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1.
Parasitol Res ; 119(7): 2237-2244, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32451718

RESUMO

Ecological data on marine mammal parasites represent an excellent opportunity to expand our understanding of host-parasite systems. In this study, we used a dataset of intestinal helminth parasites on 167 long-finned pilot whales Globicephala melas (Traill, 1809) from seven localities in the Faroe Islands to evaluate the extent to which the host's age and sex influence the occurrence, richness, and nested pattern of helminth parasites and the importance of individual hosts to the helminth community. We found positive effects of age on both the occurrence and richness of helminths. Older host individuals showed an ordered accumulation of parasites, as evidenced by the nested pattern in their composition. Males had a higher occurrence of parasites than females, but the richness of helminths did not differ between sexes. Our findings suggest that differences in host-parasite interactions in long-finned pilot whales result mainly from age-structured variations in biological and behavioral characteristics.


Assuntos
Helmintíase/epidemiologia , Helmintos/isolamento & purificação , Interações Hospedeiro-Parasita/fisiologia , Baleias Piloto/parasitologia , Distribuição por Idade , Fatores Etários , Animais , Dinamarca/epidemiologia , Feminino , Humanos , Intestinos/parasitologia , Masculino , Fatores Sexuais
2.
Parasitol Res ; 119(7): 2039-2045, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32377908

RESUMO

Ticks are ectoparasites that feed on blood of a broad taxonomic range of terrestrial and flying vertebrates and are distributed across a wide range of environmental conditions. Here, we explore the biotic and abiotic factors on infestation probability of ticks of the genus Amblyomma and assess the degree of host specificity based on analysis of 1028 birds surveyed across Brazil. We show that tick infestation rates exhibited considerable variation across the 235 avian species analyzed and that the probability of an individual bird being parasitized by immature ticks (larvae and nymphs) increased with annual precipitation. Host phylogeny and two host ecological traits known to promote tick exposure (body mass and foraging behavior) did not predict infestation probability. Moreover, immature ticks displayed a low degree of host specificity at the family level. Lastly, tick occurrence in birds carrying infection with avian malaria and related parasites did not differ from those free of these haemosporidian parasites, indicating a lack of parasite avoidance by immature ticks. Our findings demonstrate that tick occurrence in birds across Brazilian biomes responds to environmental factors rather than ecological and evolutionary host attributes.


Assuntos
Aves/parasitologia , Meio Ambiente , Especificidade de Hospedeiro/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Ixodidae/fisiologia , Infestações por Carrapato/veterinária , Animais , Doenças das Aves/epidemiologia , Doenças das Aves/parasitologia , Brasil/epidemiologia , Larva , Malária Aviária/epidemiologia , Ninfa , Filogenia
3.
Parasitol Res ; 119(7): 2005-2023, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32394001

RESUMO

The focus of this review is a group of structures/organelles collectively known as extracellular vesicles (EVs) that are secreted by most, if not all, cells, varying from mammalian cells to protozoa and even bacteria. They vary in size: some are small (100-200 nm) and others are larger (> 200 nm). In protozoa, however, most of them are small or medium in size (200-400 nm). These include vesicles from different origins. We briefly review the biogenesis of this distinct group that includes (a) exosome, which originates from the multivesicular bodies, an important component of the endocytic pathway; (b) ectosome, formed from a budding process that takes place in the plasma membrane of the cells; (c) vesicles released from the cell surface following a process of patching and capping of ligand/receptor complexes; (d) other processes where tubules secreted by the parasite subsequently originate exosome-like structures. Here, special emphasis is given to EVs secreted by parasitic protozoa such as Leishmania, Trypanosoma, Plasmodium, Toxoplasma, Cryptosporidium, Trichomonas, and Giardia. Most of them have been characterized as exosomes that were isolated using several approaches and characterized by electron microscopy, proteomic analysis, and RNA sequencing. The results obtained show clearly that they present several proteins and different types of RNAs. From the functional point of view, it is now clear that the secreted exosomes can be incorporated by the parasite itself as well as by mammalian cells with which they interact. As a consequence, there is interference both with the parasite (induction of differentiation, changes in infectivity, etc.) and with the host cell. Therefore, the EVs constitute a new system of transference of signals among cells. On the other hand, there are suggestions that exosomes may constitute potential biotechnology tools and are important players of what has been designated as nanobiotechnology. They may constitute an important delivery system for gene therapy and molecular-displaying cell regulation capabilities when incorporated into other cells and even by interfering with the exosomal membrane during its biogenesis, targeting the vesicles via specific ligands to different cell types. These vesicles may reach the bloodstream, overflow through intercellular junctions, and even pass through the central nervous system blood barrier. There is evidence that it is possible to interfere with the composition of the exosomes by interfering with multivesicular body biogenesis.


