Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs.
Nature
; 492(7427): 59-65, 2012 Dec 06.
Article
in En
| MEDLINE
| ID: mdl-23201678
ABSTRACT
Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Symbiosis
/
Cell Nucleus
/
Genome
/
Evolution, Molecular
/
Cryptophyta
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Cercozoa
/
Mosaicism
Language:
En
Journal:
Nature
Year:
2012
Document type:
Article
Affiliation country: