Comparative 3D ultrastructure of Plasmodium falciparum gametocytes
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ABSTRACT:
SUBMITTER: Taco W.A. Kooij
PROVIDER: EMPIAR-12160 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:BackgroundUnderstanding the dynamics of gametocyte production in polyclonal Plasmodium falciparum infections requires a genotyping method that detects distinct gametocyte clones and estimates their relative frequencies. Here, a marker was identified and evaluated to genotype P. falciparum mature gametocytes using amplicon deep sequencing.MethodsA data set of polymorphic regions of the P. falciparum genome was mined to identify a gametocyte genotyping marker. To assess marker resolution, the number of unique haplotypes in the marker region was estimated from 95 Malawian P. falciparum whole genome sequences. Specificity of the marker for detection of mature gametocytes was evaluated using reverse transcription-polymerase chain reaction of RNA extracted from NF54 mature gametocytes and rings from a non-gametocyte-producing strain of P. falciparum. Amplicon deep sequencing was performed on experimental mixtures of mature gametocytes from two distinct parasite clones, as well as gametocyte-positive P. falciparum field isolates to evaluate the quantitative ability and determine the limit of detection of the genotyping approach.ResultsA 400 bp region of the pfs230 gene was identified as a gametocyte genotyping marker. A larger number of unique haplotypes was observed at the pfs230 marker (34) compared to the sera-2 (18) and ama-1 (14) markers in field isolates from Malawi. RNA and DNA genotyping accurately estimated gametocyte and total parasite clone frequencies when evaluating agreement between expected and observed haplotype frequencies in gametocyte mixtures, with concordance correlation coefficients of 0.97 [95% CI: 0.92-0.99] and 0.92 [95% CI: 0.83-0.97], respectively. The detection limit of the genotyping method for male gametocytes was 0.41 pfmget transcripts/µl [95% CI: 0.28-0.72] and for female gametocytes was 1.98 ccp4 transcripts/µl [95% CI: 1.35-3.68].ConclusionsA region of the pfs230 gene was identified as a marker to genotype P. falciparum gametocytes. Amplicon deep sequencing of this marker can be used to estimate the number and relative frequency of parasite clones among mature gametocytes within P. falciparum infections. This gametocyte genotyping marker will be an important tool for studies aimed at understanding dynamics of gametocyte production in polyclonal P. falciparum infections.
| S-EPMC10999092 | biostudies-literature
Project description:The sexual stages are vital phases in malaria parasite transmission and are the targets of various interventions such as transmission blocking vaccines. The molecular mechanisms underlying sexual development, however, remain poorly understood. We report mappping of a determinant previously linked to a male gametocyte development defect in the P. falciparum Dd2 parasite to an 82 kb region on chromosome 12. In order to find a critical gene in this region, we compared gene expression pattern in sexual stage of the parasite between Dd2 and its normal gametocyte-producing ancestor W2 clones. The region contains a sexual stage specific gene (pfmdv 1) that is expressed substantially at a lower level in the Dd2 than in W2 parasite. Disruption of pfmdv 1 results in a dramatic reduction in mature gametocytes, especially male gametocytes, with the majority of sexually committed parasites arrested at stage-I. The pfmdv-1 knockout parasites show an enlarged nucleus, often with separation of the inner and outer nuclear membranes and presence of multi-membrane vesicles in red blood cell cytoplasm. Mosquito infectivity of the knockout parasites is also greatly reduced, but not completely lost, suggesting presence of compensatory mechanisms in the sexual development pathways. Data include Day 8 gametocytes of male defective Dd2 and parental W2 clones of Plasmodium falciparum. The series includes three biological repeats. Keywords: repeat sample
2010-06-10 | E-GEOD-2265 | biostudies-arrayexpress
