September 22, 2019  |  

Multi-platform assessment of transcriptome profiling using RNA-seq in the ABRF next-generation sequencing study.

High-throughput RNA sequencing (RNA-seq) greatly expands the potential for genomics discoveries, but the wide variety of platforms, protocols and performance capabilitites has created the need for comprehensive reference data. Here we describe the Association of Biomolecular Resource Facilities next-generation sequencing (ABRF-NGS) study on RNA-seq. We carried out replicate experiments across 15 laboratory sites using reference RNA standards to test four protocols (poly-A-selected, ribo-depleted, size-selected and degraded) on five sequencing platforms (Illumina HiSeq, Life Technologies PGM and Proton, Pacific Biosciences RS and Roche 454). The results show high intraplatform (Spearman rank R > 0.86) and inter-platform (R > 0.83) concordance for expression measures across the deep-count platforms, but highly variable efficiency and cost for splice junction and variant detection between all platforms. For intact RNA, gene expression profiles from rRNA-depletion and poly-A enrichment are similar. In addition, rRNA depletion enables effective analysis of degraded RNA samples. This study provides a broad foundation for cross-platform standardization, evaluation and improvement of RNA-seq.

July 7, 2019  |  

Complete genome sequence of an Edwardsiella piscicida-like species isolated from diseased grouper in Israel.

The Edwardsiella piscicida-like sp. is a Gram-negative facultative anaerobe that causes disease in some fish species. We report here the complete genome sequence of a virulent isolate from a diseased white grouper (Epinephelus aeneus) raised on the Red Sea in Israel, which contains a chromosome of 3,934,167 bp and no plasmids. Copyright © 2015 Reichley et al.

July 7, 2019  |  

Comparative genomics reveals insights into avian genome evolution and adaptation.

Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits. Copyright © 2014, American Association for the Advancement of Science.

July 7, 2019  |  

Complex modular architecture around a simple toolkit of wing pattern genes

Identifying the genomic changes that control morphological variation and understanding how they generate diversity is a major goal of evolutionary biology. In Heliconius butterflies, a small number of genes control the development of diverse wing colour patterns. Here, we used full-genome sequencing of individuals across the Heliconius erato radiation and closely related species to characterize genomic variation associated with wing pattern diversity. We show that variation around colour pattern genes is highly modular, with narrow genomic intervals associated with specific differences in colour and pattern. This modular architecture explains the diversity of colour patterns and provides a flexible mechanism for rapid morphological diversification.

July 7, 2019  |  

Complete genome sequence of Edwardsiella hoshinae ATCC 35051.

Edwardsiella hoshinae is a Gram-negative facultative anaerobe that has primarily been isolated from avians and reptiles. We report here the complete and annotated genome sequence of an isolate from a monitor lizard (Varanus sp.), which contains a chromosome of 3,811,650 bp and no plasmids. Copyright © 2017 Reichley et al.

July 7, 2019  |  

Genomics-enabled analysis of the emergent disease cotton bacterial blight.

Cotton bacterial blight (CBB), an important disease of (Gossypium hirsutum) in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm) strains. Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal important insights into the Xcm-G. hirsutum disease complex and strategies for future development of resistant cultivars.

July 7, 2019  |  

The genome of the cotton bacterial blight pathogen Xanthomonas citri pv. malvacearum strain MSCT1.

Xanthomonas citri pv. malvacearum is a major pathogen of cotton, Gossypium hirsutum L.. In this study we report the complete genome of the X. citri pv. malvacearum strain MSCT1 assembled from long read DNA sequencing technology. The MSCT1 genome is the first X. citri pv. malvacearum genome with complete coding regions for X. citri pv. malvacearum transcriptional activator-like effectors. In addition functional and structural annotations are presented in this study that will provide a foundation for future pathogenesis studies with MSCT1.

July 7, 2019  |  

Whole genome sequence of two Rathayibacter toxicus strains reveals a tunicamycin biosynthetic cluster similar to Streptomyces chartreusis.

Rathayibacter toxicus is a forage grass associated Gram-positive bacterium of major concern to food safety and agriculture. This species is listed by USDA-APHIS as a plant pathogen select agent because it produces a tunicamycin-like toxin that is lethal to livestock and may be vectored by nematode species native to the U.S. The complete genomes of two strains of R. toxicus, including the type strain FH-79, were sequenced and analyzed in comparison with all available, complete R. toxicus genomes. Genome sizes ranged from 2,343,780 to 2,394,755 nucleotides, with 2079 to 2137 predicted open reading frames; all four strains showed remarkable synteny over nearly the entire genome, with only a small transposed region. A cluster of genes with similarity to the tunicamycin biosynthetic cluster from Streptomyces chartreusis was identified. The tunicamycin gene cluster (TGC) in R. toxicus contained 14 genes in two transcriptional units, with all of the functional elements for tunicamycin biosynthesis present. The TGC had a significantly lower GC content (52%) than the rest of the genome (61.5%), suggesting that the TGC may have originated from a horizontal transfer event. Further analysis indicated numerous remnants of other potential horizontal transfer events are present in the genome. In addition to the TGC, genes potentially associated with carotenoid and exopolysaccharide production, bacteriocins and secondary metabolites were identified. A CRISPR array is evident. There were relatively few plant-associated cell-wall hydrolyzing enzymes, but there were numerous secreted serine proteases that share sequence homology to the pathogenicity-associated protein Pat-1 of Clavibacter michiganensis. Overall, the genome provides clear insight into the possible mechanisms for toxin production in R. toxicus, providing a basis for future genetic approaches.

July 7, 2019  |  

Complete genome sequence of Edwardsiella piscicida isolate S11-285 recovered from channel catfish (Ictalurus punctatus) in Mississippi, USA.

Edwardsiella piscicida is a recently described Gram-negative facultative anaerobe and an important pathogen to many wild and cultured fish species worldwide. Here, we report the complete and annotated genome of E. piscicida isolate S11-285 recovered from channel catfish (Ictalurus punctatus), consisting of a chromosome of 3,923,603 bp and 1 plasmid. Copyright © 2016 Reichley et al.

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