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1.
Nat Commun ; 10(1): 4041, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492901

RESUMO

Members of the Apicomplexa phylum, including Plasmodium and Toxoplasma, have two types of secretory organelles (micronemes and rhoptries) whose sequential release is essential for invasion and the intracellular lifestyle of these eukaryotes. During invasion, rhoptries inject an array of invasion and virulence factors into the cytoplasm of the host cell, but the molecular mechanism mediating rhoptry exocytosis is unknown. Here we identify a set of parasite specific proteins, termed rhoptry apical surface proteins (RASP) that cap the extremity of the rhoptry. Depletion of RASP2 results in loss of rhoptry secretion and completely blocks parasite invasion and therefore parasite proliferation in both Toxoplasma and Plasmodium. Recombinant RASP2 binds charged lipids and likely contributes to assembling the machinery that docks/primes the rhoptry to the plasma membrane prior to fusion. This study provides important mechanistic insight into a parasite specific exocytic pathway, essential for the establishment of infection.


Assuntos
Proteínas de Transporte/metabolismo , Organelas/metabolismo , Fosfolipídeos/metabolismo , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Toxoplasma/metabolismo , Animais , Proteínas de Transporte/genética , Linhagem Celular , Exocitose , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/parasitologia , Interações Hospedeiro-Parasita , Humanos , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Parasitos/metabolismo , Parasitos/ultraestrutura , Fosfolipídeos/química , Proteínas de Protozoários/genética
2.
PLoS Biol ; 17(5): e3000264, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31075098

RESUMO

Cyclic AMP (cAMP) is an important signalling molecule across evolution, but its role in malaria parasites is poorly understood. We have investigated the role of cAMP in asexual blood stage development of Plasmodium falciparum through conditional disruption of adenylyl cyclase beta (ACß) and its downstream effector, cAMP-dependent protein kinase (PKA). We show that both production of cAMP and activity of PKA are critical for erythrocyte invasion, whilst key developmental steps that precede invasion still take place in the absence of cAMP-dependent signalling. We also show that another parasite protein with putative cyclic nucleotide binding sites, Plasmodium falciparum EPAC (PfEpac), does not play an essential role in blood stages. We identify and quantify numerous sites, phosphorylation of which is dependent on cAMP signalling, and we provide mechanistic insight as to how cAMP-dependent phosphorylation of the cytoplasmic domain of the essential invasion adhesin apical membrane antigen 1 (AMA1) regulates erythrocyte invasion.


Assuntos
AMP Cíclico/metabolismo , Interações Hospedeiro-Parasita , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Parasitos/metabolismo , Transdução de Sinais , Adenilil Ciclases/metabolismo , Animais , Cálcio/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Humanos , Parasitos/enzimologia , Parasitos/crescimento & desenvolvimento , Parasitos/ultraestrutura , Fosfoproteínas/metabolismo , Fosforilação , Fosfosserina/metabolismo , Plasmodium falciparum/enzimologia , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/patogenicidade , Plasmodium falciparum/ultraestrutura , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo
3.
Micron ; 121: 90-98, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30981155

RESUMO

Tools for taking advantage of phase-contrast in transmission electron microscopy are of great interest for both biological and material sciences studies as shown by the recent use of phase plates and the development of holography. Nevertheless, these tools most often require highly qualified experts and access to advanced equipment that can only be considered after preliminary investigations. Here we propose to address this issue by the development of an ImageJ plugin that allow the retrieval of a phase image by simple numerical treatment applied to two defocused images. This treatment based on Tikhonov regularization requires the adjustment of a single parameter. Moreover, it is possible to use this approach on one-image. Although in that case the retrieved image gives only qualitative information, it is able to enhance the image contrast appropriately. This can be of interest for specimens producing low contrast images under the electron microscopes, such as some frozen hydrated biological samples or those sensible to electron radiation unsuitable for holographic studies.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Microscopia Eletrônica de Transmissão , Animais , Bactérias/ultraestrutura , Ouro/química , Nanopartículas Metálicas/química , Microscopia de Contraste de Fase , Parasitos/ultraestrutura
4.
BMC Evol Biol ; 18(1): 193, 2018 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-30547744

RESUMO

BACKGROUND: Obligate pollination mutualisms (OPMs) are specialized interactions in which female pollinators transport pollen between the male and female flowers of a single plant species and then lay eggs into those same flowers. The pollinator offspring hatch and feed upon some or all of the developing ovules pollinated by their mothers. Strong trait matching between plants and their pollinators in OPMs is expected to result in reciprocal partner specificity i.e., a single pollinator species using a single plant species and vice versa, and strict co-speciation. These issues have been studied extensively in figs and fig wasps, but little in the more recently discovered co-diversification of Epicephala moths and their Phyllanthaceae hosts. OPMs involving Epicephala moths are believed occur in approximately 500 species of Phyllanthaceae, making it the second largest OPM group after the Ficus radiation (> 750 species). In this study, we used a mixture of DNA barcoding, genital morphology and behavioral observations to determine the number of Epicephala moth species inhabiting the fruits of Breynia oblongifolia, their geographic distribution, pollinating behavior and phylogenetic relationships. RESULTS: We found that B. oblongifolia hosts two species of pollinator that co-occurred at all study sites, violating the assumption of reciprocal specificity. Male and female genital morphologies both differed considerably between the two moth species. In particular, females differed in the shape of their ovipositors, eggs and oviposition sites. Phylogenetic analyses indicated that the two Epicephala spp. on B. oblongifolia likely co-exist due to a host switch. In addition, we discovered that Breynia fruits are also often inhabited by a third moth, an undescribed species of Herpystis, which is a non-pollinating seed parasite. CONCLUSIONS: Our study reveals new complexity in interactions between Phyllantheae and Epicephala pollinators and highlights that host switching, co-speciation and non-pollinating seed parasites can shape species interactions in OPMs. Our finding that co-occurring Epicephala species have contrasting oviposition modes parallels other studies and suggests that such traits are important in Epicephala species coexistence.


Assuntos
Malpighiaceae/parasitologia , Parasitos/fisiologia , Polinização/fisiologia , Animais , Teorema de Bayes , Código de Barras de DNA Taxonômico , Feminino , Geografia , Masculino , Mariposas/anatomia & histologia , Mariposas/fisiologia , Mariposas/ultraestrutura , New South Wales , Ovário/citologia , Oviposição , Óvulo Vegetal/citologia , Parasitos/anatomia & histologia , Parasitos/ultraestrutura , Filogenia , Especificidade da Espécie
5.
Dis Aquat Organ ; 129(3): 215-238, 2018 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-30154282

RESUMO

We investigated the seasonal and interannual changes in diversity, abundance, and prevalence of chaetognaths and their parasites collected monthly during 1996-1998 in the Mexican Central Pacific. We tested the hypothesis of a positive relationship between abundance and species richness of chaetognaths and their parasites, and investigated the influence of the 1997-1998 El Niño event on this host-parasite interaction. Of the 9 chaetognath species collected in the present study, only 7 were found to be parasitized. Of 78154 chaetognath specimens collected, 790 were parasitized (1% prevalence) with at least 1 type of epibiont (cysts, perhaps protists) and 6 types of endoparasites: protists (apicomplexans, dinoflagellates, and ciliates), digeneans, cestodes, acanthocephalans, nematodes, and other unidentified endoparasites. Cysts, digeneans, and cestodes were the most abundant parasites. Mean intensity ranged from 1-4 endoparasites and from 1-21 epibionts host-1. Zonosagitta bedoti and Flaccisagitta enflata were the most abundant chaetognath species and had the highest parasite diversity. Mesosagitta minima and Parasagitta euneritica had the highest parasite prevalence (>2%). A 2-way cluster analysis defined sampling month groups as before, during, and after the 1997-1998 El Niño. The highest abundances of chaetognaths and parasites were associated with a high thermal stratification index, salinity, and mixed layer depth. We conclude that there is a positive, non-linear correlation between the abundance of chaetognaths and their parasites. Although El Niño decreased the abundance and diversity of chaetognaths throughout the time series, the abundance and diversity of their parasites were not significantly different among hydro-climatic periods, suggesting that host abundance must decrease orders of magnitude to influence host availability for parasites.


