Ectocarpus Heterocarpus

''Ectocarpus'' is a genus of filamentous brown alga that is 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. The type species for the genus is ''Ectocarpus siliculosus'' ( Dillwyn) Lyngbye. The life history is an isomorphic to slightly kiheteromorphic alternation of generations, but asexual strains also exist.

Taxonomy and Nomenclature

In 1809, Dillwyn described ''Ectocarpus'' as another algae known as ''Conferva siliculosa'' basing from collected specimens 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. These brown algae are known members of heterokonts, which includes diatoms and oomycetes. Ectocarpales is known to be primitive from a phylogenetic standpoint, emerging from a group of brown algae that has recently evolved together with the order Laminariales, a group consisting of kelp species. Phylogenetic analyses are underway to resolve a certain complexity within the genus in order to confirm different species.

Morphology

Studies on morphology have been limited for ''Ectocarpus'' as only two species in the genera (''E. siliculosa'' and ''E. fasciculatus)'' are well-described based on morphology and genetic sequence.

In general, ''Ectocarpus'' is described to be a filamentous algae that can grow up to 30 cm. Cultured specimens in the laboratory tend to be fertile as early as 1–3 cm in length. In unialgal cultures, ''Ectocarpus'' are described to have a branched appearance, in contrast, axenic cultures show ''Ectocarpus'' having a small ball-shaped appearance. ''E. siliculosus'' functions as a model organism in the genus, used as a basis for molecular markers that can aid in understanding genetic polymorphism among species and between life cycles across different locations in the world.

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. While commonly attached to a substrate, thalli of ''Ectocarpus'' may also survive while floating. ''Ectocarpus'' are also commonly found as epiphytes on marine macroflora rather than epilithic, although studies have been limited in evaluating their hosts. On the other hand, ''E. fasciculatus'' is known as an endophyte of Laminaria digitata, but no study has documented how it bypasses the kelp's defense. ''E. crouniorium'' 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, which are either feeding on its thallus or reproductive cells, however, these have not been documented previously. Few have studied the genus' ecology, however, previous studies have shown that temperature affects the life cycle of a few strains which may suggest genetic differences among ''Ectocarpus'' species.

Life History

''Ectocarpus'' has a haplo-diploid life cycle having both sporophyte and gametophyte stages, which 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, which are either male or female wherein their fusion would produce diploid zygotes, restarting the sporophyte stage. Parthenogenesis may also occur when one gamete does not find the opposite, producing a sporophyte.

Cultivation and Exploitation

A protocol has been established in culturing ''Ectocarpus'' in the laboratory using sporophyte filament as a starter, collected and maintained as a strain. ''Ectocarpus'' are able to grow in artificial seawater although a standard medium that can be used is a Provasoli-enriched seawater (PES). Standard laboratory conditions also include 13 degrees Celsius as temperature under 12h light:dark cycle with irradiance at 20 µmol photons m⁻² s⁻¹ using fluorescent lights.

Chemical Composition

Iodide originating from seawater can be accumulated in high concentrations by several brown algae. Among ''Ectocarpus'', enzymes have been identified to be involved iodine emission including some dehalogenases and haloalkane dehalogenases. These enzymes may also aid in defending ''Ectocarpus'' as an epiphyte, against halogenated defenses of its host.

Utilization and Management

''Ectocarpus'' may be vulnerable to an array of pathogens and parasites. In addition, environmental stress caused by temperature, light, and salinity changes. The transcriptome of ''Ectocarpus'' is primarily affected, where gene expression is altered in number despite low to mild stress. Further studies are needed to confirm stress-induced changes in its genes, since there may be other unknown mechanisms it may affect.

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)For information concerning ''Ectocarpus landsburgii'' and link to download of the original description (with image) in Harvey, W.H. (1849)—''Phycologia britannica'' see:
*'' 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

External links

''Ectocarpus'' on algaebase.org

{{Taxonbar, from=Q932568

Ectocarpales
Brown algae genera