine

    International Nuclear Information System (INIS)

    Navarro, Shanille S.; Leron, Rhoda B.; Soriano, Allan N.; Li, Meng-Hui

    2014-01-01

    Highlights: • Thermophysical properties of aqueous potassium and sodium salt solutions of serine were studied. • Density, viscosity, refractive index and electrolytic conductivity of the solution were measured. • The concentrations of amino acid salt ranges from x 1 = 0.009 to 0.07. • The temperature range studied was (298.15 to 343.15) K. • The measured data were represented satisfactorily by using the applied correlations. - Abstract: Thermophysical property characterization of aqueous potassium and sodium salt solutions containing serine was conducted in this study; specifically the system’s density, refractive index, electrical conductivity, and viscosity. Measurements were obtained over a temperature range of (298.15 to 343.15) K and at normal atmospheric pressure. Composition range from x 1 = 0.009 to 0.07 for aqueous potassium and sodium salt solutions containing serine was used. The sensitivity of the system’s thermophysical properties on temperature and composition variation were discussed and correlated based on the equations proposed for room temperature ionic liquids. The density, viscosity, and refractive index measurements of the aqueous systems were found to decrease as the temperature increases at fixed concentration and the values increase as the salt concentration increases (water composition decreases) at fixed temperature. Whereas, a different trend was observed for the electrical conductivity data; at fixed concentration, the conductivity values increase as the temperature increases and at fixed temperature, its value generally increases as the salt concentration increases but only to a certain level (specific concentration) wherein the conductivity of the solution starts to decrease when the concentration of the salt is further increased. Calculation results show that the applied models were satisfactory in representing the measured properties in the aqueous amino acid salt solution containing serine

  13. Evidence for possible involvement of an elastolytic serine protease in aspergillosis.

    OpenAIRE

    Kolattukudy, P E; Lee, J D; Rogers, L M; Zimmerman, P; Ceselski, S; Fox, B; Stein, B; Copelan, E A

    1993-01-01

    A number of isolates of Aspergillus fumigatus obtained from the hospital environment produced extracellular elastolytic activity. This activity was found to be catalyzed by a single 33-kDa protein which was purified and characterized to be a serine protease. A. fumigatus, when grown on the insoluble structural material obtained from murine and bovine lung, produced the same extracellular 33-kDa elastolytic protease, indicating that this enzyme is likely to be produced when the organism infect...

  14. The Contribution of Serine 194 Phosphorylation to Steroidogenic Acute Regulatory Protein Function

    OpenAIRE

    Sasaki, Goro; Zubair, Mohamad; Ishii, Tomohiro; Mitsui, Toshikatsu; Hasegawa, Tomonobu; Auchus, Richard J.

    2014-01-01

    The steroidogenic acute regulatory protein (StAR) facilitates the delivery of cholesterol to the inner mitochondrial membrane, where the cholesterol side-chain cleavage enzyme catalyzes the initial step of steroid hormone biosynthesis. StAR was initially identified in adrenocortical cells as a phosphoprotein, the expression and phosphorylation of which were stimulated by corticotropin. A number of in vitro studies have implicated cAMP-dependent phosphorylation at serine 194 (S194, S195 in hum...

  15. Serine racemase is expressed in islets and contributes to the regulation of glucose homeostasis.

    Science.gov (United States)

    Lockridge, Amber D; Baumann, Daniel C; Akhaphong, Brian; Abrenica, Alleah; Miller, Robert F; Alejandro, Emilyn U

    2016-11-01

    NMDA receptors (NMDARs) have recently been discovered as functional regulators of pancreatic β-cell insulin secretion. While these excitatory receptor channels have been extensively studied in the brain for their role in synaptic plasticity and development, little is known about how they work in β-cells. In neuronal cells, NMDAR activation requires the simultaneous binding of glutamate and a rate-limiting co-agonist, such as D-serine. D-serine levels and availability in most of the brain rely on endogenous synthesis by the enzyme serine racemase (Srr). Srr transcripts have been reported in human and mouse islets but it is not clear whether Srr is functionally expressed in β-cells or what its role in the pancreas might be. In this investigation, we reveal that Srr protein is highly expressed in primary human and mouse β-cells. Mice with whole body deletion of Srr (Srr KO) show improved glucose tolerance through enhanced insulin secretory capacity, possibly through Srr-mediated alterations in islet NMDAR expression and function. We observed elevated insulin sensitivity in some animals, suggesting Srr metabolic regulation in other peripheral organs as well. Srr expression in neonatal and embryonic islets, and adult deficits in Srr KO pancreas weight and islet insulin content, point toward a potential role for Srr in pancreatic development. These data reveal the first evidence that Srr may regulate glucose homeostasis in peripheral tissues and provide circumstantial evidence that D-serine may be an endogenous islet NMDAR co-agonist in β-cells.

  16. Impact of Serine/Threonine Protein Kinases on the Regulation of Sporulation in Bacillus subtilis.

    Science.gov (United States)

    Pompeo, Frédérique; Foulquier, Elodie; Galinier, Anne

    2016-01-01

    Bacteria possess many kinases that catalyze phosphorylation of proteins on diverse amino acids including arginine, cysteine, histidine, aspartate, serine, threonine, and tyrosine. These protein kinases regulate different physiological processes in response to environmental modifications. For example, in response to nutritional stresses, the Gram-positive bacterium Bacillus subtilis can differentiate into an endospore; the initiation of sporulation is controlled by the master regulator Spo0A, which is activated by phosphorylation. Spo0A phosphorylation is carried out by a multi-component phosphorelay system. These phosphorylation events on histidine and aspartate residues are labile, highly dynamic and permit a temporal control of the sporulation initiation decision. More recently, another kind of phosphorylation, more stable yet still dynamic, on serine or threonine residues, was proposed to play a role in spore maintenance and spore revival. Kinases that perform these phosphorylation events mainly belong to the Hanks family and could regulate spore dormancy and spore germination. The aim of this mini review is to focus on the regulation of sporulation in B. subtilis by these serine and threonine phosphorylation events and the kinases catalyzing them.

  17. Serine Protease Variants Encoded by Echis ocellatus Venom Gland cDNA: Cloning and Sequencing Analysis

    Directory of Open Access Journals (Sweden)

    S. S. Hasson

    2010-01-01

    Full Text Available Envenoming by Echis saw-scaled viper is the leading cause of death and morbidity in Africa due to snake bite. Despite its medical importance, there have been few investigations into the toxin composition of the venom of this viper. Here, we report the cloning of cDNA sequences encoding four groups or isoforms of the haemostasis-disruptive Serine protease proteins (SPs from the venom glands of Echis ocellatus. All these SP sequences encoded the cysteine residues scaffold that form the 6-disulphide bonds responsible for the characteristic tertiary structure of venom serine proteases. All the Echis ocellatus EoSP groups showed varying degrees of sequence similarity to published viper venom SPs. However, these groups also showed marked intercluster sequence conservation across them which were significantly different from that of previously published viper SPs. Because viper venom SPs exhibit a high degree of sequence similarity and yet exert profoundly different effects on the mammalian haemostatic system, no attempt was made to assign functionality to the new Echis ocellatus EoSPs on the basis of sequence alone. The extraordinary level of interspecific and intergeneric sequence conservation exhibited by the Echis ocellatus EoSPs and analogous serine proteases from other viper species leads us to speculate that antibodies to representative molecules should neutralise (that we will exploit, by epidermal DNA immunization the biological function of this important group of venom toxins in vipers that are distributed throughout Africa, the Middle East, and the Indian subcontinent.

  18. Assessment and partial purification of serine protease inhibitors from Rhipicephalus (Boophilus annulatuslarvae

    Directory of Open Access Journals (Sweden)

    Sedigheh Nabian

    Full Text Available Ticks are rich sources of serine protease inhibitors, particularly those that prevent blood clotting and inflammatory responses during blood feeding. The tick Rhipicephalus (Boophlus annulatusis an important ectoparasite of cattle. The aims of this study were to characterize and purify the serine protease inhibitors present in R. (B. annulatus larval extract. The inhibitors were characterized by means of one and two-dimensional reverse zymography, and purified using affinity chromatography on a trypsin-Sepharose column. The analysis on one and two-dimensional reverse zymography of the larval extract showed trypsin inhibitory activity at between 13 and 40 kDa. Through non-reducing SDS-PAGE and reverse zymography for proteins purified by trypsin-Sepharose affinity chromatography, some protein bands with molecular weights between 13 and 34 kDa were detected. Western blotting showed that five protein bands at 48, 70, 110, 130 and 250 kDa reacted positively with immune serum, whereas there was no positive reaction in the range of 13-40 kDa. Serine protease inhibitors from R. (B. annulatus have anti-trypsin activity similar to inhibitors belonging to several other hard tick species, thus suggesting that these proteins may be useful as targets in anti-tick vaccines.

  19. The C-terminal sequence of several human serine proteases encodes host defense functions.

    Science.gov (United States)

    Kasetty, Gopinath; Papareddy, Praveen; Kalle, Martina; Rydengård, Victoria; Walse, Björn; Svensson, Bo; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

    2011-01-01

    Serine proteases of the S1 family have maintained a common structure over an evolutionary span of more than one billion years, and evolved a variety of substrate specificities and diverse biological roles, involving digestion and degradation, blood clotting, fibrinolysis and epithelial homeostasis. We here show that a wide range of C-terminal peptide sequences of serine proteases, particularly from the coagulation and kallikrein systems, share characteristics common with classical antimicrobial peptides of innate immunity. Under physiological conditions, these peptides exert antimicrobial effects as well as immunomodulatory functions by inhibiting macrophage responses to bacterial lipopolysaccharide. In mice, selected peptides are protective against lipopolysaccharide-induced shock. Moreover, these S1-derived host defense peptides exhibit helical structures upon binding to lipopolysaccharide and also permeabilize liposomes. The results uncover new and fundamental aspects on host defense functions of serine proteases present particularly in blood and epithelia, and provide tools for the identification of host defense molecules of therapeutic interest. Copyright © 2011 S. Karger AG, Basel.

  20. Cross-phosphorylation of bacterial serine/threonine and tyrosine protein kinases on key regulatory residues

    Directory of Open Access Journals (Sweden)

    Lei eShi

    2014-09-01

    Full Text Available Bacteria possess protein serine/threonine and tyrosine kinases which resemble eukaryal kinases in their capacity to phosphorylate multiple substrates. We hypothesized that the analogy might extend further, and bacterial kinases may also undergo mutual phosphorylation and activation, which is currently considered as a hallmark of eukaryal kinase networks. In order to test this hypothesis, we explored the capacity of all members of four different classes of serine/threonine and tyrosine kinases present in the firmicute model organism Bacillus subtilis to phosphorylate each other in vitro and interact with each other in vivo. The interactomics data suggested a high degree of connectivity among all types of kinases, while phosphorylation assays revealed equally wide-spread cross-phosphorylation events. Our findings suggest that the Hanks-type kinases PrkC, PrkD and YabT exhibit the highest capacity to phosphorylate other B. subtilis kinases, while the BY-kinase PtkA and the two-component-like kinases RsbW and SpoIIAB show the highest propensity to be phosphorylated by other kinases. Analysis of phosphorylated residues on several selected recipient kinases suggests that most cross-phosphorylation events concern key regulatory residues. Therefore, cross-phosphorylation events are very likely to influence the capacity of recipient kinases to phosphorylate substrates downstream in the signal transduction cascade. We therefore conclude that bacterial serine/threonine and tyrosine kinases probably engage in a network-type behavior previously described only in eukaryal cells.

  1. Histone H3 Serine 28 Is Essential for Efficient Polycomb-Mediated Gene Repression in Drosophila

    Directory of Open Access Journals (Sweden)

    Philip Yuk Kwong Yung

    2015-06-01

    Full Text Available Trimethylation at histone H3K27 is central to the polycomb repression system. Juxtaposed to H3K27 is a widely conserved phosphorylatable serine residue (H3S28 whose function is unclear. To assess the importance of H3S28, we generated a Drosophila H3 histone mutant with a serine-to-alanine mutation at position 28. H3S28A mutant cells lack H3S28ph on mitotic chromosomes but support normal mitosis. Strikingly, all methylation states of H3K27 drop in H3S28A cells, leading to Hox gene derepression and to homeotic transformations in adult tissues. These defects are not caused by active H3K27 demethylation nor by the loss of H3S28ph. Biochemical assays show that H3S28A nucleosomes are a suboptimal substrate for PRC2, suggesting that the unphosphorylated state of serine 28 is important for assisting in the function of polycomb complexes. Collectively, our data indicate that the conserved H3S28 residue in metazoans has a role in supporting PRC2 catalysis.

  2. A New Bacillus licheniformis Mutant Strain Producing Serine Protease Efficient for Hvdrolvqis of Sov Meal Proteins.

    Science.gov (United States)

    Kostyleva, E V; Sereda, A S; Velikoretskaya, I A; Nefedova, L I; Sharikov, A Yu; Tsurikova, N V; Lobanov, N S; Semenova, M V; Sinitsyn, A P

    2016-07-01

    Induced mutagenesis with y-irradiation of the industrial strain Bacillus licheniformis-60 VKM B-2366,D was used to obtain a new highly active producer of an extracellular serine protease, Bacillus licheni- formis7 145. Samples of dry.concentrated preparations of serine protease produced by the original and mutant strains were obtained, and identity of their protein composition was'established. Alkaline serine protease sub- tilisin DY was the main component of the preparations. The biochemical and physicochemical properties of the Protolkheterm-145 enzyme preparation obtained from the mutant strain were studied. It exhibited pro- teolytic activity (1.5 times higher than the preparation from the initial strain) within broad ranges of pH (5- 11) and temperature (30-70'C).-Efficient hydrolysis of extruded soy meal protein at high concentrations (2 to 50%) in-the reaction mixture was.the main advantage of the Protolikheterm 145 preparation. Compared to,. the preparation obtained using the initial strain, the new preparation with increased proteolytic-activity pro- vided for more complete hydrolysis of the main non-nutritious soy,proteins.(glycinin and 0-conglycinin) with the yield of soluble protein increased by 19-28%, which decreased the cost of bioconversion of the protein- aceous material and indicated promise of the new preparation in resource-saving technologies for processing soy meals and cakes.

  3. Change in activity of serine palmitoyltransferase affects sensitivity to syringomycin E in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Toume, Moeko; Tani, Motohiro

    2014-09-01

    Syringomycin E is a cyclic lipodepsipeptide produced by strains of the plant bacterium Pseudomonas syringae pv. syringae. Genetic studies involving the yeast Saccharomyces cerevisiae have revealed that complex sphingolipids play important roles in the action of syringomycin E. Here, we found a novel mutation that confers resistance to syringomycin E on yeast; that is, a deletion mutant of ORM1 and ORM2, which encode negative regulators of serine palmitoyltransferase catalyzing the initial step of sphingolipid biosynthesis, exhibited resistance to syringomycin E. On the contrary, overexpression of Orm2 resulted in high sensitivity to the toxin. Moreover, overexpression of Lcb1 and Lcb2, catalytic subunits of serine palmitoyltransferase, causes resistance to the toxin, whereas partial repression of expression of Lcb1 had the opposite effect. Partial reduction of complex sphingolipids by repression of expression of Aur1, an inositol phosphorylceramide synthase, also resulted in high sensitivity to the toxin. These results suggested that an increase in sphingolipid biosynthesis caused by a change in the activity of serine palmitoyltransferase causes resistance to syringomycin E. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  4. Characterization of a serine protease-mediated cell death program activated in human leukemia cells

    International Nuclear Information System (INIS)

    O'Connell, A.R.; Holohan, C.; Torriglia, A.; Lee, B.F.; Stenson-Cox, C.

    2006-01-01

    Tightly controlled proteolysis is a defining feature of apoptosis and caspases are critical in this regard. Significant roles for non-caspase proteases in cell death have been highlighted. Staurosporine causes a rapid induction of apoptosis in virtually all mammalian cell types. Numerous studies demonstrate that staurosporine can activate cell death under caspase-inhibiting circumstances. The aim of this study was to investigate the proteolytic mechanisms responsible for cell death under these conditions. To that end, we show that inhibitors of serine proteases can delay cell death in one such system. Furthermore, through profiling of proteolytic activation, we demonstrate, for the first time, that staurosporine activates a chymotrypsin-like serine protease-dependent cell death in HL-60 cells independently, but in parallel with the caspase controlled systems. Features of the serine protease-mediated system include cell shrinkage and apoptotic morphology, regulation of caspase-3, altered nuclear morphology, generation of an endonuclease and DNA degradation. We also demonstrate a staurosporine-induced activation of a putative 16 kDa chymotrypsin-like protein during apoptosis

  5. Selection of Plasmodium falciparum Multidrug Resistance Gene 1 Alleles in Asexual Stages and Gametocytes by Artemether-Lumefantrine in Nigerian Children with Uncomplicated Falciparum Malaria ▿

    Science.gov (United States)

    Happi, C. T.; Gbotosho, G. O.; Folarin, O. A.; Sowunmi, A.; Hudson, T.; O'Neil, M.; Milhous, W.; Wirth, D. F.; Oduola, A. M. J.

    2009-01-01

    We assessed Plasmodium falciparum mdr1 (Pfmdr1) gene polymorphisms and copy numbers as well as P. falciparum Ca2+ ATPase (PfATPase6) gene polymorphisms in 90 Nigerian children presenting with uncomplicated falciparum malaria and enrolled in a study of the efficacy of artemether-lumefantrine (AL). The nested PCR-restriction fragment length polymorphism and the quantitative real-time PCR methodologies were used to determine the alleles of the Pfmdr1 and PfATPase6 genes and the Pfmdr1 copy number variation, respectively, in patients samples collected prior to treatment and at the reoccurrence of parasites during a 42-day follow-up. The Pfmdr1 haplotype 86N-184F-1246D was significantly associated (P copy of the Pfmdr1 gene and the wild-type allele (L89) at codon 89 of the PfATPase6 gene. These findings suggest that polymorphisms in the Pfmdr1 gene are under AL selection pressure. Pfmdr1 polymorphisms may result in reduction in the therapeutic efficacy of this newly adopted combination treatment for uncomplicated falciparum malaria in Saharan countries of Africa. PMID:19075074

  6. Selection of Plasmodium falciparum multidrug resistance gene 1 alleles in asexual stages and gametocytes by artemether-lumefantrine in Nigerian children with uncomplicated falciparum malaria.

    Science.gov (United States)

    Happi, C T; Gbotosho, G O; Folarin, O A; Sowunmi, A; Hudson, T; O'Neil, M; Milhous, W; Wirth, D F; Oduola, A M J

    2009-03-01

    We assessed Plasmodium falciparum mdr1 (Pfmdr1) gene polymorphisms and copy numbers as well as P. falciparum Ca(2+) ATPase (PfATPase6) gene polymorphisms in 90 Nigerian children presenting with uncomplicated falciparum malaria and enrolled in a study of the efficacy of artemether-lumefantrine (AL). The nested PCR-restriction fragment length polymorphism and the quantitative real-time PCR methodologies were used to determine the alleles of the Pfmdr1 and PfATPase6 genes and the Pfmdr1 copy number variation, respectively, in patients samples collected prior to treatment and at the reoccurrence of parasites during a 42-day follow-up. The Pfmdr1 haplotype 86N-184F-1246D was significantly associated (P copy of the Pfmdr1 gene and the wild-type allele (L89) at codon 89 of the PfATPase6 gene. These findings suggest that polymorphisms in the Pfmdr1 gene are under AL selection pressure. Pfmdr1 polymorphisms may result in reduction in the therapeutic efficacy of this newly adopted combination treatment for uncomplicated falciparum malaria in Saharan countries of Africa.

  7. FBXO22 Protein Is Required for Optimal Synthesis of the N-Methyl-d-Aspartate (NMDA) Receptor Coagonist d-Serine

    DEFF Research Database (Denmark)

    Dikopoltsev, Elena; Foltyn, Veronika N; Zehl, Martin

    2014-01-01

    d-Serine is a physiological activator of NMDA receptors (NMDARs) in the nervous system that mediates several NMDAR-mediated processes ranging from normal neurotransmission to neurodegeneration. d-Serine is synthesized from l-serine by serine racemase (SR), a brain-enriched enzyme. However, little......, SR interacts preferentially with free FBXO22 species. In vivo ubiquitination and SR half-life determination indicate that FBXO22 does not target SR to the proteasome system. FBXO22 primarily affects SR subcellular localization and seems to increase d-serine synthesis by preventing the association...... is known about the regulation of d-serine synthesis. We now demonstrate that the F-box only protein 22 (FBXO22) interacts with SR and is required for optimal d-serine synthesis in cells. Although FBXO22 is classically associated with the ubiquitin system and is recruited to the Skip1-Cul1-F-box E3 complex...

  8. Structural basis of metallo-β-lactamase, serine-β-lactamase and penicillin-binding protein inhibition by cyclic boronates

    Science.gov (United States)

    Brem, Jürgen; Cain, Ricky; Cahill, Samuel; McDonough, Michael A.; Clifton, Ian J.; Jiménez-Castellanos, Juan-Carlos; Avison, Matthew B.; Spencer, James; Fishwick, Colin W. G.; Schofield, Christopher J.

    2016-08-01

    β-Lactamases enable resistance to almost all β-lactam antibiotics. Pioneering work revealed that acyclic boronic acids can act as `transition state analogue' inhibitors of nucleophilic serine enzymes, including serine-β-lactamases. Here we report biochemical and biophysical analyses revealing that cyclic boronates potently inhibit both nucleophilic serine and zinc-dependent β-lactamases by a mechanism involving mimicking of the common tetrahedral intermediate. Cyclic boronates also potently inhibit the non-essential penicillin-binding protein PBP 5 by the same mechanism of action. The results open the way for development of dual action inhibitors effective against both serine- and metallo-β-lactamases, and which could also have antimicrobial activity through inhibition of PBPs.

  9. Apical serine protease activity is necessary for assembly of a high-resistance renal collecting duct epithelium

    DEFF Research Database (Denmark)

    Steensgaard, Mette; Svenningsen, Per; Tinning, Anne R

    2010-01-01

    Abstract AIM: We hypothesized that the serine protease prostasin is necessary for differentiation of a high resistance renal collecting duct epithelium governed by glucocorticoid. METHODS: Postnatal rat kidney and adult human kidney was used to study expression and localization of prostasin......-cadherin distribution did not change. CONCLUSION: Apical, GPI-anchored, lipid raft-associated serine protease activity, compatible with prostasin, is necessary for development of a high-resistance collecting duct epithelium....

  10. Fluorescently labeled inhibitors detect localized serine protease activities in Drosophila melanogaster pole cells, embryos, and ovarian egg chambers

    DEFF Research Database (Denmark)

    Jakobsen, Rasmus Kragh; Ono, S.; Powers, J. C.

    2005-01-01

    processes that they mediate. Until only recently, the tools to conveniently address the question of where and when serine proteases are active within complex tissues have been lacking. In order to detect spatially restricted serine protease activities in Drosophila embryos and ovaries we introduce...... activity localized to the oocyte-somatic follicle cell interface of the developing egg chamber. Our results suggest that this technique holds promise to identify new spatially restricted activities in adult Drosophila tissues and developing embryos....

  11. Genetic diversity and population structure of Plasmodium falciparum in Thailand, a low transmission country.

    Science.gov (United States)

    Pumpaibool, Tepanata; Arnathau, Céline; Durand, Patrick; Kanchanakhan, Naowarat; Siripoon, Napaporn; Suegorn, Aree; Sitthi-Amorn, Chitr; Renaud, François; Harnyuttanakorn, Pongchai

    2009-07-14

    The population structure of the causative agents of human malaria, Plasmodium sp., including the most serious agent Plasmodium falciparum, depends on the local epidemiological and demographic situations, such as the incidence of infected people, the vector transmission intensity and migration of inhabitants (i.e. exchange between sites). Analysing the structure of P. falciparum populations at a large scale, such as continents, or with markers that are subject to non-neutral selection, can lead to a masking and misunderstanding of the effective process of transmission. Thus, knowledge of the genetic structure and organization of P. falciparum populations in a particular area with neutral genetic markers is needed to understand which epidemiological factors should be targeted for disease control. Limited reports are available on the population genetic diversity and structure of P. falciparum in Thailand, and this is of particular concern at the Thai-Myanmar and Thai-Cambodian borders, where there is a reported high resistance to anti-malarial drugs, for example mefloquine, with little understanding of its potential gene flow. The diversity and genetic differentiation of P. falciparum populations were analysed using 12 polymorphic apparently neutral microsatellite loci distributed on eight of the 14 different chromosomes. Samples were collected from seven provinces in the western, eastern and southern parts of Thailand. A strong difference in the nuclear genetic structure was observed between most of the assayed populations. The genetic diversity was comparable to the intermediate level observed in low P. falciparum transmission areas (average HS = 0.65 +/- 0.17), where the lowest is observed in South America and the highest in Africa. However, uniquely the Yala province, had only a single multilocus genotype present in all samples, leading to a strong geographic differentiation when compared to the other Thai populations during this study. Comparison of the genetic

  12. Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number.

    Science.gov (United States)

    Price, Ric N; Uhlemann, Anne-Catrin; Brockman, Alan; McGready, Rose; Ashley, Elizabeth; Phaipun, Lucy; Patel, Rina; Laing, Kenneth; Looareesuwan, Sornchai; White, Nicholas J; Nosten, François; Krishna, Sanjeev

    The borders of Thailand harbour the world's most multidrug resistant Plasmodium falciparum parasites. In 1984 mefloquine was introduced as treatment for uncomplicated falciparum malaria, but substantial resistance developed within 6 years. A combination of artesunate with mefloquine now cures more than 95% of acute infections. For both treatment regimens, the underlying mechanisms of resistance are not known. The relation between polymorphisms in the P falciparum multidrug resistant gene 1 (pfmdr1) and the in-vitro and in-vivo responses to mefloquine were assessed in 618 samples from patients with falciparum malaria studied prospectively over 12 years. pfmdr1 copy number was assessed by a robust real-time PCR assay. Single nucleotide polymorphisms of pfmdr1, P falciparum chloroquine resistance transporter gene (pfcrt) and P falciparum Ca2+ ATPase gene (pfATP6) were assessed by PCR-restriction fragment length polymorphism. Increased copy number of pfmdr1 was the most important determinant of in-vitro and in-vivo resistance to mefloquine, and also to reduced artesunate sensitivity in vitro. In a Cox regression model with control for known confounders, increased pfmdr1 copy number was associated with an attributable hazard ratio (AHR) for treatment failure of 6.3 (95% CI 2.9-13.8, p<0.001) after mefloquine monotherapy and 5.4 (2.0-14.6, p=0.001) after artesunate-mefloquine therapy. Single nucleotide polymorphisms in pfmdr1 were associated with increased mefloquine susceptibility in vitro, but not in vivo. Amplification in pfmdr1 is the main cause of resistance to mefloquine in falciparum malaria. Multidrug resistant P falciparum malaria is common in southeast Asia, but difficult to identify and treat. Genes that encode parasite transport proteins maybe involved in export of drugs and so cause resistance. In this study we show that increase in copy number of pfmdr1, a gene encoding a parasite transport protein, is the best overall predictor of treatment failure with

  13. ABO Blood Groups Influence Macrophage-mediated Phagocytosis of Plasmodium falciparum-infected Erythrocytes

    Science.gov (United States)

    Branch, Donald R.; Hult, Annika K.; Olsson, Martin L.; Liles, W. Conrad; Cserti-Gazdewich, Christine M.; Kain, Kevin C.

    2012-01-01

    Erythrocyte polymorphisms associated with a survival advantage to Plasmodium falciparum infection have undergone positive selection. There is a predominance of blood group O in malaria-endemic regions, and several lines of evidence suggest that ABO blood groups may influence the outcome of P. falciparum infection. Based on the hypothesis that enhanced innate clearance of infected polymorphic erythrocytes is associated with protection from severe malaria, we investigated whether P. falciparum-infected O erythrocytes are more efficiently cleared by macrophages than infected A and B erythrocytes. We show that human macrophages in vitro and mouse monocytes in vivo phagocytose P. falciparum-infected O erythrocytes more avidly than infected A and B erythrocytes and that uptake is associated with increased hemichrome deposition and high molecular weight band 3 aggregates in infected O erythrocytes. Using infected A1, A2, and O erythrocytes, we demonstrate an inverse association of phagocytic capacity with the amount of A antigen on the surface of infected erythrocytes. Finally, we report that enzymatic conversion of B erythrocytes to type as O before infection significantly enhances their uptake by macrophages to observed level comparable to that with infected O wild-type erythrocytes. These data provide the first evidence that ABO blood group antigens influence macrophage clearance of P. falciparum-infected erythrocytes and suggest an additional mechanism by which blood group O may confer resistance to severe malaria. PMID:23071435

  14. Biomarkers of Plasmodium falciparum infection during pregnancy in women living in northeastern Tanzania.

    Directory of Open Access Journals (Sweden)

    Stéphanie Boström

    Full Text Available In pregnant women, Plasmodium falciparum infections are an important cause of maternal morbidity as well as fetal and neonatal mortality. Erythrocytes infected by these malaria-causing parasites accumulate through adhesive interactions in placental intervillous spaces, thus evading detection in peripheral blood smears. Sequestered infected erythrocytes induce inflammation, offering the possibility of detecting inflammatory mediators in peripheral blood that could act as biomarkers of placental infection. In a longitudinal, prospective study in Tanzania, we quantified a range of different cytokines, chemokines and angiogenic factors in peripheral plasma samples, taken on multiple sequential occasions during pregnancy up to and including delivery, from P. falciparum-infected women and matched uninfected controls. The results show that during healthy, uninfected pregnancies the levels of most of the panel of molecules we measured were largely unchanged except at delivery. In women with P. falciparum, however, both comparative and longitudinal assessments consistently showed that the levels of IL-10 and IP-10 increased significantly whilst that of RANTES decreased significantly, regardless of gestational age at the time the infection was detected. ROC curve analysis indicated that a combination of increased IL-10 and IP-10 levels and decreased RANTES levels might be predictive of P. falciparum infections. In conclusion, our data suggest that host biomarkers in peripheral blood may represent useful diagnostic markers of P. falciparum infection during pregnancy, but placental histology results would need to be included to verify these findings.

  15. Bacillus thuringiensis Cry3Aa protoxin intoxication of Tenebrio molitor induces widespread changes in the expression of serine peptidase transcripts.

    Science.gov (United States)

    Oppert, Brenda; Martynov, Alexander G; Elpidina, Elena N

    2012-09-01

    The yellow mealworm, Tenebrio molitor, is a pest of stored grain products and is sensitive to the Bacillus thuringiensis (Bt) Cry3Aa toxin. As digestive peptidases are a determining factor in Cry toxicity and resistance, we evaluated the expression of peptidase transcripts in the midgut of T. molitor larvae fed either a control or Cry3Aa protoxin diet for 24 h (RNA-Seq), or in larvae exposed to the protoxin for 6, 12, or 24 h (microarrays). Cysteine peptidase transcripts (9) were similar to cathepsins B, L, and K, and their expression did not vary more than 2.5-fold in control and Cry3Aa-treated larvae. Serine peptidase transcripts (48) included trypsin, chymotrypsin and chymotrypsin-like, elastase 1-like, and unclassified serine peptidases, as well as homologs lacking functional amino acids. Highly expressed trypsin and chymotrypsin transcripts were severely repressed, and most serine peptidase transcripts were expressed 2- to 15-fold lower in Cry3Aa-treated larvae. Many serine peptidase and homolog transcripts were found only in control larvae. However, expression of a few serine peptidase transcripts was increased or found only in Cry3Aa-treated larvae. Therefore, Bt intoxication significantly impacted the expression of serine peptidases, potentially important in protoxin processing, while the insect maintained the production of critical digestive cysteine peptidases. Published by Elsevier Inc.

  16. Phosphorylation of SAF-A/hnRNP-U Serine 59 by Polo-Like Kinase 1 Is Required for Mitosis.

    Science.gov (United States)

    Douglas, Pauline; Ye, Ruiqiong; Morrice, Nicholas; Britton, Sébastien; Trinkle-Mulcahy, Laura; Lees-Miller, Susan P

    2015-08-01

    Scaffold attachment factor A (SAF-A), also called heterogenous nuclear ribonuclear protein U (hnRNP-U), is phosphorylated on serine 59 by the DNA-dependent protein kinase (DNA-PK) in response to DNA damage. Since SAF-A, DNA-PK catalytic subunit (DNA-PKcs), and protein phosphatase 6 (PP6), which interacts with DNA-PKcs, have all been shown to have roles in mitosis, we asked whether DNA-PKcs phosphorylates SAF-A in mitosis. We show that SAF-A is phosphorylated on serine 59 in mitosis, that phosphorylation requires polo-like kinase 1 (PLK1) rather than DNA-PKcs, that SAF-A interacts with PLK1 in nocodazole-treated cells, and that serine 59 is dephosphorylated by protein phosphatase 2A (PP2A) in mitosis. Moreover, cells expressing SAF-A in which serine 59 is mutated to alanine have multiple characteristics of aberrant mitoses, including misaligned chromosomes, lagging chromosomes, polylobed nuclei, and delayed passage through mitosis. Our findings identify serine 59 of SAF-A as a new target of both PLK1 and PP2A in mitosis and reveal that both phosphorylation and dephosphorylation of SAF-A serine 59 by PLK1 and PP2A, respectively, are required for accurate and timely exit from mitosis. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  17. Unlike pregnant adult women, pregnant adolescent girls cannot maintain glycine flux during late pregnancy because of decreased synthesis from serine.

    Science.gov (United States)

    Hsu, Jean W; Thame, Minerva M; Gibson, Raquel; Baker, Tameka M; Tang, Grace J; Chacko, Shaji K; Jackson, Alan A; Jahoor, Farook

    2016-03-14

    During pregnancy, glycine and serine become more important because they are the primary suppliers of methyl groups for the synthesis of fetal DNA, and more glycine is required for fetal collagen synthesis as pregnancy progresses. In an earlier study, we reported that glycine flux decreased by 39% from the first to the third trimester in pregnant adolescent girls. As serine is a primary precursor for glycine synthesis, the objective of this study was to measure and compare glycine and serine fluxes and inter-conversions in pregnant adolescent girls and adult women in the first and third trimesters. Measurements were made after an overnight fast by continuous intravenous infusions of 2H2-glycine and 15N-serine in eleven adolescent girls (17·4 (se 0·1) years of age) and in ten adult women (25·8 (se 0·5) years of age) for 4 h. Adolescent girls had significantly slower glycine flux and they made less glycine from serine in the third (Padolescent girls (P=0·04) and was significantly associated with third trimester glycine flux. These findings suggest that the pregnant adolescent cannot maintain glycine flux in late pregnancy compared with early pregnancy because of decreased synthesis from serine. It is possible that the inability to maintain glycine synthesis makes her fetus vulnerable to impaired cartilage synthesis, and thus linear growth.

  18. Decreased levels of free D-aspartic acid in the forebrain of serine racemase (Srr) knock-out mice.

    Science.gov (United States)

    Horio, Mao; Ishima, Tamaki; Fujita, Yuko; Inoue, Ran; Mori, Hisashi; Hashimoto, Kenji

    2013-05-01

    d-Serine, an endogenous co-agonist of the N-methyl-d-aspartate (NMDA) receptor is synthesized from l-serine by serine racemase (SRR). A previous study of Srr knockout (Srr-KO) mice showed that levels of d-serine in forebrain regions, such as frontal cortex, hippocampus, and striatum, but not cerebellum, of mutant mice are significantly lower than those of wild-type (WT) mice, suggesting that SRR is responsible for d-serine production in the forebrain. In this study, we attempted to determine whether SRR affects the level of other amino acids in brain tissue. We found that tissue levels of d-aspartic acid in the forebrains (frontal cortex, hippocampus and striatum) of Srr-KO mice were significantly lower than in WT mice, whereas levels of d-aspartic acid in the cerebellum were not altered. Levels of d-alanine, l-alanine, l-aspartic acid, taurine, asparagine, arginine, threonine, γ-amino butyric acid (GABA) and methionine, remained the same in frontal cortex, hippocampus, striatum and cerebellum of WT and mutant mice. Furthermore, no differences in d-aspartate oxidase (DDO) activity were detected in the forebrains of WT and Srr-KO mice. These results suggest that SRR and/or d-serine may be involved in the production of d-aspartic acid in mouse forebrains, although further detailed studies will be necessary to confirm this finding. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. [Congenital malaria due to Plasmodium falciparum and Plasmodium malariae].

    Science.gov (United States)

    Zenz, W; Trop, M; Kollaritsch, H; Reinthaler, F

    2000-05-19

    Increasing tourism and growing numbers of immigrants from malaria-endemic countries are leading to a higher importation rate of rare tropical disorders in European countries. We describe, to the best of our knowledge, the first case of connatal malaria in Austria. The patient is the first child of a 24 year old mother who was born in Ghana and immigrated to Austria one and a half years before delivery. She did not stay in an endemic region during this period and did not show fever or any other signs of malaria. The boy was healthy for the first six weeks of his life. In the 8th week of life he was admitted to our hospital due to persistent fever of unknown origin. On physical examination he showed only mild splenomegaly. Routine laboratory testing revealed mild hemolytic anemia with a hemoglobin value of 8.3 g/l. In the blood smear Plasmodium falciparum and Plasmodium malariae were detected. Oral therapy with quinine hydrochloride was successful and blood smears became negative for Plasmodia within 6 days. This case shows that congenital malaria can occur in children of clinically healthy women who were born in malaria-endemic areas even one and a half year after they have immigrated to non-endemic regions.

  20. Chromosome End Repair and Genome Stability in Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Susannah F. Calhoun

    2017-08-01

    Full Text Available The human malaria parasite Plasmodium falciparum replicates within circulating red blood cells, where it is subjected to conditions that frequently cause DNA damage. The repair of DNA double-stranded breaks (DSBs is thought to rely almost exclusively on homologous recombination (HR, due to a lack of efficient nonhomologous end joining. However, given that the parasite is haploid during this stage of its life cycle, the mechanisms involved in maintaining genome stability are poorly understood. Of particular interest are the subtelomeric regions of the chromosomes, which contain the majority of the multicopy variant antigen-encoding genes responsible for virulence and disease severity. Here, we show that parasites utilize a competitive balance between de novo telomere addition, also called “telomere healing,” and HR to stabilize chromosome ends. Products of both repair pathways were observed in response to DSBs that occurred spontaneously during routine in vitro culture or resulted from experimentally induced DSBs, demonstrating that both pathways are active in repairing DSBs within subtelomeric regions and that the pathway utilized was determined by the DNA sequences immediately surrounding the break. In combination, these two repair pathways enable parasites to efficiently maintain chromosome stability while also contributing to the generation of genetic diversity.

  1. Plasmodium falciparum erythrocyte invasion: combining function with immune evasion.

    Directory of Open Access Journals (Sweden)

    Gavin J Wright

    2014-03-01

    Full Text Available All the symptoms and pathology of malaria are caused by the intraerythrocytic stages of the Plasmodium parasite life cycle. Because Plasmodium parasites cannot replicate outside a host cell, their ability to recognize and invade erythrocytes is an essential step for both parasite survival and malaria pathogenesis. This makes invasion a conceptually attractive vaccine target, especially because it is one of the few stages when the parasite is directly exposed to the host humoral immune system. This apparent vulnerability, however, has been countered by the parasite, which has evolved sophisticated molecular mechanisms to evade the host immune response so that parasites asymptomatically replicate within immune individuals. These mechanisms include the expansion of parasite invasion ligands, resulting in multiple and apparently redundant invasion "pathways", highly polymorphic parasite surface proteins that are immunologically distinct, and parasite proteins which are poorly immunogenic. These formidable defences have so far thwarted attempts to develop an effective blood-stage vaccine, leading many to question whether there really is an exploitable chink in the parasite's immune evasion defences. Here, we review recent advances in the molecular understanding of the P. falciparum erythrocyte invasion field, discuss some of the challenges that have so far prevented the development of blood-stage vaccines, and conclude that the parasite invasion ligand RH5 represents an essential pinch point that might be vulnerable to vaccination.

  2. The dynamics of naturally acquired immunity to Plasmodium falciparum infection.

    Directory of Open Access Journals (Sweden)

    Mykola Pinkevych

    Full Text Available Severe malaria occurs predominantly in young children and immunity to clinical disease is associated with cumulative exposure in holoendemic settings. The relative contribution of immunity against various stages of the parasite life cycle that results in controlling infection and limiting disease is not well understood. Here we analyse the dynamics of Plasmodium falciparum malaria infection after treatment in a cohort of 197 healthy study participants of different ages in order to model naturally acquired immunity. We find that both delayed time-to-infection and reductions in asymptomatic parasitaemias in older age groups can be explained by immunity that reduces the growth of blood stage as opposed to liver stage parasites. We found that this mechanism would require at least two components - a rapidly acting strain-specific component, as well as a slowly acquired cross-reactive or general immunity to all strains. Analysis and modelling of malaria infection dynamics and naturally acquired immunity with age provides important insights into what mechanisms of immune control may be harnessed by malaria vaccine strategists.

  3. On the mechanism of chloroquine resistance in Plasmodium falciparum.

    KAUST Repository

    Chinappi, Mauro; Via, Allegra; Marcatili, Paolo; Tramontano, Anna

    2010-01-01

    Resistance to chloroquine of malaria strains is known to be associated with a parasite protein named PfCRT, the mutated form of which is able to reduce chloroquine accumulation in the digestive vacuole of the pathogen. Whether the protein mediates extrusion of the drug acting as a channel or as a carrier and which is the protonation state of its chloroquine substrate is the subject of a scientific debate. We present here an analytical approach that explores which combination of hypotheses on the mechanism of transport and the protonation state of chloroquine are consistent with available equilibrium experimental data. We show that the available experimental data are not, by themselves, sufficient to conclude whether the protein acts as a channel or as a transporter, which explains the origin of their different interpretation by different authors. Interestingly, though, each of the two models is only consistent with a subset of hypotheses on the protonation state of the transported molecule. The combination of these results with a sequence and structure analysis of PfCRT, which strongly suggests that the molecule is a carrier, indicates that the transported species is either or both the mono and di-protonated forms of chloroquine. We believe that our results, besides shedding light on the mechanism of chloroquine resistance in P. falciparum, have implications for the development of novel therapies against resistant malaria strains and demonstrate the usefulness of an approach combining systems biology strategies with structural bioinformatics and experimental data.

  4. Adaptation of Plasmodium falciparum to its transmission environment.

    Science.gov (United States)

    Rono, Martin K; Nyonda, Mary A; Simam, Joan J; Ngoi, Joyce M; Mok, Sachel; Kortok, Moses M; Abdullah, Abdullah S; Elfaki, Mohammed M; Waitumbi, John N; El-Hassan, Ibrahim M; Marsh, Kevin; Bozdech, Zbynek; Mackinnon, Margaret J

    2018-02-01

    Success in eliminating malaria will depend on whether parasite evolution outpaces control efforts. Here, we show that Plasmodium falciparum parasites (the deadliest of the species causing human malaria) found in low-transmission-intensity areas have evolved to invest more in transmission to new hosts (reproduction) and less in within-host replication (growth) than parasites found in high-transmission areas. At the cellular level, this adaptation manifests as increased production of reproductive forms (gametocytes) early in the infection at the expense of processes associated with multiplication inside red blood cells, especially membrane transport and protein trafficking. At the molecular level, this manifests as changes in the expression levels of genes encoding epigenetic and translational machinery. Specifically, expression levels of the gene encoding AP2-G-the transcription factor that initiates reproduction-increase as transmission intensity decreases. This is accompanied by downregulation and upregulation of genes encoding HDAC1 and HDA1-two histone deacetylases that epigenetically regulate the parasite's replicative and reproductive life-stage programmes, respectively. Parasites in reproductive mode show increased reliance on the prokaryotic translation machinery found inside the plastid-derived organelles. Thus, our dissection of the parasite's adaptive regulatory architecture has identified new potential molecular targets for malaria control.

  5. Harvest of Plasmodium falciparum merozoites from continuous culture.

    Science.gov (United States)

    Mrema, J E; Campbell, G H; Jaramillo, A L; Miranda, R; Rieckmann, K H

    1979-01-01

    Spontaneously released merozoites were harvested from cultures in which 42-90% of the erythrocytes had been infected with mature forms of Plasmodium falciparum at the start of incubation. The mature forms had been extracted from asynchronous cultures by the use of Ficoll and Plasmagel gradients. As the mature forms consisted of both trophozoites and schizonts, merozoites were released into the culture medium over a long period of time. The synchrony of merozoite release did not appear to be improved by prior exposure of parasites to sorbitol. Over this prolonged period of incubation, the yield of merozoites was disappointingly low in cultures containing 2.5% of erythrocytes. At erythrocyte concentrations of 0.01-0.25%, 3-10 times more merozoites were released into the medium; 0.4-2.3 merozoites per initial mature form were harvested over a 15-19-hour period. In addition to merozoites, contents of the culture medium included intact erythrocytes, ghost cells, and other cellular fragments. Only intact erythrocytes were effectively removed from the medium by simple or Ficoll gradient centrifugation. Merozoite preparations that are free from host cellular material are important in the development of a human malaria vaccine.

  6. Polyamine uptake by the intraerythrocytic malaria parasite, Plasmodium falciparum.

    Science.gov (United States)

    Niemand, J; Louw, A I; Birkholtz, L; Kirk, K

    2012-09-01

    Polyamines and the enzymes involved in their biosynthesis are present at high levels in rapidly proliferating cells, including cancer cells and protozoan parasites. Inhibition of polyamine biosynthesis in asexual blood-stage malaria parasites causes cytostatic arrest of parasite development under in vitro conditions, but does not cure infections in vivo. This may be due to replenishment of the parasite's intracellular polyamine pool via salvage of exogenous polyamines from the host. However, the mechanism(s) of polyamine uptake by the intraerythrocytic parasite are not well understood. In this study, the uptake of the polyamines, putrescine and spermidine, into Plasmodium falciparum parasites functionally isolated from their host erythrocyte was investigated using radioisotope flux techniques. Both putrescine and spermidine were taken up into isolated parasites via a temperature-dependent process that showed cross-competition between different polyamines. There was also some inhibition of polyamine uptake by basic amino acids. Inhibition of polyamine biosynthesis led to an increase in the total amount of putrescine and spermidine taken up from the extracellular medium. The uptake of putrescine and spermidine by isolated parasites was independent of extracellular Na(+) but increased with increasing external pH. Uptake also showed a marked dependence on the parasite's membrane potential, decreasing with membrane depolarization and increasing with membrane hyperpolarization. The data are consistent with polyamines being taken up into the parasite via an electrogenic uptake process, energised by the parasite's inwardly negative membrane potential. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  7. Genetic architecture of artemisinin-resistant Plasmodium falciparum

    Science.gov (United States)

    Miotto, Olivo; Amato, Roberto; Ashley, Elizabeth A; MacInnis, Bronwyn; Almagro-Garcia, Jacob; Amaratunga, Chanaki; Lim, Pharath; Mead, Daniel; Oyola, Samuel O; Dhorda, Mehul; Imwong, Mallika; Woodrow, Charles; Manske, Magnus; Stalker, Jim; Drury, Eleanor; Campino, Susana; Amenga-Etego, Lucas; Thanh, Thuy-Nhien Nguyen; Tran, Hien Tinh; Ringwald, Pascal; Bethell, Delia; Nosten, Francois; Phyo, Aung Pyae; Pukrittayakamee, Sasithon; Chotivanich, Kesinee; Chuor, Char Meng; Nguon, Chea; Suon, Seila; Sreng, Sokunthea; Newton, Paul N; Mayxay, Mayfong; Khanthavong, Maniphone; Hongvanthong, Bouasy; Htut, Ye; Han, Kay Thwe; Kyaw, Myat Phone; Faiz, Md Abul; Fanello, Caterina I; Onyamboko, Marie; Mokuolu, Olugbenga A; Jacob, Christopher G; Takala-Harrison, Shannon; Plowe, Christopher V; Day, Nicholas P; Dondorp, Arjen M; Spencer, Chris C A; McVean, Gilean; Fairhurst, Rick M; White, Nicholas J; Kwiatkowski, Dominic P

    2015-01-01

    We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population. PMID:25599401

  8. The periodicity of Plasmodium vivax and Plasmodium falciparum in Venezuela.

    Science.gov (United States)

    Grillet, María-Eugenia; El Souki, Mayida; Laguna, Francisco; León, José Rafael

    2014-01-01

    We investigated the periodicity of Plasmodium vivax and P. falciparum incidence in time-series of malaria data (1990-2010) from three endemic regions in Venezuela. In particular, we determined whether disease epidemics were related to local climate variability and regional climate anomalies such as the El Niño Southern Oscillation (ENSO). Malaria periodicity was found to exhibit unique features in each studied region. Significant multi-annual cycles of 2- to about 6-year periods were identified. The inter-annual variability of malaria cases was coherent with that of SSTs (ENSO), mainly at temporal scales within the 3-6 year periods. Additionally, malaria cases were intensified approximately 1 year after an El Niño event, a pattern that highlights the role of climate inter-annual variability in the epidemic patterns. Rainfall mediated the effect of ENSO on malaria locally. Particularly, rains from the last phase of the season had a critical role in the temporal dynamics of Plasmodium. The malaria-climate relationship was complex and transient, varying in strength with the region and species. By identifying temporal cycles of malaria we have made a first step in predicting high-risk years in Venezuela. Our findings emphasize the importance of analyzing high-resolution spatial-temporal data to better understand malaria transmission dynamics. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. On the mechanism of chloroquine resistance in Plasmodium falciparum.

    KAUST Repository

    Chinappi, Mauro

    2010-11-19

    Resistance to chloroquine of malaria strains is known to be associated with a parasite protein named PfCRT, the mutated form of which is able to reduce chloroquine accumulation in the digestive vacuole of the pathogen. Whether the protein mediates extrusion of the drug acting as a channel or as a carrier and which is the protonation state of its chloroquine substrate is the subject of a scientific debate. We present here an analytical approach that explores which combination of hypotheses on the mechanism of transport and the protonation state of chloroquine are consistent with available equilibrium experimental data. We show that the available experimental data are not, by themselves, sufficient to conclude whether the protein acts as a channel or as a transporter, which explains the origin of their different interpretation by different authors. Interestingly, though, each of the two models is only consistent with a subset of hypotheses on the protonation state of the transported molecule. The combination of these results with a sequence and structure analysis of PfCRT, which strongly suggests that the molecule is a carrier, indicates that the transported species is either or both the mono and di-protonated forms of chloroquine. We believe that our results, besides shedding light on the mechanism of chloroquine resistance in P. falciparum, have implications for the development of novel therapies against resistant malaria strains and demonstrate the usefulness of an approach combining systems biology strategies with structural bioinformatics and experimental data.

  10. Plasmodium falciparum dolichol phosphate mannose synthase represents a novel clade

    International Nuclear Information System (INIS)

    Shams-Eldin, Hosam; Santos de Macedo, Cristiana; Niehus, Sebastian; Dorn, Caroline; Kimmel, Juergen; Azzouz, Nahid; Schwarz, Ralph T.

    2008-01-01

    Dolichol phosphate mannose synthase (DPM) catalyzes the reaction between dolichol phosphate (Dol-P) and guanosine diphosphate mannose (GDP-Man) to form dolichol-phosphate-mannose (Dol-P-Man). This molecule acts as mannose donor for N-glycosylation and glycosylphosphatidylinositol (GPI) biosynthesis. The Plasmodium falciparum DPM1 (Pfdpm1) possesses a single predicted transmembrane region near the N-, but not the C-terminus. Here we show that the cloned Pfdpm1 gene failed to complement a Saccharomyces cerevisiae mutant indicating that the parasite gene does not belong to the baker's yeast group, as was previously assumed. Furthermore, Pfdpm1 was unable to complement a mouse mutant deficient in DPM but efficiently complements the Schizosaccharomyces pombe fission yeast mutant, indicating a difference between fission yeast and mammalian DPM genes. Therefore, we reanalyzed the hydrophobicity scales of all known DPMs and consequently reclassify the DPM clade into six major novel subgroups. Furthermore, we show that Pfdpm1 represents a unique enzyme among these subgroups

  11. The homeostasis of Plasmodium falciparum-infected red blood cells.

    Directory of Open Access Journals (Sweden)

    Jakob M A Mauritz

    2009-04-01

    Full Text Available The asexual reproduction cycle of Plasmodium falciparum, the parasite responsible for severe malaria, occurs within red blood cells. A merozoite invades a red cell in the circulation, develops and multiplies, and after about 48 hours ruptures the host cell, releasing 15-32 merozoites ready to invade new red blood cells. During this cycle, the parasite increases the host cell permeability so much that when similar permeabilization was simulated on uninfected red cells, lysis occurred before approximately 48 h. So how could infected cells, with a growing parasite inside, prevent lysis before the parasite has completed its developmental cycle? A mathematical model of the homeostasis of infected red cells suggested that it is the wasteful consumption of host cell hemoglobin that prevents early lysis by the progressive reduction in the colloid-osmotic pressure within the host (the colloid-osmotic hypothesis. However, two critical model predictions, that infected cells would swell to near prelytic sphericity and that the hemoglobin concentration would become progressively reduced, remained controversial. In this paper, we are able for the first time to correlate model predictions with recent experimental data in the literature and explore the fine details of the homeostasis of infected red blood cells during five model-defined periods of parasite development. The conclusions suggest that infected red cells do reach proximity to lytic rupture regardless of their actual volume, thus requiring a progressive reduction in their hemoglobin concentration to prevent premature lysis.

  12. Artemether-lumefantrine treatment of uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Kofoed, Poul-Erik

    2015-01-01

    BACKGROUND: Achieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the 'therapeutic' day 7 lumefantrine concentr......BACKGROUND: Achieving adequate antimalarial drug exposure is essential for curing malaria. Day 7 blood or plasma lumefantrine concentrations provide a simple measure of drug exposure that correlates well with artemether-lumefantrine efficacy. However, the 'therapeutic' day 7 lumefantrine......-lumefantrine for uncomplicated Plasmodium falciparum malaria, to define therapeutic day 7 lumefantrine concentrations and identify patient factors that substantially alter these concentrations. A systematic review of PubMed, Embase, Google Scholar, ClinicalTrials.gov and conference proceedings identified all relevant studies...... lumefantrine concentrations ≥200 ng/ml and high cure rates in most uncomplicated malaria patients. Three groups are at increased risk of treatment failure: very young children (particularly those underweight-for-age); patients with high parasitemias; and patients in very low transmission intensity areas...

  13. On the Mechanism of Chloroquine Resistance in Plasmodium falciparum

    Science.gov (United States)

    Marcatili, Paolo; Tramontano, Anna

    2010-01-01

    Resistance to chloroquine of malaria strains is known to be associated with a parasite protein named PfCRT, the mutated form of which is able to reduce chloroquine accumulation in the digestive vacuole of the pathogen. Whether the protein mediates extrusion of the drug acting as a channel or as a carrier and which is the protonation state of its chloroquine substrate is the subject of a scientific debate. We present here an analytical approach that explores which combination of hypotheses on the mechanism of transport and the protonation state of chloroquine are consistent with available equilibrium experimental data. We show that the available experimental data are not, by themselves, sufficient to conclude whether the protein acts as a channel or as a transporter, which explains the origin of their different interpretation by different authors. Interestingly, though, each of the two models is only consistent with a subset of hypotheses on the protonation state of the transported molecule. The combination of these results with a sequence and structure analysis of PfCRT, which strongly suggests that the molecule is a carrier, indicates that the transported species is either or both the mono and di-protonated forms of chloroquine. We believe that our results, besides shedding light on the mechanism of chloroquine resistance in P. falciparum, have implications for the development of novel therapies against resistant malaria strains and demonstrate the usefulness of an approach combining systems biology strategies with structural bioinformatics and experimental data. PMID:21124966

  14. Host factors that modify Plasmodium falciparum adhesion to endothelial receptors.

    Science.gov (United States)

    Mahamar, Almahamoudou; Attaher, Oumar; Swihart, Bruce; Barry, Amadou; Diarra, Bacary S; Kanoute, Moussa B; Cisse, Kadidia B; Dembele, Adama B; Keita, Sekouba; Gamain, Benoît; Gaoussou, Santara; Issiaka, Djibrilla; Dicko, Alassane; Duffy, Patrick E; Fried, Michal

    2017-10-24

    P. falciparum virulence is related to adhesion and sequestration of infected erythrocytes (IE) in deep vascular beds, but the endothelial receptors involved in severe malaria remain unclear. In the largest ever study of clinical isolates, we surveyed adhesion of freshly collected IE from children under 5 years of age in Mali to identify novel vascular receptors, and examined the effects of host age, hemoglobin type, blood group and severe malaria on levels of IE adhesion to a panel of endothelial receptors. Several novel molecules, including integrin α3β1, VE-cadherin, ICAM-2, junctional adhesion molecule-B (JAM-B), laminin, and cellular fibronectin, supported binding of IE from children. Severe malaria was not significantly associated with levels of IE adhesion to any of the 19 receptors. Hemoglobin AC, which reduces severe malaria risk, reduced IE binding to the receptors CD36 and integrin α5β1, while hemoglobin AS did not modify IE adhesion to any receptors. Blood groups A, AB and B significantly reduced IE binding to ICAM-1. Severe malaria risk varies with age, but age significantly impacted the level of IE binding to only a few receptors: IE binding to JAM-B decreased with age, while binding to CD36 and integrin α5β1 significantly increased with age.

  15. Spatial variation and socio-economic determinants of Plasmodium falciparum infection in northeastern Tanzania

    DEFF Research Database (Denmark)

    Mmbando, Bruno P; Kamugisha, Mathias L; Lusingu, John P

    2011-01-01

    system (GPS) unit. The effects of risk factors were determined using generalized estimating equation and spatial risk of P. falciparum infection was modelled using a kernel (non-parametric) method. RESULTS: There was a significant spatial variation of P. falciparum infection, and urban areas were......ABSTRACT: BACKGROUND: Malaria due to Plasmodium falciparum is the leading cause of morbidity and mortality in Tanzania. According to health statistics, malaria accounts for about 30% and 15% of hospital admissions and deaths, respectively. The risk of P. falciparum infection varies across...... the country. This study describes the spatial variation and socio-economic determinants of P. falciparum infection in northeastern Tanzania. METHODS: The study was conducted in 14 villages located in highland, lowland and urban areas of Korogwe district. Four cross-sectional malaria surveys involving...

  16. Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

    Science.gov (United States)

    Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

    2014-01-01

    Background In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species). More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. Objectives To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. Search methods We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Selection criteria Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. Data collection and analysis For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and

  17. Parasite density and the spectrum of clinical illness in falciparum malaria

    International Nuclear Information System (INIS)

    Ali, H.; Mahmood, T.; Ahmed, N.

    2008-01-01

    To determine the impact of percentage parasitemia and clinical features on morbidity and mortality in patients with P. falciparum malaria. Seventy-six adult patients of smear positive P. falciparum malaria were selected for the study. Parasite density was estimated on thin blood film and expressed as percentage of red blood cells parasitized. Patients were divided into three groups on the basis of parasite density. The data was analyzed on SPSS version 12. Results were expressed as percentages, mean and standard deviations. P-value 10%. Comparative analysis of the groups showed that pallor, impaired consciousness, jaundice or malarial hepatitis, thrombocytopenia, acute renal failure, DIC, and mortality were all strongly associated with the density of Plasmodium falciparum malaria (p=0.001). Parasite density was not related to age, gender and hepatosplenomegaly. High parasite density was associated with severe clinical illness, complications and mortality. Parasite counts of > 5% may be considered as hyperparasitaemia in this population of the world. (author)

  18. A Plasmodium falciparum strain expressing GFP throughout the parasite's life-cycle.

    Science.gov (United States)

    Talman, Arthur M; Blagborough, Andrew M; Sinden, Robert E

    2010-02-10

    The human malaria parasite Plasmodium falciparum is responsible for the majority of malaria-related deaths. Tools allowing the study of the basic biology of P. falciparum throughout the life cycle are critical to the development of new strategies to target the parasite within both human and mosquito hosts. We here present 3D7HT-GFP, a strain of P. falciparum constitutively expressing the Green Fluorescent Protein (GFP) throughout the life cycle, which has retained its capacity to complete sporogonic development. The GFP expressing cassette was inserted in the Pf47 locus. Using this transgenic strain, parasite tracking and population dynamics studies in mosquito stages and exo-erythrocytic schizogony is greatly facilitated. The development of 3D7HT-GFP will permit a deeper understanding of the biology of parasite-host vector interactions, and facilitate the development of high-throughput malaria transmission assays and thus aid development of new intervention strategies against both parasite and mosquito.

  19. The effect of sulphadoxine/pyrimethamine on gametocytes in falciparum malaria.

    Science.gov (United States)

    Ittiravivongs, A; Vasuvat, C; Kongrod, S

    1984-09-01

    A study of the effect of sulphadoxine/pyrimethamine (Fansidar) on P. falciparum's gametocytes in peripheral blood was carried out in Western Thailand. One group of 77 patients with asexual form P. falciparum sensitive to Fansidar were followed weekly to detect the appearance and the duration of gametocytes in peripheral blood after Fansidar treatment on the basis of thick blood film examination. Another group of 14 patients with sexual form P. falciparum was not given any antimalarial treatment and also followed up weekly. No significant difference of average duration of detectable gametocytes was observed between the groups. The average number of days that gametocytes appeared after asexual form in patients receiving treatment was the same as in the untreated group. It is unlikely that Fansidar has the stimulating effect on gametocytogenesis as previously reported.

  20. HUBUNGAN SENSISTIVITAS PLASMODIUM FALCIPARUM TERHADAP KOMBINASI PIRIMETAMIN/SULFADOKSIN DAN KLOROKUIN SECARA IN VITRO

    Directory of Open Access Journals (Sweden)

    Sahat Ompusunggu

    2012-09-01

    Full Text Available An in vitro sensitivity test was conducted to study the sensitivity of Plasmodium falciparum against chloroquine and pyrimethamine/sulphadoxine combination. The relationship between sensitivity of the parasite to the two drugs was also studied. A total of 72 patients from five localities were examined during 1984-1985. Test against chloroquine was conduc­ted according to WHO method, while against pyrimethamine/sulphadoxine combination, a modified method of Nguyen Dinh and Payne and Eastham and Rieckmann was used. The results showed that there is no relationship between the sensitivity of P. falciparum against pyrimethamine/ sulphadoxine combination and chloroquine. It can be concluded that in case of chloroquine resistant P. falciparum, pyrimethamine/sulphadoxine combination could be applied as an alternative chemotherapy.

  1. Limonene Arrests Parasite Development and Inhibits Isoprenylation of Proteins in Plasmodium falciparum

    Science.gov (United States)

    Moura, Ivan Cruz; Wunderlich, Gerhard; Uhrig, Maria L.; Couto, Alicia S.; Peres, Valnice J.; Katzin, Alejandro M.; Kimura, Emília A.

    2001-01-01

    Isoprenylation is an essential protein modification in eukaryotic cells. Herein, we report that in Plasmodium falciparum, a number of proteins were labeled upon incubation of intraerythrocytic forms with either [3H]farnesyl pyrophosphate or [3H]geranylgeranyl pyrophosphate. By thin-layer chromatography, we showed that attached isoprenoids are partially modified to dolichol and other, uncharacterized, residues, confirming active isoprenoid metabolism in this parasite. Incubation of blood-stage P. falciparum treated with the isoprenylation inhibitor limonene significantly decreased the parasites' progression from the ring stage to the trophozoite stage and at 1.22 mM, 50% of the parasites died after the first cycle. Using Ras- and Rap-specific monoclonal antibodies, putative Rap and Ras proteins of P. falciparum were immunoprecipitated. Upon treatment with 0.5 mM limonene, isoprenylation of these proteins was significantly decreased, possibly explaining the observed arrest of parasite development. PMID:11502528

  2. Genetic characterization of an epidemic of Plasmodium falciparum malaria among Yanomami Amerindians.

    Science.gov (United States)

    Laserson, K F; Petralanda, I; Almera, R; Barker, R H; Spielman, A; Maguire, J H; Wirth, D F

    1999-12-01

    Malaria parasites are genetically diverse at all levels of endemicity. In contrast, the merozoite surface protein (MSP) alleles in samples from 2 isolated populations of Yanomami Amerindians during an epidemic of Plasmodium falciparum were identical. The nonvariable restriction fragment length polymorphism patterns further suggested that the sequential outbreak comprised only a single P. falciparum genotype. By examination of serial samples from single human infections, the MSP characteristics were found to remain constant throughout the course of infection. An apparent clonal population structure of parasites seemed to cause outbreaks in small isolated villages. The use of standard molecular epidemiologic methods to measure genetic diversity in malaria revealed the occurrence of a genetically monomorphic population of P. falciparum within a human community.

  3. Phenotypic and genotypic characterization of Thai isolates of Plasmodium falciparum after an artemisinin resistance containment project.

    Science.gov (United States)

    Thita, Thunyapit; Jadsri, Pimrat; Thamkhantho, Jarupatr; Ruang-Areerate, Toon; Suwandittakul, Nantana; Sitthichot, Naruemon; Mahotorn, Kittiya; Tan-Ariya, Peerapan; Mungthin, Mathirut

    2018-05-15

    In Thailand, artemisinin-based combination therapy (ACT) has been used to treat uncomplicated falciparum malaria since 1995. Unfortunately, artemisinin resistance has been reported from Thailand and other Southeast Asian countries since 2003. Malarone ® , a combination of atovaquone-proguanil (ATQ-PG), has been used to cease artemisinin pressure in some areas along Thai-Cambodia border, as part of an artemisinin resistance containment project since 2009. This study aimed to determine genotypes and phenotypes of Plasmodium falciparum isolates collected from the Thai-Cambodia border after the artemisinin resistance containment project compared with those collected before. One hundred and nine of P. falciparum isolates collected from Thai-Cambodia border from Chanthaburi and Trat provinces during 1988-2016 were used in this study. Of these, 58 isolates were collected after the containment. These parasite isolates were characterized for in vitro antimalarial sensitivities including chloroquine (CQ), quinine (QN), mefloquine (MQ), piperaquine (PPQ), artesunate (AS), dihydroartemisinin (DHA), ATQ and PG and genetic markers for drug resistance including the Kelch13 (k13), Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1) and cytochrome b (cytb) genes. Mean CQ, QN, MQ, PPQ and AS IC 50 s of the parasite isolates collected from 2009 to 2016 exhibited significantly higher than those of parasites collected before 2009. Approximately 57% exhibited in vitro MQ resistance. Approximately 94% of the isolates collected from 2009 to 2016 contained the pfmdr1 184F allele. Mutations of the k13 gene were detected in approximately 90% of the parasites collected from 2009 to 2016 which were significantly higher than the parasite isolates collected before. No ATQ-resistant genotype and phenotype of P. falciparum were found among the isolates collected after the containment project. Although the containment project had been

  4. Cellular effects of curcumin on Plasmodium falciparum include disruption of microtubules.

    Directory of Open Access Journals (Sweden)

    Rimi Chakrabarti

    Full Text Available Curcumin has been widely investigated for its myriad cellular effects resulting in reduced proliferation of various eukaryotic cells including cancer cells and the human malaria parasite Plasmodium falciparum. Studies with human cancer cell lines HT-29, Caco-2, and MCF-7 suggest that curcumin can bind to tubulin and induce alterations in microtubule structure. Based on this finding, we investigated whether curcumin has any effect on P. falciparum microtubules, considering that mammalian and parasite tubulin are 83% identical. IC50 of curcumin was found to be 5 µM as compared to 20 µM reported before. Immunofluorescence images of parasites treated with 5 or 20 µM curcumin showed a concentration-dependent effect on parasite microtubules resulting in diffuse staining contrasting with the discrete hemispindles and subpellicular microtubules observed in untreated parasites. The effect on P. falciparum microtubules was evident only in the second cycle for both concentrations tested. This diffuse pattern of tubulin fluorescence in curcumin treated parasites was similar to the effect of a microtubule destabilizing drug vinblastine on P. falciparum. Molecular docking predicted the binding site of curcumin at the interface of alpha and beta tubulin, similar to another destabilizing drug colchicine. Data from predicted drug binding is supported by results from drug combination assays showing antagonistic interactions between curcumin and colchicine, sharing a similar binding site, and additive/synergistic interactions of curcumin with paclitaxel and vinblastine, having different binding sites. This evidence suggests that cellular effects of curcumin are at least, in part, due to its perturbing effect on P. falciparum microtubules. The action of curcumin, both direct and indirect, on P. falciparum microtubules is discussed.

  5. Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand.

    Science.gov (United States)

    Pattaradilokrat, Sittiporn; Sawaswong, Vorthon; Simpalipan, Phumin; Kaewthamasorn, Morakot; Siripoon, Napaporn; Harnyuttanakorn, Pongchai

    2016-10-21

    An effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3) gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown. The msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani) in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (F st ) and neutrality tests (Tajima's D, Fu and Li D* and Fu and Li' F* tests) to determine any signature of selection. The sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia. This study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

  6. Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum.

    Science.gov (United States)

    Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

    2013-06-07

    Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions.