Assuntos
El Niño Oscilação Sul , Invertebrados/parasitologia , Parasitos/fisiologia , Animais , Biodiversidade , Análise por Conglomerados , Interações Hospedeiro-Parasita , México , Oceano Pacífico , Parasitos/classificação , Parasitos/ultraestrutura , Estações do Ano , Especificidade da Espécie , Fatores de Tempo
6.
Sci Rep ; 8(1): 10165, 2018 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-29976932

RESUMO

Plasmodium knowlesi, a zoonotic parasite causing severe-to-lethal malaria disease in humans, has only recently been adapted to continuous culture with human red blood cells (RBCs). In comparison with the most virulent human malaria, Plasmodium falciparum, there are, however, few cellular tools available to study its biology, in particular direct investigation of RBC invasion by blood-stage P. knowlesi merozoites. This leaves our current understanding of biological differences across pathogenic Plasmodium spp. incomplete. Here, we report a robust method for isolating viable and invasive P. knowlesi merozoites to high purity and yield. Using this approach, we present detailed comparative dissection of merozoite invasion (using a variety of microscopy platforms) and direct assessment of kinetic differences between knowlesi and falciparum merozoites. We go on to assess the inhibitory potential of molecules targeting discrete steps of invasion in either species via a quantitative invasion inhibition assay, identifying a class of polysulfonate polymer able to efficiently inhibit invasion in both, providing a foundation for pan-Plasmodium merozoite inhibitor development. Given the close evolutionary relationship between P. knowlesi and P. vivax, the second leading cause of malaria-related morbidity, this study paves the way for inter-specific dissection of invasion by all three major pathogenic malaria species.


Assuntos
Eritrócitos/patologia , Eritrócitos/parasitologia , Malária/parasitologia , Merozoítos/patogenicidade , Parasitos/patogenicidade , Plasmodium knowlesi/patogenicidade , Animais , Sobrevivência Celular , Eritrócitos/efeitos dos fármacos , Eritrócitos/ultraestrutura , Filtração , Humanos , Cinética , Merozoítos/isolamento & purificação , Merozoítos/ultraestrutura , Parasitos/efeitos dos fármacos , Parasitos/crescimento & desenvolvimento , Parasitos/ultraestrutura , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium knowlesi/efeitos dos fármacos , Plasmodium knowlesi/crescimento & desenvolvimento , Plasmodium knowlesi/ultraestrutura , Polímeros/farmacologia , Sulfonas/farmacologia
7.
Acta Parasitol ; 63(2): 287-298, 2018 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-29654686

RESUMO

Balantioides coli is a ciliated protozoon that inhabits the intestine of pigs, non-human primates and humans. Light microscopy studies have described over 50 species of the genus Balantioides but their validity is in doubt. Due to the limited information about this genus, this study is aimed to identify morphological characteristics of Balantioides coli isolated using fluorescence microscopy and both scanning (SEM) and transmission electron microscopy (TEM). Trophozoites isolated from the feces of pig and macaque were washed and subjected to centrifugation. These cells were fixed with paraformaldehyde for immunofluorescence. Other aliquots of these trophozoites were fixed with glutaraldehyde, post fixed with osmium tetroxide and processed for SEM and TEM. Immunofluorescence studies revealed microtubules with a longitudinal distribution to the main axis of the parasite and in the constitution of cilia. SEM demonstrated a high concentration of cilia covering the oral apparatus and a poor presence of such structures in cytopyge. TEM revealed in the plasma membrane, several associated structures were observed to delineate the cellular cortex and mucocysts. The cytoskeleton of the oral region was observed in detail and had an organization pattern consisting of microtubules, which formed files and nematodesmal networks. Organelles such as hydrogenosomes like and peroxisomes were observed close to the cortex. Macronuclei were observed, but structures that were consistent with micronuclei were not identified. Ultrastructural morphological analysis of isolates confirms its similarity to Balantioides coli. In this study were identified structures that had not yet been described, such as hydrogenosomes like and cytoskeletal structures.


