title: Transcriptome analyses to investigate symbiotic relationships between marine protists.
abstract: Rhizaria are an important component of oceanic plankton communities worldwide. A number of species harbor eukaryotic microalgal symbionts, which are horizontally acquired in the environment at each generation. Although these photosymbioses are determinant for Rhizaria ability to thrive in oceanic ecosystems, the mechanisms for symbiotic interactions are unclear. Using high-throughput sequencing technology (i.e., 454), we generated large Expressed Sequence Tag (EST) datasets from four uncultured Rhizaria, an acantharian (Amphilonche elongata), two polycystines (Collozoum sp. and Spongosphaera streptacantha), and one phaeodarian (Aulacantha scolymantha). We assessed the main genetic features of the host/symbionts consortium (i.e., the holobiont) transcriptomes and found rRNA sequences affiliated to a wide range of bacteria and protists in all samples, suggesting that diverse microbial communities are associated with the holobionts. A particular focus was then carried out to search for genes potentially involved in symbiotic processes such as the presence of c-type lectins-coding genes, which are proteins that play a role in cell recognition among eukaryotes. Unigenes coding putative c-type lectin domains (CTLD) were found in the species bearing photosynthetic symbionts (A. elongata, Collozoum sp., and S. streptacantha) but not in the non-symbiotic one (A. scolymantha). More particularly, phylogenetic analyses group CTLDs from A. elongata and Collozoum sp. on a distinct branch from S. streptacantha CTLDs, which contained carbohydrate-binding motifs typically observed in other marine photosymbiosis. Our data suggest that similarly to other well-known marine photosymbiosis involving metazoans, the interactions of glycans with c-type lectins is likely involved in modulation of the host/symbiont specific recognition in Radiolaria.
authors: UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France.
authors: Sergio
authors: S
authors: Balzano
authors: Centre National de la Recherche Scientifique and Université Pierre et Marie Curie, FR2424, ABiMS, Station Biologique Roscoff, France.
authors: Erwan
authors: E
authors: Corre
authors: UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France.
authors: Johan
authors: J
authors: Decelle
authors: Department of Genetics and Evolution, University of Geneva Geneva, Switzerland.
authors: Roberto
authors: R
authors: Sierra
authors: Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France.
authors: Patrick
authors: P
authors: Wincker
authors: Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France.
authors: Corinne
authors: C
authors: Da Silva
authors: Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France.
authors: Julie
authors: J
authors: Poulain
authors: Department of Genetics and Evolution, University of Geneva Geneva, Switzerland.
authors: Jan
authors: J
authors: Pawlowski
authors: UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France.
authors: Fabrice
authors: F
authors: Not
keywords: ESTs; Rhizaria; c-type lectins; photosymbiosis; plankton; radiolarian