Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22.998
Filtrar
1.
Zootaxa ; 4805(1): zootaxa.4805.1.1, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33056000

RESUMO

A systematic revision of the scale mites of the genus Pterygosoma (Acariformes: Pterygosomatidae) associated with agamas (Reptilia: Agamidae) was carried out based on type-material and numerous samples collected all over the world. For the natural species groups established in Fajfer (2019) diagnoses are presented. All Pterygosoma species are re-diagnosed or redescribed with simultaneous re-examination of host-parasite associations. Several taxonomic changes are implemented in the course of re-examination of the type series: seven subspecies of the genus Pterygosoma are elevated to species rank (with their former stem species in parentheses): P. aculeatum Lawrence, 1936 (agamae), P. angolae Jack, 1962 (melanum), P. capensis Jack, 1962 (melanum), P. longipalpae Lawrence, 1936 (melanum), P. orbicularis Jack, 1962 (spinosa) and P. pseudorbicularis Jack, 1962 (bibronii), P. problematica Jack, 1962 (fimbriata); four species are synonymized: Pterygosoma expansum Bertrand, Finkelman and Paperna, 2000 is synonymized with P. adramitana Jack, 1961 and consequently P. gladiator Bertrand, Finkelman and Paperna, 2000 with P. neumanni (Berlese, 1910), P. rhipidostichata Bertrand, Finkelman and Paperna, 2000 with P. mutabilis Jack, 1961 and P. livingstonei Bertrand and Modry, 2004 with P. circularis Jack, 1962; new hosts and distribution records are given for Pterygosoma neumanni (Berlese, 1910), P. bibronii Jack, 1962, P. longipalpae Lawrence, 1936, P. gracilipalpis and P. sinaita Jack, 1961. The protonymphs of Pterygosoma engai Fajfer, 2013, P. indare Fajfer, 2013, P. longipalpae Lawrence, 1936, and the deutonymph of P. transvaalense Lawrence, 1936 are described for the first time. A revision of leg chaetotaxy models i.e. coxae-trochanters I-IV and tarsi I-IV proposed by Jack (1964) is conducted and new species groups for Pterygosoma species are proposed. A key to all Pterygosoma species is provided. A full list of Pterygosoma species with their corrected host associations and distribution data is compiled.


Assuntos
Lagartos , Ácaros , Animais , Interações Hospedeiro-Parasita
2.
Korean J Parasitol ; 58(4): 373-386, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32871631

RESUMO

Fish-borne heterophyid trematodes are known to have a zoonotic potential, since at least 30 species are able to infect humans worldwide, with a global infection of around 7 million people. In this paper, a 'state-of-the-art' review of the South American heterophyid species is provided, including classical and molecular taxonomy, parasite ecology, host-parasite interaction studies and a list of species and their hosts. There is still a lack of information on human infections in South America with undetected or unreported infections probably due to the information shortage and little attention by physicians to these small intestinal flukes. Molecular tools for specific diagnoses of South American heterophyid species are still to be defined. Additional new sequences of Pygidiopsis macrostomum, Ascocotyle pindoramensis and Ascocotyle longa from Brazil are also provided.


Assuntos
Heterophyidae , Animais , Cianobactérias , DNA de Helmintos/genética , Peixes/parasitologia , Heterophyidae/classificação , Heterophyidae/genética , Heterophyidae/patogenicidade , Interações Hospedeiro-Parasita , Humanos , Análise de Sequência de DNA , América do Sul , Infecções por Trematódeos/parasitologia
3.
Korean J Parasitol ; 58(4): 461-466, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32871641

RESUMO

Toxoplasma gondii is an obligate intracellular protozoan parasite that can invade various organs in the host body, including the central nervous system. Chronic intracranial T. gondii is known to be associated with neuroprotection against neurodegenerative diseases through interaction with host brain cells in various ways. The present study investigated the neuroprotective effects of chronic T. gondii infection in mice with cerebral ischemia experimentally produced by middle cerebral artery occlusion (MCAO) surgery. The neurobehavioral effects of cerebral ischemia were assessed by measurement of Garcia score and Rotarod behavior tests. The volume of brain ischemia was measured by triphenyltetrazolium chloride staining. The expression levels of related genes and proteins were determined. After cerebral ischemia, corrected infarction volume was significantly reduced in T. gondii infected mice, and their neurobehavioral function was significantly better than that of the uninfection control group. Chronic T. gondii infection induced the expression of hypoxia-inducible factor 1-alpha (HIF-1α) in the brain before MCAO. T. gondii infection also increased the expression of vascular endothelial growth factor after the cerebral ischemia. It is suggested that chronic intracerebral infection of T. gondii may be a potential preconditioning strategy to reduce neural deficits associated with cerebral ischemia and induce brain ischemic tolerance through the regulation of HIF-1α expression.