Assuntos
Membrana Celular/metabolismo , Eucariotos/metabolismo , Vesículas Extracelulares/metabolismo , Interações Hospedeiro-Parasita/fisiologia , Proteínas de Protozoários/metabolismo , Animais , Transporte Biológico , Exossomos/metabolismo , Vesículas Extracelulares/fisiologia , Humanos , Microscopia Eletrônica , Proteômica
4.
Parasitol Res ; 119(7): 2093-2104, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32462294

RESUMO

We studied patterns of ectoparasite species turnover and pairwise ectoparasite-host interactions across space and time in fleas and mites harboured by small mammals using a novel metric, zeta diversity (similarity between multiple communities). We asked whether the zeta diversity of parasites and their interactions with hosts follow a similar spatial or temporal trend. We found substantial differences in some (zeta decline and retention rate) but not in other (zeta decay) spatial patterns of zeta diversity between species and interactions, whereas the differences between the patterns of the temporal species versus interaction zeta diversity occurred to a much lesser extent. In particular, the parametric form of zeta decline suggested that the distribution of ectoparasite species across localities is driven mainly by niche-based processes, whereas the spatial distribution of flea-host and mite-host interactions is predominantly stochastic. We also found much stronger variation in the number of shared species and interactions over space than over time. Parasite community composition, in terms of species, appeared to be much more temporally stable than that in terms of parasite-host interactions. The parametric form of temporal zeta decline indicated that both parasite communities and parasite-host networks are assembled over time via niche-based processes.


Assuntos
Infestações por Pulgas/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Mamíferos/parasitologia , Infestações por Ácaros/parasitologia , Distribuição Animal , Animais , Infestações por Pulgas/epidemiologia , Especificidade de Hospedeiro , Infestações por Ácaros/epidemiologia , Ácaros , Sifonápteros , Fatores de Tempo
5.
Science ; 368(6492): 746-753, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32409471

RESUMO

Malarial rhythmic fevers are the consequence of the synchronous bursting of red blood cells (RBCs) on completion of the malaria parasite asexual cell cycle. Here, we hypothesized that an intrinsic clock in the parasite Plasmodium chabaudi underlies the 24-hour-based rhythms of RBC bursting in mice. We show that parasite rhythms are flexible and lengthen to match the rhythms of hosts with long circadian periods. We also show that malaria rhythms persist even when host food intake is evenly spread across 24 hours, suggesting that host feeding cues are not required for synchrony. Moreover, we find that the parasite population remains synchronous and rhythmic even in an arrhythmic clock mutant host. Thus, we propose that parasite rhythms are generated by the parasite, possibly to anticipate its circadian environment.


Assuntos
Ritmo Circadiano/fisiologia , Febre/fisiopatologia , Febre/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Malária/fisiopatologia , Malária/parasitologia , Plasmodium chabaudi/fisiologia , Animais , Proteínas CLOCK/genética , Ritmo Circadiano/genética , Sinais (Psicologia) , Escuridão , Ingestão de Alimentos , Eritrócitos/parasitologia , Comportamento Alimentar , Regulação da Expressão Gênica , Interações Hospedeiro-Parasita/genética , Camundongos , Camundongos Mutantes , Plasmodium chabaudi/genética , Transcrição Genética
6.
PLoS Pathog ; 16(5): e1008539, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32459815

RESUMO

NAD, a key co-enzyme required for cell metabolism, is synthesized via two pathways in most organisms. Since schistosomes apparently lack enzymes required for de novo NAD biosynthesis, we evaluated whether these parasites, which infect >200 million people worldwide, maintain NAD homeostasis via the NAD salvage biosynthetic pathway. We found that intracellular NAD levels decline in schistosomes treated with drugs that block production of nicotinamide or nicotinamide mononucleotide-known NAD precursors in the non-deamidating salvage pathway. Moreover, in vitro inhibition of the NAD salvage pathway in schistosomes impaired egg production, disrupted the outer membranes of both immature and mature parasites and caused loss of mobility and death. Inhibiting the NAD salvage pathway in schistosome-infected mice significantly decreased NAD levels in adult parasites, which correlated with reduced egg production, fewer liver granulomas and parasite death. Thus, schistosomes, unlike their mammalian hosts, appear limited to one metabolic pathway to maintain NAD-dependent metabolic processes.


