scholarly journals Molecular Characterization of the CytochromebGene andIn VitroAtovaquone Susceptibility of Plasmodium falciparum Isolates from Kenya

2015 ◽  
Vol 59 (3) ◽  
pp. 1818-1821 ◽  
Author(s):  
Luicer A. Ingasia ◽  
Hoseah M. Akala ◽  
Mabel O. Imbuga ◽  
Benjamin H. Opot ◽  
Fredrick L. Eyase ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Polymorphism ◽  
Molecular Characterization ◽  
Mutant Allele ◽  
Inhibitory Concentration ◽  
Wild Type Allele ◽  
Wild Type ◽  
Western Kenya ◽  
Content Type

ABSTRACTThe prevalence of a genetic polymorphism(s) at codon 268 in the cytochromebgene, which is associated with failure of atovaquone-proguanil treatment, was analyzed in 227Plasmodium falciparumparasites from western Kenya. The prevalence of the wild-type allele was 63%, and that of the Y268S (denoting a Y-to-S change at position 268) mutant allele was 2%. There were no pure Y268C or Y268N mutant alleles, only mixtures of a mutant allele(s) with the wild type. There was a correlation between parasite 50% inhibitory concentration (IC50) and parasite genetic polymorphism; mutant alleles had higher IC50s than the wild type.

scholarly journals In Vitroand Molecular Surveillance for Antimalarial Drug Resistance in Plasmodium falciparum Parasites in Western Kenya Reveals Sustained Artemisinin Sensitivity and Increased Chloroquine Sensitivity

2015 ◽  
Vol 59 (12) ◽  
pp. 7540-7547 ◽  
Author(s):  
Naomi W. Lucchi ◽  
Franklin Komino ◽  
Sheila Akinyi Okoth ◽  
Ira Goldman ◽  
Philip Onyona ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Antimalarial Drug ◽  
Mutant Allele ◽  
Surveillance Program ◽  
Wild Type ◽  
Antimalarial Drug Resistance ◽  
Western Kenya ◽  
Content Type

ABSTRACTMalaria control is hindered by the evolution and spread of resistance to antimalarials, necessitating multiple changes to drug policies over time. A comprehensive antimalarial drug resistance surveillance program is vital for detecting the potential emergence of resistance to antimalarials, including current artemisinin-based combination therapies. An antimalarial drug resistance surveillance study involving 203Plasmodium falciparummalaria-positive children was conducted in western Kenya between 2010 and 2013. Specimens from enrolled children were analyzedin vitrofor sensitivity to chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ), lumefantrine, and artemisinin derivatives (artesunate and dihydroartemisinin) and for drug resistance allele polymorphisms inP. falciparum crt(Pfcrt),Pfmdr-1, and the K13 propeller domain (K13). We observed a significant increase in the proportion of samples with thePfcrtwild-type (CVMNK) genotype, from 61.2% in 2010 to 93.0% in 2013 (P< 0.0001), and higher proportions of parasites with elevated sensitivity to CQin vitro. The majority of isolates harbored the wild-type N allele inPfmdr-1codon 86 (93.5%), with only 7 (3.50%) samples with the N86Ymutant allele (the mutant nucleotide is underlined). Likewise, most isolates harbored the wild-typePfmdr-1D1246 allele (79.8%), with only 12 (6.38%) specimens with the D1246Ymutant allele and 26 (13.8%) with mixed alleles. All the samples had a single copy of thePfmdr-1gene (mean of 0.907 ± 0.141 copies). None of the sequenced parasites had mutations in K13. Our results suggest that artemisinin is likely to remain highly efficacious and that CQ sensitivity appears to be on the rise in western Kenya.

scholarly journals Reduced Polymorphism in the Kelch Propeller Domain in Plasmodium vivax Isolates from Cambodia