Assuntos
Isquemia Encefálica/prevenção & controle , Encéfalo/parasitologia , Interações Hospedeiro-Parasita , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Neuroproteção , Toxoplasma/fisiologia , Toxoplasmose/fisiopatologia , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Encéfalo/patologia , Isquemia Encefálica/parasitologia , Isquemia Encefálica/patologia , Modelos Animais de Doenças , Expressão Gênica , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Camundongos Endogâmicos ICR , Tamanho do Órgão , Toxoplasmose/metabolismo , Toxoplasmose/patologia
4.
Nat Commun ; 11(1): 4483, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32900993

RESUMO

The Drosophila lymph gland, the larval hematopoietic organ comprised of prohemocytes and mature hemocytes, has been a valuable model for understanding mechanisms underlying hematopoiesis and immunity. Three types of mature hemocytes have been characterized in the lymph gland: plasmatocytes, lamellocytes, and crystal cells, which are analogous to vertebrate myeloid cells, yet molecular underpinnings of the lymph gland hemocytes have been less investigated. Here, we use single-cell RNA sequencing to comprehensively analyze heterogeneity of developing hemocytes in the lymph gland, and discover previously undescribed hemocyte types including adipohemocytes, stem-like prohemocytes, and intermediate prohemocytes. Additionally, we identify the developmental trajectory of hemocytes during normal development as well as the emergence of the lamellocyte lineage following active cellular immunity caused by wasp infestation. Finally, we establish similarities and differences between embryonically derived- and larval lymph gland hemocytes. Altogether, our study provides detailed insights into the hemocyte development and cellular immune responses at single-cell resolution.


Assuntos
Drosophila melanogaster/citologia , Drosophila melanogaster/genética , Hemócitos/citologia , Hemócitos/metabolismo , Transcriptoma , Animais , Animais Geneticamente Modificados , Diferenciação Celular/genética , Linhagem da Célula/genética , Drosophila melanogaster/metabolismo , Ectoparasitoses/genética , Ectoparasitoses/metabolismo , Ectoparasitoses/patologia , Perfilação da Expressão Gênica , Hematopoese/genética , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Tecido Linfoide/citologia , Tecido Linfoide/metabolismo , Tecido Linfoide/parasitologia , RNA-Seq , Análise de Célula Única , Vespas/patogenicidade
5.
Nat Commun ; 11(1): 4393, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32879321

RESUMO

Rcr3 is a secreted protease of tomato that is targeted by fungal effector Avr2, a secreted protease inhibitor of the fungal pathogen Cladosporium fulvum. The Avr2-Rcr3 complex is recognized by receptor-like protein Cf-2, triggering hypersensitive cell death (HR) and disease resistance. Avr2 also targets Rcr3 paralog Pip1, which is not required for Avr2 recognition but contributes to basal resistance. Thus, Rcr3 acts as a guarded decoy in this interaction, trapping the fungus into a recognition event. Here we show that Rcr3 evolved > 50 million years ago (Mya), whereas Cf-2 evolved <6Mya by co-opting the pre-existing Rcr3 in the Solanum genus. Ancient Rcr3 homologs present in tomato, potato, eggplants, pepper, petunia and tobacco can be inhibited by Avr2 with the exception of tobacco Rcr3. Four variant residues in Rcr3 promote Avr2 inhibition, but the Rcr3 that co-evolved with Cf-2 lacks three of these residues, indicating that the Rcr3 co-receptor is suboptimal for Avr2 binding. Pepper Rcr3 triggers HR with Cf-2 and Avr2 when engineered for enhanced inhibition by Avr2. Nicotiana benthamiana (Nb) is a natural null mutant carrying Rcr3 and Pip1 alleles with deleterious frame-shift mutations. Resurrected NbRcr3 and NbPip1 alleles were active proteases and further NbRcr3 engineering facilitated Avr2 inhibition, uncoupled from HR signalling. The evolution of a receptor co-opting a conserved pathogen target contrasts with other indirect pathogen recognition mechanisms.