Assuntos
Parasitos/anatomia & histologia , Parasitos/ultraestrutura , Primatas/parasitologia , Suínos/parasitologia , Trofozoítos/ultraestrutura , Animais , Membrana Celular/ultraestrutura , Fezes/parasitologia , Humanos , Intestinos/parasitologia , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Microtúbulos/ultraestrutura , Organelas/ultraestrutura , Parasitos/isolamento & purificação , Peroxissomos/ultraestrutura , Infecções Protozoárias em Animais/parasitologia , Trofozoítos/isolamento & purificação
8.
Parasitol Int ; 67(4): 362-365, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29499324

RESUMO

The Somuncurá Plateau is a Protected Natural Area located in the middle of the northern extra-Andean arid Patagonia. Inhabited by at least 20 small mammal species, is the place with the uppermost species richness in Patagonia. The aim of this study was to examine the parasite remains from micromammal coprolites collected in association with a bone sequence recovered at the east of the Somuncurá Plateau (site "Alero Las Lechuzas"). Coprolites came from the four temporal units previously defined: unit I (4790 ±â€¯100 yrs. 14C B.P.), unit II, unit III (7840 ±â€¯120 yrs. 14C B.P.) and unit IV. Each coprolite was processed, rehydrated, homogenized, processed by spontaneous sedimentation and examined using a light microscope. Coprolites and eggs were described, measured and photographed. Samples were positive for two nematode species: Helminthoxys caudatus Freitas, Lent & Almeida, 1937 (Oxyurida, Oxyuridae) and Trichuris spp. (Trichinellida: Trichuridae). This is the first paleoparasitological study developed for the Somuncurá Plateau Protected Area. Moreover, this is the first time that the genus Helminthoxys is reported from ancient times worldwide. Coprolites were attributed to the mountain cavy Microcavia australis (Rodentia, Caviidae).The presence of H. caudatus for the Middle Holocene of northern Patagonia contributes to the study of the history of the histricomorphs and pinworms relationships.


Assuntos
Paleopatologia , Parasitos/isolamento & purificação , Roedores/parasitologia , Animais , Argentina , Fezes/parasitologia , Fósseis , Cobaias , Nematoides/isolamento & purificação , Óvulo/ultraestrutura , Oxyuroidea/isolamento & purificação , Parasitos/classificação , Parasitos/ultraestrutura , Trichuris/isolamento & purificação , Trichuris/ultraestrutura
9.
FEMS Microbiol Rev ; 41(6): 828-853, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28962014

RESUMO

In recent years, novel imaging approaches revolutionised our understanding of the cellular and molecular biology of microorganisms. These include advances in fluorescent probes, dynamic live cell imaging, superresolution light and electron microscopy. Currently, a major transition in the experimental approach shifts electron microscopy studies from a complementary technique to a method of choice for structural and functional analysis. Here we review functional insights into the molecular architecture of viruses, bacteria and parasites as well as interactions with their respective host cells gained from studies using cryogenic electron tomography and related methodologies.


Assuntos
Bactérias/ultraestrutura , Microscopia Eletrônica , Parasitos/ultraestrutura , Vírus/ultraestrutura , Animais
10.
Curr Pharm Des ; 23(23): 3342-3358, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28671059

RESUMO

In the absence of accessible, effective vaccines, the fight against parasitic disease relies mostly on chemotherapy. Nevertheless, the considerable side effects, high costs and growing number of refractory cases comprise substantial drawbacks. Thus, the search for new antiparasitic compounds remains a high priority. The polyamine biosynthesis, conversion and transport pathways offer different targets for selective chemotherapy. Polyamine analogues and other antagonists may provide tools in the search for new lead compounds. Light and electron microscopy techniques may encompass valuable approaches to elucidate the possible mechanisms of action of different antiparasitic compounds, allowing the identification of subcellular target compartments, presumably establishing the basis for a more rational drug design and/or planning of therapeutic strategies.


Assuntos
Antiparasitários/uso terapêutico , Parasitos/metabolismo , Parasitos/ultraestrutura , Poliaminas/metabolismo , Animais , Antineoplásicos/metabolismo , Antineoplásicos/uso terapêutico , Antiparasitários/metabolismo , Transporte Biológico/fisiologia , Humanos , Parasitos/efeitos dos fármacos , Doenças Parasitárias/tratamento farmacológico , Doenças Parasitárias/metabolismo
11.
Blood ; 130(8): 1031-1040, 2017 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-28634183

RESUMO

Band 3 (also known as the anion exchanger, SLCA1, AE1) constitutes the major attachment site of the spectrin-based cytoskeleton to the erythrocyte's lipid bilayer and thereby contributes critically to the stability of the red cell membrane. During the intraerythrocytic stage of Plasmodium falciparum's lifecycle, band 3 becomes tyrosine phosphorylated in response to oxidative stress, leading to a decrease in its affinity for the spectrin/actin cytoskeleton and causing global membrane destabilization. Because this membrane weakening is hypothesized to facilitate parasite egress and the consequent dissemination of released merozoites throughout the bloodstream, we decided to explore which tyrosine kinase inhibitors might block the kinase-induced membrane destabilization. We demonstrate here that multiple Syk kinase inhibitors both prevent parasite-induced band 3 tyrosine phosphorylation and inhibit parasite-promoted membrane destabilization. We also show that the same Syk kinase inhibitors suppress merozoite egress near the end of the parasite's intraerythrocytic lifecycle. Because the entrapped merozoites die when prevented from escaping their host erythrocytes and because some Syk inhibitors have displayed long-term safety in human clinical trials, we suggest Syk kinase inhibitors constitute a promising class of antimalarial drugs that can suppress parasitemia by inhibiting a host target that cannot be mutated by the parasite to evolve drug resistance.


Assuntos
Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/parasitologia , Parasitos/crescimento & desenvolvimento , Plasmodium falciparum/crescimento & desenvolvimento , Inibidores de Proteínas Quinases/farmacologia , Quinase Syk/antagonistas & inibidores , Adulto , Animais , Proteína 1 de Troca de Ânion do Eritrócito/metabolismo , Diferenciação Celular/efeitos dos fármacos , Membrana Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/ultraestrutura , Feminino , Humanos , Concentração Inibidora 50 , Malária Falciparum , Masculino , Parasitos/efeitos dos fármacos , Parasitos/ultraestrutura , Fosforilação/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/ultraestrutura , Quinase Syk/metabolismo
12.
J Exp Biol ; 219(Pt 24): 3866-3874, 2016 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-27974533

RESUMO

The highly specialized evolution of Strepsiptera has produced one of the most unusual eyes among mature insects, perhaps in line with their extremely complex and challenging life cycle. This relatively rare insect order is one of the few for which it has been unclear what spectral classes of photoreceptors any of its members may possess, an even more apt question given the nocturnal evolution of the group. To address this question, we performed electroretinograms on adult male Xenos peckii: we measured spectral responses to equi-quantal monochromatic light flashes of different wavelengths, and established VlogI relationships to calculate spectral sensitivities. Based on opsin template fits, we found maximal spectral sensitivity (λmax) in the green domain at 539 nm. Application of a green light to 'bleach' green receptors revealed that a UV peak was contributed to by an independent UV opsin with a λmax of 346 nm. Transcriptomics and a phylogenetic analysis including 50 other opsin sequences further confirmed the presence of these two opsin classes. While these findings do not necessarily indicate that these unorthodox insects have color vision, they raise the possibility that UV vision plays an important role in the ability of X. peckii males to find the very cryptic strepsipteran females that are situated within their wasp hosts.


Assuntos
Células Fotorreceptoras de Invertebrados/fisiologia , Raios Ultravioleta , Vespas/citologia , Vespas/fisiologia , Animais , Eletrorretinografia , Feminino , Masculino , Opsinas/genética , Opsinas/metabolismo , Parasitos/genética , Parasitos/ultraestrutura , Células Fotorreceptoras de Invertebrados/ultraestrutura , Filogenia , Análise Espectral , Transcriptoma/genética , Vespas/genética , Vespas/ultraestrutura
13.
Protist ; 167(6): 526-543, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27744090

