Bénédicte Charrier, Juliet C. Coates, Ioanna Stavridou
Bénédicte Charrier, Juliet C. Coates, Ioanna Stavridou
The life cycle of the brown alga Ectocarpus involves an alternation between two multicellular generations, the gametophyte and the sporophyte. When the IMMEDIATE UPRIGHT (IMM) gene is mutated, the sporophyte generation loses its extensive basal system and adopts a developmental pattern more similar to that of the gametophyte. The mutant exhibits no phenotype during the gametophyte stage suggesting that the deployment of the extensive basal system, directed by IMM, is an evolutionary innovation specific to the sporophyte generation. Identification of the IMM gene revealed that it is a member of a large, rapidly evolving family of genes, which was called the EsV-1-7 domain family. EsV-1-7 domain genes exhibit an unusual distribution across the eukaryotic tree of life and were found in several viral genomes, suggesting horizontal transfer between eukaryotic lineages, perhaps mediated by viruses. IMMEDIATE UPRIGHT (IMM) is the first macroalgal developmental gene to have been identified by a forward genetic approach and therefore represents a major step towards the emergence of macroalgal developmental biology.
References
Nicolas Macaisne, Fuli Liu, Delphine Scornet, Akira F. Peters, Agnieszka Lipinska, Marie-Mathilde Perrineau, Antoine Henry, Martina Strittmatter, Susana M. Coelho, J. Mark Cock (2017). The Ectocarpus IMMEDIATE UPRIGHT gene encodes a member of a novel family of cysteine-rich proteins with an unusual distribution across the eukaryotes. Development 2017 144: 409-418; doi: 10.1242/dev.141523
Development "In this Issue". Evolving an atypical developmental programme with IMM. Development 2017 144: e0301
Article in The Node. http://thenode.biologists.com/people-behind-papers-12/interview/
Department"Integrative Biology of Marine Models" (LBI2M, UMR8227 CNRS-UPMC)
Marine Glycobiology group
Place : Station BIologique de Roscoff (CNRS/UPMC)
Supervisor
Dr. François Thomas : fthomas@sb-roscoff.fr
Dr. Benoit Sarels : benoit.sarels@sb-roscoff.fr
The course, which consists of lectures, tutorials and computer based exercises, aims to highlight the crucial role of marine genomics for the understanding of the marine environment and for a sustainable use of its resources. Advanced PhD students and junior post-docs are encouraged to apply.
The deadline for application is April 3rd 2017.
Nic Blouin, U Rhode Island, USA
Jonas Collén, SB-Roscoff, FR
Matthias Obst, U Gothenburg, SE
Nathalie Turque, EMBRC-France, FR
Daniel Vaulot, SB-Roscoff, FR
Filip Volckaert, U Leuven, BE
We ended up recognizing 15 cryptic species within the Ectocarpus subgroup siliculosi using three independent species delimitation approaches on a sampling of 729 Ectocarpus specimens collected mainly along the European and Chilean coasts. The 15 species showed different patterns of geographic distribution, varying from rare species with narrow ranges to common cosmopolitan species (E. siliculosus and E. crouaniorum). Our results demonstrated that the sequenced genome Ectocarpus strain, actually used as model species for brown algae and previously recognized as E. siliculosus, is in reality a rare unnamed species only present in Peru and the Northern coast of Chile. Another interesting observation is that several of the different cryptic species have been observed to occupy different spatio-temporal ecological niches related to different tide levels and/or host specificity. Finally, our analyses suggest the existence of incomplete lineage sorting or introgression between five of these 15 recently diverging lineages and the possible existence of different levels of reproductive barriers within this species complex. All these results open a very interesting field of research deciphering the process of evolution and diversification in this group using the tools available from the model organism for genomics and genetics of the brown macroalgae.
Figure from Leliaert and De Clerck[1] (2017). Ectocarpus sp. strain NZKU 1–3 (CCAP 1310/56) in culture (photo by Olivier De Clerck), and cox1 phylogenetic tree of the Ectocarpus sub- group siliculosi showing the 15 DNA-delimited species by Montecinos[2] et al. (2017).
[1] Leliaert F, De Clerck O (2017) Refining species boundaries in algae. Journal of Phycology53, 12-16.
