Abstract
BackgroundPhotosynthetic euglenids are major contributors to fresh water ecosystems. Euglena gracilis in particular has noted metabolic flexibility, reflected by an ability to thrive in a range of harsh environments. E. gracilis has been a popular model organism and of considerable biotechnological interest, but the absence of a gene catalogue has hampered both basic research and translational efforts.ResultsWe report a detailed transcriptome and partial genome for E. gracilis Z1. The nuclear genome is estimated to be around 500 Mb in size, and the transcriptome encodes over 36,000 proteins and the genome possesses less than 1% coding sequence. Annotation of coding sequences indicates a highly sophisticated endomembrane system, RNA processing mechanisms and nuclear genome contributions from several photosynthetic lineages. Multiple gene families, including likely signal transduction components, have been massively expanded. Alterations in protein abundance are controlled post-transcriptionally between light and dark conditions, surprisingly similar to trypanosomatids.ConclusionsOur data provide evidence that a range of photosynthetic eukaryotes contributed to the Euglena nuclear genome, evidence in support of the ‘shopping bag’ hypothesis for plastid acquisition. We also suggest that euglenids possess unique regulatory mechanisms for achieving extreme adaptability, through mechanisms of paralog expansion and gene acquisition.
Highlights
IntroductionA photosynthetic flagellate, was first described by van Leeuwenhoek in 1684 [1]
Euglena gracilis, a photosynthetic flagellate, was first described by van Leeuwenhoek in 1684 [1]
These data were assembled as described in methods and as previously [48] and latterly supplemented with PacBio data generously donated by colleagues (Purificatión Lopéz-García, David Moreira and Peter Myler, with thanks)
Summary
A photosynthetic flagellate, was first described by van Leeuwenhoek in 1684 [1]. E. gracilis is of importance due to evolutionary history, divergent cellular architecture, complex metabolism and biology, together with considerable potential for biotechnological exploitation [17]. The full complexity of euglenid biology remains to be revealed, and the absence of a complete genome sequence or annotated transcriptome has greatly hampered efforts to Ebenezer et al BMC Biology (2019) 17:11 study E. gracilis or to develop genetic tools [17, 18]. Euglena gracilis in particular has noted metabolic flexibility, reflected by an ability to thrive in a range of harsh environments. E. gracilis has been a popular model organism and of considerable biotechnological interest, but the absence of a gene catalogue has hampered both basic research and translational efforts
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