Browsing by Author "Leblanc, Catherine"

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    Aldehyde perception induces specific molecular responses in Laminaria digitata and affects algal consumption by a specialist grazer
    (2023) Xing, Qikun; Cabioch, Lea; Desrut, Antoine; Le Corguille, Gildas; Rousvoal, Sylvie; Dartevelle, Laurence; Rolland, Elodie; Guitton, Yann; Potin, Philippe; Markov, Gabriel V.; Faugeron, Sylvain; Leblanc, Catherine
    In the marine environment, distance signaling based on water-borne cues occurs during interactions between macroalgae and herbivores. In the brown alga Laminaria digitata from North-Atlantic Brittany, oligoalginates elicitation or grazing was shown to induce chemical and transcriptomic regulations, as well as emission of a wide range of volatile aldehydes, but their biological roles as potential defense or warning signals in response to herbivores remain unknown. In this context, bioassays using the limpet Patella pellucida and L. digitata were carried out for determining the effects of algal transient incubation with 4-hydroxyhexenal (4-HHE), 4-hydroxynonenal (4-HNE) and dodecadienal on algal consumption by grazers. Simultaneously, we have developed metabolomic and transcriptomic approaches to study algal molecular responses after treatments of L. digitata with these chemical compounds. The results indicated that, unlike the treatment of the plantlets with 4-HNE or dodecadienal, treatment with 4-HHE decreases algal consumption by herbivores at 100 ng.ml(-1). Moreover, we showed that algal metabolome was significantly modified according to the type of aldehydes, and more specifically the metabolite pathways linked to fatty acid degradation. RNAseq analysis further showed that 4-HHE at 100 ng.ml(-1) can activate the regulation of genes related to oxylipin signaling pathways and specific responses, compared to oligoalginates elicitation. As kelp beds constitute complex ecosystems consisting of habitat and food source for marine herbivores, the algal perception of specific aldehydes leading to targeted molecular regulations could have an important biological role on kelps/grazers interactions.
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    Genome and metabolic network of "Candidatus Phaeomarinobacter ectocarpi" Ec32, a new candidate genus of Alphaproteobacteria frequently associated with brown algae
    (2014) Dittami, Simon M.; Barbeyron, Tristan; Boyen, Catherine; Cambefort, Jeanne; Collet, Guillaume; Delage, Ludovic; Gobet, Angelique; Groisillier, Agnes; Leblanc, Catherine; Michel, Gurvan; Scornet, Delphine; Siegel, Anne; Tapia, Javier E.; Tonon, Thierry
    Rhizobiales and related orders of Alphaproteobacteria comprise several genera of nodule-inducing symbiotic bacteria associated with plant roots. Here we describe the genome and the metabolic network of "Candidatus Phaeomarinobacter ectocarpi" Ec32, a member of a new candidate genus closely related to Rhizobiales and found in association with cultures of the filamentous brown algal model Ectocarpus. The "Ca. P. ectocarpi" genome encodes numerous metabolic pathways that may be relevant for this bacterium to interact with algae. Notably, it possesses a large set of glycoside hydrolases and transporters, which may serve to process and assimilate algal metabolites. It also harbors several proteins likely to be involved in the synthesis of algal hormones such as auxins and cytokinins, as well as the vitamins pyridoxine, biotin, and thiamine. As of today, "Ca. P. ectocarpi" has not been successfully cultured, and identical 16S rDNA sequences have been found exclusively associated with Ectocarpus. However, related sequences (>= 97% identity) have also been detected free-living and in a Fucus vesiculosus microbiome barcoding project, indicating that the candidate genus "Phaeomarinobacter" may comprise several species, which may colonize different niches.