2014 ◽  
Vol 59 (1) ◽  
pp. 730-733 ◽  
Author(s):  
Jean Popovici ◽  
Sokheng Kao ◽  
Leanghor Eal ◽  
Sophalai Bin ◽  
Saorin Kim ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Preliminary Data ◽  
Mutant Allele ◽  
Chloroquine Resistance ◽  
Wild Type ◽  
Nonsynonymous Mutation ◽  
Content Type

ABSTRACTPolymorphism in the ortholog gene of thePlasmodium falciparumK13 gene was investigated inPlasmodium vivaxisolates collected in Cambodia. All of them were Sal-1 wild-type alleles except two (2/284, 0.7%), andP. vivaxK12 polymorphism was reduced compared to that of theP. falciparumK13 gene. Both mutant allele isolates had the same nonsynonymous mutation at codon 552 (V552I) and were from Ratanak Kiri province. These preliminary data should encourage additional studies for associating artemisinin or chloroquine resistance and K12 polymorphism.

scholarly journals Increasing Prevalence of a Novel Triple-Mutant Dihydropteroate Synthase Genotype in Plasmodium falciparum in Western Kenya

2015 ◽  
Vol 59 (7) ◽  
pp. 3995-4002 ◽  
Author(s):  
Naomi W. Lucchi ◽  
Sheila Akinyi Okoth ◽  
Franklin Komino ◽  
Philip Onyona ◽  
Ira F. Goldman ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Mutant Allele ◽  
Double Mutant ◽  
Intermittent Preventive Treatment ◽  
Preventive Treatment ◽  
Triple Mutant ◽  
Western Kenya ◽  
Content Type ◽  
Dihydropteroate Synthase

ABSTRACTThe molecular basis of sulfadoxine-pyrimethamine (SP) resistance lies in a combination of single-nucleotide polymorphisms (SNPs) in two genes coding forPlasmodium falciparumdihydrofolate reductase (Pfdhfr) andP. falciparumdihydropteroate synthase (Pfdhps), targeted by pyrimethamine and sulfadoxine, respectively. The continued use of SP for intermittent preventive treatment in pregnant women in many African countries, despite SP's discontinuation as a first-line antimalarial treatment option due to high levels of drug resistance, may further increase the prevalence of SP-resistant parasites and/or lead to the selection of new mutations. An antimalarial drug resistance surveillance study was conducted in western Kenya between 2010 and 2013. A total of 203 clinical samples from children with uncomplicated malaria were genotyped for SNPs associated with SP resistance. The prevalence of the triple-mutantPfdhfrC50I51R59N108I164genotype and the double-mutantPfdhpsS436G437E540A581A613genotype was high. Two triple-mutantPfdhpsgenotypes, S436G437E540G581A613andH436G437E540A581A613, were found, with the latter thus far being uniquely found in western Kenya. The prevalence of the S436G437E540G581A613genotype was low. However, a steady increase in the prevalence of thePfdhpstriple-mutantH436G437E540A581A613genotype has been observed since its appearance in early 2000. Isolates with these genotypes shared substantial microsatellite haplotypes with the most common double-mutant allele, suggesting that this triple-mutant allele may have evolved locally. Overall, these findings show that the prevalence of theH436G437E540A581A613triple mutant may be increasing in this population and could compromise the efficacy of SP for intermittent preventive treatment in pregnant women if it increases the resistance threshold further.

scholarly journals Sulfur Mobilization for Fe-S Cluster Assembly by the Essential SUF Pathway in the Plasmodium falciparum Apicoplast and Its Inhibition

2014 ◽  
Vol 58 (6) ◽  
pp. 3389-3398 ◽  
Author(s):  
Manish Charan ◽  
Nidhi Singh ◽  
Bijay Kumar ◽  
Kumkum Srivastava ◽  
Mohammad Imran Siddiqi ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Pyridoxal Phosphate ◽  
Inhibitory Concentration ◽  
Cluster Assembly ◽  
Cysteine Desulfurase ◽  
Content Type ◽  
Biochemical Investigation ◽  
Parasite Survival

