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1.
Nature ; 556(7701): 339-344, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29643504

RESUMO

Large-scale population genomic surveys are essential to explore the phenotypic diversity of natural populations. Here we report the whole-genome sequencing and phenotyping of 1,011 Saccharomyces cerevisiae isolates, which together provide an accurate evolutionary picture of the genomic variants that shape the species-wide phenotypic landscape of this yeast. Genomic analyses support a single 'out-of-China' origin for this species, followed by several independent domestication events. Although domesticated isolates exhibit high variation in ploidy, aneuploidy and genome content, genome evolution in wild isolates is mainly driven by the accumulation of single nucleotide polymorphisms. A common feature is the extensive loss of heterozygosity, which represents an essential source of inter-individual variation in this mainly asexual species. Most of the single nucleotide polymorphisms, including experimentally identified functional polymorphisms, are present at very low frequencies. The largest numbers of variants identified by genome-wide association are copy-number changes, which have a greater phenotypic effect than do single nucleotide polymorphisms. This resource will guide future population genomics and genotype-phenotype studies in this classic model system.


Assuntos
Evolução Molecular , Variação Genética , Genoma Fúngico/genética , Saccharomyces cerevisiae/classificação , Saccharomyces cerevisiae/genética , Alelos , Aneuploidia , China , Variações do Número de Cópias de DNA , Estudos de Associação Genética , Estudo de Associação Genômica Ampla , Genômica , Perda de Heterozigosidade , Fenótipo , Filogenia , Filogeografia , Ploidias , Polimorfismo de Nucleotídeo Único , Saccharomyces cerevisiae/isolamento & purificação , Análise de Sequência de DNA
2.
Oncology ; 93(3): 183-190, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28571009

RESUMO

BACKGROUND: Surgery for anal canal cancer (ACC) and anal margin cancer (AMC) is the only curative option after failure of chemoradiotherapy (CRT). This study aimed to determine the efficacy of surgery for ACC or AMC after failed CRT. METHODS: This was a single-centre, retrospective study of 161 patients initially treated with CRT. We compared the survival rates of patients successfully treated by CRT with those of patients whose CRT failed (both surgically salvaged and treated palliatively). RESULTS: Thirty-one patients underwent surgery with curative intent, 20 received palliative treatment after failure of CRT, and 110 had effective CRT. The 5-year overall survival (OS) rate was significantly higher among patients with successful CRT than among patients who underwent surgery with curative intent (86 vs. 66%, p < 0.001). On the other hand, the 5-year OS of patients treated with curative surgery was significantly better than that of patients who underwent palliative treatment (66 vs. 13.5%, p < 0.001). The postoperative morbidity and mortality rates were 32 and 3%, respectively. Considering patients with failed CRT, curative surgery was the only factor prognostic of favourable OS in the multivariate analysis. CONCLUSION: Curative surgery after failure of CRT for ACC or AMC remains an effective treatment to improve survival in two-thirds of cases, resulting in high but manageable morbidity.


Assuntos
Canal Anal/patologia , Neoplasias do Ânus/cirurgia , Carcinoma de Células Escamosas/cirurgia , Quimiorradioterapia Adjuvante , Recidiva Local de Neoplasia/prevenção & controle , Complicações Pós-Operatórias/cirurgia , Terapia de Salvação , Idoso , Canal Anal/cirurgia , Neoplasias do Ânus/mortalidade , Neoplasias do Ânus/patologia , Carcinoma de Células Escamosas/mortalidade , Carcinoma de Células Escamosas/patologia , Feminino , Seguimentos , França/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/mortalidade , Complicações Pós-Operatórias/mortalidade , Complicações Pós-Operatórias/patologia , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida , Resultado do Tratamento
3.
FEMS Yeast Res ; 15(4): fov023, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25969454

RESUMO

Mitochondria are important organelles that harbor their own genomes encoding a key set of proteins that ensure respiration and provide the eukaryotic cell with energy. Recent advances in high-throughput sequencing technologies present a unique opportunity to explore mitochondrial (mt) genome evolution. The Saccharomycotina yeasts have proven to be the leading organisms for mt comparative and population genomics. In fact, the explosion of complete yeast mt genome sequences has allowed for a broader view of the mt diversity across this incredibly diverse subphylum, both within and between closely related species. Here, we summarize the present state of yeast mitogenomics, including the currently available data and what it reveals concerning the diversity of content, organization, structure and evolution of mt genomes.


