Although engineered nucleases can efficiently cleave intracellular DNA at desired target sites, major concerns remain on potential ‘off-target’ cleavage that may occur throughout the genome. We developed an online tool: predicted report of genome-wide nuclease off-target sites (PROGNOS) that effectively identifies off-target sites. The initial bioinformatics algorithms in PROGNOS were validated by predicting 44 of 65 previously confirmed off-target sites, and by uncovering a new off-target site for the extensively studied zinc finger nucleases (ZFNs) targeting C-C chemokine receptor type 5. Using PROGNOS, we rapidly interrogated 128 potential off-target sites for newly designed transcription activator-like effector nucleases containing either Asn-Asn…
Traditionally derived from fossil fuels, biological production of propionic acid has recently gained interest. Propionibacterium species produce propionic acid as their main fermentation product. Production of other organic acids reduces propionic acid yield and productivity, pointing to by-products gene-knockout strategies as a logical solution to increase yield. However, removing by-product formation has seen limited success due to our inability to genetically engineer the best producing strains (i.e. Propionibacterium acidipropionici). To overcome this limitation, random mutagenesis continues to be the best path towards improving strains for biological propionic acid production. Recent advances in next generation sequencing opened new avenues to understand…
The possibility to predict the outcome of targeted DNA double-stranded break (DSB) repair would be desirable for genome editing. Furthermore the consequences of mis-repair of potentially cell-lethal DSBs and the underlying pathways are not yet fully understood. Here we study the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-induced mutation spectra at three selected endogenous loci in Arabidopsis thaliana by deep sequencing of long amplicon libraries. Notably, we found sequence-dependent genomic features that affected the DNA repair outcome. Deletions of 1-bp to 1 kbp (all due to NHEJ) and deletions combined with insertions between 5-bp to >100 bp [caused by a synthesis-dependent strand…
Existing recombinant adeno-associated virus (rAAV) serotypes for delivering in vivo gene therapy treatments for human liver diseases have not yielded combined high-level human hepatocyte transduction and favorable humoral neutralization properties in diverse patient groups. Yet, these combined properties are important for therapeutic efficacy. To bioengineer capsids that exhibit both unique seroreactivity profiles and functionally transduce human hepatocytes at therapeutically relevant levels, we performed multiplexed sequential directed evolution screens using diverse capsid libraries in both primary human hepatocytes in vivo and with pooled human sera from thousands of patients. AAV libraries were subjected to five rounds of in vivo selection in xenografted mice with…
We report a genome-editing strategy to correct compound heterozygous mutations, a common genotype in patients with recessive genetic disorders. Adeno-associated viral vector delivery of Cas9 and guide RNA induces allelic exchange and rescues the disease phenotype in mouse models of hereditary tyrosinemia type I and mucopolysaccharidosis type I. This approach recombines non-mutated genetic information present in two heterozygous alleles into one functional allele without using donor DNA templates.
The yellow catfish, Pelteobagrus fulvidraco, belonging to the Siluriformes order, is an economically important freshwater aquaculture fish species in Asia, especially in Southern China. The aquaculture industry has recently been facing tremendous challenges in germplasm degeneration and poor disease resistance. As the yellow catfish exhibits notable sex dimorphism in growth, with adult males about two- to three-fold bigger than females, the way in which the aquaculture industry takes advantage of such sex dimorphism is another challenge. To address these issues, a high-quality reference genome of the yellow catfish would be a very useful resource.To construct a high-quality reference genome for…
Cereal grasses of the Triticeae tribe have been the major food source in temperate regions since the dawn of agriculture. Their large genomes are characterized by a high content of repetitive elements and large pericentromeric regions that are virtually devoid of meiotic recombination. Here we present a high-quality reference genome assembly for barley (Hordeum vulgare L.). We use chromosome conformation capture mapping to derive the linear order of sequences across the pericentromeric space and to investigate the spatial organization of chromatin in the nucleus at megabase resolution. The composition of genes and repetitive elements differs between distal and proximal regions.…
Autism spectrum disorder (ASD) is one of the most heritable neuropsychiatric conditions. The complex genetic landscape of the disorder includes both common and rare variants at hundreds of genetic loci. This marked heterogeneity has thus far hampered efforts to develop genetic diagnostic panels and targeted pharmacological therapies. Here, we give an overview of the current literature on the genetic basis of ASD, and review recent human brain transcriptome studies and their role in identifying convergent pathways downstream of the heterogeneous genetic variants. We also discuss emerging evidence on the involvement of non-coding genomic regions and non-coding RNAs in ASD.
