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1.
Harmful Algae ; 68: 1-16, 2017 09.
Artículo en Inglés | MEDLINE | ID: mdl-28962972

RESUMEN

This study investigated the genetic diversity of phytoplankton communities in six shallow lagoons located on the French coast of the northwestern Mediterranean Sea that represented a trophic gradient ranging from oligotrophic to hypereutrophic. The phytoplankton communities were sampled once a month from spring (May) to the beginning of autumn (September/early October) in 2012 and fractionated by size. Metabarcodes were generated from cDNAs by targeting the D1-D2 region of the 28S rRNA gene and pyrosequenced using Roche 454 technology. Examination of the annotated barcodes revealed harmful algal species not previously documented in these lagoons. Three ichthyotoxic species belonging to Pfiesteriaceae were detected: Luciella masanensis was relatively widespread and abundant in many samples, whereas Pfiesteria piscicida and Stoeckeria changwonensis were found as single barcode sequences. Furthermore, a phylogenetic analysis of barcodes annotated as belonging to Pfiesteriaceae suggested the existence of two previously undescribed clades. The other toxic or potentially harmful dinoflagellates detected through rare barcodes were Dinophysis acuminata, Vulcanodinium rugosum, Alexandrium andersonii and A. ostenfeldii. The two most abundant dinoflagellate taxa were Gymnodinium litoralis and Akashiwo sanguinea with respect to sequence numbers. Four diatom species from the genus Pseudo-nitzschia that potentially produce domoic acid were identified (P. galaxiae, P. delicatissima, P. brasiliana and P. calliantha). These observations are discussed in terms of the literature and monitoring records related to the identified taxa in this Mediterranean area.


Asunto(s)
Código de Barras del ADN Taxonómico/métodos , Ecosistema , Genes de ARNr , Floraciones de Algas Nocivas , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , ARN Ribosómico 28S/genética , Biomasa , Dinoflagelados/clasificación , Dinoflagelados/genética , Geografía , Mar Mediterráneo , Filogenia , Fitoplancton/clasificación , Fitoplancton/genética
2.
J Eukaryot Microbiol ; 64(3): 407-411, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-28337822

RESUMEN

Universal taxonomic frameworks have been critical tools to structure the fields of botany, zoology, mycology, and bacteriology as well as their large research communities. Animals, plants, and fungi have relatively solid, stable morpho-taxonomies built over the last three centuries, while bacteria have been classified for the last three decades under a coherent molecular taxonomic framework. By contrast, no such common language exists for microbial eukaryotes, even though environmental '-omics' surveys suggest that protists make up most of the organismal and genetic complexity of our planet's ecosystems! With the current deluge of eukaryotic meta-omics data, we urgently need to build up a universal eukaryotic taxonomy bridging the protist -omics age to the fragile, centuries-old body of classical knowledge that has effectively linked protist taxa to morphological, physiological, and ecological information. UniEuk is an open, inclusive, community-based and expert-driven international initiative to build a flexible, adaptive universal taxonomic framework for eukaryotes. It unites three complementary modules, EukRef, EukBank, and EukMap, which use phylogenetic markers, environmental metabarcoding surveys, and expert knowledge to inform the taxonomic framework. The UniEuk taxonomy is directly implemented in the European Nucleotide Archive at EMBL-EBI, ensuring its broad use and long-term preservation as a reference taxonomy for eukaryotes.


