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1.
Eur J Protistol ; 81: 125840, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34717075

RESUMO

Though representing a major component of eukaryotic biodiversity, many microbial eukaryotes remain poorly studied, including the focus of the present work, testate amoebae of the order Arcellinida (Amoebozoa) and non-model lineages of ciliates (Alveolata). In particular, knowledge of genome structures and changes in genome content over the often-complex life cycles of these lineages remains enigmatic. However, the limited available knowledge suggests that microbial eukaryotes have the potential to challenge our textbook views on eukaryotic genomes and genome evolution. In this study, we developed protocols for DAPI (4',6-diamidino-2-phenylindole) staining of Arcellinida nuclei and adapted protocols for ciliates. In addition, image analysis software was used to estimate the DNA content in the nuclei of Arcellinida and ciliates, and the measurements of target organisms were compared to those  of well-known model organisms.The results demonstrate that the methods we have developed for nuclear staining in these lineages are effective and can be applied to other microbial eukaryotic groups by adjusting certain stages in the protocols.


Assuntos
Cilióforos , Lobosea , Cilióforos/genética , DNA , Indóis , Filogenia , Coloração e Rotulagem
2.
Eur J Protistol ; 81: 125828, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34487957

RESUMO

Southern Spain is currently under threat of desertification as a consequence of global climate change, which pressures on fragile ecosystems such as caves. The organisms living in these extremely stable environments are particularly sensitive and prone to extinction, therefore they can be used as bioindicators for climate change. Cyanobacterial mats form peculiar and vulnerable micro-ecosystems at the entrance of caves and house a diversity of protists. Amongst them, Arcellinida testate amoebae have been traditionally used as bioindicators for environmental quality, notably because their narrow ecological tolerance and their key ecological position as top predators of the microbial foodwebs. We report here two new species of Arcellinida found in the cyanobacterial mats of cave Hundidero, in Sierra de Grazalema, Malaga province, whose traits suggest a narrow tolerance for changes in humidity. We provide a formal description for Difflugia alhadiqa sp. nov. and Heleopera baetica sp. nov. based on morphometrics and 18S rRNA gene data, and propose using the presence of these species to indicate the good health of the cyanobacterial mats, like miner's canaries for local climate.


Assuntos
Amoeba , Lobosea , Animais , Canários , Ecossistema , Espanha
3.
J Eukaryot Microbiol ; 68(5): e12857, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33987951

RESUMO

Vermamoeba vermiformis are one of the most prevalent free-living amoebae. These amoebae are ubiquitous and also thermotolerant. Of concern, V. vermiformis have been found in hospital water networks. Furthermore, associations between V. vermiformis and pathogenic bacteria have been reported, such as Legionella pneumophila. Moreover, V. vermiformis are well known to host viruses, bacteria, and other microorganisms and cases of keratitis due to V. vermiformis in conjunction with other amoebae have been reported. Despite the preceding, the medical importance of V. vermiformis is still an ongoing discussion and its genome has been only recently sequenced. Herein, we present a review of the current understanding of the biology and pathogenesis pertaining to V. vermiformis, as well as its' role as an etiological agent and trojan horse. An approach known as theranostics which combines both diagnosis and therapy could be utilized to eradicate and diagnose keratitis cases caused by such amoebae. Given the rise in global warming, it is imperative to investigate these rarely studied amoebae and to understand their importance in human health.


Assuntos
Amoeba , Lobosea , Bactérias , Água , Microbiologia da Água
4.
Eur J Protistol ; 79: 125788, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33887501

RESUMO

The reports of testate amoebae species in Colombia are limited to a few studies in lentic and peat bog systems; however, the diversity in lotic systems has been poorly investigated. Zooplankton sampling was performed in lotic environments of the Piedemonte Llanero in Colombia. Ten individuals of the species Arcella gandalfi were identified to document the first record of A. gandalfi from the Piedemonte Llanero in Colombia, expanding its distribution from Brazil to Colombia. This finding corroborates the status of A. gandalfi as a flagship species from the South America continent.