Assuntos
Evolução Molecular , Variação Genética , Genoma Mitocondrial , Leveduras/genética , Genômica
4.
Int J Syst Evol Microbiol ; 65(10): 3392-3399, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26297665

RESUMO

A thorough sampling of maple, oak, birch, and apple tree bark in North America yielded a set of isolates that represent a yeast species not yet formally described. The strains obtained were all isolated from the Canadian province of Québec. These four isolates have identical electrophoretic karyotypes, distinct from other species of the genus Lachancea, and are most closely related to the formally recognized species Lachancea thermotolerans according to the D1/D2 domain of the LSU rDNA gene and 5.8S­ITS region. Previous studies revealed the existence of a population of strains closely related to L. thermotolerans, with unique D1/D2 sequences and the ability to grow on melibiose, which is also true for these isolates. The sequences obtained here (for the D1/D2, and 5.8S­ITS region) are identical among the four strains, and in a phylogenetic analysis of the D1/D2 region, the strains form a distinct clade with the previously described population closely related to L. thermotolerans, composed of isolates from Japan, as well as from the provinces of Ontario and Québec in Canada. On the basis of select physiological and phylogenetic characteristics, a novel ascosporogenous yeast species, Lachancea quebecensis sp. nov., is proposed. The type strain LL11_022T ( = CBS 14138T = CLIB 1763T = UCDFST 15-106T) was isolated from maple tree bark in the Station Duchesnay, QC region of Québec, Canada. The MycoBank number is MB811749.


Assuntos
Filogenia , Casca de Planta/microbiologia , Saccharomycetales/classificação , Acer/microbiologia , Betula/microbiologia , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Cariotipagem , Malus/microbiologia , Dados de Sequência Molecular , Técnicas de Tipagem Micológica , Quebeque , Quercus/microbiologia , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Análise de Sequência de DNA , Árvores/microbiologia
5.
Appl Environ Microbiol ; 79(19): 5997-6005, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23892741

RESUMO

The three closely related species that currently comprise the genus Salinispora were analyzed using a multilocus sequence typing approach targeting 48 strains derived from four geographic locations. Phylogenetic congruence and a well-supported concatenated tree provide strong support for the delineation of the three species as currently described and the basal relationship of Salinispora arenicola to the more recently diverged sister taxa S. tropica and S. pacifica. The phylogeny of the initial region of the rpoB gene sequenced was atypical, placing the related genera Micromonospora and Verrucosispora within the Salinispora clade. This phylogenetic incongruence was subsequently ascribed to a homologous-recombination event in a portion of the gene associated with resistance to compounds in the rifamycin class, which target RpoB. All S. arenicola strains produced compounds in this class and possessed resistance-conferring amino acid changes in RpoB. The phylogeny of a region of the rpoB gene that is not associated with rifamycin resistance was congruent with the other housekeeping genes. The link between antibiotic resistance and homologous recombination suggests that incongruent phylogenies provide opportunities to identify the molecular targets of secondary metabolites, an observation with potential relevance for drug discovery efforts. Low ratios of interspecies recombination to mutation, even among cooccurring strains, coupled with high levels of within-species recombination suggest that the three species have been described in accordance with natural barriers to recombination.


