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Accueil > Départements > Biologie des Génomes > Robert DEBUCHY & Fabienne MALAGNAC : Différenciation sexuée et méiose chez les champignons

Publications de l’équipe


  • E. Dubois, N. Mathy, V. Régnier, J. Bischerour, C. Baudry, R. Trouslard, et M. Bétermier, « Multimerization properties of PiggyMac, a domesticated piggyBac transposase involved in programmed genome rearrangements », Nucleic Acids Research, 2017.
    Résumé : During sexual processes, the ciliate Paramecium eliminates 25-30% of germline DNA from its somatic genome. DNA elimination includes excision of ∼45 000 short, single-copy internal eliminated sequences (IESs) and depends upon PiggyMac (Pgm), a domesticated piggyBac transposase that is essential for DNA cleavage at IES ends. Pgm carries a core transposase region with a putative catalytic domain containing three conserved aspartic acids, and a downstream cysteine-rich (CR) domain. A C-terminal extension of unknown function is predicted to adopt a coiled-coil (CC) structure. To address the role of the three domains, we designed an in vivo complementation assay by expressing wild-type or mutant Pgm-GFP fusions in cells depleted for their endogenous Pgm. The DDD triad and the CR domain are essential for Pgm activity and mutations in either domain have a dominant-negative effect in wild-type cells. A mutant lacking the CC domain is partially active in the presence of limiting Pgm amounts, but inactive when Pgm is completely absent, suggesting that presence of the mutant protein increases the overall number of active complexes. We conclude that IES excision involves multiple Pgm subunits, of which at least a fraction must contain the CC domain.
    Mots-clés : DBG, DSMC, MICMAC.

  • H. Lalucque, F. Malagnac, K. Green, V. Gautier, P. Grognet, L. Chan Ho Tong, B. Scott, et P. Silar, « IDC2 and IDC3, two genes involved in cell non-autonomous signaling of fruiting body development in the model fungus Podospora anserina », Developmental Biology, vol. 421, nᵒ 2, p. 126-138, 2017.
    Résumé : Filamentous ascomycetes produce complex multicellular structures during sexual reproduction. Little is known about the genetic pathways enabling the construction of such structures. Here, with a combination of classical and reverse genetic methods, as well as genetic mosaic and graft analyses, we identify and provide evidence for key roles for two genes during the formation of perithecia, the sexual fruiting bodies, of the filamentous fungus Podospora anserina. Data indicate that the proteins coded by these two genes function cell-non-autonomously and that their activity depends upon conserved cysteines, making them good candidate for being involved in the transmission of a reactive oxygen species (ROS) signal generated by the PaNox1 NADPH oxidase inside the maturing fruiting body towards the PaMpk1 MAP kinase, which is located inside the underlying mycelium, in which nutrients are stored. These data provide important new insights to our understanding of how fungi build multicellular structures.
    Mots-clés : DBG, Developmental mutants, DSMC, Fungal development, Multicellular fruiting bodies, Perithecium, Podospora anserina.

  • S. Wang, T. Hassold, P. Hunt, M. A. White, D. Zickler, N. Kleckner, et L. Zhang, « Inefficient Crossover Maturation Underlies Elevated Aneuploidy in Human Female Meiosis », Cell, vol. 168, nᵒ 6, p. 977-989.e17, 2017.
    Résumé : Meiosis is the cellular program that underlies gamete formation. For this program, crossovers between homologous chromosomes play an essential mechanical role to ensure regular segregation. We present a detailed study of crossover formation in human male and female meiosis, enabled by modeling analysis. Results suggest that recombination in the two sexes proceeds analogously and efficiently through most stages. However, specifically in female (but not male), ∼25% of the intermediates that should mature into crossover products actually fail to do so. Further, this "female-specific crossover maturation inefficiency" is inferred to make major contributions to the high level of chromosome mis-segregation and resultant aneuploidy that uniquely afflicts human female oocytes (e.g., giving Down syndrome). Additionally, crossover levels on different chromosomes in the same nucleus tend to co-vary, an effect attributable to global per-nucleus modulation of chromatin loop size. Maturation inefficiency could potentially reflect an evolutionary advantage of increased aneuploidy for human females.
    Mots-clés : DBG, DSMC.