Asunto(s)
Clasificación , Eucariontes/clasificación , Animales , Bacterias/clasificación , Biodiversidad , Bases de Datos de Ácidos Nucleicos , Ecosistema , Ambiente , Eucariontes/citología , Eucariontes/genética , Eucariontes/fisiología , Células Eucariotas , Hongos/clasificación , Filogenia
3.
ISME J ; 11(6): 1331-1344, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28338675

RESUMEN

Collodaria are heterotrophic marine protists that exist either as large colonies composed of hundreds of cells or as large solitary cells. All described species so far harbour intracellular microalgae as photosymbionts. Although recent environmental diversity surveys based on molecular methods demonstrated their consistently high contribution to planktonic communities and their worldwide occurrence, our understanding of their diversity and biogeography is still very limited. Here we estimated the 18S ribosomal DNA (rDNA) gene copies per collodarian cell for solitary (5770±1960 small subunit (SSU) rDNA copies) and colonial specimens (37 474±17 799 SSU rDNA copies, for each individual cell within a colony) using single-specimen quantitative PCR. We then investigated the environmental diversity of Collodaria within the photic zone through the metabarcoding survey from the Tara Oceans expedition and found that the two collodarian families Collosphaeridae and Sphaerozoidae contributed the most to the collodarian diversity and encompassed mostly cosmopolitan taxa. Although the biogeographical patterns were homogeneous within each biogeochemical biome considered, we observed that coastal biomes were consistently less diverse than oceanic biomes and were dominated by the Sphaerozoidae while the Collosphaeridae were dominant in the open oceans. The significant relationships with six environmental variables suggest that collodarian diversity is influenced by the trophic status of oceanic provinces and increased towards more oligotrophic regions.


Asunto(s)
Océanos y Mares , Filogenia , Rhizaria/genética , Rhizaria/fisiología , Distribución Animal , Animales , ADN Ribosómico/genética , Variación Genética , Plancton , ARN Ribosómico 18S/genética
4.
Curr Biol ; 26(22): 3060-3065, 2016 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-27875689

RESUMEN

The world's oceans represent by far the largest biome, with great importance for the global ecosystem [1-4]. The vast majority of ocean biomass and biodiversity is composed of microscopic plankton. Recent results from the Tara Oceans metabarcoding study revealed that a significant part of the plankton in the upper sunlit layer of the ocean is represented by an understudied group of heterotrophic excavate flagellates called diplonemids [5, 6]. We have analyzed the diversity and distribution patterns of diplonemid populations on the extended set of Tara Oceans V9 18S rDNA metabarcodes amplified from 850 size- fractionated plankton communities sampled across 123 globally distributed locations, for the first time also including samples from the mesopelagic zone, which spans the depth from about 200 to 1,000 meters. Diplonemids separate into four major clades, with the vast majority falling into the deep-sea pelagic diplonemid clade. Remarkably, diversity of this clade inferred from metabarcoding data surpasses even that of dinoflagellates, metazoans, and rhizarians, qualifying diplonemids as possibly the most diverse group of marine planktonic eukaryotes. Diplonemids display strong vertical separation between the photic and mesopelagic layers, with the majority of their relative abundance and diversity occurring in deeper waters. Globally, diplonemids display no apparent biogeographic structuring, with a few hyperabundant cosmopolitan operational taxonomic units (OTUs) dominating their communities. Our results suggest that the planktonic diplonemids are among the key heterotrophic players in the largest ecosystem of our biosphere, yet their roles in this ecosystem remain unknown.


Asunto(s)
Biodiversidad , Ecosistema , Euglenozoos/clasificación , Plancton/clasificación , Organismos Acuáticos/fisiología , Código de Barras del ADN Taxonómico , Euglenozoos/genética , Océanos y Mares , Plancton/genética , ARN Protozoario/genética , ARN Ribosómico 18S/genética , Análisis de Secuencia de ARN
5.
Sci Rep ; 6: 33555, 2016 09 16.
Artículo en Inglés | MEDLINE | ID: mdl-27633177