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    Herbivore-induced chemical and molecular responses of the kelps Laminaria digitata and Lessonia spicata
    (2017) Ritter, Andres; Cabioch, Lea; Brillet-Gueguen, Loraine; Corre, Erwan; Cosse, Audrey; Dartevelle, Laurence; Durufle, Harold; Fasshauer, Carina; Goulitquer, Sophie; Thomas, Francois; Correa, Juan A.; Potin, Philippe; Faugeron, Sylvain; Leblanc, Catherine
    Kelps are founding species of temperate marine ecosystems, living in intertidal coastal areas where they are often challenged by generalist and specialist herbivores. As most sessile organisms, kelps develop defensive strategies to restrain grazing damage and preserve their own fitness during interactions with herbivores. To decipher some inducible defense and signaling mechanisms, we carried out metabolome and transcriptome analyses in two emblematic kelp species, Lessonia spicata from South Pacific coasts and Laminaria digitata from North Atlantic, when challenged with their main specialist herbivores. Mass spectrometry based metabolomics revealed large metabolic changes induced in these two brown algae following challenges with their own specialist herbivores. Targeted metabolic profiling of L. spicata further showed that free fatty acid (FFA) and amino acid (AA) metabolisms were particularly regulated under grazing. An early stress response was illustrated by the accumulation of Sulphur containing amino acids in the first twelve hours of herbivory pressure. At latter time periods (after 24 hours), we observed FFA liberation and eicosanoid oxylipins synthesis likely representing metabolites related to stress. Global transcriptomic analysis identified sets of candidate genes specifically induced by grazing in both kelps. qPCR analysis of the top candidate genes during a 48-hours time course validated the results. Most of these genes were particularly activated by herbivore challenge after 24 hours, suggesting that transcriptional reprogramming could be operated at this time period. We demonstrated the potential utility of these genes as molecular markers for herbivory by measuring their inductions in grazed individuals of field harvested L. digitata and L. spicata. By unravelling the regulation of some metabolites and genes following grazing pressure in two kelps representative of the two hemispheres, this work contributes to provide a set of herbivore-induced chemical and molecular responses in kelp species, showing similar inducible responses upon specialist herbivores in their respective ecosystems.
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    Señalización química y defensa en las algas pardas en interacción con los herbívoros.
    (2016) Cabioch, Léa; Leblanc, Catherine; Faugeron, Sylvain Wielfrid; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
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    The Ectocarpus genome and the independent evolution of multicellularity in brown algae
    (2010) Cock, J. Mark; Sterck, Lieven; Rouze, Pierre; Scornet, Delphine; Allen, Andrew E.; Amoutzias, Grigoris; Anthouard, Veronique; Artiguenave, Francois; Aury, Jean-Marc; Badger, Jonathan H.; Beszteri, Bank; Billiau, Kenny; Bonnet, Eric; Bothwell, John H.; Bowler, Chris; Boyen, Catherine; Brownlee, Colin; Carrano, Carl J.; Charrier, Benedicte; Cho, Ga Youn; Coelho, Susana M.; Collen, Jonas; Corre, Erwan; Da Silva, Corinne; Delage, Ludovic; Delaroque, Nicolas; Dittami, Simon M.; Doulbeau, Sylvie; Elias, Marek; Farnham, Garry; Gachon, Claire M. M.; Gschloessl, Bernhard; Heesch, Svenja; Jabbari, Kamel; Jubin, Claire; Kawai, Hiroshi; Kimura, Kei; Kloareg, Bernard; Kuepper, Frithjof C.; Lang, Daniel; Le Bail, Aude; Leblanc, Catherine; Lerouge, Patrice; Lohr, Martin; Lopez, Pascal J.; Martens, Cindy; Maumus, Florian; Michel, Gurvan; Miranda-Saavedra, Diego; Morales, Julia; Moreau, Herve; Motomura, Taizo; Nagasato, Chikako; Napoli, Carolyn A.; Nelson, David R.; Nyvall-Collen, Pi; Peters, Akira F.; Pommier, Cyril; Potin, Philippe; Poulain, Julie; Quesneville, Hadi; Read, Betsy; Rensing, Stefan A.; Ritter, Andres; Rousvoal, Sylvie; Samanta, Manoj; Samson, Gaelle; Schroeder, Declan C.; Segurens, Beatrice; Strittmatter, Martina; Tonon, Thierry; Tregear, James W.; Valentin, Klaus; von Dassow, Peter; Yamagishi, Takahiro; Van de Peer, Yves; Wincker, Patrick
    Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related(1). These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae(2-5), closely related to the kelps(6,7) (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic(2) approaches to explore these and other(4,5) aspects of brown algal biology further.