ArticleProceedings of the National Academy of Sciences of the United States of America2006
Complete nucleotide sequence of the chlorarachniophyte nucleomorph: nature's smallest nucleus.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2006. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 85 papers.
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85 citing papers in PubMed, 208 citations in OpenAlex.
- Strain-level diversity of giant viruses infecting chlorarachniophyte algae in the subtropical North Pacific.The ISME journal · 2026Article
- Nuclear genome sequencing reveals the highly intron-rich architecture of the chlorarachniophyte alga Amorphochlora amoebiformis.DNA research : an international journal for rapid publication of reports on genes and genomes · 2025Article
- Pan-microalgal dark proteome mapping via interpretable deep learning and synthetic chimeras.Patterns (New York, N.Y.) · 2025Article
- How to upgrade stolen organelles into permanent plastids: A comparative transcriptomic perspective.Proceedings of the National Academy of Sciences of the United States of America · 2025Article
- Redefining the spliceosomal introns of the sexually transmitted parasite Trichomonas vaginalis and its close relative in columbid birds.PLoS pathogens · 2025Article
- The complete mitochondrial genome assembly of Capsicum pubescens reveals key evolutionary characteristics of mitochondrial genes of two Capsicum subspecies.BMC genomics · 2024Article
- Decryption of the survival "black box": gene family expansion promotes the encystment in ciliated protists.BMC genomics · 2024Article
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- The chromatin organization of a chlorarachniophyte nucleomorph genome.Genome biology · 2022Article
- Lipid Droplets in Unicellular Photosynthetic Stramenopiles.Frontiers in plant science · 2021Review
- Changes in the transcriptome, ploidy, and optimal light intensity of a cryptomonad upon integration into a kleptoplastic dinoflagellate.The ISME journal · 2020Article
- Dinoflagellates with relic endosymbiont nuclei as models for elucidating organellogenesis.Proceedings of the National Academy of Sciences of the United States of America · 2020Article
- Patterns of conservation of spliceosomal intron structures and spliceosome divergence in representatives of the diplomonad and parabasalid lineages.BMC evolutionary biology · 2019Article
- The Known, the New, and a Possible Surprise: A Re-Evaluation of the Nucleomorph-Encoded Proteome of Cryptophytes.Genome biology and evolution · 2019Article
- Relative Mutation Rates in Nucleomorph-Bearing Algae.Genome biology and evolution · 2019Article
- Nucleomorph Small RNAs in Cryptophyte and Chlorarachniophyte Algae.Genome biology and evolution · 2019Article
- Extensive Reduction of the Nuclear Pore Complex in Nucleomorphs.Genome biology and evolution · 2019Article
- Iron-Sulfur Cluster Biosynthesis in Algae with Complex Plastids.Genome biology and evolution · 2018Article
25 more citing papers are in PubMed but not listed here.
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Authors and funding
6 authors at 4 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The introduction of plastids into different heterotrophic protists created lineages of algae that diversified explosively, proliferated in marine and freshwater environments, and radically altered the biosphere. The origins of these secondary plastids are usually inferred from the presence of additional plastid membranes. However, two examples provide unique snapshots of secondary-endosymbiosis-in-action, because they retain a vestige of the endosymbiont nucleus known as the nucleomorph. These are chlorarachniophytes and cryptomonads, which acquired their plastids from a green and red alga respectively. To allow comparisons between them, we have sequenced the nucleomorph genome from the chlorarachniophyte Bigelowiella natans: at a mere 373,000 bp and with only 331 genes, the smallest nuclear genome known and a model for extreme reduction. The genome is eukaryotic in nature, with three linear chromosomes containing densely packed genes with numerous overlaps. The genome is replete with 852 introns, but these are the smallest introns known, being only 18, 19, 20, or 21 nt in length. These pygmy introns are shown to be miniaturized versions of normal-sized introns present in the endosymbiont at the time of capture. Seventeen nucleomorph genes encode proteins that function in the plastid. The other nucleomorph genes are housekeeping entities, presumably underpinning maintenance and expression of these plastid proteins. Chlorarachniophyte plastids are thus serviced by three different genomes (plastid, nucleomorph, and host nucleus) requiring remarkable coordination and targeting. Although originating by two independent endosymbioses, chlorarachniophyte and cryptomonad nucleomorph genomes have converged upon remarkably similar architectures but differ in many molecular details that reflect two distinct trajectories to hypercompaction and reduction.
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