RESUMEN

Illumina reads of the SSU-rDNA-V9 region obtained from the circumglobal Tara Oceans expedition allow the investigation of protistan plankton diversity patterns on a global scale. We analyzed 6,137,350 V9-amplicons from ocean surface waters and the deep chlorophyll maximum, which were taxonomically assigned to the phylum Ciliophora. For open ocean samples global planktonic ciliate diversity is relatively low (ca. 1,300 observed and predicted ciliate OTUs). We found that 17% of all detected ciliate OTUs occurred in all oceanic regions under study. On average, local ciliate OTU richness represented 27% of the global ciliate OTU richness, indicating that a large proportion of ciliates is widely distributed. Yet, more than half of these OTUs shared <90% sequence similarity with reference sequences of described ciliates. While alpha-diversity measures (richness and exp(Shannon H)) are hardly affected by contemporary environmental conditions, species (OTU) turnover and community similarity (ß-diversity) across taxonomic groups showed strong correlation to environmental parameters. Logistic regression models predicted significant correlations between the occurrence of specific ciliate genera and individual nutrients, the oceanic carbonate system and temperature. Planktonic ciliates displayed distinct vertical distributions relative to chlorophyll a. In contrast, the Tara Oceans dataset did not reveal any evidence that latitude is structuring ciliate communities.


Asunto(s)
Organismos Acuáticos/fisiología , Biodiversidad , Internacionalidad , Océanos y Mares , Plancton/fisiología , Organismos Acuáticos/clasificación , Organismos Acuáticos/genética , Clorofila/metabolismo , Variación Genética , Geografía , Plancton/clasificación , Plancton/genética , Estadísticas no Paramétricas
6.
FEMS Microbiol Ecol ; 92(8)2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-27267932

RESUMEN

Marine protist diversity inventories have largely focused on planktonic environments, while benthic protists have received relatively little attention. We therefore hypothesize that current diversity surveys have only skimmed the surface of protist diversity in marine sediments, which may harbor greater diversity than planktonic environments. We tested this by analyzing sequences of the hypervariable V4 18S rRNA from benthic and planktonic protist communities sampled in European coastal regions. Despite a similar number of OTUs in both realms, richness estimations indicated that we recovered at least 70% of the diversity in planktonic protist communities, but only 33% in benthic communities. There was also little overlap of OTUs between planktonic and benthic communities, as well as between separate benthic communities. We argue that these patterns reflect the heterogeneity and diversity of benthic habitats. A comparison of all OTUs against the Protist Ribosomal Reference database showed that a higher proportion of benthic than planktonic protist diversity is missing from public databases; similar results were obtained by comparing all OTUs against environmental references from NCBI's Short Read Archive. We suggest that the benthic realm may therefore be the world's largest reservoir of marine protist diversity, with most taxa at present undescribed.


Asunto(s)
Organismos Acuáticos/clasificación , Organismos Acuáticos/aislamiento & purificación , Sedimentos Geológicos/microbiología , Sedimentos Geológicos/parasitología , Respiraderos Hidrotermales/microbiología , Respiraderos Hidrotermales/parasitología , Plancton/clasificación , Plancton/aislamiento & purificación , Secuencia de Bases , Biodiversidad , ADN/genética , Diatomeas/clasificación , Diatomeas/aislamiento & purificación , Ecosistema , Foraminíferos/clasificación , Foraminíferos/aislamiento & purificación , Filogenia , Plancton/genética , ARN Ribosómico 18S/genética , Análisis de Secuencia de ADN
7.
ISME J ; 10(10): 2419-34, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27003244