Assuntos
Farmacorresistência Bacteriana , Recombinação Homóloga , Micromonosporaceae/classificação , Micromonosporaceae/genética , Tipagem de Sequências Multilocus , Animais , Antibacterianos/farmacologia , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , RNA Polimerases Dirigidas por DNA/genética , Genótipo , Dados de Sequência Molecular , Filogenia , Rifamicinas/farmacologia , Análise de Sequência de DNA
6.
Antonie Van Leeuwenhoek ; 103(4): 809-19, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23229438

RESUMO

The Gulf of California is a coastal marine ecosystem characterized as having abundant biological resources and a high level of endemism. In this work we report the isolation and characterization of Actinobacteria from different sites in the western Gulf of California. We collected 126 sediment samples and isolated on average 3.1-38.3 Actinobacterial strains from each sample. Phylogenetic analysis of 136 strains identified them as members of the genera Actinomadura, Micromonospora, Nocardiopsis, Nonomuraea, Saccharomonospora, Salinispora, Streptomyces and Verrucosispora. These strains were grouped into 26-56 operational taxonomic units (OTUs) based on 16S rRNA gene sequence identities of 98-100 %. At 98 % sequence identity, three OTUs appear to represent new taxa while nine (35 %) have only been reported from marine environments. Sixty-three strains required seawater for growth. These fell into two OTUs at the 98 % identity level and include one that failed to produce aerial hyphae and was only distantly related (≤95.5 % 16S identity) to any previously cultured Streptomyces sp. Phylogenetic analyses of ketosynthase domains associated with polyketide synthase genes revealed sequences that ranged from 55 to 99 % nucleotide identity to experimentally characterized biosynthetic pathways suggesting that some may be associated with the production of new secondary metabolites. These results indicate that marine sediments from the Gulf of California harbor diverse Actinobacterial taxa with the potential to produce new secondary metabolites.


Assuntos
Actinobacteria/classificação , Actinobacteria/metabolismo , Biodiversidade , Produtos Biológicos/análise , Sedimentos Geológicos/microbiologia , Actinobacteria/isolamento & purificação , California , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , Policetídeo Sintases/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
Antonie Van Leeuwenhoek ; 103(5): 1069-78, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23361994

RESUMO

A polyphasic analysis was carried out to clarify the taxonomic status of four marine actinomycete strains that share a phylogenetic relationship and phenotypic characteristics with the genus Salinispora. These strains formed a distinct lineage within the Salinispora 16S rRNA and gyrB trees and were found to possess a range of phenotypic properties and DNA:DNA hybridization values that distinguished them from the type strains of the two validly named species in this genus, Salinispora tropica (CNB-440(T), ATCC BAA-916(T)) and Salinispora arenicola (CNH-643(T), ATCC BAA-917(T)). The combined genotypic and phenotypic data support this conclusion. It is proposed that the strains be designated as Salinispora pacifica sp. nov., the type strain of which is CNR-114(T) (DSMZ YYYYT = KACC 17160(T)).


Assuntos
Sedimentos Geológicos/microbiologia , Micromonosporaceae/classificação , Micromonosporaceae/isolamento & purificação , Técnicas de Tipagem Bacteriana , Análise por Conglomerados , DNA Girase/genética , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Guam , Micromonosporaceae/genética , Micromonosporaceae/fisiologia , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Palau , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
8.
Genome Biol Evol ; 15(2)2023 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-36634937

RESUMO

The process of domestication has variable consequences on genome evolution leading to different phenotypic signatures. Access to the complete genome sequences of a large number of individuals makes it possible to explore the different facets of this domestication process. Here, we sought to explore the genome evolution of Kluyveromyces lactis, a yeast species well known for its involvement in dairy processes and also present in natural environments. Using a combination of short- and long-read sequencing strategies, we investigated the genomic variability of 41 K. lactis isolates and found that the overall genetic diversity of this species is very high (θw = 3.3 × 10-2) compared with other species such as Saccharomyces cerevisiae (θw = 1.6 × 10-2). However, the domesticated dairy population shows a reduced level of diversity (θw = 1 × 10-3), probably due to a domestication bottleneck. In addition, this entire population is characterized by the introgression of the LAC4 and LAC12 genes, responsible for lactose fermentation and coming from the closely related species, Kluyveromyces marxianus, as previously described. Our results highlighted that the LAC4/LAC12 gene cluster was acquired through multiple and independent introgression events. Finally, we also identified several genes that could play a role in adaptation to dairy environments through copy number variation. These genes are involved in sugar consumption, flocculation, and drug resistance, and may play a role in dairy processes. Overall, our study illustrates contrasting genomic evolution and sheds new light on the impact of domestication processes on it.


