RESUMO
Motivation: High-quality phylogenetic placement of sequence data has the potential to greatly accelerate studies of the diversity, systematics, ecology and functional biology of diverse groups. We developed the Tree-Based Alignment Selector (T-BAS) toolkit to allow evolutionary placement and visualization of diverse DNA sequences representing unknown taxa within a robust phylogenetic context, and to permit the downloading of highly curated, single- and multi-locus alignments for specific clades. Results: In its initial form, T-BAS v1.0 uses a core phylogeny of 979 taxa (including 23 outgroup taxa, as well as 61 orders, 175 families and 496 genera) representing all 13 classes of largest subphylum of Fungi-Pezizomycotina (Ascomycota)-based on sequence alignments for six loci (nr5.8S, nrLSU, nrSSU, mtSSU, RPB1, RPB2 ). T-BAS v1.0 has three main uses: (i) Users may download alignments and voucher tables for members of the Pezizomycotina directly from the reference tree, facilitating systematics studies of focal clades. (ii) Users may upload sequence files with reads representing unknown taxa and place these on the phylogeny using either BLAST or phylogeny-based approaches, and then use the displayed tree to select reference taxa to include when downloading alignments. The placement of unknowns can be performed for large numbers of Sanger sequences obtained from fungal cultures and for alignable, short reads of environmental amplicons. (iii) User-customizable metadata can be visualized on the tree. Availability and Implementation: T-BAS Version 1.0 is available online at http://tbas.hpc.ncsu.edu . Registration is required to access the CIPRES Science Gateway and NSF XSEDE's large computational resources. Contact: icarbon@ncsu.edu. Supplementary information: Supplementary data are available at Bioinformatics online.
Assuntos
Ascomicetos/genética , Metadados , Filogenia , Alinhamento de Sequência/métodos , Software , Endófitos/fisiologia , Loci GênicosRESUMO
BACKGROUND: Fludarabine-based chemoimmunotherapy with rituximab is frequently used in patients with indolent and mantle-cell lymphomas who relapse after alkylating chemotherapy. We aimed to compare the efficacy and safety of rituximab with bendamustine or fludarabine in patients with relapsed, indolent, non-Hodgkin lymphoma and mantle-cell lymphoma. METHODS: For this randomised, non-inferiority, open-label, phase 3 trial, we recruited patients from 55 centres in Germany, who were subsequently randomised centrally according to prespecified randomisation lists with permuted blocks of randomly variable block size to rituximab (375 mg/m(2), day 1) plus either bendamustine (90 mg/m(2), days 1 and 2) or fludarabine (25 mg/m(2), days 1-3) every 28 days for a maximum of six 28-day cycles. Patients were aged 18 years or older with a WHO performance status of 0-2 and had relapsed or refractory indolent or mantle-cell lymphoma; patients refractory to regimens that included rituximab, bendamustine, or purine analogue drugs were excluded. Patients were stratified by histological subtypes of lymphoma and by their latest previous therapies. Treatment allocation was not masked. The primary endpoint was progression-free survival and the final analysis was completed per protocol. Non-inferiority of bendamustine plus rituximab versus fludarabine plus rituximab was defined as a difference of less than 15% in 1-year progression-free survival. The protocol was amended in July, 2006, after approval of rituximab maintenance (375 mg/m(2) every 3 months for up to 2 years), which was then given to patients achieving a response to either trial treatment. This study is registered with ClinicalTrials.gov, number NCT01456351 (closed to enrolment, follow-up is ongoing). FINDINGS: Between Oct 8, 2003, and Aug 5, 2010, we randomly assigned 230 patients to treatment groups (116 bendamustine plus rituximab, 114 fludarabine plus rituximab). 11 patients were excluded for protocol violations and were not followed up further (two in the bendamustine plus rituximab group and nine in the fludarabine plus rituximab group). Thus, 219 patients were included in the per-protocol analysis (114 bendamustine plus rituximab, 105 fludarabine plus rituximab). 1-year progression-free survival with bendamustine plus rituximab was 0·76 (95% CI 0·68-0·84) and 0·48 (0·39-0·58) with fludarabine plus rituximab (non-inferiority p<0·0001). At a median follow-up of 96 months (IQR 73·2-112·9), median progression-free survival with bendamustine plus rituximab was 34·2 months (95% CI 23·5-52·7) and 11·7 months (8·0-16·1) with fludarabine plus rituximab (hazard ratio [HR] 0·54 [95% CI 0·38-0·72], log-rank test p<0·0001). Safety outcomes were similar in both groups, with 46 serious adverse events recorded (23 in the bendamustine plus rituximab group and 23 in the fludarabine plus rituximab group), most commonly myelosuppression and infections. INTERPRETATION: In combination with rituximab, bendamustine was more effective than fludarabine, suggesting that bendamustine plus rituximab may be the preferred treatment option for patients with relapsed indolent and mantle-cell lymphomas. FUNDING: Roche Pharma AG, Ribosepharm GmbH, Mundipharma GmbH, Studiengruppe indolente Lymphome (StiL).