RESUMEN

Bolidomonas is a genus of picoplanktonic flagellated algae that is closely related to diatoms. Triparma laevis, a species belonging to the Parmales, which are small cells with a siliceous covering, has been shown to form a monophyletic group with Bolidomonas. We isolated several novel strains of Bolidophyceae that have permitted further exploration of the diversity of this group using nuclear, plastidial and mitochondrial genes. The resulting phylogenetic data led us to formally emend the taxonomy of this group to include the Parmales within the Bolidophyceae, to combine Bolidomonas within Triparma and to define a novel species, Triparma eleuthera sp. nov. The global distribution of Bolidophyceae was then assessed using environmental sequences available in public databases, as well as a large 18S rRNA V9 metabarcode data set from the Tara Oceans expedition. Bolidophyceans appear ubiquitous throughout the sampled oceans but always constitute a minor component of the phytoplankton community, corresponding to at most ~4% of the metabarcodes from photosynthetic groups (excluding dinoflagellates). They are ~10 times more abundant in the small size fraction (0.8-5 µm) than in larger size fractions. T. eleuthera sp. nov. constitutes the most abundant and most widespread operational taxonomic unit (OTU) followed by T. pacifica, T. mediterranea and the T. laevis clade. The T. mediterranea OTU is characteristic of Mediterranean Sea surface waters and the T. laevis clade OTU is most prevalent in colder waters, in particular off Antarctica.


Asunto(s)
Biodiversidad , Diatomeas/aislamiento & purificación , Fitoplancton/aislamiento & purificación , Agua de Mar/parasitología , Regiones Antárticas , ADN Ribosómico/genética , Diatomeas/clasificación , Diatomeas/genética , Mar Mediterráneo , Datos de Secuencia Molecular , Océanos y Mares , Filogenia , Fitoplancton/clasificación , Fitoplancton/genética
8.
Proc Natl Acad Sci U S A ; 113(11): E1516-25, 2016 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-26929361

RESUMEN

Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered.


Asunto(s)
Biodiversidad , Diatomeas/genética , Océanos y Mares , Organismos Acuáticos , ADN Ribosómico , Bases de Datos Factuales , Diatomeas/clasificación , Ecosistema , Microscopía/métodos , Fitoplancton , Reproducibilidad de los Resultados
9.
Nat Commun ; 7: 10543, 2016 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-26842659

RESUMEN

Biomineralization by marine phytoplankton, such as the silicifying diatoms and calcifying coccolithophores, plays an important role in carbon and nutrient cycling in the oceans. Silicification and calcification are distinct cellular processes with no known common mechanisms. It is thought that coccolithophores are able to outcompete diatoms in Si-depleted waters, which can contribute to the formation of coccolithophore blooms. Here we show that an expanded family of diatom-like silicon transporters (SITs) are present in both silicifying and calcifying haptophyte phytoplankton, including some globally important coccolithophores. Si is required for calcification in these coccolithophores, indicating that Si uptake contributes to the very different forms of biomineralization in diatoms and coccolithophores. Significantly, SITs and the requirement for Si are absent from highly abundant bloom-forming coccolithophores, such as Emiliania huxleyi. These very different requirements for Si in coccolithophores are likely to have major influence on their competitive interactions with diatoms and other siliceous phytoplankton.


Asunto(s)
Calcificación Fisiológica , Diatomeas/metabolismo , Haptophyta/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Silicio/metabolismo , Electroforesis en Gel de Poliacrilamida , Perfilación de la Expresión Génica , Haptophyta/genética , Haptophyta/ultraestructura , Proteínas de Transporte de Membrana/genética , Microscopía Electrónica , Microscopía Fluorescente , Fitoplancton , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Agua de Mar/química
10.
Nature ; 532(7600): 465-470, 2016 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-26863193

RESUMEN

The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterized. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria and alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of a few bacterial and viral genes can predict a significant fraction of the variability in carbon export in these regions.


Asunto(s)
Organismos Acuáticos/metabolismo , Carbono/metabolismo , Ecosistema , Plancton/metabolismo , Agua de Mar/química , Organismos Acuáticos/genética , Organismos Acuáticos/aislamiento & purificación , Clorofila/metabolismo , Dinoflagelados/genética , Dinoflagelados/aislamiento & purificación , Dinoflagelados/metabolismo , Expediciones , Genes Bacterianos , Genes Virales , Geografía , Océanos y Mares , Fotosíntesis , Plancton/genética , Plancton/aislamiento & purificación , Agua de Mar/microbiología , Agua de Mar/parasitología , Synechococcus/genética , Synechococcus/aislamiento & purificación , Synechococcus/metabolismo , Synechococcus/virología
11.
ISME J ; 10(3): 693-706, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26405830

