Genus Gracilaria Research Articles

Differentiation of Male Gametes in Gracilaria verrucosa (Rhodophyta, Gracilariales)

The development of male gametes (spermacia) in the red alga Gracilaria verrucosa has been studied using methods of transmission electron microscopy. Early spermatangia located along the wall of the conceptacle show an elongated shape in the thin sections. In the central part of the electron-dense cytoplasm of these cells there is a nucleus; numerous fibrous vesicles are arranged in the periphery. During the process of differentiation, the spermatangia become more rounded in shape and a large spermatangial vesicle is developed. The subsequent development of spermatium is accompanied by polarization of the spermatangium and the subsequent excretion of the spermatangial vesicle. The spermatia are oval cells containing a nucleus and fibrous vesicles. The process of differentiation of male gametes in G. verrucosa does not differ from that in five species of the genus Gracilaria, where it has already been studied. However, any conclusions about the degree of similarity between the spermatia in all the studied species can be made only after a detailed comparative analysis of the ultrastructural characteristics of these gametes.

Red Algae of the Genus Gracilaria in the South of the Russian Far East

Proceeding from our original data and the information available in the literature, we described the biology, ecology, and physiology of the species of the genus Gracilaria inhabiting the south of the Far East. A conclusion is reached about the prospects of commercial cultivation of Gracilaria in Primorye. Recommendations are provided for the cultivation of this species.

PHYLOGENETIC SELECTION OF A RESOURCE: A NEW USE FOR CLADISTICS

A phylogenetic model for the selection of commercial resources using the cladistic method is proposed. The group selected as an example was the marine agarophyte red algal genus Gracilaria Greville. We suggest the use of the cladistic principle of evolutionary transformational series in order to test the quality of agars instead of the assay‐herror traditional method that consumes time and budget. If we asume that the “good quality of agar” in extant taxa is a sinapomorphic character (but not a reliable taxonomic one), then taxa included in the same monophiletic clade in which the species with “good quality of agar” are, has a high evolutionary posibility to share that character. In order to do this we have to incorporate to the set of available specific characters, those of the taxa actually used as a agar source but not present in the area under scope. A complete set of the basic cladistic data required for run the most popular program currently in use (PAUP) are provided. We applied the model to the Mexican Atlantic species and found that, using Gracilaria chilensis and G. cornea as “indicator taxa,” and found Mexican populations of G. crassissima, G. caudata, G. cervicornis and Gracilariopsis lemaneiformis are candidates for a study of yield and agar properties.

ADVANCES IN A MONOGRAPH OF THE GENUS GRACILARIA (RHODOPHYTA) IN THE MEXICAN ATLANTIC

Some species of the genus Gracilaria Greville (Gracilariales, Rhodophyta) are the main source of agar. For that reason, the taxonomic study of the taxon has become relevant for many scholars. In order to bring the Mexican floristics knowledge of the genus into the state‐of‐the‐art about it, we have initiated the needed monography. The character definition has proved to be the most important task. We have found that the most reliable characters for the species delimitation are: general form of the thallus, length and width; form of the axes, length and width; branching pattern; number of axes from the holdfast; form of the holdfast; presence of constrictions at the base of the branches or not; color; length of the segments; consistency; form of the apices; length and thickness of the stipes; surface texture of the branches, smooth, crispidous, etc; adherency to herbarium paper; cellular forms of the transition from cortex to medulla, size and thickness of celular walls of the cells involved; number of celular layers of the cortex, subcortex (if present) and medulla; form, number and distribution of the spermatangial conceptacles; form and size of the cystocarps, if constricted at the base or sessile; diameter of the ostiole and if it is apiculated or not; disposition of the carposporangial chains; form of the gonimoblastic cells, and form and number of tetrasporangia. A diagramatic description for each is provided.

