Dictyota Dichotoma Research Articles

Cytotoxic Activities of Green and Brown Seaweeds Collected from Jeju Island against Four Tumor Cell Lines

Methanolic and aqueous extracts from 37 seaweed species (10 green and 27 brown seaweeds) collected from Jeju Island coast were prepared at high (70℃) and room (20℃) temperatures and examined for cytotoxic activity against 4 tumor cell lines: U937 (human monoblastoid leukemia cell line), HL60 (human promyelocytic leukemia cell line), HeLa (woman cervical carcinoma cell line) and CT26 (mouse colon carcinoma line). Both MeOH extracts of Desmarestia tabacoides and Dictyota dichotoma possessed strong cytotoxic activities against all the tumor cell lines tested, but the aqueous extract exhibited no activity. On the other hand Ecklonia cava showed strong cytotoxic activities for the 20℃ aqueous extract against the three tumor cells except HeLa cell. Sagassum coreanum and Sagassum siliquastrum 20℃ aqueous extracts also exhibited strong cytotoxic activities against U937, HL60, HeLa cells. Even though green seaweeds showed less activity than brown seaweeds, 20℃ aqueous extracts of Codium contractum and Codium fragile exhibited strong cytotoxic activities against HL60 or CT26 cells, respectively.

Complete mitochondrial genomes of the three brown algae (Heterokonta: Phaeophyceae) Dictyota dichotoma, Fucus vesiculosus and Desmarestia viridis.

We report the complete mitochondrial sequences of three brown algae (Dictyota dichotoma, Fucus vesiculosus and Desmarestia viridis) belonging to three phaeophycean lineages. They have circular mapping organization and contain almost the same set of mitochondrial genes, despite their size differences (31,617, 36,392 and 39,049 bp, respectively). These include the genes for three rRNAs (23S, 16S and 5S), 25-26 tRNAs, 35 known mitochondrial proteins and 3-4 ORFs. This gene set complements two previously studied brown algal mtDNAs, Pylaiella littoralis and Laminaria digitata. Exceptions to the very similar overall organization include the displacement of orfs, tRNA genes and four protein-coding genes found at different locations in the D. dichotoma mitochondrial genome. We present a phylogenetic analysis based on ten concatenated genes (7,479 nucleotides) and 29 taxa. Stramenopiles were always monophyletic with heterotrophic species at the base. Results support both multiple primary and multiple secondary acquisitions of plastids.

Contribution of exotic species, environmental factors and spatial components to the macrophyte assemblages in a Mediterranean lagoon (Thau lagoon, Southern France)

In the Thau lagoon, located on the French Mediterranean Coast, more than 20% of the macrophyte species are introduced species, likely through shellfish farming. Their impact on local soft substrate macrophyte communities has not yet been evaluated. In this study, we estimate the relationship between introduced species and the assemblage of indigenous macrophytes. Exotic species, environmental factors, and spatial distribution of macrophytes were analyzed with redundancy analysis (RDA) and partial redundancy analysis. We used data from a spatial survey that provided macrophyte densities, environmental characteristics (depth, granulometry, porosity, organic matter, phosphorous and nitrogen concentrations in the sediments), and geographical coordinates of sampling sites. The result of RDA showed that the macrophyte community structure can be explained by pure effects of exotic species (7%), pure effect of environmental factors (18%), pure spatial distribution (11%), and interactions among the above-mentioned variables (20%). Three exotic species ( Dasya sessilis, Chrysymenia wrightii, and Griffithsia corallinoides) were found to have a significant effect on indigenous macrophytes distribution. C. wrightii co-occurring with Cladophora sp. and Radicilingua thysanorhizans, whereas G. corallinoides co-occurring with Cutleria multifida. Depth, porosity, total P and N and the granulometric fraction 0–2 μm were identified as the best environmental predictors. Polysiphonia elongata and Stictyosiphon adriaticus were found in the deepest sites, whereas Nanozostera noltii was correlated with shallow waters. The distribution of Cladosiphon mediterraneus, Gracilaria bursa-pastoris, and Dictyota dichotoma depended on freshwater inputs, whilst Rytiphlaea tinctoria and Halopithys incurva were related with marine water inflows. To further investigate the relationships between species and explanatory variables, logistic regression was used expressing the presence–absence of local species with variables identified during the RDA.