Assuntos
Interações Hospedeiro-Parasita/fisiologia , NAD/metabolismo , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/metabolismo , Animais , Feminino , Camundongos , Reprodução/fisiologia , Esquistossomose mansoni/patologia
7.
Science ; 368(6492): 754-759, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32409472

RESUMO

The blood stage of the infection of the malaria parasite Plasmodium falciparum exhibits a 48-hour developmental cycle that culminates in the synchronous release of parasites from red blood cells, which triggers 48-hour fever cycles in the host. This cycle could be driven extrinsically by host circadian processes or by a parasite-intrinsic oscillator. To distinguish between these hypotheses, we examine the P. falciparum cycle in an in vitro culture system and show that the parasite has molecular signatures associated with circadian and cell cycle oscillators. Each of the four strains examined has a different period, which indicates strain-intrinsic period control. Finally, we demonstrate that parasites have low cell-to-cell variance in cycle period, on par with a circadian oscillator. We conclude that an intrinsic oscillator maintains Plasmodium's rhythmic life cycle.


Assuntos
Relógios Circadianos/fisiologia , Eritrócitos/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Estágios do Ciclo de Vida , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Animais , Relógios Circadianos/genética , Expressão Gênica , Genes de Protozoários/fisiologia , Interações Hospedeiro-Parasita/genética , Camundongos , Plasmodium falciparum/genética , Transcriptoma
8.
Adv Parasitol ; 108: 175-229, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32291085

RESUMO

In the past two decades, significant progress has been made in the sequencing, assembly, annotation and analyses of genomes and transcriptomes of parasitic worms of socioeconomic importance. This progress has somewhat improved our knowledge and understanding of these pathogens at the molecular level. However, compared with the free-living nematode Caenorhabditis elegans, the areas of functional genomics, transcriptomics, proteomics and metabolomics of parasitic nematodes are still in their infancy, and there are major gaps in our knowledge and understanding of the molecular biology of parasitic nematodes. The information on signalling molecules, molecular pathways and microRNAs (miRNAs) that are known to be involved in developmental processes in C. elegans and the availability of some molecular resources (draft genomes, transcriptomes and some proteomes) for selected parasitic nematodes provide a basis to start exploring the developmental biology of parasitic nematodes. Indeed, some studies have identified molecules and pathways that might associate with developmental processes in related, parasitic nematodes, such as Haemonchus contortus (barber's pole worm). However, detailed information is often scant and 'omics resources are limited, preventing a proper integration of 'omic data sets and comprehensive analyses. Moreover, little is known about the functional roles of pheromones, hormones, signalling pathways and post-transcriptional/post-translational regulations in the development of key parasitic nematodes throughout their entire life cycles. Although C. elegans is an excellent model to assist molecular studies of parasitic nematodes, its use is limited when it comes to explorations of processes that are specific to parasitism within host animals. A deep understanding of parasitic nematodes, such as H. contortus, requires substantially enhanced resources and the use of integrative 'omics approaches for analyses. The improved genome and well-established in vitro larval culture system for H. contortus provide unprecedented opportunities for comprehensive studies of the transcriptomes (mRNA and miRNA), proteomes (somatic, excretory/secretory and phosphorylated proteins) and lipidomes (e.g., polar and neutral lipids) of this nematode. Such resources should enable in-depth explorations of its developmental biology at a level, not previously possible. The main aims of this review are (i) to provide a background on the development of nematodes, with a particular emphasis on the molecular aspects involved in the dauer formation and exit in C. elegans; (ii) to critically appraise the current state of knowledge of the developmental biology of parasitic nematodes and identify key knowledge gaps; (iii) to cover salient aspects of H. contortus, with a focus on the recent advances in genomics, transcriptomics, proteomics and lipidomics as well as in vitro culturing systems; (iv) to review recent advances in our knowledge and understanding of the molecular and developmental biology of H. contortus using an integrative multiomics approach, and discuss the implications of this approach for detailed explorations of signalling molecules, molecular processes and pathways likely associated with nematode development, adaptation and parasitism, and for the identification of novel intervention targets against these pathogens. Clearly, the multiomics approach established recently is readily applicable to exploring a wide range of interesting and socioeconomically significant parasitic worms (including also trematodes and cestodes) at the molecular level, and to elucidate host-parasite interactions and disease processes.


