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2.
Int J Mol Sci ; 22(12)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204357

RESUMO

Heme biosynthesis is essential for almost all living organisms. Despite its conserved function, the pathway's enzymes can be located in a remarkable diversity of cellular compartments in different organisms. This location does not always reflect their evolutionary origins, as might be expected from the history of their acquisition through endosymbiosis. Instead, the final subcellular localization of the enzyme reflects multiple factors, including evolutionary origin, demand for the product, availability of the substrate, and mechanism of pathway regulation. The biosynthesis of heme in the apicomonad Chromera velia follows a chimeric pathway combining heme elements from the ancient algal symbiont and the host. Computational analyses using different algorithms predict complex targeting patterns, placing enzymes in the mitochondrion, plastid, endoplasmic reticulum, or the cytoplasm. We employed heterologous reporter gene expression in the apicomplexan parasite Toxoplasma gondii and the diatom Phaeodactylum tricornutum to experimentally test these predictions. 5-aminolevulinate synthase was located in the mitochondria in both transfection systems. In T. gondii, the two 5-aminolevulinate dehydratases were located in the cytosol, uroporphyrinogen synthase in the mitochondrion, and the two ferrochelatases in the plastid. In P. tricornutum, all remaining enzymes, from ALA-dehydratase to ferrochelatase, were placed either in the endoplasmic reticulum or in the periplastidial space.


Assuntos
Alveolados/fisiologia , Apicomplexa/metabolismo , Diatomáceas/metabolismo , Heme/metabolismo , Redes e Vias Metabólicas , Sequência de Aminoácidos , Transporte Biológico , Evolução Molecular , Regulação Enzimológica da Expressão Gênica , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo
3.
PLoS One ; 16(6): e0252514, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34061893

RESUMO

Most corals acquire symbiodiniacean symbionts from the surrounding environment to initiate symbiosis. The cell densities of Symbiodiniaceae in the environment are usually low, and mechanisms may exist by which new coral generations attract suitable endosymbionts. Phototaxis of suitable symbiodiniacean cells toward green fluorescence in corals has been proposed as one such mechanism. In the present study, we observed the phototaxis action wavelength of various strains of Symbiodiniaceae and the fluorescence spectra of aposymbiotic Acropora tenuis larvae at the time of endosymbiont uptake. The phototaxis patterns varied among the Symbiodiniaceae species and "native" endosymbionts-commonly found in Acropora juveniles present in natural environments; that is, Symbiodinium microadriaticum was attracted to blue light rather than to green light. Another native endosymbiont, Durusdinium trenchii, showed no phototaxis specific to any wavelength. Although the larvae exhibited green and broad orange fluorescence under blue-violet excitation light, the maximum green fluorescence peak did not coincide with that of the phototaxis action spectrum of S. microadriaticum. Rather, around the peak wavelength of larval green fluorescence, this native endosymbiont showed slightly negative phototaxis, suggesting that the green fluorescence of A. tenuis larvae may not play a role in the initial attraction of native endosymbionts. Conversely, broad blue larval fluorescence under UV-A excitation covered the maximum phototaxis action wavelength of S. microadriaticum. We also conducted infection tests using native endosymbionts and aposymbiotic larvae under red LED light that does not excite visible larval fluorescence. Almost all larvae failed to acquire S. microadriaticum cells, whereas D. trenchii cells were acquired by larvae even under red illumination. Thus, attraction mechanisms other than visible fluorescence might exist, at least in the case of D. trenchii. Our results suggest that further investigation and discussion, not limited to green fluorescence, would be required to elucidate the initial attraction mechanisms.


Assuntos
Alveolados/fisiologia , Antozoários/fisiologia , Fluorescência , Larva/fisiologia , Simbiose/fisiologia , Animais , Recifes de Corais , Dinoflagelados/fisiologia , Fototaxia/fisiologia , Raios Ultravioleta
4.
Sci Rep ; 11(1): 12872, 2021 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-34145372

RESUMO

The protozoan parasite Perkinsus marinus, which causes dermo disease in Crassostrea virginica, is one of the most ecologically important and economically destructive marine pathogens. The rapid and persistent intensification of dermo in the USA in the 1980s has long been enigmatic. Attributed originally to the effects of multi-year drought, climatic factors fail to fully explain the geographic extent of dermo's intensification or the persistence of its intensified activity. Here we show that emergence of a unique, hypervirulent P. marinus phenotype was associated with the increase in prevalence and intensity of this disease and associated mortality. Retrospective histopathology of 8355 archival oysters from 1960 to 2018 spanning Chesapeake Bay, South Carolina, and New Jersey revealed that a new parasite phenotype emerged between 1983 and 1990, concurrent with major historical dermo disease outbreaks. Phenotypic changes included a shortening of the parasite's life cycle and a tropism shift from deeper connective tissues to digestive epithelia. The changes are likely adaptive with regard to the reduced oyster abundance and longevity faced by P. marinus after rapid establishment of exotic pathogen Haplosporidium nelsoni in 1959. Our findings, we hypothesize, illustrate a novel ecosystem response to a marine parasite invasion: an increase in virulence in a native parasite.


Assuntos
Alveolados , Doenças dos Animais/patologia , Doenças dos Animais/parasitologia , Crassostrea/parasitologia , Interações Hospedeiro-Parasita , Animais , Fenótipo
5.
Mar Environ Res ; 169: 105344, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34015675

RESUMO

Data that can be used to monitor biodiversity through time are essential for conservation and management. The reef-forming worm, Sabellaria alveolata (L. 1767) is currently classed as 'Data Deficient' due to an imbalance in the spread of data on its distribution. Little is known about the distribution of this species around Ireland. Using data archaeology, we collated past and present distribution records and discovered that S. alveolata has a discontinuous distribution with large gaps between populations. Many regions lack data and should be targeted for sampling. Biodiversity surveys revealed that S. alveolata supported diverse epibiotic algal communities. Retrograding (declining) reefs supported greater infaunal diversity than prograding (growing) reefs or sand, suggesting that S. alveolata is a dynamic ecosystem engineer that has a lasting legacy effect. Similar research should be carried out for other Data Deficient species, habitats and regions. Such data are invaluable resources for management and conservation.


Assuntos
Alveolados , Poliquetos , Animais , Biodiversidade , Conservação dos Recursos Naturais , Recifes de Corais , Ecossistema , Irlanda
6.
PLoS One ; 16(5): e0251133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33956864

RESUMO

DNA transposons are defined as repeated DNA sequences that can move within the host genome through the action of transposases. The transposon superfamily Merlin was originally found mainly in animal genomes. Here, we describe a global distribution of the Merlin in animals, fungi, plants and protists, reporting for the first time their presence in Rhodophyceae, Metamonada, Discoba and Alveolata. We identified a great variety of potentially active Merlin families, some containing highly imperfect terminal inverted repeats and internal tandem repeats. Merlin-related sequences with no evidence of mobilization capacity were also observed and may be products of domestication. The evolutionary trees support that Merlin is likely an ancient superfamily, with early events of diversification and secondary losses, although repeated re-invasions probably occurred in some groups, which would explain its diversity and discontinuous distribution. We cannot rule out the possibility that the Merlin superfamily is the product of multiple horizontal transfers of related prokaryotic insertion sequences. Moreover, this is the first account of a DNA transposon in kinetoplastid flagellates, with conserved Merlin transposase identified in Bodo saltans and Perkinsela sp., whereas it is absent in trypanosomatids. Based on the level of conservation of the transposase and overlaps of putative open reading frames with Merlin, we propose that in protists it may serve as a raw material for gene emergence.


