''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (

diterpene Diterpenes are a class of terpenes composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primary ...

s) which have potential medicinal value. As at the end of 2017, some 237 different diterpenes had been identified from across the genus.

Taxonomy and Nomenclature

The genus ''Dictyota'' was first described by Jean Vincent Lamouroux in 1809. The name ''Dictyota'' is derived from the Greek word “Διχτυον” meaning “net” or “network”, referring to the inner cellular structure of specimens when viewed under a microscope, which features netted cortical and medullary cells. ''Dictyota'' belongs to the order Dictyotales and the SSDO-clade, which also includes the orders Sphacelariales, Syringodermatales, and Onslowiales. The family Dictyotaceae is divided into two tribes: Dictyoteae and Zonarieae. The former have a single lens-shaped apical cell from which the thallus grows, while the latter are characterized by a row or cluster of apical cells. The genera ''Glossophora'', ''Glossophorella'', and ''Pachdictyon'' are synonyms of ''Dictyota'' as DNA sequencing revealed that they were closely related.

Morphology

External characteristics

''Dictyota'' has "flat, ribbon-like axes" which exhibit dichotomous branching that may be either isotomous (equal or symmetrical) or anisotomous (unequal). Isotomous branches may be recurved, while anisotomous branches may become falcate (hooked), or cervicorn, if combined with twisting axes. Apical meristems of ''Dictyota'' species have been reported to be either truncate, rounded, or acute. A considerable degree of morphological plasticity has been observed from branching patterns, thus making molecular analyses indispensable when identifying species. Colors of living thalli range from dark brown to green (as in ''D. friabilis'') or blue (as in ''D. cyanoloma''). The thalli grow from apical cells which differentiate into an outer cortical and an inner medullary cell layer. Cortical cells on the margins of the thalli may grow into leaf-like projections or teeth (as in ''D. ciliolata'' and ''D. cyanoloma'') while adventitious branches may grow from the central cortical cells. Thalli may also grow hair (20-50 um in diameter). Thalli attach to the substrate via rhizoids which are multicellular, uniseriate, branching, and hyaline (glassy or transparent). Different species may have one or several attachment points which can lead to a wide range of growth forms (i.e. creeping thalli or fully erect). Dictyota-dichotoma-19880601-a

Internal anatomy

The thalli are

parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

tous and are characterized by one or more apical cells that divide into an outer cortical and an inner medullary cell layer which can have several different configurations (e.g. uni-layered cortex with unilayered medulla, uni-layered cortex with multi-layered medulla, etc.).

Distribution

''Dictyota'' is distributed along tropical to temperate waters with species having generally restricted geographic ranges. It is the most abundant genus of brown algae in the Mediterranean Sea as well as the Atlantic coasts of Europe.

Ecology

Species of the genus are commonly found in subtidal to intertidal rocky pools. Seasonality in species' abundances as well as fertility are driven mainly by temperature, photoperiod, and solar radiation. For instance, populations of ''D. dichotoma'' in the southern hemisphere are highly abundant for a majority of the year but are largely absent in the warmer months, which is when its northern counterparts are most abundant and fertile.

Life History

''Dictyota'' exhibits an isomorphic life cycle wherein the alternating gametophyte and sporophyte phases appear morphologically similar. This alternation co-occurs with a change in ploidy. The gametophytes produce gametes which undergo fertilization to produce the diploid sporophyte, which then produces sporangia which will release 4 haploid spores through meiosis. Half of the haploid spores will develop into the female gametophytes while the other half will develop into male gametophytes, starting the process over again. ''Dictyota'' is

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

and reproduces both sexually and asexually. Release of gametes follows a diurnal and lunar periodicity. Gametes are often released 20–30 minutes after first light, with peaks occurring once or twice a month depending on the species. Asexual reproduction may occur via adventitious branching following the loss of the apical meristem.

Chemical Composition

''Dictyota'' is known to have high levels of fatty acids and lipids which makes the genus ideal for use as feedstock. The pigments found in ''Dictyota'' are Chlorophyll ''a'', ''c,'' fucoxanthin and violaxanthin which are present in a ratio of 13:3:10:1. This ratio may be altered by depth.