Assuntos
Cladosporium , Resistência à Doença/genética , Peptídeo Hidrolases/genética , Imunidade Vegetal/genética , Solanum , Tabaco , Cladosporium/genética , Cladosporium/metabolismo , Cladosporium/patogenicidade , Evolução Molecular , Proteínas Fúngicas/metabolismo , Genes de Plantas , Interações Hospedeiro-Parasita , Peptídeo Hidrolases/metabolismo , Filogenia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Inibidores de Proteases/metabolismo , Solanum/genética , Solanum/metabolismo , Solanum/microbiologia , Tabaco/genética , Tabaco/metabolismo , Tabaco/microbiologia
6.
PLoS Pathog ; 16(9): e1008739, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32946522

RESUMO

Malaria-causing Plasmodium parasites traverse the mosquito midgut cells to establish infection at the basal side of the midgut. This dynamic process is a determinant of mosquito vector competence, yet the kinetics of the parasite migration is not well understood. Here we used transgenic mosquitoes of two Anopheles species and a Plasmodium berghei fluorescence reporter line to track parasite passage through the mosquito tissues at high spatial resolution. We provide new quantitative insight into malaria parasite invasion in African and Indian Anopheles species and propose that the mosquito complement-like system contributes to the species-specific dynamics of Plasmodium invasion.


Assuntos
Anopheles/parasitologia , Sistema Digestório/parasitologia , Interações Hospedeiro-Parasita , Malária/transmissão , Mosquitos Vetores/patogenicidade , Plasmodium berghei/fisiologia , Animais , Anopheles/crescimento & desenvolvimento , Feminino , Malária/parasitologia , Camundongos , Especificidade da Espécie
7.
Oecologia ; 194(1-2): 65-74, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32876762

RESUMO

Parasites are ecologically ubiquitous and, by modifying the physiology and behavior of their host organisms, act as key regulators of the dynamics and stability of ecosystems. It is, however, as yet unclear how parasitic relationships will act to moderate or accelerate the ecological impacts of global climate change. Here, we explore experimentally how the effects of parasites on both the physiology and behavior of their hosts can be moderated by warming, utilising a well-established aquatic host-parasite model system-the ecologically important amphipod Gammarus duebeni and its acanthocephalan parasite Polymorphus minutus. We show that, while only warming affected measured components of host physiology, parasite infection and warming both supressed predator-avoidance behavior of the host independently, yet in a similar manner. Six degrees of warming altered geotactic behaviors to the same extent as infection with behavior-manipulating parasites. These results indicate a novel mechanism by which parasites impact their ecosystems that could be critical to predicting the ecological impacts of warming. Our findings highlight the need for holistic knowledge of interaction networks, incorporating multiple interaction types and behaviors, to predict the effects of both warming and parasitism on the dynamics and stability of ecosystems.


Assuntos
Acantocéfalos , Anfípodes , Infecções , Parasitos , Animais , Ecossistema , Interações Hospedeiro-Parasita
8.
PLoS One ; 15(9): e0237322, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881929

RESUMO

A bite from a La Crosse virus (LACV) infected Aedes mosquito can cause La Crosse encephalitis (LACE), which is a neuro-invasive disease that disproportionately affects children under the age of 16 in Southern Appalachia. The three vectors for LACV are Aedes albopictus (Skuse), Ae. japonicus (Theobald), and Ae. triseriatus (Say). Localized maps of the geographic distribution of vectors are practical tools for mosquito management personnel to target areas with high mosquito abundance. This study hypothesized that LACV vectors have unique species-specific spatial and temporal clusters. To test this, 44 sites were identified in Knox County, Tennessee for their land use/type. At each site, host-seeking mosquitoes were collected approximately every other week from May-October 2018. Spatial clusters of host-seeking mosquito collections for each of the three mosquito species were investigated using Kulldorff's spatial scan statistic, specifying a retrospective space-time Bernoulli model. Most vector clusters were identified in south-central Knox County while the seasonality of clusters varied by mosquito species. Clusters of Ae. albopictus were observed throughout the entire study period while clusters of Ae. japonicus and Ae. triseriatus only occurred May-June. The findings indicate that the relative abundance of LACV vectors were more abundant in south-central Knox County compared to the rest of the county. Of interest, these clusters spatially overlapped with previous LACE diagnosed cases. These findings are useful in guiding decisions on targeted mosquito control in Knox County and may be applied to other counties within Southern Appalachia.