  7. Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum*

    Science.gov (United States)

    Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

    2013-01-01

    Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions. PMID:23615908

  8. Primaquine or other 8-aminoquinolines for reducing Plasmodium falciparum transmission

    Science.gov (United States)

    Graves, Patricia M; Choi, Leslie; Gelband, Hellen; Garner, Paul

    2018-01-01

    Background The 8-aminoquinoline (8AQ) drugs act on Plasmodium falciparum gametocytes, which transmit malaria from infected people to mosquitoes. In 2012, the World Health Organization (WHO) recommended a single dose of 0.25 mg/kg primaquine (PQ) be added to malaria treatment schedules in low-transmission areas or those with artemisinin resistance. This replaced the previous recommendation of 0.75 mg/kg, aiming to reduce haemolysis risk in people with glucose-6-phosphate dehydrogenase deficiency, common in people living in malarious areas. Whether this approach, and at this dose, is effective in reducing transmission is not clear. Objectives To assess the effects of single dose or short-course PQ (or an alternative 8AQ) alongside treatment for people with P. falciparum malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; and the WHO International Clinical Trials Registry Platform (ICRTP) portal using ‘malaria*', ‘falciparum', ‘primaquine', ‘8-aminoquinoline', and eight 8AQ drug names as search terms. We checked reference lists of included trials, and contacted researchers and organizations. Date of last search: 21 July 2017. Selection criteria Randomized controlled trials (RCTs) or quasi-RCTs in children or adults, adding PQ (or alternative 8AQ) as a single dose or short course alongside treatment for P. falciparum malaria. Data collection and analysis Two authors screened abstracts, applied inclusion criteria, and extracted data. We sought evidence on transmission (community incidence), infectiousness (people infectious and mosquitoes infected), and potential infectiousness (gametocyte measures assessed by microscopy or polymerase chain reaction [PCR]). We grouped trials into artemisinin and non-artemisinin treatments, and stratified by PQ dose (low, 0.2 to 0.25 mg/kg; moderate, 0.4 to 0.5 mg/kg; high, 0.75 mg/kg). We

  9. A versatile, high through-put, bead-based phagocytosis assay for Plasmodium falciparum

    DEFF Research Database (Denmark)

    Lloyd, Yukie M.; Ngati, Elise P.; Salanti, Ali

    2017-01-01

    Antibody-mediated phagocytosis is an important immune effector mechanism against Plasmodium falciparum-infected erythrocytes (IE); however, current phagocytosis assays use IE collected from infected individuals or from in vitro cultures of P. falciparum, making them prone to high variation....... A simple, high-throughput flow cytometric assay was developed that uses THP-1 cells and fluorescent beads covalently-coupled with the malarial antigen VAR2CSA. The assay is highly repeatable, provides both the overall percent phagocytosis and semi-quantitates the number of antigen-coupled beads...

  10. A Lectin-Like Receptor is Involved in Invasion of Erythrocytes by Plasmodium falciparum

    Science.gov (United States)

    Jungery, M.; Pasvol, G.; Newbold, C. I.; Weatherall, D. J.

    1983-02-01

    Glycophorin both in solution and inserted into liposomes blocks invasion of erythrocytes by the malaria parasite Plasmodium falciparum. Furthermore, one sugar, N-acetyl-D-glucosamine (GlcNAc), completely blocks invasion of the erythrocyte by this parasite. GlcNAc coupled to bovine serum albumin to prevent the sugar entering infected erythrocytes was at least 100,000 times more effective than GlcNAc alone. Bovine serum albumin coupled to lactose or bovine serum albumin alone had no effect on invasion. These results suggest that the binding of P. falciparum to erythrocytes is lectin-like and is determined by carbohydrates on glycophorin.

  11. Molecular cloning of a K+ channel from the malaria parasite Plasmodium falciparum

    DEFF Research Database (Denmark)

    Ellekvist, Peter; Ricke, Christina Høier; Litman, Thomas

    2004-01-01

    In most living cells, K(+) channels are important for the generation of the membrane potential and for volume regulation. The parasite Plasmodium falciparum, which causes malignant malaria, must be able to deal with large variations in the ambient K(+) concentration: it is exposed to high...... concentrations of K(+) when inside the erythrocyte and low concentrations when in plasma. In the recently published genome of P. falciparum, we have identified a gene, pfkch1, encoding a potential K(+) channel, which to some extent resembles the big-conductance (BK) K(+) channel. We have cloned the approximately...

  12. Regulation of antigenic variation in Plasmodium falciparum: censoring freedom of expression?

    Science.gov (United States)

    Duffy, Michael F; Reeder, John C; Brown, Graham V

    2003-03-01

    Plasmodium falciparum employs a strategy of clonal antigenic variation to evade the host immune response during the intraerythrocytic stage of its life cycle. The major variant parasite molecule is the P. falciparum erythrocyte membrane protein (PfEMP)1, which is encoded by the var multigene family. The parasite switches between different PfEMP1 molecules through regulation of var transcription. Recent studies have shed considerable light on this process, but much remains unknown. However, striking parallels between transcriptional control of var and genes in other organisms provide direction for future studies.

  13. Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens

    DEFF Research Database (Denmark)

    Nielsen, Morten A; Vestergaard, Lasse S; Lusingu, John

    2004-01-01

    The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity......, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries...

  14. Chronic Plasmodium falciparum infections in an area of low intensity malaria transmission in the Sudan

    DEFF Research Database (Denmark)

    Hamad, A A; El Hassan, I M; El Khalifa, A A

    2000-01-01

    Chronic Plasmodium falciparum malaria infections in a Sudanese village, in an area of seasonal and unstable malaria transmission, were monitored and genetically characterized to study the influence of persistent infection on the immunology and epidemiology of low endemicity malaria. During...... the October-December malaria season of 1996, 51 individuals out of a population of 420 had confirmed and treated P. falciparum malaria in the village of Daraweesh in eastern Sudan. In a cross-sectional survey carried out in December 1996, an additional 6 individuals were found to harbour a microscopically...

  15. P. falciparum infection and maternofetal antibody transfer in malaria-endemic settings of varying transmission.

    Directory of Open Access Journals (Sweden)

    Alistair R D McLean

    Full Text Available During pregnancy, immunoglobulin G (IgG is transferred from the mother to the fetus, providing protection from disease in early infancy. Plasmodium falciparum infections may reduce maternofetal antibody transfer efficiency, but mechanisms remain unclear.Mother-cord paired serum samples collected at delivery from Papua New Guinea (PNG and the Thailand-Myanmar Border Area (TMBA were tested for IgG1 and IgG3 to four P. falciparum antigens and measles antigen, as well as total serum IgG. Multivariable linear regression was conducted to assess the association of peripheral P. falciparum infection during pregnancy or placental P. falciparum infection assessed at delivery with maternofetal antibody transfer efficiency. Path analysis assessed the extent to which associations between P. falciparum infection and antibody transfer were mediated by gestational age at delivery or levels of maternal total serum IgG.Maternofetal antibody transfer efficiency of IgG1 and IgG3 was lower in PNG compared to TMBA (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.88 to 0.09, median of -0.20 log2 units. Placental P. falciparum infections were associated with substantially lower maternofetal antibody transfer efficiency in PNG primigravid women (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.62 to -0.10, median of -0.36 log2 units, but not multigravid women. The lower antibody transfer efficiency amongst primigravid women with placental infection was only partially mediated by gestational age at delivery (proportion indirect effect ranged from 0% to 18%, whereas no mediation effects of maternal total serum IgG were observed.Primigravid women may be at risk of impaired maternofetal antibody transport with placental P. falciparum infection. Direct effects of P. falciparum on the placenta, rather than earlier gestational age and elevated serum IgG, are likely responsible for

  16. Characterizing the impact of sustained sulfadoxine/pyrimethamine use upon the Plasmodium falciparum population in Malawi

    DEFF Research Database (Denmark)

    Ravenhall, Matt; Benavente, Ernest Diez; Mipando, Mwapatsa

    2016-01-01

    BACKGROUND: Malawi experienced prolonged use of sulfadoxine/pyrimethamine (SP) as the front-line anti-malarial drug, with early replacement of chloroquine and delayed introduction of artemisinin-based combination therapy. Extended use of SP, and its continued application in pregnancy is impacting...... the genomic variation of the Plasmodium falciparum population. METHODS: Whole genome sequence data of P. falciparum isolates covering 2 years of transmission within Malawi, alongside global datasets, were used. More than 745,000 SNPs were identified, and differences in allele frequencies between countries...

  17. Novel short chain chloroquine analogues retain activity against chloroquine resistant K1 Plasmodium falciparum.

    Science.gov (United States)

    Stocks, Paul A; Raynes, Kaylene J; Bray, Patrick G; Park, B Kevin; O'Neill, Paul M; Ward, Stephen A

    2002-11-07

    A series of short chain chloroquine (CQ) derivatives have been synthesized in one step from readily available starting materials. The diethylamine function of CQ is replaced by shorter alkylamine groups (4-9) containing secondary or tertiary terminal nitrogens. Some of these derivatives are significantly more potent than CQ against a CQ resistant strain of Plasmodium falciparum in vitro. We conclude that the ability to accumulate at higher concentrations within the food vacuole of the parasite is an important parameter that dictates their potency against CQ sensitive and the chloroquine resistant K1 P. falciparum.

  18. Molecular epidemiology of drug-resistant Plasmodium falciparum in Benguela province, Angola.

    Science.gov (United States)

    Foumane Ngane, Vincent; Allico Djaman, Joseph; Culeux, Cécile; Piette, Nathalie; Carnevale, Pierre; Besnard, Patrick; Fortes, Filomeno; Basco, Leonardo K; Tahar, Rachida

    2015-03-14

    The malaria situation has been worsening in Angola, partly due to armed conflict until the recent past and drug-resistant Plasmodium falciparum. Malaria transmission is heterogeneous within the country, and data on drug-resistant malaria in different parts of the country are incomplete. The aim of the present study was to evaluate resistance to 4-aminoquinolines and antifolate drugs in P. falciparum isolates collected in Benguela province, central Angola, using molecular markers. Fingerprick capillary blood was collected from asymptomatic children aged less than 15 years old during a household survey in and around Balombo town in 2010-2011. Samples were screened for P. falciparum by nested PCR. Molecular markers (P. falciparum dihydrofolate reductase [pfdhfr], P. falciparum dihydropteroate synthase [pfdhps], P. falciparum chloroquine resistance transporter [pfcrt], and P. falciparum multidrug-resistance gene 1 [pfmdr1]) were sequenced to determine the key codons associated with drug resistance. A total of 60 blood samples were positive for P. falciparum. Most isolates with successful PCR amplification had mutant pfdhfr alleles, with either double mutant AICNI (69%) or triple mutant AIRNI (21%) haplotypes. A16V, S108T, and I164L substitutions were not found. Many of the isolates were carriers of either SGKAA (60%) or AGKAA (27%) pfdhps haplotype. K540E substitution was absent. There were only two pfcrt haplotypes: wild-type CVMNK (11%) and mutant CVIET (89%). Wild-type pfmdr1 NYSND haplotype was found in 19% of the isolates, whereas single mutant pfmdr1 YYSND and NFSND haplotypes occurred in 48% and 11%, respectively. Double mutant pfmdr1 haplotypes (YFSND and YYSNY) occurred rarely. The results suggest that the high prevalence of mutant pfcrt CVIET haplotype is in agreement with low clinical efficacy of chloroquine observed in earlier studies and that the double pfdhfr mutant AICNI and single pfdhps mutant SGKAA are currently the predominant haplotypes associated

  19. Comparative population structure of Plasmodium malariae and Plasmodium falciparum under different transmission settings in Malawi

    Directory of Open Access Journals (Sweden)

    Molyneux Malcolm E

    2011-02-01

    Full Text Available Abstract Background Described here is the first population genetic study of Plasmodium malariae, the causative agent of quartan malaria. Although not as deadly as Plasmodium falciparum, P. malariae is more common than previously thought, and is frequently in sympatry and co-infection with P. falciparum, making its study increasingly important. This study compares the population parameters of the two species in two districts of Malawi with different malaria transmission patterns - one seasonal, one perennial - to explore the effects of transmission on population structures. Methods Six species-specific microsatellite markers were used to analyse 257 P. malariae samples and 257 P. falciparum samples matched for age, gender and village of residence. Allele sizes were scored to within 2 bp for each locus and haplotypes were constructed from dominant alleles in multiple infections. Analysis of multiplicity of infection (MOI, population differentiation, clustering of haplotypes and linkage disequilibrium was performed for both species. Regression analyses were used to determine association of MOI measurements with clinical malaria parameters. Results Multiple-genotype infections within each species were common in both districts, accounting for 86.0% of P. falciparum and 73.2% of P. malariae infections and did not differ significantly with transmission setting. Mean MOI of P. falciparum was increased under perennial transmission compared with seasonal (3.14 vs 2.59, p = 0.008 and was greater in children compared with adults. In contrast, P. malariae mean MOI was similar between transmission settings (2.12 vs 2.11 and there was no difference between children and adults. Population differentiation showed no significant differences between villages or districts for either species. There was no evidence of geographical clustering of haplotypes. Linkage disequilibrium amongst loci was found only for P. falciparum samples from the seasonal transmission

  20. Serine Proteolytic Pathway Activation Reveals an Expanded Ensemble of Wound Response Genes in Drosophila

    Science.gov (United States)

    Patterson, Rachel A.; Juarez, Michelle T.; Hermann, Anita; Sasik, Roman; Hardiman, Gary; McGinnis, William

    2013-01-01

    After injury to the animal epidermis, a variety of genes are transcriptionally activated in nearby cells to regenerate the missing cells and facilitate barrier repair. The range and types of diffusible wound signals that are produced by damaged epidermis and function to activate repair genes during epidermal regeneration remains a subject of very active study in many animals. In Drosophila embryos, we have discovered that serine protease function is locally activated around wound sites, and is also required for localized activation of epidermal repair genes. The serine protease trypsin is sufficient to induce a striking global epidermal wound response without inflicting cell death or compromising the integrity of the epithelial barrier. We developed a trypsin wounding treatment as an amplification tool to more fully understand the changes in the Drosophila transcriptome that occur after epidermal injury. By comparing our array results with similar results on mammalian skin wounding we can see which evolutionarily conserved pathways are activated after epidermal wounding in very diverse animals. Our innovative serine protease-mediated wounding protocol allowed us to identify 8 additional genes that are activated in epidermal cells in the immediate vicinity of puncture wounds, and the functions of many of these genes suggest novel genetic pathways that may control epidermal wound repair. Additionally, our data augments the evidence that clean puncture wounding can mount a powerful innate immune transcriptional response, with different innate immune genes being activated in an interesting variety of ways. These include puncture-induced activation only in epidermal cells in the immediate vicinity of wounds, or in all epidermal cells, or specifically in the fat body, or in multiple tissues. PMID:23637905

  1. Human mast cell tryptase: Multiple cDNAs and genes reveal a multigene serine protease family

    International Nuclear Information System (INIS)

    Vanderslice, P.; Ballinger, S.M.; Tam, E.K.; Goldstein, S.M.; Craik, C.S.; Caughey, G.H.

    1990-01-01

    Three different cDNAs and a gene encoding human skin mast cell tryptase have been cloned and sequenced in their entirety. The deduced amino acid sequences reveal a 30-amino acid prepropeptide followed by a 245-amino acid catalytic domain. The C-terminal undecapeptide of the human preprosequence is identical in dog tryptase and appears to be part of a prosequence unique among serine proteases. The differences among the three human tryptase catalytic domains include the loss of a consensus N-glycosylation site in one cDNA, which may explain some of the heterogeneity in size and susceptibility to deglycosylation seen in tryptase preparations. All three tryptase cDNAs are distinct from a recently reported cDNA obtained from a human lung mast cell library. A skin tryptase cDNA was used to isolate a human tryptase gene, the exons of which match one of the skin-derived cDNAs. The organization of the ∼1.8-kilobase-pair tryptase gene is unique and is not closely related to that of any other mast cell or leukocyte serine protease. The 5' regulatory regions of the gene share features with those of other serine proteases, including mast cell chymase, but are unusual in being separated from the protein-coding sequence by an intron. High-stringency hybridization of a human genomic DNA blot with a fragment of the tryptase gene confirms the presence of multiple tryptase genes. These findings provide genetic evidence that human mast cell tryptases are the products of a multigene family

  2. IDENTIFICATION OF SERINE CARBAPENEMASE AND METALLOCARBAPENEMASE ENZYMES IN PSEUDOMONAS AERUGINOSA IN GEMS MEDICAL COLLEGE, RAGOLU, SRIKAKULAM

    Directory of Open Access Journals (Sweden)

    Radhika

    2016-06-01

    Full Text Available Various carbapenems have been reported in Pseudomonas aeruginosa such as VIM, NDM & OXA-48, etc. In addition, carbapenemase producers are usually associated with many other non–β-lactam resistance determinants which give rise to multidrug and pan drug resistant isolates. Detection of these enzymes in infected patients and in carriers are the two main approaches for prevention of their spread. Potential carbapenemase producers are currently screened first by susceptibility testing, using breakpoint values for carbapenems. However, many carbapenemase producers do not confer obvious resistance levels to carbapenems. So there is need for Laboratories to search for carbapenemase producers. In such instance, phenotypic based test such as Modified Hodge Test (MHT is very much useful in confirming in vitro production of carbapenemase enzymes. But this test does not differentiate serine carbapenemase enzyme (i.e. Ambler class A & C from metallocarbapenemase (i.e. Ambler class B. To differentiate these two enzymes, MHT positive isolates can be subjected to Disc Synergy test. These two tests are highly sensitive and specific and adaptable to any laboratory in the world. Out of 100 ceftazidime resistant Pseudomonas aeruginosa, 75(75% were sensitive, 7(7% were intermediate sensitive and 18(18% were resistant to imipenem. When the 18 imipenem resistant strains were subjected to Modified Hodge test, 15 gave positive results. When the 15 MHT positive strains subjected to disc synergy test, 8 were positive and 7 were negative showing that 8 were producing metallocarbapenemases and 7 were producing serine carbapenemases. Out of 7 intermediately imipenem sensitive isolates, 2 were producing metallocarbapenemase and 3 were producing serine carbapenemase. Hence, total number of imipenem resistant Pseudomonas aeruginosa isolates were 23.

  3. Phorbol ester-induced serine phosphorylation of the insulin receptor decreases its tyrosine kinase activity.

    Science.gov (United States)

    Takayama, S; White, M F; Kahn, C R

    1988-03-05

    The effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the function of the insulin receptor was examined in intact hepatoma cells (Fao) and in solubilized extracts purified by wheat germ agglutinin chromatography. Incubation of ortho[32P]phosphate-labeled Fao cells with TPA increased the phosphorylation of the insulin receptor 2-fold after 30 min. Analysis of tryptic phosphopeptides from the beta-subunit of the receptor by reverse-phase high performance liquid chromatography and determination of their phosphoamino acid composition suggested that TPA predominantly stimulated phosphorylation of serine residues in a single tryptic peptide. Incubation of the Fao cells with insulin (100 nM) for 1 min stimulated 4-fold the phosphorylation of the beta-subunit of the insulin receptor. Prior treatment of the cells with TPA inhibited the insulin-stimulated tyrosine phosphorylation by 50%. The receptors extracted with Triton X-100 from TPA-treated Fao cells and purified on immobilized wheat germ agglutinin retained the alteration in kinase activity and exhibited a 50% decrease in insulin-stimulated tyrosine autophosphorylation and phosphotransferase activity toward exogenous substrates. This was due primarily to a decrease in the Vmax for these reactions. TPA treatment also decreased the Km of the insulin receptor for ATP. Incubation of the insulin receptor purified from TPA-treated cells with alkaline phosphatase decreased the phosphate content of the beta-subunit to the control level and reversed the inhibition, suggesting that the serine phosphorylation of the beta-subunit was responsible for the decreased tyrosine kinase activity. Our results support the notion that the insulin receptor is a substrate for protein kinase C in the Fao cell and that the increase in serine phosphorylation of the beta-subunit of the receptor produced by TPA treatment inhibited tyrosine kinase activity in vivo and in vitro. These data suggest that protein kinase C may regulate the function

  4. Efficient Reassignment of a Frequent Serine Codon in Wild-Type Escherichia coli.

    Science.gov (United States)

    Ho, Joanne M; Reynolds, Noah M; Rivera, Keith; Connolly, Morgan; Guo, Li-Tao; Ling, Jiqiang; Pappin, Darryl J; Church, George M; Söll, Dieter

    2016-02-19

    Expansion of the genetic code through engineering the translation machinery has greatly increased the chemical repertoire of the proteome. This has been accomplished mainly by read-through of UAG or UGA stop codons by the noncanonical aminoacyl-tRNA of choice. While stop codon read-through involves competition with the translation release factors, sense codon reassignment entails competition with a large pool of endogenous tRNAs. We used an engineered pyrrolysyl-tRNA synthetase to incorporate 3-iodo-l-phenylalanine (3-I-Phe) at a number of different serine and leucine codons in wild-type Escherichia coli. Quantitative LC-MS/MS measurements of amino acid incorporation yields carried out in a selected reaction monitoring experiment revealed that the 3-I-Phe abundance at the Ser208AGU codon in superfolder GFP was 65 ± 17%. This method also allowed quantification of other amino acids (serine, 33 ± 17%; phenylalanine, 1 ± 1%; threonine, 1 ± 1%) that compete with 3-I-Phe at both the aminoacylation and decoding steps of translation for incorporation at the same codon position. Reassignments of different serine (AGU, AGC, UCG) and leucine (CUG) codons with the matching tRNA(Pyl) anticodon variants were met with varying success, and our findings provide a guideline for the choice of sense codons to be reassigned. Our results indicate that the 3-iodo-l-phenylalanyl-tRNA synthetase (IFRS)/tRNA(Pyl) pair can efficiently outcompete the cellular machinery to reassign select sense codons in wild-type E. coli.

  5. A Mycobacterium avium subsp. paratuberculosis predicted serine protease is associated with acid stress and intraphagosomal survival

    Directory of Open Access Journals (Sweden)

    Abirami Kugadas

    2016-08-01

    Full Text Available AbstractThe ability to maintain intra-cellular pH is crucial for bacteria and other microbes to survive in diverse environments, particularly those that undergo fluctuations in pH. Mechanisms of acid resistance remain poorly understood in mycobacteria. Although studies investigating acid stress in M. tuberculosis are gaining traction, few center on Mycobacterium avium subsp. paratuberculosis (MAP, the etiological agent of chronic enteritis in ruminants. We identified a MAP acid stress response network involved in macrophage infection. The central node of this network was MAP0403, a predicted serine protease that shared an 86% amino acid identity with MarP in M. tuberculosis. Previous studies confirmed MarP as a serine protease integral to maintaining intra-bacterial pH and survival in acid in vitro and in vivo. We show that MAP0403 is upregulated in infected macrophage and MAC-T cells and coincided with phagosome acidification. Treatment of mammalian cells with bafilomcyin A1, a potent inhibitor of phagosomal vATPases, diminished MAP0403 transcription. MAP0403 expression was also noted in acidic medium. A surrogate host, M. smegmatis mc2 155, was designed to express MAP0403 and when exposed to either macrophages or in vitro acid stress had increase bacterial cell viability, which corresponds to maintenance of intra-bacterial pH in acidic (pH = 5 conditions. These data suggest that MAP0403 may be the equivalent of MarP in MAP. Future studies confirming MAP0403 as a serine protease and exploring its structure and possible substrates are warranted.

  6. Standardizing estimates of the Plasmodium falciparum parasite rate

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    Smith David L

    2007-09-01

    Full Text Available Abstract Background The Plasmodium falciparum parasite rate (PfPR is a commonly reported index of malaria transmission intensity. PfPR rises after birth to a plateau before declining in older children and adults. Studies of populations with different age ranges generally report average PfPR, so age is an important source of heterogeneity in reported PfPR data. This confounds simple comparisons of PfPR surveys conducted at different times or places. Methods Several algorithms for standardizing PfPR were developed using 21 studies that stratify in detail PfPR by age. An additional 121 studies were found that recorded PfPR from the same population over at least two different age ranges; these paired estimates were used to evaluate these algorithms. The best algorithm was judged to be the one that described most of the variance when converting the PfPR pairs from one age-range to another. Results The analysis suggests that the relationship between PfPR and age is predictable across the observed range of malaria endemicity. PfPR reaches a peak after about two years and remains fairly constant in older children until age ten before declining throughout adolescence and adulthood. The PfPR pairs were poorly correlated; using one to predict the other would explain only 5% of the total variance. By contrast, the PfPR predicted by the best algorithm explained 72% of the variance. Conclusion The PfPR in older children is useful for standardization because it has good biological, epidemiological and statistical properties. It is also historically consistent with the classical categories of hypoendemic, mesoendemic and hyperendemic malaria. This algorithm provides a reliable method for standardizing PfPR for the purposes of comparing studies and mapping malaria endemicity. The scripts for doing so are freely available to all.

  7. Defining childhood severe falciparum malaria for intervention studies.

    Directory of Open Access Journals (Sweden)

    Philip Bejon

    2007-08-01

    Full Text Available Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no "gold standard" individual test for severe malaria, malaria-attributable fractions (MAFs can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints.A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor, lower respiratory tract infection (clinician's final diagnosis, meningitis (on cerebrospinal fluid [CSF] examination, and bacteraemia were associated with reduced MAFs. The overall MAF was 85% (95% confidence interval [CI] 83.8%-86.1% without excluding these conditions, 89% (95% CI 88.4%-90.2% after exclusions, and 95% (95% CI 94.0%-95.5% when a threshold of 2,500 parasites/mul was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%-83%.The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis, bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition.

  8. Inhibition of Human Serine Racemase, an Emerging Target for Medicinal Chemistry

    Czech Academy of Sciences Publication Activity Database

    Jirásková-Vaníčková, Jana; Ettrich, Rüdiger; Vorlová, Barbora; Hoffman, Hillary Elizabeth; Lepšík, Martin; Jansa, Petr; Konvalinka, Jan

    2011-01-01

    Roč. 12, č. 7 (2011), s. 1037-1055 ISSN 1389-4501 R&D Projects: GA MŠk 1M0508; GA ČR GA203/08/0114 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z60870520 Keywords : amino acid analogs * L-erythro-3-hydroxyaspartate (L-EHA) * D-serine * neurodegenerative diseases * NMDA receptors * pyridoxal-5´-phosphate (PLP) Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.553, year: 2011

  9. Trypsin- and Chymotrypsin-Like Serine Proteases in Schistosoma mansoni - 'The Undiscovered Country'

    Czech Academy of Sciences Publication Activity Database

    Horn, Martin; Fajtová, Pavla; Arreola, L. R.; Ulrychová, Lenka; Bartošová-Sojková, Pavla; Franta, Zdeněk; Protasio, A. V.; Opavský, David; Vondrášek, Jiří; McKerrow, J. H.; Mareš, Michael; Caffrey, C. R.; Dvořák, Jan

    2014-01-01

    Roč. 8, č. 3 (2014), e2766/1-e2766/13 ISSN 1935-2735 R&D Projects: GA ČR(CZ) GAP302/11/1481; GA MŠk(CZ) ME10011 EU Projects: European Commission(XE) 248642 - SCHISTOSOMA PROTEASE Institutional support: RVO:61388963 ; RVO:68378050 ; RVO:60077344 Keywords : schistosomiasis * blood fluke * serine protease Subject RIV: CE - Biochemistry; EB - Genetics ; Molecular Biology (UMG-J); FN - Epidemiology, Contagious Diseases ; Clinical Immunology (BC-A) Impact factor: 4.446, year: 2014 http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0002766

  10. An analysis of 3D solvation structure in biomolecules: application to coiled coil serine and bacteriorhodopsin.

    Science.gov (United States)

    Hirano, Kenji; Yokogawa, Daisuke; Sato, Hirofumi; Sakaki, Shigeyoshi

    2010-06-17

    Three-dimensional (3D) solvation structure around coiled coil serine (Coil-Ser) and inner 3D hydration structure in bacteriorhodopsin (bR) were studied using a recently developed method named multicenter molecular Ornstein-Zernike equation (MC-MOZ) theory. In addition, a procedure for analyzing the 3D solvent distribution was proposed. The method enables us to calculate the coordination number of solvent water as well as the strength of hydrogen bonding between the water molecule and the protein. The results for Coil-Ser and bR showed very good agreement with the experimental observations.

  11. Malonate-based inhibitors of mammalian serine racemase: Kinetic characterization and structure-based computational study

    Czech Academy of Sciences Publication Activity Database

    Vorlová, Barbora; Nachtigallová, Dana; Jirásková-Vaníčková, Jana; Ajani, Haresh; Jansa, Petr; Řezáč, Jan; Fanfrlík, Jindřich; Otyepka, M.; Hobza, Pavel; Konvalinka, Jan; Lepšík, Martin

    2015-01-01

    Roč. 89, Jan 7 (2015), s. 189-197 ISSN 0223-5234 R&D Projects: GA ČR GBP208/12/G016 Grant - others:GA MŠk(CZ) ED2.1.00/03.0058 Program:ED Institutional support: RVO:61388963 Keywords : NMDA receptor * pyridoxal-5 '-phosphate-dependent enzyme * human/mouse serine racemase * malonate-based inhibitors * semiempirical quantum mechanical calculations Subject RIV: CE - Biochemistry Impact factor: 3.902, year: 2015

  12. Structural, Linear, and Nonlinear Optical and Mechanical Properties of New Organic L-Serine Crystal

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    K. Rajesh

    2014-01-01

    Full Text Available Nonlinear optical single crystal of organic amino acid L-Serine (LS was grown by slow evaporation technique. Solubility study of the compound was measured and metastable zone width was found. Single crystal X-ray diffraction study was carried out for the grown crystal. The linear and nonlinear optical properties of the crystal were confirmed by UV-Vis analysis and powder SHG tester. FT-IR spectrum was recorded and functional groups were analyzed. Vickers’ microhardness studies showed the mechanical strength of the grown crystal. Laser damage threshold value of the crystal was calculated. Photoconductivity studies reveal the conductivity of the crystal.

  13. Bacterial Serine/Threonine Protein Kinases in Host-Pathogen Interactions*

    Science.gov (United States)

    Canova, Marc J.; Molle, Virginie

    2014-01-01

    In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection. PMID:24554701

  14. Bacterial serine/threonine protein kinases in host-pathogen interactions.

    Science.gov (United States)

    Canova, Marc J; Molle, Virginie

    2014-04-04

    In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection.

  15. Artesunate plus pyronaridine for treating uncomplicated Plasmodium falciparum malaria.

    Science.gov (United States)

    Bukirwa, Hasifa; Unnikrishnan, B; Kramer, Christine V; Sinclair, David; Nair, Suma; Tharyan, Prathap

    2014-03-04

    The World Health Organization (WHO) recommends that people with uncomplicated Plasmodium falciparum malaria are treated using Artemisinin-based Combination Therapy (ACT). ACT combines three-days of a short-acting artemisinin derivative with a longer-acting antimalarial which has a different mode of action. Pyronaridine has been reported as an effective antimalarial over two decades of use in parts of Asia, and is currently being evaluated as a partner drug for artesunate. To evaluate the efficacy and safety of artesunate-pyronaridine compared to alternative ACTs for treating people with uncomplicated P. falciparum malaria. We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; ClinicalTrials.gov; the metaRegister of Controlled Trials (mRCT); and the WHO International Clinical Trials Search Portal up to 16 January 2014. We searched reference lists and conference abstracts, and contacted experts for information about ongoing and unpublished trials. Randomized controlled trials of artesunate-pyronaridine versus other ACTs in adults and children with uncomplicated P. falciparum malaria.For the safety analysis, we also included adverse events data from trials comparing any treatment regimen containing pyronaridine with regimens not containing pyronaridine. Two authors independently assessed trial eligibility and risk of bias, and extracted data. We combined dichotomous data using risk ratios (RR) and continuous data using mean differences (MD), and presented all results with a 95% confidence interval (CI). We used the GRADE approach to assess the quality of evidence. We included six randomized controlled trials enrolling 3718 children and adults. Artesunate-pyronaridine versus artemether-lumefantrineIn two multicentre trials, enrolling mainly older children and adults from west and south-central Africa, both artesunate-pyronaridine and

  16. Serine and alanine racemase activities of VanT: a protein necessary for vancomycin resistance in Enterococcus gallinarum BM4174.

    Science.gov (United States)

    Arias, C A; Weisner, J; Blackburn, J M; Reynolds, P E

    2000-07-01

    Vancomycin resistance in Enterococcus gallinarum results from the production of UDP-MurNAc-pentapeptide[D-Ser]. VanT, a membrane-bound serine racemase, is one of three proteins essential for this resistance. To investigate the selectivity of racemization of L-Ser or L-Ala by VanT, a strain of Escherichia coli TKL-10 that requires D-Ala for growth at 42 degrees C was used as host for transformation experiments using plasmids containing the full-length vanT from Ent. gallinarum or the alanine racemase gene (alr) of Bacillus stearothermophilus: both plasmids were able to complement E. coli TKL-10 at 42 degrees C. No alanine or serine racemase activities were detected in the host strain E. coli TKL-10 grown at 30, 34 or 37 degrees C. Serine and alanine racemase activities were found almost exclusively (96%) in the membrane fraction of E. coli TKL-10/pCA4(vanT): the alanine racemase activity of VanT was 14% of the serine racemase activity in both E. coli TKL-10/pCA4(vanT) and E. coli XL-1 Blue/pCA4(vanT). Alanine racemase activity was present mainly (95%) in the cytoplasmic fraction of E. coli TKL-10/pJW40(alr), with a trace (1.6%) of serine racemase activity. Additionally, DNA encoding the soluble domain of VanT was cloned and expressed in E. coli M15 as a His-tagged polypeptide and purified: this polypeptide also exhibited both serine and alanine racemase activities; the latter was approximately 18% of the serine racemase activity, similar to that of the full-length, membrane-bound enzyme. N-terminal sequencing of the purified His-tagged polypeptide revealed a single amino acid sequence, indicating that the formation of heterodimers between subunits of His-tagged C-VanT and endogenous alanine racemases from E. coli was unlikely. The authors conclude that the membrane-bound serine racemase VanT also has alanine racemase activity but is able to racemize serine more efficiently than alanine, and that the cytoplasmic domain is responsible for the racemase activity.

  17. Site-specific and synergistic stimulation of methylation on the bacterial chemotaxis receptor Tsr by serine and CheW

    Directory of Open Access Journals (Sweden)

    Weis Robert M

    2005-03-01

    Full Text Available Abstract Background Specific glutamates in the methyl-accepting chemotaxis proteins (MCPs of Escherichia coli are modified during sensory adaptation. Attractants that bind to MCPs are known to increase the rate of receptor modification, as with serine and the serine receptor (Tsr, which contributes to an increase in the steady-state (adapted methylation level. However, MCPs form ternary complexes with two cytoplasmic signaling proteins, the kinase (CheA and an adaptor protein (CheW, but their influences on receptor methylation are unknown. Here, the influence of CheW on the rate of Tsr methylation has been studied to identify contributions to the process of adaptation. Results Methyl group incorporation was measured in a series of membrane samples in which the Tsr molecules were engineered to have one available methyl-accepting glutamate residue (297, 304, 311 or 493. The relative rates at these sites (0.14, 0.05, 0.05 and 1, respectively differed from those found previously for the aspartate receptor (Tar, which was in part due to sequence differences between Tar and Tsr near site four. The addition of CheW generated unexpectedly large and site-specific rate increases, equal to or larger than the increases produced by serine. The increases produced by serine and CheW (added separately were the largest at site one, ~3 and 6-fold, respectively, and the least at site four, no change and ~2-fold, respectively. The rate increases were even larger when serine and CheW were added together, larger than the sums of the increases produced by serine and CheW added separately (except site four. This resulted in substantially larger serine-stimulated increases when CheW was present. Also, CheW enhanced methylation rates when either two or all four sites were available. Conclusion The increase in the rate of receptor methylation upon CheW binding contributes significantly to the ligand specificity and kinetics of sensory adaptation. The synergistic effect of

  18. Integration of ARTP mutagenesis with biosensor-mediated high-throughput screening to improve L-serine yield in Corynebacterium glutamicum.