RESUMEN

A marine symbiosis has been recently discovered between prymnesiophyte species and the unicellular diazotrophic cyanobacterium UCYN-A. At least two different UCYN-A phylotypes exist, the clade UCYN-A1 in symbiosis with an uncultured small prymnesiophyte and the clade UCYN-A2 in symbiosis with the larger Braarudosphaera bigelowii. We targeted the prymnesiophyte-UCYN-A1 symbiosis by double CARD-FISH (catalyzed reporter deposition-fluorescence in situ hybridization) and analyzed its abundance in surface samples from the MALASPINA circumnavigation expedition. Our use of a specific probe for the prymnesiophyte partner allowed us to verify that this algal species virtually always carried the UCYN-A symbiont, indicating that the association was also obligate for the host. The prymnesiophyte-UCYN-A1 symbiosis was detected in all ocean basins, displaying a patchy distribution with abundances (up to 500 cells ml(-1)) that could vary orders of magnitude. Additional vertical profiles taken at the NE Atlantic showed that this symbiosis occupied the upper water column and disappeared towards the Deep Chlorophyll Maximum, where the biomass of the prymnesiophyte assemblage peaked. Moreover, sequences of both prymnesiophyte partners were searched within a large 18S rDNA metabarcoding data set from the Tara-Oceans expedition around the world. This sequence-based analysis supported the patchy distribution of the UCYN-A1 host observed by CARD-FISH and highlighted an unexpected homogeneous distribution (at low relative abundance) of B. bigelowii in the open ocean. Our results demonstrate that partners are always in symbiosis in nature and show contrasted ecological patterns of the two related lineages.


Asunto(s)
Cianobacterias/fisiología , Haptophyta/microbiología , Simbiosis , Cianobacterias/clasificación , Cianobacterias/genética , Cianobacterias/aislamiento & purificación , Haptophyta/fisiología , Hibridación Fluorescente in Situ , Fijación del Nitrógeno , Océanos y Mares , Filogenia , Agua de Mar/microbiología
12.
ISME J ; 10(6): 1424-36, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-26684730

RESUMEN

Symbiotic partnerships between heterotrophic hosts and intracellular microalgae are common in tropical and subtropical oligotrophic waters of benthic and pelagic marine habitats. The iconic example is the photosynthetic dinoflagellate genus Symbiodinium that establishes mutualistic symbioses with a wide diversity of benthic hosts, sustaining highly biodiverse reef ecosystems worldwide. Paradoxically, although various species of photosynthetic dinoflagellates are prevalent eukaryotic symbionts in pelagic waters, Symbiodinium has not yet been reported in symbiosis within oceanic plankton, despite its high propensity for the symbiotic lifestyle. Here we report a new pelagic photosymbiosis between a calcifying ciliate host and the microalga Symbiodinium in surface ocean waters. Confocal and scanning electron microscopy, together with an 18S rDNA-based phylogeny, showed that the host is a new ciliate species closely related to Tiarina fusus (Colepidae). Phylogenetic analyses of the endosymbionts based on the 28S rDNA gene revealed multiple novel closely related Symbiodinium clade A genotypes. A haplotype network using the high-resolution internal transcribed spacer-2 marker showed that these genotypes form eight divergent, biogeographically structured, subclade types that do not seem to associate with any benthic hosts. Ecological analyses using the Tara Oceans metabarcoding data set (V9 region of the 18S rDNA) and contextual oceanographic parameters showed a global distribution of the symbiotic partnership in nutrient-poor surface waters. The discovery of the symbiotic life of Symbiodinium in the open ocean provides new insights into the ecology and evolution of this pivotal microalga and raises new hypotheses about coastal pelagic connectivity.


Asunto(s)
Biodiversidad , Cilióforos/genética , Dinoflagelados/genética , Simbiosis , Animales , Evolución Biológica , Cilióforos/fisiología , Código de Barras del ADN Taxonómico , ADN Ribosómico/química , ADN Ribosómico/genética , Dinoflagelados/fisiología , Ecología , Ecosistema , Genotipo , Geografía , Haplotipos , Metagenómica , Océanos y Mares , Filogenia
13.
Environ Microbiol ; 18(2): 609-26, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26337598

RESUMEN

Dinoflagellates (Alveolata) are one of the ecologically most important groups of modern phytoplankton. Their biological complexity makes assessment of their global diversity and community structure difficult. We used massive V9 18S rDNA sequencing from 106 size-fractionated plankton communities collected across the world's surface oceans during the Tara Oceans expedition (2009-2012) to assess patterns of pelagic dinoflagellate diversity and community structuring over global taxonomic and ecological scales. Our data and analyses suggest that dinoflagellate diversity has been largely underestimated, representing overall ∼ 1/2 of protistan rDNA metabarcode richness assigned at ≥ 90% to a reference sequence in the world's surface oceans. Dinoflagellate metabarcode diversity and abundance display regular patterns across the global scale, with different order-level taxonomic compositions across organismal size fractions. While the pico to nano-planktonic communities are composed of an extreme diversity of metabarcodes assigned to Gymnodiniales or are simply undetermined, most micro-dinoflagellate metabarcodes relate to the well-referenced Gonyaulacales and Peridiniales orders, and a lower abundance and diversity of essentially symbiotic Peridiniales is unveiled in the meso-plankton. Our analyses could help future development of biogeochemical models of pelagic systems integrating the separation of dinoflagellates into functional groups according to plankton size classes.


Asunto(s)
Código de Barras del ADN Taxonómico , Dinoflagelados/clasificación , Dinoflagelados/genética , Fitoplancton/clasificación , Fitoplancton/genética , ARN Ribosómico 18S/genética , Secuencia de Bases , Biodiversidad , ADN Ribosómico/genética , Ecología , Océanos y Mares
14.
Environ Microbiol Rep ; 7(6): 979-89, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26472079

RESUMEN

High-throughput sequencing of Prasinovirus DNA polymerase and host green algal (Mamiellophyceae) ribosomal RNA genes was used to analyse the diversity and distribution of these taxa over a ∼10 000 km latitudinal section of the Indian Ocean. New viral and host groups were identified among the different trophic conditions observed, and highlighted that although unknown prasinoviruses are diverse, the cosmopolitan algal genera Bathycoccus, Micromonas and Ostreococcus represent a large proportion of the host diversity. While Prasinovirus communities were correlated to both the geography and the environment, host communities were not, perhaps because the genetic marker used lacked sufficient resolution. Nevertheless, analysis of single environmental variables showed that eutrophic conditions strongly influence the distributions of both hosts and viruses. Moreover, these communities were not correlated, in their composition or specific richness. These observations could result from antagonistic dynamics, such as that illustrated in a prey-predator model, and/or because hosts might be under a complex set of selective pressures. Both of these reasons must be considered to interpret environmental surveys of viruses and hosts, because covariation does not always imply interaction.


Asunto(s)
Chlorophyta/genética , Chlorophyta/virología , Genotipo , Secuenciación de Nucleótidos de Alto Rendimiento , Phycodnaviridae/clasificación , Phycodnaviridae/genética , Biodiversidad , ADN Viral , Ambiente , Océano Índico , Phycodnaviridae/aislamiento & purificación
15.
Artículo en Inglés | MEDLINE | ID: mdl-26286928

