Project description:Genome editing tools with high precision are key to develop improved crops but current technologies to place new DNA into specific locations in plant genomes are low frequency and error-prone. Transposable elements (TEs) evolved to insert their DNA seamlessly into genomes, albeit in a quasi-random pattern. We developed a genome engineering tool that controls the TE insertion site and subsequently the delivery of any cargo attached to this TE. Using our tool, we demonstrated sequence-specific targeted delivery (guided by the CRISPR gRNA) of enhancers, an open reading frame and gene expression cassette into the genome of the model plant Arabidopsis, and we translated this technology to the crop soybean. We have engineered a ‘junk’ TE into a useful and accessible toolkit that enables the sequence-specific targeting of custom DNA into plant genomes.
Project description:Genome editing tools with high precision are key to develop improved crops but current technologies to place new DNA into specific locations in plant genomes are low frequency and error-prone. Transposable elements (TEs) evolved to insert their DNA seamlessly into genomes, albeit in a quasi-random pattern. We developed a genome engineering tool that controls the TE insertion site and subsequently the delivery of any cargo attached to this TE. Using our tool, we demonstrated sequence-specific targeted delivery (guided by the CRISPR gRNA) of enhancers, an open reading frame and gene expression cassette into the genome of the model plant Arabidopsis, and we translated this technology to the crop soybean. We have engineered a ‘junk’ TE into a useful and accessible toolkit that enables the sequence-specific targeting of custom DNA into plant genomes.
Project description:We have developed a microarray intended for use in finding all transposons in a region of interest. By selectively amplifying and hybridizing transposon flanking DNA to our array, we can localize all transposons in the region present on our TIP-chip, a dense tiling array. We have tested our technology in yeast and have been successful. Keywords: transposon insertion profiling, genomic DNA, yeast
Project description:We used transposon insertion sequencing (Tn-Seq) to identify the genes that are required for in vitro growth and intramacrophage growth of the live vaccine strain of F. tularensis (LVS).
Project description:Transposon screens are powerful in vivo assays used to identify loci driving carcinogenesis. These loci are identified as Common Insertion Sites (CIS), i.e. regions with more transposon insertions than expected by chance. However, the identification of CIS is strongly affected by biases in the insertion behaviour of transposon systems. Here, we introduce Transmicron, a novel method that differs from previous methods by i) modelling neutral insertion rates based on chromatin accessibility, transcriptional activity, and sequence context, and ii) estimating oncogenic selection for each genomic region using Poisson regression to model insertion counts while controlling for neutral insertion rates. To assess the benefits of our approach, we generated a dataset applying two different transposon systems under comparable conditions. Benchmarking for enrichment of known cancer genes showed improved performance of Transmicron against state-of-the-art methods. Modelling neutral insertion rates allowed for better control of false positives and stronger agreement of the results between transposon systems. Moreover, using Poisson regression to consider intra-sample and inter-sample information proved beneficial in small and moderately-sized datasets. Transmicron is open-source and freely available. Overall, this study contributes to the understanding of transposon biology and introduces a novel approach to use this knowledge for discovering cancer driver genes.
Project description:Streptococcus pneumoniae is a major cause of serious infections such as pneumonia and meningitis in both children and adults worldwide. Here, we describe the development of a high-throughput genome-wide technique, Genomic Array Footprinting (GAF), for the identification of genes essential for this bacterium at various stages during infection. GAF enables negative screens by means of a combination of transposon mutagenesis and microarray technology for the detection of transposon insertion sites. We tested several methods for the identification of transposon insertion sites and found that amplification of DNA adjacent to the insertion site by PCR resulted in non-reproducible results, even when combined with an adapter. However, restriction of genomic DNA followed directly by in vitro transcription circumvented these problems. Analysis of parallel reactions generated with this method on a large mariner transposon library, showed that it was highly reproducible and correctly identified essential genes. Comparison of a mariner library to one generated with the in vivo transposition plasmid pGh:ISS1, showed that both have an equal degree of saturation, but that 9% of the genome is preferentially mutated by either one. The usefulness of GAF was demonstrated in a screen for genes essential for survival of zinc stress. This identified a gene encoding a putative cation efflux transporter, and its deletion resulted in an inability to grow under high zinc conditions. In conclusion, we developed a fast, versatile, specific, and high-throughput method for the identification of conditionally essential genes in S. pneumoniae. Keywords: GAF Identification of transposon insertion sites