Assuntos
Variações do Número de Cópias de DNA , Saccharomyces cerevisiae , Humanos , Saccharomyces cerevisiae/genética , Genômica , Evolução Molecular
9.
Environ Microbiol ; 14(2): 480-93, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22117917

RESUMO

In July of 2006 and January of 2008, a total of 671 marine sediment samples were collected at depths from 5 to 2012 m throughout the Fijian islands and selectively processed for the cultivation of marine actinomycetes belonging to the genus Salinispora. The primary objectives were to assess the diversity, distribution and phylogeny of 'S. pacifica', the least well studied of the three species in the genus. Employing a sequential screening method based on antibiotic sensitivity, RFLP patterns, and 16S rRNA and ITS sequence analyses, 42 of 750 isolates with Salinispora-like features were identified as 'S. pacifica'. These strains represent the first report of 'S. pacifica' from Fiji and include 15 representatives of 4 new 'S. pacifica' 16S rRNA sequence types. Among the 'S. pacifica' strains isolated, little evidence for geographical isolation emerged based on 16S, ITS or secondary metabolite biosynthetic gene fingerprinting. The inclusion of isolates from additional collection sites and other Salinispora spp. revealed a high degree of dispersal among 'S. pacifica' populations and phylogenetic support for the delineation of this lineage as a third species.


Assuntos
Micromonosporaceae/classificação , Microbiologia da Água , Fiji , Variação Genética , Sedimentos Geológicos/microbiologia , Micromonosporaceae/genética , Micromonosporaceae/metabolismo , Dados de Sequência Molecular , Filogenia , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Água do Mar/microbiologia
10.
Appl Environ Microbiol ; 77(20): 7261-70, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21873479

RESUMO

The marine actinomycete genus Salinispora is composed of three closely related species. These bacteria are a rich source of secondary metabolites, which are produced in species-specific patterns. This study examines the distribution and phylogenetic relationships of genes involved in the biosynthesis of secondary metabolites in the salinosporamide and staurosporine classes, which have been reported for S. tropica and S. arenicola, respectively. The focus is on "Salinispora pacifica," the most recently discovered and phylogenetically diverse member of the genus. Of 61 S. pacifica strains examined, 15 tested positive for a ketosynthase (KS) domain linked to the biosynthesis of salinosporamide K, a new compound in the salinosporamide series. Compound production was confirmed in two strains, and the domain phylogeny supports vertical inheritance from a common ancestor shared with S. tropica, which produces related compounds in the salinosporamide series. There was no evidence for interspecies recombination among salA KS sequences, providing further support for the geographic isolation of these two salinosporamide-producing lineages. In addition, staurosporine production is reported for the first time for S. pacifica, with 24 of 61 strains testing positive for staD, a key gene involved in the biosynthesis of this compound. High levels of recombination were observed between staD alleles in S. pacifica and the cooccurring yet more distantly related S. arenicola, which produces a similar series of staurosporines. The distributions and phylogenies of the biosynthetic genes examined provide insight into the complex processes driving the evolution of secondary metabolism among closely related bacterial species.