  • N. Xie, G. Ruprich-Robert, F. Chapeland-Leclerc, E. Coppin, H. Lalucque, S. Brun, R. Debuchy, et P. Silar, « Inositol-phosphate signaling as mediator for growth and sexual reproduction in Podospora anserina », Developmental Biology, 2017.
    Résumé : The molecular pathways involved in the development of multicellular fruiting bodies in fungi are still not well known. Especially, the interplay between the mycelium, the female tissues and the zygotic tissues of the fruiting bodies is poorly documented. Here, we describe PM154, a new strain of the model ascomycetes Podospora anserina able to mate with itself and that enabled the easy recovery of new mutants affected in fruiting body development. By complete genome sequencing of spod1, one of the new mutants, we identified an inositol phosphate polykinase gene as essential, especially for fruiting body development. A factor present in the wild type and diffusible in mutant hyphae was able to induce the development of the maternal tissues of the fruiting body in spod1, but failed to promote complete development of the zygotic ones. Addition of myo-inositol in the growth medium was able to increase the number of developing fruiting bodies in the wild type, but not in spod1. Overall, the data indicated that inositol and inositol polyphosphates were involved in promoting fruiting body maturation, but also in regulating the number of fruiting bodies that developed after fertilization. The same effect of inositol was seen in two other fungi, Sordaria macrospora and Chaetomium globosum. Key role of the inositol polyphosphate pathway during fruiting body maturation appears thus conserved during the evolution of Sordariales fungi.
    Mots-clés : DBG, Developmental mutants, DSMC, Fungal development, Inositol, Inositol kinase, Multicellular fruiting bodies, Perithecium, Podospora anserina.


  • K. Bomblies, G. Jones, C. Franklin, D. Zickler, et N. Kleckner, « The challenge of evolving stable polyploidy: could an increase in "crossover interference distance" play a central role? », Chromosoma, vol. 125, nᵒ 2, p. 287-300, 2016.
    Résumé : Whole genome duplication is a prominent feature of many highly evolved organisms, especially plants. When duplications occur within species, they yield genomes comprising multiple identical or very similar copies of each chromosome ("autopolyploids"). Such genomes face special challenges during meiosis, the specialized cellular program that underlies gamete formation for sexual reproduction. Comparisons between newly formed (neo)-autotetraploids and fully evolved autotetraploids suggest that these challenges are solved by specific restrictions on the positions of crossover recombination events and, thus, the positions of chiasmata, which govern the segregation of homologs at the first meiotic division. We propose that a critical feature in the evolution of these more effective chiasma patterns is an increase in the effective distance of meiotic crossover interference, which plays a central role in crossover positioning. We discuss the findings in several organisms, including the recent identification of relevant genes in Arabidopsis arenosa, that support this hypothesis.
    Mots-clés : Chiasmata, Chromosomes, Plant, Crossing Over, Genetic, Crossover interference, DBG, DSMC, Evolution, Molecular, Homologous chromosomes, Meiosis, Plants, Polyploidy, Recombination.

  • E. S. Naruzawa, F. Malagnac, et L. Bernier, « Effect of linoleic acid on reproduction and yeast–mycelium dimorphism in the Dutch elm disease pathogens », Botany, vol. 94, nᵒ 1, p. 31-39, 2016.

  • C. H. Sellem, J. - P. di Rago, J. - P. Lasserre, S. H. Ackerman, et A. Sainsard-Chanet, « Regulation of Aerobic Energy Metabolism in Podospora anserina by Two Paralogous Genes Encoding Structurally Different c-Subunits of ATP Synthase », PLOS Genetics, vol. 12, nᵒ 7, p. e1006161, juill. 2016.
    Mots-clés : BIOCELL, DBG, DSMC, FDMITO.