Assuntos
Aedes/virologia , Comportamento Animal , Doenças Endêmicas , Interações Hospedeiro-Parasita , Vírus La Crosse/fisiologia , Análise Espaço-Temporal , Animais , Geografia , Insetos Vetores/virologia , Tennessee
9.
PLoS Biol ; 18(9): e3000828, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32936797

RESUMO

Many herbivorous insects are mono- or oligophagous, having evolved to select a limited range of host plants. They specifically identify host-plant leaves using their keen sense of taste. Plant secondary metabolites and sugars are thought to be key chemical cues that enable insects to identify host plants and evaluate their quality as food. However, the neuronal and behavioral mechanisms of host-plant recognition are poorly understood. Here, we report a two-factor host acceptance system in larvae of the silkworm Bombyx mori, a specialist on several mulberry species. The first step is controlled by a chemosensory organ, the maxillary palp (MP). During palpation at the leaf edge, the MP detects trace amounts of leaf-surface compounds, which enables host-plant recognition without biting. Chemosensory neurons in the MP are tuned with ultrahigh sensitivity (thresholds of attomolar to femtomolar) to chlorogenic acid (CGA), quercetin glycosides, and ß-sitosterol (ßsito). Only if these 3 compounds are detected does the larva make a test bite, which is evaluated in the second step. Low-sensitivity neurons in another chemosensory organ, the maxillary galea (MG), mainly detect sucrose in the leaf sap exuded by test biting, allowing larvae to accept the leaf and proceed to persistent biting (feeding). The two-factor host acceptance system reported here may commonly underlie stereotyped feeding behavior in many phytophagous insects and determine their feeding habits.


Assuntos
Bombyx/fisiologia , Comportamento de Escolha , Dieta , Comportamento Alimentar/fisiologia , Larva/fisiologia , Papilas Gustativas/fisiologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Comportamento Animal/fisiologia , Bombyx/anatomia & histologia , Bombyx/crescimento & desenvolvimento , Células Quimiorreceptoras/fisiologia , Quimiotaxia/fisiologia , Sinais (Psicologia) , Comportamento Exploratório/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Larva/anatomia & histologia , Larva/citologia , Morus/química , Folhas de Planta/química , Paladar/fisiologia , Papilas Gustativas/anatomia & histologia
10.
Annu Rev Phytopathol ; 58: 1-22, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32853101

RESUMO

Gall-inducing insects and nematodes engage in sophisticated interactions with their host plants. These parasites can induce major morphological and physiological changes in host roots, leaves, and other tissues. Sedentary endoparasitic nematodes, root-knot and cyst nematodes in particular, as well as gall-inducing and leaf-mining insects, manipulate plant development to form unique organs that provide them with food from feeding cells. Sometimes, infected tissues may undergo a developmental switch resulting in the formation of aberrant and spectacular structures (clubs or galls). We describe here the complex interactions between these plant-reprogramming sedentary endoparasites and their infected hosts, focusing on similarities between strategies of plant manipulation. We highlight progress in our understanding of the host plant response to infection and focus on the nematode and insect molecules secreted in planta. We suggest thatlooking at similarities may identify convergent and conserved strategies and shed light on the promise they hold for the development of new management strategies in agriculture and forestry.


Assuntos
Parasitos , Tylenchoidea , Animais , Interações Hospedeiro-Parasita , Insetos , Doenças das Plantas , Raízes de Plantas , Plantas
11.
Nat Commun ; 11(1): 4185, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826898

RESUMO

Adaptive responses to ecological uncertainty may affect the dynamics of interspecific interactions and shape the course of evolution within symbioses. Obligate avian brood parasites provide a particularly tractable system for understanding how uncertainty, driven by environmental variability and symbiont phenology, influences the evolution of species interactions. Here, we use phylogenetically-informed analyses and a comprehensive dataset on the behaviour and geographic distribution of obligate avian brood parasites and their hosts to demonstrate that increasing uncertainty in thermoregulation and parental investment of parasitic young are positively associated with host richness and diversity. Our findings are consistent with the theoretical expectation that ecological risks and environmental unpredictability should favour the evolution of bet-hedging. Additionally, these highly consistent patterns highlight the important role that ecological uncertainty is likely to play in shaping the evolution of specialisation and generalism in complex interspecific relationships.


