Emmanuelle d'Alençon

• PhD
• Group Leader at French National Institute for Agriculture, Food, and Environment (INRAE)

Some insects have holocentric chromosomes, with multiple kinetochores rather than a single centromere. They also lack the CENP-A and CENP-C proteins, suggesting a kinetochore assembly process different from that of monocentric chromosomes. The homolog of CENP-T was recently shown to bind silent chromatin and to play a key role in kinetochore assemb...

Background An invasion occurs when introduced species establish and maintain stable populations in areas outside of their native habitat. Adaptive evolution has been proposed to contribute to this process. The fall armyworm (Spodoptera frugiperda) is one of the major pest insects infesting maize in both invaded and native areas. The invasion of thi...

The fall armyworm (FAW) Spodoptera frugiperda is thought to have undergone a rapid ‘west-to-east’ spread since 2016 when it was first identified in western Africa. Between 2018 and 2020, it was recorded from South Asia (SA), Southeast Asia (SEA), East Asia (EA), and Pacific/Australia (PA). Population genomic analyses enabled the understanding of pa...

The fall armyworm (FAW; Spodoptera frugiperda) is one of the major agricultural pest insects. FAW is native to the Americas, and its invasion was first reported in West Africa in 2016. Then it quickly spread through Africa, Asia, and Oceania, becoming one of the main threats to corn production. We analyzed whole genome sequences of 177 FAW individu...

Background Divergent selection on host-plants is one of the main evolutionary forces driving ecological speciation in phytophagous insects. The ecological speciation might be challenging in the presence of gene flow and assortative mating because the direction of divergence is not necessarily the same between ecological selection (through host-plan...

Background: Divergent selection on host-plants is one of the main evolutionary forces driving ecological speciation in phytophagous insects. The ecological speciation might be challenging in the presence of gene flow and assortative mating because the direction of divergence is not necessarily the same between ecological selection (through host-pla...

Native to the Americas, the invasive Spodoptera frugiperda (fall armyworm; FAW) was reported in West Africa in 2016, followed by its chronological detection across the Old World and the hypothesis of an eastward Asia expansion. We explored population genomic signatures of American and Old World FAW and identified 12 maternal mitochondrial DNA genom...

Spodoptera frugiperda, the fall armyworm (FAW), is an important agricultural pest in the Americas and an emerging pest in sub-Saharan Africa, India, East-Asia and Australia, causing damage to major crops such as corn, sorghum and soybean. While FAW larvae are considered polyphagous, differences in diet preference have been described between two gen...

Background Eukaryotic genomes are packaged by Histone proteins in a structure called chromatin. There are different chromatin types. Euchromatin is typically associated with decondensed, transcriptionally active regions and heterochromatin to more condensed regions of the chromosomes. Methylation of Lysine 9 of Histone H3 (H3K9me) is a conserved bi...

Background The degree to which adaptation to same environment is determined by similar molecular mechanisms, is a topic of broad interest in evolutionary biology, as an indicator of evolutionary predictability. We wished to address if adaptation to the same host plant in phytophagous insects involved related gene expression patterns. We compared sR...

Eukaryotic genomes are packaged by Histone proteins in a structure called chromatin. There are different chromatin types. Euchromatin is typically associated with decondensed, transcriptionally active regions and heterochromatin to more condensed regions of the chromosomes. Methylation of Lysine 9 of Histone H3 (H3K9me) is a conserved biochemical m...

Field evolved resistance to insecticides is one of the main challenges in pest control. The fall armyworm (FAW) is a lepidopteran pest species causing severe crop losses, especially corn. While native to the Americas, the presence of FAW was confirmed in West Africa in 2016. Since then, the FAW has been detected in over 70 countries covering sub-Sa...

The noctuid genus Spodoptera currently consists of 31 species with varied host plant breadths, ranging from monophagous and oligophagous non-pest species to polyphagous pests of economic importance. Several of these pest species have become major invaders, colonizing multiple continents outside their native range. Such is the case of the infamous f...

Understanding the genetic basis of insecticide resistance is a key topic in agricultural ecology. The adaptive evolution of multi-copy detoxification genes has been interpreted as a cause of insecticide resistance, yet the same pattern can also be generated by the adaptation to host-plant defense toxins. In this study, we tested in the fall armywor...

