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Dictyota

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For the genus of silicoflagellates, see Dictyocha.

Dictyota
Dictyota dichotoma at Capo Gallo, Palermo, Sicily
Dictyota dichotoma at Capo Gallo, Palermo, Sicily
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Gyrista
Subphylum: Ochrophytina
Class: Phaeophyceae
Order: Dictyotales
Family: Dictyotaceae
Genus: Dictyota
J.V.Lamouroux, 1809[1]
Type species
Dictyota dichotoma
Species

See text

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 of 2017, some 237 different diterpenes had been identified from across the genus.[2]

Taxonomy and Nomenclature

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The genus Dictyota was first described by Jean Vincent Lamouroux in 1809.[2] 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.[3]

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.[3]  The genera Glossophora, Glossophorella, and Pachdictyon are synonyms of Dictyota as DNA sequencing revealed that they were closely related.[4]

Morphology

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External characteristics

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Dictyota has "flat, ribbon-like axes" which exhibit dichotomous branching that may be either isotomous (equal or symmetrical) or anisotomous (unequal).[3] Isotomous branches may be recurved, while anisotomous branches may become falcate (hooked), or cervicorn, if combined with twisting axes.[3] Apical meristems of Dictyota species have been reported to be either truncate, rounded, or acute.[3] A considerable degree of morphological plasticity has been observed from branching patterns, thus making molecular analyses indispensable when identifying species.[3]

Colors of living thalli range from dark brown to green (as in D. friabilis)[3] or blue (as in D. cyanoloma).[5] 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)[6] while adventitious branches may grow from the central cortical cells.[3] Thalli may also grow hair (20-50 um in diameter).[7] 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).[8]

Thallus of Dictyota dichotoma (Garcia, 1988)

Internal anatomy

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The thalli are parenchymatous 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.).[3]

Distribution

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Dictyota is distributed along tropical to temperate waters with species having generally restricted geographic ranges.[3] It is the most abundant genus of brown algae in the Mediterranean Sea as well as the Atlantic coasts of Europe.[9]

Ecology

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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.[3]

Life History

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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.[10][11]

Dictyota is dioecious and reproduces both sexually and asexually. Release of gametes follows a diurnal and lunar periodicity.[12] Gametes are often released 20–30 minutes after first light,[13] with peaks occurring once or twice a month depending on the species.[14][15] Asexual reproduction may occur via adventitious branching following the loss of the apical meristem.[16]

Chemical Composition

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Dictyota is known to have high levels of fatty acids and lipids which makes the genus ideal for use as feedstock.[17][18] The pigments found in Dictyota are Chlorophyll a, c, fucoxanthin and violaxanthin which are present in a ratio of 13:3:10:1.[19] This ratio may be altered by depth.[20]

Exploitation/Utilization and Management

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The genus is not currently cultivated nor harvested on an industrial scale.[3] It is mainly exploited for its secondary metabolites which are known to have anticoagulant,[21][22] antibacterial,[23] anti-inflammatory[24] 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.[25][26]

Other applications include its use as biofuel - due to the high lipid content of some species[27] - and as supplemental feeds for poultry, cattle, and fish.[3] 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.[28]

Species

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The genus Dictyota contains the following species:[29][30]