Assuntos
Distribuição Animal , Lobosea/classificação , Colômbia , Rios , Especificidade da Espécie
5.
Viruses ; 13(2)2021 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-33498382

RESUMO

Kaumoebavirus infects the amoeba Vermamoeba vermiformis and has recently been described as a distant relative of the African swine fever virus. To characterize the diversity and evolution of this novel viral genus, we report here on the isolation and genome sequencing of a second strain of Kaumoebavirus, namely LCC10. Detailed analysis of the sequencing data suggested that its 362-Kb genome is linear with covalently closed hairpin termini, so that DNA forms a single continuous polynucleotide chain. Comparative genomic analysis indicated that although the two sequenced Kaumoebavirus strains share extensive gene collinearity, 180 predicted genes were either gained or lost in only one genome. As already observed in another distant relative, i.e., Faustovirus, which infects the same host, the center and extremities of the Kaumoebavirus genome exhibited a higher rate of sequence divergence and the major capsid protein gene was colonized by type-I introns. A possible role of the Vermamoeba host in the genesis of these evolutionary traits is hypothesized. The Kaumoebavirus genome exhibited a significant gene strand bias over the two-third of genome length, a feature not seen in the other members of the "extended Asfarviridae" clade. We suggest that this gene strand bias was induced by a putative single origin of DNA replication located near the genome extremity that imparted a selective force favoring the genes positioned on the leading strand.


Assuntos
Asfarviridae/genética , Genoma Viral , Vírus Gigantes/genética , Vírus não Classificados/genética , Asfarviridae/classificação , Proteínas do Capsídeo/genética , Replicação do DNA , Vírus de DNA/classificação , Vírus de DNA/genética , Vírus de DNA/isolamento & purificação , DNA Viral/química , DNA Viral/genética , DNA Viral/metabolismo , Evolução Molecular , Genes Virais , Vírus Gigantes/classificação , Vírus Gigantes/isolamento & purificação , Vírus Gigantes/ultraestrutura , Lobosea/virologia , Filogenia , Esgotos/virologia , Proteínas Virais/genética , Vírus não Classificados/isolamento & purificação , Vírus não Classificados/ultraestrutura
6.
Eur J Protistol ; 77: 125759, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33348278

RESUMO

A new species of the "proteus-type" naked amoebae (large cells with discrete tubular pseudopodia) was isolated from tree bark sample of a birch tree in the surrounding of Kislovodsk town, Russia and named Polychaos centronucleolus n. sp. (Amoebozoa, Tubulinea). Amoebae of this species have a filamentous cell coat and a nucleus with a central compact nucleolus. This type of nucleolar organization has not been previously known for the genus Polychaos. A sequence of the 18S rRNA gene of this strain was obtained using whole genome amplification of DNA from the single amoeba cell, followed by NGS sequencing. The analysis of molecular data robustly groups this species with Polychaos annulatum within the family Hartmannellidae. Our results, together with the results of our previous studies, show that the taxonomic assignment of "proteus-type" amoebae species is becoming increasingly complex, and the taxonomic characters that can be used to classify these organisms are becoming more shadowed.


Assuntos
Nucléolo Celular/ultraestrutura , Lobosea/classificação , Betula/parasitologia , Lobosea/genética , Lobosea/ultraestrutura , Filogenia , Casca de Planta/parasitologia , RNA Ribossômico 18S/genética , Federação Russa , Especificidade da Espécie
7.
Microb Ecol ; 80(2): 366-383, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32385616

RESUMO

Salt contamination of lakes, due to the application of winter de-icing salts on roads, presents a significant environmental challenge in the "salt belt" region of eastern North America. The research reported here presents the first deployment of a previously published proxy tool based on Arcellinida (testate lobose amoebae) for monitoring road salt contamination. The research was conducted at Silver Lake in Eastern Ontario, a 4-km-long lake with the heavily traveled Trans-Canada Highway (HWY 7) transiting the entire southern shore. The lake showed elevated conductivity (297-310 µS/cm) and sub-brackish conditions (0.14-0.15 ppt). Sodium levels were also elevated near the roadside (median Na = 1020 ppm). Cluster analysis and nonmetric multidimensional scaling results revealed four distinct Arcellinida assemblages: "Stressed Cool Water Assemblage (SCWA)," "Deep Cold Water Assemblage (DCWA)," both from below the 8-m thermocline, and the shallower water "Shallow Water Assemblage 1 (SWA-1)" and "Shallow Water Assemblage 2 (SWA-2)". Redundancy analysis showed a minor response of Arcellinida to road salt contamination in shallower areas of the lake, with confounding variables significantly impacting assemblage distribution, particularly beneath the thermocline (e.g., water temperature, water depth, sediment runoff from catchment [Ti], sediment geochemistry [Ca, S]). The results of this study indicate that the trophic structure of the lake has to date only been modestly impacted by the cumulative nature of road salt contamination. Nonetheless, the Silver Lake results should be considered of concern and warrant continued arcellinidan biomonitoring to gauge the ongoing and long-term effects of road salt on its ecosystem.


