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Title: A multi-omic analysis of the photosynthetic endosymbioses of Paramecium bursaria
Author: Maguire, F.
ISNI:       0000 0004 8497 6763
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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The photosynthetic endosymbioses between Paramecium bursaria and its green algal endosymbionts (Chlorella variabilis, Chlorella vulgaris, Micractinium reisseri and Coccomyxa sp.) have long been suggested to represent nascent endosymbiotic interactions as host and endosymbiont are believed to be able to exist and reproduce separately. Understanding the molecular systems underpinning these relationships would therefore provide a model system to investigate the process of photosynthetic endosymbioses before molecular co-dependence has become fixed (leading to genomic integration). To this end, the metatranscriptome of P. bursaria-M. reisseri during lit and dark conditions was recovered using single cell methods. This necessitated the development of novel techniques to optimise the assembly and the post-assembly attribution of transcripts to their originating organism. This work represents the first de novo single cell transcriptomic analysis of a multi-member eukaryotic system. Metabolicfunctionwasthen analysed inthis system using bothtranscriptomic and metabolomics data. This identified potential roles for novel sugar, amino acid, and fatty acid interactions in the M. reisseri endosymbiosis. Additionally, P. bursaria SW1 was determined to potentially form a obligate host of M. reisseri SW1-ZK. Finally, this work also revealed a putative non-functional exogenous RNA induced RNAi system in P. bursaria potentially related to the absence of a factor associated with uptake of RNA from host vacuoles in both P. bursaria transcriptomes and a partial P. bursaria single cell genome. An analysis of the level of potential RNAi "cross-talk" collisions with the active host transcriptome suggests that the function of an exogenous RNA induced RNAi system in the presence of a eukaryotic endosymbiont may be deleterious. Therefore, despite discovering several barriers to the utility of these systems for studying endosymbiotic evolution there is still benefit to their study. The "omic" resources and analyses presented here offer an important dataset to inform further analysis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available