Chemical structure and quality of agars from Gracilaria

Agar polymers synthesized by species of the genus Gracilaria constitute a complex mixture of molecules, containing several extremes in structure. Sulphate hemi-esters, methyl ethers and pyruvic ketals can alter in a number of ways the structural regularity of agar based on strictly 3-O-linked β-l-galactopyranose and 4-O-linked α-l-galactopyranose residues. In comparison with agars from Gelidium and Pterocladia, agars from Gracilaria can have higher degrees of sulphation, methoxylation and pyruvylation. The gelling ability of agars from most of Gracilaria species is considerably improved by adopting, before extraction, an alkali pretreatment which converts α-l-galactose 6 sulphate into 3,6-anhydro-α-l-galactose. Native agars obtained from Gracilaria cannot be classified, with few exceptions, as bacteriological grade agar as they have a high content of methoxyls and consequently high gelling temperatures. On the contrary, the genus Gracilaria is considered the most important source of food and sugar-reactive grade agars. Among techniques which can be used to study algal polysaccharides, combined 1H and 13C nuclear magnetic resonance spectroscopy represent the most effective and powerful method for the investigation of the chemical structure of agarocolloids.

Two terete species of Gracilaria and Gracilariopsis (Gracilariales, Rhodophyta) in Britain

Abstract Two terete species of gracilarioid algae are described for the British Isles. Gracilaria gracilis comb. nov. and Gracilariopsis longissima comb. nov. (Gracilariopsis verrucosa nom. rej. prop.) are superficially similar species long confused under the name Gracilaria verrucosa (Hudson) Papenfuss (= G. confervoides (Stackhouse) Greville), until recently regarded as the type species of the genus Gracilaria Greville. They occur regularly on southern British coasts, often in the same locality, both inter- and subtidally. Gracilariopsis longissima is also recorded for the first time from France and Spain. A lectotype is selected for Gracilaria gracilis, Gracilariopsis longissima is neotypified, and new descriptions are given, including field characters and new details of vegetative and cystocarp structure obtained by sectioning in standard planes, using metachromatic dyes. The British record for Gracilariopsis lemaneiformis (Bory) Dawson, Acleto et Foldvik is not confirmed. Revision of those definition...

Taxonomic studies of the genus Gracilaria (Gracilariales, Rhodophyta) from Australia

The taxonomic history of the genus Gracilaria in Australia is reviewed, and nine species are described and illustrated in detail. Two (G. comosa and G. stipitata) are newly described, and the new name G. cliftonii is proposed for the species previously known as G. furcellata Harvey [non G. furcellata (Montagne) Zanardini = Sarconema filiforme (Sonder) Kylin]. New records and observations are given for four species [G. harveyana J.Agardh, G. preissiana (Sonder) Womersley, G. salicornia (C.Agardh) Dawson, and G. urvillei (Montagne) Abbott in Abbott, Zhang & Xia], and two species [G. blodgettii Harvey and G. cf. vieillardii Silva in Silva, Menez & Moe] are added to the Australian flora. An additional seven or eight species that are incompletely known also occur on the continent and are briefly discussed but not illustrated. For nomenclatural and anatomical reasons we propose that G. spinulosa (Okamura) Chang & Xia forma srilankia Chang & Xia, based on G. purpurascens Harvey ex J. Agardh [non G. purpurascens (Hudson) Greville = Cystoclonium purpurascens (Hudson) Kutzing] and not yet recorded from Australia, be elevated to species status as G. srilankia (Chang & Xia) comb. nov. We propose that Gracilaria harveyana J. Agardh 1885 be conserved against Polyides flagelliformis Sonder 1845, which Professor H.B.S. Womersley has determined is an obscure but earlier name for this well-known Western Australian species.

Suspended farming of Gracilaria chilensis (Rhodophyta, Gigartinales) at Cariquilda River, Maullín, Chile

The algal genus Gracilaria has become the major source of commercial agar extraction in Chile. Recently G. chilensis Bird, McLachlan and Oliveira has been extensively cultivated in Southern Chile in response to wild crop deterioration. This paper evaluates the performance of this species under suspended cultivation, using ropes at two different depths. Treatments including different algal inoculum and harvesting methods were evaluated. Moreover, monthly thallus losses and epiphyte abundance were quantified. The highest biomass production was found in treatments placed at 0.5 m from the bottom. Factors such as light and water movement seem to regulate temporal patterns of biomass variation. Epiphytes exhibited a more marked incidence in the warmer months and were seen to be abundant in stands with a small algal inoculum. Finally, estimated yields of Gracilaria reach values close to 100 t·ha −1·yr −1 fresh weight. These data, together with small losses of algal thalli, suggest good economic opportunities for this suspension culture system.