Assuntos
Aves/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Parasitos/fisiologia , Incerteza , Animais , Biodiversidade , Coevolução Biológica , Aves/classificação , Clima , Comportamento de Nidação , Parasitos/classificação , Filogenia , Fatores de Risco , Especificidade da Espécie
12.
PLoS Biol ; 18(8): e3000830, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810128

RESUMO

Plants are attacked by herbivores, which often specialize on different tissues, and in response, have evolved sophisticated resistance strategies that involve different types of chemical defenses frequently targeted to different tissues. Most known phytohormones have been implicated in regulating these defenses, with jasmonates (JAs) playing a pivotal role in complex regulatory networks of signaling interactions, often generically referred to as "cross talk." The newly identified class of phytohormones, strigolactones (SLs), known to regulate the shoot architecture, remain unstudied with regard to plant-herbivore interactions. We explored the role of SL signaling in resistance to a specialist weevil (Trichobaris mucorea) herbivore of the native tobacco, Nicotiana attenuata, that attacks the root-shoot junction (RSJ), the part of the plant most strongly influenced by alterations in SL signaling (increased branching). As SL signaling shares molecular components, such as the core F-box protein MORE AXILLARY GROWTH 2 (MAX2), with another new class of phytohormones, the karrikins (KARs), which promote seed germination and seedling growth, we generated transformed lines, individually silenced in the expression of NaMAX2, DWARF 14 (NaD14: the receptor for SL) and CAROTENOID CLEAVAGE DIOXYGENASE 7 (NaCCD7: a key enzyme in SL biosynthesis), and KARRIKIN INSENSITIVE 2 (NaKAI2: the KAR receptor). The mature stems of all transgenic lines impaired in the SL, but not the KAR signaling pathway, overaccumulated anthocyanins, as did the stems of plants attacked by the larvae of weevil, which burrow into the RSJs to feed on the pith of N. attenuata stems. T. mucorea larvae grew larger in the plants silenced in the SL pathway, but again, not in the KAI2-silenced plants. These phenotypes were associated with elevated JA and auxin (indole-3-acetic acid [IAA]) levels and significant changes in the accumulation of defensive compounds, including phenolamides and nicotine. The overaccumulation of phenolamides and anthocyanins in the SL pathway-silenced plants likely resulted from antagonism between the SL and JA pathway in N. attenuata. We show that the repressors of SL signaling, suppressor of max2-like (NaSMXL6/7), and JA signaling, jasmonate zim-domain (NaJAZs), physically interact, promoting NaJAZb degradation and releasing JASMONATE INSENSITIVE 1 (JIN1/MYC2) (NaMYC2), a critical transcription factor promoting JA responses. However, the increased performance of T. mucorea larvae resulted from lower pith nicotine levels, which were inhibited by increased IAA levels in SL pathway-silenced plants. This inference was confirmed by decapitation and auxin transport inhibitor treatments that decreased pith IAA and increased nicotine levels. In summary, SL signaling tunes specific sectors of specialized metabolism in stems, such as phenylpropanoid and nicotine biosynthesis, by tailoring the cross talk among phytohormones, including JA and IAA, to mediate herbivore resistance of stems. The metabolic consequences of the interplay of SL, JA, and IAA signaling revealed here could provide a mechanism for the commonly observed pattern of herbivore tolerance/resistance trade-offs.


Assuntos
Herbivoria/fisiologia , Interações Hospedeiro-Parasita , Lactonas/metabolismo , Caules de Planta/metabolismo , Caules de Planta/parasitologia , Transdução de Sinais , Tabaco/metabolismo , Tabaco/parasitologia , Animais , Antocianinas/metabolismo , Ciclopentanos/metabolismo , Ácidos Indolacéticos/metabolismo , Larva , Metabolômica , Oxilipinas/metabolismo , Proteínas de Plantas/metabolismo , Interferência de RNA , Gorgulhos/fisiologia
13.
PLoS One ; 15(8): e0229277, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817698