RESUMEN

Microbial rhodopsins are a diverse group of photoactive transmembrane proteins found in all three domains of life and in viruses. Today, microbial rhodopsin research is a flourishing research field in which new understandings of rhodopsin diversity, function and evolution are contributing to broader microbiological and molecular knowledge. Here, we describe MicRhoDE, a comprehensive, high-quality and freely accessible database that facilitates analysis of the diversity and evolution of microbial rhodopsins. Rhodopsin sequences isolated from a vast array of marine and terrestrial environments were manually collected and curated. To each rhodopsin sequence are associated related metadata, including predicted spectral tuning of the protein, putative activity and function, taxonomy for sequences that can be linked to a 16S rRNA gene, sampling date and location, and supporting literature. The database currently covers 7857 aligned sequences from more than 450 environmental samples or organisms. Based on a robust phylogenetic analysis, we introduce an operational classification system with multiple phylogenetic levels ranging from superclusters to species-level operational taxonomic units. An integrated pipeline for online sequence alignment and phylogenetic tree construction is also provided. With a user-friendly interface and integrated online bioinformatics tools, this unique resource should be highly valuable for upcoming studies of the biogeography, diversity, distribution and evolution of microbial rhodopsins. Database URL: http://micrhode.sb-roscoff.fr.


Asunto(s)
Bacteriorodopsinas/genética , Bases de Datos de Ácidos Nucleicos , Evolución Molecular , Filogenia , ARN Ribosómico 16S , Alineación de Secuencia
16.
Environ Microbiol ; 17(10): 4035-49, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26119494

RESUMEN

Although protists are critical components of marine ecosystems, they are still poorly characterized. Here we analysed the taxonomic diversity of planktonic and benthic protist communities collected in six distant European coastal sites. Environmental deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from three size fractions (pico-, nano- and micro/mesoplankton), as well as from dissolved DNA and surface sediments were used as templates for tag pyrosequencing of the V4 region of the 18S ribosomal DNA. Beta-diversity analyses split the protist community structure into three main clusters: picoplankton-nanoplankton-dissolved DNA, micro/mesoplankton and sediments. Within each cluster, protist communities from the same site and time clustered together, while communities from the same site but different seasons were unrelated. Both DNA and RNA-based surveys provided similar relative abundances for most class-level taxonomic groups. Yet, particular groups were overrepresented in one of the two templates, such as marine alveolates (MALV)-I and MALV-II that were much more abundant in DNA surveys. Overall, the groups displaying the highest relative contribution were Dinophyceae, Diatomea, Ciliophora and Acantharia. Also, well represented were Mamiellophyceae, Cryptomonadales, marine alveolates and marine stramenopiles in the picoplankton, and Monadofilosa and basal Fungi in sediments. Our extensive and systematic sequencing of geographically separated sites provides the most comprehensive molecular description of coastal marine protist diversity to date.


Asunto(s)
Alveolados/genética , Sedimentos Geológicos/microbiología , Plancton/clasificación , Plancton/genética , Agua de Mar/microbiología , Estramenopilos/genética , Secuencia de Bases , Biodiversidad , Ecosistema , Europa (Continente) , Hongos/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Filogenia , ARN Ribosómico 18S/genética , Análisis de Secuencia de ADN
17.
Science ; 348(6237): 1261447, 2015 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-25999514

RESUMEN

Agulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic.


Asunto(s)
Plancton/fisiología , Agua de Mar , Océano Atlántico , ADN Ribosómico/genética , Variación Genética , Océano Índico , Metagenómica , Nitritos/metabolismo , Nitrógeno/metabolismo , Plancton/genética , Plancton/metabolismo , Selección Genética
18.
Science ; 348(6237): 1261605, 2015 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-25999516