Assuntos
Vias Biossintéticas/genética , Genes Bacterianos , Micromonosporaceae/genética , Água do Mar/microbiologia , Alcaloides/biossíntese , Proteínas de Bactérias/genética , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Lactonas/metabolismo , Micromonosporaceae/isolamento & purificação , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
11.
Appl Environ Microbiol ; 77(11): 3617-25, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21498757

RESUMO

Bacteria of the genus Frankia are mycelium-forming actinomycetes that are found as nitrogen-fixing facultative symbionts of actinorhizal plants. Although soil-dwelling actinomycetes are well-known producers of bioactive compounds, the genus Frankia has largely gone uninvestigated for this potential. Bioinformatic analysis of the genome sequences of Frankia strains ACN14a, CcI3, and EAN1pec revealed an unexpected number of secondary metabolic biosynthesis gene clusters. Our analysis led to the identification of at least 65 biosynthetic gene clusters, the vast majority of which appear to be unique and for which products have not been observed or characterized. More than 25 secondary metabolite structures or structure fragments were predicted, and these are expected to include cyclic peptides, siderophores, pigments, signaling molecules, and specialized lipids. Outside the hopanoid gene locus, no cluster could be convincingly demonstrated to be responsible for the few secondary metabolites previously isolated from other Frankia strains. Few clusters were shared among the three species, demonstrating species-specific biosynthetic diversity. Proteomic analysis of Frankia sp. strains CcI3 and EAN1pec showed that significant and diverse secondary metabolic activity was expressed in laboratory cultures. In addition, several prominent signals in the mass range of peptide natural products were observed in Frankia sp. CcI3 by intact-cell matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). This work supports the value of bioinformatic investigation in natural products biosynthesis using genomic information and presents a clear roadmap for natural products discovery in the Frankia genus.


Assuntos
Produtos Biológicos/biossíntese , Vias Biossintéticas/genética , Frankia/genética , Frankia/metabolismo , Genômica , Proteômica , Família Multigênica
12.
PeerJ ; 9: e12274, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34760357

RESUMO

Surveys of microbial communities across transitions coupled with contextual measures of the environment provide a useful approach to dissect the factors determining distributions of microorganisms across ecological niches. Here, monthly time-series samples of surface seawater along a transect spanning the nearshore coastal environment within Kane'ohe Bay on the island of O'ahu, Hawai'i, and the adjacent offshore environment were collected to investigate the diversity and abundance of SAR11 marine bacteria (order Pelagibacterales) over a 2-year time period. Using 16S ribosomal RNA gene amplicon sequencing, the spatiotemporal distributions of major SAR11 subclades and exact amplicon sequence variants (ASVs) were evaluated. Seven of eight SAR11 subclades detected in this study showed distinct subclade distributions across the coastal to offshore environments. The SAR11 community was dominated by seven (of 106 total) SAR11 ASVs that made up an average of 77% of total SAR11. These seven ASVs spanned five different SAR11 subclades (Ia, Ib, IIa, IV, and Va), and were recovered from all samples collected from either the coastal environment, the offshore, or both. SAR11 ASVs were more often restricted spatially to coastal or offshore environments (64 of 106 ASVs) than they were shared among coastal, transition, and offshore environments (39 of 106 ASVs). Overall, offshore SAR11 communities contained a higher diversity of SAR11 ASVs than their nearshore counterparts, with the highest diversity within the little-studied subclade IIa. This study reveals ecological differentiation of SAR11 marine bacteria across a short physiochemical gradient, further increasing our understanding of how SAR11 genetic diversity partitions into distinct ecological units.