Assuntos
Elementos de DNA Transponíveis/genética , Eucariotos/genética , Kinetoplastida/genética , Neurofibromina 2/genética , Alveolados/genética , Evolução Molecular , Filogenia , Reação em Cadeia da Polimerase
7.
J Invertebr Pathol ; 184: 107603, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33971219

RESUMO

The aetiological agent Perkinsus olseni is globally recognised as a major threat for shellfish production considering its wide geographical distribution across Asia, Europe, Australia and South America. Another species, Perkinsus chesapeaki, which has never been known to be associated with significant mortality events, was recently detected along French coasts infecting clam populations sporadically in association with P. olseni. Identifying potential cryptic infections affecting Ruditapes philippinarum is essential to develop appropriate host resource management strategies. Here, we developed a molecular method based on duplex real-time quantitative PCR for the simultaneous detection of these two parasites, P. olseni and P. chesapeaki, in the different clam tissues: gills, digestive gland, foot, mantle, adductor muscle and the rest of the soft body. We firstly checked the presence of possible PCR inhibitors in host tissue samples. The qPCR reactions were inhibited depending on the nature of the host organ. The mantle and the rest of the soft body have a high inhibitory effect from threshold of host gDNA concentration of 2 ng.µL-1, the adductor muscle and the foot have an intermediate inhibition of 5 ng.µL-1, and the gills and digestive gland do not show any inhibition of the qPCR reaction even at the highest host gDNA concentration of 20 ng.µL-1. Then, using the gills as a template, the suitability of the molecular technique was checked in comparison with the Ray's Fluid Thioglycolate Medium methodology recommended by the World Organisation for Animal Health. The duplex qPCR method brought new insights and unveiled cryptic infections as the co-occurrence of P. olseni and P. chesapeaki from in situ tissue samples in contrast to the RFTM diagnosis. The development of this duplex qPCR method is a fundamental work to monitor in situ co-infections that will lead to optimised resource management and conservation strategies to deal with emerging diseases.


Assuntos
Alveolados/isolamento & purificação , Bivalves/parasitologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Alveolados/genética , Animais , Especificidade da Espécie
8.
Mar Pollut Bull ; 167: 112341, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33865041

RESUMO

Ciliates comprise essential components of microzooplankton in diverse marine environments. However, the extent to which environmental variables shape the distribution of planktonic ciliates in complex estuarine systems remains unclear. Here, 52 samples were collected from the Pearl River Estuary, China to reveal the influence of environmental variables on planktonic ciliate communities. Distinct community compositions of ciliates were found in three identified water masses: Pearl River diluted water mass, South China Sea surface water mass, and South China Sea bottom water mass. Significant differences in abundance, biomass, cell size, and oral diameter structure of ciliates were also detected among the three water masses. The partial Mantel test showed that water mass (as represented by water temperature and salinity) surpassed other environmental variables to be the primary factor driving the dynamics of the ciliate community. This study revealed the controlling mechanisms of planktonic ciliate communities in a subtropical, hydrographically complex estuarine ecosystem.


Assuntos
Alveolados , Cilióforos , China , Ecossistema , Estuários , Plâncton , Rios , Água
9.
Mol Ecol ; 30(10): 2417-2433, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33756046

RESUMO

Parasites in aquatic systems are highly diverse and ubiquitous. In marine environments, parasite-host interactions contribute substantially to shaping microbial communities, but their nature and complexity remain poorly understood. In this study, we examined the relationship between Perkinsea parasitoids and bloom-forming dinoflagellate species. Our aim was to determine whether parasite-host species interactions are specific and whether the diversity and distribution of parasitoids are shaped by their dinoflagellate hosts. Several locations along the Catalan coast (NW Mediterranean Sea) were sampled during the blooms of five dinoflagellate species and the diversity of Perkinsea was determined by combining cultivation-based methods with metabarcoding of the V4 region of 18S rDNA. Most known species of Parviluciferaceae, and others not yet described, were detected, some of them coexisting in the same coastal location, and with a wide distribution. The specific parasite-host interactions determined for each of the studied blooms demonstrated the host preferences exhibited by parasitoids in nature. The dominance of a species within the parasitoid community is driven by the presence and abundances of its preferred host(s). The absence of parasitoid species, often associated with a low abundance of their preferred hosts, suggested that high infection rates are reached only under conditions that favour parasitoid propagation, especially dinoflagellate blooms.