Project description:BackgroundThe sexual stages (gametocytes) of Plasmodium falciparum do not directly contribute to the pathology of malaria but are essential for transmission of the parasite from the human host to the mosquito. Mature gametocytes circulate in infected human blood for several days and their circulation time has been modelled mathematically from data of previous in vivo studies. This is the first time that longevity of gametocytes is studied experimentally in vitro.MethodsThe in vitro longevity of P. falciparum gametocytes of 1 clinical isolate and 2 laboratory strains was assessed by three different methods: microscopy, flow cytometry and reverse transcription quantitative real-time PCR (RT-qPCR). Additionally, the rate of gametocytogenesis of the used P. falciparum strains was compared.ResultsThe maximum in vitro lifespan of P. falciparum gametocytes reached almost 2 months (49 days by flow cytometry, 46 days by microscopy, and at least 52 days by RT-qPCR) from the starting day of gametocyte culture to death of last parasite in the tested strains with an average 50% survival rate of 6.5, 2.6 and 3.5 days, respectively. Peak gametocytaemia was observed on average 19 days after initiation of gametocyte culture followed by a steady decline due to natural decay of the parasites. The rate of gametocytogenesis was highest in the NF54 strain.ConclusionsPlasmodium falciparum mature gametocytes can survive up to 16-32 days (at least 14 days for mature male gametocytes) in vitro in absence of the influence of host factors. This confirms experimentally a previous modelling estimate that used molecular tools for gametocyte detection in treated patients. The survival time might reflect the time the parasite can be transmitted to the mosquito after clearance of asexual parasites. These results underline the importance of efficient transmission blocking agents in the fight against malaria.
| S-EPMC5553604 | biostudies-literature
Project description:Plasmodium falciparum gametocytes have unique morphology, metabolism, and protein expression profiles in their asexual stages of development. In addition to the striking changes in their appearance, a wide variety of "exo-membrane structures" are newly formed in the gametocyte stage. Little is known about their function, localization, or three-dimensional structural information, and only some structural data, typically two-dimensional, have been reported using conventional electron microscopy or fluorescence microscopy. For better visualization of intracellular organelle and exo-membrane structures, we previously established an unroofing technique to directly observe Maurer's clefts (MCs) in asexual parasitized erythrocytes by removing the top part of the cell's membrane followed by transmission electron microscopy. We found that MCs have numerous tethers connecting themselves to the host erythrocyte membrane skeletons. In this study, we investigated the intracellular structures of gametocytes using unroofing-TEM, Serial Block Face scanning electron microscopy, and fluorescence microscopy to unveil the exo-membrane structures in gametocytes. Our data showed "balloon/pouch"-like objects budding from the parasitophorous vacuole membrane (PVM) in gametocytes, and some balloons included multiple layers of other balloons. Furthermore, numerous bubbles appeared on the inner surface of the erythrocyte membrane or PVM; these were similar to MC-like membranes but were smaller than asexual MCs. Our study demonstrated P. falciparum reforms exo-membranes in erythrocytes to meet stage-specific biological activities during their sexual development.
| S-EPMC9441640 | biostudies-literature
Project description:The sexual stages are vital phases in malaria parasite transmission and are the targets of various interventions such as transmission blocking vaccines. The molecular mechanisms underlying sexual development, however, remain poorly understood. We report mappping of a determinant previously linked to a male gametocyte development defect in the P. falciparum Dd2 parasite to an 82 kb region on chromosome 12. In order to find a critical gene in this region, we compared gene expression pattern in sexual stage of the parasite between Dd2 and its normal gametocyte-producing ancestor W2 clones. The region contains a sexual stage specific gene (pfmdv 1) that is expressed substantially at a lower level in the Dd2 than in W2 parasite. Disruption of pfmdv 1 results in a dramatic reduction in mature gametocytes, especially male gametocytes, with the majority of sexually committed parasites arrested at stage-I. The pfmdv-1 knockout parasites show an enlarged nucleus, often with separation of the inner and outer nuclear membranes and presence of multi-membrane vesicles in red blood cell cytoplasm. Mosquito infectivity of the knockout parasites is also greatly reduced, but not completely lost, suggesting presence of compensatory mechanisms in the sexual development pathways. Data include Day 8 gametocytes of male defective Dd2 and parental W2 clones of Plasmodium falciparum. The series includes three biological repeats. Keywords: repeat sample
2005-05-01 | GSE2265 | GEO
Project description: Not available
| EMPIAR-10392 | biostudies-other
