Going, going, not quite gone: nucleomorphs as a case study in nuclear genome reduction.

Full Abstract

Nucleomorphs are the relic nuclei of algal endosymbionts that became permanent fixtures inside nonphotosynthetic eukaryotic host cells. These unusual organelles exist in only 2 lineages, the cryptophytes, which possess nucleomorphs and plastids (chloroplasts) derived from the uptake of a red algal endosymbiont, and the chlorarachniophytes, which harbor green algal derived nucleomorphs and plastids. Despite having evolved independently of one another, the nucleomorph genomes of cryptophytes and chlorarachniophytes are strikingly similar in size and basic structure. Both are <1 Mbp in size-the smallest nuclear genomes known-and are composed of only 3 chromosomes, each with its own subtelomeric rDNA repeats. Nucleomorph-containing algae thus represent an interesting system in which to study genome and chromosome evolution in eukaryotes. Here, we provide an overview of nucleomorph genome biology and focus on new information gleaned from comparisons of complete nucleomorph genome sequences, both within and between cryptophytes and chlorarachniophytes. Such comparisons provide fascinating insight into the evolution of these highly derived organelles and, more generally, the potential causes and consequences of genome reduction in eukaryotes.

Author information

Author/s: Archibald, John M (JM); Lane, Christopher E (CE);

Affiliation: Canadian Institute for Advanced Research, Integrated Microbial Biodiversity Program, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada. john.archibald(-atsign-)dal.ca

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Review

Journal: The Journal of heredity (J Hered), published in United States. (Language: eng)

Reference: -2009 Sep-Oct; vol 100 (issue 5) : pp 582-90

Dates: Created 2009/08/18; Completed 2009/10/16;

PMID: 19617523, status: MEDLINE (last retrieval date: 10/16/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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