Assuntos
Alveolados , Dinoflagelados , DNA Ribossômico , Dinoflagelados/genética , Interações Hospedeiro-Parasita , Mar Mediterrâneo
10.
Nat Microbiol ; 6(4): 425-434, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33495622

RESUMO

Apicomplexa are unicellular eukaryotes and obligate intracellular parasites, including Plasmodium (the causative agent of malaria) and Toxoplasma (one of the most widespread zoonotic pathogens). Rhoptries, one of their specialized secretory organelles, undergo regulated exocytosis during invasion1. Rhoptry proteins are injected directly into the host cell to support invasion and subversion of host immune function2. The mechanism by which they are discharged is unclear and appears distinct from those in bacteria, yeast, animals and plants. Here, we show that rhoptry secretion in Apicomplexa shares structural and genetic elements with the exocytic machinery of ciliates, their free-living relatives. Rhoptry exocytosis depends on intramembranous particles in the shape of a rosette embedded into the plasma membrane of the parasite apex. Formation of this rosette requires multiple non-discharge (Nd) proteins conserved and restricted to Ciliata, Dinoflagellata and Apicomplexa that together constitute the superphylum Alveolata. We identified Nd6 at the site of exocytosis in association with an apical vesicle. Sandwiched between the rosette and the tip of the rhoptry, this vesicle appears as a central element of the rhoptry secretion machine. Our results describe a conserved secretion system that was adapted to provide defence for free-living unicellular eukaryotes and host cell injection in intracellular parasites.


Assuntos
Alveolados/fisiologia , Organelas/metabolismo , Alveolados/classificação , Alveolados/ultraestrutura , Membrana Celular/metabolismo , Exocitose , Interações Hospedeiro-Parasita , Humanos , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Vesículas Secretórias/metabolismo
11.
Parasitol Int ; 80: 102186, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32916259

RESUMO

The parasitizing stage (trophozoite) of the protozoan parasite Perkinsus olseni progresses to the dormant stage (prezoosporangium) immediately after the death of the host through physiologically and morphologically drastic changes. This development is reproducible in Ray's fluid thioglycollate medium (RFTM). In this study, supplementation with tissue extract from a host, the Manila clam, significantly improved the efficiency of development, as determined by the numbers and sizes of developed prezoosporangia. Similar results were seen following supplementation with boiled host tissue extract, which indicates that a thermally stable component of the host is required for the parasite's development. Subsequently, we found that a commercially available lipid concentrate significantly increased prezoosporulation without host tissue, suggesting that the lipids in host tissue enhance prezoosporangia development. Moreover, we determined that yeast extract, sodium thioglycollate, and sodium chloride were the only components of RFTM required for prezoosporulation. Based on these findings, we prepared a simple, host-free medium for P. olseni prezoosporulation-Lipid concentrate Yeast extract Medium (LpcYM)-consisting of yeast extract, lipid concentrate, sodium thioglycollate, and sodium chloride. We confirmed that the prezoosporangia developed in LpcYM produce zoospores that are infectious to Manila clams and that trophozoites of other Perkinsus species (P. marinus, P. honshuensis, and P. chesapeaki) also develop to prezoosporangia in this host-free medium. As LpcYM has the simplest composition of prezoosporulation media available thus far, it enables us to conduct molecular and biochemical studies examining the drastic transformation process of this parasite.