[2] Montecinos AE, Couceiro L, Peters AF, et al. (2017) Species delimitation and phylogeographic analyses in the Ectocarpus subgroup siliculosi (Ectocarpales, Phaeophyceae). Journal of Phycology53, 17-31.
A biophysical model based on the poro-elastic properties of the cells of the filamentous brown alga Ectocarpus is described, which allows to simulate cell shape changes and subsequent filament branching during the algal growth. This shows that mechanical factors only can account for the major developmental processes as observed in vivo in this organism.
Artificial selection is crucial to algal aquaculture development, and contrarily to many terrestrial plant species, selection process in seaweed is in infancy, particularly in Europe. The aim of the GENIALG project is to implement basic research for selection process in seaweed aquaculture incorporating rigorous evolutionary thinking into it. Generally, seaweed populations are characterized by large level of genetic differentiation suggesting that populations are adapted to their local environment. In this context, parents that are too similar genetically may suffer from reduced crossing compatibility due to inbreeding depression, whereas crosses between parents that are too different genetically may lead to an outbreeding depression by disrupting adaptive complexes. An intermediate optimal outcrossing distance is therefore expected as a compromise between inbreeding depression and outbreeding depression. In addition, seaweeds display complex life cycles, involving an alternation of haploid and diploid individuals. The consequences of such cycles for the reproductive system have been little studied experimentally. In particular, inbreeding depression is expected to be reduced as deleterious mutations are removed from the genome during the haploid phase.
The objective of this project is to address these questions combining crossing experiments with genetic analyses, in particular quantitative trait locus (QTL) and genome-wide association studies (GWAS) in the kelp Saccharina latissima. The effects of crosses on reproductive success will be investigated by examining the evolution of crossing compatibility with increasing geographic distance. The number of fertilizations and abortion rate will be measured in single-male crosses in laboratory conditions, as estimates of prezygotic and early postzygotic compatibility between mates. Segregating families will be generated by carrying out intraspecific crosses between selected strains of S. latissima and the progeny will be phenotyped under controlled conditions to identify novel strains with characteristics of industrial interest. Several parameters will be taken into account, including growth characteristics, biomolecule content (e.g. lipids, polysaccharides, proteins, amino acids) and stress and disease resistance. In addition to the phenotype-based breeding approaches proposed above, we will develop marker-based breeding strategies based on QTL identification and genome wide association studies (GWAS). These approaches will be developed specifically for S. latissima using data generated in the GENIALG project but will also take advantage of currently available genomic sequence data for this species and the sister species S. japonica (Yeet al., 2015, Nature communications, 6), and of additional genomic data that will be generated by the recently funded French "Phaeoexplorer" project.
Applicants must have a PhD in evolutionary ecology, in plant breeding or genetics. They must have a good background in population genetics and demonstrable experience in breeding experiments. Specific experience on seaweed ecology and culturing is preferable.
Salary will be 2000 € to 2500€ per month (net) depending on experience.
Applications are accepted until 10 May, 2017 and should include CV together with a description of research experience, relevant publications and 2 letters of references. Selected candidates will be interviewed from the 11 – 12 May 2017.
Applications should be sent to Myriam Valero ('; // -->) and Barbara Raffenne (barbara.raffenne@sb-roscoff.fr). We prefer applications in electronic form.
For more information please contact Myriam Valero.
The successful candidate will conduct research leading to the development of a genetic transformation protocol for the brown algal model Ectocarpus. Experience with molecular and cell biology techniques is essential. Experience with Agrobacterium-mediated plant transformation and algal manipulation would also be useful. Excellent written and oral communication skills and the ability to participate in writing reports and manuscripts are required.
Required Skills:
- MS in Biology, Molecular Biology, Biotechnology, Plant Science or related area preferred (other degrees could be considered depending on skills);
- Technical proficiency, scientific creativity, and ability to collaborate with others;
- Ability to work and think independently;
- Experience in DNA and RNA extraction, molecular analysis of transgenic organisms; transgenesis protocols; RNA interference
- Statistical data collection and interpretation;
- Excellent time management skills
Initial appointment is for 12 months and could be renewed depending on satisfactory performance and funding availability. Interested applicants should send via email a cover letter describing previous experience, CV, and names, telephone numbers and e-mail addresses of three references to coelho@sb-roscoff.fr and cock@sb-roscoff.fr.