RESUMO

Human activities are changing landscape structure and function globally, affecting wildlife space use, and ultimately increasing human-wildlife conflicts and zoonotic disease spread. Capybaras (Hydrochoerus hydrochaeris) are linked to conflicts in human-modified landscapes (e.g. crop damage, vehicle collision), as well as the spread and amplification of Brazilian spotted fever (BSF), the most human-lethal tick-borne disease in the world. Even though it is essential to understand the link between capybaras, ticks and BSF, many knowledge gaps still exist regarding the effects of human disturbance in capybara space use. Here, we analyzed diurnal and nocturnal habitat selection strategies of capybaras across natural and human-modified landscapes using resource selection functions (RSF). Selection for forested habitats was higher across human-modified landscapes, mainly during day- periods, when compared to natural landscapes. Across natural landscapes, capybaras avoided forests during both day- and night periods. Water was consistently selected across both landscapes, during day- and nighttime. Distance to water was also the most important variable in predicting capybara habitat selection across natural landscapes. Capybaras showed slightly higher preferences for areas near grasses/shrubs across natural landscapes, and distance to grasses/shrubs was the most important variable in predicting capybara habitat selection across human-modified landscapes. Our results demonstrate human-driven variation in habitat selection strategies by capybaras. This behavioral adjustment across human-modified landscapes may be related to increases in A. sculptum density, ultimately affecting BSF.


Assuntos
Ecossistema , Roedores/psicologia , Animais , Animais Selvagens , Brasil , Meio Ambiente , Pradaria , Interações Hospedeiro-Parasita/fisiologia , Humanos , Febre Maculosa das Montanhas Rochosas/epidemiologia , Carrapatos , Água , Zoonoses
14.
Nat Commun ; 11(1): 4015, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32782246

RESUMO

Intracellular pathogens mobilize host signaling pathways of their host cell to promote their own survival. Evidence is emerging that signal transduction elements are activated in a-nucleated erythrocytes in response to infection with malaria parasites, but the extent of this phenomenon remains unknown. Here, we fill this knowledge gap through a comprehensive and dynamic assessment of host erythrocyte signaling during infection with Plasmodium falciparum. We used arrays of 878 antibodies directed against human signaling proteins to interrogate the activation status of host erythrocyte phospho-signaling pathways at three blood stages of parasite asexual development. This analysis reveals a dynamic modulation of many host signalling proteins across parasite development. Here we focus on the hepatocyte growth factor receptor (c-MET) and the MAP kinase pathway component B-Raf, providing a proof of concept that human signaling kinases identified as activated by malaria infection represent attractive targets for antimalarial intervention.


Assuntos
Antimaláricos/farmacologia , Eritrócitos/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais , Eritrócitos/parasitologia , Interações Hospedeiro-Parasita , Humanos , Concentração Inibidora 50 , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Fosforilação/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/metabolismo , Plasmodium falciparum/fisiologia , Análise Serial de Proteínas , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Proteínas Proto-Oncogênicas B-raf/metabolismo , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/metabolismo , Transdução de Sinais/efeitos dos fármacos
15.
Nat Commun ; 11(1): 3825, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32732874

RESUMO

The malaria parasite interfaces with its host erythrocyte (RBC) using a unique organelle, the parasitophorous vacuole (PV). The mechanism(s) are obscure by which its limiting membrane, the parasitophorous vacuolar membrane (PVM), collaborates with the parasite plasma membrane (PPM) to support the transport of proteins, lipids, nutrients, and metabolites between the cytoplasm of the parasite and the cytoplasm of the RBC. Here, we demonstrate that the PV has structure characterized by micrometer-sized regions of especially close apposition between the PVM and the PPM. To determine if these contact sites are involved in any sort of transport, we localize the PVM nutrient-permeable and protein export channel EXP2, as well as the PPM lipid transporter PfNCR1. We find that EXP2 is excluded from, but PfNCR1 is included within these regions of close apposition. We conclude that the host-parasite interface is structured to segregate those transporters of hydrophilic and hydrophobic substrates.


