Dinoflagellate

Habitat

Dinoflagellates are a large family of single celled algae that occupy many habitats in both fresh and marine waters. Some dinoflagellates are endosymbionts, living inside host organisms, but with no harm to them. The dinoflagellate Symbiodinium is the dominant genus of algal symbiont in reef-building corals and in many other invertebrates in the world's oceans. Reef-building corals have an obligatory requirement for intracellular Symbiodinium, to provide photosynthesis, which fuels the energetically expensive deposition of calcium carbonate.

Biology

Symbiodinium is very important both ecologically and economically, and Symbiodinium even makes toxins related to the toxins made by red-tide causing dinoflagellates, although no one yet knows why. Reef-building corals have an obligatory requirement for intracellular Symbiodinium, to provide photosynthesis, which fuels the energetically expensive deposition of calcium carbonate. Essentially, corals make their living farming dinoflagellates. Corals deprived of this type of organism deposit far less calcium carbonate and do not build the reefs that currently dominate coastlines in many parts of the world. These reefs function to house an estimated biodiversity of 1-9 million species, directly support an estimated 100 million people worldwide, underpin major industries and national earnings, and protect coastlines and other coastal habitats. Symbiodinium is also a point of vulnerability to coral reefs. When corals are stressed by environmental perturbations such as declining water quality or climate change, the symbiotic relationship between host and dinoflagellate symbiont breaks down. The reasons for this symbiotic dysfunction, termed coral bleaching, are poorly understood, but this is predicted to reach a point where whole reefs disappear worldwide.

More practically, while dinoflagellates all have very large genomes-some are many times larger than the human genome - Symbiodinium has the smallest one so far known.

Dinoflagellates are a sister group to the apicomplexans - important human and animal pathogens, e.g. Plasmodium, the cause of malaria. Symbiotic dinoflagellates and parasitic apicomplexa have in common the ability to reside in host cells for long periods. Since dinoflagellates are a sister group to the exclusively parasitic apicomplexans, much might be learned by comparing the intracellular adaptations of apicomplexans with those of symbiotic dinoflagellates, helping us to understand the capacities, weaknesses and evolution of the apicomplexans.

-- From Dr. Tom Doak, Princeton Univeristy

TOP

Contacts

Name	Affiliation
Patrick Minx	The Genome Institute, Washington University School of Medicine
Tom Doak	Department of Ecology and Evolutinoary Biology, Princeton University
Laura Landweber	Department of Ecology and Evolutinoary Biology, Princeton University

TOP