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Linfoma de Célula do Manto/tratamento farmacológico , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Cloridrato de Bendamustina/administração & dosagem , Cloridrato de Bendamustina/efeitos adversos , Intervalo Livre de Doença , Feminino , Humanos , Infecções/induzido quimicamente , Masculino , Pessoa de Meia-Idade , Recidiva , Retratamento , Rituximab/administração & dosagem , Rituximab/efeitos adversos , Taxa de Sobrevida , Resultado do Tratamento , Vidarabina/administração & dosagem , Vidarabina/efeitos adversos , Vidarabina/análogos & derivadosRESUMO
Reconstructing the evolutionary relationships of species is a major goal in biology. Despite the increasing number of completely sequenced genomes, a large number of phylogenetic projects rely on targeted sequencing and analysis of a relatively small sample of marker genes. The selection of these phylogenetic markers should ideally be based on accurate predictions of their combined, rather than individual, potential to accurately resolve the phylogeny of interest. Here we present and validate a new phylogenomics strategy to efficiently select a minimal set of stable markers able to reconstruct the underlying species phylogeny. In contrast to previous approaches, our methodology does not only rely on the ability of individual genes to reconstruct a known phylogeny, but it also explores the combined power of sets of concatenated genes to accurately infer phylogenetic relationships of species not previously analyzed. We applied our approach to two broad sets of cyanobacterial and ascomycetous fungal species, and provide two minimal sets of six and four genes, respectively, necessary to fully resolve the target phylogenies. This approach paves the way for the informed selection of phylogenetic markers in the effort of reconstructing the tree of life.
Assuntos
Genômica/métodos , Filogenia , Ascomicetos/classificação , Ascomicetos/genética , Cianobactérias/classificação , Cianobactérias/genética , Genes Bacterianos , Genes Fúngicos , Marcadores GenéticosRESUMO
Nucleotide positions in the hypervariable V4 and V9 regions of the small subunit (SSU)-rDNA locus are normally difficult to align and are usually removed before standard phylogenetic analyses. Yet, with next-generation sequencing data, amplicons of these regions are all that are available to answer ecological and evolutionary questions that rely on phylogenetic inferences. With ciliates, we asked how inclusion of the V4 or V9 regions, regardless of alignment quality, affects tree topologies using distinct phylogenetic methods (including PairDist that is introduced here). Results show that the best approach is to place V4 amplicons into an alignment of full-length Sanger SSU-rDNA sequences and to infer the phylogenetic tree with RAxML. A sliding window algorithm as implemented in RAxML shows, though, that not all nucleotide positions in the V4 region are better than V9 at inferring the ciliate tree. With this approach and an ancestral-state reconstruction, we use V4 amplicons from European nearshore sampling sites to infer that rather than being primarily terrestrial and freshwater, colpodean ciliates may have repeatedly transitioned from terrestrial/freshwater to marine environments.
Assuntos
Cilióforos/genética , Microbiologia da Água , Teorema de Bayes , DNA Espaçador Ribossômico/genética , Evolução Molecular , Água Doce/microbiologia , Genes de Protozoários , Especiação Genética , Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala , Modelos Genéticos , Filogenia , Subunidades Ribossômicas Menores/genética , Água do Mar/microbiologia , Análise de Sequência de DNARESUMO
The Lecanoromycetes is the largest class of lichenized Fungi, and one of the most species-rich classes in the kingdom. Here we provide a multigene phylogenetic synthesis (using three ribosomal RNA-coding and two protein-coding genes) of the Lecanoromycetes based on 642 newly generated and 3329 publicly available sequences representing 1139 taxa, 317 genera, 66 families, 17 orders and five subclasses (four currently recognized: Acarosporomycetidae, Lecanoromycetidae, Ostropomycetidae, Umbilicariomycetidae; and one provisionarily recognized, 'Candelariomycetidae'). Maximum likelihood phylogenetic analyses on four multigene datasets assembled using a cumulative supermatrix approach with a progressively higher number of species and missing data (5-gene, 5+4-gene, 5+4+3-gene and 5+4+3+2-gene datasets) show that the current classification includes non-monophyletic taxa at various ranks, which need to be recircumscribed and require revisionary treatments based on denser taxon sampling and more loci. Two newly circumscribed orders (Arctomiales and Hymeneliales in the Ostropomycetidae) and three families (Ramboldiaceae and Psilolechiaceae in the Lecanorales, and Strangosporaceae in the Lecanoromycetes inc. sed.) are introduced. The potential resurrection of the families Eigleraceae and Lopadiaceae is considered here to alleviate phylogenetic and classification disparities. An overview of the photobionts associated with the main fungal lineages in the Lecanoromycetes based on available published records is provided. A revised schematic classification at the family level in the phylogenetic context of widely accepted and newly revealed relationships across Lecanoromycetes is included. The cumulative addition of taxa with an increasing amount of missing data (i.e., a cumulative supermatrix approach, starting with taxa for which sequences were available for all five targeted genes and ending with the addition of taxa for which only two genes have been sequenced) revealed relatively stable relationships for many families and orders. However, the increasing number of taxa without the addition of more loci also resulted in an expected substantial loss of phylogenetic resolving power and support (especially for deep phylogenetic relationships), potentially including the misplacements of several taxa. Future phylogenetic analyses should include additional single copy protein-coding markers in order to improve the tree of the Lecanoromycetes. As part of this study, a new module ("Hypha") of the freely available Mesquite software was developed to compare and display the internodal support values derived from this cumulative supermatrix approach.
Assuntos
Ascomicetos/classificação , Filogenia , Ascomicetos/genética , Núcleo Celular/genética , Genes Fúngicos , Genes Mitocondriais , Funções Verossimilhança , Modelos Genéticos , RNA Ribossômico/genética , Alinhamento de Sequência , Análise de Sequência de DNA , SoftwareRESUMO
Biological soil crusts (BSCs) are communities of cryptogamic organisms, occurring in arid and semiarid regions all over the world. Based on both morphological identification and genetic analyses, we established a first cyanobacterial inventory using the biphasic approach for BSCs within two major biomes of southern Africa. The samples were collected at two different sites in the Succulent Karoo and one in the Nama Karoo. After cultivation and morphological identification, the 16S rRNA gene was sequenced from the cyanobacterial cultures. From the soil samples, the DNA was extracted, and the 16S rRNA gene sequenced. All the sequences of the clone libraries from soil and cultures were compared with those of the public databases. Forty-five different species were morphologically identified in the samples of the Succulent Karoo (observatories of Soebatsfontein and Goedehoop). Based on the genetic analyses, 60 operational taxonomic units (OTUs) were identified for the Succulent Karoo and 43 for the Nama Karoo (based on 95% sequence similarity). The cloned sequences corresponded well with the morphologically described taxa in cultures and sequences in the public databases. Besides known species of typical crust-forming cyanobacterial genera (Microcoleus, Phormidium, Tolypothrix and Scytonema), we found sequences of so far undescribed species of the genera Leptolyngbya, Pseudanabaena, Phormidium, Oscillatoria, Schizothrix and Microcoleus. Most OTUs were restricted to distinct sites. Grazed soils showed lower taxa numbers than undisturbed soils, implying the presence of early successional crust types and reduced soil surface protection. Our combined approach of morphological identification and genetic analyses allowed both a taxa inventory and the analysis of species occurring under specific habitat conditions.
Assuntos
Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Genótipo , Fenótipo , Microbiologia do Solo , África Austral , Biodiversidade , Clonagem Molecular , Cianobactérias/genética , DNA Bacteriano/genética , Ecossistema , RNA Ribossômico 16S/genéticaRESUMO
The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations, which are differentially distributed according to their host preference and adaptation to chemical treatments.
Assuntos
Biota , Farmacorresistência Fúngica , Fungos/classificação , Fungos/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Microbiologia do Solo , DNA Fúngico/química , DNA Fúngico/genética , Fragaria/crescimento & desenvolvimento , Fungos/genética , Fungos/isolamento & purificação , Alemanha , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
Molecular diversity surveys of marine fungi have demonstrated that the species richness known to date is just the tip of the iceberg and that there is a large extent of unknown fungal diversity in marine habitats. Reports of novel fungal lineages at higher taxonomic levels are documented from a large number of marine habitats, including the various marine oxygen-deficient environments (ODEs). In the past few years, a strong focus of eukaryote diversity research has been on a variety of ODEs, as these environments are considered to harbor a large number of organisms, which are highly divergent to known diversity and could provide insights into the early eukaryotic evolution. ODEs that have been targeted so far include shallow water sediments, hydrothermal vent systems, deep-sea basins, intertidal habitats, and fjords. Most, if not all, molecular diversity studies in marine ODEs have shown, that contrary to previous assumptions, fungi contribute significantly to the micro-eukaryotic community in such habitats. In this chapter, we have reanalyzed the environmental fungal sequences obtained from the molecular diversity survey in 14 different sites to obtain a comprehensive picture of fungal diversity in these marine habitats. The phylogenetic analysis of the fungal environmental sequences from various ODEs have grouped these sequences into seven distinct clades (Clade 1-7) clustering with well-known fungal taxa. Apart from this, four environmental clades (EnvClade A, B, C, and D) with exclusive environmental sequences were also identified. This has provided information on the positioning of the environmental sequences at different taxonomic levels within the major fungal phylums. The taxonomic distribution of these environmental fungal sequences into clusters and clades has also shown that they are not restricted by geographical boundaries. The distribution pattern together with the reports on the respiratory abilities of fungi under reduced oxygen conditions shows that they are highly adaptive and may have a huge ecological role in these oxygen deficient habitats.
Assuntos
Oxigênio , Filogenia , Ecossistema , Eucariotos , Evolução Molecular , Fungos/classificação , Dados de Sequência MolecularRESUMO
The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.
Assuntos
Evolução Molecular , Fungos/genética , Genes Fúngicos/genética , Filogenia , Quitridiomicetos/classificação , Quitridiomicetos/genética , Fungos/classificação , Microsporídios/classificação , Microsporídios/genéticaRESUMO
YidC/Oxa/Alb3 family proteins catalyze the insertion of integral membrane proteins in bacteria, mitochondria, and chloroplasts, respectively. Unlike gram-negative organisms, gram-positive bacteria express 2 paralogs of this family, YidC1/SpoIIIJ and YidC2/YgjG. In Streptococcus mutans, deletion of yidC2 results in a stress-sensitive phenotype similar to that of mutants lacking the signal recognition particle (SRP) protein translocation pathway, while deletion of yidC1 has a less severe phenotype. In contrast to eukaryotes and gram-negative bacteria, SRP-deficient mutants are viable in S. mutans; however, double SRP-yidC2 mutants are severely compromised. Thus, YidC2 may enable loss of the SRP by playing an independent but overlapping role in cotranslational protein insertion into the membrane. This is reminiscent of the situation in mitochondria that lack an SRP pathway and where Oxa1 facilitates cotranslational membrane protein insertion by binding directly to translation-active ribosomes. Here, we show that OXA1 complements a lack of yidC2 in S. mutans. YidC2 also functions reciprocally in oxa1-deficient Saccharomyces cerevisiae mutants and mediates the cotranslational insertion of mitochondrial translation products into the inner membrane. YidC2, like Oxa1, contains a positively charged C-terminal extension and associates with translating ribosomes. Our results are consistent with a gene-duplication event in gram-positive bacteria that enabled the specialization of a YidC isoform that mediates cotranslational activity independent of an SRP pathway.