Assuntos
Lipídeos , Malária Falciparum/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Transporte Biológico , Membrana Celular/metabolismo , Citoplasma/metabolismo , Citoplasma/parasitologia , Eritrócitos/metabolismo , Eritrócitos/parasitologia , Interações Hospedeiro-Parasita , Humanos , Membranas Intracelulares/metabolismo , Membranas Intracelulares/parasitologia , Malária Falciparum/parasitologia , Plasmodium falciparum/fisiologia , Transporte Proteico , Vacúolos/metabolismo , Vacúolos/parasitologia
16.
An Acad Bras Cienc ; 92(2): e20181115, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785425

RESUMO

We surveyed 58 scientific articles published between 1987 and 2018 to evaluate the representative nature of the Fabaceae as hosts of insect galls in Brazil, and to gain a better understanding of the interactions between gall-inducing insects and plants and the evolutionary ecology of those insects and their plant hosts. A total of 438 gall morphotypes were reported as being generated by gall-inducing insects on 178 Fabaceae host species belonging to five subfamilies Caesalpinioideae (22 genera and 79 spp.), Cercidoideae (1 genus and 11 spp.), Detarioideae (6 genera and 17 spp.), Dialioideae (2 genera and 2 spp.), and Papilionoideae (26 genera and 69 spp.). The plant host genera demonstrating the greatest richness of gall-inducing insects were Inga, Bauhinia, and Copaifera; the super-host species were Copaifera langsdorffii, Bauhinia brevipes, and Copaifera sabulicola. Most of the galls were observed on leaves; they were mostly globoid, green, glabrous, isolated, and unilocular. The principal gall inducers belonged to Cecidomyiidae; the associated fauna was represented by Collembola, Coleoptera, Diptera, Formicidae, Hemiptera, Hymenoptera, Lepidoptera, Pseudoscorpionida, and Thysanoptera. Fabaceae are the principal super-hosts of galls and one of the most diverse families of angiosperms in Brazil, aggregating evidences for the hypotheses of floristic richness and taxon size.


Assuntos
Fabaceae , Animais , Brasil , Interações Hospedeiro-Parasita , Insetos , Tumores de Planta
17.
Proc Natl Acad Sci U S A ; 117(32): 19299-19309, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32737161

RESUMO

Schistosomes are parasitic flatworms that cause schistosomiasis, a neglected tropical disease affecting over 200 million people. Schistosomes develop multiple body plans while navigating their complex life cycle, which involves two different hosts: a mammalian definitive host and a molluscan intermediate host. Their survival and propagation depend upon proliferation and differentiation of stem cells necessary for parasite homeostasis and reproduction. Infective larvae released from snails carry a handful of stem cells that serve as the likely source of new tissues as the parasite adapts to life inside the mammalian host; however, the role of these stem cells during this critical life cycle stage remains unclear. Here, we characterize stem cell fates during early intramammalian development. Surprisingly, we find that the esophageal gland, an accessory organ of the digestive tract, develops before the rest of the digestive system is formed and blood feeding is initiated, suggesting a role in processes beyond nutrient uptake. To explore such a role, we examine schistosomes that lack the esophageal gland due to knockdown of a forkhead-box transcription factor, Sm-foxA, which blocks development and maintenance of the esophageal gland, without affecting the development of other somatic tissues. Intriguingly, schistosomes lacking the esophageal gland die after transplantation into naive mice, but survive in immunodeficient mice lacking B cells. We show that parasites lacking the esophageal gland are unable to lyse ingested immune cells within the esophagus before passing them into the gut. These results unveil an immune-evasion mechanism mediated by the esophageal gland, which is essential for schistosome survival and pathogenesis.


Assuntos
Esôfago/parasitologia , Evasão da Resposta Imune , Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Animais , Esôfago/imunologia , Feminino , Proteínas de Helminto/genética , Proteínas de Helminto/imunologia , Interações Hospedeiro-Parasita , Humanos , Estágios do Ciclo de Vida , Masculino , Camundongos , Schistosoma mansoni/genética , Schistosoma mansoni/crescimento & desenvolvimento , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/fisiopatologia
18.
Parasitol Res ; 119(9): 2917-2925, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32734308

