Glycopeptide antibiotics are produced by Actinobacteria through biosynthetic gene clusters that include genes supporting their regulation, synthesis, export and resistance. The chemical and biosynthetic diversities of glycopeptides are the product of an intricate evolutionary history. Extracting this history from genome sequences is difficult as conservation of the individual components of these gene clusters is variable and each component can have a different trajectory. We show that glycopeptide biosynthesis and resistance in Actinobacteria maps to approximately 150-400 million years ago. Phylogenetic reconciliation reveals that the precursors of glycopeptide biosynthesis are far older than other components, implying that these clusters arose from…
DNA transformation and homology-based transcriptional silencing are frequently used to assess gene function in Phytophthora. Since unplanned side-effects of these tools are not well-characterized, we used P. infestans to study plasmid integration sites and whether knockdowns caused by homology-dependent silencing spreads to other genes. Insertions occurred both in gene-dense and gene-sparse regions but disproportionately near the 5′ ends of genes, which disrupted native coding sequences. Microhomology at the recombination site between plasmid and chromosome was common. Studies of transformants silenced for twelve different gene targets indicated that neighbors within 500-nt were often co-silenced, regardless of whether hairpin or sense constructs…
Background New sequencing technologies have lowered financial barriers to whole genome sequencing, but resulting assemblies are often fragmented and far from textquoteleftfinishedtextquoteright. Updating multi-scaffold drafts to chromosome-level status can be achieved through experimental mapping or re-sequencing efforts. Avoiding the costs associated with such approaches, comparative genomic analysis of gene order conservation (synteny) to predict scaffold neighbours (adjacencies) offers a potentially useful complementary method for improving draft assemblies.Results We employed three gene synteny-based methods applied to 21 Anopheles mosquito assemblies to produce consensus sets of scaffold adjacencies. For subsets of the assemblies we integrated these with additional supporting data to confirm…
Recent studies suggest that closely related species can accumulate substantial genetic and phenotypic differences despite ongoing gene flow, thus challenging traditional ideas regarding the genetics of speciation. Baboons (genus Papio) are Old World monkeys consisting of six readily distinguishable species. Baboon species hybridize in the wild, and prior data imply a complex history of differentiation and introgression. We produced a reference genome assembly for the olive baboon (Papio anubis) and whole-genome sequence data for all six extant species. We document multiple episodes of admixture and introgression during the radiation of Papio baboons, thus demonstrating their value as a model of…
Candidatus Thioglobus sp.textquotedblright strain NP1 is an open-ocean isolate from the SUP05 clade of Gammaproteobacteria. Whole-genome comparisons of strain NP1 to other sequenced isolates from the SUP05 clade indicate that it represents a new species of SUP05 that lacks the ability to fix inorganic carbon using the Calvin-Benson-Bassham cycle.
Long reads obtained from third-generation sequencing platforms can help overcome the long-standing challenge of the de novo assembly of sequences for the genomic analysis of non-model eukaryotic organisms. Numerous long-read-aided de novo assemblies have been published recently, which exhibited superior quality of the assembled genomes in comparison with those achieved using earlier second-generation sequencing technologies. Evaluating assemblies is important in guiding the appropriate choice for specific research needs. In this study, we evaluated 10 long-read assemblers using a variety of metrics on Pacific Biosciences (PacBio) data sets from different taxonomic categories with considerable differences in genome size. The results allowed…
A novel facultative anaerobic and Gram-stain-positive coccus, designated strain ChDC F135T, was isolated from human subgingival dental plaque of periodontitis lesion and was characterized by polyphasic taxonomic analysis. The 16S rRNA gene (16S rDNA) sequence of strain ChDC F135T was closest to that of Streptococcus sinensis HKU4T (98.2%), followed by Streptococcus intermedia SK54T (97.0%), Streptococcus constellatus NCTC11325T (96.0%), and Streptococcus anginosus NCTC 10713T (95.7%). In contrast, phylogenetic analysis based on the superoxide dismutase gene (sodA) and the RNA polymerase beta-subunit gene (rpoB) showed that the nucleotide sequence similarities of strain ChDC F135T were highly similar to the corresponding genes of…
The commercial release of third-generation sequencing technologies (TGSTs), giving long and ultra-long sequencing reads, has stimulated the development of new tools for assembling highly contiguous genome sequences with unprecedented accuracy across complex repeat regions. We survey here a wide range of emerging sequencing platforms and analytical tools for de novo assembly, provide background information for each of their steps, and discuss the spectrum of available options. Our decision tree recommends workflows for the generation of a high-quality genome assembly when used in combination with the specific needs and resources of a project.Copyright © 2019 Elsevier Ltd. All rights reserved.