FATTY ACID DISTRIBUTION AMONG SOME RED ALGAL MACROPHYTES1

ABSTRACTMacrophytic members of the Rhodophyta, which were grown under controlled conditions, were analyzed for their fatty acid distribution. Significant differences were found between some species of the Gelidiales and Gracilariales. Two dominant polyunsaturated fatty acids of the 20 carbon chain group, 20:4ω6 and 20:5ω3, were found in all the Gelidiales species, whereas only 20:4ω6 was found in the Gracilariales species. An inverse relationship between the content of these two polyunsaturated fatty acids in Gelidiales species and among the two groups of species are reported and discussed. All other fatty acid characteristics were more or less similar in these two orders. We cannot draw any solid conclusion about the relationship between Gracilariopsis cf. lemaneiformis (formerly Gracilaria lemaneiformis) and the genus Gracilaria, since our results (the existence of 20:4ω6 and 20:5ω3 in Gracilariopsis) contradict results found by other researchers. The diverse growth conditions of photon flux density and temperature caused some differences in the distribution of the fatty acids in each species. These differences could not explain the different results in similar species reported in the literature.

Morphology, reproduction and taxonomy of the Mediterranean species of Gracilaria (Gracilariales, Rhodophyta)

Abstract Species of the marine algal genus Gracilaria (Gracilariaceae, Rhodophyta) reported from the Mediterranean are critically reassessed. Nine species are recognized: Gracilaria armata (C. Agardh) J. Agardh, G. bursapastoris (S.G. Gmelin) Silva, G. conferta (Schousboe ex Montagne) J. Feldmann et G. Feldmann, G. corallicola Zanardini, G. dendroides Gargiulo, De Masi et Tripodi, G. dura (C. Agardh) J. Agardh, G. heteroclada (Montagne) J. Feldmann et G. Feldmann, G. longa Gargiulo, De Masi et Tripodi, and G. verrucosa (Hudson) Papenfuss. Descriptions and distributional data are provided for these species, and a synoptic key to their features is presented. An examination of the reproductive morphology of these species suggests that the currently accepted criteria for distinguishing between the genera Gracilaria, Hydropuntia (Polycavernosa) and Gracilariopsis are not sustainable, particularly with regard to the development and nutrition of the developing carposporophyte and the formation of sperrnatangia.

Distribution of eicosapentaenoic and arachidonic acids in different species of Gracilaria

The fatty acid compositions of Gracilaria verrucosa, G. bursa-pastoris, G. debilis and Gracilaria sp. were determined. Arachidonic and eicosapentaenoic acids predominated among the fatty acids. The arachidonic: eicosapentaenoic acid ratio in algae of the genus Gracilaria fell into three categories. The fatty acid content in G. verrucosa was not influenced significantly by environmental factors. An error in the identification of several morphologically similar Gracilaria species as G. verrucosa may be responsible for the discrepancy in the literature data about the arachidonic and eicosapentaenoic acid contents in this species. Possible pathways of eicosapentaenoic acid biosynthesis from arachidonic or from α-linolenic acids in red algae are discussed.

Circular plasmid DNAs from the red alga Gracilaria chilensis

Total cellular DNA extracted from eight red algal species (from the genera Gracilaria, Gracilariopsis, Porphyra and Gymnogongrus) was centrifuged on Hoechst dye/CsCl gradients. In five species, plasmid-like DNAs banded with the A+T rich organellar DNAs in the CsCl gradients. Based on their electrophoretic migration in different agarose gels, the plasmid-like DNAs are circular. This is the first report of putative plasmid DNAs in the red algae outside the genus Gracilaria. Two similar Gracilaria chilensis plasmid-like DNAs of 3.8 and 3.4 kb (GC2 and GC3) were cloned in pUC19. The cloned GC2 DNA did not hybridize to either the organellar or nuclear genomes of G. chilensis, suggesting that GC2 is a true plasmid. GC2 did hybridize to the plasmid of one other red algal species, Gracilaria sordida.