Assuntos
Biologia Computacional , Nematoides/crescimento & desenvolvimento , Nematoides/genética , Infecções por Nematoides/parasitologia , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Interações Hospedeiro-Parasita/fisiologia , Humanos , Parasitos/genética , Parasitos/crescimento & desenvolvimento
9.
BMC Evol Biol ; 20(1): 37, 2020 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-32171235

RESUMO

BACKGROUND: Various ecological groups of earthworms very likely constitute sharply isolated niches that might permit speciation of their symbiotic ciliates, even though no distinct morphological features appear to be recognizable among ciliates originating from different host groups. The nuclear highly variable ITS1-5.8S-ITS2 region and the hypervariable D1/D2 region of the 28S rRNA gene have proven to be useful tools for the delimitation of species boundaries in closely related free-living ciliate taxa. In the present study, the power of these molecular markers as well as of the secondary structure of the ITS2 molecule were tested for the first time in order to discriminate the species of endosymbiotic ciliates that were isolated from the gastrointestinal tract of three ecologically different groups of lumbricid earthworms. RESULTS: Nineteen new ITS1-5.8S-ITS2 region and D1/D2-28S rRNA gene sequences were obtained from five astome species (Anoplophrya lumbrici, A. vulgaris, Metaradiophrya lumbrici, M. varians, and Subanoplophrya nodulata comb. n.), which were living in the digestive tube of three ecological groups of earthworms. Phylogenetic analyses of the rRNA locus and secondary structure analyses of the ITS2 molecule robustly resolved their phylogenetic relationships and supported the distinctness of all five species, although previous multivariate morphometric analyses were not able to separate congeners in the genera Anoplophrya and Metaradiophrya. The occurrence of all five taxa, as delimited by molecular analyses, was perfectly correlated with the ecological groups of their host earthworms. CONCLUSIONS: The present study indicates that morphology-based taxonomy of astome ciliates needs to be tested in the light of molecular and ecological data as well. The use of morphological identification alone is likely to miss species that are well delimited based on molecular markers and ecological traits and can lead to the underestimation of diversity and overestimation of host range. An integrative approach along with distinctly increased taxon sampling would be helpful to assess the consistency of the eco-evolutionary trend in astome ciliates.


Assuntos
Cilióforos/classificação , Cilióforos/isolamento & purificação , DNA Espaçador Ribossômico/genética , Trato Gastrointestinal/parasitologia , Oligoquetos/parasitologia , RNA Ribossômico 28S/genética , Animais , Cilióforos/genética , DNA Espaçador Ribossômico/análise , Ecologia , Genes de RNAr/genética , Interações Hospedeiro-Parasita/fisiologia , Oligoquetos/classificação , Oligoquetos/genética , Filogenia , RNA Ribossômico , RNA Ribossômico 28S/análise , Análise de Sequência de DNA
10.
Proc Natl Acad Sci U S A ; 117(11): 5970-5976, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32123093

RESUMO

Host manipulation by parasites is a fascinating evolutionary outcome, but adaptive scenarios that often accompany even iconic examples in this popular field of study are speculative. Kin selection has been invoked as a means of explaining the evolution of an altruistic-based, host-manipulating behavior caused by larvae of the lancet fluke Dicrocoelium dendriticum in ants. Specifically, cotransmission of larval clonemates from a snail first host to an ant second host is presumed to lead to a puppeteer parasite in the ant's brain that has clonemates in the ant abdomen. Clonal relatedness between the actor (brain fluke) and recipients (abdomen flukes) enables kin selection of the parasite's host-manipulating trait, which facilitates transmission of the recipients to the final host. However, the hypothesis that asexual reproduction in the snail leads to a high abundance of clonemates in the same ant is untested. Clonal relationships between the manipulator in the brain and the nonmanipulators in the abdomen are also untested. We provide empirical data on the lancet fluke's clonal diversity within its ant host. In stark contrast to other trematodes, which do not exhibit the same host-manipulating behavioral trait, the lancet fluke has a high abundance of clonemates. Moreover, our data support existing theory that indicates that the altruistic behavior can evolve even in the presence of multiple clones within the same ant host. Importantly, our analyses conclusively show clonemate cotransmission into ants, and, as such, we find support for kin selection to drive the evolution and maintenance of this iconic host manipulation.


Assuntos
Evolução Biológica , Interações Hospedeiro-Parasita/fisiologia , Parasitos/fisiologia , Animais , Formigas/parasitologia , Formigas/fisiologia , Comportamento Animal , Dicrocoelium/parasitologia , Interações Hospedeiro-Parasita/genética , Larva , Linhagem , Caramujos/parasitologia , Trematódeos/genética , Trematódeos/fisiologia
11.
BMC Infect Dis ; 20(1): 188, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32122317