RESUMEN

Marine plankton support global biological and geochemical processes. Surveys of their biodiversity have hitherto been geographically restricted and have not accounted for the full range of plankton size. We assessed eukaryotic diversity from 334 size-fractionated photic-zone plankton communities collected across tropical and temperate oceans during the circumglobal Tara Oceans expedition. We analyzed 18S ribosomal DNA sequences across the intermediate plankton-size spectrum from the smallest unicellular eukaryotes (protists, >0.8 micrometers) to small animals of a few millimeters. Eukaryotic ribosomal diversity saturated at ~150,000 operational taxonomic units, about one-third of which could not be assigned to known eukaryotic groups. Diversity emerged at all taxonomic levels, both within the groups comprising the ~11,200 cataloged morphospecies of eukaryotic plankton and among twice as many other deep-branching lineages of unappreciated importance in plankton ecology studies. Most eukaryotic plankton biodiversity belonged to heterotrophic protistan groups, particularly those known to be parasites or symbiotic hosts.


Asunto(s)
Biodiversidad , Eucariontes/clasificación , Plancton/clasificación , Animales , Código de Barras del ADN Taxonómico , ADN Ribosómico/genética , Eucariontes/genética , Océanos y Mares , Filogenia , Plancton/genética , Ribosomas/genética , Análisis de Secuencia de ADN , Luz Solar
19.
Science ; 348(6237): 1262073, 2015 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-25999517

RESUMEN

Species interaction networks are shaped by abiotic and biotic factors. Here, as part of the Tara Oceans project, we studied the photic zone interactome using environmental factors and organismal abundance profiles and found that environmental factors are incomplete predictors of community structure. We found associations across plankton functional types and phylogenetic groups to be nonrandomly distributed on the network and driven by both local and global patterns. We identified interactions among grazers, primary producers, viruses, and (mainly parasitic) symbionts and validated network-generated hypotheses using microscopy to confirm symbiotic relationships. We have thus provided a resource to support further research on ocean food webs and integrating biological components into ocean models.


Asunto(s)
Cadena Alimentaria , Plancton/clasificación , Plancton/fisiología , Simbiosis , Animales , Especificidad del Huésped , Océanos y Mares , Filogenia , Platelmintos/clasificación , Platelmintos/fisiología , Luz Solar , Virus/clasificación
20.
Mol Ecol Resour ; 15(6): 1472-85, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25828689

RESUMEN

Planktonic foraminifera (Rhizaria) are ubiquitous marine pelagic protists producing calcareous shells with conspicuous morphology. They play an important role in the marine carbon cycle, and their exceptional fossil record serves as the basis for biochronostratigraphy and past climate reconstructions. A major worldwide sampling effort over the last two decades has resulted in the establishment of multiple large collections of cryopreserved individual planktonic foraminifera samples. Thousands of 18S rDNA partial sequences have been generated, representing all major known morphological taxa across their worldwide oceanic range. This comprehensive data coverage provides an opportunity to assess patterns of molecular ecology and evolution in a holistic way for an entire group of planktonic protists. We combined all available published and unpublished genetic data to build PFR(2), the Planktonic foraminifera Ribosomal Reference database. The first version of the database includes 3322 reference 18S rDNA sequences belonging to 32 of the 47 known morphospecies of extant planktonic foraminifera, collected from 460 oceanic stations. All sequences have been rigorously taxonomically curated using a six-rank annotation system fully resolved to the morphological species level and linked to a series of metadata. The PFR(2) website, available at http://pfr2.sb-roscoff.fr, allows downloading the entire database or specific sections, as well as the identification of new planktonic foraminiferal sequences. Its novel, fully documented curation process integrates advances in morphological and molecular taxonomy. It allows for an increase in its taxonomic resolution and assures that integrity is maintained by including a complete contingency tracking of annotations and assuring that the annotations remain internally consistent.


Asunto(s)
Biodiversidad , Bases de Datos de Ácidos Nucleicos , Ecosistema , Foraminíferos/clasificación , Foraminíferos/genética , Filogeografía , Análisis por Conglomerados , ADN Protozoario/química , ADN Protozoario/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Datos de Secuencia Molecular , Plancton/clasificación , Plancton/genética , ARN Ribosómico 18S/genética , Rhizaria , Análisis de Secuencia de ADN
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