masion
(2022-02-28 22:39):
#paper doi.org/10.1038/nature11681 Nature volume 492, pages59–65 (2012)，Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
通过对以吞没某些真核藻类而获得光合作用的内共生体中的过渡形式吉氏藻Guillardia theta和纳氏毕氏藻Bigelowiella natans的核基因组进行测序，揭示了单细胞生物体（纳氏毕氏藻）前所未有的选择性剪接以及广泛的遗传和生化镶嵌现象，揭示了为什么会在这些物种中存在，而不存在于其他藻类中。
Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
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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.
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