Exploitation/Utilization and Management

The genus is not currently cultivated nor harvested on an industrial scale. It is mainly exploited for its secondary metabolites which are known to have anticoagulant, antibacterial, anti-inflammatory properties, among others, making them useful for a wide range of pharmaceutical applications. For instance, there is evidence that methanolic extracts of ''Dictyota'' inhibits the butyrylcholinesterase (BuChE) enzyme in humans, which could potentially treat Alzheimer's disease. Other applications include its use as biofuel - due to the high lipid content of some species - and as supplemental feeds for poultry, cattle, and fish. A study in 2014 found that feeds with ''D. bartayresiana'' supplements could potentially reduce in vitro methane production of ruminants by 92.2%, which may have implications for reducing emissions from the agricultural sector.

Species

The genus ''Dictyota'' contains the following species:Guiry, M.D. & Guiry, G.M. (2018). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway (taxonomic information republished from AlgaeBase with permission of M.D. Guiry). Dictyota J.V.Lamouroux, 1809. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=144086 on 2018-07-12M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org/search/genus/detail/?genus_id=oe101e7b01e405395 ; searched on 12 July 2018. *''

Dictyota acutiloba ''Dictyota acutiloba,'' the twisted dictyota, is a species of brown seaweed in the family Dictyotaceae. The species has been found in the Mediterranean Sea, and it has been thought that it got there via the Suez Canal The Suez Canal (; , ') i ...

'' J.Agardh, 1848 *'' Dictyota adhaerens'' Noda, 1965 *'' Dictyota adnata''

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 ...

, 1878 **'' Dictyota adnata f. nana'' Post *''

Dictyota aegerrima ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end ...

'' ( Allender & Kraft) De Clerck, 2006 *''

Dictyota alternifida ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals ( diterpenes) which have potential medicinal value. As at the en ...

'' J.Agardh, 1894 *''

Dictyota anastomosans ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals ( diterpenes) which have potential medicinal value. As at the en ...

'' Steen et al. *'' Dictyota apiculata var. Agardh'' Weber-van Bosse *'' Dictyota asiatica'' I.K.Hwang *'' Dictyota attenuata'' P.Crouan & H.Crouan, 1842 *'' Dictyota bartayresiana'' J.V.Lamouroux, 1809 **'' Dictyota bartayresiana var. divaricata'' Kützing *'' Dictyota bifurca'' J.Agardh, 1894 *'' Dictyota binghamiae'' J.Agardh, 1894 *'' Dictyota canaliculata'' O.De Clerck & E.Coppejans, 1997 *'' Dictyota canariensis'' ( Grunow) Tronholm, 2013 *'' Dictyota caribaea'' Hörnig & Schnetter, 1992 **'' Dictyota cervicornis f. pseudodichotoma'' Taylor **'' Dictyota cervicornis f. spiralis'' Taylor **'' Dictyota ceylanica var. anastomosans'' Yamada *'' Dictyota chalchicueyecanensis'' Lozano-Orozco & Sentíes **'' Dictyota ciliata var. humilis'' Grunow *'' Dictyota ciliolata'' Sonder ex Kützing, 1859 *'' Dictyota concrescens'' W.R.Taylor, 1945 *'' Dictyota coriacea'' ( Holmes) I.K.Wang, H.-S.Kim & W.J.Lee, 2004 *'' Dictyota crenulata'' J.Agardh, 1847 *'' Dictyota cribrosa'' Setchell & N.L.Gardner, 1930 *'' Dictyota crinita'' ( J.Agardh) Hörnig, Schnetter & Prud'Homme van Reine, 1992 *''

Dictyota crux ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end o ...

'' **'' Dictyota crux f. parva'' A.Bachmann *'' Dictyota cuneata'' Dickie, 1874 *'' Dictyota cyanoloma'' Tronholm, De Clerck, A.Gómez-Garreta & Rull Lluch, 2010 *'' Dictyota cymatophila'' Tronholm, M.Sanson & Afonso-Carrillo, 2010 *'' Dictyota decumbens'' ( R.W.Ricker) Hörnig, Schnetter & Prud'homme van Reine, 1992 *'' Dictyota detergenda'' Kraft, 2009 *'' Dictyota dhofarensis'' ( Nizamuddin & A.C.Campbell) De Clerck, 2006 *''

Dictyota dichotoma ''Dictyota dichotoma'' is a species of Brown algae found in the temperate western and eastern Atlantic Ocean, the Mediterranean Sea, the Black Sea, the Red Sea and the western Indian Ocean. Description The thallus of ''Dictyota dichotoma'' grows ...

'' ( Hudson) J.V.Lamouroux, 1809 *''

Dictyota harveyana ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end o ...