Background The process of speciation involves differentiation of whole genome sequences between a pair of diverging taxa. In the absence of a geographic barrier and in the presence of gene flow, genomic differentiation may occur when the homogenizing effect of recombination is overcome across the whole genome. The fall armyworm is observed as two s...

The rapid wide-scale spread of fall armyworm (Spodoptera frugiperda) has caused serious crop losses globally. However, differences in the genetic background of subpopulations and the mechanisms of rapid adaptation behind the invasion are still not well understood. Here we report the assembly of a 390.38Mb chromosome-level genome of fall armyworm de...

A successful biological invasion involves survival in a newly occupied environment. If a population bottleneck occurs during an invasion, the resulting depletion of genetic variants could cause increased inbreeding depression and decreased adaptive potential, which may result in a fitness reduction. How invasive populations survive in the newly occ...

Accurate genomic knowledge can elucidate the global spread patterns of invasive pests. The high-profile invasive agricultural pest Spodoptera frugiperda (fall armyworm; FAW) is a case in point. Native to the Americas, the FAW was first reported in West Africa in 2016 and has rapidly spread to over 64 countries across the Old World, resulting in sig...

Insecticide resistance is a major main challenge in pest control, and understanding its genetic basis is a key topic in agricultural ecology. Detoxification genes are well-known genetic elements that play a key role in adaptation to xenobiotics. The adaptive evolution of detoxification genes by copy number variations has been interpreted as a cause...

The rapid wide-scale spread of fall armyworm (Spodoptera frugiperda) has caused serious crop losses globally. However, differences in the genetic background of subpopulations and the mechanisms of rapid adaptation behind the invasion are still not well understood. Here we report a 393.25-M chromosome-level genome assembly of fall armyworm with scaf...

Nous avons généré deux lignées d’insectes portant chacune une mutation perte-de-fonction dans l’un des deux gènes pro-phénoloxidase (Sf-PPO1 et Sf-PPO2). L’outil « CRISPR/Cas9 » est donc fonctionnel chez Spodoptera frugiperda. Les deux lignées obtenues, ainsi que la lignée double mutants (en court d’obtention), vont maintenant nous permettre de mie...

Nous avons généré deux lignées d’insectes portant chacune une mutation perte-de-fonction dans l’un des deux gènes pro-phénoloxidase (Sf-PPO1 et Sf-PPO2). L’outil « CRISPR/Cas9 » est donc fonctionnel chez Spodoptera frugiperda. Les deux lignées obtenues, ainsi que la lignée double mutants (en court d’obtention), vont maintenant nous permettre de mie...

Background: A change in the environment may impair development or survival of living organisms leading them to adapt to the change. The resulting adaptation trait may reverse, or become fixed in the population leading to evolution of species. Deciphering the molecular basis of adaptive traits can thus give evolutionary clues. In phytophagous insect...

The process of speciation involves whole genome differentiation by overcoming gene flow between diverging populations. We have ample knowledge which evolutionary forces may cause genomic differentiation, and several speciation models have been proposed to explain the transition from genetic to genomic differentiation. However, it is still unclear w...

Background The Lepidopteran ambidensovirus 1 isolated from Junonia coenia (hereafter JcDV) is an invertebrate parvovirus considered as a viral transduction vector as well as a potential tool for the biological control of insect pests. Previous works showed that JcDV-based circular plasmids experimentally integrate into insect cells genomic DNA. Me...

Raw DNA sequences obtained after sequencing of the PCR amplificates.

The tobacco cutworm, Spodoptera litura, is among the most widespread and destructive agricultural pests, feeding on over 100 crops throughout tropical and subtropical Asia. By genome sequencing, physical mapping and transcriptome analysis, we found that the gene families encoding receptors for bitter or toxic substances and detoxification enzymes,...

Emergence of polyphagous herbivorous insects entails significant adaptation to recognize, detoxify and digest a variety of host-plants. Despite of its biological and practical importance - since insects eat 20% of crops - no exhaustive analysis of gene repertoires required for adaptations in generalist insect herbivores has previously been performe...

Nowadays molecular species delimitation methods promote the identification of species boundaries within complex taxonomic groups by adopting innovative species concepts and theories (e.g. branching patterns, coalescence). As some of them can efficiently deal with large single-locus datasets, they could speed up the process of species discovery comp...

