Chromera velia
Encyclopedia
Chromera velia, also known as a "chromerid", is a photosynthetic alga in the superphylum Alveolata.
It has typical features of alveolates, being phylogenetically related to apicomplexa
, and contains a photosynthetic plastid
. C. velia uses this organelle as the primary energy source, thus being the closest known autotrophic organism to apicomplexans. It may retain a symbiotic relationship with the coral reef
around it.
) from the stony coral (Scleractinia
, Cnidaria
) Plesiastrea versipora (Faviidae
) of Sydney Harbour, New South Wales
, Australia (collectors Thomas Starke-Peterkovic and Les Edwards, December 2001).
It was also cultured by Dr Moore from the stony coral Leptastrea purpurea (Faviidae
) of One Tree Island
Great Barrier Reef
, Queensland
, Australia
(collectors Karen Miller and Craig Mundy, November 2001).
Through a variety of phylogenetic tests on genes found in similar organisms, researchers were able to relate C. velia to dinoflagellate
s and apicomplexa
ns. Subsequent research studies have also shown that the photosynthetic dinoflagellates, apicomplexans and C. velia share the same lineage, containing a red-algal-derived plastid.
With the use of additional DNA
sequencing, the relationship between C. velia, dinoflagellates and apicoplexans was further confirmed. Genomic DNA of C. velia was extracted for PCR templates and sequences were compared with other species resulting in placement of C. velia on a phylogenetic branch close to the apicomplexans, with the help of biostatistical methods. Although researchers are still uncertain about why apicomplexans would sacrifice their photosynthetic ability and become parasitic, it is suggested that clues might be gathered by studying the evolution of the C. velia plastid relative to dinoflagellates.
are the causative agents of malaria
. Formerly scientists have targeted many drug treatments to the apicoplast in invading malarial cells, showing that the C. velia plastid could serve as a convenient model target for the development of antimalarial drugs. In the laboratory setting working with apicomplexan parasites can be difficult, because they must be plated on live host cells and do not always remain viable for long enough to run the necessary sequence of tests. Chromera velia, is more easily maintained alive, and is related to the parasites, so may potentially provide a laboratory model for work on developing antimalarial treatments. C. velia is able to live independently of its normal animal hosts and can be grown easily and cheaply in a laboratory setting. C. velia is available to purchase from the CCMP culture collection in Maine
USA, and is backed up in other culture collections.
C. velia has helped put the spotlight back on the role of protist research, in various clinical and scientific applications regarding both algae and parasites. Strict separation of botanical protists (algae
) and zoological protists (protozoa
) has been conventional but C. velia may be regarded as a good example of a bridge.
It has typical features of alveolates, being phylogenetically related to apicomplexa
Apicomplexa
The Apicomplexa are a large group of protists, most of which possess a unique organelle called apicoplast and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or...
, and contains a photosynthetic plastid
Plastid
Plastids are major organelles found in the cells of plants and algae. Plastids are the site of manufacture and storage of important chemical compounds used by the cell...
. C. velia uses this organelle as the primary energy source, thus being the closest known autotrophic organism to apicomplexans. It may retain a symbiotic relationship with the coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
around it.
History
Chromera velia was first isolated by Dr Bob Moore (then at Carter Lab, University of SydneyUniversity of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...
) from the stony coral (Scleractinia
Scleractinia
Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian...
, Cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...
) Plesiastrea versipora (Faviidae
Faviidae
Faviidae is a family of Scleractinia. Members of this family are widely sought after for the reef aquarium trade.-Genera:*Astreosmilia Duncan, 1867*Australogyra Veron, 1982*Barabattoai Yabe and Sugiyama, 1941*Bikiniastrea Wells, 1954...
) of Sydney Harbour, New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia (collectors Thomas Starke-Peterkovic and Les Edwards, December 2001).
It was also cultured by Dr Moore from the stony coral Leptastrea purpurea (Faviidae
Faviidae
Faviidae is a family of Scleractinia. Members of this family are widely sought after for the reef aquarium trade.-Genera:*Astreosmilia Duncan, 1867*Australogyra Veron, 1982*Barabattoai Yabe and Sugiyama, 1941*Bikiniastrea Wells, 1954...
) of One Tree Island
One Tree Island (Queensland)
One Tree Island is a small coral cay. It is located near the Tropic of Capricorn in the southern Great Barrier Reef, 96 km due east nor east of Gladstone, Queensland, Australia, and 450 km north of the state capital Brisbane...
Great Barrier Reef
Great Barrier Reef
The Great Barrier Reef is the world'slargest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres over an area of approximately...
, Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
(collectors Karen Miller and Craig Mundy, November 2001).
Special features of C. velia plastid
The plastid of Chromera velia has 4 membranes and contains chlorophyll a, while chlorophyll c is missing. Unlike other eukaryotic algae which use UGG as codons for encoding tryptophan, the plastid of C. velia uses codon UGA to encode tryptophan at seven conserved position in the psbA gene. The UGA-Trp codon is characteristic of apicoplast plastids, and the mitochondria of various organisms, and until the discovery of C. velia, was unprecedented in any photosynthetic plastid. Discovery of this organism has provided a model to study the evolution of Apicomplexa.Evolution
The discovery of Chromera velia and its unique plastid which is similar in origin to the apicoplasts, provides an important link in the evolutionary history of the apicomplexans. It is hypothesized that apicomplexans, with their unique relic chloroplast, the apicoplast, were once able to synthesize energy via photosynthesis by the apicoplast. However, this autotrophic mechanism was lost and apicomplexans have slowly evolved to become a parasitic species dependent on hosts for survival.Through a variety of phylogenetic tests on genes found in similar organisms, researchers were able to relate C. velia to dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
s and apicomplexa
Apicomplexa
The Apicomplexa are a large group of protists, most of which possess a unique organelle called apicoplast and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or...
ns. Subsequent research studies have also shown that the photosynthetic dinoflagellates, apicomplexans and C. velia share the same lineage, containing a red-algal-derived plastid.
With the use of additional DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
sequencing, the relationship between C. velia, dinoflagellates and apicoplexans was further confirmed. Genomic DNA of C. velia was extracted for PCR templates and sequences were compared with other species resulting in placement of C. velia on a phylogenetic branch close to the apicomplexans, with the help of biostatistical methods. Although researchers are still uncertain about why apicomplexans would sacrifice their photosynthetic ability and become parasitic, it is suggested that clues might be gathered by studying the evolution of the C. velia plastid relative to dinoflagellates.
Importance
One potentially important contribution that C. velia has to offer the community besides its role as a missing link between parasitic and algal species, is its use in studies aimed at finding a malaria vaccine. Parasites in the apicomplexan genus PlasmodiumPlasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
are the causative agents of malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
. Formerly scientists have targeted many drug treatments to the apicoplast in invading malarial cells, showing that the C. velia plastid could serve as a convenient model target for the development of antimalarial drugs. In the laboratory setting working with apicomplexan parasites can be difficult, because they must be plated on live host cells and do not always remain viable for long enough to run the necessary sequence of tests. Chromera velia, is more easily maintained alive, and is related to the parasites, so may potentially provide a laboratory model for work on developing antimalarial treatments. C. velia is able to live independently of its normal animal hosts and can be grown easily and cheaply in a laboratory setting. C. velia is available to purchase from the CCMP culture collection in Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
USA, and is backed up in other culture collections.
C. velia has helped put the spotlight back on the role of protist research, in various clinical and scientific applications regarding both algae and parasites. Strict separation of botanical protists (algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
) and zoological protists (protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
) has been conventional but C. velia may be regarded as a good example of a bridge.