Assuntos
Alveolados/crescimento & desenvolvimento , Bivalves/parasitologia , Meios de Cultura/análise , Cloreto de Sódio/química , Tioglicolatos/química , Trofozoítos/crescimento & desenvolvimento , Fermento Seco/química , Animais
12.
Parasitology ; 148(5): 532-538, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33353569

RESUMO

Since the discovery of Perkinsus marinus as the cause of dermo disease in Crassostrea virginica, salinity and temperature have been identified as the main environmental drivers of parasite prevalence. However, little is known about how these variables affect the movement of the parasite from host to water column. In order to elucidate how environmental factors can influence the abundance of this parasite in the water column, we conducted a series of experiments testing the effects of time of day, temperature and salinity on the release of P. marinus cells from infected oysters. We found that P. marinus cells were released on a diurnal cycle, with most cells released during the hottest and brightest period of the day (12:00-18:00). Temperature also had a strong and immediate effect on the number of cells released, but salinity did not, only influencing the intensity of infection over the course of several months. Taken together, our results demonstrate that (1) the number of parasites in the water column fluctuates according to a diurnal cycle, (2) temperature and salinity act on different timescales to influence parasite abundance, and (3) live infected oysters may substantially contribute to the abundance of transmissive parasites in the water column under particular environmental conditions.


Assuntos
Alveolados/fisiologia , Crassostrea/parasitologia , Interações Hospedeiro-Parasita , Animais , Ritmo Circadiano , Maryland , Salinidade , Temperatura
13.
Harmful Algae ; 100: 101944, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33298365

RESUMO

Perkinsea are a group of intracellular protist parasites that inhabit all types of aquatic environments and cause significant population declines of a wide variety of hosts. However, the diversity of this lineage is mostly represented by environmental rDNA sequences. Complete descriptions of Perkinsea that infect marine dinoflagellates have increased in recent literature due to the identification, isolation and culturing of representatives during bloom events, contributing to expand the knowledge on the diversity and ecology of the group. Shallow coastal areas in the Baltic Sea suffer seasonal dinoflagellate blooms. In summer 2016, two parasitoids were isolated during a Kryptoperidinium foliaceum bloom in the Baltic Sea. Morphological features and sequences of the small and large subunit of the ribosomal DNA gene revealed these two parasitoids were new species that belong to the genus Parvilucifera. This is the first time that Parvilucifera infections are reported in the Inner Baltic Sea. The first species, Parvilucifera sp. has some morphological and phylogenetic features in common with P. sinerae and P. corolla, although its ultrastructure could not be studied and the formal description could not be done. The second new species, named Parvilucifera catillosa, has several distinct morphological features in its zoospores (e.g. the presence of a rostrum), and in the shape and size of the apertures in the sporangium stage, which are larger and more protuberant than in the other species of the genus. Infections observed in the field and cross-infection experiments determined that the host range of both Parvilucifera species was restricted to dinoflagellates, each one showing a different host preference. The coexistence in the same environment by the two closely related parasitoids with very similar life cycles suggests that their niche separation is the preferred host.


Assuntos
Alveolados , Dinoflagelados , Animais , DNA Ribossômico/genética , Estágios do Ciclo de Vida , Filogenia
14.
Parasit Vectors ; 13(1): 599, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-33256809

