T-BAS: Tree-Based Alignment Selector toolkit for phylogenetic-based placement, alignment downloads and metadata visualization: an example with the Pezizomycotina tree of life.

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.

Bendamustine plus rituximab versus fludarabine plus rituximab for patients with relapsed indolent and mantle-cell lymphomas: a multicentre, randomised, open-label, non-inferiority phase 3 trial.

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).

A multigene phylogenetic synthesis for the class Lecanoromycetes (Ascomycota): 1307 fungi representing 1139 infrageneric taxa, 317 genera and 66 families.

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.

A phylogenomics approach for selecting robust sets of phylogenetic markers.

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.

Placing environmental next-generation sequencing amplicons from microbial eukaryotes into a phylogenetic context.

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.

Genotypic and phenotypic diversity of cyanobacteria in biological soil crusts of the Succulent Karoo and Nama Karoo of southern Africa.

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.

Understanding phenotypical character evolution in parmelioid lichenized fungi (Parmeliaceae, Ascomycota).

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.

Protein import and oxidative folding in the mitochondrial intermembrane space of intact mammalian cells.

Oxidation of cysteine residues to disulfides drives import of many proteins into the intermembrane space of mitochondria. Recent studies in yeast unraveled the basic principles of mitochondrial protein oxidation, but the kinetics under physiological conditions is unknown. We developed assays to follow protein oxidation in living mammalian cells, which reveal that import and oxidative folding of proteins are kinetically and functionally coupled and depend on the oxidoreductase Mia40, the sulfhydryl oxidase augmenter of liver regeneration (ALR), and the intracellular glutathione pool. Kinetics of substrate oxidation depends on the amount of Mia40 and requires tightly balanced amounts of ALR. Mia40-dependent import of Cox19 in human cells depends on the inner membrane potential. Our observations reveal considerable differences in the velocities of mitochondrial import pathways: whereas preproteins with bipartite targeting sequences are imported within seconds, substrates of Mia40 remain in the cytosol for several minutes and apparently escape premature degradation and oxidation.

Gray mold populations in german strawberry fields are resistant to multiple fungicides and dominated by a novel clade closely related to Botrytis cinerea.

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.

Partial suppression of Oxa1 mutants by mitochondria-targeted signal recognition particle provides insights into the evolution of the cotranslational insertion systems.

The biogenesis of hydrophobic membrane proteins involves their cotranslational membrane integration in order to prevent their unproductive aggregation. In the cytosol of bacteria and eukaryotes, membrane targeting of ribosomes that synthesize membrane proteins is achieved by signal recognition particles (SRPs) and their cognate membrane-bound receptors. As is evident from the genomes of fully sequenced eukaryotes, mitochondria generally lack an SRP system. Instead, mitochondrial ribosomes are physically associated with the protein insertion machinery in the inner membrane. Accordingly, deletion of ribosome-binding sites on the Oxa1 insertase and the Mba1 ribosome receptor in yeast leads to severe defects in cotranslational protein insertion and results in respiration-deficient mutants. In this study, we expressed mitochondria-targeted versions of the bacterial SRP protein Ffh and its receptor FtsY in these yeast mutants. Interestingly, Ffh was found to bind to the large subunit of mitochondrial ribosomes, and could relieve, to some degree, the defect of these insertion mutants. Although FtsY could also bind to mitochondrial membranes, it did not improve membrane protein biogenesis in this strain, presumably because of its inability to interact with Ffh. Hence, mitochondrial ribosomes are still able to interact physically and functionally with the bacterial SRP system. Our observations are consistent with a model according to which the protein insertion system in mitochondria evolved in three steps. The loss of genes for hydrophilic polypeptides (step 1) allowed the development of ribosome-binding sites on membrane proteins (step 2), which finally made the existence of an SRP-mediated system dispensable (step 3).

Frequent circumarctic and rare transequatorial dispersals in the lichenised agaric genus Lichenomphalia (Hygrophoraceae, Basidiomycota).