References

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  1. ^ Lamouroux, J.V.F. (1809). Exposition des charactères du genre Dictyota, et tableu des espèces qu'il referme. Journal de Botanique (Desvaux) 2: 38-44.
  2. ^ a b Chen, Jiayun; Li, Hong; Zhao, Zishuo; Xia, Xue; Li, Bo; Zhang, Jinrong; Yan, Xiaojun (2018-05-11). "Diterpenes from the Marine Algae of the Genus Dictyota". Marine Drugs. 16 (5): 159. doi:10.3390/md16050159. PMC 5983290. PMID 29751686.
  3. ^ a b c d e f g h i j k l m Bogaert, Kenny A.; Delva, Soria; De Clerck, Olivier (2020-05-12). "Concise review of the genus Dictyota J.V. Lamouroux". Journal of Applied Phycology. 32 (3): 1521–1543. doi:10.1007/s10811-020-02121-4. ISSN 0921-8971. S2CID 218593470.
  4. ^ De Clerck, Olivier; Leliaert, Frederik; Verbruggen, Heroen; Lane, Christopher E.; De Paula, Joel Campos; Payo, Dioli Ann; Coppejans, Eric (2006-11-16). "A REVISED CLASSIFICATION OF THE DICTYOTEAE (DICTYOTALES, PHAEOPHYCEAE) BASED ON rbc L AND 26S RIBOSOMAL DNA SEQUENCE ANALYSES 1". Journal of Phycology. 42 (6): 1271–1288. doi:10.1111/j.1529-8817.2006.00279.x. ISSN 0022-3646. S2CID 84891225.
  5. ^ Steen, Frederique; Aragay, Joana; Zuljevic, Ante; Verbruggen, Heroen; Mancuso, Francesco Paolo; Bunker, Francis; Vitales, Daniel; Gómez Garreta, Amelia; De Clerck, Olivier (2017-01-02). "Tracing the introduction history of the brown seaweed Dictyota cyanoloma (Phaeophyceae, Dictyotales) in Europe". European Journal of Phycology. 52 (1): 31–42. doi:10.1080/09670262.2016.1212998. hdl:10261/170800. ISSN 0967-0262. S2CID 51828243.
  6. ^ Tronholm, Ana; Steen, Frederique; Tyberghein, Lennert; Leliaert, Frederik; Verbruggen, Heroen; Antonia Ribera Siguan, M.; De Clerck, Olivier (2010-11-02). "Species Delimitation, Taxonomy, and Biogeography of Dictyota in Europe (Dictyotales, Phaeophyceae)1". Journal of Phycology. 46 (6): 1301–1321. doi:10.1111/j.1529-8817.2010.00908.x. ISSN 0022-3646. S2CID 85835196.
  7. ^ Müller, S.; Clauss, H. (May 1976). "Aspects of Photomorphogenesis in the Brown Alga Dictyota dichotoma". Zeitschrift für Pflanzenphysiologie. 78 (5): 461–465. doi:10.1016/s0044-328x(76)80095-5. ISSN 0044-328X.
  8. ^ Pedersen, Poul Møller (July 2003). "De Clerck, O.2003. The genus Dictyota (Dictyotales, Phaeophyta) in the Indian Ocean". Nordic Journal of Botany. 23 (3): 344. doi:10.1111/j.1756-1051.2003.tb00403.x. ISSN 0107-055X.
  9. ^ Baweja, P.; Kumar, S.; Sahoo, D.; Levine, I. (2016), "Biology of Seaweeds", Seaweed in Health and Disease Prevention, Elsevier, pp. 41–106, doi:10.1016/b978-0-12-802772-1.00003-8, ISBN 9780128027721, retrieved 2021-12-01
  10. ^ WILLIAMS, J. LLOYD (April 1904). "Studies in the Dictyotaceae". Annals of Botany. os-18 (2): 183–184. doi:10.1093/oxfordjournals.aob.a088957. ISSN 1095-8290.
  11. ^ Hoyt, W. D. (January 1910). "Alternation of Generations and Sexuality in Dictyota dichotoma". Botanical Gazette. 49 (1): 55–57. doi:10.1086/330090. ISSN 0006-8071. S2CID 84023482.
  12. ^ WILLIAMS, J. LLOYD (October 1905). "Studies in the Dictyotaceae". Annals of Botany. os-19 (4): 531–560. doi:10.1093/oxfordjournals.aob.a089027. ISSN 1095-8290.
  13. ^ Phillips, J. A.; Clayton, M. N.; Maier, I.; Boland, W.; Müller, D. G. (September 1990). "Sexual reproduction in Dictyota diemensis (Dictyotales, Phaeophyta)". Phycologia. 29 (3): 367–379. doi:10.2216/i0031-8884-29-3-367.1. ISSN 0031-8884.
  14. ^ MÜLLER, DIETER (1962). "Über jahres- und lunarperiodische Erscheinungen bei einigen Braunalgen". Botanica Marina. 4 (1–2). doi:10.1515/botm.1962.4.1-2.140. ISSN 0006-8055. S2CID 84675238.
  15. ^ Phillips, JA (1992). "Taxonomy and reproduction in Australian species of Diliphus (Dictyotales, Phaeophyta)". Australian Systematic Botany. 5 (6): 657. doi:10.1071/sb9920657. ISSN 1030-1887.
  16. ^ Tanaka, Atsuko; Hoshino, Yoichiro; Nagasato, Chikako; Motomura, Taizo (2016-10-04). "Branch regeneration induced by sever damage in the brown alga Dictyota dichotoma (dictyotales, phaeophyceae)". Protoplasma. 254 (3): 1341–1351. doi:10.1007/s00709-016-1025-4. ISSN 0033-183X. PMID 27704277. S2CID 38764307.