RESUMO

Certain protist lineages bear cytoskeletal structures that are germane to them and define their individual group. Trichomonadida are excavate parasites united by a unique cytoskeletal framework, which includes tubulin-based structures such as the pelta and axostyle, but also other filaments such as the striated costa whose protein composition remains unknown. We determined the proteome of the detergent-resistant cytoskeleton of Tetratrichomonas gallinarum. 203 proteins with homology to Trichomonas vaginalis were identified, which contain significantly more long coiled-coil regions than control protein sets. Five candidates were shown to associate with previously described cytoskeletal structures including the costa and the expression of a single T. vaginalis protein in T. gallinarum induced the formation of accumulated, striated filaments. Our data suggests that filament-forming proteins of protists other than actin and tubulin share common structural properties with metazoan intermediate filament proteins, while not being homologous. These filament-forming proteins might have evolved many times independently in eukaryotes, or simultaneously in a common ancestor but with different evolutionary trajectories downstream in different phyla. The broad variety of filament-forming proteins uncovered, and with no homologs outside of the Trichomonadida, once more highlights the diverse nature of eukaryotic proteins with the ability to form unique cytoskeletal filaments.


Assuntos
Proteoma , Proteínas de Protozoários/metabolismo , Trichomonadida/ultraestrutura , Animais , Citoesqueleto/metabolismo , Citoesqueleto/ultraestrutura , Proteínas de Filamentos Intermediários/metabolismo , Microscopia Eletrônica de Transmissão , Parasitos/metabolismo , Parasitos/ultraestrutura , Trichomonadida/metabolismo
14.
J Cell Sci ; 129(17): 3320-31, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27457282

RESUMO

The apicomplexan protozoan Toxoplasma gondii, the causative agent of toxoplasmosis, harbors an apicoplast, a plastid-like organelle with essential metabolic functions. Although the FASII fatty acid biosynthesis pathway located in the apicoplast is essential for parasite survival, the cellular effects of FASII disruption in T. gondii had not been examined in detail. Here, we combined light and electron microscopy techniques - including focused ion beam scanning electron microscopy (FIB-SEM) - to characterize the effect of FASII disruption in T. gondii, by treatment with the FASII inhibitor triclosan or by inducible knockdown of the FASII component acyl carrier protein. Morphological analyses showed that FASII disruption prevented cytokinesis completion in T. gondii tachyzoites, leading to the formation of large masses of 'tethered' daughter cells. FIB-SEM showed that tethered daughters had a mature basal complex, but a defect in new membrane addition between daughters resulted in incomplete pellicle formation. Addition of exogenous fatty acids to medium suppressed the formation of tethered daughter cells and supports the notion that FASII is essential to generate lipid substrates required for the final step of parasite division.


Assuntos
Apicoplastos/metabolismo , Citocinese , Ácidos Graxos/biossíntese , Toxoplasma/citologia , Toxoplasma/metabolismo , Animais , Apicoplastos/ultraestrutura , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Ácido Graxo Sintases/metabolismo , Técnicas de Silenciamento de Genes , Estágios do Ciclo de Vida/efeitos dos fármacos , Macaca mulatta , Parasitos/citologia , Parasitos/efeitos dos fármacos , Parasitos/crescimento & desenvolvimento , Parasitos/ultraestrutura , Toxoplasma/crescimento & desenvolvimento , Toxoplasma/ultraestrutura , Triclosan/farmacologia
15.
Cell Mol Life Sci ; 73(21): 4141-58, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27193441