ABSTRACTThe plastid of the malaria parasite, the apicoplast, is essential for parasite survival. It houses several pathways of bacterial origin that are considered attractive sites for drug intervention. Among these is the sulfur mobilization (SUF) pathway of Fe-S cluster biogenesis. Although the SUF pathway is essential for apicoplast maintenance and parasite survival, there has been limited biochemical investigation of its components and inhibitors ofPlasmodiumSUFs have not been identified. We report the characterization of two proteins,Plasmodium falciparumSufS (PfSufS) andPfSufE, that mobilize sulfur in the first step of Fe-S cluster assembly and confirm their exclusive localization to the apicoplast. The cysteine desulfurase activity ofPfSufS is greatly enhanced byPfSufE, and thePfSufS-PfSufE complex is detectedin vivo. Structural modeling of the complex reveals proximal positioning of conserved cysteine residues of the two proteins that would allow sulfide transfer from the PLP (pyridoxal phosphate) cofactor-bound active site ofPfSufS. Sulfide release from thel-cysteine substrate catalyzed byPfSufS is inhibited by the PLP inhibitord-cycloserine, which forms an adduct withPfSufS-bound PLP.d-Cycloserine is also inimical to parasite growth, with a 50% inhibitory concentration close to that reported forMycobacterium tuberculosis, against which the drug is in clinical use. Our results establish the function of two proteins that mediate sulfur mobilization, the first step in the apicoplast SUF pathway, and provide a rationale for drug design based on inactivation of the PLP cofactor ofPfSufS.

scholarly journals Mutator-Suppressible Alleles of rough sheath1 and liguleless3 in Maize Reveal Multiple Mechanisms for Suppression

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 437-446 ◽  
Author(s):  
Lisa Girard ◽  
Michael Freeling
Keyword(s):  
Untranslated Region ◽  
Mutant Allele ◽  
Negative Regulation ◽  
Wild Type ◽  
Knox Gene ◽  
Transcript Accumulation ◽  
Mu Suppression ◽  
Different Types ◽  
Rna Blot Analysis

Abstract Insertions of Mutator transposons into maize genes can generate suppressible alleles. Mu suppression is when, in the absence of Mu activity, the phenotype of a mutant allele reverts to that of its progenitor. Here we present the characterization of five dominant Mu-suppressible alleles of the knox (knotted1-like homeobox) genes liguleless3 and rough sheath1, which exhibit neomorphic phenotypes in the leaves. RNA blot analysis suggests that Mu suppression affects only the neomorphic aspect of the allele, not the wild-type aspect. Additionally, Mu suppression appears to be exerting its effects at the level of transcription or transcript accumulation. We show that truncated transcripts are produced by three alleles, implying a mechanism for Mu suppression of 5′ untranslated region insertion alleles distinct from that which has been described previously. Additionally, it is found that Mu suppression can be caused by at least three different types of Mutator elements. Evidence presented here suggests that whether an allele is suppressible or not may depend upon the site of insertion. We cite previous work on the knox gene kn1, and discuss our results in the context of interactions between Mu-encoded products and the inherently negative regulation of neomorphic liguleless3 and rough sheath1 transcription.

scholarly journals Trans-splicing as a Novel Mechanism to Explain Interallelic Complementation in Drosophila

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1481-1487 ◽  
Author(s):  
Fabien Mongelard ◽  
Mariano Labrador ◽  
Ellen M Baxter ◽  
Tatiana I Gerasimova ◽  
Victor G Corces
Keyword(s):  
Molecular Characterization ◽  
Wild Type ◽  
Functional Protein ◽  
Gypsy Insulator ◽  
Type Function ◽  
Homologous Chromosomes ◽  
Trans Splicing ◽  
Interallelic Complementation