  17. ^ Montgomery, W. Linn; Gerking, Shelby D. (April 1980). "Marine macroalgae as foods for fishes: an evaluation of potential food quality". Environmental Biology of Fishes. 5 (2): 143–153. doi:10.1007/bf02391621. ISSN 0378-1909. S2CID 11118031.
  18. ^ Pillans, R. D.; Franklin, C. E.; Tibbetts, I. R. (February 2004). "Food choice in Siganus fuscescens: influence of macrophyte nutrient content and availability". Journal of Fish Biology. 64 (2): 297–309. doi:10.1111/j.0022-1112.2004.00261.x. ISSN 0022-1112.
  19. ^ Mimuro, Mamoru; Katoh, Tetzuya; Kawai, Hiroshi (February 1990). "Spatial arrangement of pigments and their interaction in the fucoxanthin-chlorophyll ac protein assembly (FCPA) isolated from the brown alga Dictyota dichotoma. Analysis by means of polarized spectroscopy". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1015 (3): 450–456. doi:10.1016/0005-2728(90)90078-i. ISSN 0005-2728.
  20. ^ Perez-Bermudez, P.; Garcia-Carrascosa, M.; Cornejo, M.J.; Segura, J. (January 1981). "Water-depth effects in photosynthetic pigment content of the benthic algae Dictyota dichotoma and Udotea petiolata". Aquatic Botany. 11: 373–377. doi:10.1016/0304-3770(81)90070-x. ISSN 0304-3770.
  21. ^ Costa, L.S.; Fidelis, G.P.; Cordeiro, S.L.; Oliveira, R.M.; Sabry, D.A.; Câmara, R.B.G.; Nobre, L.T.D.B.; Costa, M.S.S.P.; Almeida-Lima, J.; Farias, E.H.C.; Leite, E.L. (January 2010). "Biological activities of sulfated polysaccharides from tropical seaweeds". Biomedicine & Pharmacotherapy. 64 (1): 21–28. doi:10.1016/j.biopha.2009.03.005. ISSN 0753-3322. PMID 19766438.
  22. ^ de Andrade Moura, Laura; Marqui de Almeida, Ana; Domingos, Thaisa; Ortiz-Ramirez, Fredy; Cavalcanti, Diana; Teixeira, Valéria; Fuly, André (2014-04-30). "Antiplatelet and Anticoagulant Effects of Diterpenes Isolated from the Marine Alga, Dictyota menstrualis". Marine Drugs. 12 (5): 2471–2484. doi:10.3390/md12052471. ISSN 1660-3397. PMC 4052301. PMID 24796305.
  23. ^ Chen, Jiayun; Li, Hong; Zhao, Zishuo; Xia, Xue; Li, Bo; Zhang, Jinrong; Yan, Xiaojun (2018-05-11). "Diterpenes from the Marine Algae of the Genus Dictyota". Marine Drugs. 16 (5): 159. doi:10.3390/md16050159. ISSN 1660-3397. PMC 5983290. PMID 29751686.
  24. ^ Zhao, Min; Cheng, Shimiao; Yuan, Weiping; Dong, Jianyong; Huang, Kexin; Sun, Zhongmin; Yan, Pengcheng (2015). "Further New Xenicanes from a Chinese Collection of the Brown Alga Dictyota plectens". Chemical and Pharmaceutical Bulletin. 63 (12): 1081–1086. doi:10.1248/cpb.c15-00556. ISSN 0009-2363. PMID 26377234. S2CID 24649391.
  25. ^ Stirk, Wendy A.; Reinecke, Diana L.; van Staden, Johannes (2007-01-20). "Seasonal variation in antifungal, antibacterial and acetylcholinesterase activity in seven South African seaweeds". Journal of Applied Phycology. 19 (3): 271–276. doi:10.1007/s10811-006-9134-7. ISSN 0921-8971. S2CID 12091706.
  26. ^ Suganthy, N.; Karutha Pandian, S.; Pandima Devi, K. (January 2010). "Neuroprotective effect of seaweeds inhabiting South Indian coastal area (Hare Island, Gulf of Mannar Marine Biosphere Reserve): Cholinesterase inhibitory effect of Hypnea valentiae and Ulva reticulata". Neuroscience Letters. 468 (3): 216–219. doi:10.1016/j.neulet.2009.11.001. ISSN 0304-3940. PMID 19897016. S2CID 3193609.
  27. ^ Gosch, Björn J.; Magnusson, Marie; Paul, Nicholas A.; de Nys, Rocky (2012-05-15). "Total lipid and fatty acid composition of seaweeds for the selection of species for oil-based biofuel and bioproducts". GCB Bioenergy. 4 (6): 919–930. doi:10.1111/j.1757-1707.2012.01175.x. ISSN 1757-1693. S2CID 86480026.
  28. ^ Machado, Lorenna; Magnusson, Marie; Paul, Nicholas A.; de Nys, Rocky; Tomkins, Nigel (2014-01-22). "Effects of Marine and Freshwater Macroalgae on In Vitro Total Gas and Methane Production". PLOS ONE. 9 (1): e85289. Bibcode:2014PLoSO...985289M. doi:10.1371/journal.pone.0085289. ISSN 1932-6203. PMC 3898960. PMID 24465524.
  29. ^ 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 Archived 2018-07-13 at the Wayback Machine on 2018-07-12
  30. ^ a b c M.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.
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