    Science.gov (United States)

    Zhang, Xin; Zhang, Xiaomei; Xu, Guoqiang; Zhang, Xiaojuan; Shi, Jinsong; Xu, Zhenghong

    2018-05-03

    L-Serine is widely used in the pharmaceutical, food, and cosmetics industries. Although direct fermentative production of L-serine from sugar in Corynebacterium glutamicum has been achieved, the L-serine yield remains relatively low. In this study, atmospheric and room temperature plasma (ARTP) mutagenesis was used to improve the L-serine yield based on engineered C. glutamicum ΔSSAAI strain. Subsequently, we developed a novel high-throughput screening method using a biosensor constructed based on NCgl0581, a transcriptional factor specifically responsive to L-serine, so that L-serine concentration within single cell of C. glutamicum can be monitored via fluorescence-activated cell sorting (FACS). Novel L-serine-producing mutants were isolated from a large library of mutagenized cells. The mutant strain A36-pDser was screened from 1.2 × 10 5 cells, and the magnesium ion concentration in the medium was optimized specifically for this mutant. C. glutamicum A36-pDser accumulated 34.78 g/L L-serine with a yield of 0.35 g/g sucrose, which were 35.9 and 66.7% higher than those of the parent C. glutamicum ΔSSAAI-pDser strain, respectively. The L-serine yield achieved in this mutant was the highest of all reported L-serine-producing strains of C. glutamicum. Moreover, the whole-genome sequencing identified 11 non-synonymous mutations of genes associated with metabolic and transport pathways, which might be responsible for the higher L-serine production and better cell growth in C. glutamicum A36-pDser. This study explored an effective mutagenesis strategy and reported a novel high-throughput screening method for the development of L-serine-producing strains.

  19. Paludismo por Plasmodium falciparum adquirido en África subsahariana Plasmodium falciparum malaria acquired in Subsaharian Africa

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    Ricardo Durlach

    2009-02-01

    Full Text Available El objetivo de este trabajo es presentar los casos de paludismo por Plasmodium falciparum ocurridos en viajeros provenientes del África tropical, atendidos en el Hospital Alemán. Se definió paludismo de origen africano como la infección adquirida en un país del África subsahariana, diagnosticado y tratado en la Argentina. El diagnóstico se realizó por la clínica y la microscopía óptica en frotis de sangre periférica coloreados con Giemsa. Se revieron las historias clínicas de 11 pacientes adultos -cinco turistas y seis marineros mercantes- no oriundos de área endémica, sin condición inmunosupresora, ni morbilidad asociada, internados entre 1993 y 2007. El rango de edad fue de 21 a 48 años; nueve hombres y dos mujeres. Los pacientes fueron clasificados retrospectivamente en malaria grave (seis o no grave (cinco según cumplieran con uno o más de los criterios de gravedad de la Organización Mundial de la Salud. Todos presentaron fiebre como signo más significativo. Como complicaciones graves se observaron casos de insuficiencia renal, epistaxis, hemoglobinuria, hipoglucemia, edema pulmonar, acidosis y coma. Tres pacientes requirieron internación en la unidad de terapia intensiva. Todos sobrevivieron y solamente tres habían recibido la quimioprofilaxis correcta antes de viajar. El tratamiento se realizó con una o más de las siguientes drogas: mefloquina, quinidina, clindamicina y cotrimoxazol.The purpose of this paper is to present the cases of malaria caused by Plasmodium falciparum in travelers coming from tropical Africa, who were treated at the Hospital Alemán (Buenos Aires. African malaria was defined as an infection acquired in any country within Africa, diagnosed and treated in Argentina. Diagnostic tools included clinical features and optic microscopy with Giemsa stained peripheral blood films. We reviewed the medical records of 11 adult patients -five tourists and six sailors- with no history of malaria

  20. Optimization of the Conditions for Extraction of Serine Protease from Kesinai Plant (Streblus asper Leaves Using Response Surface Methodology

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    Md. Zaidul Islam Sarker

    2011-11-01

    Full Text Available Response surface methodology (RSM using a central composite design (CCD was employed to optimize the conditions for extraction of serine protease from kesinai (Streblus asper leaves. The effect of independent variables, namely temperature (42.5,47.5, X1, mixing time (2–6 min, X2, buffer content (0–80 mL, X3 and buffer pH (4.5–10.5, X4 on specific activity, storage stability, temperature and oxidizing agent stability of serine protease from kesinai leaves was investigated. The study demonstrated that use of the optimum temperature, mixing time, buffer content and buffer pH conditions protected serine protease during extraction, as demonstrated by low activity loss. It was found that the interaction effect of mixing time and buffer content improved the serine protease stability, and the buffer pH had the most significant effect on the specific activity of the enzyme. The most desirable conditions of 2.5 °C temperature, 4 min mixing time, 40 mL buffer at pH 7.5 was established for serine protease extraction from kesinai leaves.

  1. Confirmation of emergence of mutations associated with atovaquone-proguanil resistance in unexposed Plasmodium falciparum isolates from Africa

    Directory of Open Access Journals (Sweden)

    Kyle Dennis E

    2006-10-01

    Full Text Available Abstract Background In vitro and in vivo resistance of Plasmodium falciparum to atovaquone or atovaquone-proguanil hydrochloride combination has been associated to two point mutations in the parasite cytochrome b (cytb gene (Tyr268Ser and Tyr268Asn. However, little is known about the prevalence of codon-268 mutations in natural populations of P. falciparum without previous exposure to the drug in Africa. Methods The prevalence of codon-268 mutations in the cytb gene of African P. falciparum isolates from Nigeria, Malawi and Senegal, where atovaquone-proguanil has not been introduced for treatment of malaria was assessed. Genotyping of the cytb gene in isolates of P. falciparum was performed by PCR-restriction fragment length polymorphism and confirmed by sequencing. Results 295 samples from Nigeria (111, Malawi (91 and Senegal (93 were successfully analyzed for detection of either mutant Tyr268Ser or Tyr268Asn. No case of Ser268 or Asn268 was detected in cytb gene of parasites from Malawi or Senegal. However, Asn268 was detected in five out of 111 (4.5% unexposed P. falciparum isolates from Nigeria. In addition, one out of these five mutant Asn268 isolates showed an additional cytb mutation leading to a Pro266Thr substitution inside the ubiquinone reduction site. Conclusion No Tyr268Ser mutation is found in cytb of P. falciparum isolates from Nigeria, Malawi or Senegal. This study reports for the first time cytb Tyr268Asn mutation in unexposed P. falciparum isolates from Nigeria. The emergence in Africa of P. falciparum isolates with cytb Tyr268Asn mutation is a matter of serious concern. Continuous monitoring of atovaquone-proguanil resistant P. falciparum in Africa is warranted for the rational use of this new antimalarial drug, especially in non-immune travelers.

  2. Confirmation of emergence of mutations associated with atovaquone-proguanil resistance in unexposed Plasmodium falciparum isolates from Africa.

    Science.gov (United States)

    Happi, Christian T; Gbotosho, Grace O; Folarin, Onikepe A; Milner, Danny; Sarr, Ousmane; Sowunmi, Akintunde; Kyle, Dennis E; Milhous, Wilbur K; Wirth, Dyann F; Oduola, Ayoade M J

    2006-10-04

    In vitro and in vivo resistance of Plasmodium falciparum to atovaquone or atovaquone-proguanil hydrochloride combination has been associated to two point mutations in the parasite cytochrome b (cytb) gene (Tyr268Ser and Tyr268Asn). However, little is known about the prevalence of codon-268 mutations in natural populations of P. falciparum without previous exposure to the drug in Africa. The prevalence of codon-268 mutations in the cytb gene of African P. falciparum isolates from Nigeria, Malawi and Senegal, where atovaquone-proguanil has not been introduced for treatment of malaria was assessed. Genotyping of the cytb gene in isolates of P. falciparum was performed by PCR-restriction fragment length polymorphism and confirmed by sequencing. 295 samples from Nigeria (111), Malawi (91) and Senegal (93) were successfully analyzed for detection of either mutant Tyr268Ser or Tyr268Asn. No case of Ser268 or Asn268 was detected in cytb gene of parasites from Malawi or Senegal. However, Asn268 was detected in five out of 111 (4.5%) unexposed P. falciparum isolates from Nigeria. In addition, one out of these five mutant Asn268 isolates showed an additional cytb mutation leading to a Pro266Thr substitution inside the ubiquinone reduction site. No Tyr268Ser mutation is found in cytb of P. falciparum isolates from Nigeria, Malawi or Senegal. This study reports for the first time cytb Tyr268Asn mutation in unexposed P. falciparum isolates from Nigeria. The emergence in Africa of P. falciparum isolates with cytb Tyr268Asn mutation is a matter of serious concern. Continuous monitoring of atovaquone-proguanil resistant P. falciparum in Africa is warranted for the rational use of this new antimalarial drug, especially in non-immune travelers.

  3. Molecular cloning, expression and characterization of a serine proteinase inhibitor gene from Entamoeba histolytica.

    Science.gov (United States)

    Riahi, Yael; Siman-Tov, Rama; Ankri, Serge

    2004-02-01

    Serine proteinase inhibitors (serpins) are irreversible suicide inhibitors of proteinases that regulate a wide range of biological processes, including pathogen evasion of the host defence system. We report the cloning and characterization of a gene encoding a serpin from the protozoan parasite Entamoeba histolytica (Ehserp) that may function in this manner. The protein encoded by Ehserp contains 371 amino acids with a predicted mass of 42.6 kDa. Antibodies to a 42 kDa recombinant Ehserp react specifically with two bands of 42 and 49 kDa in trophozoite extracts. Ehserp has a cytoplasmic localization and is secreted by trophozoites incubated in the presence of mammalian cells, but not by resting trophozoites. A panel of mammalian serine proteinases was screened, but none of them was inhibited by the recombinant Ehserp. In contrast, the 49 kDa Ehserp present in the secretion product (SP) of activated macrophages interacted with human neutrophil cathepsin G to form a complex resistant to sodium dodecyl sulphate. We discuss the nature of the 42 and 49 kDa Ehserp and the possible roles that Ehserp may play in the survival of the parasite inside the host.

  4. A novel serine protease with human fibrino(geno)lytic activities from Artocarpus heterophyllus latex.

    Science.gov (United States)

    Siritapetawee, Jaruwan; Thumanu, Kanjana; Sojikul, Punchapat; Thammasirirak, Sompong

    2012-07-01

    A protease was isolated and purified from Artocarpus heterophyllus (jackfruit) latex and designated as a 48-kDa antimicrobial protease (AMP48) in a previous publication. In this work, the enzyme was characterized for more biochemical and medicinal properties. Enzyme activity of AMP48 was strongly inhibited by phenylmethanesulfonyl fluoride and soybean trypsin inhibitor, indicating that the enzyme was a plant serine protease. The N-terminal amino acid sequences (A-Q-E-G-G-K-D-D-D-G-G) of AMP48 had no sequence similarity matches with any sequence databases of BLAST search and other plant serine protease. The secondary structure of this enzyme was composed of high α-helix (51%) and low β-sheet (9%). AMP48 had fibrinogenolytic activity with maximal activity between 55 and 60°C at pH 8. The enzyme efficiently hydrolyzed α followed by partially hydrolyzed β and γ subunits of human fibrinogen. In addition, the fibrinolytic activity was observed through the degradation products by SDS-PAGE and emphasized its activity by monitoring the alteration of secondary structure of fibrin clot after enzyme digestion using ATR-FTIR spectroscopy. This study presented the potential role to use AMP48 as antithrombotic for treatment thromboembolic disorders such as strokes, pulmonary emboli and deep vein thrombosis. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Chromatin-Bound MDM2 Regulates Serine Metabolism and Redox Homeostasis Independently of p53.

    Science.gov (United States)

    Riscal, Romain; Schrepfer, Emilie; Arena, Giuseppe; Cissé, Madi Y; Bellvert, Floriant; Heuillet, Maud; Rambow, Florian; Bonneil, Eric; Sabourdy, Frédérique; Vincent, Charles; Ait-Arsa, Imade; Levade, Thierry; Thibaut, Pierre; Marine, Jean-Christophe; Portais, Jean-Charles; Sarry, Jean-Emmanuel; Le Cam, Laurent; Linares, Laetitia K

    2016-06-16

    The mouse double minute 2 (MDM2) oncoprotein is recognized as a major negative regulator of the p53 tumor suppressor, but growing evidence indicates that its oncogenic activities extend beyond p53. Here, we show that MDM2 is recruited to chromatin independently of p53 to regulate a transcriptional program implicated in amino acid metabolism and redox homeostasis. Identification of MDM2 target genes at the whole-genome level highlights an important role for ATF3/4 transcription factors in tethering MDM2 to chromatin. MDM2 recruitment to chromatin is a tightly regulated process that occurs during oxidative stress and serine/glycine deprivation and is modulated by the pyruvate kinase M2 (PKM2) metabolic enzyme. Depletion of endogenous MDM2 in p53-deficient cells impairs serine/glycine metabolism, the NAD(+)/NADH ratio, and glutathione (GSH) recycling, impacting their redox state and tumorigenic potential. Collectively, our data illustrate a previously unsuspected function of chromatin-bound MDM2 in cancer cell metabolism. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Realizing Serine/Threonine Ligation: Scope and Limitations and Mechanistic Implication Thereof

    Directory of Open Access Journals (Sweden)

    Clarence T. T. Wong

    2014-05-01

    Full Text Available Serine/Threonine ligation (STL has emerged as an alternative tool for protein chemical synthesis, bioconjugations as well as macrocyclization of peptides of various sizes. Owning to the high abundance of Ser/Thr residues in natural peptides and proteins, STL is expected to find a wide range of applications in chemical biology research. Herein, we have fully investigated the compatibility of the serine/threonine ligation strategy for X-Ser/Thr ligation sites, where X is any of the 20 naturally occurring amino acids. Our studies have shown that 17 amino acids are suitable for ligation, while Asp, Glu, and Lys are not compatible. Among the working 17 C-terminal amino acids, the retarded reaction resulted from the bulky β-branched amino acid (Thr, Val and Ile is not seen under the current ligation condition. We have also investigated the chemoselectivity involving the amino group of the internal lysine which may compete with the N-terminal Ser/Thr for reaction with the C-terminal salicylaldehyde (SAL ester aldehyde group. The result suggested that the free internal amino group does not adversely slow down the ligation rate.

  7. Characterization of Toxoplasma DegP, a rhoptry serine protease crucial for lethal infection in mice.

    Directory of Open Access Journals (Sweden)

    Gaelle Lentini

    Full Text Available During the infection process, Apicomplexa discharge their secretory organelles called micronemes, rhoptries and dense granules to sustain host cell invasion, intracellular replication and to modulate host cell pathways and immune responses. Herein, we describe the Toxoplasma gondii Deg-like serine protein (TgDegP, a rhoptry protein homologous to High temperature requirement A (HtrA or Deg-like family of serine proteases. TgDegP undergoes processing in both types I and II strains as most of the rhoptries proteins. We show that genetic disruption of the degP gene does not impact the parasite lytic cycle in vitro but affects virulence in mice. While in a type I strain DegPI appears dispensable for the establishment of an infection, removal of DegPII in a type II strain dramatically impairs the virulence. Finally, we show that KO-DegPII parasites kill immunodeficient mice as efficiently as the wild-type strain indicating that the protease might be involved in the complex crosstalk that the parasite engaged with the host immune response. Thus, this study unravels a novel rhoptry protein in T. gondii important for the establishment of lethal infection.

  8. Novel Serine 176 Phosphorylation of YBX1 Activates NF-κB in Colon Cancer.

    Science.gov (United States)

    Martin, Matthew; Hua, Laiqing; Wang, Benlian; Wei, Han; Prabhu, Lakshmi; Hartley, Antja-Voy; Jiang, Guanglong; Liu, Yunlong; Lu, Tao

    2017-02-24

    Y box protein 1 (YBX1) is a well known oncoprotein that has tumor-promoting functions. YBX1 is widely considered to be an attractive therapeutic target in cancer. To develop novel therapeutics to target YBX1, it is of great importance to understand how YBX1 is finely regulated in cancer. Previously, we have shown that YBX1 could function as a tumor promoter through phosphorylation of its Ser-165 residue, leading to the activation of the NF-κB signaling pathway (1). In this study, using mass spectrometry analysis, we discovered a distinct phosphorylation site, Ser-176, on YBX1. Overexpression of the YBX1-S176A (serine-to-alanine) mutant in either HEK293 cells or colon cancer HT29 cells showed dramatically reduced NF-κB-activating ability compared with that of WT-YBX1, confirming that Ser-176 phosphorylation is critical for the activation of NF-κB by YBX1. Importantly, the mutant of Ser-176 and the previously reported Ser-165 sites regulate distinct groups of NF-κB target genes, suggesting the unique and irreplaceable function of each of these two phosphorylated serine residues. Our important findings could provide a novel cancer therapy strategy by blocking either Ser-176 or Ser-165 phosphorylation or both of YBX1 in colon cancer. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Portulaca oleracea L. as a Prospective Candidate Inhibitor of Hepatitis C Virus NS3 Serine Protease.

    Science.gov (United States)

    Noreen, Sobia; Hussain, Ishtiaq; Tariq, Muhammad Ilyas; Ijaz, Bushra; Iqbal, Shahid; Qamar-ul-Zaman; Ashfaq, Usman Ali; Husnain, Tayyab

    2015-06-01

    Hepatitis C virus (HCV) infection is a worldwide health problem affecting about 300 million individuals. HCV causes chronic liver disease, liver cirrhosis, hepatocellular carcinoma, and death. Many side effects are associated with the current treatment options. Natural products that can be used as anti-HCV drugs are thus of considerable potential significance. NS3 serine protease (NS3-SP) is a target for the screening of antiviral activity against HCV. The present work explores plants with anti-HCV potential, isolating possible lead compounds. Ten plants, used for medicinal purposes against different infections in rural areas of Pakistan, were collected. The cellular toxicity effects of methanolic extracts of the plants on the viability of Huh-7 cells were studied through the Trypan blue dye exclusion method. Following this, the anti-HCV potential of phytoextracts was assessed by infecting liver cells with HCV-3a-infected serum inoculum. Only the methanolic extract of Portulaca oleracea L. (PO) exhibited more than 70% inhibition. Four fractions were obtained through bioassay-guided extraction of PO. Subsequent inhibition of all organic extract fractions against NS3 serine protease was checked to track the specific target in the virus. The results showed that the PO methanolic crude and ethyl acetate extract specifically abridged the HCV NS3 protease expression in a dose-dependent fashion. Hence, PO extract and its constituents either alone or with interferon could offer a future option to treat chronic HCV.

  10. Structure Determination of Mycobacterium tuberculosis Serine Protease Hip1 (Rv2224c)

    Energy Technology Data Exchange (ETDEWEB)

    Naffin-Olivos, Jacqueline L.; Daab, Andrew; White, Andre; Goldfarb, Nathan E.; Milne, Amy C.; Liu, Dali; Baikovitz, Jacqueline; Dunn, Ben M.; Rengarajan, Jyothi; Petsko, Gregory A.; Ringe, Dagmar

    2017-04-07

    The Mycobacterium tuberculosis (Mtb) serine protease Hip1 (hydrolase important for pathogenesis; Rv2224c) promotes tuberculosis (TB) pathogenesis by impairing host immune responses through proteolysis of a protein substrate, Mtb GroEL2. The cell surface localization of Hip1 and its immunomodulatory functions make Hip1 a good drug target for new adjunctive immune therapies for TB. Here, we report the crystal structure of Hip1 to a resolution of 2.6 Å and the kinetic studies of the enzyme against model substrates and the protein GroEL2. The structure shows a two-domain protein, one of which contains the catalytic residues that are the signature of a serine protease. Surprisingly, a threonine is located within the active site close enough to hydrogen bond with the catalytic residues Asp463 and His490. Mutation of this residue, Thr466, to alanine established its importance for function. Our studies provide insights into the structure of a member of a novel family of proteases. Knowledge of the Hip1 structure will aid in designing inhibitors that could block Hip1 activity

  11. Antiviral activity of a serine protease from the digestive juice of Bombyx mori larvae against nucleopolyhedrovirus

    International Nuclear Information System (INIS)

    Nakazawa, Hiroshi; Tsuneishi, Eiko; Ponnuvel, Kangayam M.; Furukawa, Seiichi; Asaoka, Ai; Tanaka, Hiromitsu; Ishibashi, Jun; Yamakawa, Minoru

    2004-01-01

    A protein showing strong antiviral activity against Bombyx mori nucleopolyhedrovirus (BmNPV) was purified from the digestive juice of B. mori larvae. The molecular mass of this protein was 24 271 Da. Partial N-terminal amino acid sequence of the protein was determined and cDNA was cloned based on the amino acid sequence. A homology search of the deduced amino acid sequence of the cDNA showed 94% identity with B. mori serine protease so the protein was designated B. mori serine protease-2 (BmSP-2). Analysis of BmSP-2 gene expression showed that this gene is expressed in the midgut but not in other tissues. In addition, BmSP-2 gene was shown to not be expressed in the molting and wandering stages, indicating that the gene is hormonally regulated. Our results suggest that BmSP-2, an insect digestive enzyme, can be a potential antiviral factor against BmNPV at the initial site of viral infection

  12. Purification and biochemical characterization of the haloalkaliphilic archaeon Natronococcus occultus extracellular serine protease

    DEFF Research Database (Denmark)

    Studdert, C A; Herrera Seitz, M K; Plasencia, I

    2001-01-01

    A serine protease was purified from Natronococcus occultus stationary phase culture medium (328-fold, yield 19%) and characterized at the biochemical level. The enzyme has a native molecular mass of 130 kDa, has chymotrypsin-like activity, is stable and active in a broad pH range (5.5-12), is rat......A serine protease was purified from Natronococcus occultus stationary phase culture medium (328-fold, yield 19%) and characterized at the biochemical level. The enzyme has a native molecular mass of 130 kDa, has chymotrypsin-like activity, is stable and active in a broad pH range (5.......5-12), is rather thermophilic (optimal activity at 60 degrees C in 1-2 M NaCl) and is dependent on high salt concentrations for activity and stability (1-2 M NaCl or KCl). Polyclonal antibodies were raised against the purified protease. In Western blots, they presented no cross-reactivity with culture medium from...... other halobacteria nor with commercial proteases except subtilisin. The amino acid sequences of three tryptic peptides obtained from Natronococcus occultus protease did not show significant similarity to other known proteolytic enzymes. This fact, in addition to its high molecular mass suggests...

  13. Detection systems for carbapenemase gene identification should include the SME serine carbapenemase.

    Science.gov (United States)

    Bush, Karen; Pannell, Megan; Lock, John L; Queenan, Anne Marie; Jorgensen, James H; Lee, Ryan M; Lewis, James S; Jarrett, Deidre

    2013-01-01

    Carbapenemase detection has become a major problem in hospitals that encounter outbreaks of infections caused by carbapenem-resistant Gram-negative bacteria. Rapid detection systems have been reported using multiplex PCR analyses and DNA microarray assays. Major carbapenemases that are detected by these systems include the KPC and OXA serine carbapenemases, and the IMP, VIM and NDM families of metallo-β-lactamases. However, increasing numbers of the SME serine carbapenemase are being reported from Serratia marcescens, especially from North and South America. These organisms differ from many of the other carbapenemase-producing pathogens in that they are generally susceptible to the expanded-spectrum cephalosporins ceftazidime and cefepime while retaining resistance to almost all other β-lactam antibiotics. Thus, multiplex PCR assays or DNA microarray testing of carbapenem-resistant S. marcescens isolates should include analyses for production of the SME carbapenemase. Confirmation of the presence of this enzyme may provide reassurance that oxyimino-cephalosporins can be considered for treatment of infections caused by these carbapenem-resistant pathogens. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  14. Two novel pyrrolooxazole pigments formed by the Maillard reaction between glucose and threonine or serine.

    Science.gov (United States)

    Noda, Kyoko; Murata, Masatsune

    2017-02-01

    Pyrrolothiazolate formed by the Maillard reaction between l-cysteine and d-glucose has a pyrrolothiazole skeleton as a chromophore. We searched for a Maillard pigment having a pyrrolooxazole skeleton formed from l-threonine or l-serine instead of l-cysteine in the presence of d-glucose. As a result, two novel yellow pigments, named pyrrolooxazolates A and B, were isolated from model solutions of the Maillard reaction containing l-threonine and d-glucose, and l-serine and d-glucose, respectively, and identified as (2R,3S,7aS)-2,3,7,7a-tetrahydro-6-hydroxy-2,5,7a-trimethyl-7-oxo-pyrrolo[2,1-b]oxazole-3-calboxylic acid and (3S,7aS)-2,3,7,7a-tetrahydro-6-hydroxy-5,7a-dimethyl-7-oxo-pyrrolo[2,1-b]oxazole-3-calboxylic acid by instrumental analyses. These compounds were pyrrolooxazole derivatives carrying a carboxy group, and showed the absorption maxima at 300-360 nm under acidic and neutral conditions and at 320-390 nm under alkaline conditions.

  15. Characterization of a membrane-associated serine protease in Escherichia coli

    International Nuclear Information System (INIS)

    Palmer, S.M.; St John, A.C.

    1987-01-01

    Three membrane-associated proteolytic activities in Escherichia coli were resolved by DEAE-cellulose chromatography from detergent extracts of the total envelope fraction. On the basis of substrate specificity for the hydrolysis of chromogenic amino acid ester substrates, the first two eluting activities were determined previously to be protease V and protease IV, respectively. The third proteolytic activity eluting from the DEAE-cellulose column was further purified by affinity chromatography on benzamidine-Sepharose 6B. They termed this enzyme protease VI. Protease VI did not hydrolyze any of the chromogenic substrates used in the detection of protease IV and protease V. However, all three enzymes generated acid-soluble fragments from a mixture of E. coli membrane proteins which were biosynthetically labeled with radioactive amino acids. The activity of protease VI was sensitive to serine protease inhibitors. Using [ 3 H]diisopropylfluorophosphate as an active-site labeling reagent, they determined that protease VI has an apparent molecular weight of 43,000 in polyacrylamide gels. All three membrane-associated serine proteases were insensitive to inhibition by Ecotin, an endogenous, periplasmic inhibitor of trypsin

  16. Systematic Survey of Serine Hydrolase Activity in Mycobacterium tuberculosis Defines Changes Associated with Persistence

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Corrie; Anderson, Lindsey N.; Frando, Andrew; Sadler, Natalie C.; Brown, Robert W.; Smith, Richard D.; Wright, Aaron T.; Grundner, Christoph

    2016-02-01

    The transition between replication and non-replication underlies much of Mycobacterium tuberculosis (Mtb) pathogenicity, as non- or slowly replicating Mtb are responsible for persistence and poor treatment outcomes. Therapeutic targeting of non-replicating, persistent populations is a priority for tuberculosis treatment, but only few drug targets in non-replicating Mtb are currently known. Here, we directly measure the activity of the highly diverse and druggable serine hydrolases (SHs) during active replication and non-replication by activity-based proteomics. We predict serine hydrolase activity for 78 proteins, including 27 proteins with previously unknown function, and identify 37 SHs that remain active even in the absence of replication, providing a set of candidate persistence targets. Non-replication was associated with large shifts in the activity of the majority of SHs. These activity changes were largely independent of SH abundance, indicating extensive post-translational regulation. By probing a large cross-section of druggable Mtb enzyme space during replication and non-replication, we identify new SHs and suggest new persistence targets.

  17. Interaction of protein C inhibitor with the type II transmembrane serine protease enteropeptidase.

    Directory of Open Access Journals (Sweden)

    Thomas A Prohaska

    Full Text Available The serine protease inhibitor protein C inhibitor (PCI is expressed in many human tissues and exhibits broad protease reactivity. PCI binds glycosaminoglycans and certain phospholipids, which modulate its inhibitory activity. Enteropeptidase (EP is a type II transmembrane serine protease mainly found on the brush border membrane of epithelial cells in the duodenum, where it activates trypsinogen to initiate the digestion of food proteins. Some active EP is also present in duodenal fluid and has been made responsible for causing pancreatitis in case of duodeno-pancreatic reflux. Together with its substrate trypsinogen, EP is furthermore present in the epidermis and in some cancer cells. In this report, we show that PCI inhibited EP with an apparent 2nd order rate constant of 4.48 × 10(4 M(-1 s(-1. Low molecular weight (LMWH and unfractionated heparin (UFH slightly reduced the inhibitory effect of PCI. The SI (stoichiometry of inhibition value for the inhibition of EP by PCI was 10.8 in the absence and 17.9 in the presence of UFH (10 U/ml. By inhibiting trypsin, chymotrypsin, and additionally EP, PCI might play a role in the protection of the pancreas from autodigestion. Furthermore the interaction of PCI with EP may influence the regulation of epithelial differentiation.

  18. Serine proteases as candidates for proteolytic processing of angiotensin-I converting enzyme.

    Science.gov (United States)

    Aragão, Danielle S; de Andrade, Maria Claudina C; Ebihara, Fabiana; Watanabe, Ingrid K M; Magalhães, Dayane C B P; Juliano, Maria Aparecida; Hirata, Izaura Yoshico; Casarini, Dulce Elena

    2015-01-01

    Somatic angiotensin-I converting enzyme (sACE) is a broadly distributed peptidase which plays a role in blood pressure and electrolyte homeostasis by the conversion of angiotensin I into angiotensin II. N-domain isoforms (nACE) with 65 and 90 kDa have been described in body fluids, tissues and mesangial cells (MC), and a 90 kDa nACE has been described only in spontaneously hypertensive rats. The aim of this study was to investigate the existence of proteolytic enzymes that may act in the hydrolysis of sACE generating nACEs in MC. After the confirmation of the presence of ACE sheddases in Immortalized MC (IMC), we purified and characterized these enzymes using fluorogenic substrates specifically designed for ACE sheddases. Purified enzyme identified as a serine protease by N-terminal sequence was able to generate nACE. In the present study, we described for the first time the presence of ACE sheddases in IMC, identified as serine proteases able to hydrolyze sACE in vitro. Further investigations are necessary to elucidate the mechanisms responsible for the expression and regulation of ACE sheddases in MC and their roles in the generation of nACEs, especially the 90 kDa form possibly related to hypertension. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Structural and Functional Adaptation of Vancomycin Resistance VanT Serine Racemases.

    Science.gov (United States)

    Meziane-Cherif, Djalal; Stogios, Peter J; Evdokimova, Elena; Egorova, Olga; Savchenko, Alexei; Courvalin, Patrice

    2015-08-11

    Vancomycin resistance in Gram-positive bacteria results from the replacement of the D-alanyl-D-alanine target of peptidoglycan precursors with D-alanyl-D-lactate or D-alanyl-D-serine (D-Ala-D-Ser), to which vancomycin has low binding affinity. VanT is one of the proteins required for the production of D-Ala-D-Ser-terminating precursors by converting L-Ser to D-Ser. VanT is composed of two domains, an N-terminal membrane-bound domain, likely involved in L-Ser uptake, and a C-terminal cytoplasmic catalytic domain which is related to bacterial alanine racemases. To gain insight into the molecular function of VanT, the crystal structure of the catalytic domain of VanTG from VanG-type resistant Enterococcus faecalis BM4518 was determined. The structure showed significant similarity to type III pyridoxal 5'-phosphate (PLP)-dependent alanine racemases, which are essential for peptidoglycan synthesis. Comparative structural analysis between VanTG and alanine racemases as well as site-directed mutagenesis identified three specific active site positions centered around Asn696 which are responsible for the L-amino acid specificity. This analysis also suggested that VanT racemases evolved from regular alanine racemases by acquiring additional selectivity toward serine while preserving that for alanine. The 4-fold-lower relative catalytic efficiency of VanTG against L-Ser versus L-Ala implied that this enzyme relies on its membrane-bound domain for L-Ser transport to increase the overall rate of d-Ser production. These findings illustrate how vancomycin pressure selected for molecular adaptation of a housekeeping enzyme to a bifunctional enzyme to allow for peptidoglycan remodeling, a strategy increasingly observed in antibiotic-resistant bacteria. Vancomycin is one of the drugs of last resort against Gram-positive antibiotic-resistant pathogens. However, bacteria have evolved a sophisticated mechanism which remodels the drug target, the D-alanine ending precursors in cell wall

  20. Combination atovaquone and proguanil hydrochloride vs. halofantrine for treatment of acute Plasmodium falciparum malaria in children.

    Science.gov (United States)

    Anabwani, G; Canfield, C J; Hutchinson, D B

    1999-05-01

    Malaria is a major cause of pediatric mortality in sub-Saharan Africa. Worldwide estimates of mortality among children with Plasmodium falciparum malaria range from 1 to 2 million deaths per year. Management of malaria is increasingly difficult because of the global spread of drug-resistant strains of P. falciparum. There is an urgent need for safe and effective new therapies to treat multidrug-resistant malaria. This open label, randomized trial compared atovaquone and proguanil hydrochloride with halofantrine for treatment of acute, uncomplicated P. falciparum malaria in children age 3 to 12 years (84 patients per group). Study drug dosages were adjusted by weight (approximately 20 and 8 mg/kg daily for three doses for atovaquone and proguanil hydrochloride and 8 mg/kg every 6 h for three doses for halofantrine). Patients were monitored by serial clinical and laboratory assessments for 28 days after starting treatment. Both regimens were effective (cure rate, 93.8% for atovaquone and proguanil hydrochloride and 90.4% for halofantrine) and produced prompt defervescence. Mean parasite clearance times were 50.2 h for halofantrine and 64.9 h for atovaquone and proguanil hydrochloride. More adverse experiences were reported in children treated with halofantrine (119) than with atovaquone and proguanil hydrochloride (73). In Kenyan children the combination of atovaquone and proguanil hydrochloride has efficacy comparable with that of halofantrine for treatment of acute uncomplicated multidrug-resistant falciparum malaria and is associated with a lower rate of adverse events.

  1. Direct whole-genome sequencing of Plasmodium falciparum specimens from dried erythrocyte spots

    DEFF Research Database (Denmark)

    Nag, Sidsel; Kofoed, Poul Erik; Ursing, Johan

    2018-01-01

    -infected individuals living in rural areas, away from main infrastructure and the electrical grid. The aim of this study was to describe a low-tech procedure to sample P. falciparum specimens for direct whole genome sequencing (WGS), without use of electricity and cold-chain. Methods: Venous blood samples were...

  2. Protein export marks the early phase of gametocytogenesis of the human malaria parasite Plasmodium falciparum.

    NARCIS (Netherlands)

    Silvestrini, F.; Lasonder, E.; Olivieri, A.; Camarda, G.; Schaijk, B.C.L. van; Sanchez, M.; Younis Younis, S.; Sauerwein, R.W.; Alano, P.

    2010-01-01

    Despite over a century of study of malaria parasites, parts of the Plasmodium falciparum life cycle remain virtually unknown. One of these is the early gametocyte stage, a round shaped cell morphologically similar to an asexual trophozoite in which major cellular transformations ensure subsequent

  3. Cytometric quantification of singlet oxygen in the human malaria parasite Plasmodium falciparum

    NARCIS (Netherlands)

    Butzloff, Sabine; Groves, Matthew R; Wrenger, Carsten; Müller, Ingrid B

    The malaria parasite Plasmodium falciparum proliferates within human erythrocytes and is thereby exposed to a variety of reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical, superoxide anion, and highly reactive singlet oxygen ((1)O(2)). While most ROS are already well studied

  4. Analysis of the plasmodium falciparum proteome by high-accuracy mass spectrometry

    DEFF Research Database (Denmark)

    Lasonder, Edwin; Ishihama, Yasushi; Andersen, Jens S

    2002-01-01

    -accuracy (average deviation less than 0.02 Da at 1,000 Da) mass spectrometric proteome analysis of selected stages of the human malaria parasite Plasmodium falciparum. The analysis revealed 1,289 proteins of which 714 proteins were identified in asexual blood stages, 931 in gametocytes and 645 in gametes. The last...

