''Ectocarpus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of filamentous

brown alga Brown algae (: alga) are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar reg ...

that includes a

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

for the

genomics Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, ...

multicellularity A multicellular organism is an organism that consists of more than one cell, unlike unicellular organisms. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and pa ...

. Among possible model organisms in the brown algae, ''Ectocarpus'' was selected for the relatively small size of its mature thallus and the speed with which it completes its life cycle. Tools available for ''Ectocarpus'' as a model species include a high quality genome sequence and both forward and reverse genetic methodologies, the latter based on CRISPR-Cas9.

Taxonomy and Nomenclature

Brown algae are heterokonts, a group that also includes diatoms and oomycetes. Despite their simple filamentous thalli, the Ectocarpales are part of the crown group of brown algal orders and are a sister group to the order Laminariales (kelps). The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

for the genus is '' Ectocarpus siliculosus'' ( Dillwyn) Lyngbye. In 1809, Dillwyn described ''Ectocarpus'' as ''Conferva siliculosa'' based on specimens collected by W.J. Hooker from Norfolk and East Sussex. In 1819, Lyngbye subsequently described ''Ectocarpus'' using a specimen from Denmark, citing ''C. siliculosa'' Dilwyn as its basionym.

Morphology

Studies on morphology have been limited for ''Ectocarpus'' as only two species in the genera (''E. siliculosus'' and ''E. fasciculatus)'' are well-described based on morphology and genetic sequence. ''Ectocarpus'' is a filamentous alga that can grow up to 30 cm. Cultured specimens in the laboratory tend to be fertile when they are 1–3 cm in length. ''Ectocarpus'' has a normal, branched appearance in unialgal cultures, but in axenic cultures it has a ball-shaped appearance suggesting that bacterial symbionts are required for the alga to attain normal morphology.

Distribution

''Ectocarpus'' can be found across the globe, in temperate shorelines growing as epiphytes on other flora (e.g. seagrass, other alga) or on rocky substrates (epilithic). While commonly attached to a substrate, thalli of ''Ectocarpus'' may also survive while floating. ''Ectocarpus'' are more commonly found as epiphytes on marine macroflora rather than epilithic. ''E. fasciculatus'' is known as an endophyte of ''Laminaria digitata'', but no study has documented how it bypasses the kelp's defense. ''E. crouaniorum'' are found in the intertidal zone while ''E. siliculosus and E. fasciculatus'' can be found in mid-intertidal and subtidal zones, respectively.

Ecology

''Ectocarpus'' thalli tend to shelter several marine invertebrates (e.g. crustaceans and nematodes) and some protists. Temperature affects the life cycle of some strains. A study of the life cycles of natural populations in NW France and SW Italy found marked isomorphy between generations in some populations and evidence of populations with modified, asexual life cycles.

Life History

In the laboratory, the life history is an isomorphic to slightly heteromorphic alternation of generations, but asexual strains also exist. ''Ectocarpus'' has a haploid-diploid life cycle with both sporophyte and gametophyte generations. It can complete its whole life cycle within 3 months in the laboratory. Diploid sporophytes give rise to haploid meiospores which will then produce a haploid gametophyte generation. These gametophytes are dioecious, producing either male or female gametes, which fuse to produce diploid zygotes, restarting the sporophyte stage. Parthenogenesis may also occur when a gamete does not find a gamete of the opposite sex, producing a parthenosporophyte. Deployment of the sporophyte developmental program requires two TALE homeodomain transcription factors, OUROBOROS and SAMSARA. If either of the genes encoding these two proteins is dysfunctional, the alga develops as a gametophyte.

Cultivation and Exploitation

A protocol has been established to culture ''Ectocarpus'' in the laboratory. ''Ectocarpus'' is able to grow in artificial seawater although the standard medium is Provasoli-enriched seawater (PES). Standard laboratory conditions are growth at 13 degrees Celsius under a 12h:12h light:dark cycle with irradiance at 20 μmol photons m⁻² s⁻¹.

Chemical Composition

Iodide originating from seawater can accumulate to high concentrations in several brown algae but high levels are not observed in ''Ectocarpus''. Genes predicted to encode enzymes involved in iodine metabolism have been identified in ''Ectocarpus'', including haloperoxidases, dehalogenases and haloalkane dehalogenases. These enzymes may be part of the defence mechanism of ''Ectocarpus'' against halogenated defenses of brown algal hosts when growing as an epiphyte.

Utilization and Management

''Ectocarpus'' is vulnerable to an array of pathogens and parasites and is also sensitive to abiotic stresses such as shifts in temperature, light and salinity. Major modifications to the ''Ectocarpus'' transcriptome have been observed following stress treatments.

