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DGIMI - Diversity, Genomes and Insects-Microorganisms Interactions

DGIMI is a joint research unit supervised by INRAE and the University of Montpellier. It is located on the Triolet campus of the University of Montpellier, and houses staff from both INRAE and UM.

The research carried out by UMR DGIMI is devoted to the study of interaction mechanisms between insect crop pests, their pathogens and parasites, and their host plants. This research takes into account the diversity of the partners and is based on knowledge of their genomes.

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HAL : Dernières publications

  • [hal-04941032] A fi rst characterization of kinetochore proteins in theholocentric insect Spodoptera frugiperda

    Abstract Insects with holocentric chromosomes have a centromere spread all over their length and are devoid of the proteins CENP-A and CENP-C, suggesting a different kinetochore assembly process compared to that in monocentrics. Very recently, the homolog of CENP-T was shown to play a key role in kinetochore assembly in Bombyx mori and to bind to silent chromatin regions. However, nothing is known in other holocentric insects. In this paper, we set up a protocol to silence the kinetochore genes cenp -L, cenp -S, cenp -X and ndc 80 and searched for chromosome segregation defects in Spodoptera frugiperda cells. We also analyzed their expression pattern in the insect. As shown by immunofluorescence microscopy and RT-QPCR, we succeeded to silence target genes efficiently by transfection with dsRNA. In Sf9 cells depleted for CENP-L and NDC80, by immunofluorescence microscopy, we observed an increase of mitotic indices linked to metaphase arrest and, respectively unaligned chromosomes and multipolar spindles. In cells depleted for CENP-S and CENP-X, the mitotic indices were unchanged and no division defects were observed. Except cenp -S and X, kinetochore genes were overexpressed in gonadal versus somatic tissues. We conclude that CENP-L and NDC80 play a major role in chromosome segregation, while the function of CENP-S and -X are still unknown. We started to characterize the kinetochore proteins (CENP-L, CENP-S, CENP-X, NDC80), a prerequisite for holocentromere identification in S. frugiperda . We provide the first clues on CENP-L in Lepidoptera, a protein playing a central role in the structure of the Constitutive Centromere Associated Network in monocentrics

    ano.nymous@ccsd.cnrs.fr.invalid (Emmanuelle d'Alençon) 11 Feb 2025

    https://hal.inrae.fr/hal-04941032v1
  • [hal-04777951] Association of poultry vaccination with the interspecies transmission and molecular evolution of H5 subtype avian influenza virus

    The effectiveness of vaccinating poultry in preventing the transmission of highly pathogenic avian influenza viruses (AIVs) has been questioned for years and its impact on wild birds is uncertain 1–3 . Here we reconstruct movements of H5 subtype AIV lineages among vaccinated poultry, unvaccinated poultry, and wild birds, worldwide from 1996 to 2023. We find that lineage transitions among host types are lagged and that movements from wild birds to unvaccinated poultry were more frequent than those from wild birds to vaccinated poultry. However, we also find that the HA gene of the AIV lineage that circulated predominately among Chinese poultry with high vaccination coverage underwent faster evolution and greater nonsynonymous divergence than other lineages. Further, this Chinese poultry lineage contained more codons inferred to be under positive selection, including at known antigenic sites, and its rates of nonsynonymous divergence and adaptative fixation increased after mass poultry vaccination began. Our results indicate that the epidemiological, ecological and evolutionary consequences of widespread AIV vaccination in poultry may be linked in complex ways, and that much work is needed to better understand how such interventions may affect AIV transmission to, within and from wild birds.

    ano.nymous@ccsd.cnrs.fr.invalid (Bingying Li) 06 Feb 2025

    https://hal.inrae.fr/hal-04777951v2
  • [hal-04867733] Deep Sequencing Analysis of Virome Components, Viral Gene Expression and Antiviral RNAi Responses in Myzus persicae Aphids

    <div><p>The green peach aphid (Myzus persicae) is a generalist pest damaging crops and transmitting viral pathogens. Using Illumina sequencing of small (s)RNAs and poly(A)-enriched long RNAs, we analyzed aphid virome components, viral gene expression and antiviral RNA interference (RNAi) responses. Myzus persicae densovirus (family Parvoviridae), a single-stranded (ss)DNA virus persisting in the aphid population, produced 22 nucleotide sRNAs from both strands of the entire genome, including 5 ′ -and 3 ′ -inverted terminal repeats. These sRNAs likely represent Dicer-dependent small interfering (si)RNAs, whose double-stranded RNA precursors are produced by readthrough transcription beyond poly(A) signals of the converging leftward and rightward transcription units, mapped here with Illumina reads. Additionally, the densovirus produced 26-28 nucleotide sRNAs, comprising those enriched in 5 ′ -terminal uridine and mostly derived from readthrough transcripts and those enriched in adenosine at position 10 from their 5 ′ -end and mostly derived from viral mRNAs. These sRNAs likely represent PIWI-interacting RNAs generated by a ping-pong mechanism. A novel ssRNA virus, reconstructed from sRNAs and classified into the family Flaviviridae, co-persisted with the densovirus and produced 22 nucleotide siRNAs from the entire genome. Aphids fed on plants versus artificial diets exhibited distinct RNAi responses affecting densovirus transcription and flavivirus subgenomic RNA production. In aphids vectoring turnip yellows virus (family Solemoviridae), a complete virus genome was reconstituted from 21, 22 and 24 nucleotide viral siRNAs likely acquired with plant phloem sap. Collectively, deep-sequencing analysis allowed for the identification and de novo reconstruction of M. persicae virome components and uncovered RNAi mechanisms regulating viral gene expression and replication.</p></div>

    ano.nymous@ccsd.cnrs.fr.invalid (Natalia Sukhikh) 06 Jan 2025

    https://hal.inrae.fr/hal-04867733v1

News

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article

24 February 2025

By: K.Nam ., N.Nègre , I. Seninet

Postdoctoral Position in CRISPR/Cas9 Gene Editing in Insects (University of Montpellier)

Location: UMR-DGIMI, University of Montpellier, France / Duration: 18 months / Start Date: Preferably from April 2025
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A University of Montpellier's Associated Professor in microbiology position (sections 64-65) has been created in DGIMI

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Applications must be submitted on Odyssée before 04/04/2025.

A new scientific publication

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Invasive populations in Senegal show evidence of adaptive evolution on CYP450 genes that may explain their adaptation to maize

photo Peter Heeling

Website under restructuring

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Our website is currently being restructured.