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1.
Viruses ; 10(8)2018 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-30126244

RESUMO

Prasinoviruses are large dsDNA viruses commonly found in aquatic systems worldwide, where they can infect and lyse unicellular prasinophyte algae such as Ostreococcus. Host susceptibility is virus strain-specific, but resistance of susceptible Ostreococcus tauri strains to a virulent virus arises frequently. In clonal resistant lines that re-grow, viruses are usually present for many generations, and genes clustered on chromosome 19 show physical rearrangements and differential expression. Here, we investigated changes occurring during the first two weeks after inoculation of the prasinovirus OtV5. By serial dilutions of cultures at the time of inoculation, we estimated the frequency of resistant cells arising in virus-challenged O. tauri cultures to be 10-3⁻10-4 of the inoculated population. Re-growing resistant cells were detectable by flow cytometry 3 days post-inoculation (dpi), visible re-greening of cultures occurred by 6 dpi, and karyotypic changes were visually detectable at 8 dpi. Resistant cell lines showed a modified spectrum of host-virus specificities and much lower levels of OtV5 adsorption.


Assuntos
Adaptação Fisiológica/genética , Clorófitas/genética , DNA Viral/genética , Genoma Viral , Microalgas/genética , Phycodnaviridae/crescimento & desenvolvimento , Adaptação Fisiológica/imunologia , Clorófitas/imunologia , Clorófitas/virologia , Cromossomos de Plantas/química , Cromossomos de Plantas/imunologia , DNA Viral/imunologia , Resistência à Doença/genética , Especificidade de Hospedeiro , Cariótipo , Microalgas/imunologia , Microalgas/virologia , Phycodnaviridae/patogenicidade , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/virologia , Fatores de Tempo
2.
Sci Adv ; 3(7): e1700239, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28695208

RESUMO

Tiny photosynthetic microorganisms that form the picoplankton (between 0.3 and 3 µm in diameter) are at the base of the food web in many marine ecosystems, and their adaptability to environmental change hinges on standing genetic variation. Although the genomic and phenotypic diversity of the bacterial component of the oceans has been intensively studied, little is known about the genomic and phenotypic diversity within each of the diverse eukaryotic species present. We report the level of genomic diversity in a natural population of Ostreococcus tauri (Chlorophyta, Mamiellophyceae), the smallest photosynthetic eukaryote. Contrary to the expectations of clonal evolution or cryptic species, the spectrum of genomic polymorphism observed suggests a large panmictic population (an effective population size of 1.2 × 107) with pervasive evidence of sexual reproduction. De novo assemblies of low-coverage chromosomes reveal two large candidate mating-type loci with suppressed recombination, whose origin may pre-date the speciation events in the class Mamiellophyceae. This high genetic diversity is associated with large phenotypic differences between strains. Strikingly, resistance of isolates to large double-stranded DNA viruses, which abound in their natural environment, is positively correlated with the size of a single hypervariable chromosome, which contains 44 to 156 kb of strain-specific sequences. Our findings highlight the role of viruses in shaping genome diversity in marine picoeukaryotes.


Assuntos
Cromossomos , Variação Genética , Genética Populacional , Genômica , Fitoplâncton/genética , Suscetibilidade a Doenças , Evolução Molecular , Genômica/métodos , Mutação , Fenótipo , Filogenia , Fitoplâncton/classificação , Fitoplâncton/virologia , Polimorfismo de Nucleotídeo Único , Seleção Genética
3.
Sci Data ; 4: 170093, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28763055

RESUMO

A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems.


Assuntos
Plâncton , Vírus , Ecossistema , Genômica , Nucleotídeos , Oceanos e Mares
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