  5. Controlled Human Malaria Infection of Tanzanians by Intradermal Injection of Aseptic, Purified, Cryopreserved Plasmodium falciparum Sporozoites

    NARCIS (Netherlands)

    Shekalaghe, S.; Rutaihwa, M.; Billingsley, P.F.; Chemba, M.; Daubenberger, C.A.; James, E.R.; Mpina, M.; Juma, O. Ali; Schindler, T.; Huber, E.; Gunasekera, A.; Manoj, A.; Simon, B.; Saverino, E.; Church, L.W.; Hermsen, C.C.; Sauerwein, R.W.; Plowe, C.; Venkatesan, M.; Sasi, P.; Lweno, O.; Mutani, P.; Hamad, A.; Mohammed, A.; Urassa, A.; Mzee, T.; Padilla, D.; Ruben, A.; Sim, B.K.; Tanner, M.; Abdulla, S.; Hoffman, S.L.

    2014-01-01

    Controlled human malaria infection (CHMI) by mosquito bite has been used to assess anti-malaria interventions in > 1,500 volunteers since development of methods for infecting mosquitoes by feeding on Plasmodium falciparum (Pf) gametocyte cultures. Such CHMIs have never been used in Africa. Aseptic,

  6. The exported chaperone Hsp70-x supports virulence functions for Plasmodium falciparum blood stage parasites.

    Directory of Open Access Journals (Sweden)

    Sarah C Charnaud

    Full Text Available Malaria is caused by five different Plasmodium spp. in humans each of which modifies the host erythrocyte to survive and replicate. The two main causes of malaria, P. falciparum and P. vivax, differ in their ability to cause severe disease, mainly due to differences in the cytoadhesion of infected erythrocytes (IE in the microvasculature. Cytoadhesion of P. falciparum in the brain leads to a large number of deaths each year and is a consequence of exported parasite proteins, some of which modify the erythrocyte cytoskeleton while others such as PfEMP1 project onto the erythrocyte surface where they bind to endothelial cells. Here we investigate the effects of knocking out an exported Hsp70-type chaperone termed Hsp70-x that is present in P. falciparum but not P. vivax. Although the growth of Δhsp70-x parasites was unaffected, the export of PfEMP1 cytoadherence proteins was delayed and Δhsp70-x IE had reduced adhesion. The Δhsp70-x IE were also more rigid than wild-type controls indicating changes in the way the parasites modified their host erythrocyte. To investigate the cause of this, transcriptional and translational changes in exported and chaperone proteins were monitored and some changes were observed. We propose that PfHsp70-x is not essential for survival in vitro, but may be required for the efficient export and functioning of some P. falciparum exported proteins.

  7. Relative Susceptibilities of ABO Blood Groups to Plasmodium falciparum Malaria in Ghana.

    Science.gov (United States)

    Afoakwah, Richmond; Aubyn, Edmond; Prah, James; Nwaefuna, Ekene Kwabena; Boampong, Johnson N

    2016-01-01

    The clinical outcome of falciparum malaria in endemic areas is influenced by erythrocyte polymorphisms including the ABO blood groups. Studies have reported association of ABO blood group to resistance, susceptibility, and severity of P. falciparum malaria infection. Individuals with blood group "A" have been found to be highly susceptible to falciparum malaria whereas blood group "O" is said to confer protection against complicated cases. We analyzed samples from 293 young children less than six years old with malaria in the Korle-Bu Teaching Hospital in Accra, Ghana. It was observed that group O was present in about 16.1% of complicated cases weighed against 40.9% of uncomplicated controls. Individuals with complicated malaria were about twice likely to be of blood groups A and B compared to group O (A versus O, OR = 1.90, 95% CI = 1.59-2.26, P Blood group O participants with complicated diseases had low parasitaemia compared to the other blood groups (P blood group O individuals a survival advantage over the other groups in complicated malaria as suggested. Participants with complicated falciparum malaria were generally anaemic and younger than those with uncomplicated disease.

  8. The exported chaperone Hsp70-x supports virulence functions for Plasmodium falciparum blood stage parasites

    Science.gov (United States)

    Charnaud, Sarah C.; Dixon, Matthew W. A.; Nie, Catherine Q.; Chappell, Lia; Sanders, Paul R.; Nebl, Thomas; Hanssen, Eric; Berriman, Matthew; Chan, Jo-Anne; Blanch, Adam J.; Beeson, James G.; Rayner, Julian C.; Przyborski, Jude M.; Tilley, Leann; Crabb, Brendan S.

    2017-01-01

    Malaria is caused by five different Plasmodium spp. in humans each of which modifies the host erythrocyte to survive and replicate. The two main causes of malaria, P. falciparum and P. vivax, differ in their ability to cause severe disease, mainly due to differences in the cytoadhesion of infected erythrocytes (IE) in the microvasculature. Cytoadhesion of P. falciparum in the brain leads to a large number of deaths each year and is a consequence of exported parasite proteins, some of which modify the erythrocyte cytoskeleton while others such as PfEMP1 project onto the erythrocyte surface where they bind to endothelial cells. Here we investigate the effects of knocking out an exported Hsp70-type chaperone termed Hsp70-x that is present in P. falciparum but not P. vivax. Although the growth of Δhsp70-x parasites was unaffected, the export of PfEMP1 cytoadherence proteins was delayed and Δhsp70-x IE had reduced adhesion. The Δhsp70-x IE were also more rigid than wild-type controls indicating changes in the way the parasites modified their host erythrocyte. To investigate the cause of this, transcriptional and translational changes in exported and chaperone proteins were monitored and some changes were observed. We propose that PfHsp70-x is not essential for survival in vitro, but may be required for the efficient export and functioning of some P. falciparum exported proteins. PMID:28732045

  9. Plasmodium falciparum mutant haplotype infection during pregnancy associated with reduced birthweight, Tanzania

    DEFF Research Database (Denmark)

    Minja, Daniel T R; Schmiegelow, Christentze; Mmbando, Bruno

    2013-01-01

    Intermittent preventive treatment during pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) is a key strategy in the control of pregnancy-associated malaria. However, this strategy is compromised by widespread drug resistance from single-nucleotide polymorphisms in the Plasmodium falciparum...

  10. Immunogenicity and in vitro Protective Efficacy of a Recombinant Multistage Plasmodium falciparum Candidate Vaccine

    Science.gov (United States)

    Shi, Ya Ping; Hasnain, Seyed E.; Sacci, John B.; Holloway, Brian P.; Fujioka, Hisashi; Kumar, Nirbhay; Wohlhueter, Robert; Hoffman, Stephen L.; Collins, William E.; Lal, Altaf A.

    1999-02-01

    Compared with a single-stage antigen-based vaccine, a multistage and multivalent Plasmodium falciparum vaccine would be more efficacious by inducing "multiple layers" of immunity. We have constructed a synthetic gene that encodes for 12 B cell, 6 T cell proliferative, and 3 cytotoxic T lymphocyte epitopes derived from 9 stage-specific P. falciparum antigens corresponding to the sporozoite, liver, erythrocytic asexual, and sexual stages. The gene was expressed in the baculovirus system, and a 41-kDa antigen, termed CDC/NIIMALVAC-1, was purified. Immunization in rabbits with the purified protein in the presence of different adjuvants generated antibody responses that recognized vaccine antigen, linear peptides contained in the vaccine, and all stages of P. falciparum. In vitro assays of protection revealed that the vaccine-elicited antibodies strongly inhibited sporozoite invasion of hepatoma cells and growth of blood-stage parasites in the presence of monocytes. These observations demonstrate that a multicomponent, multistage malaria vaccine can induce immune responses that inhibit parasite development at multiple stages. The rationale and approach used in the development of a multicomponent P. falciparum vaccine will be useful in the development of a multispecies human malaria vaccine and vaccines against other infectious diseases.

  11. The efficacy of artemether in the treatment of Plasmodium falciparum malaria in Sudan

    DEFF Research Database (Denmark)

    Elhassan, I M; Satti, G H; Ali, A E

    1994-01-01

    The efficacy of artemether (a qinghaosu derivative) administered intramuscularly for the treatment of Plasmodium falciparum malaria was compared to quinine in an open randomized trial including 54 patients in eastern Sudan, where chloroquine resistance is common. The artemether treatment (5 d...

  12. Complete Plasmodium falciparum liver-stage development in liver-chimeric mice

    Science.gov (United States)

    Vaughan, Ashley M.; Mikolajczak, Sebastian A.; Wilson, Elizabeth M.; Grompe, Markus; Kaushansky, Alexis; Camargo, Nelly; Bial, John; Ploss, Alexander; Kappe, Stefan H.I.

    2012-01-01

    Plasmodium falciparum, which causes the most lethal form of human malaria, replicates in the host liver during the initial stage of infection. However, in vivo malaria liver-stage (LS) studies in humans are virtually impossible, and in vitro models of LS development do not reconstitute relevant parasite growth conditions. To overcome these obstacles, we have adopted a robust mouse model for the study of P. falciparum LS in vivo: the immunocompromised and fumarylacetoacetate hydrolase–deficient mouse (Fah–/–, Rag2–/–, Il2rg–/–, termed the FRG mouse) engrafted with human hepatocytes (FRG huHep). FRG huHep mice supported vigorous, quantifiable P. falciparum LS development that culminated in complete maturation of LS at approximately 7 days after infection, providing a relevant model for LS development in humans. The infections allowed observations of previously unknown expression of proteins in LS, including P. falciparum translocon of exported proteins 150 (PTEX150) and exported protein-2 (EXP-2), components of a known parasite protein export machinery. LS schizonts exhibited exoerythrocytic merozoite formation and merosome release. Furthermore, FRG mice backcrossed to the NOD background and repopulated with huHeps and human red blood cells supported reproducible transition from LS infection to blood-stage infection. Thus, these mice constitute reliable models to study human LS directly in vivo and demonstrate utility for studies of LS–to–blood-stage transition of a human malaria parasite. PMID:22996664

  13. Falciparum malaria transmitted by a thick blood smear negative kidney donor

    NARCIS (Netherlands)

    Bemelman, Frederike; de Blok, Koen; de Vries, Peter; Surachno, S.; ten Berge, Ineke

    2004-01-01

    This report describes a case of P. falciparum transmission by a recent-immigrant renal donor. The donor tested negative upon microscopy of a thick blood smear. The diagnosis was made after analysis of a Quantified Buffy Coat(R). In our opinion, a renal donor from a malaria endemic country should be

  14. Induction of cell death on Plasmodium falciparum asexual blood stages by Solanum nudum steroids

    DEFF Research Database (Denmark)

    López, Mary Luz; Vommaro, Rossiane; Zalis, Mariano

    2010-01-01

    Solanum nudum Dunal (Solanaceae) is a plant used in traditional medicine in Colombian Pacific Coast, from which five steroids denominated SNs have been isolated. The SNs compounds have antiplasmodial activity against asexual blood stages of Plasmodium falciparum strain 7G8 with an IC50 between 20...

  15. Comparison of oral artesunate and dihydroartemisinin antimalarial bioavailabilities in acute falciparum malaria

    NARCIS (Netherlands)

    Newton, Paul N.; van Vugt, Michele; Teja-Isavadharm, Paktiya; Siriyanonda, Duangsuda; Rasameesoroj, Maneerat; Teerapong, Pramote; Ruangveerayuth, Ronatrai; Slight, Thra; Nosten, Francois; Suputtamongkol, Yupin; Looareesuwan, Sornchai; White, Nicholas J.

    2002-01-01

    Plasma antimalarial activity following oral artesunate or dihydroartemisinin (DHA) treatment was measured by a bioassay in 18 patients with uncomplicated falciparum malaria. The mean antimalarial activity in terms of the bioavailability of DHA relative to that of artesunate did not differ

  16. Plasmodium falciparum-induced severe malaria with acute kidney injury and jaundice: a case report

    Science.gov (United States)

    Baswin, A.; Siregar, M. L.; Jamil, K. F.

    2018-03-01

    P. falciparum-induced severe malaria with life-threatening complications like acute kidney injury (AKI), jaundice, cerebral malaria, severe anemia, acidosis, and acute respiratory distress syndrome (ARDS). A 31-year-old soldier man who works in Aceh Singkil, Indonesia which is an endemic malaria area presented with a paroxysm of fever, shaking chills and sweats over four days, headache, arthralgia, abdominal pain, pale, jaundice, and oliguria. Urinalysis showed hemoglobinuria. Blood examination showed hemolytic anemia, thrombocytopenia, and hyperbilirubinemia. Falciparum malaria was then confirmed by peripheral blood smear, antimalarial medications were initiated, and hemodialysis was performed for eight times. The patient’s condition and laboratory results were quickly normalized. We report a case of P. falciparum-induced severe malaria with AKI and jaundice. The present case suggests that P. falciparum may induce severe malaria with life-threatening complications, early diagnosis and treatment is important to improve the quality of life of patients. Physicians must be alert for correct diagnosis and proper management of imported tropical malaria when patients have travel history in endemic areas.

  17. Lung uptake of /sup 99m/Tc--sulfur colloid in falciparum malaria: case report

    International Nuclear Information System (INIS)

    Ziessman, H.A.

    1976-01-01

    Increased lung uptake of /sup 99m/Tc-sulfur colloid was seen during liver scanning in a patient with falciparum malaria. This finding was due to the enhanced activity of the phagocytic cells of the reticuloendothelial system in the liver, spleen, and lung found in human and experimental malaria. Similar findings in other clinical situations and the relevant literature are reviewed

  18. Development of vaccines against Plasmodium falciparum malaria: taking lessons from naturally acquired protective immunity

    DEFF Research Database (Denmark)

    Hviid, Lars

    2007-01-01

    The acquisition of substantial anti-malarial protection in people naturally exposed to P. falciparum is often cited as evidence that malaria vaccines can be developed, but is rarely used to guide the development. We are pursuing the development of vaccines based on antigens and immune responses...

  19. Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Helegbe, Gideon K; Goka, Bamenla Q; Kurtzhals, Jørgen

    2007-01-01

    BACKGROUND: Severe anaemia (SA), intravascular haemolysis (IVH) and respiratory distress (RD) are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism lead...

  20. Anti-Plasmodium falciparum invasion ligand antibodies in a low malaria transmission region, Loreto, Peru

    DEFF Research Database (Denmark)

    Villasis, Elizabeth; Lopez-Perez, Mary; Torres, Katherine

    2012-01-01

    Background: Erythrocyte invasion by Plasmodium falciparum is a complex process that involves two families; Erythrocyte Binding-Like (EBL) and the Reticulocyte Binding-Like (PfRh) proteins. Antibodies that inhibit merozoite attachment and invasion are believed to be important in mediating naturall...

  1. High level of resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine in children in Tanzania

    DEFF Research Database (Denmark)

    Rønn, A M; Msangeni, H A; Mhina, J

    1996-01-01

    In many areas of tropical Africa affected by chloroquine-resistant Plasmodium falciparum, a combination of sulfadoxine and pyrimethamine (S-P) is used for alternative medication, especially in young children. In Magoda village in Muheza District, north-eastern Tanzania, 38 children 1-10 years...

  2. DNA methyltransferase homologue TRDMT1 in Plasmodium falciparum specifically methylates endogenous aspartic acid tRNA.

    Science.gov (United States)

    Govindaraju, Gayathri; Jabeena, C A; Sethumadhavan, Devadathan Valiyamangalath; Rajaram, Nivethika; Rajavelu, Arumugam

    2017-10-01

    In eukaryotes, cytosine methylation regulates diverse biological processes such as gene expression, development and maintenance of genomic integrity. However, cytosine methylation and its functions in pathogenic apicomplexan protozoans remain enigmatic. To address this, here we investigated the presence of cytosine methylation in the nucleic acids of the protozoan Plasmodium falciparum. Interestingly, P. falciparum has TRDMT1, a conserved homologue of DNA methyltransferase DNMT2. However, we found that TRDMT1 did not methylate DNA, in vitro. We demonstrate that TRDMT1 methylates cytosine in the endogenous aspartic acid tRNA of P. falciparum. Through RNA bisulfite sequencing, we mapped the position of 5-methyl cytosine in aspartic acid tRNA and found methylation only at C38 position. P. falciparum proteome has significantly higher aspartic acid content and a higher proportion of proteins with poly aspartic acid repeats than other apicomplexan pathogenic protozoans. Proteins with such repeats are functionally important, with significant roles in host-pathogen interactions. Therefore, TRDMT1 mediated C38 methylation of aspartic acid tRNA might play a critical role by translational regulation of important proteins and modulate the pathogenicity of the malarial parasite. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Genetic diversity of merozoite surface protein-2 in Plasmodium falciparum isolates from Aceh province, Indonesia

    Science.gov (United States)

    Jamil, K. F.; Supargiyono, S.; Syafruddin, D.; Pratama, N.; Silvy, S.

    2018-03-01

    Estimated 3.3 million Indonesian population were infected with malaria. However, extensive genetic polymorphism of the field isolates MSP-2 of P. falciparum represents a major obstacle for the development of malaria treatment. The aim of this study to investigate the genetic diversity of MSP-2 genotype in field isolates of P. falciparum collected in Aceh Province. A total of 90 patients enrolled in this study who were selected from positive malaria from eleven district Hospitals in Aceh from 2013-2015. Data was collected by anamnesis, complete physical examination and laboratory tests for MSP-2. All protocol to diagnose malaria assigned following the WHO 2010 guideline. All samples were stored in Eijkman Biology Molecular Institute, Jakarta.Among 90 samples were 57.7% male and 42.3% female with the most cases ages between 21-30 years old. Allele typing analysis displayed the polymorphic nature of P. falciparum. The MSP-2 have two alleles, 62.2% (56/90) for FC27 type and 58.9% (53/90) for 3D7 type and 21.2% (19/90) for mixed FC27 and 3D7 infection were identified. Diverse allele types from Aceh Province was identified in MSP-2 P. falciparum patients; there is the almost similar number of patients infected with both allele. A moderate level of the mixed allele was also observed.

  4. Recombinant Plasmodium falciparum glutamate rich protein; purification and use in enzyme-linked immunosorbent assay

    DEFF Research Database (Denmark)

    Dziegiel, Morten Hanefeld; Borre, M B; Jepsen, S

    1991-01-01

    New Guinea (MAD20) and Honduras (HB3) completely absorbed specific antibodies, indicating the presence of conserved epitopes produced by all isolates of P. falciparum. Recombinant GLURP489-1271 ELISA is sensitive and rapid, and therefore well-suited for sero-epidemiological studies, and for control...

  5. Genetic structure of Plasmodium falciparum populations across the Honduras-Nicaragua border.

    Science.gov (United States)

    Larrañaga, Nerea; Mejía, Rosa E; Hormaza, José I; Montoya, Alberto; Soto, Aida; Fontecha, Gustavo A

    2013-10-04

    The Caribbean coast of Central America remains an area of malaria transmission caused by Plasmodium falciparum despite the fact that morbidity has been reduced in recent years. Parasite populations in that region show interesting characteristics such as chloroquine susceptibility and low mortality rates. Genetic structure and diversity of P. falciparum populations in the Honduras-Nicaragua border were analysed in this study. Seven neutral microsatellite loci were analysed in 110 P. falciparum isolates from endemic areas of Honduras (n = 77) and Nicaragua (n = 33), mostly from the border region called the Moskitia. Several analyses concerning the genetic diversity, linkage disequilibrium, population structure, molecular variance, and haplotype clustering were conducted. There was a low level of genetic diversity in P. falciparum populations from Honduras and Nicaragua. Expected heterozigosity (H(e)) results were similarly low for both populations. A moderate differentiation was revealed by the F(ST) index between both populations, and two putative clusters were defined through a structure analysis. The main cluster grouped most of samples from Honduras and Nicaragua, while the second cluster was smaller and included all the samples from the Siuna community in Nicaragua. This result could partially explain the stronger linkage disequilibrium (LD) in the parasite population from that country. These findings are congruent with the decreasing rates of malaria endemicity in Central America.

  6. Identification of glycosaminoglycan binding regions in the Plasmodium falciparum encoded placental sequestration ligand, VAR2CSA

    DEFF Research Database (Denmark)

    Resende, Mafalda; Nielsen, Morten A.; Dahlbaeck, Madeleine

    2008-01-01

    Background: Pregnancy malaria is caused by Plasmodium falciparum-infected erythrocytes binding the placental receptor chondroitin sulfate A (CSA). This results in accumulation of parasites in the placenta with severe clinical consequences for the mother and her unborn child. Women become resistan...

  7. Molecular markers of antifolate resistance in Plasmodium falciparum isolates from Luanda, Angola

    Science.gov (United States)

    2011-01-01

    Background Plasmodium falciparum malaria remains a leading health problem in Africa and its control is seriously challenged by drug resistance. Although resistance to the sulphadoxine-pyrimethamine (SP) is widespread, this combination remains an important component of malaria control programmes as intermittent preventive therapy (IPT) for pregnant women and children. In Angola, resistance patterns have been poorly characterized, and IPT has been employed for pregnant women since 2006. The aim of this study was to assess the prevalence of key antifolate resistance mediating polymorphisms in the pfdhfr and pfdhps genes in P. falciparum samples from Angola. Methods Plasmodium falciparum samples collected in Luanda, in 2007, were genotyped by amplification and DNA forward and reverse sequencing of the pfdhfr and pfdhps genes. Results The most prevalent polymorphisms identified were pfdhfr 108N (100%), 51I (93%), 59R (57%) and pfdhps 437G (93%). Resistance-mediating polymorphisms in pfdhps less commonly observed in West Africa were also identified (540E in 10%, 581G in 7% of samples). Conclusion This study documents an important prevalence of 4 P. falciparum polymorphisms that predicts an antifolate resistance in Luanda. Further, some samples presented additional mutations associated to high-level resistance. These results suggest that the use of SP for IPT may no longer be warranted in Angola. PMID:21864379

  8. Profil Fenotipik Plasmodium falciparum Galur Papua 2300 Akibat Paparan Antimalaria Artemisinin in Vitro

    Directory of Open Access Journals (Sweden)

    Lilik Maslachah

    2015-03-01

    Full Text Available The presence of the P. falciparum resistance and decreased of efficacy against artemisinin and its derivatives result in increasingly complex malaria issues. Malaria has become one of the currently unresolved world’s health problems due to the lack of new artemisinin replacement drugs. This study aimed to provide evidence that the repeated exposure of in vitro artemisinin may cause a change in P. falciparum Papua 2300 strain phenotypic. This study was conducted during the period of February to November 2013 in Biomedics Brawijaya University and the Faculty of Veterinary Medicine, Airlangga University. A post-test control only experimental design was used. In vitro cultures of P. falciparum Papua 2300 strain were treated by repeated artemisin in IC50 concentration and were observed for their viability and IC50 using probit analysis. The control group did not show any changes after IC50value and PO1 treatment. An increase in IC50 value was occurred after PO2. Repeated exposures of artemisinin in PO2, PO3 and PO4 had shorter viability periods than PO1. The viability of was stable after PO3 in this group. In conclusion, repeated exposures of artemisinin influence changes in IC50 value and viability period of P. falciparum Papua 2300 strain.

  9. Filter paper collection of Plasmodium falciparum mRNA for detecting low-density gametocytes

    NARCIS (Netherlands)

    Jones, S.; Sutherland, C.J.; Hermsen, C.C.; Arens, T.; Teelen, K.A.E.M.; Hallett, R.; Corran, P.; van der Vegte-Bolmer, M.; Sauerwein, R.; Drakeley, C.; Bousema, J.T.

    2012-01-01

    ABSTRACT: BACKGROUND: Accurate sampling of sub-microscopic gametocytes is necessary for epidemiological studies to identify the infectious reservoir of Plasmodium falciparum. Detection of gametocyte mRNA achieves sensitive detection, but requires careful handling of samples. Filter papers can be

  10. Containment Of Outbreak Of P. Falciparum Malaria In Community Development Block Lakhanmajra

    Directory of Open Access Journals (Sweden)

    Lal Sunder

    1996-01-01

    Full Text Available Research question: What strategies need to be adopted to contain an outbreak of plasmodium falciparum in rural community. Objective: To improve active case detection and prompt fever mass treatment as also to ensure follow up activities. Study Design: Population based longitudinal study. Setting: Villages showing high Incidence of plasmodium falciparum malaria. Participant: All persons having fever or giving history of fever in the past 15 days. Outcome Variables: Recovered or cured, persistence of fever, death. Statistical analysis: Malariometric indices. Results: A rising trend of fever in block Lakhanmajra was obvious as ABER of 1995 was more than double (28.3 as compared to the year1991 (12.7. Similar API, SPR, AFI & SFR also increased significantly. Average slide positivity rate of the past three years was 8.1% and the slide positivity rate in the last three years increased by two and half time and plasmodium falciparum proportion was well above 33.5% and many deaths due to falciparum malaria were registered in some sections. Thus the area being high risk area, prone to epidemics. No evidence of drug resistance was observable. Pf Malaria deaths were averted, the explosive incidence was contained, improved and sustained surveillance operations helped early detection and prompt treatment of cases in their homes. People’s confidence and participation was ensured through DDCs & FTDs (Drug Distribution Centers and Fever Treatment Depots workers’ morale was raised through adequate support and guidance.

  11. Relative Susceptibilities of ABO Blood Groups to Plasmodium falciparum Malaria in Ghana

    Directory of Open Access Journals (Sweden)

    Richmond Afoakwah

    2016-01-01

    Full Text Available The clinical outcome of falciparum malaria in endemic areas is influenced by erythrocyte polymorphisms including the ABO blood groups. Studies have reported association of ABO blood group to resistance, susceptibility, and severity of P. falciparum malaria infection. Individuals with blood group “A” have been found to be highly susceptible to falciparum malaria whereas blood group “O” is said to confer protection against complicated cases. We analyzed samples from 293 young children less than six years old with malaria in the Korle-Bu Teaching Hospital in Accra, Ghana. It was observed that group O was present in about 16.1% of complicated cases weighed against 40.9% of uncomplicated controls. Individuals with complicated malaria were about twice likely to be of blood groups A and B compared to group O (A versus O, OR = 1.90, 95% CI = 1.59–2.26, P<0.0001; B versus O, OR = 1.82. 95% CI = 1.57–2.23, P<0.0001. Blood group O participants with complicated diseases had low parasitaemia compared to the other blood groups (P<0.0001. This may give blood group O individuals a survival advantage over the other groups in complicated malaria as suggested. Participants with complicated falciparum malaria were generally anaemic and younger than those with uncomplicated disease.

  12. Clinical and parasitological profiles of patients with non-complicated Plasmodium falciparum and Plasmodium vivax malaria in northwestern Colombia

    OpenAIRE

    Knudson-Ospina, Angélica; Sánchez-Pedraza, Ricardo; Pérez-Mazorra, Manuel Alberto; Cortés-Cortés, Liliana Jazmín; Guerra-Vega, Ángela Patricia; Nicholls-Orejuela, Rubén Santiago

    2015-01-01

    Antecedentes. En Colombia existen pocos estudios que buscan encontrar diferencias clínicas y parasitológicas en la malaria causada por Plasmodium falciparum y Plasmodium vivax. Objetivo. Describir el perfil clínico y parasitológico de las malarias por Plasmodium falciparum y Plasmodium vivax no complicadas en Tierralta, Córdoba, Colombia. Materiales y métodos. Se evaluaron pacientes con paludismo no complicado por Plasmodium falciparum y Plasmodium vivax según los protocolos estandarizados po...

  13. Aotus infulatus monkey is susceptible to Plasmodium falciparum infection and may constitute an alternative experimental model for malaria

    Directory of Open Access Journals (Sweden)

    Carvalho Leonardo JM

    2000-01-01

    Full Text Available Aotus is one of the WHO-recommended primate models for studies in malaria, and several species can be infected with Plasmodium falciparum or P. vivax. Here we describe the successful infection of the species A. infulatus from eastern Amazon with blood stages of P. falciparum. Both intact and splenectomized animals were susceptible to infection; the intact ones were able to keep parasitemias at lower levels for several days, but developed complications such as severe anemia; splenectomized monkeys developed higher parasitemias but no major complications. We conclude that A. infulatus is susceptible to P. falciparum infection and may represent an alternative model for studies in malaria.

  14. Proteomic analysis revealed alterations of the Plasmodium falciparum metabolism following salicylhydroxamic acid exposure

    Directory of Open Access Journals (Sweden)

    Torrentino-Madamet M

    2011-09-01

    Full Text Available Marylin Torrentino-Madamet1, Lionel Almeras2, Christelle Travaillé1, Véronique Sinou1, Matthieu Pophillat3, Maya Belghazi4, Patrick Fourquet3, Yves Jammes5, Daniel Parzy11UMR-MD3, Université de la Méditerranée, Antenne IRBA de Marseille (IMTSSA, Le Pharo, 2Unité de Recherche en Biologie et Epidémiologie Parasitaires, Antenne IRBA de Marseille (IMTSSA, Le Pharo, 3Centre d'Immunologie de Marseille Luminy, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée, 4Centre d'Analyse Protéomique de Marseille, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, 5UMR-MD2, Physiologie et Physiopathologie en Conditions d'Oxygénations Extrêmes, Institut Fédératif de Recherche Jean Roche, Faculté de Médecine Nord, Marseille, FranceObjectives: Although human respiratory metabolism is characterized by the mitochondrial electron transport chain, some organisms present a “branched respiratory chain.” This branched pathway includes both a classical and an alternative respiratory chain. The latter involves an alternative oxidase. Though the Plasmodium falciparum alternative oxidase is not yet identified, a specific inhibitor of this enzyme, salicylhydroxamic acid (SHAM, showed a drug effect on P. falciparum respiratory function using oxygen consumption measurements. The present study aimed to highlight the metabolic pathways that are affected in P. falciparum following SHAM exposure.Design: A proteomic approach was used to analyze the P. falciparum proteome and determine the metabolic pathways altered following SHAM treatment. To evaluate the SHAM effect on parasite growth, the phenotypic alterations of P. falciparum after SHAM or/and hyperoxia exposure were observed.Results: After SHAM exposure, 26 proteins were significantly deregulated using a fluorescent two dimensional-differential gel electrophoresis. Among these deregulated proteins

  15. Functional analysis of a missense mutation in the serine protease inhibitor SPINT2 associated with congenital sodium diarrhea.

    Directory of Open Access Journals (Sweden)

    Nicolas Faller

    Full Text Available Membrane-bound serine proteases play important roles in different biological processes. Their regulation by endogenous inhibitors is poorly understood. A Y163C mutation in the SPINT2 gene encoding the serine protease inhibitor Hepatocyte Growth Factor Inhibitor HAI-2 is associated with a congenital sodium diarrhea. The functional consequences of this mutation on HAI-2 activity and its physiological targets are unknown. We established a cellular assay in Xenopus laevis oocytes to study functional interactions between HAI-2 and candidate membrane-bound serine proteases expressed in the gastro-intestinal tract. We found that the wild-type form of HAI-2 is a potent inhibitor of nine gastro-intestinal serine proteases. The Y163C mutation in the second Kunitz domain of HAI-2 resulted in a complete loss of inhibitory activity on two intestinal proteases, prostasin and tmprss13. The effect of the mutation of the homologous Y68C in the first Kunitz domain of HAI-2 is consistent with a differential contribution of the two Kunitz domains of HAI-2 in the inhibition of serine proteases. By contrast to the Tyr to Cys, the Tyr to Ser substitution did not change the inhibitory potency of HAI-2, indicating that the thiol-group of the cysteine rather than the Tyr deletion is responsible for the HAI-2 loss of function. Our functional assay allowed us to identify membrane-bound serine proteases as cellular target for inhibition by HAI-2 wild type and mutants, and to better define the role of the Tyr in the second Kunitz domain in the inhibitory activity of HAI-2.

  16. Specific membrane binding of factor VIII is mediated by O-phospho-L-serine, a moiety of phosphatidylserine.

    Science.gov (United States)

    Gilbert, G E; Drinkwater, D

    1993-09-21

    Phosphatidylserine, a negatively charged lipid, is exposed on the platelet membrane following cell stimulation, correlating with the expression of factor VIII receptors. We have explored the importance of the negative electrostatic potential of phosphatidylserine vs chemical moieties of phosphatidylserine for specific membrane binding of factor VIII. Fluorescein-labeled factor VIII bound to membranes containing 15% phosphatidic acid, a negatively charged phospholipid, with low affinity compared to phosphatidylserine-containing membranes. Binding was not specific as it was inhibited by other proteins in plasma. Factor VIII bound to membranes containing 10% phosphatidylserine in spite of a varying net charge provided by 0-15% stearylamine, a positively charged lipid. The soluble phosphatidylserine moiety, O-phospho-L-serine, inhibited factor VIII binding to phosphatidylserine-containing membranes with a Ki of 20 mM, but the stereoisomer, O-phospho-D-serine, was 5-fold less effective. Furthermore, binding of factor VIII to membranes containing synthetic phosphatidyl-D-serine was 5-fold less than binding to membranes containing phosphatidyl-L-serine. Membranes containing synthetic phosphatidyl-L-homoserine, differing from phosphatidylserine by a single methylene, supported high-affinity binding, but it was not specific as factor VIII was displaced by other plasma proteins. O-Phospho-L-serine also inhibited the binding of factor VIII to platelet-derived microparticles with a Ki of 20 mM, and the stereoisomer was 4-fold less effective. These results indicate that membrane binding of factor VIII is mediated by a stereoselective recognition O-phospho-L-serine of phosphatidylserine and that negative electrostatic potential is of lesser importance.