  • H. Takano-Rojas, D. Zickler, et L. Peraza-Reyes, « Peroxisome dynamics during development of the fungus Podospora anserina », Mycologia, vol. 108, nᵒ 3, p. 590-602, 2016.
    Résumé : Peroxisomes are versatile and dynamic organelles that are required for the development of diverse eukaryotic organisms. We demonstrated previously that in the fungus Podospora anserina different peroxisomal functions are required at distinct stages of sexual development, including the initiation and progression of meiocyte (ascus) development and the differentiation and germination of sexual spores (ascospores). Peroxisome assembly during these processes relies on the differential activity of the protein machinery that drives the import of proteins into the organelle, indicating a complex developmental regulation of peroxisome formation and activity. Here we demonstrate that peroxisome dynamics is also highly regulated during development. We show that peroxisomes in P. anserina are highly dynamic and respond to metabolic and environmental cues by undergoing changes in size, morphology and number. In addition, peroxisomes of vegetative and sexual cell types are structurally different. During sexual development peroxisome number increases at two stages: at early ascus differentiation and during ascospore formation. These processes are accompanied by changes in peroxisome structure and distribution, which include a cell-polarized concentration of peroxisomes at the beginning of ascus development, as well as a morphological transition from predominantly spherical to elongated shapes at the end of the first meiotic division. Further, the mostly tubular peroxisomes present from second meiotic division to early ascospore formation again become rounded during ascospore differentiation. Ultimately the number of peroxisomes dramatically decreases upon ascospore maturation. Our results reveal a precise regulation of peroxisome dynamics during sexual development and suggest that peroxisome constitution and function during development is defined by the coordinated regulation of the proteins that control peroxisome assembly and dynamics.
    Mots-clés : Cell Differentiation, DBG, DSMC, Fungal Proteins, Fungi, Gene Expression Regulation, Developmental, Gene Expression Regulation, Fungal, Genes, Mating Type, Fungal, Meiosis, peroxisome dynamics, Peroxisomes, Podospora, sexual development, Spores, Fungal.

  • P. S. Dyer, P. Inderbitzin, et Debuchy, Robert, « 14 Mating-Type Structure, Function, Regulation and Evolution in the Pezizomycotina », in Growth, Differentiation and Sexuality, J. Wendland, Éd. Cham: Springer International Publishing, 2016, p. 351-385.

  • L. Peraza-Reyes et F. Malagnac, « 16 Sexual Development in Fungi », in Growth, Differentiation and Sexuality, J. Wendland, Éd. Cham: Springer International Publishing, 2016, p. 407-455.

  • D. Zickler et E. Espagne, « Sordaria, a model system to uncover links between meiotic pairing and recombination », Seminars in Cell & Developmental Biology, vol. 54, p. 149-157, 2016.
    Résumé : The mycelial fungus Sordaria macrospora was first used as experimental system for meiotic recombination. This review shows that it provides also a powerful cytological system for dissecting chromosome dynamics in wild-type and mutant meioses. Fundamental cytogenetic findings include: (1) the identification of presynaptic alignment as a key step in pairing of homologous chromosomes. (2) The discovery that biochemical complexes that mediate recombination at the DNA level concomitantly mediate pairing of homologs. (3) This pairing process involves not only resolution but also avoidance of chromosomal entanglements and the resolution system includes dissolution of constraining DNA recombination interactions, achieved by a unique role of Mlh1. (4) Discovery that the central components of the synaptonemal complex directly mediate the re-localization of the recombination proteins from on-axis to in-between homologue axis positions. (5) Identification of putative STUbL protein Hei10 as a structure-based signal transduction molecule that coordinates progression and differentiation of recombinational interactions at multiple stages. (6) Discovery that a single interference process mediates both nucleation of the SC and designation of crossover sites, thereby ensuring even spacing of both features. (7) Discovery of local modulation of sister-chromatid cohesion at sites of crossover recombination.
    Mots-clés : Bouquet, DBG, DSMC, Meiotic recombination, Pairing, Sordaria, Synaptonemal Complex.

