Eye-like ocelloids are built from different endosymbiotically acquired components
AuthorsGavelis, Gregory S.
White, Richard A.
Suttle, Curtis A.
Keeling, Patrick J.
Leander, Brian S.
KAUST DepartmentComputational Bioscience Research Center (CBRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Online Publication Date2015-07-01
Print Publication Date2015-07
Permanent link to this recordhttp://hdl.handle.net/10754/566109
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AbstractMulticellularity is often considered a prerequisite for morphological complexity, as seen in the camera-type eyes found in several groups of animals. A notable exception exists in single-celled eukaryotes called dinoflagellates, some of which have an eye-like 'ocelloid' consisting of subcellular analogues to a cornea, lens, iris, and retina. These planktonic cells are uncultivated and rarely encountered in environmental samples, obscuring the function and evolutionary origin of the ocelloid. Here we show, using a combination of electron microscopy, tomography, isolated-organelle genomics, and single-cell genomics, that ocelloids are built from pre-existing organelles, including a cornea-like layer made of mitochondria and a retinal body made of anastomosing plastids. We find that the retinal body forms the central core of a network of peridinin-type plastids, which in dinoflagellates and their relatives originated through an ancient endosymbiosis with a red alga. As such, the ocelloid is a chimaeric structure, incorporating organelles with different endosymbiotic histories. The anatomical complexity of single-celled organisms may be limited by the components available for differentiation, but the ocelloid shows that pre-existing organelles can be assembled into a structure so complex that it was initially mistaken for a multicellular eye. Although mitochondria and plastids are acknowledged chiefly for their metabolic roles, they can also be building blocks for greater structural complexity.
- Function and evolutionary origin of unicellular camera-type eye structure.
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- Molecular phylogeny of ocelloid-bearing dinoflagellates (Warnowiaceae) as inferred from SSU and LSU rDNA sequences.
- Authors: Hoppenrath M, Bachvaroff TR, Handy SM, Delwiche CF, Leander BS
- Issue date: 2009 May 25
- Mitochondrial genome of a tertiary endosymbiont retains genes for electron transport proteins.
- Authors: Imanian B, Carpenter KJ, Keeling PJ
- Issue date: 2007 Mar-Apr
- Integration of plastids with their hosts: Lessons learned from dinoflagellates.
- Authors: Dorrell RG, Howe CJ
- Issue date: 2015 Aug 18
- An assessment of vertical inheritance versus endosymbiont transfer of nucleus-encoded genes for mitochondrial proteins following tertiary endosymbiosis in Karlodinium micrum.
- Authors: Danne JC, Gornik SG, Waller RF
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