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Eche, S.

Publications and source records attributed to Eche, S..

2 recordsLinked to original sources

SeqPanther: Sequence manipulation and mutation statistics toolset

Pathogen genomes harbor critical information necessary to support genomic investigations that inform public health interventions such as treatment, control, and eradication. To extract this information, their sequences are analysed to identify structural variations such as single nucleotide polymorphisms (SNPs) and insertions and deletions (indels) that may be associated with phenotypes of interest. Typically, this involves generating a consensus sequence from raw reads, aligning it to a reference and identifying positions where variations occur. Several pipelines exist to map raw reads and assemble whole genomes for downstream analysis. However, there is no easy to use, freely available bioinformatics quality control (QC) tool to explore mappings for both positional codons and nucleotide distributions in mapped short reads of microbial genomes. To address this problem, we have developed a fast and accurate tool to summarise read counts associated with codons, nucleotides, and indels in mapped next-generation sequencing (NGS) short reads. The tool, developed in Python, also provides a visualization of the genome sequencing depth and coverage. Furthermore, the tool can be run in single or batch mode, where several genomes need to be analysed. Our tool produces a text-based report that enables quick review or can be imported into any analytical tool for upstream analysis. Additionally, the tool also provides functionality to modify the consensus sequences by adding, masking, or restoring to wild type mutations specified by the user. AvailabilitySeqPanther is available at https://github.com/codemeleon/seqPanther, along with the necessary documentation for installation and usage.

bioinformatics↗

Molecular analysis of Drosophila melanogaster B chromosomes reveals their origin, composition, and structure

The number of chromosomes carried by an individual species is one of its defining characteristics. Some species, however, can also carry supernumerary chromosomes referred to as B chromosomes. B chromosomes were recently identified in a laboratory stock of Drosophila melanogaster--an established model organism with a wealth of genetic and genomic resources--enabling us to subject them to extensive molecular analysis. We isolated the B chromosomes by pulsed-field gel electrophoresis and determined their composition through next-generation sequencing. Although these B chromosomes carry no known euchromatic sequence, they are rich in transposable elements and long arrays of short nucleotide repeats, the most abundant being the uncharacterized AAGAT satellite repeat. Fluorescent in-situ hybridization on metaphase chromosome spreads revealed this repeat is located on Chromosome 4, strongly suggesting the origin of the B chromosomes is Chromosome 4. Cytological and quantitative comparisons of signal intensity between Chromosome 4 and the B chromosomes supports the hypothesis that the structure of the B chromosome is an isochromosome. We also report the identification of a new B chromosome variant in a related laboratory stock. This B chromosome has a similar repeat signature as the original but is smaller and much less prevalent. We examined additional stocks with similar genotypes and did not find B chromosomes, but did find these stocks lacked the AAGAT satellite repeat. Our molecular characterization of D. melanogaster B chromosomes is the first step towards understanding how supernumerary chromosomes arise from essential chromosomes and what may be necessary for their stable inheritance.

genetics↗