Species of the genus Lichenomphalia are mostly restricted to arctic-alpine environments with the exception of Lichenomphalia umbellifera which is also common in northern forests. Although Lichenomphalia species inhabit vast regions in several continents, no information is available on their genetic variation across geographic regions and the underlying population-phylogenetic patterns. We collected samples from arctic and subarctic regions, as well as from newly discovered subantarctic localities for the genus. Phylogenetic, nonparametric permutation methods, and coalescent analyses were used to assess phylogeny and population divergence and to estimate the extent and direction of gene flow among distinct geographic populations. All known species formed monophyletic groups, supporting their morphology-based delimitation. In addition, we found two subantarctic phylogenetic species (Lichenomphalia sp. and Lichenomphalia aff. umbellifera), of which the latter formed a well-supported sister group to L. umbellifera. We found no significant genetic differentiation among conspecific North American and Eurasian populations in Lichenomphalia. We detected high intercontinental gene flow within the northern polar region, suggesting rapid (re)colonisation of suitable habitats in response to climatic fluctuations and preventing pronounced genetic differentiation. On the other hand, our phylogenetic analyses suggest that dispersal between northern circumpolar and subantarctic areas likely happened very rarely and led to the establishment and subsequent divergence of lineages. Due to limited sampling in the Southern Hemisphere, it is currently uncertain whether the northern lineages occur in Gondwanan regions. On the other hand, our results strongly suggest that the southern lineages do not occur in the circumpolar north. Although rare transequatorial dispersal and subsequent isolation may explain the emergence of at least two subantarctic phylogenetic species lineages in Lichenomphalia, more samples from the Southern Hemisphere are needed to better understand the phylogeographic history of the genus.

Molecular Diversity of Fungi from Marine Oxygen-Deficient Environments (ODEs).

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.

Phylogenetic affiliations of members of the heterogeneous lichen-forming fungi of the genus Lecidea sensu Zahlbruckner (Lecanoromycetes, Ascomycota).

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.

Evolution of YidC/Oxa1/Alb3 insertases: three independent gene duplications followed by functional specialization in bacteria, mitochondria and chloroplasts.

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.

Single origin and subsequent diversification of central Andean endemic Umbilicaria species.

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.

Systematic analysis of the twin cx(9)c protein family.

The Mia40-Erv1 disulfide relay system is of high importance for mitochondrial biogenesis. Most so far identified substrates of this machinery contain either two cysteine-x(3)-cysteine (twin Cx(3)C) or two cysteine-x(9)-cysteine (twin Cx(9)C) motifs. While the first group is composed of well-characterized components of the mitochondrial import machinery, the molecular function of twin Cx(9)C proteins still remains unclear. To systematically characterize this protein family, we performed a database search to identify the full complement of Cx(9)C proteins in yeast. Thereby, we identified 14 potential family members, which, with one exception, are conserved among plants, fungi, and animals. Among these, three represent novel proteins, which we named Cmc2 to 4 (for Cx(9)C motif-containing protein) and which we demonstrated to be dependent for import on the Mia40-Erv1 disulfide relay. By testing deletion mutants of all 14 proteins for function of the respiratory chain, we found a critical function of most of these proteins for the assembly or stability of respiratory chain complexes. Our data suggest that already early during the evolution of eukaryotic cells, a multitude of twin Cx(9)C proteins developed, which exhibit largely nonredundant roles critical for the biogenesis of enzymes of the respiratory chain in mitochondria.

Independent gene duplications of the YidC/Oxa/Alb3 family enabled a specialized cotranslational function.

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.

Biopython: freely available Python tools for computational molecular biology and bioinformatics.

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.

Thiol oxidation in bacteria, mitochondria and chloroplasts: common principles but three unrelated machineries?

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.

The Ascomycota tree of life: a phylum-wide phylogeny clarifies the origin and evolution of fundamental reproductive and ecological traits.

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.