Assuntos
Monitoramento Ambiental , Lagos/parasitologia , Lobosea/isolamento & purificação , Cloreto de Sódio/efeitos adversos , Poluentes Químicos da Água/efeitos adversos , Lagos/química , Lobosea/efeitos dos fármacos , Ontário , Salinidade , Estações do Ano
8.
J Eukaryot Microbiol ; 67(2): 154-166, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31560817

RESUMO

Cochliopodium is a lens-shaped genus of Amoebozoa characterized by a flexible layer of microscopic dorsal scales. Recent taxonomic and molecular studies reported cryptic diversity in this group and suggested that the often-used scale morphology is not a reliable character for species delineation in the genus. Here, we described three freshwater Cochliopodium spp. from the southeastern United States based on morphological, immunocytochemistry (ICC), and molecular data. A maximum-likelihood phylogenetic analysis and pairwise comparison of COI sequences of Cochliopodium species showed that each of these monoclonal cultures were genetically distinct from each other and any described species with molecular data. Two of the new isolates, "crystal UK-YT2" (Cochliopodium crystalli n. sp.) and "crystal-like UK-YT3" (C. jaguari n. sp.), formed a clade with C. larifeili, which all share a prominent microtubule organizing center (MTOC) and have cubical-shaped crystals. The "Marrs Spring UK-YT4" isolate, C. marrii n. sp., was 100% identical to "Cochliopodium sp. SG-2014 KJ569724." These sequences formed a clade with C. actinophorum and C. arabianum. While the new isolates can be separated morphologically, most of the taxonomic features used in the group show plasticity; therefore, Cochliopodium species can only be reliably identified with the help of molecular data.


Assuntos
Lobosea/classificação , Alabama , Complexo IV da Cadeia de Transporte de Elétrons/análise , Georgia , Imuno-Histoquímica , Lobosea/citologia , Lobosea/enzimologia , Microscopia , Proteínas de Protozoários/análise
9.
J Eukaryot Microbiol ; 67(2): 167-175, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31600008

RESUMO

Marine amebae of the genus Paramoeba (Amoebozoa, Dactylopodida) normally contain a eukaryotic endosymbiont known as Perkinsela-like organism (PLO). This is one of the characters to distinguish the genera Neoparamoeba and Paramoeba from other Dactylopodida. It is known that the PLO may be lost, but PLO-free strains of paramoebians were never available for molecular studies. Recently, we have described the first species of the genus Paramoeba which has no parasome-Paramoeba aparasomata. In this study, we present a mitochondrial genome of this species, compare it with that of Neoparamoeba pemaquidensis, and analyze the evolutionary dynamics of gene sequences and gene order rearrangements between these species. The mitochondrial genome of P. aparasomata is 46,254 bp long and contains a set of 31 protein-coding genes, 19 tRNAs, two rRNA genes, and 7 open reading frames. Our results suggest that these two mitochondrial genomes within the genus Paramoeba have rather similar organization and gene order, base composition, codon usage, the composition and structure of noncoding, and overlapping regions.


Assuntos
Genoma Mitocondrial , Genoma de Protozoário , Lobosea/genética , Estrutura Secundária de Proteína , Proteínas de Protozoários/química
10.
Microb Ecol ; 79(2): 443-458, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31432244

