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Jam packed genomes--a preliminary, comparative analysis of nucleomorphs
Paul R Gilson1, Geoffrey I McFadden
1Centre for Cellular and Molecular Biology, School of Biological and Chemical Sciences, Deakin University, VIC, Australia.
Genetica
|August 22, 2002
Summary
Eukaryotic cells acquire chloroplasts by engulfing algae, retaining a remnant nucleus called a nucleomorph. These compact nucleomorph genomes, like Guillardia theta
Area of Science:
- * Endosymbiosis and organelle genomics.
- * Eukaryotic cell evolution and plastid acquisition.
Background:
- * Eukaryotic cells can acquire chloroplasts through primary or secondary endosymbiosis.
- * Secondary endosymbiosis, engulfing an alga, is common, leading to diverse plastid-bearing protists.
- * Cryptomonads and chlorarachniophytes retain a remnant nucleus (nucleomorph) from the engulfed alga.
Purpose of the Study:
- * To compare the emerging similarities and differences between nucleomorph genomes.
- * To investigate the extreme compactness and rapid evolution of nucleomorph genes.
- * To understand the gene coding capacity and functional allocation within nucleomorphs.
Main Methods:
- * Comparative genomics of nucleomorph DNA.
- * Analysis of gene content and genome structure.
- * Sequencing of nucleomorph genomes from Guillardia theta and Bigellowiella natans.
Main Results:
- * Nucleomorph genomes are the smallest and most compact known eukaryotic genomes.
- * Both studied nucleomorphs possess three chromosomes encoding housekeeping and chloroplast-related genes.
- * Gene coding capacity is primarily dedicated to self-perpetuation and essential chloroplast protein production.
Conclusions:
- * Nucleomorphs represent highly reduced genomes resulting from secondary endosymbiosis.
- * Extreme compactness and rapid gene sequence evolution are key characteristics.
- * Understanding nucleomorphs provides insights into genome reduction and organelle evolution.