Herbivorous insects represent the most species-rich lineages of metazoans. The high rate of diversification in herbivorous insects is thought to result from their specialization to distinct host-plants, which creates conditions favorable for the build-up of reproductive isolation and speciation. These conditions rely on constraints against the opti...

The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differenc...

Background Spodoptera frugiperda (Noctuidae) is a major agricultural pest throughout the American continent. The highly polyphagous larvae are frequently devastating crops of importance such as corn, sorghum, cotton and grass. In addition, the Sf9 cell line, widely used in biochemistry for in vitro protein production, is derived from S. frugiperda...

This article documents the addition of 473 microsatellite marker loci and 71 pairs of single-nucleotide polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Barteria fistulosa, Bombus morio, Galaxias platei, Hematodinium perezi, Macrocentrus cingulum Brischke (a.k.a. M. ab...

Alignment of S. frugiperda LNCR rasiRNAs with long non coding RNA (LNCR). The sequence of LNCR is on the lower panel. The positions of cluster 1 and 2 LNCR rasiRNAs are labelled in red. (TIF)

The quality of total and small RNA isolated at different developmental stages of S. Frugiperda. Total RNA isolated from whole S. frugiperda body at three developmental stages (2.5-day old fertilised eggs, L2 larval stage and 12 days old pupae) was separated on A) 1% native agarose gel and stained with EtBr; B) 17% polyacrylamide/7 M urea denaturing...

Expression analysis of S. frugiperda long ncRNA (LNCR) during different developmental stages done by qRT PCR. Graphs present the relative LNCR copy number during development relative to the expression of ribosomal gene RPL37 used as endogenous control gene (E2- 2.5-day old fertilized eggs, L1–L6 larval stages, P- 12 days old pupae and A- adults). q...

Predicted secondary structures of S. frugiperda LNCR rasiRNAs. The LNCR rasiRNA sequences are folded on Mfold web server for nucleic acid folding and hybridization prediction - M. Zuker (http://mfold.bioinfo.rpi.edu/cgi-bin/rna-form1.cgi), using the default settings. Predicted secondary structure with the lowest free energy is presented. Free energ...

The presence of histone H3 modification during different developmental stages of S. frugiperda. A) Western blot showing the presence of histone H3 modification during the different developmental stages of S. frugiperda (E1- 1 day old eggs, E2- 2.5 days old eggs, L1–L6 larval stages, P- 12 days old pupae and A-adults). B) Graph presenting the normal...

The flow results of data filtration and distribution of sequenced small RNAs in three developmental stages of S. frugiperda (2.5 days old fertilized eggs, L2 larval stage and 12 days old pupae). The raw data in each library presents the sum of low and high quality reads. Low-quality reads were excluded from further analysis. High-quality reads pres...

Mapping of LNCR rasiRNAs to genomic regions. Position of the LNCR rasiRNAs on some of the S. frugiperda genomic regions that are cloned in bacterial artificial chromosome (BAC) and sequenced. Only perfect matches are presented. (PPTX)

Accession numbers of 46 LNCR rasiRNAs, 11 TE LNCR copies and LNCR. (PPTX)

Table of S. frugiperda LNCR rasiRNAs. LNCR rasiRNAs are sorted in cluster 1 and cluster 2 with their names, sequences, percentage in each of three libraries (2.5 days old fertilized eggs, L2 larval stage and 12 days old pupae) and their position on LNCR and the consensus DNA repeated element (TE LNCR consensus or Spodo2-B-R19-Map11_NoCat-consensus...

Repeat-associated small interfering RNAs (rasiRNAs) are derived from various genomic repetitive elements and ensure genomic stability by silencing endogenous transposable elements. Here we describe a novel subset of 46 rasiRNAs named LNCR rasiRNAs due to their homology with one long non-coding RNA (LNCR) of Spodoptera frugiperda. LNCR operates as t...

The discovery of an homolog of the human centromeric protein B, CENP-B, in an EST database of the holocentric insect species Spodoptera frugiperda prompted us to further characterize that gene because i) CENP-B has not been described in invertebrates yet ii) it should be a milestone in the molecular characterization of the holocentric centromere of...

