Euglena is a well-known and long-studied microbe, which has a reputation for being a ‘chimera’ of plant and animal and is still looking for home in taxonomy. In this study, by ‘sorting the wheat from the chaff’ using the super-computer, we illustrated that the Euglena genome was an evolutionary mosaic and that the common ancestor of euglenophyte algae and non-photosynthetic relatives could have had genes more similar to those from distantly related algae harboring the secondary plastid of ‘red’ algal origin (e.g. kelps, diatoms and many red-tide harmful algae) than green algae giving rise to the ‘green’ plastid which euglenophyte algae currently retain in the cells. The presence of these ‘laterally transferred’ genes in the genome suggests that the ancestor of Euglena might have had a ‘red’ tint at the genomic level, and perhaps also the cytological level, before getting ‘green’ via acquisition of secondary plastids from green algae.

Shinichiro Maruyama^1,2, Toshinobu Suzaki³, Andreas P. M. Weber⁴, John M. Archibald², Hisayoshi Nozaki¹

• ¹ Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
• ² The Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Department of Biochemistry and Molecular Biology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia, B3H 1X5, Canada.
• ³ Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan.
• ⁴ Institute for Plant Biochemistry, Heinrich-Heine-University, Geb. 26.03.01, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.

• Eukaryote-to-eukaryote gene transfer gives rise to genome mosaicism in euglenids
• BMC Evolutionary Biology 2011, 11:105
• doi:10.1186/1471-2148-11-105
• http://www.biomedcentral.com/1471-2148/11/105