Algae are (mostly) photosynthetic eukaryotes that occupy multiple branches of the tree of life, and are vital for planet function and health. This review highlights a transformative period in studies of the evolution and functioning of this extraordinary group of organisms and their potential for novel applications, wrought by high-throughput ‘omic’ and reverse genetic methods. It covers the origin and diversification of algal groups, explores advances in understanding the link between phenotype and genotype, considers algal sex determination, and reviews progress in understanding the roots of algal multicellularity. Experimental evolution studies to determine how algae evolve in changing environments are highlighted, as is their potential as production platforms for compounds of commercial interest such as biofuel precursors, nutraceuticals, or therapeutics.
The objective of this thesis project is to better understand the ecological and evolutionary role of local adaptation in three species of kelps.
These brown algae form large marine forests along temperate coasts and are one of the most productive marine ecosystems in the world. The importance of local adaptation along their range distribution will be measured by combining population genetics and genomics approaches with experimental approaches measuring response to abiotic stresses such as temperature.
In order to estimate the evolution of these populations, we will study the spatial and temporal variation of genetic diversity and life history traits (reproductive system, lifetime and age of reproduction) as complementary approaches conducted in the laboratory. In the context of kelp cultivation projects, the thesis will also use knowledge on the processes of local adaptation in order to propose genetic improvement strategies adapted to the ecoregions where the cultivated species will develop ( selection of local varieties) while aiming at maintaining the functioning of these ecosystems in the long term.
Sulfated biomolecules are widespread in Nature and highly diverse in chemical structure and biological function. For instance steroid sulfate, cerebroside sulfate or heparin play vital roles in human and animals. Plants produce numerous sulfated secondary metabolites acting as defense or communication molecules. Sulfated biomolecules are also ubiquitous in marine environment. Indeed all marine animals, plants and algae synthesize sulfated polysaccharides as major compounds of their extracellular matrix.
Sulfatases catalyze the cleavage of sulfate groups from such molecules and are thus essential enzymes in the biomedical field, but also in general biology, in environmental processes and in biotechnology. These proteins have been essentially studied in the context of severe genetic diseases in human and the number of characterized sulfatases is thus limited in comparison to the huge diversity of sulfated compounds. In the context of the explosion of genomic data, the prediction of the function of new sulfatases is therefore particularly prone to misinterpretations. A classification system allowing a better prediction of substrate specificity and for setting the limit of functional annotations is therefore urgently needed for sulfatases.
To answer this issue the Marine Glycobiology group, in close collaboration with the bioinformatics platform ABIMS, has created a general database, SulfAtlas, to classify all available sulfatases based on sequence homology. The details of this collaborative work has been published in the journal PLOS One the 17th of October 2016 ( http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164846). The SulfAtlas database will be regularly updated and is in free access at the following address: http://abims.sb-roscoff.fr/sulfatlas/.
Reference: Tristan BARBEYRON, Loraine BRILLET-GUÉGUEN, Wilfrid CARRÉ, Cathelène CARRIÈRE, Christophe CARON, Mirjam CZJZEK, Mark HOEBEKE and Gurvan MICHEL. (2016) Matching the diversity of sulfated biomolecules: creation of a classification database for sulfatases reflecting their substrate specificity (2016) PLOS One, 11:e0164846
In this review we bridge two distinct aspects of cell wall components from brown algae: the recent progress in term of cell wall architecture and the potential therapeutic usages of the fucose-containing sulfated polysaccharides extracted from these walls. We further assess the key remaining challenges to be addressed in these research fields.
Sulfated biomolecules are widespread in Nature and highly diverse in chemical structure and biological function. For instance steroid sulfate, cerebroside sulfate or heparin play vital roles in human and animals. Plants produce numerous sulfated secondary metabolites acting as defense or communication molecules. Sulfated biomolecules are also ubiquitous in marine environment. Indeed all marine animals, plants and algae synthesize sulfated polysaccharides as major compounds of their extracellular matrix.