RESUMO

BACKGROUND: In recent times, Plasmodium vivax (P. vivax) has become a serious threat to public health due to its ability to cause severe infection with fatal outcomes. Its unique biology makes it resilient to control measures that are otherwise effective against P. falciparum. A deeper understanding of P. vivax biology and pathogenesis is, therefore, essential for developing the right control strategies. Proteomics of P. falciparum has been helpful in studying disease biology and elucidating molecular mechanisms involved in the development of disease. However, unlike P. falciparum, proteomics data for P. vivax infection is minimal due to the absence of a continuous culture system. The dependence on clinical samples and animal models has drastically limited P. vivax research, creating critical knowledge gaps in our understanding of the disease. This study describes an in-depth proteomics analysis of P. vivax-infected human plasma and parasite isolates, to understand parasite biology, pathogenesis, and to identify new diagnostic targets for P. vivax malaria. METHODS: A mass-spectrometry- (MS) based proteomics approach (Q Exactive) was applied to analyze human plasma and parasite isolates from vivax malaria patients visiting a primary health centre in India. Additionally, a targeted proteomics assay was standardized for validating unique peptides of most recurring parasite proteins. RESULTS: Thirty-eight P. vivax proteins were detected in human plasma with high confidence. Several glycolytic enzymes were found along with hypothetical, cytoskeletal, ribosomal, and nuclear proteins. Additionally, 103 highly abundant P. vivax proteins were detected in parasite isolates. This represents the highest number of parasite proteins to be reported from clinical samples so far. Interestingly, five of these; three Plasmodium exported proteins (PVX_003545, PVX_003555 and PVX_121935), a hypothetical protein (PVX_083555) and Pvstp1 (subtelomeric transmembrane protein 1, PVX_094303) were found in both plasma and parasite isolates. CONCLUSIONS: A parasite proteomics investigation is essential to understand disease pathobiology and design novel interventions. Control strategies against P. vivax also depend on early diagnosis. This work provides deeper insights into the biology of P. vivax by identifying proteins expressed by the parasite during its complex life-cycle within the human host. The study also reports antigens that may be explored as diagnostic candidates.


Assuntos
Malária Vivax/sangue , Plasmodium vivax/isolamento & purificação , Proteínas de Protozoários/sangue , Ontologia Genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Índia , Estágios do Ciclo de Vida , Malária Vivax/parasitologia , Plasmodium vivax/fisiologia , Proteômica/métodos , Proteínas de Protozoários/análise , Proteínas de Protozoários/genética , Espectrometria de Massas em Tandem
12.
Protist ; 171(1): 125709, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32004979

RESUMO

This study investigated protist community composition and biotic interactions focusing on microplankton at four distinct sites around the Kerguelen Islands (Southern Ocean) after the summer phytoplankton bloom. Protist diversity in different size fractions, sampled with Niskin bottles and plankton nets, was assessed by sequencing of the V4 18S rDNA region. Combining different approaches, i.e. sequencing of different plankton size fractions, and isolation and sequencing of single cells, provided new insights into microbial interactions in protist communities. The communities displayed high variability, including short-term fluctuations in relative abundance of large protists (>35µm) highlighted by the plankton net samples. Size fractionation of protist communities showed high concentrations of free Syndiniales spores but relatively few Syndiniales associated with microplankton, suggesting low parasitic infection in early autumn. Co-variance network analyses and sequencing of individually isolated single cells highlighted the important role of Rhizaria as consumers of a wide range of different diatom taxa. The data also raised the hypothesis that different Syndiniales clades might be directly or indirectly associated with some diatom genera, thus suggesting a potentially wider host range of these parasites than has been previously reported. These associations and the potential impact on carbon fluxes are discussed.


Assuntos
Biodiversidade , Interações Hospedeiro-Parasita/fisiologia , Plâncton/classificação , Estações do Ano , Água do Mar/parasitologia , Eucariotos/fisiologia , Oceanos e Mares , Plâncton/genética , Plâncton/microbiologia , RNA Ribossômico 18S/genética , Água do Mar/microbiologia
13.
PLoS One ; 15(2): e0228880, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32040535

RESUMO

Despite its high ecological importance, the commensal interactions at community level are poorly studied. In tropical dry forests (TDF) there is a great diversity of species adapted to the high seasonality that characterizes them; however, little is known regarding how the spatial and temporal availability of resources generates changes in the pattern of commensal interactions. We experimentally studied changes in the diversity, composition, and pattern of interactions in spatio-temporal associations between the saproxylophagous beetles and their host trees in a TDF in Morelos, Mexico. A total of 65 host tree species were selected, from which 16 wood sections were obtained per species. These sections were exposed in the field to allow oviposition by the cerambycids under four different (spatio-temporal) treatments. We analyzed the network structure and generated indices at species level (i.e., specialization, species strength, and effective partners) and those related to physical characteristics of the wood (hardness and degradation rate) and the cerambycids (body size). In total, 1,323 individuals of 57 species of cerambycids emerged. Our results showed that, independently of the space and time, the network presented a nested and modular structure, with a high specialization degree and a high turnover of cerambycid species and their interactions. In general, we found that the cerambycids are mostly associated with softwood species with a lower decomposition rate of wood, as well as with the most abundant host species. The commensalistic interactions between the cerambycids and their host trees are highly specialized but are not spatio-temporally static. The high turnover in the interactions is caused by the emergence patterns of cerambycids, which seem to restrict their use to certain species. The knowledge of the spatio-temporal variation in Cerambycidae-host tree interactions allows us to predict how environmental and structural changes in the habitat can modify the species ensemble, and therefore its interactions.