RESUMO

BACKGROUND: Piroplasms are vector-borne intracellular hemoprotozoan parasites that infect wildlife and livestock. Wildlife species are reservoir hosts to a diversity of piroplasms and play an important role in the circulation, maintenance and evolution of these parasites. The potential for likely spillover of both pathogenic and non-pathogenic piroplasm parasites from wildlife to livestock is underlined when a common ecological niche is shared in the presence of a competent vector. METHOD: To investigate piroplasm diversity in wildlife and the cattle population of the greater Kafue ecosystem, we utilized PCR to amplify the 18S rRNA V4 hyper-variable region and meta-barcoding strategy using the Illumina MiSeq sequencing platform and amplicon sequence variant (ASV)-based bioinformatics pipeline to generate high-resolution data that discriminate sequences down to a single nucleotide difference. RESULTS: A parasite community of 45 ASVs corresponding to 23 species consisting of 4 genera of Babesia, Theileria, Hepatozoon and Colpodella, were identified in wildlife and the cattle population from the study area. Theileria species were detected in buffalo, impala, hartebeest, sable antelope, sitatunga, wild dog and cattle. In contrast, Babesia species were only observed in cattle and wild dog. Our results demonstrate possible spillover of these hemoprotozoan parasites from wildlife, especially buffalo, to the cattle population in the wildlife-livestock interface. CONCLUSION: We demonstrated that the deep amplicon sequencing of the 18S rRNA V4 hyper-variable region for wildlife was informative. Our results illustrated the diversity of piroplasma and the specificity of their hosts. They led us to speculate a possible ecological cycle including transmission from wildlife to domestic animals in the greater Kafue ecosystem. Thus, this approach may contribute to the establishment of appropriate disease control strategies in wildlife-livestock interface areas.


Assuntos
Alveolados/isolamento & purificação , Animais Selvagens/parasitologia , Infecções Protozoárias em Animais/parasitologia , Alveolados/classificação , Alveolados/genética , Animais , Animais Selvagens/classificação , Biodiversidade , Búfalos/parasitologia , Bovinos , Doenças dos Bovinos/parasitologia , Doenças do Cão/parasitologia , Cães , Filogenia , Infecções Protozoárias em Animais/epidemiologia , Zâmbia/epidemiologia
15.
PLoS One ; 15(12): e0243087, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33326418

RESUMO

Because more than 80% of species of gamete-spawning corals, including most Acroporidae species, do not inherit Symbiodiniaceae from their parents, they must acquire symbiont cells from sources in their environment. To determine whether photosynthetically competent Symbiodiniaceae expelled as fecal pellets from giant clams are capable of colonizing corals, we conducted laboratory experiments in which planula larvae of Acropora tenuis were inoculated with the cells in fecal pellets obtained from Tridacna crocea. T. crocea fecal pellets were administered once a day, and three days later, cells of Symbiodiniaceae from the fecal pellets had been taken up by the coral larvae. T. crocea fecal pellets were not supplied from the 4th day until the 8th day, and the cell densities in the larvae increased until the 8th day, which indicated the successful colonization by Symbiodiniaceae. The control group exhibited the highest mean percentage of larvae (100%) that were successfully colonized by culture strains of Symbiodiniaceae, and larvae inoculated with fecal pellets reached a colonization percentage of 66.7 ~ 96.7% on the 8th day. The highest colonization rate was achieved with the fecal pellets containing cells with high photosynthetic competency (Fv/Fm). Interestingly, the genetic composition of Symbiodiniaceae in the larvae retrieved on the 8th day differed from that in the fecal pellets and showed exclusive domination of the genus Symbiodinium. A minor but significant population of the genus Cladocopium in the fecal pellets was not inherited by the larvae. These experiments provided the first demonstration that the Symbiodiniaceae from tridacnine clams provided via fecal pellets can colonize and even proliferate in coral larvae.


Assuntos
Alveolados/isolamento & purificação , Antozoários/parasitologia , Bivalves/parasitologia , Alveolados/classificação , Alveolados/genética , Animais , Recifes de Corais , DNA de Protozoário/genética , Fezes/parasitologia , Fotossíntese , Análise de Sequência de DNA , Simbiose
16.
Zootaxa ; 4895(1): zootaxa.4895.1.1, 2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33311051