13.
mSystems ; 5(6)2020 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-33361323

RESUMO

While marine microorganisms are frequently studied in their natural environment, isolated strains are invaluable resources that can be used in controlled experiments to expand upon direct observations from natural systems. Here, we sought a means to enhance culture collections of SAR11 marine bacteria by testing the use of seawater cryopreserved with glycerol as an inoculum. Using a raw seawater sample collected from the tropical Pacific Ocean, a subsample was diluted in seawater growth medium to create 576 2-ml dilution cultures containing 5 cells each and incubated for a high-throughput culturing (HTC) experiment, while another portion was cryopreserved in 10% glycerol. After 10 months, a cryopreserved aliquot was thawed and used to create a second cultivation experiment of 480 2-ml cultures containing 5 cells each and 470 cultures containing 105 cells each. The raw seawater cultivation experiment resulted in the successful isolation of 54 monocultures and 29 mixed cultures, while cryopreserved seawater resulted in 59 monocultures and 29 mixed cultures. Combined, the cultures included 51 SAR11 isolates spanning 11 unique 16S rRNA gene amplicon sequence variants (ASVs) from the raw seawater inoculum and 74 SAR11 isolates spanning 13 unique ASVs from cryopreserved seawater. A vast majority (92%) of SAR11 isolates from the two HTC experiments were members of SAR11 subclade Ia, though subclades IIIa and Va were also recovered from cryopreserved seawater and subclade Ib was recovered from both. The four most abundant SAR11 subclade Ia ASVs found in the initial seawater environmental sample were isolated by both approaches.IMPORTANCE High-throughput dilution culture has proved to be a successful approach to bring some difficult-to-isolate planktonic microorganisms into culture, including the highly abundant SAR11 lineage of marine bacteria. While the long-term preservation of bacterial isolates by freezing them in the presence of cryoprotectants, such as glycerol, has been shown to be an effective method of storing viable cells over long time periods (i.e., years), to our knowledge it had not previously been tested for its efficacy in preserving raw seawater for later use as an inoculum for high-throughput cultivation experiments. We found that SAR11 and other abundant marine bacteria could be isolated from seawater that was previously cryopreserved for nearly 10 months at a rate of culturability similar to that of the same seawater used fresh, immediately after collection. Our findings (i) expand the potential of high-throughput cultivation experiments to include testing when immediate isolation experiments are impractical, (ii) allow for targeted isolation experiments from specific samples based on analyses such as microbial community structure, and (iii) enable cultivation experiments across a wide range of other conditions that would benefit from having source inocula available over extended periods of time.

14.
Genome Biol Evol ; 12(6): 795-807, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32302403

RESUMO

Genome-wide characterization of genetic variants of a large population of individuals within the same species is essential to have a deeper insight into its evolutionary history as well as the genotype-phenotype relationship. Population genomic surveys have been performed in multiple yeast species, including the two model organisms, Saccharomyces cerevisiae and Schizosaccharomyces pombe. In this context, we sought to characterize at the population level the Brettanomyces bruxellensis yeast species, which is a major cause of wine spoilage and can contribute to the specific flavor profile of some Belgium beers. We have completely sequenced the genome of 53 B. bruxellensis strains isolated worldwide. The annotation of the reference genome allowed us to define the gene content of this species. As previously suggested, our genomic data clearly highlighted that genetic diversity variation is related to ploidy level, which is variable in the B. bruxellensis species. Genomes are punctuated by multiple loss-of-heterozygosity regions, whereas aneuploidies as well as segmental duplications are uncommon. Interestingly, triploid genomes are more prone to gene copy number variation than diploids. Finally, the pangenome of the species was reconstructed and was found to be small with few accessory genes compared with S. cerevisiae. The pangenome is composed of 5,409 ORFs (open reading frames) among which 5,106 core ORFs and 303 ORFs that are variable within the population. All these results highlight the different trajectories of species evolution and consequently the interest of establishing population genomic surveys in more populations.


