Biology subjects

Gislard, M.

Publications and source records attributed to Gislard, M..

3 recordsLinked to original sources

bioRxiv2025

Chromosome-scale genome assembly of Xiphinema index uncovers an unparalleled epigenetic toolkit in invertebrates

Nematodes constitute the most speciose animal phylum, occupying an exceptionally broad range of biomes and encompassing free-living microbe-feeders, predators, and notorious plant or animal parasites. However, the limited availability of genome-scale resources for early-branching nematode clades has constrained our understanding of the molecular determinants underlying these multiple evolutionary adaptations. Here, we present the genome of the plant-parasitic nematode Xiphinema index, constituting the first telomere-to-telomere assembly for the order Dorylaimida, an early-branching nematode lineage. Phylogenetic analyses reveal that horizontal gene transfers (HGT) have played a pivotal role in the emergence of plant parasitism in this phylum. Remarkably, we identify the first documented case of a plant-derived HGT in a nematode genome. This gene encodes a predicted secreted parasitic effector, underscoring the diversity of evolutionary events that contributed to the parasitic arsenal. Our results suggest that, beyond bacteria and fungi, plants themselves have provided crucial genes for parasitism that may now be used by the nematodes to manipulate them. Our comparative genomic analyses across more than 70 nematode species further uncover an unprecedented epigenetic toolkit in an invertebrate genome. Indeed, X. index harbors a complete set of canonical DNA methyltransferases, a full-length ATRX chromatin remodeler, and 3D-chromatin architectural CTCF protein coding homolog. Consistent with this repertoire, we detected methylation at CpG genome-wide, which inversely correlates with gene expression and chromatin accessibility. Together, these findings reveal a vertebrate-like epigenetic machinery in an early-branching nematode and call for a fundamental reassessment of the prevailing epigenetic paradigm in nematodes and, more broadly, in animals.

genomics↗

bioRxiv2023

Spatio-temporal diversity and genetic architecture of pyrantel resistance in Cylicocyclus nassatus, the most abundant horse parasite

Cyathostomins are a complex of 50 intestinal parasite species infecting horses and wild equids. The massive administration of modern anthelmintic drugs has increased their relative abundance in horse helminth communities and selected drug-resistant isolates worldwide. Cylicocyclus nassatus is the most prevalent and the most abundant species. The tedious identification and isolation of these worms have hampered studies of their biology that remain largely uncharacterised. Here we have leveraged ultra-low input sequencing protocols to build a reference genome for the most prevalent horse strongyle species. Using this resource, we have established the first estimates of its genetic diversity and population structure on a gradient ranging from Ukraine (close to modern horse domestication area) to North America, while capturing a 19th-century snapshot of C. nassatus diversity in Egypt. Our results support a diverse and lowly structured global population. Modern populations displayed lower nucleotide diversity relative to the old North African isolate. We identified the first genetic candidates upon which pyrantel (an anthelmintic drug used in companion animals) selection likely applied in field populations, highlighting previously suspected genes coding for nicotinic acetylcholine receptor subunits, and identifying new candidates showing differential expression in independently evolved Caenorhabditis elegans lines. These results offer a first resource to widen current knowledge on cyathostomin biology, unravel novel aspects of pyrantel resistance mechanisms and provide candidate genes to track pyrantel resistance in the field.

genomics↗

bioRxiv2023

Genome sequence and annotation of Periconia digitata, a promising biocontrol agent of phytopathogenic oomycetes

The Periconia fungal genus belongs to the phylum Ascomycota, order Pleosporales, family Periconiaceae. Periconia are found in many habitats but little is known about their ecology. Several species from this genus produce bioactive molecules. Periconia digitata extracts were shown to be deadly active against the pine wilt nematode. Furthermore, P. digitata was shown to inhibit plant pathogenic oomycete Phytophthora parasitica. Because P. digitata has great potential as a biocontrol agent and high quality genomic resources are still lacking in the Periconiaceae family, we generated long-read genomic data for P. digitata. Using the PacBio Hifi sequencing technology, we obtained a highly-contiguous genome assembled in 13 chromosomes and totalling ca. 39 Mb. In addition, we produced a reference transcriptome, based on 12 different culture conditions, and proteomic data to support the genome annotation. Besides representing a new reference genome within the Periconiaceae, this work will contribute to our better understanding of the Eukaryotic tree of life and opens new possibilities in terms of biotechnological applications.

microbiology↗