RESUMO

Antibodies to blood-stage antigens of Plasmodium falciparum play a pivotal role in human immunity to malaria. During parasite development, multiple proteins are trafficked from the intracellular parasite to the surface of P. falciparum-infected erythrocytes (IEs). However, the relative importance of different proteins as targets of acquired antibodies, and key pathways involved in trafficking major antigens remain to be clearly defined. We quantified antibodies to surface antigens among children, adults, and pregnant women from different malaria-exposed regions. We quantified the importance of antigens as antibody targets using genetically engineered P. falciparum with modified surface antigen expression. Genetic deletion of the trafficking protein skeleton-binding protein-1 (SBP1), which is involved in trafficking the surface antigen PfEMP1, led to a dramatic reduction in antibody recognition of IEs and the ability of human antibodies to promote opsonic phagocytosis of IEs, a key mechanism of parasite clearance. The great majority of antibody epitopes on the IE surface were SBP1-dependent. This was demonstrated using parasite isolates with different genetic or phenotypic backgrounds, and among antibodies from children, adults, and pregnant women in different populations. Comparisons of antibody reactivity to parasite isolates with SBP1 deletion or inhibited PfEMP1 expression suggest that PfEMP1 is the dominant target of acquired human antibodies, and that other P. falciparum IE surface proteins are minor targets. These results establish SBP1 as part of a critical pathway for the trafficking of major surface antigens targeted by human immunity, and have key implications for vaccine development, and quantifying immunity in populations.


Assuntos
Anticorpos/imunologia , Antígenos de Protozoários/metabolismo , Eritrócitos/parasitologia , Malária Falciparum/imunologia , Malária Falciparum/parasitologia , Plasmodium falciparum/imunologia , Animais , Proteínas de Transporte/metabolismo , Eritrócitos/ultraestrutura , Técnicas de Inativação de Genes , Humanos , Proteínas de Membrana/metabolismo , Parasitos/imunologia , Parasitos/ultraestrutura , Fenótipo , Plasmodium falciparum/ultraestrutura , Transporte Proteico , Proteínas de Protozoários/metabolismo
16.
Microsc Res Tech ; 78(9): 771-6, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26178782

RESUMO

An easy and low-cost method to elaborate a container to dehydrate nematodes and other meiofauna in order to process them for scanning electron microscopy (SEM) is presented. Illustrations of its elaboration, step by step, are included. In addition, a brief methodology to process meiofauna, especially nematodes and kinorhynchs, and illustrations are provided. With this methodology it is possible to easily introduce the specimens, to lock them in a closed chamber allowing the infiltration of fluids and gases (ethanol, acetone, carbon dioxide) but avoiding losing the specimens. After using this meiofauna basket for SEM the results are efficient. Examples of nematode and kinorhynch SEM pictures obtained using this methodology are also included.


Assuntos
Invertebrados/ultraestrutura , Microscopia Eletrônica de Varredura , Parasitos/isolamento & purificação , Parasitos/ultraestrutura , Parasitologia/métodos , Água/parasitologia , Animais , Parasitologia/economia
17.
Autophagy ; 11(9): 1561-79, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26208778

RESUMO

Plasmodium parasites are transmitted by Anopheles mosquitoes to the mammalian host and actively infect hepatocytes after passive transport in the bloodstream to the liver. In their target host hepatocyte, parasites reside within a parasitophorous vacuole (PV). In the present study it was shown that the parasitophorous vacuole membrane (PVM) can be targeted by autophagy marker proteins LC3, ubiquitin, and SQSTM1/p62 as well as by lysosomes in a process resembling selective autophagy. The dynamics of autophagy marker proteins in individual Plasmodium berghei-infected hepatocytes were followed by live imaging throughout the entire development of the parasite in the liver. Although the host cell very efficiently recognized the invading parasite in its vacuole, the majority of parasites survived this initial attack. Successful parasite development correlated with the gradual loss of all analyzed autophagy marker proteins and associated lysosomes from the PVM. However, other autophagic events like nonselective canonical autophagy in the host cell continued. This was indicated as LC3, although not labeling the PVM anymore, still localized to autophagosomes in the infected host cell. It appears that growing parasites even benefit from this form of nonselective host cell autophagy as an additional source of nutrients, as in host cells deficient for autophagy, parasite growth was retarded and could partly be rescued by the supply of additional amino acid in the medium. Importantly, mouse infections with P. berghei sporozoites confirmed LC3 dynamics, the positive effect of autophagy activation on parasite growth, and negative effects upon autophagy inhibition.


