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Name derivation:
Gracilaria= L. gracilis: thin, slender, or graceful G. tikvahiae = Named for Tikvah Edelstein, a Canadian phycologist from Israel, who conducted extensive floristic and taxonomic studies of seaweeds in the Canadian Maritime Provinces G. vermiculophylla= L. vermicular: worm-like or shaped like a worm+ Gr. phyla: leaf
Classification:
Gracilaria Greville 1830; 172 of 322 species descriptions are currently accepted taxonomically (Guiry and Guiry 2014). Order Gracilariales; family Gracilariaceae
Morphology:
Gracilaria: = Multiaxial, parenchymatous and lacking central filamentous hyphae Gracilaria tikvahiae. algae are erect, to 40 cm tall, solitarily or clustered, green to deep red, and initially attached by discoid holdfasts. Axes highly polymorphic, delicate to coarse, terete at bases, compressed to markedly flat . Drift algae are often terete to slightly compressed at forks and often dominated by tetrasporophytes. Branches are spreading, irregular, and with 2-many per forking. Gracilaria vermiculophylla. An introduced Asiatic alga. Thallus 20-100 cm long, with fleshy, cylindrical “worm-like” axes, black to purple-brown in color, 2-3 (-5) mm in diam., and initially attached by a discoid base. Axes alternately to irregularly branched for 2-5 orders and branches are tapered to the tips while bases may be slightly constricted.
Similar genera:
Cystoclonium purpureum, but it has filamentous medullary filaments versus anatomical features of Gracilaria noted above.
Habitat:
In the Northwest Atlantic Gracilaria tikvahiae is often abundant in scattered estuarine sites, particularly north of Cape Cod. It extends to the Canadian Maritime Provinces. Gracilaria vermiculophylla has spread rapidly in the NWA, being initially recorded in Virginia in 1998; now occurs northwards to New Hampshire. Both species may occur abundantly as detached drift populations, particularly in more northern environments.
Cultivation:
Large-scale production of more than 30 species of cultivated Gracilaria has increased more than 11,500 fold in China from 2001 - 2015. A major contribution of the production is amelioration of pollution from animal mariculture that has increased 16 fold since 1980 to annual production of 1.6 megatons in 2014 (Yang et al. 2015). The authors document the high yield and fast growth rate of G. lemaneiformis, its ease of harvest from horizontal lines, and its highly efficient uptake of NH4-N and PO4-P within 23 days. Nutrient removal along with growth inhibition of toxic phytoplankton (85 – 100% depending on species) makes cultivation of G. lemaneiformis the preferred biological strategy for reducing the harmful phytoplankton.
Use in foods:
Gracilaria spp. are among the most preferred ‘sea vegetable’ foods in Asia. Hydrogels (agars) from Gracilaria spp. are an important product that provide various textures to food (Sousa and Goncalves 2015). Phycoerithrin, a water soluble red pigment, is extracted from Gracilaria and used commercially to modify food color (Sudhakar et al. 2014), and along with allophycocyanin is used in fluorescence energy transfer analysis in flow cytometry (Batard et al. 2002).
Use in pharmacy:
Prostoglandins are paracrines (locally acting hormones) in most human body tissues and physiological systems. They can be synthesized chemically at relatively high cost, while biological production appear to be more efficient. The COX gene produces the enzymes cyclooxygenase and peroxygenase, is expressed in Gracilaria vermiculophylla, that catalyze the reduction of arachidonic acid (AA, a precursor) to prostaglandin H2 (PGH2). The gene has been cloned into E. coli to successfully produce PGH2 more efficiently than other genetic sources to date, although an exogenous source of AA must be added (Kanamoto et al. 2011). The gene has also been cloned into a liverwort, Marchantia polymorpha that produces AA making the production less expensive (Takemura et al. 2012). In both cases the cost of prostaglandin production has been significantly reduced.
Use in mariculture:
Aqueous (1%) and methanolic (0.1%) extracts of Gracilaria edulis significantly reduced loss of the shrimp Macrobrachium rosenbergii to ‘white spot syndrome virus’ by enhancing the shrimp immune response (Arizo, M.A.M. and M.B.B. Maningas 2014).
References:
Arizo, M.A.M. and M.B.B. Maningas 2014. International Workshop on Resource Enhancement and Sustainable Aquaculture Practices in Southeast Asia. 5-7 March, Punta Villa Resort, Iloilo City, Philippines. Poster 17. Batard, P., J. Szollosi, I. Luescher, J-C Cerottini, R. MacDonald and P. Romero 2002. Use of phycoerythrin and allophycocyanin for fluorescence resonance energy transfer analyzed by flow cytometry: Advantages and limitations. Cytometry 48:97-105. Bellorin, A.M., M. C. Oliveira, and E. C. Oliveira. Gracilaria vermiculophylla: a western Pacific species of Gracilariaceae (Rhodophyta) first recorded from the eastern Pacific. Phycol Res 52: 69-79. Freshwater, D.W., F. Montgomery , J. K. Greene, R. M. Hamner, M. Williams, and P. E. Whitfield. 2006. Distribution and identification of an invasive Gracilaria species that is hampering commercial fishing operations in southeastern North Carolina,USA. Biol Invas 8:631-637. Guiry, M.D. and G.M. Guiry 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 30 May 2014. Gurgel, C.F.D., S. Fredericq, and J. M. Norris. 2004. Phylogeography of Gracilaria tikvahiae (Gracilariaceae, Rhodophyta): a study of genetic discontinuity in a continuously distributed species based on molecular evidence. J Phycol 40: 748-758. Kanamoto, H., M. Takemura and K. Ohyama 2011. Identification of a cyclooxygenase gene from the red alga Gracilaria vermiculophylla and bioconversion of arachidonic acid to PGF2a in engineered Escherichia coli. Applied Microioloical Biotechnology 91:1121-1129. Sousa, A.M.M. and M.P. Goncalves 2015. The influence of locust bean gum on native and alkali-modified agar gels. Food Hydrocolloids 44:461-470. Sudhakar, M.P., M. Saraswathi and B.B. Nair 2014. Extraction, purification and application study of R-Phycoerythrin from Gracilaria corticata (J. Agardh) J. Agardh var. corticata. Indian Journal of Natural Products and Resources 5(4):371-374. Takemura, M., H. Kanamoto, S. Nagaya and K. Obyama 2013. Bioproduction of prostaglandins in a ransgenic liverwort, Marchantia polymorpha. Trangenic Research 22:905-911. Taylor, W. R. 1957. Marine Algae of the Northeastern Coast of North America. Revised edition. Univ. Michigan Press., Ann Arbor, ix + 509 pp. Yang, y., z. Chai, Q. Wang, W. Chen, Z. He and S. Jiang 2015. Cultivation of seaweed Gracilaria in Chinese coastal waters and its contribution to environmental improvements. Algal Research 9:236-244.