Seasonal stability of sulfuric acid accumulation in the Dictyotales (Phaeophyceae)

SUMMARY Concerning the accumulation of S042- in cells, three types of species are known in the Dictyotales: (i) acidic type (high H2S04 accumulation); (ii) high MgS04 accumulation type; and (iii) nonacidic type (low S042- accumulation). Seasonal changes of intracellular pH and concentrations of inorganic ions were examined in six dictyotalean species. In acidic species (Dictyopteris prolifera (Okamura) Okamura and Spatoglossum eras-sum J. Tanaka), intracellular concentrations of S042- and H+ estimated by pH were high through all seasons. In high MgS04 accumulating species (Dictyotasp. and Padina arborescens Holmes), intracellular concentrations of S042- and Mg2+ were high through all seasons. In nonacidic species (Dictyota dichotoma (Hudson) Lamouroux and Dictyopteris undulata Holmes), intracellular concentration of sulfuric acid ion was low all year round.

Polymorphism in the brown alga Dictyota dichotoma (Dictyotales, Phaeophyceae) from Korea

Two morphotypes of Dictyota dichotoma of uncertain taxonomic status have been identified in Korea. The broad thallus type is common on the south and east coasts of Korea, and is similar to European D. dichotoma in gross morphology. The slender thallus type is only found on the west coast. Morphological differences between the two plant types are evident in their thallus width, their terminal bifurcations, the shapes of apices, and their thallus thickness. The differences in the size and shape of the tetrasporangia and tetraspores are also notable. Plants from the east coast exhibit a dominant asexual annual life-cycle involving sporophytes but not gametophytes, and maintain their population by the production of in-situ germlings. In the slender plants from the west coast, a sexual life-cycle dominates. The rbcL, rbcS, psaA and psbA gene sequence differences between the two morphotypes were congruent with morphological, anatomical and phenological characteristics. In spite of these differences, there is no known inbreeding barrier between these two morphotypes. The Lm/Lc values of the second internodes from two types are also within the range of the species criterion specified by Hornig et al. These results suggest that the two types of D. dichotoma from Korea should be classified as a single species and that they may be in the process of speciation due to geographical isolation (allopatric speciation).

Diterpenes from the Brown Algae Dictyota dichotoma and Dictyota linearis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Dichotenol-A, B and C: the C-16 oxidized seco-dolastanes from the marine brown alga dictyota dichotoma (HUDS.) lamour.

Marine brown alga Dictyota dichotoma (Dictyotaceae) collected from the Karachi coast of the Arabian Sea has yielded three new C-16 oxidized seco-dolastanes (diterpenoids) named dichotenol-A, B and C. Their structures have been characterized with the aid of 2D-NMR spectroscopic techniques.