Assuntos
Besouros/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Árvores/parasitologia , Animais , Biodiversidade , Besouros/patogenicidade , Ecossistema , Feminino , Florestas , Especificidade de Hospedeiro , México , Oviposição , Análise Espaço-Temporal , Simbiose/fisiologia , Clima Tropical , Madeira
14.
PLoS One ; 15(1): e0227832, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31945116

RESUMO

Here we characterized the development of the trypanosomatid Blastocrithidia raabei in the dock bug Coreus marginatus using light and electron microscopy. This parasite has been previously reported to occur in the host hemolymph, which is rather typical for dixenous trypanosomatids transmitted to a plant or vertebrate with insect's saliva. In addition, C. marginatus has an unusual organization of the intestine, which makes it refractory to microbial infections: two impassable segments isolate the anterior midgut portion responsible for digestion and absorption from the posterior one containing symbiotic bacteria. Our results refuted the possibility of hemolymph infection, but revealed that the refractory nature of the host provokes very aggressive behavior of the parasite and makes its life cycle more complex, reminiscent of that in some dixenous trypanosomatids. In the pre-barrier midgut portion, the epimastigotes of B. raabei attach to the epithelium and multiply similarly to regular insect trypanosomatids. However, when facing the impassable constricted region, the parasites rampage and either fiercely break through the isolating segments or attack the intestinal epithelium in front of the barrier. The cells of the latter group pass to the basal lamina and accumulate there, causing degradation of the epitheliocytes and thus helping the epimastigotes of the former group to advance posteriorly. In the symbiont-containing post-barrier midgut segment, the parasites either attach to bacterial cells and produce cyst-like amastigotes (CLAs) or infect enterocytes. In the rectum, all epimastigotes attach either to the cuticular lining or to each other and form CLAs. We argue that in addition to the specialized life cycle B. raabei possesses functional cell enhancements important either for the successful passage through the intestinal barriers (enlarged rostrum and well-developed Golgi complex) or as food reserves (vacuoles in the posterior end).


Assuntos
Infecções por Euglenozoa/veterinária , Heterópteros/imunologia , Interações Hospedeiro-Parasita/fisiologia , Estágios do Ciclo de Vida/fisiologia , Trypanosomatina/crescimento & desenvolvimento , Animais , Resistência à Doença , Infecções por Euglenozoa/imunologia , Infecções por Euglenozoa/parasitologia , Hemolinfa/parasitologia , Heterópteros/parasitologia , Mucosa Intestinal/diagnóstico por imagem , Mucosa Intestinal/parasitologia , Mucosa Intestinal/ultraestrutura , Microscopia Eletrônica , Trypanosomatina/patogenicidade , Trypanosomatina/ultraestrutura
15.
Nat Commun ; 11(1): 208, 2020 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924834

RESUMO

Microorganisms and nematodes in the rhizosphere profoundly impact plant health, and small-molecule signaling is presumed to play a central role in plant rhizosphere interactions. However, the nature of the signals and underlying mechanisms are poorly understood. Here we show that the ascaroside ascr#18, a pheromone secreted by plant-parasitic nematodes, is metabolized by plants to generate chemical signals that repel nematodes and reduce infection. Comparative metabolomics of plant tissues and excretions revealed that ascr#18 is converted into shorter side-chained ascarosides that confer repellency. An Arabidopsis mutant defective in two peroxisomal acyl-CoA oxidases does not metabolize ascr#18 and does not repel nematodes, indicating that plants, like nematodes, employ conserved peroxisomal ß-oxidation to edit ascarosides and change their message. Our results suggest that plant-editing of nematode pheromones serves as a defense mechanism that acts in parallel to conventional pattern-triggered immunity, demonstrating that plants may actively manipulate chemical signaling of soil organisms.