AbstractTwo mutant alleles of the same gene, each located in one of the two homologous chromosomes, may in some instances restore the wild-type function of the gene. This is the case with certain combinations of mutant alleles in the mod(mdg4) gene. This gene encodes several different proteins, including Mod(mdg4)2.2, a component of the gypsy insulator. This protein is encoded by two separate transcription units that can be combined in a trans-splicing reaction to form the mature Mod(mdg4)2.2-encoding RNA. Molecular characterization of complementing alleles shows that they affect the two different transcription units. Flies homozygous for each allele are missing the Mod(mdg4)2.2 protein, whereas wild-type trans-heterozygotes are able to synthesize almost normal levels of the Mod(mdg4)2.2 product. This protein is functional as judged by its ability to form a functional insulator complex. The results suggest that the interallelic complementation in the mod(mdg4) gene is a consequence of trans-splicing between two different mutant transcripts. A conclusion from this observation is that the trans-splicing reaction that takes place between transcripts produced on two different mutant chromosomes ensures wild-type levels of functional protein.

Molecular characterization of Plasmodium falciparum putative polynucleotide kinase/phosphatase

2011 ◽  
Vol 180 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Saranya Siribal ◽  
Michael Weinfeld ◽  
Feridoun Karimi-Busheri ◽  
J.N. Mark Glover ◽  
Nina K. Bernstein ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Characterization ◽  
Polynucleotide Kinase

scholarly journals Molecular Characterization of Human-Pathogenic Microsporidia and Cyclospora cayetanensis Isolated from Various Water Sources in Spain: a Year-Long Longitudinal Study

2012 ◽  
Vol 79 (2) ◽  
pp. 449-459 ◽  
Author(s):  
Ana Luz Galván ◽  
Angela Magnet ◽  
Fernando Izquierdo ◽  
Soledad Fenoy ◽  
Cristina Rueda ◽  
...  
Keyword(s):  
Drinking Water ◽  
Longitudinal Study ◽  
Water Treatment ◽  
Molecular Characterization ◽  
Drinking Water Treatment ◽  
Enterocytozoon Bieneusi ◽  
Content Type ◽  
Cyclospora Cayetanensis ◽  
Water Treatment Plants

ABSTRACTRecent studies suggest the involvement of water in the epidemiology ofCyclospora cayetanensisand some microsporidia. A total of 223 samples from four drinking water treatment plants (DWTPs), seven wastewater treatment plants (WWTPs), and six locations of influence (LI) on four river basins from Madrid, Spain, were analyzed from spring 2008 to winter 2009. Microsporidia were detected in 49% of samples (109/223),Cyclosporaspp. were detected in 9% (20/223), and both parasites were found in 5.4% (12/223) of samples. Human-pathogenic microsporidia were detected, includingEnterocytozoon bieneusi(C, D, and D-like genotypes),Encephalitozoon intestinalis,Encephalitozoon cuniculi(genotypes I and III), andAnncaliia algerae.C. cayetanensiswas identified in 17 of 20 samples. To our knowledge, this is the first study that shows a year-long longitudinal study ofC. cayetanensisin drinking water treatment plants. Additionally, data about the presence and molecular characterization of the human-pathogenic microsporidia in drinking water, wastewater, and locations of influence during 1 year in Spain are shown. It is noteworthy that although the DWTPs and WWTPs studied meet European and national regulations on water sanitary quality, both parasites were found in water samples from these plants, supporting the idea that new and appropriate controls and regulations for drinking water, wastewater, and recreational waters should be proposed to avoid health risks from these pathogens.

scholarly journals Characterization of Plasmodium falciparum NEDD8 and identification of cullins as its substrates

2020 ◽  
Author(s):  
Manish Bhattacharjee ◽  
Navin Adhikari ◽  
Renu Sudhakar ◽  
Zeba Rizvi ◽  
Divya Das ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Plasmodium Falciparum ◽  
Western Blot ◽  
Wild Type ◽  
Malaria Parasites ◽  
Post Translational Modifications ◽  
Functional Conservation ◽  
Cellular Processes ◽  
Physiological Substrates