동해안 울진원전의 온배수 방출이 주변 해조군집에 미치는 영향

In order to clarify the structure and seasonal dynamics of warm tolerant benthic marine algal community in Korea, the species composition and biomass of marine algae at the discharge canal of Uljin nuclear power plant on the East Coast of Korea were investigated seasonally from February 1992 to October 2000. 107 species of marine algae were found at the discharge canal during the past nine years. In general, the number of species observed was abundant in spring or summer and less in autumn or winter. 27 species (4 blue-green, 5 green, 6 brown and 12 red algae) of marine algae occurred more than 1/ 6 frequency and thus can be categorized as warm tolerant species. Among these, one brown (Dictyota dichotoma) and four red algae (Gelidium amansii, Anphiroa ephedraea, Hydrolithon sargassi, Marginisporum crassissimum) are recorded as warm tolerant marine algae for the first time in Korea. Padina arborescens, Anphiroa zonata and Corallina pilulifera were common species found more than 75% frequency. Seasonal fluctuations of mean biomass were 0-1,330 g dry wt m^(-2) and dominant species in biomass were Corallina pilulifera (contribution to a total biomass proportion 34%), Anphiroa zonata (23%), Padina arborescens (18%) and Sargassum micracanthum (11%). The red algae appeared as predominant algal group at the discharge canal of Uljin nuclear power plant in the qualitative and quantitative aspects. The green algae such as Enterornorpha compressa appeared rather frequently at the discharge canal, but the biomass proportion was very low, in contrast to Kori nuclear power plant where there was definite green algal dominance. Differences in algal communities developed at the discharge canals of Uljin and Kori nuclear power plant on the East Coast of Korea, particularly biomass proportions of green algae, can probably be related to local environmental factors such as water velocity through the canal and natural seawater temperatures.

A New Species of Dactylopusioides (Copepoda: Harpacticoida: Thalestridae) Infesting a Brown Alga, Dictyota Dichotoma in Japan

Dactylopusioides fodiens sp. nov. (Copepoda: Harpacticoida: Thalestridae) is described from the west seaboard of Japan on the Sea of Japan. The species infests a brown alga, Dictyota dichotoma. It lives in galleries that it makes by eating the interior of the thallus.

Diterpenes from the brown algae Dictyota dichotoma and Dictyota linearis

Nineteen secondary metabolites of the brown alga Dictyota dichotoma (Huds.) Lam. and fifteen metabolites of the brown alga D. linearis (Ag.) Grev. were isolated and their chemical structures were elucidated on the basis of their NMR and mass spectral data. The diterpenes isopachydictyolal ( 1) from D. dichotoma and 4α-acetyldictyodial ( 2) from D. linearis are new natural products. The antiviral activity of metabolites isolated in adequate amounts was evaluated in laboratory assays against Herpes simplex virus I (HSV I) and Poliomyelitis Virus I, using Vero cells as hosts.

Cyclic AMP levels in several macroalgae and their relation to light quantity and quality

Total cAMP levels were measured in the macroalgae Dictyota dichotoma, Gelidium sesquipedale and Ulva rigida under different light conditions in order to study its regulation either by phytochrome or photosynthesis. Incubation in red or far-red light did not promote a phytochrome-like response; instead, it showed a synergistic effect upon cAMP accumulation. cAMP levels seemed to depend on the amount of energy applied. The correlation between photosynthetic oxygen evolution and cAMP variations at sub-saturating white light irradiance pointed to photosynthetic electron transport as involved in the regulation of cAMP accumulation at least in G. sesquipedale and U. rigida. Inhibitors of thylakoidal and mitochondrial electron transport chains reduced cAMP levels in 70 to 99%. We conclude that cAMP accumulation could be regulated by photosynthetic activity rather than phytochrome in the macroalgae studied.

Dichotenone-A and -B: Two New Enones from the Marine Brown Alga Dictyota Dichotoma (Hudson) Lamour

Marine brown alga Dictyota dichotoma (Dictyotaceae) collected from Karachi coast of Arabian Sea yielded two new (1 and 2) enones (dolastane-diterpenoids) named: dichotenone-A and -B along with an olide (loliolide, 3) as a new source. Their structures have been characterized with the aid of 2D-NMR spectroscopic techniques.

Ring-A Hydroxylated Dolastanes from the Marine Brown Alga Dictyota Dichotoma (HUDS.) Lamour

Marine brown alga Dictyota dichotoma (Dictyotaceae) collected from Karachi coast of Arabian Sea yielded two new dolastane-diterpenoids named: dichototetraol (1) and dichotopentaol (3) along with 2 of the same skeleton as a new source. Their structures have been characterized with the aid of 2D-NMR spectroscopic techniques.