RESUMO

Arcellinida (testate lobose amoebae) are widely used as bio-indicators of lacustrine environmental change. Too much obscuring organic material in a gridded wet Petri dish preparation makes it difficult to observe all specimens present and slows quantification as the organic material has to be carefully worked through with a dissection probe. Chemical deflocculation using soda ash (Na2CO3·H2O), potassium hydroxide (KOH), or sodium hexametaphosphate ((NaPO3)6) has previously been shown to disaggregate and reduce organic content in lake sediments, but to date, no attempt has been made to comparatively evaluate the efficiency of these deflocculants in disaggregating organic content and their impact on Arcellinida analysis in lacustrine sediments. Here, we assess the effectiveness of soda ash, potassium hydroxide, and sodium hexametaphosphate treatments on removing organic content and the impact of those digestions on Arcellinida preservation in 126 sample aliquots subdivided from three sediment samples (YK-20, YK-25, and YK-57) collected from three lakes near Yellowknife, Northwest Territories, Canada. Following treatment, cluster analysis and Bray-Curtis dissimilarity matrix (BCDM) were utilized to determine whether treatments resulted in dissolution-driven changes in Arcellinida assemblage composition. Observed Arcellinida tests in aliquots increased drastically after treatment of organic-rich samples (47.5-452.7% in organic-rich aliquots and by 14.8% in aliquots with less organic matter). The BCDM results revealed that treatment with 5% KOH resulted in the highest reduction in observed organic content without significantly affecting Arcellinida assemblage structure, while soda ash and sodium hexametaphosphate treatments resulted in marginal organic matter reduction and caused severe damage to the arcellinidan tests.


Assuntos
Floculação , Sedimentos Geológicos/parasitologia , Lobosea/isolamento & purificação , Técnicas Microbiológicas/instrumentação , Lagos/parasitologia , Territórios do Noroeste , Parasitologia/métodos
11.
Virol J ; 16(1): 158, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842897

RESUMO

BACKGROUND: After the isolation of Acanthamoeba polyphaga mimivirus (APMV), the study and search for new giant viruses has been intensified. Most giant viruses are associated with free-living amoebae of the genus Acanthamoeba; however other giant viruses have been isolated in Vermamoeba vermiformis, such as Faustovirus, Kaumoebavirus and Orpheovirus. These studies have considerably expanded our knowledge about the diversity, structure, genomics, and evolution of giant viruses. Until now, there has been only one Orpheovirus isolate, and many aspects of its life cycle remain to be elucidated. METHODS: In this study, we performed an in-depth characterization of the replication cycle and particles of Orpheovirus by transmission and scanning electron microscopy, optical microscopy and IF assays. RESULTS: We observed, through optical and IF microscopy, morphological changes in V. vermiformis cells during Orpheovirus infection, as well as increased motility at 12 h post infection (h.p.i.). The viral factory formation and viral particle morphogenesis were analysed by transmission electron microscopy, revealing mitochondria and membrane recruitment into and around the electron-lucent viral factories. Membrane traffic inhibitor (Brefeldin A) negatively impacted particle morphogenesis. The first structure observed during particle morphogenesis was crescent-shaped bodies, which extend and are filled by the internal content until the formation of multi-layered mature particles. We also observed the formation of defective particles with different shapes and sizes. Virological assays revealed that viruses are released from the host by exocytosis at 12 h.p.i., which is associated with an increase of particle counts in the supernatant. CONCLUSIONS: The results presented here contribute to a better understanding of the biology, structures and important steps in the replication cycle of Orpheovirus.


Assuntos
Vírus de DNA/crescimento & desenvolvimento , Vírus Gigantes/crescimento & desenvolvimento , Replicação Viral , Antígenos Virais/análise , Vírus de DNA/ultraestrutura , Vírus Gigantes/ultraestrutura , Lobosea/virologia , Microscopia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Vírion/química , Vírion/ultraestrutura
12.
Parasitol Res ; 118(11): 3191-3194, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31511977

RESUMO

Aeromonas hydrophila, considered as an emerging pathogen, is increasingly involved in opportunistic human infections. This bacterium, mainly present in aquatic environments, can therefore develop relationships with the free-living amoeba Vermamoeba vermiformis in hospital water networks. We showed in this study that the joint presence of V. vermiformis and A. hydrophila led to an increased bacterial growth in the first 48 h of contact and moreover to the protection of the bacteria in adverse conditions even after 28 days. These results highlight the fact that strategies should be implemented to control the development of FLA in hospital water systems.