  • D. Zickler et N. Kleckner, « A few of our favorite things: Pairing, the bouquet, crossover interference and evolution of meiosis », Seminars in Cell & Developmental Biology, vol. 54, p. 135-148, 2016.
    Mots-clés : Bouquet, Crossover interference, DBG, DSMC, Meiosis, Pairing.


  • A. Goarin, P. Silar, et F. Malagnac, « Gene replacement in Penicillium roqueforti », Current Genetics, vol. 61, nᵒ 2, p. 203-210, 2015.
    Résumé : Most cheese-making filamentous fungi lack suitable molecular tools to improve their biotechnology potential. Penicillium roqueforti, a species of high industrial importance, would benefit from functional data yielded by molecular genetic approaches. This work provides the first example of gene replacement by homologous recombination in P. roqueforti, demonstrating that knockout experiments can be performed in this fungus. To do so, we improved the existing transformation method to integrate transgenes into P. roqueforti genome. In the meantime, we cloned the PrNiaD gene, which encodes a NADPH-dependent nitrate reductase that reduces nitrate to nitrite. Then, we performed a deletion of the PrNiaD gene from P. roqueforti strain AGO. The ΔPrNiaD mutant strain is more resistant to chlorate-containing medium than the wild-type strain, but did not grow on nitrate-containing medium. Because genomic data are now available, we believe that generating selective deletions of candidate genes will be a key step to open the way for a comprehensive exploration of gene function in P. roqueforti.
    Mots-clés : Cheese, DBG, DSMC, Gene Knockout Techniques, Genetic Engineering, Homologous Recombination, Humans, Nitrate Reductase (NADPH), Penicillium.

  • A. Humbert, E. Bovier, C. H. Sellem, et A. Sainsard-Chanet, « Deletion of the MED13 and CDK8 subunits of the Mediator improves the phenotype of a long-lived respiratory deficient mutant of Podospora anserina », Fungal Genetics and Biology, vol. 82, p. 228-237, 2015.
    Mots-clés : BIOCELL, Cell Respiration, Cyclin-Dependent Kinase 8, DBG, DSMC, Expression of glycolysis genes, FDMITO, Fungal Proteins, Gene Expression Regulation, Fungal, Gene Silencing, Glycolysis, Kinase module of Mediator, oxidative stress, Phenotype, Podospora, Podospora anserina, Protein Subunits, Retrograde regulation, Sequence Deletion, Transcription, Genetic.

  • Z. Liang, D. Zickler, M. Prentiss, F. S. Chang, G. Witz, K. Maeshima, et N. Kleckner, « Chromosomes Progress to Metaphase in Multiple Discrete Steps via Global Compaction/Expansion Cycles », Cell, vol. 161, nᵒ 5, p. 1124-1137, 2015.
    Résumé : Mammalian mitotic chromosome morphogenesis was analyzed by 4D live-cell and snapshot deconvolution fluorescence imaging. Prophase chromosomes, whose organization was previously unknown, are revealed to comprise co-oriented sister linear loop arrays displayed along a single, peripheral, regularly kinked topoisomerase II/cohesin/condensin II axis. Thereafter, rather than smooth, progressive compaction as generally envisioned, progression to metaphase is a discontinuous process involving chromosome expansion as well as compaction. At late prophase, dependent on topoisomerase II and with concomitant cohesin release, chromosomes expand, axes split and straighten, and chromatin loops transit to a radial disposition around now-central axes. Finally, chromosomes globally compact, giving the metaphase state. These patterns are consistent with the hypothesis that the molecular events of chromosome morphogenesis are governed by accumulation and release of chromosome stress, created by chromatin compaction and expansion. Chromosome state could evolve analogously throughout the cell cycle.
    Mots-clés : Adenosine Triphosphatases, Animals, Cell Cycle Proteins, Cell Line, Chromosomal Proteins, Non-Histone, Chromosomes, Mammalian, DBG, Deer, DNA Topoisomerases, Type II, DNA-Binding Proteins, DSMC, HeLa Cells, Humans, Metaphase, Microscopy, Fluorescence, Mitosis, Multiprotein Complexes, Swine.

  • J. Ropars, R. C. Rodríguez de la Vega, M. López-Villavicencio, J. Gouzy, E. Sallet, É. Dumas, S. Lacoste, R. Debuchy, J. Dupont, A. Branca, et T. Giraud, « Adaptive Horizontal Gene Transfers between Multiple Cheese-Associated Fungi », Current biology: CB, vol. 25, nᵒ 19, p. 2562-2569, 2015.
    Résumé : Domestication is an excellent model for studies of adaptation because it involves recent and strong selection on a few, identified traits [1-5]. Few studies have focused on the domestication of fungi, with notable exceptions [6-11], despite their importance to bioindustry [12] and to a general understanding of adaptation in eukaryotes [5]. Penicillium fungi are ubiquitous molds among which two distantly related species have been independently selected for cheese making-P. roqueforti for blue cheeses like Roquefort and P. camemberti for soft cheeses like Camembert. The selected traits include morphology, aromatic profile, lipolytic and proteolytic activities, and ability to grow at low temperatures, in a matrix containing bacterial and fungal competitors [13-15]. By comparing the genomes of ten Penicillium species, we show that adaptation to cheese was associated with multiple recent horizontal transfers of large genomic regions carrying crucial metabolic genes. We identified seven horizontally transferred regions (HTRs) spanning more than 10 kb each, flanked by specific transposable elements, and displaying nearly 100% identity between distant Penicillium species. Two HTRs carried genes with functions involved in the utilization of cheese nutrients or competition and were found nearly identical in multiple strains and species of cheese-associated Penicillium fungi, indicating recent selective sweeps; they were experimentally associated with faster growth and greater competitiveness on cheese and contained genes highly expressed in the early stage of cheese maturation. These findings have industrial and food safety implications and improve our understanding of the processes of adaptation to rapid environmental changes.
    Mots-clés : Adaptation, Biological, Cheese, CheesyTer, convergence, DBG, DNA, Fungal, DSMC, Food Microbiology, food spoiler, Fungi, gene expression, Gene Transfer, Horizontal, HGT, parallel adaptation, Penicillium, Phenotype, Wallaby.

  • S. Wang, D. Zickler, N. Kleckner, et L. Zhang, « Meiotic crossover patterns: Obligatory crossover, interference and homeostasis in a single process », Cell Cycle, vol. 14, nᵒ 3, p. 305-314, 2015.

  • D. Zickler et N. Kleckner, « Recombination, Pairing, and Synapsis of Homologs during Meiosis », Cold Spring Harbor Perspectives in Biology, vol. 7, nᵒ 6, 2015.
    Résumé : Recombination is a prominent feature of meiosis in which it plays an important role in increasing genetic diversity during inheritance. Additionally, in most organisms, recombination also plays mechanical roles in chromosomal processes, most notably to mediate pairing of homologous chromosomes during prophase and, ultimately, to ensure regular segregation of homologous chromosomes when they separate at the first meiotic division. Recombinational interactions are also subject to important spatial patterning at both early and late stages. Recombination-mediated processes occur in physical and functional linkage with meiotic axial chromosome structure, with interplay in both directions, before, during, and after formation and dissolution of the synaptonemal complex (SC), a highly conserved meiosis-specific structure that links homolog axes along their lengths. These diverse processes also are integrated with recombination-independent interactions between homologous chromosomes, nonhomology-based chromosome couplings/clusterings, and diverse types of chromosome movement. This review provides an overview of these diverse processes and their interrelationships.
    Mots-clés : Animals, Chromosome Pairing, Chromosomes, DBG, DNA Breaks, Double-Stranded, DSMC, Humans, Meiosis, Recombination, Genetic, Synaptonemal Complex.
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