Assuntos
Brettanomyces/genética , Variação Genética , Genoma Fúngico , Ploidias , Perda de Heterozigosidade , Filogenia , Sequenciamento Completo do Genoma
15.
Microb Genom ; 6(10)2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33034553

RESUMO

Thiomonas bacteria are ubiquitous at acid mine drainage sites and play key roles in the remediation of water at these locations by oxidizing arsenite to arsenate, favouring the sorption of arsenic by iron oxides and their coprecipitation. Understanding the adaptive capacities of these bacteria is crucial to revealing how they persist and remain active in such extreme conditions. Interestingly, it was previously observed that after exposure to arsenite, when grown in a biofilm, some strains of Thiomonas bacteria develop variants that are more resistant to arsenic. Here, we identified the mechanisms involved in the emergence of such variants in biofilms. We found that the percentage of variants generated increased in the presence of high concentrations of arsenite (5.33 mM), especially in the detached cells after growth under biofilm-forming conditions. Analysis of gene expression in the parent strain CB2 revealed that genes involved in DNA repair were upregulated in the conditions where variants were observed. Finally, we assessed the phenotypes and genomes of the subsequent variants generated to evaluate the number of mutations compared to the parent strain. We determined that multiple point mutations accumulated after exposure to arsenite when cells were grown under biofilm conditions. Some of these mutations were found in what is referred to as ICE19, a genomic island (GI) carrying arsenic-resistance genes, also harbouring characteristics of an integrative and conjugative element (ICE). The mutations likely favoured the excision and duplication of this GI. This research aids in understanding how Thiomonas bacteria adapt to highly toxic environments, and, more generally, provides a window to bacterial genome evolution in extreme environments.


Assuntos
Arsenitos/metabolismo , Biofilmes/crescimento & desenvolvimento , Burkholderiales , Genoma Bacteriano/genética , Adaptação Fisiológica/genética , Arseniatos/metabolismo , Arsênio/metabolismo , Burkholderiales/genética , Burkholderiales/crescimento & desenvolvimento , Burkholderiales/metabolismo , Reparo do DNA/genética , Elementos de DNA Transponíveis/genética , Evolução Molecular , Perfilação da Expressão Gênica , Variação Genética/genética , Ilhas Genômicas/genética , Mineração , Sequenciamento Completo do Genoma
16.
J Nat Prod ; 72(3): 396-402, 2009 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-19117399

RESUMO

Three new cyclohexadepsipeptides, arenamides A-C (1-3), were isolated from the fermentation broth of a marine bacterial strain identified as Salinispora arenicola. The planar structures of these compounds were assigned by detailed interpretation of NMR and MS/MS spectroscopic data. The absolute configurations of the amino acids, and those of the chiral centers on the side chain, were established by application of the Marfey and modified Mosher methods. The effect of arenamides A and B on NFkappaB activity was studied with stably transfected 293/NFkappaB-Luc human embryonic kidney cells induced by treatment with tumor necrosis factor (TNF). Arenamides A (1) and B (2) blocked TNF-induced activation in a dose- and time-dependent manner with IC(50) values of 3.7 and 1.7 microM, respectively. In addition, the compounds inhibited nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production with lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Moderate cytotoxicity was observed with the human colon carcinoma cell line HCT-116, but no cytotoxic effect was noted with cultured RAW cells. Taken together, these data suggest that the chemoprevention and anti-inflammatory characteristics of arenamides A and B warrant further investigation.


Assuntos
Actinobacteria/química , Anti-Inflamatórios não Esteroides/isolamento & purificação , Anti-Inflamatórios não Esteroides/farmacologia , Depsipeptídeos/isolamento & purificação , Depsipeptídeos/farmacologia , NF-kappa B/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Anti-Inflamatórios não Esteroides/química , Depsipeptídeos/química , Dinoprostona/antagonistas & inibidores , Dinoprostona/metabolismo , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HCT116 , Humanos , Concentração Inibidora 50 , Rim/citologia , Rim/efeitos dos fármacos , Rim/embriologia , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Biologia Marinha , Camundongos , Estrutura Molecular , NF-kappa B/metabolismo , Óxido Nítrico/biossíntese , Ressonância Magnética Nuclear Biomolecular , Fator de Necrose Tumoral alfa/farmacologia
17.
Front Microbiol ; 10: 1679, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31396189

