The decoupled evolution of the organellar genomes of Silene nutans leads to distinct roles in the speciation process.

There is growing evidence that cytonuclear incompatibilities (i.e. disruption of cytonuclear coadaptation) might contribute to the speciation process.

Reproductive isolation among lineages of Silene nutans (Caryophyllaceae): A potential involvement of plastid-nuclear incompatibilities.

Early stages of speciation in plants might involve genetic incompatibilities between plastid and nuclear genomes, leading to inter-lineage hybrid breakdown due to the disruption between co-adapted plastid and nuclear genes encoding subunits of the same plastid protein complexes. We tested this hypothesis in Silene nutans, a gynodioecious Caryophyllaceae, where four distinct genetic lineages exhibited strong reproductive isolation among each other, resulting in chlorotic or variegated hybrids. By sequencing the whole gene content of the four plastomes through gene capture, and a large part of the nuclear genes encoding plastid subunits from RNAseq data, we searched for non-synonymous substitutions fixed in each lineage on both genomes.

yacrd and fpa: upstream tools for long-read genome assembly.

Motivation: Genome assembly is increasingly performed on long, uncorrected reads. Assembly quality may be degraded due to unfiltered chimeric reads; also, the storage of all read overlaps can take up to terabytes of disk space.

Results: We introduce two tools: yacrd for chimera removal and read scrubbing, and fpa for filtering out spurious overlaps.

Use of whole-genome sequencing in the molecular investigation of care-associated HCoV-OC43 infections in a hematopoietic stem cell transplant unit.

Background: While respiratory viral infections are recognized as a frequent cause of illness in hematopoietic stem cell transplantation (HSCT) recipients, HCoV-OC43 infections have rarely been investigated as healthcare-associated infections in this population.

Objectives: In this report, HCoV-OC43 isolates collected from HSCT patients were retrospectively characterized to identify potential clusters of infection that may stand for a hospital transmission.

Study Design: Whole-genome and S gene sequences were obtained from nasal swabs using next-generation sequencing and phylogenetic trees were constructed.

Complete Sequence, Multichromosomal Architecture and Transcriptome Analysis of the Mitochondrial Genome.

Mitochondrial genomes (mitogenomes) in higher plants can induce cytoplasmic male sterility and be somehow involved in nuclear-cytoplasmic interactions affecting plant growth and agronomic performance. They are larger and more complex than in other eukaryotes, due to their recombinogenic nature. For most plants, the mitochondrial DNA (mtDNA) can be represented as a single circular chromosome, the so-called master molecule, which includes repeated sequences that recombine frequently, generating sub-genomic molecules in various proportions.

Graph analysis of fragmented long-read bacterial genome assemblies.

Motivation: Long-read genome assembly tools are expected to reconstruct bacterial genomes nearly perfectly; however, they still produce fragmented assemblies in some cases. It would be beneficial to understand whether these cases are intrinsically impossible to resolve, or if assemblers are at fault, implying that genomes could be refined or even finished with little to no additional experimental cost.

Results: We propose a set of computational techniques to assist inspection of fragmented bacterial genome assemblies, through careful analysis of assembly graphs.

A complete protocol for whole-genome sequencing of virus from clinical samples: Application to coronavirus OC43.

Genome sequencing of virus has become a useful tool for better understanding of virus pathogenicity and epidemiological surveillance. Obtaining virus genome sequence directly from clinical samples is still a challenging task due to the low load of virus genetic material compared to the host DNA, and to the difficulty to get an accurate genome assembly. Here we introduce a complete sequencing and analyzing protocol called V-ASAP for Virus Amplicon Sequencing Assembly Pipeline.

Assisted transcriptome reconstruction and splicing orthology.

Background: Transcriptome reconstruction, defined as the identification of all protein isoforms that may be expressed by a gene, is a notably difficult computational task. With real data, the best methods based on RNA-seq data identify barely 21 % of the expressed transcripts. While waiting for algorithms and sequencing techniques to improve - as has been strongly suggested in the literature - it is important to evaluate assisted transcriptome prediction; this is the question of how alternative transcription in one species performs as a predictor of protein isoforms in another relatively close species.

ProCARs: Progressive Reconstruction of Ancestral Gene Orders.

Background: In the context of ancestral gene order reconstruction from extant genomes, there exist two main computational approaches: rearrangement-based, and homology-based methods. The rearrangement-based methods consist in minimizing a total rearrangement distance on the branches of a species tree. The homology-based methods consist in the detection of a set of potential ancestral contiguity features, followed by the assembling of these features into Contiguous Ancestral Regions (CARs).

Retention-error patterns in complex alphanumeric serial-recall tasks.

We propose a new method based on an algorithm usually dedicated to DNA sequence alignment in order to both reliably score short-term memory performance on immediate serial-recall tasks and analyse retention-error patterns. There can be considerable confusion on how performance on immediate serial list recall tasks is scored, especially when the to-be-remembered items are sampled with replacement. We discuss the utility of sequence-alignment algorithms to compare the stimuli to the participants' responses.

Genome dedoubling by DCJ and reversal.

Background: Segmental duplications in genomes have been studied for many years. Recently, several studies have highlighted a biological phenomenon called breakpoint-duplication that apparently associates a significant proportion of segmental duplications in Mammals, and the Drosophila species group, to breakpoints in rearrangement events.

Results: In this paper, we introduce and study a combinatorial problem, inspired from the breakpoint-duplication phenomenon, called the Genome Dedoubling Problem.

TFM-Explorer: mining cis-regulatory regions in genomes.

DNA-binding transcription factors (TFs) play a central role in transcription regulation, and computational approaches that help in elucidating complex mechanisms governing this basic biological process are of great use. In this perspective, we present the TFM-Explorer web server that is a toolbox to identify putative TF binding sites within a set of upstream regulatory sequences of genes sharing some regulatory mechanisms. TFM-Explorer finds local regions showing overrepresentation of binding sites.

A scenario of mitochondrial genome evolution in maize based on rearrangement events.

Background: Despite their monophyletic origin, animal and plant mitochondrial genomes have been described as exhibiting different modes of evolution. Indeed, plant mitochondrial genomes feature a larger size, a lower mutation rate and more rearrangements than their animal counterparts. Gene order variation in animal mitochondrial genomes is often described as being due to translocation and inversion events, but tandem duplication followed by loss has also been proposed as an alternative process.

Efficient and accurate P-value computation for Position Weight Matrices.

Background: Position Weight Matrices (PWMs) are probabilistic representations of signals in sequences. They are widely used to model approximate patterns in DNA or in protein sequences. The usage of PWMs needs as a prerequisite to knowing the statistical significance of a word according to its score.

Evolution of plant-like crystalline storage polysaccharide in the protozoan parasite Toxoplasma gondii argues for a red alga ancestry.

Single-celled apicomplexan parasites are known to cause major diseases in humans and animals including malaria, toxoplasmosis, and coccidiosis. The presence of apicoplasts with the remnant of a plastid-like DNA argues that these parasites evolved from photosynthetic ancestors possibly related to the dinoflagellates. Toxoplasma gondii displays amylopectin-like polymers within the cytoplasm of the dormant brain cysts.