The recent assembly of the silkworm Bombyx mori genome with 432 Mb on 28 holocentric chromosomes has become a reference in the genomic analysis of the very diverse Order of Lepidoptera. We sequenced BACs from two major pests, the noctuid moths Helicoverpa armigera and Spodoptera frugiperda, corresponding to 15 regions distributed on 11 B. mori chro...

We used preS2-S'-beta-galactosidase, a three domain fusion protein that aggregates extensively at 43 degrees C in the cytoplasm of Escherichia coli to search for multicopy suppressors of protein aggregation and inclusion bodies formation, and took advantage of the known differential solubility of preS2-S'-beta-galactosidase at 37 and 43 degrees C t...

The Lepidoptera Spodoptera frugiperda is a pest which causes widespread economic damage on a variety of crop plants. It is also well known through its famous Sf9 cell line which is used for numerous heterologous protein productions. Species of the Spodoptera genus are used as model for pesticide resistance and to study virus host interactions. A ge...

Two genomic tools for the study of Lepidoptera and the holocentric structure of their chromosomes are presented in this paper. A bacterial artificial chromosome (BAC) library was constructed using nuclear DNA partially digested with HindIII from eggs of Spodoptera frugiperda. The library contains a total of 36,864 clones with an average insert size...

In a large group of organisms including low G + C bacteria and eukaryotic cells, DNA synthesis at the replication fork strictly requires two distinct replicative DNA polymerases. These are designated pol C and DnaE in Bacillus subtilis. We recently proposed that DnaE might be preferentially involved in lagging strand synthesis, whereas pol C would...

The present work describes sequence and transcription of three Spodoptera frugiperda genes encoding 6-cysteine-rich peptides. Sequence alignments indicate that the predicted peptides belong to the insect defensin family, although phylogenetic analyses suggest they form a cluster distinct from that of other neopteran insect defensins. The three gene...

In an attempt to develop transgenic silkworm refractory to baculovirus Bombyx mori Nuclear Polyhedrosis Virus (BrnNPV), we exploited the RNAi mediated viral inhibition in two lepidopteran cell-lines, Sf9 and BrnN. As a first step, double stranded RNA was produced by in vitro transcription using T3/T7 RNA Polymerase, against an essential early viral...

In this report, we show that yccV, a gene of unknown function, encodes a protein having an affinity for a hemimethylated oriC DNA and that the protein negatively controls dnaA gene expression in vivo.

We studied DNA binding of a transcriptional repressor, CopF, displayed on a filamentous phage. Mutagenesis of a putative helix-turn-helix motif of CopF and of certain bases of the operator abolished the protein-DNA interaction, establishing the elements involved in CopF function and showing that phage display can be used to study repressor proteins...

The hemimethylated oriC binding activity of the E. coli heavy density membrane fraction (outer membrane) was investigated by DNase I footprinting experiments using membranes obtained from different replication stages of PC-2 (dnaCts) cells. The maximal binding activity was found at the beginning of replication cycle and then decreased gradually. Th...

The lacZ-hobH fusion clone, containing an Escherichia coli DNA segment located at 92 min on the chromosomal map, was screened as a producer of E. coli oriC hemi-methylated binding activity. We have purified the protein encoded by this locus to near homogeneity. The protein corresponds to the monomeric form of a non-specific acid phosphatase (NAP) w...

Nearly precise excision of a transposon related to Tn10 from an Escherichia coli plasmid was used as a model to study illegitimate DNA recombination between short direct repeats. The excision was stimulated 100-1000 times by induction of plasmid single-stranded DNA synthesis and did not involve transfer of DNA from the parental to the progeny molec...

Illegitimate recombination, which is one of the major causes of genome rearrangements, can occur in a number of ways. These might involve enzymes which cut and join DNA or enzymes which replicate DNA, as illustrated by two examples: (i) formation of deletions at the replication origin (ori) of an Escherichia coli bacteriophage, M13; and (ii) excisi...

Deletions form frequently in chimeric plasmids composed of M13mp2, pBR322, and pC194 (B. Michel and S. D. Ehrlich, Proc. Natl. Acad. Sci. USA 83:3386-3390, 1986). They are generated by joining of the nucleotide neighboring the nick site in the M13 replication origin to a nonadjacent nucleotide. This nucleotide is most often located within particula...