Assuntos
Aeromonas hydrophila/crescimento & desenvolvimento , Amoeba/microbiologia , Antibiose/fisiologia , Lobosea/microbiologia , Hospitais/estatística & dados numéricos , Humanos , Água/análise , Microbiologia da Água
13.
Curr Biol ; 29(6): 991-1001.e3, 2019 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-30827918

RESUMO

Life was microbial for the majority of Earth's history, but as very few microbial lineages leave a fossil record, the Precambrian evolution of life remains shrouded in mystery. Shelled (testate) amoebae stand out as an exception with rich documented diversity in the Neoproterozoic as vase-shaped microfossils (VSMs). While there is general consensus that most of these can be attributed to the Arcellinida lineage in Amoebozoa, it is still unclear whether they can be used as key fossils for interpretation of early eukaryotic evolution. Here, we present a well-resolved phylogenomic reconstruction based on 250 genes, obtained using single-cell transcriptomic techniques from a representative selection of 19 Arcellinid testate amoeba taxa. The robust phylogenetic framework enables deeper interpretations of evolution in this lineage and demanded an updated classification of the group. Additionally, we performed reconstruction of ancestral morphologies, yielding hypothetical ancestors remarkably similar to existing Neoproterozoic VSMs. We demonstrate that major lineages of testate amoebae were already diversified before the Sturtian glaciation (720 mya), supporting the hypothesis that massive eukaryotic diversification took place in the early Neoproterozoic and congruent with the interpretation that VSM are arcellinid testate amoebae.


Assuntos
Fósseis/anatomia & histologia , Lobosea/classificação , Lobosea/genética , Genes de Protozoários , Filogenia
14.
Microb Ecol ; 78(2): 534-538, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30535652

RESUMO

Unicellular free-living microbial eukaryotes of the order Arcellinida (Tubulinea; Amoebozoa) and Euglyphida (Cercozoa; SAR), commonly termed testate amoebae, colonise almost every freshwater ecosystem on Earth. Patterns in the distribution and productivity of these organisms are strongly linked to abiotic conditions-particularly moisture availability and temperature-however, the ecological impacts of changes in salinity remain poorly documented. Here, we examine how variable salt concentrations affect a natural community of Arcellinida and Euglyphida on a freshwater sub-Antarctic peatland. We principally report that deposition of wind-blown oceanic salt-spray aerosols onto the peatland surface corresponds to a strong reduction in biomass and to an alteration in the taxonomic composition of communities in favour of generalist taxa. Our results suggest novel applications of this response as a sensitive tool to monitor salinisation of coastal soils and to detect salinity changes within peatland palaeoclimate archives. Specifically, we suggest that these relationships could be used to reconstruct millennial scale variability in salt-spray deposition-a proxy for changes in wind-conditions-from sub-fossil communities of Arcellinida and Euglyphida preserved in exposed coastal peatlands.


Assuntos
Cercozoários/crescimento & desenvolvimento , Lobosea/crescimento & desenvolvimento , Regiões Antárticas , Biodiversidade , Cercozoários/metabolismo , Ecossistema , Lobosea/metabolismo , Salinidade , Cloreto de Sódio/análise , Cloreto de Sódio/metabolismo , Solo/química , Solo/parasitologia
15.
Microb Ecol ; 77(4): 1014-1024, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30470844

RESUMO

Studies on testate amoeba species distribution at small scales (i.e., single peatland sites) are rare and mostly focus on bogs or mineral-poor Sphagnum fens, leaving spatial patterns within mineral-rich fens completely unexplored. In this study, two mineral-rich fen sites of contrasting groundwater chemistry and moss layer composition were selected for the analysis of testate amoeba compositional variance within a single site. At each study site, samples from 20 randomly chosen moss-dominated plots were collected with several environmental variables being measured at each sampling spot. We also distinguished between empty shells and living individuals to evaluate the effect of empty shell inclusion on recorded species distribution. At the heterogeneous-rich Sphagnum-fen, a clear composition turnover in testate amoebae between Sphagnum-dominated and brown moss-dominated samples was closely related to water pH, temperature and redox potential. We also found notable species composition variance within the homogeneous calcareous fen, yet it was not as high as for the former site and the likely drivers of community assembly remained unidentified. The exclusion of empty shells provided more accurate data on species distribution as well as their relationship with some environmental variables, particularly moisture. Small-scale variability in species composition of communities seems to be a worthwhile aspect in testate amoeba research and should be considered in future sampling strategies along with a possible empty shell bias for more precise understanding of testate amoeba ecology and paleoecology.