  17. Anti-fibrinolytic and anti-microbial activities of a serine protease inhibitor from honeybee (Apis cerana) venom.

    Science.gov (United States)

    Yang, Jie; Lee, Kwang Sik; Kim, Bo Yeon; Choi, Yong Soo; Yoon, Hyung Joo; Jia, Jingming; Jin, Byung Rae

    2017-10-01

    Bee venom contains a variety of peptide constituents, including low-molecular-weight protease inhibitors. While the putative low-molecular-weight serine protease inhibitor Api m 6 containing a trypsin inhibitor-like cysteine-rich domain was identified from honeybee (Apis mellifera) venom, no anti-fibrinolytic or anti-microbial roles for this inhibitor have been elucidated. In this study, we identified an Asiatic honeybee (A. cerana) venom serine protease inhibitor (AcVSPI) that was shown to act as a microbial serine protease inhibitor and plasmin inhibitor. AcVSPI was found to consist of a trypsin inhibitor-like domain that displays ten cysteine residues. Interestingly, the AcVSPI peptide sequence exhibited high similarity to the putative low-molecular-weight serine protease inhibitor Api m 6, which suggests that AcVSPI is an allergen Api m 6-like peptide. Recombinant AcVSPI was expressed in baculovirus-infected insect cells, and it demonstrated inhibitory activity against trypsin, but not chymotrypsin. Additionally, AcVSPI has inhibitory effects against plasmin and microbial serine proteases; however, it does not have any detectable inhibitory effects on thrombin or elastase. Consistent with these inhibitory effects, AcVSPI inhibited the plasmin-mediated degradation of fibrin to fibrin degradation products. AcVSPI also bound to bacterial and fungal surfaces and exhibited anti-microbial activity against fungi as well as gram-positive and gram-negative bacteria. These findings demonstrate the anti-fibrinolytic and anti-microbial roles of AcVSPI as a serine protease inhibitor. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Negative Role of RIG-I Serine 8 Phosphorylation in the Regulatin of Interferon-beta Production

    Energy Technology Data Exchange (ETDEWEB)

    E Nistal-Villan; M Gack; G Martinez-Delgado; N Maharaj; K Inn; H Yang; R Wang; A Aggarwal; J Jung; A Garcia-Sastre

    2011-12-31

    RIG-I (retinoic acid-inducible gene I) and TRIM25 (tripartite motif protein 25) have emerged as key regulatory factors to induce interferon (IFN)-mediated innate immune responses to limit viral replication. Upon recognition of viral RNA, TRIM25 E3 ligase binds the first caspase recruitment domain (CARD) of RIG-I and subsequently induces lysine 172 ubiquitination of the second CARD of RIG-I, which is essential for the interaction with downstream MAVS/IPS-1/CARDIF/VISA and, thereby, IFN-beta mRNA production. Although ubiquitination has emerged as a major factor involved in RIG-I activation, the potential contribution of other post-translational modifications, such as phosphorylation, to the regulation of RIG-I activity has not been addressed. Here, we report the identification of serine 8 phosphorylation at the first CARD of RIG-I as a negative regulatory mechanism of RIG-I-mediated IFN-beta production. Immunoblot analysis with a phosphospecific antibody showed that RIG-I serine 8 phosphorylation steady-state levels were decreased upon stimulation of cells with IFN-beta or virus infection. Substitution of serine 8 in the CARD RIG-I functional domain with phosphomimetic aspartate or glutamate results in decreased TRIM25 binding, RIG-I ubiquitination, MAVS binding, and downstream signaling. Finally, sequence comparison reveals that only primate species carry serine 8, whereas other animal species carry an asparagine, indicating that serine 8 phosphorylation may represent a primate-specific regulation of RIG-I activation. Collectively, these data suggest that the phosphorylation of RIG-I serine 8 operates as a negative switch of RIG-I activation by suppressing TRIM25 interaction, further underscoring the importance of RIG-I and TRIM25 connection in type I IFN signal transduction.

  19. A systematic classification of Plasmodium falciparum P-loop NTPases: structural and functional correlation

    Directory of Open Access Journals (Sweden)

    Chauhan Virander S

    2009-04-01

    Full Text Available Abstract Background The P-loop NTPases constitute one of the largest groups of globular protein domains that play highly diverse functional roles in most of the organisms. Even with the availability of nearly 300 different Hidden Markov Models representing the P-loop NTPase superfamily, not many P-loop NTPases are known in Plasmodium falciparum. A number of characteristic attributes of the genome have resulted into the lack of knowledge about this functionally diverse, but important class of proteins. Method In the study, protein sequences with characteristic motifs of NTPase domain (Walker A and Walker B are computationally extracted from the P. falciparum database. A detailed secondary structure analysis, functional classification, phylogenetic and orthology studies of the NTPase domain of repertoire of 97 P. falciparum P-loop NTPases is carried out. Results Based upon distinct sequence features and secondary structure profile of the P-loop domain of obtained sequences, a cladistic classification is also conceded: nucleotide kinases and GTPases, ABC and SMC family, SF1/2 helicases, AAA+ and AAA protein families. Attempts are made to identify any ortholog(s for each of these proteins in other Plasmodium sp. as well as its vertebrate host, Homo sapiens. A number of P. falciparum P-loop NTPases that have no homologue in the host, as well as those annotated as hypothetical proteins and lack any characteristic functional domain are identified. Conclusion The study suggests a strong correlation between sequence and secondary structure profile of P-loop domains and functional roles of these proteins and thus provides an opportunity to speculate the role of many hypothetical proteins. The study provides a methodical framework for the characterization of biologically diverse NTPases in the P. falciparum genome. The efforts made in the analysis are first of its kind; and the results augment to explore the functional role of many of these proteins from

  20. Mitotic evolution of Plasmodium falciparum shows a stable core genome but recombination in antigen families.

    Directory of Open Access Journals (Sweden)

    Selina E R Bopp

    Full Text Available Malaria parasites elude eradication attempts both within the human host and across nations. At the individual level, parasites evade the host immune responses through antigenic variation. At the global level, parasites escape drug pressure through single nucleotide variants and gene copy amplification events conferring drug resistance. Despite their importance to global health, the rates at which these genomic alterations emerge have not been determined. We studied the complete genomes of different Plasmodium falciparum clones that had been propagated asexually over one year in the presence and absence of drug pressure. A combination of whole-genome microarray analysis and next-generation deep resequencing (totaling 14 terabases revealed a stable core genome with only 38 novel single nucleotide variants appearing in seventeen evolved clones (avg. 5.4 per clone. In clones exposed to atovaquone, we found cytochrome b mutations as well as an amplification event encompassing the P. falciparum multidrug resistance associated protein (mrp1 on chromosome 1. We observed 18 large-scale (>1 kb on average deletions of telomere-proximal regions encoding multigene families, involved in immune evasion (9.5×10(-6 structural variants per base pair per generation. Six of these deletions were associated with chromosomal crossovers generated during mitosis. We found only minor differences in rates between genetically distinct strains and between parasites cultured in the presence or absence of drug. Using these derived mutation rates for P. falciparum (1.0-9.7×10(-9 mutations per base pair per generation, we can now model the frequency at which drug or immune resistance alleles will emerge under a well-defined set of assumptions. Further, the detection of mitotic recombination events in var gene families illustrates how multigene families can arise and change over time in P. falciparum. These results will help improve our understanding of how P. falciparum

  1. Modelling the incidence of Plasmodium vivax and Plasmodium falciparum malaria in Afghanistan 2006-2009.

    Science.gov (United States)

    Alegana, Victor A; Wright, Jim A; Nahzat, Sami M; Butt, Waqar; Sediqi, Amad W; Habib, Naeem; Snow, Robert W; Atkinson, Peter M; Noor, Abdisalan M

    2014-01-01

    Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. From the analysis of healthcare utilisation, over 80% of the population was within 2 hours' travel of the nearest public health facility, while 64.4% were within 30 minutes' travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2-9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4-2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan.

  2. Modelling the Incidence of Plasmodium vivax and Plasmodium falciparum Malaria in Afghanistan 2006–2009

    Science.gov (United States)

    Alegana, Victor A.; Wright, Jim A.; Nahzat, Sami M.; Butt, Waqar; Sediqi, Amad W.; Habib, Naeem; Snow, Robert W.; Atkinson, Peter M.; Noor, Abdisalan M.

    2014-01-01

    Background Identifying areas that support high malaria risks and where populations lack access to health care is central to reducing the burden in Afghanistan. This study investigated the incidence of Plasmodium vivax and Plasmodium falciparum using routine data to help focus malaria interventions. Methods To estimate incidence, the study modelled utilisation of the public health sector using fever treatment data from the 2012 national Malaria Indicator Survey. A probabilistic measure of attendance was applied to population density metrics to define the proportion of the population within catchment of a public health facility. Malaria data were used in a Bayesian spatio-temporal conditional-autoregressive model with ecological or environmental covariates, to examine the spatial and temporal variation of incidence. Findings From the analysis of healthcare utilisation, over 80% of the population was within 2 hours’ travel of the nearest public health facility, while 64.4% were within 30 minutes’ travel. The mean incidence of P. vivax in 2009 was 5.4 (95% Crl 3.2–9.2) cases per 1000 population compared to 1.2 (95% Crl 0.4–2.9) cases per 1000 population for P. falciparum. P. vivax peaked in August while P. falciparum peaked in November. 32% of the estimated 30.5 million people lived in regions where annual incidence was at least 1 case per 1,000 population of P. vivax; 23.7% of the population lived in areas where annual P. falciparum case incidence was at least 1 per 1000. Conclusion This study showed how routine data can be combined with household survey data to model malaria incidence. The incidence of both P. vivax and P. falciparum in Afghanistan remain low but the co-distribution of both parasites and the lag in their peak season provides challenges to malaria control in Afghanistan. Future improved case definition to determine levels of imported risks may be useful for the elimination ambitions in Afghanistan. PMID:25033452

  3. Infants' Peripheral Blood Lymphocyte Composition Reflects Both Maternal and Post-Natal Infection with Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Odilon Nouatin

    Full Text Available Maternal parasitoses modulate fetal immune development, manifesting as altered cellular immunological activity in cord blood that may be linked to enhanced susceptibility to infections in early life. Plasmodium falciparum typifies such infections, with distinct placental infection-related changes in cord blood exemplified by expanded populations of parasite antigen-specific regulatory T cells. Here we addressed whether such early-onset cellular immunological alterations persist through infancy. Specifically, in order to assess the potential impacts of P. falciparum infections either during pregnancy or during infancy, we quantified lymphocyte subsets in cord blood and in infants' peripheral blood during the first year of life. The principal age-related changes observed, independent of infection status, concerned decreases in the frequencies of CD4+, NKdim and NKT cells, whilst CD8+, Treg and Teff cells' frequencies increased from birth to 12 months of age. P. falciparum infections present at delivery, but not those earlier in gestation, were associated with increased frequencies of Treg and CD8+ T cells but fewer CD4+ and NKT cells during infancy, thus accentuating the observed age-related patterns. Overall, P. falciparum infections arising during infancy were associated with a reversal of the trends associated with maternal infection i.e. with more CD4+ cells, with fewer Treg and CD8+ cells. We conclude that maternal P. falciparum infection at delivery has significant and, in some cases, year-long effects on the composition of infants' peripheral blood lymphocyte populations. Those effects are superimposed on separate and independent age- as well as infant infection-related alterations that, respectively, either match or run counter to them.

  4. Plasmodium falciparum: genetic diversity and complexity of infections in an isolated village in western Thailand.

    Science.gov (United States)

    Tanabe, Kazuyuki; Zollner, Gabriela; Vaughan, Jefferson A; Sattabongkot, Jetsumon; Khuntirat, Benjawan; Honma, Hajime; Mita, Toshihiro; Tsuboi, Takafumi; Coleman, Russell

    2015-06-01

    Genetic diversity of Plasmodium falciparum is intimately associated with morbidity, mortality and malaria control strategies. It is therefore imperative to study genetic makeup and population structure of this parasite in endemic areas. In Kong Mong Tha, an isolated village in western Thailand, the majority of P. falciparum infections are asymptomatic. In this study we investigated complexity of infections and single nucleotide polymorphisms (SNPs) in the P. falciparum population of Kong Mong Tha, and compared results with those previously obtained from Mae Sod, in northwestern Thailand, where the majority of infections were symptomatic. Using PCR-based determination of the 5' merozoite surface protein 1 gene (msp1) recombinant types, we found that 39% of 59 P. falciparum isolates from Kong Mong Tha had multiple 5' recombinant types with a mean number of 1.54. These values were much lower than those obtained from Mae Sod: 96% for multiple infections and with a mean number of 3.61. Analysis of full-length sequences of two housekeeping genes, the P-type Ca(2+)-transporting ATPase gene (n=33) plus adenylosuccinate lyase gene (n=33), and three vaccine candidate antigen genes, msp1 (n=26), the circumsporozoite protein gene, csp (n=30) and the apical membrane antigen 1 gene, ama 1 (n=32), revealed that in all of these genes within-population SNP diversity was at similar levels between Kong Mong Tha and Mae Sod, suggesting that the extent of MOI and clinical manifestations of malaria are not strongly associated with genetic diversity. Additionally, we did not detect significant genetic differentiation between the two parasite populations, as estimated by the Wright's fixation index of inter-population variance in allele frequencies, suggesting that gene flow prevented the formation of population structuring. Thus, this study highlights unique features of P. falciparum populations in Thailand. The implications of these finding are discussed. © 2013.

  5. International funding for malaria control in relation to populations at risk of stable Plasmodium falciparum transmission.

    Directory of Open Access Journals (Sweden)

    Robert W Snow

    2008-07-01

    Full Text Available The international financing of malaria control has increased significantly in the last ten years in parallel with calls to halve the malaria burden by the year 2015. The allocation of funds to countries should reflect the size of the populations at risk of infection, disease, and death. To examine this relationship, we compare an audit of international commitments with an objective assessment of national need: the population at risk of stable Plasmodium falciparum malaria transmission in 2007.The national distributions of populations at risk of stable P. falciparum transmission were projected to the year 2007 for each of 87 P. falciparum-endemic countries. Systematic online- and literature-based searches were conducted to audit the international funding commitments made for malaria control by major donors between 2002 and 2007. These figures were used to generate annual malaria funding allocation (in US dollars per capita population at risk of stable P. falciparum in 2007. Almost US$1 billion are distributed each year to the 1.4 billion people exposed to stable P. falciparum malaria risk. This is less than US$1 per person at risk per year. Forty percent of this total comes from the Global Fund to Fight AIDS, Tuberculosis and Malaria. Substantial regional and national variations in disbursements exist. While the distribution of funds is found to be broadly appropriate, specific high population density countries receive disproportionately less support to scale up malaria control. Additionally, an inadequacy of current financial commitments by the international community was found: under-funding could be from 50% to 450%, depending on which global assessment of the cost required to scale up malaria control is adopted.Without further increases in funding and appropriate targeting of global malaria control investment it is unlikely that international goals to halve disease burdens by 2015 will be achieved. Moreover, the additional financing

  6. Prevalence of Dihydrofolate reductase gene mutations in Plasmodium falciparum isolate from pregnant women in Nigeria

    Directory of Open Access Journals (Sweden)

    Olusola Ojurongbe

    2011-12-01

    Full Text Available We assessed the prevalence of Plasmodium falciparum and the frequency of the dhfr triple mutation that is associated with antifolate drug resistance among P. falciparumisolates obtained from pregnant women in Ilorin, Nigeria. The study included 179 women in the second and third trimester of pregnancy who have been exposed to intermittent preventive treatment in pregnancy (IPTp with sulfadoxinepyrimethamine. Thick and thin blood films and PCR were used for malaria parasite detection. Blood group and hemoglobin concentration were also determined. Mutations in P. falciparum dhfr were analyzed by sequencing DNA obtained from blood spots on filter paper. Prevalence of P. falciparum in the population (PCR corrected was 44.1% (79/179 with 66.7% and 33.3% in the second and third trimester, respectively. Primigravide (51.3% were more infected than multigravide (48.7% but the difference was not statistically significant. Women in blood group A had the highest P. falciparum malaria infection (30.8%. The mean hemoglobin concentration was lower among those infected with malaria parasite. Also, more women with the malaria parasite (38.4% had anemia compare to those without (21.4%. The prevalence of the P. falciparum dhfr mutant alleles was 64.1%, 61.5%, 38.5%, and 12.8% for I51, R59, N108 and T108, respectively. None of the samples had the L164 mutation. The combined triple dhfr mutation (51 + 59 + 108 in the population was 17.9% (7 of 39. Also, the prevalence of the triple mutant alleles was not significantly associated to the number of doses of SP taken by the women. These findings highlight the need for a regular assessment of IPTp/SP efficacy, and evaluation of possible alternative drugs.

  7. Putative DNA G-quadruplex formation within the promoters of Plasmodium falciparum var genes

    Directory of Open Access Journals (Sweden)

    Rowe J

    2009-08-01

    Full Text Available Abstract Background Guanine-rich nucleic acid sequences are capable of folding into an intramolecular four-stranded structure called a G-quadruplex. When found in gene promoter regions, G-quadruplexes can downregulate gene expression, possibly by blocking the transcriptional machinery. Here we have used a genome-wide bioinformatic approach to identify Putative G-Quadruplex Sequences (PQS in the Plasmodium falciparum genome, along with biophysical techniques to examine the physiological stability of P. falciparum PQS in vitro. Results We identified 63 PQS in the non-telomeric regions of the P. falciparum clone 3D7. Interestingly, 16 of these PQS occurred in the upstream region of a subset of the P. falciparum var genes (group B var genes. The var gene family encodes PfEMP1, the parasite's major variant antigen and adhesin expressed at the surface of infected erythrocytes, that plays a key role in malaria pathogenesis and immune evasion. The ability of the PQS found in the upstream regions of group B var genes (UpsB-Q to form stable G-quadruplex structures in vitro was confirmed using 1H NMR, circular dichroism, UV spectroscopy, and thermal denaturation experiments. Moreover, the synthetic compound BOQ1 that shows a higher affinity for DNA forming quadruplex rather than duplex structures was found to bind with high affinity to the UpsB-Q. Conclusion This is the first demonstration of non-telomeric PQS in the genome of P. falciparum that form stable G-quadruplexes under physiological conditions in vitro. These results allow the generation of a novel hypothesis that the G-quadruplex sequences in the upstream regions of var genes have the potential to play a role in the transcriptional control of this major virulence-associated multi-gene family.

  8. Cytokine balance in human malaria: does Plasmodium vivax elicit more inflammatory responses than Plasmodium falciparum?

    Directory of Open Access Journals (Sweden)

    Raquel M Gonçalves

    Full Text Available BACKGROUND: The mechanisms by which humans regulate pro- and anti-inflammatory responses on exposure to different malaria parasites remains unclear. Although Plasmodium vivax usually causes a relatively benign disease, this parasite has been suggested to elicit more host inflammation per parasitized red blood cell than P. falciparum. METHODOLOGY/PRINCIPAL FINDINGS: We measured plasma concentrations of seven cytokines and two soluble tumor necrosis factor (TNF-α receptors, and evaluated clinical and laboratory outcomes, in Brazilians with acute uncomplicated infections with P. vivax (n = 85, P. falciparum (n = 30, or both species (n = 12, and in 45 asymptomatic carriers of low-density P. vivax infection. Symptomatic vivax malaria patients, compared to those infected with P. falciparum or both species, had more intense paroxysms, but they had no clear association with a pro-inflammatory imbalance. To the contrary, these patients had higher levels of the regulatory cytokine interleukin (IL-10, which correlated positively with parasite density, and elevated IL-10/TNF-α, IL-10/interferon (IFN-γ, IL-10/IL-6 and sTNFRII/TNF-α ratios, compared to falciparum or mixed-species malaria patient groups. Vivax malaria patients had the highest levels of circulating soluble TNF-α receptor sTNFRII. Levels of regulatory cytokines returned to normal values 28 days after P. vivax clearance following chemotherapy. Finally, asymptomatic carriers of low P. vivax parasitemias had substantially lower levels of both inflammatory and regulatory cytokines than did patients with clinical malaria due to either species. CONCLUSIONS: Controlling fast-multiplying P. falciparum blood stages requires a strong inflammatory response to prevent fulminant infections, while reducing inflammation-related tissue damage with early regulatory cytokine responses may be a more cost-effective strategy in infections with the less virulent P. vivax parasite. The early induction

  9. Mitotic Evolution of Plasmodium falciparum Shows a Stable Core Genome but Recombination in Antigen Families

    Science.gov (United States)

    Bopp, Selina E. R.; Manary, Micah J.; Bright, A. Taylor; Johnston, Geoffrey L.; Dharia, Neekesh V.; Luna, Fabio L.; McCormack, Susan; Plouffe, David; McNamara, Case W.; Walker, John R.; Fidock, David A.; Denchi, Eros Lazzerini; Winzeler, Elizabeth A.

    2013-01-01

    Malaria parasites elude eradication attempts both within the human host and across nations. At the individual level, parasites evade the host immune responses through antigenic variation. At the global level, parasites escape drug pressure through single nucleotide variants and gene copy amplification events conferring drug resistance. Despite their importance to global health, the rates at which these genomic alterations emerge have not been determined. We studied the complete genomes of different Plasmodium falciparum clones that had been propagated asexually over one year in the presence and absence of drug pressure. A combination of whole-genome microarray analysis and next-generation deep resequencing (totaling 14 terabases) revealed a stable core genome with only 38 novel single nucleotide variants appearing in seventeen evolved clones (avg. 5.4 per clone). In clones exposed to atovaquone, we found cytochrome b mutations as well as an amplification event encompassing the P. falciparum multidrug resistance associated protein (mrp1) on chromosome 1. We observed 18 large-scale (>1 kb on average) deletions of telomere-proximal regions encoding multigene families, involved in immune evasion (9.5×10−6 structural variants per base pair per generation). Six of these deletions were associated with chromosomal crossovers generated during mitosis. We found only minor differences in rates between genetically distinct strains and between parasites cultured in the presence or absence of drug. Using these derived mutation rates for P. falciparum (1.0–9.7×10−9 mutations per base pair per generation), we can now model the frequency at which drug or immune resistance alleles will emerge under a well-defined set of assumptions. Further, the detection of mitotic recombination events in var gene families illustrates how multigene families can arise and change over time in P. falciparum. These results will help improve our understanding of how P. falciparum evolves to

  10. Serine protease inhibitors containing a Kunitz domain: their role in modulation of host inflammatory responses and parasite survival.

    Science.gov (United States)

    de Magalhães, Mariana T Q; Mambelli, Fábio S; Santos, Bruno P O; Morais, Suellen B; Oliveira, Sergio C

    2018-03-31

    Proteins containing a Kunitz domain have the typical serine protease inhibition function ranging from sea anemone to man. Protease inhibitors play major roles in infection, inflammation disorders and cancer. This review discusses the role of serine proteases containing a Kunitz domain in immunomodulation induced by helminth parasites. Helminth parasites are associated with protection from inflammatory conditions. Therefore, interest has raised whether worm parasites or their products hold potential as drugs for treatment of immunological disorders. Finally, we also propose the use of recombinant SmKI-1 from Schistosoma mansoni as a potential therapeutic molecule to treat inflammatory diseases. Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  11. Analysis of L-serine-O-phosphate in cerebrospinal spinal fluid by derivatization-liquid chromatography/mass spectrometry.

    Science.gov (United States)

    McNaney, Colleen A; Benitex, Yulia; Luchetti, David; Labasi, Jeffrey M; Olah, Timothy V; Morgan, Daniel G; Drexler, Dieter M

    2014-05-01

    L-serine-O-phosphate (L-SOP), the precursor of L-serine, is a potent agonist against the group III metabotropic glutamate receptors (mGluRs) and, thus, is of interest as a potential biomarker for monitoring modulation of neurotransmitter release. So far, no reports are available on the analysis of L-SOP in cerebrospinal fluid (CSF). Here a novel method is presented to determine L-SOP levels in CSF employing precolumn derivatization with (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP) coupled to liquid chromatography/mass spectrometry (derivatization-LC/MS, d-LC/MS). Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Snake venom serine proteinases specificity mapping by proteomic identification of cleavage sites.

    Science.gov (United States)

    Zelanis, André; Huesgen, Pitter F; Oliveira, Ana Karina; Tashima, Alexandre K; Serrano, Solange M T; Overall, Christopher M

    2015-01-15

    Many snake venom toxins are serine proteases but their specific in vivo targets are mostly unknown. Various act on components of the coagulation cascade, and fibrinolytic and kallikrein-kinin systems to trigger various pathological effects observed in the envenomation. Despite showing high similarity in terms of primary structure snake venom serine proteinases (SVSPs) show exquisite specificity towards macromolecular substrates. Therefore, the characterization of their peptide bond specificity is important for understanding the active site preference associated with effective proteolysis as well as for the design of peptide substrates and inhibitors. Bothrops jararaca contains various SVSPs among which Bothrops protease A is a specific fibrinogenolytic agent and PA-BJ is a platelet-activating enzyme. In this study we used proteome derived peptide libraries in the Proteomic Identification of protease Cleavage Sites (PICS) approach to explore the peptide bond specificity of Bothrops protease A and PA-BJ in order to determine their individual peptide cleavage sequences. A total of 371 cleavage sites (208 for Bothrops protease A and 163 for PA-BJ) were detected and both proteinases displayed a clear preference for arginine at the P1 position. Moreover, the analysis of the specificity profiles of Bothrops protease A and PA-BJ revealed subtle differences in the preferences along P6-P6', despite a common yet unusual preference for Pro at P2. Taken together, these results map the subsite specificity of both SVSPs and shed light in the functional differences between these proteinases. Proteolysis is key to various pathological effects observed upon envenomation by viperid snakes. The use of the Proteomic Identification of protease Cleavage Sites (PICS) approach for the easy mapping of proteinase subsite preferences at both the prime- and non-prime sides concurrently gives rise to a fresh understanding of the interaction of the snake venom serine proteinases with peptide and

  13. Dihydrofolate reductase and dihydropteroate synthase genotypes associated with in vitro resistance of Plasmodium falciparum to pyrimethamine, trimethoprim, sulfadoxine, and sulfamethoxazole

    DEFF Research Database (Denmark)

    Khalil, Insaf; Rønn, Anita M; Alifrangis, Michael

    2003-01-01

    A total of 70 Plasmodium falciparum isolates were tested in vitro against pyrimethamine (PYR), trimethoprim (TRM), sulfadoxine (SDX), and sulfamethoxazole (SMX), and their dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genotypes were determined. dhfr genotypes correlated...

  14. Molecular and pharmacological determinants of the therapeutic response to artemether-lumefantrine in multidrug-resistant Plasmodium falciparum malaria

    NARCIS (Netherlands)

    Price, Ric N.; Uhlemann, Anne-Catrin; van Vugt, Michele; Brockman, Al; Hutagalung, Robert; Nair, Shalini; Nash, Denae; Singhasivanon, Pratap; Anderson, Tim J. C.; Krishna, Sanjeev; White, Nicholas J.; Nosten, François

    2006-01-01

    Our study examined the relative contributions of host, pharmacokinetic, and parasitological factors in determining the therapeutic response to artemether-lumefantrine (AL). On the northwest border of Thailand, patients with uncomplicated Plasmodium falciparum malaria were enrolled in prospective

  15. A switch in infected erythrocyte deformability at the maturation and blood circulation of Plasmodium falciparum transmission stages.

    NARCIS (Netherlands)

    Tiburcio, M.; Niang, M.; Deplaine, G.; Perrot, S.; Bischoff, E.; Ndour, P.A.; Silvestrini, F.; Khattab, A.; Milon, G.; David, P.H.; Hardeman, M.; Vernick, K.D.; Sauerwein, R.W.; Preiser, P.R.; Mercereau-Puijalon, O.; Buffet, P.; Alano, P.; Lavazec, C.

    2012-01-01

    Achievement of malaria elimination requires development of novel strategies interfering with parasite transmission, including targeting the parasite sexual stages (gametocytes). The formation of Plasmodium falciparum gametocytes in the human host takes several days during which immature

  16. A switch in infected erythrocyte deformability at the maturation and blood circulation of Plasmodium falciparum transmission stages

    NARCIS (Netherlands)

    Tibúrcio, Marta; Niang, Makhtar; Deplaine, Guillaume; Perrot, Sylvie; Bischoff, Emmanuel; Ndour, Papa Alioune; Silvestrini, Francesco; Khattab, Ayman; Milon, Geneviève; David, Peter H.; Hardeman, Max; Vernick, Kenneth D.; Sauerwein, Robert W.; Preiser, Peter R.; Mercereau-Puijalon, Odile; Buffet, Pierre; Alano, Pietro; Lavazec, Catherine

    2012-01-01

    Achievement of malaria elimination requires development of novel strategies interfering with parasite transmission, including targeting the parasite sexual stages (gametocytes). The formation of Plasmodium falciparum gametocytes in the human host takes several days during which immature

  17. Structural analysis of Staphylococcus aureus serine/threonine kinase PknB.

    Directory of Open Access Journals (Sweden)

    Sonja Rakette

    Full Text Available Effective treatment of infections caused by the bacterium Staphylococcus aureus remains a worldwide challenge, in part due to the constant emergence of new strains that are resistant to antibiotics. The serine/threonine kinase PknB is of particular relevance to the life cycle of S. aureus as it is involved in the regulation of purine biosynthesis, autolysis, and other central metabolic processes of the bacterium. We have determined the crystal structure of the kinase domain of PknB in complex with a non-hydrolyzable analog of the substrate ATP at 3.0 Å resolution. Although the purified PknB kinase is active in solution, it crystallized in an inactive, autoinhibited state. Comparison with other bacterial kinases provides insights into the determinants of catalysis, interactions of PknB with ligands, and the pathway of activation.

  18. IRS-1 serine phosphorylation and insulin resistance in skeletal muscle from pancreas tranplant recipient

    DEFF Research Database (Denmark)

    Bouzakri, K; Karlsson, HRK; Vestergaard, Henrik

    2006-01-01

    Insulin-dependent diabetic recipients of successful pancreas allografts achieve self-regulatory insulin secretion and discontinue exogenous insulin therapy; however, chronic hyperinsulinemia and impaired insulin sensitivity generally develop. To determine whether insulin resistance is accompanied....... In conclusion, peripheral insulin resistance in pancreas-kidney transplant recipients may arise from a negative feedback regulation of the canonical insulin-signaling cascade from excessive serine phosphorylation of IRS-1, possibly as a consequence of immunosuppressive therapy and hyperinsulinemia....... insulin receptor substrate (IRS)-1 Ser (312) and Ser (616) phosphorylation, IRS-1-associated phosphatidylinositol 3-kinase activity, and extracellular signal-regulated kinase (ERK)-1/2 phosphorylation were elevated in pancreas-kidney transplant recipients, coincident with fasting hyperinsulinemia. Basal...

  19. Distribution of serine/threonine kinase SAD-B in mouse peripheral nerve synapse.

    Science.gov (United States)

    Hagiwara, Akari; Harada, Kenu; Hida, Yamato; Kitajima, Isao; Ohtsuka, Toshihisa

    2011-05-11

    The serine/threonine kinase SAD regulates neural functions such as axon/dendrite polarization and neurotransmitter release. In the vertebrate central nervous system, SAD-B, a homolog of Caenorhabditis elegans SAD-1, is associated with synaptic vesicles and the active zone cytomatrix in nerve terminals. However, the distribution of SAD-B in the peripheral nervous system remains elusive. Here, we show that SAD-B is specifically localized to neuromuscular junctions. Although the active zone protein bassoon showed a punctated signal indicating its localization to motor end plates, SAD-B shows relatively diffuse localization indicating its association with both the active zone and synaptic vesicles. Therefore, SAD kinase may regulate neurotransmitter release from motor end plates in a similar manner to its regulation of neurotransmitter release in the central nervous system.

  20. Urinary serine proteases and activation of ENaC in kidney

    DEFF Research Database (Denmark)

    Svenningsen, Per; Andersen, Henrik; Nielsen, Lise Hald

    2015-01-01

    with albuminuria compatible with impaired renal Na(+) excretion: hypertension and volume retention is secondary to proteinuria in, e.g., preeclampsia and nephrotic syndrome; plasma concentrations of renin, angiotensin II, and aldosterone are frequently suppressed in proteinuric conditions, e.g., preeclampsia......Serine proteases, both soluble and cell-attached, can activate the epithelial sodium channel (ENaC) proteolytically through release of a putative 43-mer inhibitory tract from the ectodomain of the γ-subunit. ENaC controls renal Na(+) excretion and loss-of-function mutations lead to low blood...... pressure, while gain-of-function mutations lead to impaired Na(+) excretion, hypertension, and hypokalemia. We review an emerging pathophysiological concept that aberrant glomerular filtration of plasma proteases, e.g., plasmin, prostasin, and kallikrein, contributes to proteolytic activation of ENaC, both...

  1. The action of neutrophil serine proteases on elastin and its precursor

    DEFF Research Database (Denmark)

    Heinz, Andrea; Jung, Michael C; Jahreis, Günther

    2012-01-01

    This study aimed to investigate the degradation of the natural substrates tropoelastin and elastin by the neutrophil-derived serine proteases human leukocyte elastase (HLE), proteinase 3 (PR3) and cathepsin G (CG). Focus was placed on determining their cleavage site specificities using mass...... spectrometric techniques. Moreover, the release of bioactive peptides from elastin by the three proteases was studied. Tropoelastin was comprehensively degraded by all three proteases, whereas less cleavage occurred in mature cross-linked elastin. An analysis of the cleavage site specificities of the three...... proteases in tropoelastin and elastin revealed that HLE and PR3 similarly tolerate hydrophobic and/or aliphatic amino acids such as Ala, Gly and Val at P(1), which are also preferred by CG. In addition, CG prefers the bulky hydrophobic amino acid Leu and accepts the bulky aromatic amino acids Phe and Tyr...

  2. Selective inhibition of plant serine hydrolases by agrochemicals revealed by competitive ABPP.

    Science.gov (United States)

    Kaschani, Farnusch; Nickel, Sabrina; Pandey, Bikram; Cravatt, Benjamin F; Kaiser, Markus; van der Hoorn, Renier A L

    2012-01-15

    Organophosphate and -phosphonates and their thio derivatives are often used in agroindustry as herbicides and insecticides, but their potential off-targets in the plant are poorly investigated. Here, we use competitive activity-based protein profiling (ABPP) of serine hydrolases (SHs) to detect targets of these agrochemicals and other compounds in Arabidopsis thaliana. Using broad-range and specific probes, and by overexpression of various SHs in planta, we are able to confirm eight SH-compound interactions, including selective inhibition of carboxylesterase CXE12, prolyloligopeptidase, methylesterase MES2 and tripeptidyl peptidase TPP2. These observations can be used for the design of novel probes and selective inhibitors and may help to assess physiological effects of agrochemicals on crop plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Potent and Selective Peptidyl Boronic Acid Inhibitors of the Serine Protease Prostate-Specific Antigen

    Science.gov (United States)

    LeBeau, Aaron M.; Singh, Pratap; Isaacs, John T.; Denmeade, Samuel R.

    2012-01-01

    SUMMARY Prostate cancer cells produce high (microgram to milligram/milliliter) levels of the serine protease Prostate-Specific Antigen (PSA). PSA is enzymatically active in the extracellular fluid surrounding prostate cancers but is found at 1,000- to 10,000-fold lower concentrations in the circulation, where it is inactivated due to binding to abundant serum protease inhibitors. The exclusive presence of high levels of active PSA within prostate cancer sites makes PSA an attractive candidate for targeted imaging and therapeutics. A synthetic approach based on a peptide substrate identified first peptide aldehyde and then boronic acid inhibitors of PSA. The best of these had the sequence Cbz-Ser-Ser-Lys-Leu-(boro)Leu, with a Ki for PSA of 65 nM. The inhibitor had a 60-fold higher Ki for chymotrypsin. A validated model of PSA’s catalytic site confirmed the critical interactions between the inhibitor and residues within the PSA enzyme. PMID:18635003

  4. Hide depilation and feather disintegration studies with keratinolytic serine protease from a novel Bacillus subtilis isolate.

    Science.gov (United States)

    Pillai, Priya; Archana, G

    2008-03-01

    Keratinases play an important role in biotechnological applications such as improvement of feather meal, enzymatic dehairing and production of amino acids or peptides from high molecular weight substrates. Bacillus subtilis P13, isolated from Vajreshwari hot spring (45-50 degrees C) near Mumbai, India, produces a neutral serine protease and has an optimum temperature of 65 degrees C. This enzyme preparation was keratinolytic in nature and could disintegrate whole chicken feathers, except for the remnants of shafts. The enzyme preparation also exhibited depilation of goat hides with the recovery of intact animal hair. The enzyme preparation could release peptides from ground feathers and bring about their weight reduction; however, similar action on hair was relatively weak. A single major PMSF-sensitive protease band could be detected upon zymogram analysis, indicating that a single enzyme may be responsible for feather degradation and hide depilation. The importance of these findings in the biotechnological application for feather and leather industries is discussed.