Assuntos
Proteínas de Bactérias/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Duplicação Gênica , Proteínas Mitocondriais/genética , Proteínas Nucleares/genética , Biossíntese de Proteínas , Saccharomyces cerevisiae/genética , Streptococcus mutans/genética , Teste de Complementação Genética , Mitocôndrias/metabolismo , Modelos Genéticos , Mutação/genética , Filogenia , Ligação Proteica , Ribossomos/metabolismo , Saccharomyces cerevisiae/citologia , Fatores de TempoRESUMO
Members of the YidC/Oxa1/Alb3 protein family facilitate the insertion, folding and assembly of proteins of the inner membranes of bacteria and mitochondria and the thylakoid membrane of plastids. All homologs share a conserved hydrophobic core region comprising five transmembrane domains. On the basis of phylogenetic analyses, six subgroups of the family can be distinguished which presumably arose from three independent gene duplications followed by functional specialization. During evolution of bacteria, mitochondria and chloroplasts, subgroup-specific regions were added to the core domain to facilitate the association with ribosomes or other components contributing to the substrate spectrum of YidC/Oxa1/Alb3 proteins.
Assuntos
Bactérias , Cloroplastos , Evolução Molecular , Duplicação Gênica , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias , Bactérias/enzimologia , Bactérias/genética , Cloroplastos/enzimologia , Cloroplastos/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Mitocôndrias/enzimologia , Mitocôndrias/genética , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Filogenia , Dobramento de ProteínaRESUMO
We studied an Andean endemic group of species of the lichen-forming fungal genus Umbilicaria from the subalpine and low-alpine zone, with their biogeographic center in Bolivia and Peru. A number of species and varieties have been described from this element, but apparent instability in several morphological traits has made it difficult to precisely delimit taxa. Based on DNA sequences of nuclear ITS, LSU and mitochondrial SSU from extensive collections from Argentina, Bolivia, Chile, Colombia, Ecuador and Peru, we present here a molecular phylogenetic analysis of this Andean endemic element within genus Umbilicaria. All analyses (MP, ML and Bayesian) support a single origin for the element and a division into two major groups characterized by different apothecium types: the Umbilicaria dichroa group and U. calvescens group. Taxa U. krempelhuberi, U. peruviana and U. subcalvescens are nested withinn U. calvescens and are treated as conspecific with the latter species. The endemic element shares a most recent common ancestor with the Umbilicaria vellea group, which has a worldwide distribution and contains several asexually reproducing (sorediate) species. Independent reversals to sexual reproduction might explain the evolution of two types of apothecia in this monophyletic endemic lineage. A number of cosmopolitan, mostly high-alpine, species of Umbilicaria also present in the central Andes are related only remotely to the endemic element and do not exhibit speciation into endemics. Because the An-dean element dominates the Umbilicaria habitats of the low- and subalpine zones we propose that the founder colonized the Andes at a time when the mountains had not yet reached their current elevation while the high-alpine species arrived more recently.
Assuntos
Evolução Molecular , Líquens/genética , Sequência de Bases , Bolívia , DNA Fúngico/química , DNA Fúngico/genética , DNA Mitocondrial/química , DNA Mitocondrial/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Variação Genética , Líquens/classificação , Líquens/ultraestrutura , Dados de Sequência Molecular , Peru , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 5,8S/química , RNA Ribossômico 5,8S/genética , Alinhamento de SequênciaRESUMO
The genus Lecidea Ach. sensu lato (sensu Zahlbruckner) includes almost 1200 species, out of which only 100 species represent Lecidea sensu stricto (sensu Hertel). The systematic position of the remaining species is mostly unsettled but anticipated to represent several unrelated lineages within Lecanoromycetes. This study attempts to elucidate the phylogenetic placement of members of this heterogeneous group of lichen-forming fungi and to improve the classification and phylogeny of Lecanoromycetes. Twenty-five taxa of Lecidea sensu lato and 22 putatively allied species were studied in a broad selection of 268 taxa, representing 48 families of Lecanoromycetes. Six loci, including four ribosomal and two protein-coding genes for 315- and 209-OTU datasets were subjected to maximum likelihood and Bayesian analyses. The resulting well supported phylogenetic relationships within Lecanoromycetes are in agreement with published phylogenies, but the addition of new taxa revealed putative rearrangements of several families (e.g. Catillariaceae, Lecanoraceae, Lecideaceae, Megalariaceae, Pilocarpaceae and Ramalinaceae). As expected, species of Lecidea sensu lato and putatively related taxa are scattered within Lecanoromycetidae and beyond, with several species nested in Lecanoraceae and Pilocarpaceae and others placed outside currently recognized families in Lecanorales and orders in Lecanoromycetidae. The phylogenetic affiliations of Schaereria and Strangospora are outside Lecanoromycetidae, probably with Ostropomycetidae. All species referred to as Lecidea sensu stricto based on morphology (including the type species, Lecidea fuscoatra [L.] Ach.) form, with Porpidia species, a monophyletic group with high posterior probability outside Lecanorales, Peltigerales and Teloschistales, in Lecanoromycetidae, supporting the recognition of order Lecideales Vain. in this subclass. The genus name Lecidea must be redefined to apply only to Lecidea sensu stricto and to include at least some members of the genus Porpidia. Based on morphological and chemical similarities, as well as the phylogenetic relationship of Lecidea pullata sister to Frutidella caesioatra, the new combination Frutidella pullata is proposed here.