Assuntos
Lobosea/fisiologia , Microbiota , Solo/química , Briófitas/crescimento & desenvolvimento , República Tcheca , Lobosea/classificação , Áreas Alagadas
16.
J Eukaryot Microbiol ; 66(1): 120-139, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29791056

RESUMO

We report the discovery of a new genus of heterolobosean flagellates, Dactylomonas gen. nov., with two species, D. venusta sp. nov. and D. crassa sp. nov. Phylogenetic analysis of the SSU rRNA gene showed that Dactylomonas is closely related to the amoeba Selenaion, the deepest-branching lineage of Tetramitia. Dactylomonads possess two flagella, and ultrastructural studies revealed an unexpected organization of the flagellar apparatus, which resembled Pharyngomonada (the second lineage of Heterolobosea) instead of Tetramitia: basal bodies were orthogonal to each other and a putative root R1 was present in the mastigont. On the other hand, Dactylomonas displayed several features uncommon in Heterolobosea: a microtubular corset, a distinctive rostrum supported by the main part of the right microtubular root, a finger-like projection on the proximal part of the recurrent flagellum, and absence of a ventral groove. In addition, Dactylomonas is anaerobic and seems to have lost mitochondrial cristae. Dactylomonas and Selenaion are accommodated in the family Selenaionidae fam. nov. and order Selenionida ord. nov. The taxonomy of Tetramitia is partially revised, and the family Neovahlkampfiidae fam. nov. is established.


Assuntos
Classificação , Lobosea/classificação , RNA de Protozoário/análise , Lobosea/citologia , Lobosea/genética , Lobosea/ultraestrutura , Filogenia
17.
Eur J Protistol ; 66: 156-165, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30366198

RESUMO

Molecular data have considerably contributed to building the taxonomy of protists. Recently, the systematics of Hyalospheniidae (Amoebozoa; Tubulinea; Arcellinida) has been widely revised, with implications extending to ecological, biogeographical and evolutionary investigations. Certain taxa, however, still have an uncertain phylogenetic position, including the common and conspicuous species Nebela militaris. A phylogenetic reconstruction of the Hyalospheniidae using partial sequences of the mitochondrial Cytochrome Oxidase Subunit 1 (COI) gene shows that N. militaris does not belong to genus Nebela, but should be placed in its own genus. The morphological singularities (strongly curved pseudostome and a marked notch in lateral view) and phylogenetic placement of our isolates motivated the creation of a new genus: Alabasta gen. nov. Based on their morphology, we include in this genus Nebela kivuense and Nebela longicollis. We discuss the position of genus Alabasta within Hyalospheniidae, and the species that could integrate this new genus based on their morphological characteristics.


Assuntos
Lobosea/classificação , Filogenia , DNA de Protozoário/genética , DNA Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Lobosea/genética , Especificidade da Espécie
18.
Protist ; 169(2): 190-205, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29614434

RESUMO

Morphological features are often the only characteristics suitable for identification of taxa in testate amoebae, especially in ecological and palaeoecological studies. However, whereas the morphology of some species is rather stable it may vary considerably in others. Within the order Arcellinida the genus Trigonopyxis with the type species Trigonopyxis arcula is morphologically highly variable. To identify reliable characteristics for morphology-based taxon delineation we investigated variations in shell size, pseudostome diameter and pseudostome form in T. arcula from three different sites of the Ecuadorian Andes, where these characteristics vary even more than previously described. Further, we investigated if morphological characteristics in Trigonopyxis varied with changes in environmental factors. We studied 951 shells of Trigonopyxis collected along an altitudinal gradient with varying abiotic factors. We established a method for characterization of the pseudostome form, which lead to five different morphotypes. Our results suggest that shell size alone is not an appropriate character for taxon delineation but can be used as an indicator for changes in environmental conditions. In contrast, the pseudostome form might be used for taxon delineation, but likely also varies considerably within taxa. Overall, the study provides an overview of the morphological variability of the genus Trigonopyxis.