RESUMO

Species from almost all classes of ciliates are prone to be found inhabiting bromeliads in the Neotropics, from Mexico to Brazil, and the Antilles. Studies of ciliates recorded from bromeliads have been carried out from few bromeliad species, mainly in tropical forest. We compiled all available data of free living and sessile ciliates from bromeliads, including their geographic distribution and bromeliad identity. We provide a list of 170 ciliate species that have been recorded in 52 epiphytic and terrestrial bromeliad species, distributed in ten Neotropical countries . Most of the species belong to the Classes Oligohymenophorea, Colpodea and Spirotrichea. The largest number of ciliate species has been recorded in Brazil and Mexico. Bromeliothrix metopoides and Glaucomides bromelicola were the two species with the widest geographical distribution, 19 species have been recorded only in Mexico, 11 in the Antillean islands, and 89 only in Southamerica. Free living species prevailed over sessile species, and both represent 2% of the total ciliate species number. Sixteen ciliate species have been recorded only inhabiting in bromeliads. Although bromeliads show a high endemicity, their specificity is low in relation to ciliates.


Assuntos
Alveolados , Bromeliaceae , Cilióforos , Animais
17.
Clin Chem ; 66(11): 1381-1395, 2020 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-33141913

RESUMO

BACKGROUND: Metagenomic next generation sequencing (mNGS) is becoming increasingly available for pathogen detection directly from clinical specimens. These tests use target-independent, shotgun sequencing to detect potentially unlimited organisms. The promise of this methodology to aid infection diagnosis is demonstrated through early case reports and clinical studies. However, the optimal role of mNGS in clinical microbiology remains uncertain. CONTENT: We reviewed studies reporting clinical use of mNGS for pathogen detection from various specimen types, including cerebrospinal fluid, plasma, lower respiratory specimens, and others. Published clinical study data were critically evaluated and summarized to identify promising clinical indications for mNGS-based testing, to assess the clinical impact of mNGS for each indication, and to recognize test limitations. Based on these clinical studies, early testing recommendations are made to guide clinical utilization of mNGS for pathogen detection. Finally, current barriers to routine clinical laboratory implementation of mNGS tests are highlighted. SUMMARY: The promise of direct-from-specimen mNGS to enable challenging infection diagnoses has been demonstrated through early clinical studies of patients with meningitis or encephalitis, invasive fungal infections, community acquired pneumonia, and other clinical indications. However, the proportion of patient cases with positive clinical impact due to mNGS testing is low in published studies and the cost of testing is high, emphasizing the importance of improving our understanding of 'when to test' and for which patients mNGS testing is appropriate.


Assuntos
Líquidos Corporais/microbiologia , Líquidos Corporais/parasitologia , Sequenciamento de Nucleotídeos em Larga Escala/normas , Metagenômica/normas , Alveolados/genética , Bactérias/genética , Infecções Bacterianas/diagnóstico , Fungos/genética , Humanos , Micoses/diagnóstico , Infecções por Protozoários/diagnóstico
18.
PLoS One ; 15(10): e0228514, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33091033

RESUMO

Coral disease outbreaks are expected to increase in prevalence, frequency and severity due to climate change and other anthropogenic stressors. This is especially worrying for the Caribbean branching coral Acropora palmata which has already seen an 80% decrease in cover primarily due to disease. Despite the importance of this keystone species, there has yet to be a characterization of its transcriptomic response to disease exposure. In this study we provide the first transcriptomic analysis of 12 A. palmata genotypes and their symbiont Symbiodiniaceae exposed to disease in 2016 and 2017. Year was the primary driver of gene expression variance for A. palmata and the Symbiodiniaceae. We hypothesize that lower expression of ribosomal genes in the coral, and higher expression of transmembrane ion transport genes in the Symbiodiniaceae indicate that a compensation or dysbiosis may be occurring between host and symbiont. Disease response was the second driver of gene expression variance for A. palmata and included a core set of 422 genes that were significantly differentially expressed. Of these, 2 genes (a predicted cyclin-dependent kinase 11b and aspartate 1-decarboxylase) showed negative Log2 fold changes in corals showing transmission of disease, and positive Log2 fold changes in corals showing no transmission of disease, indicating that these may be important in disease resistance. Co-expression analysis identified two modules positively correlated to disease exposure, one enriched for lipid biosynthesis genes, and the other enriched in innate immune genes. The hub gene in the immune module was identified as D-amino acid oxidase, a gene implicated in phagocytosis and microbiome homeostasis. The role of D-amino acid oxidase in coral immunity has not been characterized but could be an important enzyme for responding to disease. Our results indicate that A. palmata mounts a core immune response to disease exposure despite differences in the disease type and virulence between 2016 and 2017. These identified genes may be important for future biomarker development in this Caribbean keystone species.