List of species

Some currently accepted species of ''Ectocarpus'' include: *'' Ectocarpus acanthophorus'' Kützing *'' Ectocarpus acutoramulis'' Noda *'' Ectocarpus acutus'' Setchell & N.L.Gardner *'' Ectocarpus adriaticus'' Ercegovic *'' Ectocarpus affinis'' Setchell & N.L.Gardner *'' Ectocarpus aleuticus'' Kützing *'' Ectocarpus auratus''

Bory de Saint-Vincent Jean-Baptiste Geneviève Marcellin Bory de Saint-Vincent was a French naturalist, officer and politician. He was born on 6 July 1778 in Agen (Lot-et-Garonne) and died on 22 December 1846 in Paris. Biologist and geographer, he was particularly int ...

ex Kützing *'' Ectocarpus balakrishnanii'' V.Krishnamurthy *'' Ectocarpus barbadensis''

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*'' Ectocarpus berteroanus'' Montagne *'' Ectocarpus bombycinus'' Kützing *'' Ectocarpus borealis'' ( Kjellman) Kjellman *'' Ectocarpus bracchiolus'' Lindauer *'' Ectocarpus brachiatus'' ( Smith) S.F.Gray *'' Ectocarpus brevicellularis'' Noda *'' Ectocarpus caliacrae'' Celan *'' Ectocarpus capensis'' Kützing *'' Ectocarpus caspicus'' Henckel *'' Ectocarpus chantransioides'' Setchell & N.L.Gardner *'' Ectocarpus chapmanii'' Lindauer *'' Ectocarpus chnoosporae'' Børgesen *'' Ectocarpus cladosiphonae'' Noda *'' Ectocarpus clavifer'' J.Agardh *'' Ectocarpus commensalis'' Setchell & N.L.Gardner *'' Ectocarpus commixtus'' Noda *'' Ectocarpus confusiphyllus'' Noda *'' Ectocarpus congregatus''

Zanardini Giovanni Antonio Maria Zanardini (12 June 1804, Venice – 24 April 1878) was an Italian physician and botanist who specialized in the field of phycology. In 1831 he obtained his medical doctorate from the University of Padua, followed by a degree ...

Vickers Vickers was a British engineering company that existed from 1828 until 1999. It was formed in Sheffield as a steel foundry by Edward Vickers and his father-in-law, and soon became famous for casting church bells. The company went public in 18 ...

*'' Ectocarpus ramentaceus'' Zanardini *'' Ectocarpus rotundatoapicalis'' Noda &

Honda commonly known as just Honda, is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate automotive manufacturer headquartered in Minato, Tokyo, Japan. Founded in October 1946 by Soichiro Honda, Honda has bee ...

*'' Ectocarpus rudis'' Zanardini *'' Ectocarpus rufulus'' Kützing *'' Ectocarpus rufus'' ( Roth) C. Agardh *'' Ectocarpus sadoensis'' Noda *'' Ectocarpus sargassicaulinus'' Noda *'' Ectocarpus sargassiphyllus'' Noda *'' Ectocarpus saxatilis'' Zanardini *'' Ectocarpus scytosiphonae'' Noda *'' Ectocarpus shiiyaensis'' Noda *'' Ectocarpus shimokitaensis'' Ohta *'' Ectocarpus siliculosus'' (Dillwyn) Lyngbye *'' Ectocarpus simpliciusculus'' C. Agardh *'' Ectocarpus simulans'' Setchell & N. L. Gardner *'' Ectocarpus sonorensis'' E. Y. Dawson *'' Ectocarpus sphaericus'' Ohta *'' Ectocarpus strigosus'' Zanardini *'' Ectocarpus tamarinii'' Børgesen *'' Ectocarpus taoniae'' Setchell & N. L. Gardner *'' Ectocarpus tappiensis'' Ohta *'' Ectocarpus tasshaensis'' Noda *'' Ectocarpus trichophorus'' H. Gran *'' Ectocarpus tsugaruensis'' Ohta *'' Ectocarpus variabilis'' Vickers *'' Ectocarpus venetus'' Kützing *'' Ectocarpus vungtauensis'' P. H. Hô *'' Ectocarpus yezoensis'' Yamada & Tanaka *'' Ectocarpus zonariae'' W. R. Taylor *'' Ectocarpus zosterae'' Noda & Ohta

References

External links

''Ectocarpus'' on algaebase.org
{{Taxonbar, from=Q932568 Ectocarpales Brown algae genera