Assuntos
Amebozoários/genética , Amoeba/classificação , Amoeba/genética , Amebozoários/classificação , DNA de Protozoário/genética , DNA Ribossômico/genética , Lobosea/classificação , Lobosea/genética , Filogenia
19.
J Eukaryot Microbiol ; 65(5): 661-668, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29443446

RESUMO

Diverse species of Legionella and Legionella-like amoebal pathogens (LLAPs) have been identified as intracellular bacteria in many amoeboid protists. There are, however, other amoeboid groups such as testate amoeba for which we know little about their potential to host such bacteria. In this study, we assessed the occurrence and diversity of Legionella spp. in cultures and environmental isolates of freshwater arcellinid testate amoebae species, Arcella hemispherica, Arcella intermedia, and Arcella vulgaris, via 16S rRNA gene sequence analyses and fluorescent in situ hybridization (FISH). Analysis of the 16S rRNA gene sequences indicated that A. hemispherica, A. intermedia, and A. vulgaris host Legionella-like bacteria with 94-98% identity to other Legionella spp. based on NCBI BLAST search. Phylogenetic analysis placed Legionella-like Arcella-associated bacteria (LLAB) in three different clusters within a tree containing all other members of Legionella and LLAPs. The intracellular localization of the Legionella within Arcella hosts was confirmed using FISH with a Legionella-specific probe. This study demonstrates that the host range of Legionella and Legionella-like bacteria in the Amoebozoa extends beyond members of "naked" amoebae species, with members of the testate amoebae potentially serving an ecological role in the dispersal, protection, and replication of Legionella spp. in natural environments.


Assuntos
Bactérias/isolamento & purificação , Lobosea/microbiologia , Bactérias/classificação , Bactérias/genética , Biodiversidade , DNA Bacteriano/genética , DNA Ribossômico/genética , Água Doce/microbiologia , Água Doce/parasitologia , Legionella/classificação , Legionella/genética , Legionella/isolamento & purificação , Lobosea/classificação , Filogenia , RNA Ribossômico 16S/genética
20.
Appl Environ Microbiol ; 84(6)2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29305503

RESUMO

Fecal indicator bacteria (FIB) are the basis for water quality regulations and are considered proxies for waterborne pathogens when conducting human health risk assessments. The direct detection of pathogens in water and simultaneous identification of the source of fecal contamination are possible with microarrays, circumventing the drawbacks to FIB approaches. A multigene target microarray was used to assess the prevalence of waterborne pathogens in a fecally impaired mixed-use watershed. The results indicate that fecal coliforms have improved substantially in the watershed since its listing as a 303(d) impaired stream in 2002 and are now near United States recreational water criterion standards. However, waterborne pathogens are still prevalent in the watershed, as viruses (bocavirus, hepatitis E and A viruses, norovirus, and enterovirus G), bacteria (Campylobacter spp., Clostridium spp., enterohemorrhagic and enterotoxigenic Escherichia coli, uropathogenic E. coli, Enterococcus faecalis, Helicobacter spp., Salmonella spp., and Vibrio spp.), and eukaryotes (Acanthamoeba spp., Entamoeba histolytica, and Naegleria fowleri) were detected. A comparison of the stream microbial ecology with that of sewage, cattle, and swine fecal samples revealed that human sources of fecal contamination dominate in the watershed. The methodology presented is applicable to a wide range of impaired streams for the identification of human health risk due to waterborne pathogens and for the identification of areas for remediation efforts.IMPORTANCE The direct detection of waterborne pathogens in water overcomes many of the limitations of the fecal indicator paradigm. Furthermore, the identification of the source of fecal impairment aids in identifying areas for remediation efforts. Multitarget gene microarrays are shown to simultaneously identify waterborne pathogens and aid in determining the sources of impairment, enabling further focused investigations. This study shows the use of this methodology in a historically impaired watershed in which total maximum daily load reductions have been successfully implemented to reduce risk. The results suggest that while the fecal indicators have been reduced more than 96% and are nearing recreational water criterion levels, pathogens are still detectable in the watershed. Microbial source tracking results show that additional remediation efforts are needed to reduce the impact of human sewage in the watershed.


Assuntos
Bactérias/isolamento & purificação , Monitoramento Ambiental/métodos , Lobosea/isolamento & purificação , Rios/microbiologia , Rios/parasitologia , Esgotos/análise , Vírus/isolamento & purificação , Bactérias/genética , Conservação dos Recursos Hídricos , Fezes/microbiologia , Fezes/parasitologia , Fezes/virologia , Lobosea/genética , Rios/virologia , Vírus/genética , West Virginia
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