Assuntos
Ascomicetos/classificação , Ascomicetos/genética , Líquens , Sequência de Bases , DNA Fúngico/análise , DNA Fúngico/genética , DNA Mitocondrial/genética , DNA Ribossômico/análise , DNA Ribossômico/genética , DNA Espaçador Ribossômico/genética , Filogenia , RNA Polimerase II , RNA Ribossômico 5,8S , Subunidades Ribossômicas Maiores/genética , Subunidades Ribossômicas Menores/genética , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
The intermembrane space of mitochondria and the thylakoid lumen of chloroplasts are evolutionary descendents of the periplasmic space of bacteria. Presumably due to their common ancestry, the active oxidation of cysteinyl thiols is used in these three compartments in order to stabilize protein folding or to regulate protein function. In contrast, compartments of the eukaryotic cell which developed from the bacterial cytosol maintain cysteine residues largely reduced. Whereas the oxidizing machinery of bacteria is well characterized, that of mitochondria was only recently discovered and that of thylakoids still awaits to be identified. In mitochondria, protein oxidation is mediated by the sulfhydryl oxidase Erv1 which is highly conserved among eukaryotes. Erv1 oxidizes its substrate protein Mia40 which serves as an import receptor for proteins destined for the intermembrane space. This review summarizes the current knowledge on the mitochondrial disulfide relay system and compares its features to those of the periplasm and the thylakoid lumen. Although the sulfhydryl oxidases in the intermembrane space, Erv1, and the bacterial periplasm, DsbA-DsbB, share key structural features their primary sequence is not related and the evolutionary origin of Erv1 is unclear. On the basis of phylogenetic analyses of Erv1 sequences we propose that the mitochondrial oxidation machinery originated from a lateral gene transfer from flavobacteria-like prokaryotes early in eukaryotic evolution.
Assuntos
Proteínas de Bactérias/metabolismo , Cloroplastos/metabolismo , Proteínas de Escherichia coli/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Oxirredutases/metabolismo , Isomerases de Dissulfetos de Proteínas/metabolismo , Compostos de Sulfidrila/metabolismo , Proteínas de Bactérias/química , Proteínas de Escherichia coli/química , Proteínas de Membrana/química , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Oxirredução , Oxirredutases/química , Periplasma/metabolismo , Isomerases de Dissulfetos de Proteínas/química , Tilacoides/metabolismoRESUMO
SUMMARY: The Biopython project is a mature open source international collaboration of volunteer developers, providing Python libraries for a wide range of bioinformatics problems. Biopython includes modules for reading and writing different sequence file formats and multiple sequence alignments, dealing with 3D macro molecular structures, interacting with common tools such as BLAST, ClustalW and EMBOSS, accessing key online databases, as well as providing numerical methods for statistical learning. AVAILABILITY: Biopython is freely available, with documentation and source code at (www.biopython.org) under the Biopython license.
