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A photosynthetic alveolate closely related to apicomplexan parasites

A Corrigendum to this article was published on 17 April 2008


Many parasitic Apicomplexa, such as Plasmodium falciparum, contain an unpigmented chloroplast remnant termed the apicoplast, which is a target for malaria treatment. However, no close relative of apicomplexans with a functional photosynthetic plastid has yet been described. Here we describe a newly cultured organism that has ultrastructural features typical for alveolates, is phylogenetically related to apicomplexans, and contains a photosynthetic plastid. The plastid is surrounded by four membranes, is pigmented by chlorophyll a, and uses the codon UGA to encode tryptophan in the psbA gene. This genetic feature has been found only in coccidian apicoplasts and various mitochondria. The UGA-Trp codon and phylogenies of plastid and nuclear ribosomal RNA genes indicate that the organism is the closest known photosynthetic relative to apicomplexan parasites and that its plastid shares an origin with the apicoplasts. The discovery of this organism provides a powerful model with which to study the evolution of parasitism in Apicomplexa.

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Figure 1: Ultrastructure of new alveolate Chromera velia.
Figure 2: Nuclear and plastid phylogenies of Chromera velia.
Figure 3: Evolution of Chromera velia , apicomplexans and dinoflagellates.


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This work was supported by an ARC grant to D.A.C. and O.H.-G.; an ABRS grant to D.A.C.; grants from the Czech Science Foundation, Academy of Sciences of the Czech Republic and Czech Ministry of Education to M.O.; University of Iowa start-up funds and an NSF grant to J.M.L.; and a University of Tasmania Institutional Research grant to C.J.S.B. We thank A. McMinn for pulse amplitude modulation data, A. Simpson for analytical suggestions, R. Andersen for culture backup, and A. Polaszek and M. Garland for taxonomic opinions.

Author Contributions R.B.M. isolated the strain while in the D.A.C. laboratory, then while in the J.M.L. laboratory designed the AToL SSU primers and the psbA primers, cloned and sequenced multiple copies of the SSU rRNA gene, a copy of the plastid SSU rRNA gene and initial sections of the psbA and LSU rRNA genes, then assigned precedented methods for culture fixation, and wrote and finalized the draft of the paper; M.O. led and performed phylogenetic analyses of the sequence data, cloned and sequenced a copy of the plastid SSU rDNA gene using different primers than R.B.M., and co-wrote the draft of the paper; M.O. and M.V. performed the TEM and SEM data collection; J.J. and T.C. cloned and sequenced near full-length LSU rDNA and psbA genes and undertook extensive phylogenetic analysis; T.C. performed mito-red staining; S.W.W. and N.W.D. performed pigment analysis and interpreted pigment data; R.B.M., K.H., C.J.S.B. and J.S. interpreted TEM data and assigned taxonomy; K.H. and R.B.M. performed light microscopy; R.B.M., M.O., T.C., K.H., D.H.G. and C.J.S.B. maintained cultures. D.H.G. cloned and sequenced the LSU rRNA gene, using different PCR primers than T.C. and J.J.; R.B.M., M.O., D.H.G., K.H., J.S., O.H.-G., J.M.L., C.J.S.B. and D.A.C. designed research, interpreted evolutionary, ecological and microbiological data, and performed extensive editing and revision.

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Correspondence to Dee A. Carter.

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The file contains Supplementary Notes with additional references, Supplementary Tables S1-S3 and Supplementary Figures S1-S22 with Legends. (PDF 3207 kb)

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Moore, R., Oborník, M., Janouškovec, J. et al. A photosynthetic alveolate closely related to apicomplexan parasites. Nature 451, 959–963 (2008).

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