Cell Biology of Chromerids: Autotrophic Relatives to Apicomplexan Parasites - International Review of Cell and Molecular Biology - page 328

CHAPTER EIGHT

Cell Biology of Chromerids:
Autotrophic Relatives to
Apicomplexan Parasites

,†
* Biology Centre, Institute of Parasitology, Academy of Sciences of the Czech Republic, ˇ esk´ Budˇjovice,
Czech Republic
† Faculty of Science, University of South Bohemia, ˇ esk´ Budˇjovice, Czech Republic
{ Institute of Microbiology, Academy of Sciences of the Czech Republic, Tˇeboˇ , Czech Republic
1 Corresponding author: e-mail address: [e-mail]

,†, { ,1 , Julius Luke š *

Miroslav Oborník *

Contents
1.

Introduction 334

2. Chromerida: A New Group of Algae Isolated from Australian Corals 337

2.1 C. velia: A new alga from Sydney Harbor 338

2.2 V. brassicaformis: An alga from the Great Barrier Reef 343

3. Life Cycle 346

4. Evolution of Exosymbiont 348

5. Evolution of Chromerid Organelles 350

5.1 Evolution of chromerid plastids 350

5.2 Reduced mitochondrial genomes of chromerids 354

5.3 Chromerosome: C. velia as a possible mixotroph 354

6. Metabolism of Chromerids 355

6.1 Unique pathway for tetrapyrrole biosynthesis 355

6.2 Other metabolic features of C. velia 359

7. Chromerids as Possible Symbionts of Corals 361

8. Conclusions 361

Acknowledgments 362

References 362

Abstract
Chromerida are algae possessing a complex plastid surrounded by four membranes.
Although isolated originally from stony corals in Australia, they seem to be globally dis-
tributed. According to their molecular phylogeny, morphology, ultrastructure, structure
of organellar genomes, and noncanonical pathway for tetrapyrrole synthesis, these
algae are thought to be the closest known phototrophic relatives to apicomplexan par-
asites. Here, we summarize the current knowledge of cell biology and evolution of this
novel group of algae, which contains only two formally described species, but is appar-
ently highly diverse and virtually ubiquitous in marine environments.