Water-soluble seaweed extracts modulate the respiratory burst activity of turbot phagocytes

In this study, we investigated the effects of water-soluble extracts (WSE) from seaweed species Ulva rigida C. Agardh, Enteromorpha sp., Codium tomentosum (Huds) Stackh., Fucus vesiculosus L., Pelvetia canaliculata (L.) Decne et Thur, Dictyota dichotoma (Huds) Lamour, Chondrus crispus Stackh and Porphyra umbilicalis (L.) J. Agardh, on the respiratory burst of turbot phagocytes, in search of biologically active substances with immunostimulating capacities. The stimulatory capacities of the extracts varied greatly, depending on their origin, the concentrations used and the time of incubation. The best responses were induced by the extracts obtained from U. rigida, Enteromorpha sp. and C. crispus. Pre-incubation of the phagocyte cells with U. rigida and C. crispus extracts and subsequent incubation with phorbol myristate acetate (PMA) showed that these cells responded to further stimulation by this substance and, at some concentrations, they showed higher respiratory burst activity than control cells stimulated by PMA alone, suggesting that the extracts had a priming effect. We also tested the effects of protein-free water-soluble extracts (PF-WSE) and of the polysaccharide fractions (PSF) obtained from the PF-WSE of U. rigida and C. crispus. These extracts induced an increase in the respiratory burst activity of turbot phagocytes, suggesting that most of the stimulatory capacity of the water-soluble extracts was associated with polysaccharides.

86 Chloroplast genome phylogenetics: facts and opinions

Recent progress in sequencing genomes from primary and secondary plastids provided various data including genomic complexities, gene sequences, gene complements, gene cluster organizations and rearrangements as well as secondary gene losses/gene relocations. They are considered to reflect evolutionary traits at different phylogenetic levels. However, current views of the validity of individual data sets are controversial and sometimes appear to reflect opinions rather than facts. Here I will present the plastid genomes of the Xanthophyte Vaucheria bursata and the brown alga Dictyota dichotoma and compare these genomes with those of other algae containing secondary plastids of rhodophytic origin. Gene complement analysis will focus on differential gene losses across evolutionary lineages and gene cluster rearrangements as a consequence of numerous inversions unknown from land plants. It will be discussed whether rearranged gene clusters common to two lineages, to the exclusion of others, may reflect parsimonious events or simply resulted from random independent processes. Although specific characters are encountered among all plastid genomes sequenced to date, the plastid genomes of Vaucheria and Dictyota confirm the presence of a basal set of 46 protein coding genes common to all plastid genomes of algae and metaphytes that have been used to infer a monophyletic origin of primary plastids and their evolutionary offsprings.

148 Life History and Feeding Preferences of Gallery‐Forming Harpacticoids in Dictyotalean Seaweeds

The harpacticoid copepod Dactylopusioides macrolabris has been reported to make galleries beneath the cuticle of cortical cells of Dictyota dichotoma (Dictyotales, Phaeophyceae; Green 1958). Besides this species, we have found several more harpacticoids from Japanese coasts that have similar habits, infesting various dictyotalean species. In laboratory culture experiments growing the harpacticoids for several generations and recording their behaviors by interval video recoding, we have found that these harpacticoids spend most of the lives in the galleries, feeding only on the algal tissues. Different species showed different feeding preferences even among morphologically very close species: one species fed most of the dictyotalean species examined, whereas another species could digest only one species. In order to discuss the evolutionary interactions between the harpacticoids and host seaweeds, comparative molecular phylogenetic analyses of the harpacticoids and host seaweeds were studied using rDNA ITS2 (harpacticoids) and rbcL (Dictyotales) DNA sequences.

Seco-Dolastanes from the Marine Brown Alga Dictyota dichotoma (Huds.) Lamour

Brown alga Dictyota dichotoma (Dictyotaceae) collected from Karachi coast of Arabian Sea yielded two new seco-dolastanes (diterpenoids) named: dichotone and dichotodione along with isolinearol acetate of the same skeleton as a new source. Their structures have been characterized with the aid of 2D-NMR spectroscopic techniques.