Assuntos
Arabidopsis/metabolismo , Arabidopsis/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Nematoides/metabolismo , Feromônios/metabolismo , Acil-CoA Oxidase , Animais , Arabidopsis/imunologia , Lycopersicon esculentum , Metabolômica , Oxirredução , Doenças das Plantas/imunologia , Doenças das Plantas/parasitologia , Imunidade Vegetal , Raízes de Plantas/metabolismo , Transdução de Sinais , Triticum
16.
Parasitol Res ; 119(2): 423-430, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31912275

RESUMO

A prerequisite for a parasitic manipulation to be considered adaptive is that it confers a fitness benefit to the parasite, such as increased transmission to another host. These manipulations can involve alterations to a wide range of host phenotypic traits, including microhabitat choice. Eye flukes of the trematode family Diplostomidae use fish as intermediate hosts and must be transmitted by predation to a piscivorous bird. In New Zealand, the diplostomid Tylodelphys darbyi infects the eyes of a widespread endemic freshwater fish, the common bully Gobiomorphus cotidianus. Within the eye, T. darbyi metacercariae achieve large sizes and move freely about the aqueous and vitreous humors of the eye. We hypothesized that higher intensities of T. darbyi would (i) cause bullies to show increased activity and spend more time moving about in open space (i.e., more conspicuous, risky microhabitat) and (ii) reduce their ability to compete for shelter with fish harboring lower infection levels. Our experiments showed that heavily infected fish were more active and spent more time in the open, although the effect was age-dependent, with immature fish displaying decreases in activity and time spent in the open with increasing intensities of infection. We also demonstrated that heavily infected female bullies have a lower probability of using shelter, but males show the opposite pattern. It is possible that using more risky microhabitats increases the likelihood of the fish being eaten by the parasite's predatory avian definitive hosts. However, our findings indicate that age- and sex-dependent effects call for a more nuanced interpretation.


Assuntos
Oftalmopatias/parasitologia , Olho/patologia , Perciformes/parasitologia , Trematódeos/patogenicidade , Infecções por Trematódeos/veterinária , Transtornos da Visão/parasitologia , Animais , Olho/parasitologia , Feminino , Doenças dos Peixes/parasitologia , Peixes/parasitologia , Água Doce , Interações Hospedeiro-Parasita/fisiologia , Masculino , Metacercárias , Nova Zelândia , Comportamento Predatório , Alimentos Marinhos/parasitologia , Infecções por Trematódeos/parasitologia , Transtornos da Visão/veterinária
17.
Res Vet Sci ; 128: 1-8, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31706217

RESUMO

The aim of this work was to identify the molecular characteristics of a chymotrypsin-like enzyme from Trichinella spiralis (Tschy) and its facilitation of larval penetration into enteral epithelial cells (EECs). The complete Tschy cDNA sequence was cloned and expressed in Escherichia coli BL21. RT-PCR, IIFA and western blotting showed that Tschy was expressed at the T. spiralis muscle larvae (ML), intestinal infective L1 larvae (IL1), adult worms (AW) and embryo stages and was primarily located in the stichosome of this parasite. The results of ELISA, IIFA and Far-western assays showed that there was a specific binding between rTschy and EECs, and the binding was dependent on the dose of both rTschy and EEC proteins. Confocal microscopy demonstrated that the binding was located in the EEC cytoplasm. rTschy facilitated T. spiralis larval penetration of EECs, and anti-rTschy antibodies impeded the larval intrusion of EECs. These results demonstrate that Tschy facilitated the larval intrusion of the host's enteral epithelium and could be a candidate molecular target for vaccine against the enteral invasive phase of T. spiralis.


Assuntos
Quimotripsina/genética , Expressão Gênica , Proteínas de Helminto/genética , Interações Hospedeiro-Parasita/fisiologia , Trichinella spiralis/fisiologia , Animais , Quimotripsina/metabolismo , Embrião não Mamífero/enzimologia , Embrião não Mamífero/fisiologia , Células Epiteliais/parasitologia , Escherichia coli/genética , Proteínas de Helminto/metabolismo , Intestino Delgado/parasitologia , Larva/enzimologia , Larva/genética , Larva/crescimento & desenvolvimento , Larva/fisiologia , Microrganismos Geneticamente Modificados/genética , Trichinella spiralis/enzimologia , Trichinella spiralis/genética , Trichinella spiralis/crescimento & desenvolvimento , Vacinas/análise
18.
Parasitol Res ; 119(2): 559-566, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31786698