Sulfatases catalyze the cleavage of sulfate groups from such molecules and are thus essential enzymes in the biomedical field, but also in general biology, in environmental processes and in biotechnology. These proteins have been essentially studied in the context of severe genetic diseases in human and the number of characterized sulfatases is thus limited in comparison to the huge diversity of sulfated compounds. In the context of the explosion of genomic data, the prediction of the function of new sulfatases is therefore particularly prone to misinterpretations. A classification system allowing a better prediction of substrate specificity and for setting the limit of functional annotations is therefore urgently needed for sulfatases.
To answer this issue the Marine Glycobiology group, in close collaboration with the bioinformatics platform ABIMS, has created a general database, SulfAtlas, to classify all available sulfatases based on sequence homology. The details of this collaborative work has been published in the journal PLOS One the 17th of October 2016 ( http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164846). The SulfAtlas database will be regularly updated and is in free access at the following address: http://abims.sb-roscoff.fr/sulfatlas/.
Reference: Tristan BARBEYRON, Loraine BRILLET-GUÉGUEN, Wilfrid CARRÉ, Cathelène CARRIÈRE, Christophe CARON, Mirjam CZJZEK, Mark HOEBEKE and Gurvan MICHEL. (2016) Matching the diversity of sulfated biomolecules: creation of a classification database for sulfatases reflecting their substrate specificity (2016) PLOS One, 11:e0164846
Carrageenans are the major component of the cell wall of red macroalgae. These sulfated polysaccharides have been widely used for over 70 years in various industries for their gelling and texturizing properties. Carrageenans and their derived oligosaccharides have promising potential as bioactives (antiviral, anticoagulant, immunomodulator, etc.). Ecologically, these polymers are an enormous source of nutrients in coastal ecosystems, particularly for heterotrophic marine bacteria that are key players in the recycling of organic matter in the oceans; however, the mechanisms of microbial degradation of algal polysaccharides remain largely unknown.
In this context, an international consortium, coordinated by the Marine Glycobiology team (UMR 8227) and involving teams from INRA, Génoscope-CEA, and an American and Australian team, have just published the discovery of the complete catabolic pathway of carrageenan in the marine model bacterium Zobellia galactanivorans. Through a combination of biochemical, crystallographic, transcriptomic, genetic and bioinformatic approaches, this complex biological system has been characterized on an unprecedented integrative level in marine biology. The functions of no less than 17 new proteins were thus resolved during this Homeric work. This article also made it possible to amend the notion of a "Polysaccharide Utilization Locus" (PUL). This last result has a general scope, the study of PULs becoming a hot topic in recent years in understanding the host-pathogen interaction in plants and within the biomedical field.
Référence
Ficko-Blean E, Préchoux A, Thomas F, Rochat T, Larocque R, Zhu Y, Stam M, Génicot S, Jam M, Calteau A, Viart B, Ropartz D, Perez-Pascual D, Correc G, Matard M, Stubbs KA, Rogniaux H, Jeudy A, Barbeyron T, Médigue C, Czjzek M, Vallenet D, McBride MJ, Duchaud E, & Michel G (2017) Carrageenan catabolism is encoded by a complex regulon in marine heterotrophic bacteria. Nature Communications, 8, 1685. doi:10.1038/s41467-017-01832-6
Gurvan MICHEL, Tel : 02 98 29 23 30 ; email : gurvan.michel@sb-roscoff.fr
Article in Nature Communications : https://www.nature.com/articles/s41467-017-01832-6
Comments in Nature Microbiology : (« behind the paper ») : https://naturemicrobiologycommunity.nature.com/users/68108-elizabeth-ficko-blean/posts/22214-perseverance-pays-off
Brown algae are multicellular photosynthetic marine organisms living on rocky shores across the globe and representing one of the most developmentally complex groups within the eukaryotes. As in many land plants and animals, their main body axis is established early in development, when the initial cell gives rise to two daughter cells that have apical (‘stipe’) and basal (‘holdfast’) identities, equivalent to ‘shoot’ and ‘root’ identities in land plants, respectively. The establishment of the apical-basal axis in the model land plant Arabidopsis is controlled by a complex genetic network that is well characterized, but we have remained surprisingly ignorant about the mechanisms and genetic systems that underlie apical-basal axis formation in the brown algae.
We wanted to find out how, from a single cell released in the ocean, brown algae initiate the development of their basal system. What are the gene(s) and mechanisms involved in building a seaweed holdfast?
We used Ectocarpus, a small filamentous brown alga amenable to laboratory techniques, and a range of genetic, cell biology and genomic approaches to identify and characterize a gene (DISTAG/TBCCd1) that controls the position of organelles inside the first cell of the alga, and is required for the initiation of the basal system in this organism. distag mutants therefore allowed us to link subcellular events within the initial cell with apical-basal axis formation and the acquisition of cell identities in Ectocarpus. TBCCd1 proteins are involved in cellular patterning in plants and animals, so our study has also emphasized the remarkable functional conservation of TBCCd1 proteins in regulating internal cell organization across a billion years of eukaryotic evolution.
Further work is required to understand the exact cellular role of TBCCd1 in Ectocarpus and other brown alga, and to uncover the detailed mechanisms involved in establishing the basal system identity in these organisms. A comparative analysis of the pathways involved in cell fate determination in brown algae, green plants and animals would give a fascinating view on how developmental processes are conserved, or not, across different multicellular organisms.
1 Sorbonne University, Evry Val-d'Essonne University, Paris-Saclay University
A global ocean atlas of eukaryotic genes, Quentin Carradec, Eric Pelletier§, Corinne Da Silva, Adriana Alberti, Yoann Seeleuthner, Romain Blanc-Mathieu, Gipsi Lima-Mendez, Fabio Rocha, Leila Tirichine, Karine Labadie, Amos Kirilovsky, Alexis Bertrand, Stefan Engelen, Mohammed-Amin Madoui, Raphaël Méheust, Julie Poulain, Sarah Romac, Daniel J. Richter, Genki Yoshikawa, Céline Dimier, Stefanie Kandels-Lewis, Marc Picheral, Sarah Searson, Tara Oceans Coordinators, Olivier Jaillon, Jean-Marc Aury, Eric Karsenti, Matthew B. Sullivan, Shinichi Sunagawa, Peer Bork, Fabrice Not, Pascal Hingamp, Jeroen Raes, Lionel Guidi, Hiroyuki Ogata, Colomban de Vargas, Daniele Iudicone, Chris Bowler§, Patrick Wincker§ (§ : corresponding authors), Nature Communications, 25 janvier 2018.
Single-cell genomics of multiple uncultured stramenopiles reveals underestimated functional diversity across oceans, Yoann Seeleuthner, Samuel Mondy, Vincent Lombard, Quentin Carradec, Eric Pelletier, Marc Wessner, Jade Leconte, Jean-François Mangot, Julie Poulain, Karine Labadie, Ramiro Logares, Shinichi Sunagawa, Véronique de Berardinis, Marcel Salanoubat, Céline Dimier, Stefanie Kandels-Lewis, Marc Picheral, Sarah Searson, Tara Oceans Coordinators, Stephane Pesant, Nicole Poulton, Ramunas Stepanauskas, Peer Bork, Chris Bowler, Pascal Hingam, Matthew B. Sullivan, Daniele Iudicone, Ramon Massana, Jean-Marc Aury, Bernard Henrissat, Eric Karsenti, Olivier Jaillon, Mike Sieracki§, Colomban de Vargas§, Patrick Wincker§ (§ Corresponding authors), doi:10.1038/s41467-017-02235-3, Nature Communications, 22 janvier 2018
Colomban de Vargas, c2vargas@gmail.com
Research Unit : UMR 8227: Laboratory of Integrative biology of Marine Models
Location: Station Biologique de Roscoff (on the north coast of Brittany, FRANCE)
Function: Structural investigation of RNA : protein interactions
Salary: 2900 €/month (approx.). The grant (SAD) is issued by The Region of Brittany.
The candidate must have worked 12 months (at least) between June 2014 and May 2017 outside France.
Dr. Anne-Catherine Dock-Bregeon: acdockbregeon@sb-roscoff.fr
+33 (0)298 292 332
Station Biologique de Roscoff Place Georges Teissier 29680 ROSCOFF FRANCE
Registration for summer schools is extended until March 25, 2018.