Project description:The recent decline in global malaria burden has stimulated efforts toward Plasmodium falciparum elimination. Understanding the biology of malaria transmission stages may provide opportunities to reduce or prevent onward transmission to mosquitoes. Immature P. falciparum transmission stages, termed stages I to IV gametocytes, sequester in human bone marrow before release into the circulation as mature stage V gametocytes. This process likely involves interactions between host receptors and potentially immunogenic adhesins on the infected red blood cell (iRBC) surface. Here, we developed a flow cytometry assay to examine immune recognition of live gametocytes of different developmental stages by naturally exposed Malawians. We identified strong antibody recognition of the earliest immature gametocyte-iRBCs (giRBCs) but not mature stage V giRBCs. Candidate surface antigens (n = 30), most of them shared between asexual- and gametocyte-iRBCs, were identified by mass spectrometry and mouse immunizations, as well as correlations between responses by protein microarray and flow cytometry. Naturally acquired responses to a subset of candidate antigens were associated with reduced asexual and gametocyte density, and plasma samples from malaria-infected individuals were able to induce immune clearance of giRBCs in vitro. Infected RBC surface expression of select candidate antigens was validated using specific antibodies, and genetic analysis revealed a subset with minimal variation across strains. Our data demonstrate that humoral immune responses to immature giRBCs and shared iRBC antigens are naturally acquired after malaria exposure. These humoral immune responses may have consequences for malaria transmission potential by clearing developing gametocytes, which could be leveraged for malaria intervention.
| S-EPMC6653583 | biostudies-literature
Project description:BackgroundThe protozoan malaria parasite Plasmodium falciparum has a complex life cycle during which it needs to differentiate into multiple morphologically distinct life forms. A key process for transmission of the disease is the development of male and female gametocytes in the human blood, yet the mechanisms determining sexual dimorphism in these haploid, genetically identical sexual precursor cells remain largely unknown. To understand the epigenetic program underlying the differentiation of male and female gametocytes, we separated the two sexual forms by flow cytometry and performed RNAseq as well as comprehensive ChIPseq profiling of several histone variants and modifications.ResultsWe show that in female gametocytes the chromatin landscape is globally remodelled with respect to genome-wide patterns and combinatorial usage of histone variants and histone modifications. We identified sex specific differences in heterochromatin distribution, implicating exported proteins and ncRNAs in sex determination. Specifically in female gametocytes, the histone variants H2A.Z/H2B.Z were highly enriched in H3K9me3-associated heterochromatin. H3K27ac occupancy correlated with stage-specific gene expression, but in contrast to asexual parasites this was unlinked to H3K4me3 co-occupancy at promoters in female gametocytes.ConclusionsCollectively, we defined novel combinatorial chromatin states differentially organising the genome in gametocytes and asexual parasites and unravelled fundamental, sex-specific differences in the epigenetic code. Our chromatin maps represent an important resource for future understanding of the mechanisms driving sexual differentiation in P. falciparum.
| S-EPMC10071754 | biostudies-literature
Project description:New techniques for obtaining electron microscopy data through the cell volume are being increasingly utilized to answer cell biologic questions. Here, we present a three-dimensional atlas of Plasmodium falciparum ultrastructure throughout parasite cell division. Multiple wild type schizonts at different stages of segmentation, or budding, were imaged and rendered, and the 3D structure of their organelles and daughter cells are shown. Our high-resolution volume electron microscopy both confirms previously described features in 3D and adds new layers to our understanding of Plasmodium nuclear division. Interestingly, we demonstrate asynchrony of the final nuclear division, a process that had previously been reported as synchronous. Use of volume electron microscopy techniques for biological imaging is gaining prominence, and there is much we can learn from applying them to answer questions about Plasmodium cell biology. We provide this resource to encourage readers to consider adding these techniques to their cell biology toolbox.
| S-EPMC7302870 | biostudies-literature
Project description:The gametocyte transcriptomes were generated in P.falciparum parasites of 3D7 strain after PfHP1 depletion aming to determin the transriptional profiles of sexual stages during the parasites gametocyte development.
2018-12-10 | GSE121505 | GEO