Assuntos
Alveolados/genética , Antozoários/parasitologia , Perfilação da Expressão Gênica/veterinária , Imunidade Inata , Animais , Antozoários/genética , Antozoários/imunologia , Mudança Climática , Regulação da Expressão Gênica , Genótipo , Proteínas de Protozoários/genética , Proteínas Ribossômicas/genética , Simbiose
19.
FEMS Microbiol Ecol ; 96(11)2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-32975560

RESUMO

The diversity of protists was researched in the Alboran Sea (SW Mediterranean Sea) by means of high-throughput sequencing technologies based on the amplification of the V9 region of 18S rRNA. Samples were collected at different depths in seven stations following an environmental gradient from a coastal upwelling zone to the core of an oligotrophic anticyclonic gyre (AG). Sampling was performed during summer, when the water column was stratified. The superphyla Alveolata, Stramenopila and Rhizaria accounted for 84% of the total operational taxonomic units (OTUs). The most diverse groups were Dinophyceae (21% of OTUs), Marine Alveolates-II (MALV-II; 20%), Ciliophora (9%) and MALV-I (6%). In terms of read abundance, the predominant groups were Dinophyceae (29%), Bacillariophyta (14%), MALV-II (11%) and Ciliophora (11%). Samples were clustered into three groups according to the sampling depth and position. The shallow community in coastal stations presented distinguishable patterns of diatoms and ciliates compared with AG stations. These results indicate that there was a strong horizontal coupling between phytoplankton and ciliate communities. Abundance of Radiolaria and Syndiniales increased with depth. Our analyses demonstrate that the stratification disruption produced by the AG caused shifts in the trophic ecology of the plankton assemblages inducing a transition from bottom-up to top-down control.


Assuntos
Alveolados , Rhizaria , Alveolados/genética , Biodiversidade , Mar Mediterrâneo , RNA Ribossômico 18S/genética , Rhizaria/genética
20.
Sci Rep ; 10(1): 14431, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32879396

RESUMO

Here, we analyzed patterns of taxon richness and endemism of freshwater protists in Europe. Even though the significance of physicochemical parameters but also of geographic constraints for protist distribution is documented, it remains unclear where regional areas of high protist diversity are located and whether areas of high taxon richness harbor a high proportion of endemics. Further, patterns may be universal for protists or deviate between taxonomic groups. Based on amplicon sequencing campaigns targeting the SSU and ITS region of the rDNA we address these patterns at two different levels of phylogenetic resolution. Our analyses demonstrate that protists have restricted geographical distribution areas. For many taxonomic groups the regions of high taxon richness deviate from those having a high proportion of putative endemics. In particular, the diversity of high mountain lakes as azonal habitats deviated from surrounding lowlands, i.e. many taxa were found exclusively in high mountain lakes and several putatively endemic taxa occurred in mountain regions like the Alps, the Pyrenees or the Massif Central. Beyond that, taxonomic groups showed a pronounced accumulation of putative endemics in distinct regions, e.g. Dinophyceae along the Baltic Sea coastline, and Chrysophyceae in Scandinavia. Many other groups did not have pronounced areas of increased endemism but geographically restricted taxa were found across Europe.


Assuntos
Biodiversidade , Água Doce/microbiologia , Alveolados/genética , Alveolados/fisiologia , Código de Barras de DNA Taxonômico , Água Doce/parasitologia , Fungos/genética , Fungos/fisiologia , Filogeografia , Estramenópilas/genética , Estramenópilas/fisiologia
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