RESUMO

Trematode-induced castration of snails is widespread and can lead to other life history changes of snails such as changes in trajectories of size and growth or survival. The changes produced likely depend on whether the parasite or host controls allocation of host resources remaining after partial or complete cessation of host current reproduction by castrating trematodes. Documenting host life history changes, like changes in host size in response to castration, is a first step in assessing whether these changes are beneficial to the parasite (increasing transmission success) or to the host (outliving the infection) or to neither. Herein, we test for differences in size and survival among individuals of two snail species in relation to infection by Echinostoma spp. trematodes. Active shedding of Echinostoma spp. was associated with castration of all Stagnicola elodes snails from a site in Eastern Ontario. Snails actively shedding cercariae were not different in size from non-shedding, egg-laying snails but had a higher mortality than egg-laying snails. Active shedding of Echinostoma spp. cercariae was also associated with castration of nearly all Helisoma trivolvis monitored, from a site in Southwestern Ontario. Actively shedding, non-laying H. trivolvis hosts were smaller on average than non-shedding egg-laying hosts, but both non-laying and egg-laying snails survived equally well. We discuss these results in light of what is known about effects of castration on snail hosts in terms of growth and survival for these and other trematode species and speculate on whether changes in size or survival benefits parasite or host.


Assuntos
Castração , Cercárias/crescimento & desenvolvimento , Echinostoma/crescimento & desenvolvimento , Lymnaea/parasitologia , Oviposição/fisiologia , Animais , Alimentos , Água Doce , Interações Hospedeiro-Parasita , Ontário , Reprodução
19.
Nat Commun ; 11(1): 3922, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764664

RESUMO

The Plasmodium falciparum chloroquine resistance transporter (PfCRT) is a key contributor to multidrug resistance and is also essential for the survival of the malaria parasite, yet its natural function remains unresolved. We identify host-derived peptides of 4-11 residues, varying in both charge and composition, as the substrates of PfCRT in vitro and in situ, and show that PfCRT does not mediate the non-specific transport of other metabolites and/or ions. We find that drug-resistance-conferring mutations reduce both the peptide transport capacity and substrate range of PfCRT, explaining the impaired fitness of drug-resistant parasites. Our results indicate that PfCRT transports peptides from the lumen of the parasite's digestive vacuole to the cytosol, thereby providing a source of amino acids for parasite metabolism and preventing osmotic stress of this organelle. The resolution of PfCRT's native substrates will aid the development of drugs that target PfCRT and/or restore the efficacy of existing antimalarials.


Assuntos
Antimaláricos/farmacologia , Cloroquina/farmacologia , Proteínas de Membrana Transportadoras/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Animais , Transporte Biológico Ativo , Resistência a Medicamentos/genética , Feminino , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Proteínas de Membrana Transportadoras/genética , Modelos Biológicos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Oligopeptídeos/metabolismo , Oócitos/metabolismo , Plasmodium falciparum/genética , Transporte Proteico , Proteínas de Protozoários/genética , Xenopus laevis
20.
PLoS Negl Trop Dis ; 14(8): e0008533, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776937

RESUMO

Campylobacter is the leading bacterial cause of gastroenteritis worldwide and its incidence is especially high in low- and middle-income countries (LMIC). Disease epidemiology in LMICs is different compared to high income countries like the USA or in Europe. Children in LMICs commonly have repeated and chronic infections even in the absence of symptoms, which can lead to deficits in early childhood development. In this study, we sequenced and characterized C. jejuni (n = 62) from a longitudinal cohort study of children under the age of 5 with and without diarrheal symptoms, and contextualized them within a global C. jejuni genome collection. Epidemiological differences in disease presentation were reflected in the genomes, specifically by the absence of some of the most common global disease-causing lineages. As in many other countries, poultry-associated strains were likely a major source of human infection but almost half of local disease cases (15 of 31) were attributable to genotypes that are rare outside of Peru. Asymptomatic infection was not limited to a single (or few) human adapted lineages but resulted from phylogenetically divergent strains suggesting an important role for host factors in the cryptic epidemiology of campylobacteriosis in LMICs.


Assuntos
Infecções Assintomáticas , Infecções por Campylobacter/epidemiologia , Infecções por Campylobacter/microbiologia , Campylobacter jejuni/genética , Animais , Infecções por Campylobacter/diagnóstico , Infecções por Campylobacter/fisiopatologia , Campylobacter jejuni/classificação , Pré-Escolar , Estudos de Coortes , Diarreia/epidemiologia , Genômica , Genótipo , Interações Hospedeiro-Parasita , Humanos , Lactente , Recém-Nascido , Estudos Longitudinais , Tipagem Molecular , Tipagem de Sequências Multilocus , Peru/epidemiologia , Filogenia , Aves Domésticas/microbiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA