Comparison of gene expression of Paramecium bursaria with and without Chlorella variabilissymbionts

Abstract

BackgroundThe ciliate Paramecium bursaria harbors several hundred cells of the green-alga Chlorella sp. in their cytoplasm. Irrespective of the mutual relation between P. bursaria and the symbiotic algae, both cells retain the ability to grow without the partner. They can easily reestablish endosymbiosis when put in contact with each other. Consequently, P. bursaria is an excellent model for studying cell–cell interaction and the evolution of eukaryotic cells through secondary endosymbiosis between different protists. Despite the importance of this organism, no genomic resources have been identified for P. bursaria to date. This investigation compared gene expressions through RNA-Seq analysis and de novo transcriptome assembly of symbiont-free and symbiont-bearing host cells.ResultsTo expedite the process of gene discovery related to the endosymbiosis, we have undertaken Illumina deep sequencing of mRNAs prepared from symbiont-bearing and symbiont-free P. bursaria cells. We assembled the reads de novo to build the transcriptome. Sequencing using Illumina HiSeq2000 platform yielded 232.3 million paired-end sequence reads. Clean reads filtered from the raw reads were assembled into 68,175 contig sequences. Of these, 10,557 representative sequences were retained after removing Chlorella sequences and lowly expressed sequences. Nearly 90% of these transcript sequences were annotated by similarity search against protein databases. We identified differentially expressed genes in the symbiont-bearing P. bursaria cells relative to the symbiont-free cells, including heat shock 70 kDa protein and glutathione S-transferase.ConclusionsThis is the first reported comprehensive sequence resource of Paramecium – Chlorella endosymbiosis. Results provide some keys for the elucidation of secondary endosymbiosis in P. bursaria. We identified P. bursaria genes that are differentially expressed in symbiont-bearing and symbiont-free conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-183) contains supplementary material, which is available to authorized users.

Symbiont modulates expression of specific gene categories in Angomonas deanei

“…2A-B). The influence of symbionts in host gene expression has been shown in other symbiotic associations (Lehnert et al 2012, 2014, Kodama et al 2014, Zhao et al 2014). Comparative transcriptional analysis performed in orchid Cymbidium hybridum in the presence or absence of the mycorrhizal fungus showed that the symbiont positively influences plant gene expression.…”

Fitness Impact of Obligate Intranuclear Bacterial Symbionts Depends on Host Growth Phase

“…Likely, the underlying molecular mechanism involves an increase of Paramecium heat-shock gene ( hsp ) expression caused by the symbiont (Hori and Fujishima, 2003). Enhanced hsp mRNA levels have also been observed for Paramecium bursaria living in symbiosis with the photosynthetic microalgae Chlorella (Kodama et al, 2014). If H. caryophila likewise effects the hsp expression of its host has not yet been studied.…”

Characterization of a new chlorovirus type with permissive and non-permissive features on phylogenetically related algal strains

“…Chlorovirus hosts, which are normally endosymbionts, are often referred to as zoochlorellae (Karakashian & Karakashian, 1965; Karakashian, 1975; Kodama et al, 2014). They are associated with either the protozoan Paramecium bursaria , the coelenterate Hydra viridis or the heliozoon Acanthocystis turfacea (Van Etten & Dunigan, 2012).…”