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Bonfield, J. K.

Publications and source records attributed to Bonfield, J. K..

4 recordsLinked to original sources

Pangenome-guided sequence assembly via binary optimisation

De novo genome assembly is challenging in highly repetitive regions; however, reference-guided assemblers often suffer from bias. We propose a framework for pangenome-guided sequence assembly, which can resolve short-read data in complex regions without bias towards a single reference genome. Our method frames assembly as a graph traversal optimisation problem, which can be implemented on quantum computers. The pipeline first annotates pangenome graphs with estimated copy numbers for each node, then finds a path on the graph that best explains those copy numbers. On simulated data, our approach significantly reduces the number of contigs compared to de novo assemblers. While it introduces a small increase in inaccuracies, such as false joins, our optimisation-based methods are competitive with current exhaustive search techniques. They are also designed to scale more efficiently as the problem size grows and will run effectively on future quantum computers.

genomics↗

CRAM 3.1: Advances in the CRAM Format

MotivationCRAM has established itself as a high compression alternative to the BAM file format for DNA sequencing data. We describe updates to further improve this on modern sequencing instruments. ResultsWith Illumina data CRAM 3.1 is 7 to 15% smaller than the equivalent CRAM 3.0 file, and 50 to 70% smaller than the corresponding BAM file. Long-read technology shows more modest compression due to the presence of high-entropy signals. AvailabilityThe CRAM 3.0 specification is freely available from https://samtools.github.io/hts-specs/CRAMv3.pdf. The CRAM 3.1 improvements are available from https://github.com/samtools/hts-specs/pull/433, with OpenSource implementations in HTSlib and HTScodecs. Contactjkb@sanger.ac.uk Supplementary informationSupplementary data are available online

bioinformatics↗

HTSlib - C library for reading/writing high-throughput sequencing data

AbstractO_ST_ABSBackgroundC_ST_ABSSince the original publication of the VCF and SAM formats, an explosion of software tools have been created to process these data files. To facilitate this a library was produced out of the original SAMtools implementation, with a focus on performance and robustness. The file formats themselves have become international standards under the jurisdiction of the Global Alliance for Genomics and Health. FindingsWe present a software library for providing programmatic access to sequencing alignment and variant formats. It was born out of the widely used SAMtools and BCFtools applications. Considerable improvements have been made to the original code plus many new features including newer access protocols, the addition of the CRAM file format, better indexing and iterators, and better use of threading. ConclusionSince the original Samtools release, performance has been considerably improved, with a BAM read-write loop running 5 times faster and BAM to SAM conversion 13 times faster (both using 16 threads, compared to Samtools 0.1.19). Widespread adoption has seen HTSlib downloaded over a million times from GitHub and conda. The C library has been used directly by an estimated 900 GitHub projects and has been incorporated into Perl, Python, Rust and R, significantly expanding the number of uses via other languages. HTSlib is open source and is freely available from htslib.org under MIT / BSD license. Contactsamtools@sanger.ac.uk

bioinformatics↗

Crumble: reference free lossy compression of sequence quality values

MotivationThe bulk of space taken up by NGS sequencing CRAM files consists of per-base quality values. Most of these are unnecessary for variant calling, offering an opportunity for space saving.\n\nResultsOn the CHM1+CHM13 test set, a 17 fold reduction in quality storage can be achieved while maintaining variant calling accuracy.\n\nAvailabilityCrumble is OpenSource and can be obtained from https://github.com/jkbonfield/crumble.\n\nContactjkb@sanger.ac.uk\n\nSupplementary informationSupplementary data are available.

bioinformatics↗