RESUMO

Parasitoid wasps may act as hyperparasites and sometimes regulate the populations of their hosts by a top-down dynamic. Nasonia vitripennis (Walker, 1836) is a generalist gregarious parasitoid that parasitizes several host flies, including the blowfly Protocalliphora Hough, 1899 (Diptera, Calliphoridae), which in turn parasitizes bird nestlings. Nonetheless, the ecological factors underlying N. vitripennis prevalence and parasitoidism intensity on its hosts in natural populations are poorly understood. We have studied the prevalence of N. vitripennis in Protocalliphora azurea (Fallén, 1817) puparia parasitizing wild populations of pied flycatcher (Ficedula hypoleuca) and blue tit (Cyanistes caeruleus) birds in two Mediterranean areas in central and southern Spain. We found some evidence that the prevalence of N. vitripennis was higher in moist habitats in southern Spain. A host-dependent effect was found, since the greater the number of P. azurea puparia, the greater the probability and rate of parasitoidism by the wasp. Our results also suggest that N. vitripennis parasitizes more P. azurea puparia in blue tit nests than in pied flycatcher nests as a consequence of a higher load of these flies in the former. Based on the high prevalence of N. vitripennis in P. azurea puparia in nature, we propose that this wasp may regulate blowfly populations, with possible positive effects on the reproduction of both bird species.


Assuntos
Aves/parasitologia , Dípteros/parasitologia , Vespas/fisiologia , Animais , Interações Hospedeiro-Parasita/fisiologia , Espanha
19.
Proc Natl Acad Sci U S A ; 117(1): 271-277, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31848246

RESUMO

Brown planthopper (BPH) is one of the most destructive insects affecting rice (Oryza sativa L.) production. Phenylalanine ammonia-lyase (PAL) is a key enzyme involved in plant defense against pathogens, but the role of PAL in insect resistance is still poorly understood. Here we show that expression of the majority of PALs in rice is significantly induced by BPH feeding. Knockdown of OsPALs significantly reduces BPH resistance, whereas overexpression of OsPAL8 in a susceptible rice cultivar significantly enhances its BPH resistance. We found that OsPALs mediate resistance to BPH by regulating the biosynthesis and accumulation of salicylic acid and lignin. Furthermore, we show that expression of OsPAL6 and OsPAL8 in response to BPH attack is directly up-regulated by OsMYB30, an R2R3 MYB transcription factor. Taken together, our results demonstrate that the phenylpropanoid pathway plays an important role in BPH resistance response, and provide valuable targets for genetic improvement of BPH resistance in rice.


Assuntos
Hemípteros/efeitos dos fármacos , Oryza/enzimologia , Oryza/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Fenilalanina Amônia-Liase/farmacologia , Doenças das Plantas/imunologia , Fatores de Transcrição/metabolismo , Animais , DNA de Plantas/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Técnicas de Silenciamento de Genes , Genes de Plantas , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Lignina/metabolismo , Oryza/genética , Oryza/imunologia , Fenilalanina Amônia-Liase/genética , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Ácido Salicílico/metabolismo
20.
Plant Biol (Stuttg) ; 22 Suppl 1: 84-92, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30779291

RESUMO

Increasing nitrogen deposition and more frequent drought events are likely to change plant interactions in natural grasslands. Both factors may also influence the interactions between hemiparasitic plants, regarded as keystone species in many grasslands, and their host species. We grew a combination of three suitable hosts, a grass, a forb and a legume, with and without the hemiparasite Rhinanthus alectorolophus at three levels of nitrogen (N) and two levels of water availability in a factorial design. Biomass of the hemiparasite and host community increased with N level and was reduced by drought to a similar degree. Larger plants in fertilised pots started to wilt earlier, and the presence of a hemiparasite further increased drought sensitivity. The hemiparasite strongly reduced biomass of the host community and overall productivity, and affected the competitive balance among host plants because it particularly reduced biomass of the dominant grass. These effects were the opposite of those of high N. The hemiparasite increased the root mass fraction of the hosts at all levels of N and water availability, indicating that the effect of the hemiparasite on the hosts was mainly due to loss of belowground resources. Our results indicate that hemiparasites will not always respond more strongly to increased N availability and drought than autotrophic plants, and that hemiparasites can have similarly strong effects on grassland communities as soil fertility and drought. By preferentially attacking dominant species the hemiparasites might alleviate the negative effects of nutrient enrichment on grassland diversity.


Assuntos
Secas , Interações Hospedeiro-Parasita , Nitrogênio , Orobanchaceae , Raízes de Plantas , Biomassa , Especificidade de Hospedeiro , Interações Hospedeiro-Parasita/efeitos dos fármacos , Interações Hospedeiro-Parasita/fisiologia , Nitrogênio/metabolismo , Nitrogênio/farmacologia , Orobanchaceae/efeitos dos fármacos , Orobanchaceae/fisiologia , Raízes de Plantas/parasitologia , Solo/química
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