Cytotoxic hydroazulene diterpenes from the brown alga Dictyota dichotoma.

Two new hydroazulenoid (prenyl guaiane) diterpenes, dictyone acetate (2) and 3,4-epoxy 13-hydroxy pachydictyol A (4) were isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada, Egypt, together with three known ones, pachydictyol A (1), dictyone (3) and 11-hydroxypachydictyol A (dictyol E) (5). In addition, the steroidal compound, stigmasta-5,(E)-24(28)-dien-3-beta-ol (fucosterol) (6) was also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity.

Role of protective and repair mechanisms in the inhibition of photosynthesis in marine macroalgae.

The mechanism of photoinhibition was investigated in three representative macroalgal species growing on the coast of Patagonia: the chlorophyte Ulva rigida C. Agardh, the rhodophyte Porphyra columbina Montagne and the phaeophyte Dictyota dichotoma (Huds.) Lamour. Dark adapted specimens were exposed to 15 min unfiltered solar radiation to induce photoinhibition, and subsequently the recovery of the photosynthetic quantum yield was followed for up to 6 h. Photoinhibition is believed to be due to the damage and proteolysis of the D1 protein in the reaction center of Photosystem II. During recovery this protein is resynthesized. In order to prove this hypothesis, inhibitors of the chloroplast protein synthesis, streptomycin and chloramphenicol were applied. Both retarded the repair process indicating an inhibition of the D1 protein resynthesis during recovery after the damage they experienced during light exposure. Some algal groups use the xanthophyll cycle to ameliorate the inhibition by excessive light. Dithiothreitol, an inhibitor of violaxanthin de-epoxidase, was administered, to impair the xanthophyll cycle. It strongly affected both photoinhibition and recovery even in the red algal species, which do not have the xanthophyll cycle, indicating that this drug has significant side effects and should be used with caution for the study of the involvement of this protective cycle in algae. Pigmentation was followed in the three species using absorption spectroscopy of thallus extracts at 665 nm during continuous exposure to natural solar radiation or radiation deprived of the UV component during two days. The results indicated a pronounced variation in pigmentation over time due to bleaching and resynthesis. Solar radiation was monitored during the experiments in three channels (UV-B, UV-A and PAR) using an ELDONET instrument on site.

Effect of algal architecture on associated fauna: some evidence from phytal molluscs

In the southern Mediterranean Sea, replicate samples of six common upper-infralittoral algae (Cystoseira barbatula, Cystoseira spinosa, Sargassum vulgare, Halopteris scoparia, Dictyota fasciola, and Dictyota dichotoma) were collected with the major goal of investigating the composition and structure of molluscan assemblages between the algal species. In order to measure the habitat architecture of the six algal species and relate this to the molluscan assemblages, several structural attributes were calculated on each individual plant. There were differences in architectural attributes between the six algal species, with data recorded for S. vulgare and H. scoparia more similar to data for C. barbatula and C. spinosa (which grouped closely), than for the two species belonging to the genus Dictyota, which had a less complex structure. A total of 1,914 specimens and 57 species of molluscs were found on the collected algae. The abundance and diversity of the molluscan assemblages were significantly different between different macroalgae. In general S. vulgare, C. barbatula and C. spinosa supported a higher abundance, greater number of species, Shannon–Wiener diversity, and Margalef's index than the remaining three algal species. Both multivariate analyses (i.e. cluster and multidimensional scaling) and a posteriori tests (Student–Neuman–Keuls' test) demonstrated that samples collected on D. dichotoma were well separated, reflecting the lowest values of abundance and diversity. The molluscan assemblage data were also correlated to the attributes of algal architecture revealing that the combination of degree of branching, algal width and the log of the stem width provides a good explanation for molluscan structure. Differences in the molluscan assemblages of these six common Mediterranean algae can be attributed to different algal architectures, and, consequently, these could be related to the supposed variations in food availability and predation rate.