  5. The story of an exceptional serine protease, tissue-type plasminogen activator (tPA).

    Science.gov (United States)

    Hébert, M; Lesept, F; Vivien, D; Macrez, R

    2016-03-01

    The only acute treatment of ischemic stroke approved by the health authorities is tissue recombinant plasminogen activator (tPA)-induced thrombolysis. Under physiological conditions, tPA, belonging to the serine protease family, is secreted by endothelial and brain cells (neurons, astrocytes, microglia, oligodendrocytes). Although revascularisation induced by tPA is beneficial during a stroke, research over the past 20 years shows that tPA can also be deleterious for the brain parenchyma. Thus, in this review of the literature, after a brief history on the discovery of tPA, we reviewed current knowledge of mechanisms by which tPA can influence brain function in physiological and pathological conditions. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  6. Global histone analysis by mass spectrometry reveals a high content of acetylated lysine residues in the malaria parasite Plasmodium falciparum

    DEFF Research Database (Denmark)

    Trelle, Morten Beck; Salcedo-Amaya, Adriana M; Cohen, Adrian

    2009-01-01

    Post-translational modifications (PTMs) of histone tails play a key role in epigenetic regulation of gene expression in a range of organisms from yeast to human, however, little is known about histone proteins from the parasite that causes malaria in humans, Plasmodium falciparum. We characterize...... comprehensive map of histone modifications in Plasmodium falciparum and highlight the utility of tandem MS for detailed analysis of peptides containing multiple PTMs....

  7. Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains

    DEFF Research Database (Denmark)

    Jespersen, Jakob S.; Wang, Christian W.; Mkumbaye, Sixbert I.

    2016-01-01

    Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding hum...... the hypothesis that the CIDRα1-EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction....

  8. Allelic Diversity and Geographical Distribution of the Gene Encoding Plasmodium falciparum Merozoite Surface Protein-3 in Thailand.

    Science.gov (United States)

    Sawaswong, Vorthon; Simpalipan, Phumin; Siripoon, Napaporn; Harnyuttanakorn, Pongchai; Pattaradilokrat, Sittiporn

    2015-04-01

    Merozoite surface proteins (MSPs) of malaria parasites play critical roles during the erythrocyte invasion and so are potential candidates for malaria vaccine development. However, because MSPs are often under strong immune selection, they can exhibit extensive genetic diversity. The gene encoding the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum displays 2 allelic types, K1 and 3D7. In Thailand, the allelic frequency of the P. falciparum msp-3 gene was evaluated in a single P. falciparum population in Tak at the Thailand and Myanmar border. However, no study has yet looked at the extent of genetic diversity of the msp-3 gene in P. falciparum populations in other localities. Here, we genotyped the msp-3 alleles of 63 P. falciparum samples collected from 5 geographical populations along the borders of Thailand with 3 neighboring countries (Myanmar, Laos, and Cambodia). Our study indicated that the K1 and 3D7 alleles coexisted, but at different proportions in different Thai P. falciparum populations. K1 was more prevalent in populations at the Thailand-Myanmar and Thailand-Cambodia borders, whilst 3D7 was more prevalent at the Thailand-Laos border. Global analysis of the msp-3 allele frequencies revealed that proportions of K1 and 3D7 alleles of msp-3 also varied in different continents, suggesting the divergence of malaria parasite populations. In conclusion, the variation in the msp-3 allelic patterns of P. falciparum in Thailand provides fundamental knowledge for inferring the P. falciparum population structure and for the best design of msp-3 based malaria vaccines.

  9. Epigenetic Activation of ASCT2 in the Hippocampus Contributes to Depression-Like Behavior by Regulating D-Serine in Mice

    Directory of Open Access Journals (Sweden)

    Jiesi Wang

    2017-05-01

    Full Text Available The roles of D-serine in depression are raised concerned recently as an intrinsic co-agonist for the NMDA receptor. However, the mechanisms underlying its regulation are not fully elucidated. ASCT2 is a Na+-dependent D-serine transporter. We found that decreased D-serine and increased hippocampal ASCT2 levels correlated with chronic social defeat stress (CSDS in mice. Lentivirus-mediated shRNA-mediated knockdown of ASCT2 and the administration of exogenous D-serine in the hippocampus alleviated CSDS-induced social avoidance and immobility. In vivo and in vitro experiments revealed that upregulation of ASCT2 expression in CSDS was regulated through histone hyper-acetylation, not DNA methylation in its promoter region. Immunohistochemistry demonstrated the co-localization of ASCT2 and D-serine. Uptake of D-serine by ASCT2 was demonstrated by in vivo and in vitro experiments. Our results indicate that CSDS induces ASCT2 expression through epigenetic activation and decreases hippocampal D-serine levels, leading to social avoidance, and immobility. Thus, targeting D-serine transport represents an attractive new strategy for treating depression.

  10. Comparative Mitogenomics of Plant Bugs (Hemiptera: Miridae): Identifying the AGG Codon Reassignments between Serine and Lysine

    Science.gov (United States)

    Wang, Pei; Song, Fan; Cai, Wanzhi

    2014-01-01

    Insect mitochondrial genomes are very important to understand the molecular evolution as well as for phylogenetic and phylogeographic studies of the insects. The Miridae are the largest family of Heteroptera encompassing more than 11,000 described species and of great economic importance. For better understanding the diversity and the evolution of plant bugs, we sequence five new mitochondrial genomes and present the first comparative analysis of nine mitochondrial genomes of mirids available to date. Our result showed that gene content, gene arrangement, base composition and sequences of mitochondrial transcription termination factor were conserved in plant bugs. Intra-genus species shared more conserved genomic characteristics, such as nucleotide and amino acid composition of protein-coding genes, secondary structure and anticodon mutations of tRNAs, and non-coding sequences. Control region possessed several distinct characteristics, including: variable size, abundant tandem repetitions, and intra-genus conservation; and was useful in evolutionary and population genetic studies. The AGG codon reassignments were investigated between serine and lysine in the genera Adelphocoris and other cimicomorphans. Our analysis revealed correlated evolution between reassignments of the AGG codon and specific point mutations at the antidocons of tRNALys and tRNASer(AGN). Phylogenetic analysis indicated that mitochondrial genome sequences were useful in resolving family level relationship of Cimicomorpha. Comparative evolutionary analysis of plant bug mitochondrial genomes allowed the identification of previously neglected coding genes or non-coding regions as potential molecular markers. The finding of the AGG codon reassignments between serine and lysine indicated the parallel evolution of the genetic code in Hemiptera mitochondrial genomes. PMID:24988409

  11. C. elegans serine-threonine kinase KIN-29 modulates TGFβ signaling and regulates body size formation

    Directory of Open Access Journals (Sweden)

    Cohen Stephen

    2005-04-01

    Full Text Available Background In C. elegans there are two well-defined TGFβ-like signaling pathways. The Sma/Mab pathway affects body size morphogenesis, male tail development and spicule formation while the Daf pathway regulates entry into and exit out of the dauer state. To identify additional factors that modulate TGFβ signaling in the Sma/Mab pathway, we have undertaken a genetic screen for small animals and have identified kin-29. Results kin-29 encodes a protein with a cytoplasmic serine-threonine kinase and a novel C-terminal domain. The kinase domain is a distantly related member of the EMK (ELKL motif kinase family, which interacts with microtubules. We show that the serine-threonine kinase domain has in vitro activity. kin-29 mutations result in small animals, but do not affect male tail morphology as do several of the Sma/Mab signal transducers. Adult worms are smaller than the wild-type, but also develop more slowly. Rescue by kin-29 is achieved by expression in neurons or in the hypodermis. Interaction with the dauer pathway is observed in double mutant combinations, which have been seen with Sma/Mab pathway mutants. We show that kin-29 is epistatic to the ligand dbl-1, and lies upstream of the Sma/Mab pathway target gene, lon-1. Conclusion kin-29 is a new modulator of the Sma/Mab pathway. It functions in neurons and in the hypodermis to regulate body size, but does not affect all TGFβ outputs, such as tail morphogenesis.

  12. Pest protection conferred by a Beta vulgaris serine proteinase inhibitor gene.

    Directory of Open Access Journals (Sweden)

    Ann C Smigocki

    Full Text Available Proteinase inhibitors provide a means of engineering plant resistance to insect pests. A Beta vulgaris serine proteinase inhibitor gene (BvSTI was fused to the constitutive CaMV35S promoter for over-expression in Nicotiana benthamiana plants to study its effect on lepidopteran insect pests. Independently derived BvSTI transgenic tobacco T2 homozygous progeny were shown to have relatively high BvSTI gene transcript levels. BvSTI-specific polyclonal antibodies cross-reacted with the expected 30 kDA recombinant BvSTI protein on Western blots. In gel trypsin inhibitor activity assays revealed a major clear zone that corresponded to the BvSTI proteinase inhibitor that was not detected in the untransformed control plants. BvSTI-transgenic plants were bioassayed for resistance to five lepidopteran insect pests. Spodoptera frugiperda, S. exigua and Manduca sexta larvae fed BvSTI leaves had significant reductions in larval weights as compared to larvae fed on untransformed leaves. In contrast, larval weights increased relative to the controls when Heliothis virescens and Agrotis ipsilon larvae were fed on BvSTI leaves. As the larvae entered the pupal stage, pupal sizes reflected the overall larval weights. Some developmental abnormalities of the pupae and emerging moths were noted. These findings suggest that the sugar beet BvSTI gene may prove useful for effective control of several different lepidopteran insect pests in genetically modified tobacco and other plants. The sugar beet serine proteinase inhibitor may be more effective for insect control because sugar beet is cropped in restricted geographical areas thus limiting the exposure of the insects to sugar beet proteinase inhibitors and build up of non-sensitive midgut proteases.

  13. LFA-1 and Mac-1 integrins bind to the serine/threonine-rich domain of thrombomodulin

    Energy Technology Data Exchange (ETDEWEB)

    Kawamoto, Eiji [Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507 (Japan); Emergency and Critical Care Center, Mie University Hospital, 2-174 Edobashi, Tsu 514-8507 (Japan); Okamoto, Takayuki, E-mail: okamotot@doc.medic.mie-u.ac.jp [Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507 (Japan); Takagi, Yoshimi [Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507 (Japan); Honda, Goichi [Medical Affairs Department, Asahi Kasei Pharma Corporation, 1-105 Kanda Jinbo-cho, Chiyoda-ku, Tokyo 101-8101 (Japan); Suzuki, Koji [Faculty of Pharmaceutical Science, Suzuka University of Medical Science, 3500-3, Minamitamagaki-cho, Suzuka, Mie 513-8679 (Japan); Imai, Hiroshi [Emergency and Critical Care Center, Mie University Hospital, 2-174 Edobashi, Tsu 514-8507 (Japan); Shimaoka, Motomu, E-mail: shimaoka@doc.medic.mie-u.ac.jp [Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507 (Japan)

    2016-05-13

    LFA-1 (αLβ2) and Mac-1 (αMβ2) integrins regulate leukocyte trafficking in health and disease by binding primarily to IgSF ligand ICAM-1 and ICAM-2 on endothelial cells. Here we have shown that the anti-coagulant molecule thrombomodulin (TM), found on the surface of endothelial cells, functions as a potentially new ligand for leukocyte integrins. We generated a recombinant extracellular domain of human TM and Fc fusion protein (TM-domains 123-Fc), and showed that pheripheral blood mononuclear cells (PBMCs) bind to TM-domains 123-Fc dependent upon integrin activation. We then demonstrated that αL integrin-blocking mAb, αM integrin-blocking mAb, and β2 integrin-blocking mAb inhibited the binding of PBMCs to TM-domains 123-Fc. Furthermore, we show that the serine/threonine-rich domain (domain 3) of TM is required for the interaction with the LFA-1 (αLβ2) and Mac-1 (αMβ2) integrins to occur on PBMCs. These results demonstrate that the LFA-1 and Mac-1 integrins on leukocytes bind to TM, thereby establishing the molecular and structural basis underlying LFA-1 and Mac-1 integrin interaction with TM on endothelial cells. In fact, integrin-TM interactions might be involved in the dynamic regulation of leukocyte adhesion with endothelial cells. - Highlights: • LFA-1 and Mac-1 integrins bind to the anti-coagulant molecule thrombomodulin. • The serine/threonine-rich domain of thrombomodulin is essential to interact with the LFA-1 and Mac-1 integrins on PBMCs. • Integrin-TM interactions might be involved in the dynamic regulation of leukocyte adhesion with endothelial cells.

  14. Contribution of cutinase serine 42 side chain to the stabilization of the oxyanion transition state.

    Science.gov (United States)

    Nicolas, A; Egmond, M; Verrips, C T; de Vlieg, J; Longhi, S; Cambillau, C; Martinez, C

    1996-01-16

    Cutinase from the fungus Fusarium solani pisi is a lipolytic enzyme able to hydrolyze both aggregated and soluble substrates. It therefore provides a powerful tool for probing the mechanisms underlying lipid hydrolysis. Lipolytic enzymes have a catalytic machinery similar to those present in serine proteinases. It is characterized by the triad Ser, His, and Asp (Glu) residues, by an oxyanion binding site that stabilizes the transition state via hydrogen bonds with two main chain amide groups, and possibly by other determinants. It has been suggested on the basis of a covalently bond inhibitor that the cutinase oxyanion hole may consist not only of two main chain amide groups but also of the Ser42 O gamma side chain. Among the esterases and the serine and the cysteine proteases, only Streptomyces scabies esterase, subtilisin, and papain, respectively, have a side chain residue which is involved in the oxyanion hole formation. The position of the cutinase Ser42 side chain is structurally conserved in Rhizomucor miehei lipase with Ser82 O gamma, in Rhizopus delemar lipase with Thr83 O gamma 1, and in Candida antartica B lipase with Thr40 O gamma 1. To evaluate the increase in the tetrahedral intermediate stability provided by Ser42 O gamma, we mutated Ser42 into Ala. Furthermore, since the proper orientation of Ser42 O gamma is directed by Asn84, we mutated Asn84 into Ala, Leu, Asp, and Trp, respectively, to investigate the contribution of this indirect interaction to the stabilization of the oxyanion hole. The S42A mutation resulted in a drastic decrease in the activity (450-fold) without significantly perturbing the three-dimensional structure. The N84A and N84L mutations had milder kinetic effects and did not disrupt the structure of the active site, whereas the N84W and N84D mutations abolished the enzymatic activity due to drastic steric and electrostatic effects, respectively.

  15. Role of disulphide bonds in a thermophilic serine protease aqualysin I from Thermus aquaticus YT-1.

    Science.gov (United States)

    Sakaguchi, Masayoshi; Takezawa, Makoto; Nakazawa, Rie; Nozawa, Kazutaka; Kusakawa, Taro; Nagasawa, Takeshi; Sugahara, Yasusato; Kawakita, Masao

    2008-05-01

    A thermophilic serine protease, Aqualysin I, from Thermus aquaticus YT-1 has two disulphide bonds, which are also found in a psychrophilic serine protease from Vibrio sp. PA-44 and a proteinase K-like enzyme from Serratia sp. at corresponding positions. To understand the significance of these disulphide bonds in aqualysin I, we prepared mutants C99S, C194S and C99S/C194S (WSS), in which Cys69-Cys99, Cys163-Cys194 and both of these disulphide bonds, respectively, were disrupted by replacing Cys residues with Ser residues. All mutants were expressed stably in Escherichia coli. The C99S mutant was 68% as active as the wild-type enzyme at 40 degrees C in terms of k(cat) value, while C194S and WSS were only 6 and 3%, respectively, as active, indicating that disulphide bond Cys163-Cys194 is critically important for maintaining proper catalytic site conformation. Mutants C194S and WSS were less thermostable than wild-type enzyme, with a half-life at 90 degrees C of 10 min as compared to 45 min of the latter and with transition temperatures on differential scanning calorimetry of 86.7 degrees C and 86.9 degrees C, respectively. Mutant C99S was almost as stable as the wild-type aqualysin I. These results indicate that the disulphide bond Cys163-Cys194 is more important for catalytic activity and conformational stability of aqualysin I than Cys67-Cys99.

  16. Application of Asian pumpkin (Cucurbita ficifolia) serine proteinase for production of biologically active peptides from casein.

    Science.gov (United States)

    Dąbrowska, Anna; Szołtysik, Marek; Babij, Konrad; Pokora, Marta; Zambrowicz, Aleksandra; Chrzanowska, Józefa

    2013-01-01

    The main objective of this study was to determine potential application of a serine proteinase derived from Asian pumpkin for obtaining biologically active peptides from casein. The course of casein hydrolysis by three doses of the enzyme (50, 150, 300 U/mg of protein) was monitored for 24 hours by the determinations of: hydrolysis degree DH (%), free amino group content (μmole Gly/g), RP HPLC peptide profiles and by polyacrylamide gel electrophoresis. In all hydrolyzates analyzed antioxidant activities were determined using three tests: the ability to reduce iron ions in FRAP test, the ability to scavenge free radicals in DPPH test, and Fe(2+) chelating activity. The antimicrobial activity of obtained peptide fractions was determined as the ability to inhibit the growth of Escherichia coli, Bacillus cereus and Pseudomonas fluorescens in a diffusion plate test. The deepest degradation, expressed as the DH [%] and the free amino group content (67% and 7528 µmole Gly/mg, respectively), was noted in samples hydrolyzed with 300 U/ml of enzyme for 24 hours, while in other samples the determined values were about three and two times lower. The results were in agreement with the peptide profiles obtained by RP HPLC. The highest antioxidative activities determined in all tests were seen for the casein hydrolysate obtained with 300 U/mg protein of serine proteinase after 24 h of reaction (2.15 µM Trolox/mg, 96.15 µg Fe(3+)/mg, 814.97 µg Fe(2+)/mg). Antimicrobial activity was presented in three preparations. In other samples no antimicrobial activity was detected.

  17. Endothelin-1 stimulates catalase activity through the PKCδ mediated phosphorylation of Serine 167

    Science.gov (United States)

    Rafikov, Ruslan; Kumar, Sanjiv; Aggarwal, Saurabh; Hou, Yali; Kangath, Archana; Pardo, Daniel; Fineman, Jeffrey R.; Black, Stephen M.

    2013-01-01

    Our previous studies have shown that endothelin-1 (ET-1) stimulates catalase activity in endothelial cells and lambs with acute increases in pulmonary blood flow (PBF), without altering gene expression. The purpose of this study was to investigate the molecular mechanism by which this occurs. Exposing pulmonary arterial endothelial cells (PAEC) to ET-1 increased catalase activity and decreased cellular hydrogen peroxide (H2O2) levels. These changes correlated with an increase in serine phosphorylated catalase. Using the inhibitory peptide δV1.1, this phosphorylation was shown to be PKCδ dependent. Mass spectrometry identified serine167 as the phosphorylation site. Site-directed mutagenesis was used to generate a phospho-mimic (S167D) catalase. Activity assays using recombinant protein purified from E.coli or transiently transfected COS-7 cells, demonstrated that S167D-catalase had an increased ability to degrade H2O2 compared to the wildtype enzyme. Using a phospho-specific antibody, we were able to verify that pS167 catalase levels are modulated in lambs with acute increases in PBF in the presence and absence of the ET receptor antagonist, tezosentan. S167 is being located on the dimeric interface suggesting it could be involved in regulating the formation of catalase tetramers. To evaluate this possibility we utilized analytical gel-filtration to examine the multimeric structure of recombinant wildtype- and S167D-catalase. We found that recombinant wildtype catalase was present as a mixture of monomers and dimers while S167D catalase was primarily tetrameric. Further, the incubation of wildtype catalase with PKCδ was sufficient to convert wildtype catalase into a tetrameric structure. In conclusion, this is the first report indicating that the phosphorylation of catalase regulates its multimeric structure and activity. PMID:24211614

  18. Estimating the global clinical burden of Plasmodium falciparum malaria in 2007.

    Directory of Open Access Journals (Sweden)

    Simon I Hay

    2010-06-01

    Full Text Available The epidemiology of malaria makes surveillance-based methods of estimating its disease burden problematic. Cartographic approaches have provided alternative malaria burden estimates, but there remains widespread misunderstanding about their derivation and fidelity. The aims of this study are to present a new cartographic technique and its application for deriving global clinical burden estimates of Plasmodium falciparum malaria for 2007, and to compare these estimates and their likely precision with those derived under existing surveillance-based approaches.In seven of the 87 countries endemic for P. falciparum malaria, the health reporting infrastructure was deemed sufficiently rigorous for case reports to be used verbatim. In the remaining countries, the mapped extent of unstable and stable P. falciparum malaria transmission was first determined. Estimates of the plausible incidence range of clinical cases were then calculated within the spatial limits of unstable transmission. A modelled relationship between clinical incidence and prevalence was used, together with new maps of P. falciparum malaria endemicity, to estimate incidence in areas of stable transmission, and geostatistical joint simulation was used to quantify uncertainty in these estimates at national, regional, and global scales. Combining these estimates for all areas of transmission risk resulted in 451 million (95% credible interval 349-552 million clinical cases of P. falciparum malaria in 2007. Almost all of this burden of morbidity occurred in areas of stable transmission. More than half of all estimated P. falciparum clinical cases and associated uncertainty occurred in India, Nigeria, the Democratic Republic of the Congo (DRC, and Myanmar (Burma, where 1.405 billion people are at risk. Recent surveillance-based methods of burden estimation were then reviewed and discrepancies in national estimates explored. When these cartographically derived national estimates were ranked

  19. STANDARDIZATION OF PROCEDURES OF Plasmodium falciparum ANTIGEN PREPARATION FOR SEROLOGIC TESTS

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    Sandra L.M. AVILA

    1998-09-01

    Full Text Available The objective of the present study is to standardize the technical variables for preparation and storage of Plasmodium falciparum and of antigen components extracted with the amphoteric detergent Zwittergent. P. falciparum obtained from in vitro culture was stored at different temperatures and for different periods of time. For each variable, antigen components of the parasite were extracted in the presence or absence of protease inhibitors and submitted or not to later dialysis. Products were stored for 15, 30 and 60 days at different temperatures and immunological activity of each extract was determined by SDS-PAGE and ELISA using positive or negative standard sera for the presence of IgG directed to blood stage antigens of P. falciparum. Antigen extracts obtained from parasites stored at -20oC up to 10 days or at -70oC for 2 months presented the best results, showing well-defined bands on SDS-PAGE and Western blots and presenting absorbance values in ELISA that permitted safe differentiation between positive and negative sera.O objetivo deste estudo foi padronizar variáveis técnicas para o armazenamento de Plasmodium falciparum e de seus componentes antigênicos. Sedimentos de parasitas foram obtidos do cultivo in vitro de P.falciparum e estocados em diferentes temperaturas por diferentes períodos de tempo. De cada variável, foram extraídos os componentes antigênicos com detergente anfótero Zwittergent na presença e na ausência de inibidores de proteases e submetidos ou não a posterior diálise. Os produtos foram estocados por 15, 30 e 60 dias em diferentes temperaturas e caracterizados por SDS-PAGE. A atividade antigênica de cada extrato foi determinada por ELISA e Western blotting usando soros positivos e negativos para anticorpos IgG anti-formas eritrocitárias de P.falciparum. Os extratos antigênicos obtidos de parasitas estocados até 10 dias a _20ºC ou por 2 meses a _70ºC e tratados com inibidores de proteases, sob as

  20. Small serine recombination systems ParA-MRS and CinH-RS2 perform precise excision of plastid DNA

    Science.gov (United States)

    Selectable marker genes (SMGs) are necessary for selection of transgenic plants. However, once stable transformants have been identified, the marker gene is no longer needed. In this study, we demonstrate the use of the small serine recombination systems, ParA-MRS and CinH-RS2, to precisely excise ...

  1. Basal Levels of AMPA Receptor GluA1 Subunit Phosphorylation at Threonine 840 and Serine 845 in Hippocampal Neurons

    Science.gov (United States)

    Babiec, Walter E.; Guglietta, Ryan; O'Dell, Thomas J.

    2016-01-01

    Dephosphorylation of AMPA receptor (AMPAR) GluA1 subunits at two sites, serine 845 (S845) and threonine 840 (T840), is thought to be involved in NMDA receptor-dependent forms of long-term depression (LTD). Importantly, the notion that dephosphorylation of these sites contributes to LTD assumes that a significant fraction of GluA1 subunits are…

  2. Subcellular localization of an intracellular serine protease of 68 kDa in Leishmania (Leishmania amazonensis promastigotes

    Directory of Open Access Journals (Sweden)

    José Andrés Morgado-Díaz

    2005-07-01

    Full Text Available Here we report the subcellular localization of an intracellular serine protease of 68 kDa in axenic promastigotes of Leishmania (Leishmania amazonensis, using subcellular fractionation, enzymatic assays, immunoblotting, and immunocytochemistry. All fractions were evaluated by transmission electron microscopy and the serine protease activity was measured during the cell fractionation procedure using a-N-r-tosyl-L-arginine methyl ester (L-TAME as substrate, phenylmethylsulphone fluoride (PMSF and L-1-tosylamino-2-phenylethylchloromethylketone (TPCK as specific inhibitors. The enzymatic activity was detected mainly in a membranous vesicular fraction (6.5-fold enrichment relative to the whole homogenate, but also in a crude plasma membrane fraction (2.0-fold. Analysis by SDS-PAGE gelatin under reducing conditions demonstrated that the major proteolytic activity was found in a 68 kDa protein in all fractions studied. A protein with identical molecular weight was also recognized in immunoblots by a polyclonal antibody against serine protease (anti-SP, with higher immunoreactivity in the vesicular fraction. Electron microscopic immunolocalization using the same polyclonal antibody showed the enzyme present at the cell surface, as well as in cytoplasmic membranous compartments of the parasite. Our findings indicate that the internal location of this serine protease in L. amazonensis is mainly restricted to the membranes of intracellular compartments resembling endocytic/exocytic elements.

  3. Mannan-binding lectin and mannan-binding lectin-associated serine protease 2 in acute pancreatitis

    DEFF Research Database (Denmark)

    Novovic, Srdan; Andersen, Anders; Ersbøll, Annette Kjær

    2011-01-01

    Complement activation may play a prominent role in acute pancreatitis (AP). Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) participate in complement activation. The objective of the present study was to evaluate the role of MBL and MASP-2 as markers in AP with regard...

  4. The Serine Protease Inhibitor Neuroserpin Is Required for Normal Synaptic Plasticity and Regulates Learning and Social Behavior

    Science.gov (United States)

    Reumann, Rebecca; Vierk, Ricardo; Zhou, Lepu; Gries, Frederice; Kraus, Vanessa; Mienert, Julia; Romswinkel, Eva; Morellini, Fabio; Ferrer, Isidre; Nicolini, Chiara; Fahnestock, Margaret; Rune, Gabriele; Glatzel, Markus; Galliciotti, Giovanna

    2017-01-01

    The serine protease inhibitor neuroserpin regulates the activity of tissue-type plasminogen activator (tPA) in the nervous system. Neuroserpin expression is particularly prominent at late stages of neuronal development in most regions of the central nervous system (CNS), whereas it is restricted to regions related to learning and memory in the…

  5. Syntheses of sulphurated amino-acids from cystein, serine and phosphoserine using pyridoxal and a metal as catalysts (1961)

    International Nuclear Information System (INIS)

    Ratsisalovanina, O.; Chapeville, F.; Fromageot, P.

    1961-01-01

    Pyridoxal or pyridoxal phosphate in the presence of certain metals catalyzes the substitution of the -SH, -OH, or -O-PO 3 H 2 groups of cysteine, serine or phosphoserine by a -SH or -SO 3 H group brought by mineral sulfide or sulfite. (authors) [fr

  6. Studies of Environmental Risk Factors in Amyotrophic Lateral Sclerosis (ALS) and a Phase I Clinical Trial of L-Serine.

    Science.gov (United States)

    Bradley, Walter G; Miller, R X; Levine, T D; Stommel, E W; Cox, P A

    2018-01-01

    β-N-Methylamino-L-alanine (BMAA) has been linked to Guam ALS/PDC and shown to produce neurodegeneration in vitro and in vivo (Drosophila, mice, rats, primates). BMAA misincorporation into neuroproteins produces protein misfolding and is inhibited by L-serine. Case-control studies in Northern New England indicate that living near to water-bodies with cyanobacterial blooms increases the risk of developing amyotrophic lateral sclerosis (ALS). The distribution of addresses of ALS cases in New Hampshire, Vermont, and Florida was compared to that of controls. Areas of statistically significantly increased numbers of ALS cases were examined for sources of environmental toxins. A phase I trial of oral L-serine was performed in 20 ALS patients (0.5 to 15 g twice daily). Safety and tolerability were assessed by comparing the rate of deterioration with 430 matched placebo controls. The distribution of residential addresses of ALS cases in New England and Florida revealed many areas where the age- and gender-adjusted frequency of ALS was greater than expected (P ALS patients suggests that residential exposure to environmental pollutants may play an important role in the etiology of ALS. L-Serine in doses up to 15 g twice daily appears to be safe in patients with ALS. Exploratory studies of efficacy suggested that L-serine might slow disease progression. A phase II trial is planned.

  7. Molecular cloning and tissue-specific expression analysis of mouse spinesin, a type II transmembrane serine protease 5

    International Nuclear Information System (INIS)

    Watanabe, Yoshihisa; Okui, Akira; Mitsui, Shinichi; Kawarabuki, Kentaro; Yamaguchi, Tatsuyuki; Uemura, Hidetoshi; Yamaguchi, Nozomi

    2004-01-01

    We have previously reported novel serine proteases isolated from cDNA libraries of the human and mouse central nervous system (CNS) by PCR using degenerate oligodeoxyribonucleotide primers designed on the basis of the serine protease motifs, AAHC and DSGGP. Here we report a newly isolated serine protease from the mouse CNS. This protease is homologous (77.9% identical) to human spinesin type II transmembrane serine protease 5. Mouse spinesin (m-spinesin) is also composed of (from the N-terminus) a short cytoplasmic domain, a transmembrane domain, a stem region containing a scavenger-receptor-like domain, and a serine protease domain, as is h-spinesin. We also isolated type 1, type 2, and type 3 variant cDNAs of m-spinesin. Full-length spinesin (type 4) and type 3 contain all the domains, whereas type 1 and type 2 variants lack the cytoplasmic, transmembrane, and scavenger-receptor-like domains. Subcellular localization of the variant forms was analyzed using enhanced green fluorescent protein (EGFP) fusion proteins. EGFP-type 4 fusion protein was predominantly localized to the ER, Golgi apparatus, and plasma membrane, whereas EGFP-type 1 was localized to the cytoplasm, reflecting differential classification of m-spinesin variants into transmembrane and cytoplasmic types. We analyzed the distribution of m-spinesin variants in mouse tissues, using RT-PCR with variant-specific primer sets. Interestingly, transmembrane-type spinesin, types 3 and 4, was specifically expressed in the spinal cord, whereas cytoplasmic type, type 1, was expressed in multiple tissues, including the cerebrum and cerebellum. Therefore, m-spinesin variants may have distinct biological functions arising from organ-specific variant expression

  8. Identification of B cell recognized linear epitopes in a snake venom serine proteinase from the central American bushmaster Lachesis stenophrys.

    Science.gov (United States)

    Madrigal, M; Alape-Girón, A; Barboza-Arguedas, E; Aguilar-Ulloa, W; Flores-Díaz, M

    2017-12-15

    Snake venom serine proteinases are toxins that perturb hemostasis acting on proteins from the blood coagulation cascade, the fibrinolytic or the kallikrein-kinin system. Despite the relevance of these enzymes in envenomations by viper bites, the characterization of the antibody response to these toxins at the molecular level has not been previously addressed. In this work surface-located B cell recognized linear epitopes from a Lachesis stenophrys venom serine proteinase (UniProt accession number Q072L7) were predicted using an artificial neuronal network at the ABCpred server, the corresponding peptides were synthesized and their immunoreactivity was analyzed against a panel of experimental and therapeutic antivenoms. A molecular model of the L. stenophrys enzyme was built using as a template the structure of the D. acutus Dav-PA serine proteinase (Q9I8X1), which displays the highest degree of sequence similarity to the L. stenophrys enzyme among proteins of known 3D structure, and the surface-located epitopes were identified in the protein model using iCn3D. A total of 13 peptides corresponding to the surface exposed predicted epitopes from L. stenophrys serine proteinase were synthesized and, their reactivity with a rabbit antiserum against the recombinant enzyme and a panel of antivenoms was evaluated by a capture ELISA. Some of the epitopes recognized by monospecific and polyspecific antivenoms comprise sequences overlapping motifs conserved in viper venom serine proteinases. The identification and characterization of relevant epitopes recognized by B cells in snake venom toxins may provide valuable information for the preparation of immunogens that help in the production of improved therapeutic antivenoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Autocrine motility factor (neuroleukin, phosphohexose isomerase) induces cell movement through 12-lipoxygenase-dependent tyrosine phosphorylation and serine dephosphorylation events.

    Science.gov (United States)

    Timár, J; Tóth, S; Tóvári, J; Paku, S; Raz, A

    1999-01-01

    Autocrine motility factor (AMF) is one of the motility cytokines regulating tumor cell migration, therefore identification of the signaling pathway coupled with it has critical importance. Previous studies revealed several elements of this pathway predominated by lipoxygenase-PKC activations but the role for tyrosine kinases remained questionable. Motility cytokines frequently have mitogenic effect as well, producing activation of overlapping signaling pathways therefore we have used B16a melanoma cells as models where AMF has exclusive motility effect. Our studies revealed that in B16a cells AMF initiated rapid (1-5 min) activation of the protein tyrosine kinase (PTK) cascade inducing phosphorylation of 179, 125, 95 and 40/37 kD proteins which was mediated by upstream cyclo- and lipoxygenases. The phosphorylated proteins were localized to the cortical actin-stress fiber attachment zones in situ by confocal microscopy. On the other hand, AMF receptor activation induced significant decrease in overall serine-phosphorylation level of cellular proteins accompanied by serine phosphorylation of 200, 90, 78 and 65 kd proteins. The decrease in serine phosphorylation was independent of PTKs, PKC as well as cyclo- and lipoxygenases. However, AMF induced robust translocation of PKCalpha to the stress fibers and cortical actin suggesting a critical role for this kinase in the generation of the motility signal. Based on the significant decrease in serine phosphorylation after AMF stimulus in B16a cells we postulated the involvement of putative serine/threonine phosphatase(s) upstream lipoxygenase and activation of the protein tyrosine kinase cascade downstream cyclo- and lipoxygenase(s) in the previously identified autocrine motility signal.