Assuntos
Biologia Computacional/métodos , Software , Bases de Dados Factuais , Internet , Linguagens de ProgramaçãoRESUMO
Fungi associated with photosynthetic organisms are major determinants of terrestrial biomass, nutrient cycling, and ecosystem productivity from the poles to the equator. Whereas most fungi are known because of their fruit bodies (e.g., saprotrophs), symptoms (e.g., pathogens), or emergent properties as symbionts (e.g., lichens), the majority of fungal diversity is thought to occur among species that rarely manifest their presence with visual cues on their substrate (e.g., the apparently hyperdiverse fungal endophytes associated with foliage of plants). Fungal endophytes are ubiquitous among all lineages of land plants and live within overtly healthy tissues without causing disease, but the evolutionary origins of these highly diverse symbionts have not been explored. Here, we show that a key to understanding both the evolution of endophytism and the diversification of the most species-rich phylum of Fungi (Ascomycota) lies in endophyte-like fungi that can be isolated from the interior of apparently healthy lichens. These "endolichenic" fungi are distinct from lichen mycobionts or any other previously recognized fungal associates of lichens, represent the same major lineages of Ascomycota as do endophytes, largely parallel the high diversity of endophytes from the arctic to the tropics, and preferentially associate with green algal photobionts in lichen thalli. Using phylogenetic analyses that incorporate these newly recovered fungi and ancestral state reconstructions that take into account phylogenetic uncertainty, we show that endolichenism is an incubator for the evolution of endophytism. In turn, endophytism is evolutionarily transient, with endophytic lineages frequently transitioning to and from pathogenicity. Although symbiotrophic lineages frequently give rise to free-living saprotrophs, reversions to symbiosis are rare. Together, these results provide the basis for estimating trophic transition networks in the Ascomycota and provide a first set of hypotheses regarding the evolution of symbiotrophy and saprotrophy in the most species-rich fungal phylum. [Ancestral state reconstruction; Ascomycota; Bayesian analysis; endolichenic fungi; fungal endophytes; lichens; pathogens; phylogeny; saprotrophy; symbiotrophy; trophic transition network.].
Assuntos
Ascomicetos , Evolução Biológica , Líquens/microbiologia , Plantas/microbiologia , SimbioseRESUMO
We present a 6-gene, 420-species maximum-likelihood phylogeny of Ascomycota, the largest phylum of Fungi. This analysis is the most taxonomically complete to date with species sampled from all 15 currently circumscribed classes. A number of superclass-level nodes that have previously evaded resolution and were unnamed in classifications of the Fungi are resolved for the first time. Based on the 6-gene phylogeny we conducted a phylogenetic informativeness analysis of all 6 genes and a series of ancestral character state reconstructions that focused on morphology of sporocarps, ascus dehiscence, and evolution of nutritional modes and ecologies. A gene-by-gene assessment of phylogenetic informativeness yielded higher levels of informativeness for protein genes (RPB1, RPB2, and TEF1) as compared with the ribosomal genes, which have been the standard bearer in fungal systematics. Our reconstruction of sporocarp characters is consistent with 2 origins for multicellular sexual reproductive structures in Ascomycota, once in the common ancestor of Pezizomycotina and once in the common ancestor of Neolectomycetes. This first report of dual origins of ascomycete sporocarps highlights the complicated nature of assessing homology of morphological traits across Fungi. Furthermore, ancestral reconstruction supports an open sporocarp with an exposed hymenium (apothecium) as the primitive morphology for Pezizomycotina with multiple derivations of the partially (perithecia) or completely enclosed (cleistothecia) sporocarps. Ascus dehiscence is most informative at the class level within Pezizomycotina with most superclass nodes reconstructed equivocally. Character-state reconstructions support a terrestrial, saprobic ecology as ancestral. In contrast to previous studies, these analyses support multiple origins of lichenization events with the loss of lichenization as less frequent and limited to terminal, closely related species.
Assuntos
Ascomicetos/genética , Filogenia , Ascomicetos/classificação , Ascomicetos/citologia , Ecossistema , Genes Fúngicos , ReproduçãoRESUMO
The class Eurotiomycetes (Ascomycota, Pezizomycotina) is a monophyletic group comprising two major clades of very different ascomycetous fungi: (i) the subclass Eurotiomycetidae, a clade that contains most of the fungi previously recognized as Plectomycetes because of their mostly enclosed ascomata and prototunicate asci; and (ii) the subclass Chaetothyriomycetidae, a group of fungi that produce ascomata with an opening reminiscent of those produced by Dothideomycetes or Sordariomycetes. In this paper we use phylogenetic analyses based on data available from the Assembling the Fungal Tree of Life project (AFTOL), in addition to sequences in GenBank, to outline this important group of fungi. The Eurotiomycetidae include producers of toxic and useful secondary metabolites, fermentation agents used to make food products and enzymes, xerophiles and psychrophiles, and the important genetics model Aspergillus nidulans. The Chaetothyriomycetidae include the common black yeast fungi, some of which are pathogens of humans and animals, as well as some primarily lichenized groups newly found to be phylogenetically associated with this group. The recently proposed order Mycocaliciales shows a sister relationship with Eurotiomycetes. The great majority of human pathogenic Pezizomycotina are Eurotiomycetes, particularly in Eurotiales, Onygenales and Chaetothyriales. Due to their broad importance in basic research, industry and public health, several genome projects have focused on species in Onygenales and Eurotiales.