Accurate transcript structure and abundance inference from RNA sequencing (RNA-seq) data is foundational for molecular discovery. Here we present TACO, a computational method to reconstruct a consensus transcriptome from multiple RNA-seq data sets. TACO employs novel change-point detection to demarcate transcript start and end sites, leading to improved reconstruction accuracy compared with other tools in its class. The tool is available at http://tacorna.github.io and can be readily incorporated into RNA-seq analysis workflows.
Human Embryonic Stem Cells (hESCs) are in vitro derivatives of the inner cell mass of the blastocyst and are characterized by an undifferentiated and pluripotent state that can be perpetuated in time, indefinitely. hESCs provide a unique opportunity to both dissect the molecular mechanisms that are predisposed to the maintenance of pluripotency and model the ability to initiate differentiation and cell commitment within the developing embryo. To fully understand these mechanisms, it is necessary to accurately identify the specific transcriptome of hESCs. Many distinct gene annotation methods, such as cDNA and EST sequencing and RNA-Seq, have been used to identify…
Second-generation, high-throughput sequencing methods have greatly improved our understanding of the ecology of soil microorganisms, yet the short barcodes ( 500-bp barcode for reliable identification or when phylogenetic approaches are intended.© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
The lungs of Cystic fibrosis (CF) patients are often colonized and/or infected by Staphylococcus aureus for years, mostly by one predominant clone. For long-term survival in this environment, S. aureus needs to adapt during its interactions with host factors, antibiotics, and other pathogens. Here, we study long-term transcriptional as well as genomic adaptations of an isogenic pair of S. aureus isolates from a single patient using RNA sequencing (RNA-Seq) and whole genome sequencing (WGS). Mimicking in vivo conditions, we cultivated the S. aureus isolates using artificial sputum medium before harvesting RNA for subsequent analysis. We confirmed our RNA-Seq data using…
Biogas reactors operating with protein-rich substrates have high methane potential and industrial value; however, they are highly susceptible to process failure because of the accumulation of ammonia. High ammonia levels cause a decline in acetate-utilizing methanogens and instead promote the conversion of acetate via a two-step mechanism involving syntrophic acetate oxidation (SAO) to H2 and CO2, followed by hydrogenotrophic methanogenesis. Despite the key role of syntrophic acetate-oxidizing bacteria (SAOB), only a few culturable representatives have been characterized. Here we show that the microbiome of a commercial, ammonia-tolerant biogas reactor harbors a deeply branched, uncultured phylotype (unFirm_1) accounting for approximately 5%…
The DOE-JGI Microbial Genome Annotation Pipeline performs structural and functional annotation of microbial genomes that are further included into the Integrated Microbial Genome comparative analysis system. MGAP is applied to assembled nucleotide sequence datasets that are provided via the IMG submission site. Dataset submission for annotation first requires project and associated metadata description in GOLD. The MGAP sequence data processing consists of feature prediction including identification of protein-coding genes, non-coding RNAs and regulatory RNA features, as well as CRISPR elements. Structural annotation is followed by assignment of protein product names and functions.
Transcript prediction can be modeled as a graph problem where exons are modeled as nodes and reads spanning two or more exons are modeled as exon chains. Pacific Biosciences third-generation sequencing technology produces significantly longer reads than earlier second-generation sequencing technologies, which gives valuable information about longer exon chains in a graph. However, with the high error rates of third-generation sequencing, aligning long reads correctly around the splice sites is a challenging task. Incorrect alignments lead to spurious nodes and arcs in the graph, which in turn lead to incorrect transcript predictions. We survey several approaches to find the exon…