RESUMO

The yeast Candida glabrata is a major opportunistic pathogen causing mucosal and systemic infections in humans. Systemic infections caused by this yeast have high mortality rates and are difficult to treat due to this yeast's intrinsic and frequently adapting antifungal resistance. To understand and treat C. glabrata infections, it is essential to investigate the molecular basis of C. glabrata virulence and resistance. We established an RNA interference (RNAi) system in C. glabrata by expressing the Dicer and Argonaute genes from Saccharomyces castellii (a budding yeast with natural RNAi). Our experiments with reporter genes and putative virulence genes showed that the introduction of RNAi resulted in 30 and 70% gene-knockdown for the construct-types antisense and hairpin, respectively. The resulting C. glabrata RNAi strain was used for the screening of a gene library for new virulence-related genes. Phenotypic profiling with a high-resolution quantification of growth identified genes involved in the maintenance of cell integrity, antifungal drugs, and ROS resistance. The genes identified by this approach are promising targets for the treatment of C. glabrata infections.

19.
Environ Sci Pollut Res Int ; 25(2): 1470-1483, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29090447

RESUMO

Several studies have suggested the existence of a close relationship between antibiotic-resistant phenotypes and resistance to other toxic compounds such as heavy metals, which involve co-resistance or cross-resistance mechanisms. A metagenomic library was previously constructed in Escherichia coli with DNA extracted from the bacterial community inhabiting an acid mine drainage (AMD) site highly contaminated with heavy metals. Here, we conducted a search for genes involved in antibiotic resistance using this previously constructed library. In particular, resistance to antibiotics was observed among five clones carrying four different loci originating from CARN5 and CARN2, two genomes reconstructed from the metagenomic data. Among the three CARN2 loci, two carry genes homologous to those previously proposed to be involved in antibiotic resistance. The third CARN2 locus carries a gene encoding a membrane transporter with an unknown function and was found to confer bacterial resistance to rifampicin, gentamycin, and kanamycin. The genome of Thiomonas delicata DSM 16361 and Thiomonas sp. X19 were sequenced in this study. Homologs of genes carried on these three CARN2 loci were found in these genomes, two of these loci were found in genomic islands. Together, these findings confirm that AMD environments contaminated with several toxic metals also constitute habitats for bacteria that function as reservoirs for antibiotic resistance genes.


Assuntos
Adaptação Biológica/genética , Resistência Microbiana a Medicamentos/genética , Genômica , Mineração , Águas Residuárias/microbiologia , Ácidos/farmacologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/genética , Bases de Dados Genéticas , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Metais Pesados/farmacologia
20.
G3 (Bethesda) ; 7(10): 3243-3250, 2017 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-28983066

RESUMO

Genetic variation in natural populations represents the raw material for phenotypic diversity. Species-wide characterization of genetic variants is crucial to have a deeper insight into the genotype-phenotype relationship. With the advent of new sequencing strategies and more recently the release of long-read sequencing platforms, it is now possible to explore the genetic diversity of any nonmodel organisms, representing a fundamental resource for biological research. In the frame of population genomic surveys, a first step is to obtain the complete sequence and high-quality assembly of a reference genome. Here, we sequenced and assembled a reference genome of the nonconventional Dekkera bruxellensis yeast. While this species is a major cause of wine spoilage, it paradoxically contributes to the specific flavor profile of some Belgium beers. In addition, an extreme karyotype variability is observed across natural isolates, highlighting that D. bruxellensis genome is very dynamic. The whole genome of the D. bruxellensis UMY321 isolate was sequenced using a combination of Nanopore long-read and Illumina short-read sequencing data. We generated the most complete and contiguous de novo assembly of D. bruxellensis to date and obtained a first glimpse into the genomic variability within this species by comparing the sequences of several isolates. This genome sequence is therefore of high value for population genomic surveys and represents a reference to study genome dynamic in this yeast species.


Assuntos
Dekkera/genética , Genoma Fúngico , Análise de Sequência de DNA/métodos
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