  10. Skeletal muscle PLIN3 and PLIN5 are serine phosphorylated at rest and following lipolysis during adrenergic or contractile stimulation

    Science.gov (United States)

    MacPherson, Rebecca E K; Vandenboom, Rene; Roy, Brian D; Peters, Sandra J

    2013-01-01

    In adipose tissue, access of adipose triglyceride and hormone-sensitive lipases (ATGL and HSL) to the lipid droplet depends on PLIN1 phosphorylation, however, PLIN1 is not expressed in skeletal muscle and the phosphorylation of the expressed PLINs has yet to be investigated. Further, direct interactions between skeletal muscle PLINs and HSL are unknown. We investigated the isolated and combined effects of epinephrine and contraction on PLIN-to-lipase interactions as well as phosphorylation. Isolated rat solei were assigned to one of four 30 min in vitro conditions (25°C): (1) rest; (2) intermittent tetanic stimulation (60 Hz for 150 msec; train rate 20/min); (3) 5 nmol/L epinephrine; (4) intermittent tetanic stimulation and 5 nmol/L epinephrine. Immunoprecipitation of serine phosphorylated proteins followed by Western blotting for PLIN2, PLIN3, PLIN5, revealed that only PLIN2 is not phosphorylated under any of the experimental conditions. This is the first study to show that in whole rat skeletal muscle PLIN3 and PLIN5 are serine phosphorylated. The degree of serine phosphorylation remained unchanged following adrenergic and/or contractile stimulation. Oil red O staining of muscle sections for lipid content shows a significant decrease following each condition, confirming lipolysis occurred (P < 0.05). PLIN2, 3, and 5 all interact with HSL and ATGL, but these interactions were unchanged following treatments. Our results show that in skeletal muscle, PLIN2 is not serine phosphorylated at rest or with lipolytic stimulation and that while PLIN3, PLIN5 are serine phosphorylated at rest, the degree of phosphorylation does not change with lipolytic stimulation. PMID:24303154

  11. Inferring selection in the Anopheles gambiae species complex: an example from immune-related serine protease inhibitors

    Directory of Open Access Journals (Sweden)

    Little Tom J

    2009-06-01

    Full Text Available Abstract Background Mosquitoes of the Anopheles gambiae species complex are the primary vectors of human malaria in sub-Saharan Africa. Many host genes have been shown to affect Plasmodium development in the mosquito, and so are expected to engage in an evolutionary arms race with the pathogen. However, there is little conclusive evidence that any of these mosquito genes evolve rapidly, or show other signatures of adaptive evolution. Methods Three serine protease inhibitors have previously been identified as candidate immune system genes mediating mosquito-Plasmodium interaction, and serine protease inhibitors have been identified as hot-spots of adaptive evolution in other taxa. Population-genetic tests for selection, including a recent multi-gene extension of the McDonald-Kreitman test, were applied to 16 serine protease inhibitors and 16 other genes sampled from the An. gambiae species complex in both East and West Africa. Results Serine protease inhibitors were found to show a marginally significant trend towards higher levels of amino acid diversity than other genes, and display extensive genetic structuring associated with the 2La chromosomal inversion. However, although serpins are candidate targets for strong parasite-mediated selection, no evidence was found for rapid adaptive evolution in these genes. Conclusion It is well known that phylogenetic and population history in the An. gambiae complex can present special problems for the application of standard population-genetic tests for selection, and this may explain the failure of this study to detect selection acting on serine protease inhibitors. The pitfalls of uncritically applying these tests in this species complex are highlighted, and the future prospects for detecting selection acting on the An. gambiae genome are discussed.

  12. Analysis of Plasmodium falciparum diversity in natural infections by deep sequencing

    Science.gov (United States)

    Manske, Magnus; Miotto, Olivo; Campino, Susana; Auburn, Sarah; Almagro-Garcia, Jacob; Maslen, Gareth; O’Brien, Jack; Djimde, Abdoulaye; Doumbo, Ogobara; Zongo, Issaka; Ouedraogo, Jean-Bosco; Michon, Pascal; Mueller, Ivo; Siba, Peter; Nzila, Alexis; Borrmann, Steffen; Kiara, Steven M.; Marsh, Kevin; Jiang, Hongying; Su, Xin-Zhuan; Amaratunga, Chanaki; Fairhurst, Rick; Socheat, Duong; Nosten, Francois; Imwong, Mallika; White, Nicholas J.; Sanders, Mandy; Anastasi, Elisa; Alcock, Dan; Drury, Eleanor; Oyola, Samuel; Quail, Michael A.; Turner, Daniel J.; Rubio, Valentin Ruano; Jyothi, Dushyanth; Amenga-Etego, Lucas; Hubbart, Christina; Jeffreys, Anna; Rowlands, Kate; Sutherland, Colin; Roper, Cally; Mangano, Valentina; Modiano, David; Tan, John C.; Ferdig, Michael T.; Amambua-Ngwa, Alfred; Conway, David J.; Takala-Harrison, Shannon; Plowe, Christopher V.; Rayner, Julian C.; Rockett, Kirk A.; Clark, Taane G.; Newbold, Chris I.; Berriman, Matthew; MacInnis, Bronwyn; Kwiatkowski, Dominic P.

    2013-01-01

    Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. 1,2 Here we describe methods for large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short term culture. Analysis of 86,158 exonic SNPs that passed genotyping quality control in 227 samples from Africa, Asia and Oceania provides genome-wide estimates of allele frequency distribution, population structure and linkage disequilibrium. By comparing the genetic diversity of individual infections with that of the local parasite population, we derive a metric of within-host diversity that is related to the level of inbreeding in the population. An open-access web application has been established for exploration of regional differences in allele frequency and of highly differentiated loci in the P. falciparum genome. PMID:22722859

  13. Whole-Genome Scans Provide Evidence of Adaptive Evolution in Malawian Plasmodium falciparum Isolates

    DEFF Research Database (Denmark)

    Ocholla, Harold; Preston, Mark D; Mipando, Mwapatsa

    2014-01-01

    BACKGROUND:  Selection by host immunity and antimalarial drugs has driven extensive adaptive evolution in Plasmodium falciparum and continues to produce ever-changing landscapes of genetic variation. METHODS:  We performed whole-genome sequencing of 69 P. falciparum isolates from Malawi and used......, an area of high malaria transmission. Allele frequency-based tests provided evidence of recent population growth in Malawi and detected potential targets of host immunity and candidate vaccine antigens. Comparison of the sequence variation between isolates from Malawi and those from 5 geographically...... dispersed countries (Kenya, Burkina Faso, Mali, Cambodia, and Thailand) detected population genetic differences between Africa and Asia, within Southeast Asia, and within Africa. Haplotype-based tests of selection to sequence data from all 6 populations identified signals of directional selection at known...

  14. Evidence of endothelial inflammation, T cell activation, and T cell reallocation in uncomplicated Plasmodium falciparum malaria

    DEFF Research Database (Denmark)

    Elhassan, I M; Hviid, L; Satti, G

    1994-01-01

    endothelium. We measured plasma levels of soluble markers of endothelial inflammation and T cell activation in 32 patients suffering from acute, uncomplication P. falciparum malaria, as well as in 10 healthy, aparasitemic control donors. All donors were residents of a malaria-endemic area of Eastern State...... Sudan. In addition, we measured the T cell surface expression of the interleukin-2 receptor (CD25) and the lymphocyte function-associated antigen (LFA-1; CD11a/CD18). We found that the plasma levels of all inflammation and activation markers were significantly increased in the malaria patients compared...... with the control donors. In addition, we found a disease-induced depletion of T cells with high expression of the LFA-1 antigen, particularly in the CD4+ subset. The results obtained provide further support for the hypothesis of T cell reallocation to inflamed endothelium in acute P. falciparum malaria....

  15. Genetic Investigation of Tricarboxylic Acid Metabolism during the Plasmodium falciparum Life Cycle

    Directory of Open Access Journals (Sweden)

    Hangjun Ke

    2015-04-01

    Full Text Available New antimalarial drugs are urgently needed to control drug-resistant forms of the malaria parasite Plasmodium falciparum. Mitochondrial electron transport is the target of both existing and new antimalarials. Herein, we describe 11 genetic knockout (KO lines that delete six of the eight mitochondrial tricarboxylic acid (TCA cycle enzymes. Although all TCA KOs grew normally in asexual blood stages, these metabolic deficiencies halted life-cycle progression in later stages. Specifically, aconitase KO parasites arrested as late gametocytes, whereas α-ketoglutarate-dehydrogenase-deficient parasites failed to develop oocysts in the mosquitoes. Mass spectrometry analysis of 13C-isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development.

  16. Genetic investigation of tricarboxylic acid metabolism during the Plasmodium falciparum life cycle.

    Science.gov (United States)

    Ke, Hangjun; Lewis, Ian A; Morrisey, Joanne M; McLean, Kyle J; Ganesan, Suresh M; Painter, Heather J; Mather, Michael W; Jacobs-Lorena, Marcelo; Llinás, Manuel; Vaidya, Akhil B

    2015-04-07

    New antimalarial drugs are urgently needed to control drug-resistant forms of the malaria parasite Plasmodium falciparum. Mitochondrial electron transport is the target of both existing and new antimalarials. Herein, we describe 11 genetic knockout (KO) lines that delete six of the eight mitochondrial tricarboxylic acid (TCA) cycle enzymes. Although all TCA KOs grew normally in asexual blood stages, these metabolic deficiencies halted life-cycle progression in later stages. Specifically, aconitase KO parasites arrested as late gametocytes, whereas α-ketoglutarate-dehydrogenase-deficient parasites failed to develop oocysts in the mosquitoes. Mass spectrometry analysis of (13)C-isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Preferential transcription of conserved rif genes in two phenotypically distinct Plasmodium falciparum parasite lines

    DEFF Research Database (Denmark)

    Wang, Christian W; Magistrado, Pamela A; Nielsen, Morten A

    2009-01-01

    transcribed in the VAR2CSA-expressing parasite line. In addition, two rif genes were found transcribed at early and late intra-erythrocyte stages independently of var gene transcription. Rif genes are organised in groups and inter-genomic conserved gene families, suggesting that RIFIN sub-groups may have......Plasmodium falciparum variant surface antigens (VSA) are targets of protective immunity to malaria. Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) and repetitive interspersed family (RIFIN) proteins are encoded by the two variable multigene families, var and rif genes, respectively...... novel rif gene groups, rifA1 and rifA2, containing inter-genomic conserved rif genes, were identified. All rifA1 genes were orientated head-to-head with a neighbouring Group A var gene whereas rifA2 was present in all parasite genomes as a single copy gene with a unique 5' untranslated region. Rif...

  18. Evidence that Plasmodium falciparum diacylglycerol acyltransferase is essential for intraerythrocytic proliferation

    International Nuclear Information System (INIS)

    Palacpac, Nirianne Marie Q.; Hiramine, Yasushi; Seto, Shintaro; Hiramatsu, Ryuji; Horii, Toshihiro; Mitamura, Toshihide

    2004-01-01

    In triacylglycerol (TAG)-accumulating organisms, the physiological roles of diacylglycerol acyltransferase (DGAT), a principal enzyme in the major biosynthetic pathway for TAG, appear to be diverse. Apicomplexan parasite, Plasmodium falciparum, shows unique features in TAG metabolism and trafficking during intraerythrocytic development, and unlike most eukaryotes, only one open reading frame (ORF) encoding a candidate DGAT could be found in its genome. However, whether this candidate ORF encodes P. falciparum DGAT and its physiological relevance have not been assessed. Here, we demonstrate that the ORF is transcribed as a ∼3.6 kb single mRNA throughout intraerythrocytic development, markedly elevated at trophozoite, schizont, and segmented schizont, and indeed encodes a protein exhibiting DGAT activity. Further, we provide evidence that the parasite in which the ORF was disrupted via double crossover recombination cannot be enriched, implying a fundamental role of PfDGAT in intraerythrocytic proliferation

  19. Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields.

    Directory of Open Access Journals (Sweden)

    Lorena M Coronado

    Full Text Available The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways.

  20. Septic Shock due to Cytomegalovirus Infection in Acute Respiratory Distress Syndrome after Falciparum Malaria.

    Science.gov (United States)

    Harbarth; Meyer; Grau; Loutan; Ricou

    1997-09-01

    Incidence of falciparum malaria in developed countries has increased in recent years due to tourism to tropical countries and immigration from Asia and Africa. In Switzerland, about 250 cases of malaria were reported in 1994 to the Federal Office of Health, including three cases with fatal outcome.1 The most commonly described complications of plasmodia infection are cerebral malaria, acute renal failure, and severe anemia with disseminated intravascular coagulation. However, pulmonary involvement occurs in 3 to 10% of cases and represents the most serious complication of this infection, with a lethality of 70%.2,3 Furthermore, a pronounced general immunosuppression has been reported in malaria patients, which may predispose them to opportunistic infections.4 We report a case of Plasmodium falciparum infection complicated by severe acute respiratory distress syndrome (ARDS) with development of systemic cytomegalovirus (CMV) infection leading to death. This evolution implies a severe immune deficiency associated with malaria, as previously suggested in the literature.

  1. Expression of a type B RIFIN in Plasmodium falciparum merozoites and gametes

    DEFF Research Database (Denmark)

    Mwakalinga, Steven B; Wang, Christian W; Bengtsson, Dominique C

    2012-01-01

    ABSTRACT: BACKGROUND: The ability of Plasmodium falciparum to undergo antigenic variation, by switching expression among protein variants encoded by multigene families, such as var, rif and stevor, is key to the survival of this parasite in the human host. The RIFIN protein family can be divided...... into A and B types based on the presence or absence of a 25 amino acid motif in the semi-conserved domain. A particular type B RIFIN, PF13_0006, has previously been shown to be strongly transcribed in the asexual and sexual stages of P. falciparum in vitro. METHODS: Antibodies to recombinant PF13_0006 RIFIN...... were used in immunofluorescence and confocal imaging of 3D7 parasites throughout the asexual reproduction and sexual development to examine the expression of PF13_0006. Furthermore, reactivity to recombinant PF13_0006 was measured in plasma samples collected from individuals from both East and West...

  2. Plasmodium falciparum: assessment of in vitro growth by [3H]hypoxanthine incorporation

    International Nuclear Information System (INIS)

    Chulay, J.D.; Haynes, J.D.; Diggs, C.L.

    1983-01-01

    To evaluate rapidly Plasmodium falciparum growth in Vitro, [ 3 H]hypoxanthine was added to parasite microcultures and radioisotope incorporation was measured. When culture parameters were carefully controlled, [ 3 H]hypoxanthine incorporation was proportional to the number of parasitized erythrocytes present. Factors affecting [ 3 H]hypoxanthine incorporation included initial parasitemia, duration of culture, duration of radioisotope pulse, parasite stage, concentration of uninfected erythrocytes, the use of serum or plasma to supplement growth, and the concentration of a variety of purines in the culture medium. The method described can be used to measure inhibition of P. falciparum growth by immune serum and has previously been used to study antimalarial drug activity in vitro

  3. Structure of the conserved hypothetical protein MAL13P1.257 from Plasmodium falciparum

    International Nuclear Information System (INIS)

    Holmes, Margaret A.; Buckner, Frederick S.; Van Voorhis, Wesley C.; Mehlin, Christopher; Boni, Erica; Earnest, Thomas N.; DeTitta, George; Luft, Joseph; Lauricella, Angela; Anderson, Lori; Kalyuzhniy, Oleksandr; Zucker, Frank; Schoenfeld, Lori W.; Hol, Wim G. J.; Merritt, Ethan A.

    2006-01-01

    The crystal structure of a conserved hypothetical protein, MAL13P1.257 from P. falciparum, has been determined at 2.17 Å resolution. The structure represents a new protein fold and is the first structural representative for Pfam sequence family PF05907. The structure of a conserved hypothetical protein, PlasmoDB sequence MAL13P1.257 from Plasmodium falciparum, Pfam sequence family PF05907, has been determined as part of the structural genomics effort of the Structural Genomics of Pathogenic Protozoa consortium. The structure was determined by multiple-wavelength anomalous dispersion at 2.17 Å resolution. The structure is almost entirely β-sheet; it consists of 15 β-strands and one short 3 10 -helix and represents a new protein fold. The packing of the two monomers in the asymmetric unit indicates that the biological unit may be a dimer.

  4. Role of Chromatin assembly factor 1 in DNA replication of Plasmodium falciparum.

    Science.gov (United States)

    Gupta, Mohit Kumar; Agarawal, Meetu; Banu, Khadija; Reddy, K Sony; Gaur, Deepak; Dhar, Suman Kumar

    2018-01-01

    Nucleosome assembly in P. falciparum could be the key process in maintaining its genomic integrity as DNA replicates more than once per cell cycle during several stages of its life cycle. Here, we report the functional characterization of P. falciparum chromatin assembly factor 1 (CAF1), which interacts with several proteins namely PfCAF2, Histones, PfHP1 and others. Consistent with the above findings, we demonstrate the presence of PfCAF1 at the telomeric repeat regions, central and subtelomeric var genes of multiple var gene family along with PfHP1. Further, we report the upregulation of PfCAF1 after treatment with genotoxic agents like MMS and HU. Together, these findings establish role of PfCAF1 in heterochromatin maintenance and as histone chaperone in nucleosome assembly and DNA damage repair. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Investigating the activity of quinine analogues versus chloroquine resistant Plasmodium falciparum.

    Science.gov (United States)

    Dinio, Theresa; Gorka, Alexander P; McGinniss, Andrew; Roepe, Paul D; Morgan, Jeremy B

    2012-05-15

    Plasmodium falciparum, the deadliest malarial parasite species, has developed resistance against nearly all man-made antimalarial drugs within the past century. However, quinine (QN), the first antimalarial drug, remains efficacious worldwide. Some chloroquine resistant (CQR) P. falciparum strains or isolates show mild cross resistance to QN, but many do not. Further optimization of QN may provide a well-tolerated therapy with improved activity versus CQR malaria. Thus, using the Heck reaction, we have pursued a structure-activity relationship study, including vinyl group modifications of QN. Certain derivatives show good antiplasmodial activity in QN-resistant and QN-sensitive strains, with lower IC(50) values relative to QN. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. The anthraquinone emodin inhibits the non-exported FIKK kinase from Plasmodium falciparum.

    Science.gov (United States)

    Lin, Benjamin C; Harris, Darcy R; Kirkman, Lucy M D; Perez, Astrid M; Qian, Yiwen; Schermerhorn, Janse T; Hong, Min Y; Winston, Dennis S; Xu, Lingyin; Lieber, Alexander M; Hamilton, Matthew; Brandt, Gabriel S

    2017-12-01

    The FIKK family of kinases is unique to parasites of the Apicomplexan order, which includes all malaria parasites. Plasmodium falciparum, the most virulent form of human malaria, has a family of 19 FIKK kinases, most of which are exported into the host red blood cell during malaria infection. Here, we confirm that FIKK 8 is a non-exported member of the FIKK kinase family. Through expression and purification of the recombinant kinase domain, we establish that emodin is a relatively high-affinity (IC 50 =2μM) inhibitor of PfFk8. Closely related anthraquinones do not inhibit PfFk8, suggesting that the particular substitution pattern of emodin is critical to the inhibitory pharmacophore. This first report of a P. falciparum FIKK kinase inhibitor lays the groundwork for developing specific inhibitors of the various members of the FIKK kinase family in order to probe their physiological function. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Mosquito Passage Dramatically Changes var Gene Expression in Controlled Human Plasmodium falciparum Infections.

    Science.gov (United States)

    Bachmann, Anna; Petter, Michaela; Krumkamp, Ralf; Esen, Meral; Held, Jana; Scholz, Judith A M; Li, Tao; Sim, B Kim Lee; Hoffman, Stephen L; Kremsner, Peter G; Mordmüller, Benjamin; Duffy, Michael F; Tannich, Egbert

    2016-04-01

    Virulence of the most deadly malaria parasite Plasmodium falciparum is linked to the variant surface antigen PfEMP1, which is encoded by about 60 var genes per parasite genome. Although the expression of particular variants has been associated with different clinical outcomes, little is known about var gene expression at the onset of infection. By analyzing controlled human malaria infections via quantitative real-time PCR, we show that parasite populations from 18 volunteers expressed virtually identical transcript patterns that were dominated by the subtelomeric var gene group B and, to a lesser extent, group A. Furthermore, major changes in composition and frequency of var gene transcripts were detected between the parental parasite culture that was used to infect mosquitoes and Plasmodia recovered from infected volunteers, suggesting that P. falciparum resets its var gene expression during mosquito passage and starts with the broad expression of a specific subset of var genes when entering the human blood phase.

  8. Increased eosinophil activity in acute Plasmodium falciparum infection - association with cerebral malaria

    DEFF Research Database (Denmark)

    Kurtzhals, J A; Reimert, C M; Tette, E

    1998-01-01

    To assess the eosinophil response to Plasmodium falciparum infection a cohort of initially parasite-free Ghanaian children was followed for 3 months. Seven of nine children who acquired an asymptomatic P. falciparum infection showed increase in eosinophil counts, while a decrease was found in seven...... of nine children with symptomatic malaria, and no change was observed in 14 children who remained parasite-free. In a hospital-based study, paediatric patients with cerebral malaria (CM), severe anaemia (SA), or uncomplicated malaria (UM) had uniformly low eosinophil counts during the acute illness...... followed by eosinophilia 30 days after cure. Plasma levels of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) were measured as indicators of eosinophil activation. In spite of the low eosinophil counts, ECP levels were increased on day 0 and significantly higher in patients with CM...

  9. PfSETvs methylation of histone H3K36 represses virulence genes in Plasmodium falciparum

    DEFF Research Database (Denmark)

    Jiang, Lubin; Mu, Jianbing; Zhang, Qingfeng

    2013-01-01

    The variant antigen Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), which is expressed on the surface of P. falciparum-infected red blood cells, is a critical virulence factor for malaria. Each parasite has 60 antigenically distinct var genes that each code for a different PfEMP1...... parasite nuclei and their expression as proteins on the surface of individual infected red blood cells. PfSETvs-dependent H3K36me3 is present along the entire gene body, including the transcription start site, to silence var genes. With low occupancy of PfSETvs at both the transcription start site of var...... protein. During infection the clonal parasite population expresses only one gene at a time before switching to the expression of a new variant antigen as an immune-evasion mechanism to avoid the host antibody response. The mechanism by which 59 of the 60 var genes are silenced remains largely unknown...

  10. Global mass spectrometry based metabolomics profiling of erythrocytes infected with Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Theodore R Sana

    Full Text Available Malaria is a global infectious disease that threatens the lives of millions of people. Transcriptomics, proteomics and functional genomics studies, as well as sequencing of the Plasmodium falciparum and Homo sapiens genomes, have shed new light on this host-parasite relationship. Recent advances in accurate mass measurement mass spectrometry, sophisticated data analysis software, and availability of biological pathway databases, have converged to facilitate our global, untargeted biochemical profiling study of in vitro P. falciparum-infected (IRBC and uninfected (NRBC erythrocytes. In order to expand the number of detectable metabolites, several key analytical steps in our workflows were optimized. Untargeted and targeted data mining resulted in detection of over one thousand features or chemical entities. Untargeted features were annotated via matching to the METLIN metabolite database. For targeted data mining, we queried the data using a compound database derived from a metabolic reconstruction of the P. falciparum genome. In total, over one hundred and fifty differential annotated metabolites were observed. To corroborate the representation of known biochemical pathways from our data, an inferential pathway analysis strategy was used to map annotated metabolites onto the BioCyc pathway collection. This hypothesis-generating approach resulted in over-representation of many metabolites onto several IRBC pathways, most prominently glycolysis. In addition, components of the "branched" TCA cycle, partial urea cycle, and nucleotide, amino acid, chorismate, sphingolipid and fatty acid metabolism were found to be altered in IRBCs. Interestingly, we detected and confirmed elevated levels for cyclic ADP ribose and phosphoribosyl AMP in IRBCs, a novel observation. These metabolites may play a role in regulating the release of intracellular Ca(2+ during P. falciparum infection. Our results support a strategy of global metabolite profiling by untargeted

  11. Analysis of Plasmodium falciparum diversity in natural infections by deep sequencing

    OpenAIRE

    Manske, Magnus; Miotto, Olivo; Campino, Susana; Auburn, Sarah; Almagro-Garcia, Jacob; Maslen, Gareth; O?Brien, Jack; Djimde, Abdoulaye; Doumbo, Ogobara; Zongo, Issaka; Ouedraogo, Jean-Bosco; Michon, Pascal; Mueller, Ivo; Siba, Peter; Nzila, Alexis

    2012-01-01

    : Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. Here we describe methods for the large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short-term culture. Analysis of 86,158 exonic single nucleotide polymorphisms that passed genotyping quality c...

  12. Antimalarial drug targets in Plasmodium falciparum predicted by stage-specific metabolic network analysis

    OpenAIRE

    Huthmacher, Carola; Hoppe, Andreas; Bulik, Sascha; Holzh?tter, Hermann-Georg

    2010-01-01

    Abstract Background Despite enormous efforts to combat malaria the disease still afflicts up to half a billion people each year of which more than one million die. Currently no approved vaccine is available and resistances to antimalarials are widely spread. Hence, new antimalarial drugs are urgently needed. Results Here, we present a computational analysis of the metabolism of Plasmodium falciparum, the deadliest malaria pathogen. We assembled a compartmentalized metabolic model and predicte...

  13. Impact of child malnutrition on the specific anti-Plasmodium falciparum antibody response

    Directory of Open Access Journals (Sweden)

    Fillol Florie

    2009-06-01

    Full Text Available Abstract Background In sub-Saharan Africa, preschool children represent the population most vulnerable to malaria and malnutrition. It is widely recognized that malnutrition compromises the immune function, resulting in higher risk of infection. However, very few studies have investigated the relationship between malaria, malnutrition and specific immunity. In the present study, the anti-Plasmodium falciparum IgG antibody (Ab response was evaluated in children according to the type of malnutrition. Methods Anthropometric assessment and blood sample collection were carried out during a cross-sectional survey including rural Senegalese preschool children. This cross-sectional survey was conducted in July 2003 at the onset of the rainy season. Malnutrition was defined as stunting (height-for-age P. falciparum whole extracts (schizont antigens was assessed by ELISA in sera of the included children. Results Both the prevalence of anti-malarial immune responders and specific IgG Ab levels were significantly lower in malnourished children than in controls. Depending on the type of malnutrition, wasted children and stunted children presented a lower specific IgG Ab response than their respective controls, but this difference was significant only in stunted children (P = 0.026. This down-regulation of the specific Ab response seemed to be explained by severely stunted children (HAZ ≤ -2.5 compared to their controls (P = 0.03, while no significant difference was observed in mildly stunted children (-2.5 P. falciparum Ab response appeared to be independent of the intensity of infection. Conclusion Child malnutrition, and particularly stunting, may down-regulate the anti-P. falciparum Ab response, both in terms of prevalence of immune responders and specific IgG Ab levels. This study provides further evidence for the influence of malnutrition on the specific anti-malarial immune response and points to the importance of taking into account child

  14. The role of Plasmodium falciparum variant surface antigens in protective immunity and vaccine development

    DEFF Research Database (Denmark)

    Hviid, Lars

    2010-01-01

    There is substantial immuno-epidemiological evidence that the parasite-encoded, so-called variant surface antigens (VSAs) such as PfEMP1 on the surface of infected erythrocytes (IEs) are important-in some cases probably decisive-determinants of clinical outcome of P. falciparum malaria. The evide...... of VSAs, and how vaccines based on this type of antigens fit into the current global strategy to reduce, eliminate and eventually eradicate the burden of malaria....

  15. Pantothenamides are potent, on-target inhibitors of Plasmodium falciparum growth when serum pantetheinase is inactivated.

    Directory of Open Access Journals (Sweden)

    Christina Spry

    Full Text Available Growth of the virulent human malaria parasite Plasmodium falciparum is dependent on an extracellular supply of pantothenate (vitamin B(5 and is susceptible to inhibition by pantothenate analogues that hinder pantothenate utilization. In this study, on the hunt for pantothenate analogues with increased potency relative to those reported previously, we screened a series of pantothenamides (amide analogues of pantothenate against P. falciparum and show for the first time that analogues of this type possess antiplasmodial activity. Although the active pantothenamides in this series exhibit only modest potency under standard in vitro culture conditions, we show that the potency of pantothenamides is selectively enhanced when the parasite culture medium is pre-incubated at 37°C for a prolonged period. We present evidence that this finding is linked to the presence in Albumax II (a serum-substitute routinely used for in vitro cultivation of P. falciparum of pantetheinase activity: the activity of an enzyme that hydrolyzes the pantothenate metabolite pantetheine, for which pantothenamides also serve as substrates. Pantetheinase activity, and thereby pantothenamide degradation, is reduced following incubation of Albumax II-containing culture medium for a prolonged period at 37°C, revealing the true, sub-micromolar potency of pantothenamides. Importantly we show that the potent antiplasmodial effect of pantothenamides is attenuated with pantothenate, consistent with the compounds inhibiting parasite proliferation specifically by inhibiting pantothenate and/or CoA utilization. Additionally, we show that the pantothenamides interact with P. falciparum pantothenate kinase, the first enzyme involved in converting pantothenate to coenzyme A. This is the first demonstration of on-target antiplasmodial pantothenate analogues with sub-micromolar potency, and highlights the potential of pantetheinase-resistant pantothenamides as antimalarial agents.

  16. Malarone treatment failure and in vitro confirmation of resistance of Plasmodium falciparum isolate from Lagos, Nigeria

    OpenAIRE

    Fivelman, Quinton L; Butcher, Geoffrey A; Adagu, Ipemida S; Warhurst, David C; Pasvol, Geoffrey

    2002-01-01

    Abstract We report the first in vitro and genetic confirmation of Malarone® (GlaxoSmithKline; atovaquone and proguanil hydrochloride) resistance in Plasmodium falciparum acquired in Africa. On presenting with malaria two weeks after returning from a 4-week visit to Lagos, Nigeria without prophylaxis, a male patient was given a standard 3-day treatment course of Malarone®. Twenty-eight days later the parasitaemia recrudesced. Parasites were cultured from the blood and the isolate (NGATV01) was...

  17. Bioinformatics analysis for structure and function of CPR of Plasmodium falciparum.

    Science.gov (United States)

    Fan, Zhigang; Zhang, Lingmin; Yan, Guogang; Wu, Qiang; Gan, Xiufeng; Zhong, Saifeng; Lin, Guifen

    2011-02-01

    To analyse the structure and function of NADPH-cytochrome p450 reductase (CYPOR or CPR) from Plasmodium falciparum (Pf), and to predict its' drug target and vaccine target. The structure, function, drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods. PfCPR, which was older CPR, had close relationship with the CPR from other Plasmodium species, but it was distant from its hosts, such as Homo sapiens and Anopheles. PfCPR was located in the cellular nucleus of Plasmodium falciparum. 335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane, while 151aa-265aa was located in the nucleolus organizer regions. PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence. The teriary structure of 1aa-700aa was forcep-shaped with wings. 15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein. These segments had 25 protein-protein binding sites. While 13 other segments all possessed function sites. The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens. PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes. PfCPR is unsuitable as vaccine target, but it has at least 13 ideal drug targets. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  18. P. falciparum malaria prevalence among blood donors in Bamako, Mali.

    Science.gov (United States)

    Kouriba, B; Diarra, A B; Douyon, I; Diabaté, D T; Kamissoko, F; Guitteye, H; Baby, M; Guindo, M A; Doumbo, O K

    2017-06-01

    Malaria parasite is usually transmitted to humans by Anopheles mosquitoes but it can also be transmitted through blood transfusion. Usually malaria transmission is low in African urban settings. In West Africa where the P. falciparum is the most predominant malaria species, there are limited measures to reduce the risk of blood transfusion malaria. The aim of this study was to evaluate the prevalence of P. falciparum malaria carriage among blood donors in the National Blood Center of Bamako, capital city of Mali. The study was conducted using a random sample of 946 blood donors in Bamako, Mali, from January to December 2011. Screening for malaria was performed by thick smear and rapid diagnostic test (RDT). Blood group was typed by Beth-Vincent and Simonin techniques. The frequency of malaria infection was 1.4% by thick smear and 0.8% by the RDT. The pick prevalence of P. falciparum malaria was in rainy season, indicating a probable high seasonal risk of malaria by blood transfusion, in Mali. The prevalence of P. falciparum infection was 2% among donors of group O the majority being in this group. There is a seasonal prevalence of malaria among blood donors in Bamako. A prevention strategy of transfusion malaria based on the combination of selection of blood donors through the medical interview, promoting a voluntary low-risk blood donation and screening all blood bags intended to be transfused to children under 5, pregnant women and immune-compromised patients during transmission season using thick smear will reduce the risk of transfusion malaria in Mali. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  19. Cytoadhesion of Plasmodium falciparum-infected erythrocytes and the infected placenta: a two-way pathway

    Directory of Open Access Journals (Sweden)

    F.T.M. Costa

    2006-12-01

    Full Text Available Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM. This specific maternal-fetal syndrome causes maternal anemia, low birth weight and the death of 62,000 to 363,000 infants per year in sub-Saharan Africa, and thus has a poor outcome for both mother and fetus. However, PAM and non-PAM parasites have been shown to differ antigenically and genetically. After multiple pregnancies, women from different geographical areas develop adhesion-blocking antibodies that protect against placental parasitemia and clinical symptoms of PAM. The recent description of a new parasite ligand encoded by the var2CSA gene as the only gene up-regulated in PAM parasites renders the development of an anti-PAM vaccine more feasible. The search for a vaccine to prevent P. falciparum sequestration in the placenta by eliciting adhesion-blocking antibodies and a cellular immune response, and the development of new methods for evaluating such antibodies should be key priorities in mother-child health programs in areas of endemic malaria. This review summarizes the main molecular, immunological and physiopathological aspects of PAM, including findings related to new targets in the P. falciparum var gene family. Finally, we focus on a new methodology for mimicking cytoadhesion under blood flow conditions in human placental tissue.

  20. Multiple essential functions of Plasmodium falciparum actin-1 during malaria blood-stage development.

    Science.gov (United States)

    Das, Sujaan; Lemgruber, Leandro; Tay, Chwen L; Baum, Jake; Meissner, Markus

    2017-08-15

    The phylum Apicomplexa includes intracellular parasites causing immense global disease burden, the deadliest of them being the human malaria parasite Plasmodium falciparum, which invades and replicates within erythrocytes. The cytoskeletal protein actin is well conserved within apicomplexans but divergent from mammalian actins, and was primarily reported to function during host cell invasion. However, novel invasion mechanisms have been described for several apicomplexans, and specific functions of the acto-myosin system are being reinvestigated. Of the two actin genes in P. falciparum, actin-1 (pfact1) is ubiquitously expressed in all life-cycle stages and is thought to be required for erythrocyte invasion, although its functions during parasite development are unknown, and definitive in vivo characterisation during invasion is lacking. Here we have used a conditional Cre-lox system to investigate the functions of PfACT1 during P. falciparum blood-stage development and host cell invasion. We demonstrate that PfACT1 is crucially required for segregation of the plastid-like organelle, the apicoplast, and for efficient daughter cell separation during the final stages of cytokinesis. Surprisingly, we observe that egress from the host cell is not an actin-dependent process. Finally, we show that parasites lacking PfACT1 are capable of microneme secretion, attachment and formation of a junction with the erythrocyte, but are incapable of host cell invasion. This study provides important mechanistic insights into the definitive essential functions of PfACT1 in P. falciparum, which are not only of biological interest, but owing to functional divergence from mammalian actins, could also form the basis for the development of novel therapeutics against apicomplexans.