Within the economically important plant family Solanaceae, Jaltomata is a rapidly evolving genus that has extensive diversity in flower size and shape, as well as fruit and nectar color, among its ~80 species. Here, we report the whole-genome sequencing, assembly, and annotation, of one representative species (Jaltomata sinuosa) from this genus. Combining PacBio long reads (25×) and Illumina short reads (148×) achieved an assembly of ~1.45?Gb, spanning ~96% of the estimated genome. Ninety-six percent of curated single-copy orthologs in plants were detected in the assembly, supporting a high level of completeness of the genome. Similar to other Solanaceous species, repetitive…
Heterochromatic regions of the genome are repeat-rich and poor in protein coding genes, and are therefore underrepresented in even the best genome assemblies. One of the most difficult regions of the genome to assemble are sex-limited chromosomes. The Drosophila melanogaster Y chromosome is entirely heterochromatic, yet has wide-ranging effects on male fertility, fitness, and genome-wide gene expression. The genetic basis of this phenotypic variation is difficult to study, in part because we do not know the detailed organization of the Y chromosome. To study Y chromosome organization in D. melanogaster, we develop an assembly strategy involving the in silico enrichment…
Two Gram-stain-positive, small ellipsoidal cocci, non-motile, oxidase- and catalase-negative, and facultative anaerobic strains (UCMA15228T and UCMA17102) were isolated in France, from fermented apple juices (ciders). The 16S rRNA gene sequence was identical between the two isolates and showed 97 % similarity with respect to the closest related species Oenococcus oeni and O. kitaharae. Therefore, the two isolates were classified within the genus Oenococcus. The phylogeny based on the pheS gene sequences also confirmed the position of the new taxon. DNA-DNA hybridizations based on in silico genome-to-genome comparisons (GGDC) and Average Nucleotide Identity (ANI) values, as well as species-specific PCR, validated…
Three mesophilic, Gram-stain-positive, aerobic bacterial strains, designated Uno3T, Uno11T and Uno16T, were isolated from a soil-like granular micro-organism mass (termed Tengu-no-mugimeshi) collected from Tsumagoi, Gunma, Japan. They grow at 11-37?°C?and pH 4.0-8.0, form branched mycelia, and have a G+C?content between 49.4-50.3?mol%. The major menaquinone and fatty acid of Uno3T are MK-9 and iso-C16?:?0, respectively, whereas Uno11T and Uno16T share MK-9 (H2) and C16?:?1-2OH. The major cell-wall sugars are mannose (Uno3T and Uno11T) and glucose (Uno16T). Phylogenetic analysis based on 16S rRNA gene sequences indicated that these three strains belong to the order Ktedonobacterales and are most closely related to Dictyobacter…
Genome evolution and development of unicellular, multinucleate macroalgae (siphonous algae) are poorly known, although various multicellular organisms have been studied extensively. To understand macroalgal developmental evolution, we assembled the ~26?Mb genome of a siphonous green alga, Caulerpa lentillifera, with high contiguity, containing 9,311 protein-coding genes. Molecular phylogeny using 107 nuclear genes indicates that the diversification of the class Ulvophyceae, including C. lentillifera, occurred before the split of the Chlorophyceae and Trebouxiophyceae. Compared with other green algae, the TALE superclass of homeobox genes, which expanded in land plants, shows a series of lineage-specific duplications in this siphonous macroalga. Plant hormone signalling…
Birds are a group with immense availability of genomic resources, and hundreds of forthcoming genomes at the doorstep. We review recent developments in whole genome sequencing, phylogenomics, and comparative genomics of birds. Short read based genome assemblies are common, largely due to efforts of the Bird 10K genome project (B10K). Chromosome-level assemblies are expected to increase due to improved long-read sequencing. The available genomic data has enabled the reconstruction of the bird tree of life with increasing confidence and resolution, but challenges remain in the early splits of Neoaves due to their explosive diversification after the Cretaceous-Paleogene (K-Pg) event. Continued…
Reference quality de novo genome assemblies were once solely the domain of large, well-funded genome projects. While next-generation short read technology removed some of the cost barriers, accurate chromosome-scale assembly remains a real challenge. Here we present efforts to de novo assemble the goat (Capra hircus) genome. Through the combination of single-molecule technologies from Pacific Biosciences (sequencing) and BioNano Genomics (optical mapping) coupled with high-throughput chromosome conformation capture sequencing (Hi-C), an inbred San Clemente goat genome has been sequenced and assembled to a high degree of completeness at a relatively modest cost. Starting with 38 million PacBio reads, we integrated…