Assuntos
Citosol/imunologia , Hepatócitos/imunologia , Imageamento Tridimensional , Evasão da Resposta Imune , Imunidade , Malária/imunologia , Parasitos/imunologia , Plasmodium berghei/patogenicidade , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Autofagia , Biomarcadores/metabolismo , Galectinas/metabolismo , Proteínas de Choque Térmico/metabolismo , Células Hep G2 , Hepatócitos/parasitologia , Hepatócitos/ultraestrutura , Humanos , Membranas Intracelulares/metabolismo , Membranas Intracelulares/ultraestrutura , Estágios do Ciclo de Vida , Fígado/parasitologia , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Malária/parasitologia , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Parasitos/crescimento & desenvolvimento , Parasitos/patogenicidade , Parasitos/ultraestrutura , Plasmodium berghei/crescimento & desenvolvimento , Plasmodium berghei/ultraestrutura , Proteína Sequestossoma-1 , Esporozoítos/fisiologia , Esporozoítos/ultraestrutura , Análise de Sobrevida , Fatores de Tempo , Ubiquitina/metabolismo , Ubiquitinação , Vacúolos/metabolismo , Vacúolos/ultraestrutura , Virulência
18.
Tissue Cell ; 47(3): 235-41, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25796547

RESUMO

The ultrastructural organization of the spermatozoon of the digenean Tergestia acanthocephala (Gymnophalloidea: Fellodistomidae) is described. Live digeneans were collected from Belone belone gracilis (Teleostei: Belonidae), caught off the Gulf of Gabès in Chebba (Tunisia). The mature spermatozoon of T. acanthocephala exhibits the general pattern described in numerous digeneans, characterized by the presence of two axonemes of the different length of the 9+'1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies and granules of glycogen. Moreover, the morphology of the posterior spermatozoon extremity in T. acanthocephala corresponds to the fasciolidean type of Quilichini et al. (2010a).


Assuntos
Peixes/parasitologia , Microscopia Eletrônica de Transmissão , Parasitos/patogenicidade , Espermatozoides/ultraestrutura , Acantocéfalos/ultraestrutura , Animais , Basidiomycota/patogenicidade , Basidiomycota/ultraestrutura , Membrana Celular/ultraestrutura , Núcleo Celular/ultraestrutura , Masculino , Microtúbulos/ultraestrutura , Mitocôndrias/ultraestrutura , Parasitos/ultraestrutura
19.
Proc Natl Acad Sci U S A ; 111(43): 15480-5, 2014 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-25313038

RESUMO

Intracellular parasitism results in extreme adaptations, whose evolutionary history is difficult to understand, because the parasites and their known free-living relatives are so divergent from one another. Microsporidia are intracellular parasites of humans and other animals, which evolved highly specialized morphological structures, but also extreme physiologic and genomic simplification. They are suggested to be an early-diverging branch on the fungal tree, but comparisons to other species are difficult because their rates of molecular evolution are exceptionally high. Mitochondria in microsporidia have degenerated into organelles called mitosomes, which have lost a genome and the ability to produce ATP. Here we describe a gut parasite of the crustacean Daphnia that despite having remarkable morphological similarity to the microsporidia, has retained genomic features of its fungal ancestors. This parasite, which we name Mitosporidium daphniae gen. et sp. nov., possesses a mitochondrial genome including genes for oxidative phosphorylation, yet a spore stage with a highly specialized infection apparatus--the polar tube--uniquely known only from microsporidia. Phylogenomics places M. daphniae at the root of the microsporidia. A comparative genomic analysis suggests that the reduction in energy metabolism, a prominent feature of microsporidian evolution, was preceded by a reduction in the machinery controlling cell cycle, DNA recombination, repair, and gene expression. These data show that the morphological features unique to M. daphniae and other microsporidia were already present before the lineage evolved the extreme host metabolic dependence and loss of mitochondrial respiration for which microsporidia are well known.


Assuntos
Evolução Molecular , Genoma Fúngico/genética , Microsporídios/genética , Parasitos/anatomia & histologia , Parasitos/genética , Filogenia , Animais , Genômica , Microsporídios/ultraestrutura , Anotação de Sequência Molecular , Dados de Sequência Molecular , Parasitos/ultraestrutura , Análise de Sequência de DNA , Especificidade da Espécie
20.
Curr Biol ; 24(7): R262-3, 2014 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-24698369
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