• Source: Ectocarpus

Ectocarpus is a genus of filamentous brown alga that includes a model organism for the genomics of multicellularity. 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 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-Vincentex Kützing
Ectocarpus balakrishnanii V.Krishnamurthy
Ectocarpus barbadensis Kuckuck
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
Ectocarpus constanciae Hariot
Ectocarpus corticulatus De A.Saunders
Ectocarpus crouanii Thuret
Ectocarpus crouaniorum Thuret
Ectocarpus cryptophilus Børgesen
Ectocarpus cymosus Zanardini
Ectocarpus cystophylloides Noda
Ectocarpus dellowianus Lindauer
Ectocarpus denudatus P.L.Crouan & H.M.Crouan
Ectocarpus dictyoptericola Noda
Ectocarpus distortus Carmichael
Ectocarpus divergens Kornmann
Ectocarpus ensenadanus N.L.Gardner
Ectocarpus erectus Kützing
Ectocarpus exiguus Skottsberg
Ectocarpus exilis Zanardini
Ectocarpus falklandicus Skottsberg
Ectocarpus fasciculatus Harvey (syn: Ectocarpus Landsburgii Harvey; named after the rev. David Landsborough)
Ectocarpus fenestroides P. L. Crouan & H. M. Crouan
Ectocarpus flagelliferus Setchell & N. L. Gardner
Ectocarpus flagelliformis Kützing
Ectocarpus fructuosus Setchell & N. L. Gardner
Ectocarpus fulvescens Schousboe ex Thuret
Ectocarpus fungiformis Oltmanns
Ectocarpus fusiformis Nagai
Ectocarpus giraudiae J. Agardh ex William M. Wilson
Ectocarpus glaziovii Zeller
Ectocarpus gonodioides Setchell & N. L. Gardner
Ectocarpus hamulosus Harvey & J. W. Bailey
Ectocarpus hancockii E. Y. Dawson
Ectocarpus heterocarpus P. L. Crouan & H. M. Crouan
Ectocarpus hornericola Noda
Ectocarpus humilis Kützing
Ectocarpus intermedius Kützing
Ectocarpus isopodicola E. Y. Dawson
Ectocarpus kellneri Meneghini
Ectocarpus kjellmanioides Noda
Ectocarpus laminariae Noda
Ectocarpus laurenciae Yamada
Ectocarpus lepasicola Noda
Ectocarpus macrocarpus Harvey
Ectocarpus macrocarpus P. L. Crouan & H. M. Crouan
Ectocarpus minor Noda
Ectocarpus minutissimus Skottsberg & Levring
Ectocarpus minutulus Montagne
Ectocarpus mitchellioides Noda
Ectocarpus monzensis Noda & Konno
Ectocarpus multifurcus Zanardini
Ectocarpus myurus Zanardini
Ectocarpus natans Zanardini
Ectocarpus niigatensis Noda
Ectocarpus nitens De Notaris
Ectocarpus oblongatus Noda
Ectocarpus obovatus Foslie
Ectocarpus obtusocarpus P. L. Crouan & H. M. Crouan
Ectocarpus obtusus Noda
Ectocarpus parvulus Kützing
Ectocarpus pectenis Ercegović
Ectocarpus penicillatus (C. Agardh) Kjellman
Ectocarpus plasticola Noda
Ectocarpus plumosus Noda
Ectocarpus polysiphoniae Noda
Ectocarpus pumilus Zanardini
Ectocarpus radicans Zanardini
Ectocarpus rallsiae Vickers
Ectocarpus ramentaceus Zanardini
Ectocarpus rotundatoapicalis Noda & Honda
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






Further reading


Bourdareau, Simon; Tirichine, Leila; Lombard, Bérangère; Loew, Damarys; Scornet, Delphine; Wu, Yue; Coelho, Susana M.; Cock, J. Mark (2021). "Histone modifications during the life cycle of the brown alga Ectocarpus". Genome Biology. 22 (1). Springer Science and Business Media LLC. doi:10.1186/s13059-020-02216-8. ISSN 1474-760X.
Ahmed, Sophia; Cock, J. Mark; Pessia, Eugenie (2014). "A Haploid System of Sex Determination in the Brown Alga Ectocarpus sp". Current Biology. 24 (17): 1945–1957. doi:10.1016/j.cub.2014.07.042. PMID 25176635.
Tarver, James E.; Cormier, Alexandre; Pinzón, Natalia; Taylor, Richard S.; Carré, Wilfrid; Strittmatter, Martina; Seitz, Hervé; Coelho, Susana M.; Cock, J. Mark (2015). "microRNAs and the evolution of complex multicellularity: identification of a large, diverse complement of microRNAs in the brown algaEctocarpus". Nucleic Acids Research. 43 (13). Oxford University Press (OUP): 6384–6398. doi:10.1093/nar/gkv578. ISSN 0305-1048.
Prigent, Sylvian (2014). "The genome-scale metabolic network of Ectocarpus siliculosus (EctoGEM): a resource to study brown algal physiology and beyond". Plant Journal. 80 (2): 367–381. doi:10.1111/tpj.12627. PMID 25065645.




External links


Ectocarpus on algaebase.org

Kata Kunci Pencarian:

• Postelsia
• Ectocarpus
• Ectocarpus siliculosus
• Brown algae
• Long Island Sound
• Extracellular matrix
• Brine
• Ectocarpene
• Ectocarpaceae
• Maullinia
• Phaeovirus