ABSTRACTA variety of post-translational modifications of Plasmodium falciparum proteins, including phosphorylation and ubiquitination, are shown to have key regulatory roles. The neural precursor cell expressed developmentally downregulated protein 8 (NEDD8) is a ubiquitin-like modifier of cullin-RING E3 ubiquitin ligases, which regulate diverse cellular processes, including the cell-cycle. Although neddylation pathway is conserved in eukaryotes, it is yet to be characterized in Plasmodium and related apicomplexan parasites. Towards studying the neddylation pathway in malaria parasites, we characterized P. falciparum NEDD8 (PfNEDD8) and identified cullins as its physiological substrates. PfNEDD8 is a 76 amino acid residue protein without the C-terminal tail, indicating that it can be readily conjugated. The wild type and mutant (Gly75Gly76 mutated to Ala75Ala76) PfNEDD8 were expressed in P. falciparum. Western blot of wild type PfNEDD8-expressing parasites indicated multiple high molecular weight conjugates, which were absent in the parasites expressing the mutant, indicating conjugation of NEDD8 to proteins through Gly76. Immunoprecipitation followed by mass spectrometry of wild type PfNEDD8-expressing parasites identified several proteins, including two putative cullins. Furthermore, we expressed PfNEDD8 in mutant S. cerevisiae strains that lacked endogenous NEDD8 (Δrub1) or NEDD8 conjugating E2 enzyme (ΔUbc12). The western blot of complemented strains and mass spectrometry of PfNEDD8 immunoprecipitate showed conjugation of PfNEDD8 to S. cerevisiae cullin cdc53, demonstrating functional conservation and cullins as the physiological substrates of PfNEDD8. The characterization of PfNEDD8 and identification of cullins as its substrates make ground for investigation of specific roles and drug target potential of neddylation pathway in malaria parasites.

scholarly journals Molecular Characterization of anEndozoicomonas-Like Organism Causing Infection in the King Scallop (Pecten maximusL.)

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Irene Cano ◽  
Ronny van Aerle ◽  
Stuart Ross ◽  
David W. Verner-Jeffreys ◽  
Richard K. Paley ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Molecular Characterization ◽  
Mass Mortality ◽  
Rrna Gene ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
The 16S Rrna Gene

ABSTRACTOne of the fastest growing fisheries in the UK is the king scallop (Pecten maximusL.), also currently rated as the second most valuable fishery. Mass mortality events in scallops have been reported worldwide, often with the causative agent(s) remaining uncharacterized. In May 2013 and 2014, two mass mortality events affecting king scallops were recorded in the Lyme Bay marine protected area (MPA) in Southwest England. Histopathological examination showed gill epithelial tissues infected with intracellular microcolonies (IMCs) of bacteria resemblingRickettsia-like organisms (RLOs), often with bacteria released in vascular spaces. Large colonies were associated with cellular and tissue disruption of the gills. Ultrastructural examination confirmed the intracellular location of these organisms in affected epithelial cells. The 16S rRNA gene sequences of the putative IMCs obtained from infected king scallop gill samples, collected from both mortality events, were identical and had a 99.4% identity to 16S rRNA gene sequences obtained from “CandidatusEndonucleobacter bathymodioli” and 95% withEndozoicomonasspecies.In situhybridization assays using 16S rRNA gene probes confirmed the presence of the sequenced IMC gene in the gill tissues. Additional DNA sequences of the bacterium were obtained using high-throughput (Illumina) sequencing, and bioinformatic analysis identified over 1,000 genes with high similarity to protein sequences fromEndozoicomonasspp. (ranging from 77 to 87% identity). Specific PCR assays were developed and applied to screen for the presence of IMC 16S rRNA gene sequences in king scallop gill tissues collected at the Lyme Bay MPA during 2015 and 2016. There was 100% prevalence of the IMCs in these gill tissues, and the 16S rRNA gene sequences identified were identical to the sequence found during the previous mortality event.IMPORTANCEMolluscan mass mortalities associated with IMCs have been reported worldwide for many years; however, apart from histological and ultrastructural characterization, characterization of the etiological agents is limited. In the present work, we provide detailed molecular characterization of anEndozoicomonas-like organism (ELO) associated with an important commercial scallop species.

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