Marine red algae of the Coffs Harbour region, northern New South Wales

The marine benthic red algae of the Coffs Harbour region are described and illustrated in detail. The survey constitutes the first ever detailed descriptive and illustrative mainland regional monograph of any area along the entire eastern Australian seaboard. Collections made intertidally and to depths of 20 m have included 119 species in 74 genera, 26 families, and 8 orders of Rhodophyta, of which 54 (45%) were previously unrecorded from eastern Australia, 22 (18%) are new records for the whole of Australia (16 being new Southern Hemisphere records), 1 (Dictyothumnion) constitutes a new genus, and 16 (13%) are new species in the genera Gracilaria, Curdiea, Botryocladia, Dictyothamnion, Antithamnion, Ceramium, Callithumnion, Anotrichium, Nitophyllum, Phycodrys, Apoglossum, Dasya, Fernandosiphonia, and Herposiphonia. Also included are major Australian revisions of the genera Martensia and Nitophyllum, and six new combinations are proposed (Chondria infestans, Curdiea angustata, Dasya pilosa, Haraldiophyllum sinuosum, Myriogramme pulchellum, and Stenograrnme phyllophoroides). The Coffs Harbour flora, although related to the north-eastern and, to a lesser degree, southern Australian floras, has a number of species previously known only from much more remote localities, such as Japan (6 species), California (4 species), New Zealand (3 species), India (2 species), South America (2 species), the Galapagos Islands (1 species), China (1 species), South Africa (1 species), and the Mediterranean (1 species). Twelve of the 22 species newly recorded for Australia show a definite western Pacific distribution, a region with which the overall Coffs Harbour flora has strong affinities.

The New Zealand species ofGracilariaGreville (Rhodophyta, Gigartinales)

Abstract In a taxonomic revision of the New Zealand species of the genus Gracilaria (Rhodophyta, Gigartinales) three species are recognised:-G. secundata Harvey, G. sordida sp. nov., and G. truncata Kraft. A further species, at present of uncertain position, is discussed, and excluded names and records are listed. G. secundata, originally described from New South Wales, Australia, occurs in the southern North Island, South, Stewart, Chatham, and Auckland Islands; G. sordida sp. nov. and G. truncata appear to be endemic to New Zealand and occur throughout the North, South and Stewart Islands, with G. sordida sp. nov. also recorded from the Chatham Islands.

Prostaglandin E2: A candidate for causative agent of "ogonori" poisoning.

Two cases of human intoxication resulting from consumption of red marine algae Gracilaria verrucosa (Japanes name, ogonori) and G. chorda (tsurushiramo) have recently occurred in Japan. Large amounts of inorganic salts present in these seaweeds has been suggested to be responsible for the poisoning. We however found that the extracts prepared from these algae which had been steeped in freshwater evoked severe diarrhea in mice; the main symptom of human victims. Two active principles have been isolated pure from G. verrucosa that was soaked in distilled water for20h. The principal compound was identified to be prostaglandin E2 by spectral data, chemical transformation and direct comparison with authentic specimens, while the less active substance to be prostaglandin A2. Responsibility of the prostaglandins, particularly PGE2, for the “ ogonori ” poisoning has been suggested. It was also proposed that an inhibitor of prostaglandin synthesis is present in the algae of the genus Gracilaria.

Transfer of the New Zealand red algaTylotus proliferus(Gracilariaceae, Gigartinales) to the genusGracilaria

Abstract Reproductive material of Tylotus proliferus (Harvey) Kylin from the North Island of New Zealand has been examined and found to conform to the genus Gracilaria. Because the name Gracilaria prolifera Reinsch is in current use for an alga from South Georgia in the subantarctic, the new name G. truncata is proposed, based on a prominent branch feature of the New Zealand species. Details of habit, vegetative morphology, and carposporophyte development of G. truncata are presented. The so-called “nutritive filaments” which characterise this and many other species of Gracilaria arc discussed, and substitution of the term “traversing filaments” is suggested to avoid implying an unverified nourishment function of these structures. Some speculations on the possible relatives of G. truncata are made.

The Algal Genus Gracilaria in Australia.Valerie May

Previous articleNext article No AccessNew Biological BooksThe Algal Genus Gracilaria in Australia. Valerie May PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 25, Number 2Jun., 1950 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/397591 PDF download Crossref reports no articles citing this article.

On the Origin of the Cystocarp in the Genus Gracilaria

On the Origin of the Cystocarp in the Genus Gracilaria