'' *'' Dictyota hauckiana'' Nizamuddin, 1975 *'' Dictyota humifusa'' Hörnig, Schnetter & Coppejans, 1992 *'' Dictyota implexa'' ( Desfontaines) J.V.Lamouroux, 1809 *'' Dictyota indica'' Anand, 1965 *'' Dictyota inscripta'' J.Agardh, 1893 *'' Dictyota intermedia''

, 1874 *'' Dictyota jamaicensis'' W.R.Taylor, 1960 *'' Dictyota kunthii'' ( C.Agardh) Greville, 1830 *'' Dictyota laciniata'' J.V.Lamouroux, 1809 *'' Dictyota lata'' J.V.Lamouroux, 1809 **'' Dictyota linearis var. campsosticha'' Montagne **'' Dictyota linearis f. intricata'' Kützing **'' Dictyota linearis var. major'' P.Crouan & H.Crouan **'' Dictyota linearis var. minor'' Sonder *'' Dictyota littoralis'' P.Anand, 1965 *'' Dictyota liturata'' J.Agardh, 1848 *'' Dictyota major'' W.R.Taylor, 1945 *'' Dictyota masonii'' Setchell & N.L.Gardner, 1930 *'' Dictyota mayae'' Lozano-Orozco & Sentíes *'' Dictyota mediterranea'' ( Schiffner) G.Furnari, 1997 *'' Dictyota menstrualis'' ( Hoyt) Schnetter, Hörnig & Weber-Peukert, 1987 *'' Dictyota mertensii'' ( C.Martius) Kützing, 1859 *''

Dictyota moniliformis ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals ( diterpenes) which have potential medicinal value. As at the en ...

'' ( J.Agardh) Hörnig, Schnetter & Prud'homme van Reine, 1992 *'' Dictyota multifida'' ( J.E.Smith) Bory, 1838 *'' Dictyota naevosa'' ( Suhr) Montagne, 1840 *'' Dictyota nigrescens''

, 1878 *'' Dictyota nigricans'' J.Agardh, 1882 *'' Dictyota ocellata'' J.Agardh, 1894 *'' Dictyota pachyderma'' Luan Rixiao & Ding Lanping *'' Dictyota paniculata'' J.Agardh, 1841 *'' Dictyota papenfussii'' Lindauer, 1949 **'' Dictyota pavonia var. maxima'' J.V.Lamouroux *'' Dictyota pedrochei'' Lozano-Orozco & Sentíes *'' Dictyota pellucida'' J.Agardh, 1892 *''

Dictyota penicellata ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end ...

'' J.V.Lamouroux *'' Dictyota phlyctaenodes'' Montagne, 1852 *'' Dictyota pinnata'' ( E.Y.Dawson) I.Hörnig, R.Schnetter & Prud'homme van Reine, 1993 *'' Dictyota pinnatifida'' Kützing, 1859 **'' Dictyota pinnatifida var. rigida'' Grunow *'' Dictyota plantaginea'' J.V.Lamouroux ex Frauenfeld, 1855 *'' Dictyota plectens'' ( Allender & Kraft) Kraft, 2009 *'' Dictyota pleiacantha'' Tronholm, 2013 *'' Dictyota polyclada'' Sonder ex Kützing *'' Dictyota pontica'' Sperk, 1869 *'' Dictyota pulchella'' Hörnig & Schnetter, 1988> *'' Dictyota rhizodes'' (

Turner Turner may refer to: People and fictional characters * Turner (surname), a common surname, including a list of people and fictional characters with the name * Turner (given name), a list of people with the given name *One who uses a lathe for tur ...

) J.V.Lamouroux *'' Dictyota rigida'' De Clerck & Coppejans, 1999 *'' Dictyota robusta'' J.Agardh, 1894 *'' Dictyota rotunda'' C.Agardh, 1820 *'' Dictyota sandvicensis'' Sonder, 1859 *'' Dictyota serrulata'' J.V.Lamouroux, 1809 *'' Dictyota spathulata'' Yamada, 1928 *'' Dictyota spinulosa'' J.D.Hooker & Arnott, 1838 *'' Dictyota spiralis'' Montagne, 1846 *'' Dictyota stolonifera'' E.Y.Dawson, 1962 *'' Dictyota suhrii'' ( Kützing) I.Hörnig, R.Schnetter & W.F.Prud'homme van Reine, 1992 *'' Dictyota vieillardii'' Kützing, 1863 **'' Dictyota vieillardii var. filiformis'' Kützing *'' Dictyota virellus'' Noda, 1971 *'' Dictyota vittata'' Kraft, 2009 *'' Dictyota vivesii'' M.A.Howe, 1911

References

{{Authority control Dictyotaceae Brown algae genera Seaweeds