Assuntos
Ascomicetos/classificação , Ascomicetos/genética , Filogenia , Ascomicetos/citologia , Análise por Conglomerados , DNA Fúngico/genética , DNA Ribossômico/genética , Ecologia , Dados de Sequência Molecular , Fator 1 de Elongação de Peptídeos/genética , RNA Polimerase II/genética , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Análise de Sequência de DNA , Homologia de SequênciaRESUMO
The Lecanoromycetes includes most of the lichen-forming fungal species (> 13500) and is therefore one of the most diverse class of all Fungi in terms of phenotypic complexity. We report phylogenetic relationships within the Lecanoromycetes resulting from Bayesian and maximum likelihood analyses with complementary posterior probabilities and bootstrap support values based on three combined multilocus datasets using a supermatrix approach. Nine of 10 orders and 43 of 64 families currently recognized in Eriksson's classification of the Lecanoromycetes (Outline of Ascomycota--2006 Myconet 12:1-82) were represented in this sampling. Our analyses strongly support the Acarosporomycetidae and Ostropomycetidae as monophyletic, whereas the delimitation of the largest subclass, the Lecanoromycetidae, remains uncertain. Independent of future delimitation of the Lecanoromycetidae, the Rhizocarpaceae and Umbilicariaceae should be elevated to the ordinal level. This study shows that recent classifications include several nonmonophyletic taxa at different ranks that need to be recircumscribed. Our phylogenies confirm that ascus morphology cannot be applied consistently to shape the classification of lichen-forming fungi. The increasing amount of missing data associated with the progressive addition of taxa resulted in some cases in the expected loss of support, but we also observed an improvement in statistical support for many internodes. We conclude that a phylogenetic synthesis for a chosen taxonomic group should include a comprehensive assessment of phylogenetic confidence based on multiple estimates using different methods and on a progressive taxon sampling with an increasing number of taxa, even if it involves an increasing amount of missing data.
Assuntos
Ascomicetos/classificação , Ascomicetos/genética , Evolução Molecular , Filogenia , Análise por Conglomerados , Biologia Computacional , DNA Fúngico/genética , DNA Mitocondrial/genética , DNA Ribossômico/genética , RNA Polimerase II/genética , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Homologia de SequênciaRESUMO
Parmelioid lichens form a species-rich group of predominantly foliose and fruticose lichenized fungi encompassing a broad range of morphological and chemical diversity. Using a multilocus approach, we reconstructed a phylogeny including 323 OTUs of parmelioid lichens and employed ancestral character reconstruction methods to understand the phenotypical evolution within this speciose group of lichen-forming fungi. Specifically, we were interested in the evolution of growth form, epicortex structure, and cortical chemistry. Since previous studies have shown that results may differ depending on the reconstruction method used, here we employed both maximum-parsimony and maximum-likelihood approaches to reconstruct ancestral character states. We have also implemented binary and multistate coding of characters and performed parallel analyses with both coding types to assess for potential coding-based biases. We reconstructed the ancestral states for nine well-supported major clades in the parmelioid group, two higher-level sister groups and the ancestral character state for all parmelioid lichens. We found that different methods for coding phenotypical characters and different ancestral character state reconstruction methods mostly resulted in identical reconstructions but yield conflicting inferences of ancestral states, in some cases. However, we found support for the ancestor of parmelioid lichens having been a foliose lichen with a non-pored epicortex and pseudocyphellae. Our data suggest that some traits exhibit patterns of evolution consistent with adaptive radiation.