Ectocarpus Fasciculatus Research Articles

Genetic diversity of Ectocarpus (Ectocarpales, Phaeophyceae) in Peru and northern Chile, the area of origin of the genome-sequenced strain.

• The origin of the Ectocarpus strain used for genome sequencing (the 'genome strain') was Peru, where no Ectocarpus had been reported previously. To study the genetic diversity in the region and to increase the number of individuals from this area available for genetic experiments, 119 new Ectocarpus strains were isolated from eight localities along the 3000 km of coastline from central Peru to central Chile. • Internal transcribed spacer 1 (ITS1) genotyping revealed nine different genotypes, five of which were endemic to the area studied and three of which were previously unknown. • Individuals of the same genotype as the genome strain occurred from Peru to northernmost Chile, representing 61% of the samples in this area, from which five more genotypes were isolated. Further south, down to central Chile, most individuals belonged to Ectocarpus siliculosus, Ectocarpus fasciculatus and Ectocarpus crouaniorum. In sexual crosses, the genome strain and the new isolates of the same genotype were fully compatible. • Sequences from four nuclear and cytoplasmic genetic markers (ITS1, ITS2, Rubisco spacer and Cytochrome-c oxidase subunit 3 (cox3)) separated the genome strain from the known species of Ectocarpus. It may in future be recognized as a separate species.

No evidence for the induction of brown algal chemical defense by the phytohormones jasmonic acid and methyl jasmonate.

Induced chemical defense reactions are widespread in marine brown algae. Despite the evidence that the biosynthesis of defense metabolites can be up-regulated upon herbivory, we do not know how this regulation of biosynthetic pathways to secondary metabolites is achieved in brown algae. In higher plants, the phytohormone jasmonic acid (JA) is crucial for the mediation of induced chemical defenses, and several findings of this metabolite from marine sources have been reported. We tested the hypothesis that JA or related metabolites play a role in induced brown algal defense. Quantification of oxylipins with a detection limit around 20 ng g(-1) algal tissue did not reveal the presence of JA in the seven examined brown algal species Dictyota dichotoma, Colpomenia peregrina, Ectocarpus fasciculatus, Fucus vesiculosus, Himanthalia elongata, Saccharina latissima (formerly Laminaria saccharina), and Sargassum muticum. Moreover, treatment with ecologically relevant concentrations of JA and methyl jasmonate did not lead to a significant change in the profile of medium- and non-polar metabolites of the tested algae. Only when high concentrations of > or =500 microg ml(-1) medium of the phytohormones were applied that a metabolic response which could be attributed to unspecific stress was observed. Bioassays with D. dichotoma that focused on medium- and non-polar compounds confirmed the lack of a biological role of JA and methyl jasmonate in the induction of algal induced chemical defenses. The phytohormone-treated samples did not exhibit any increased defense potential towards the amphipod Ampithoe longimana and the isopod Paracerceis caudata. JA and related phytohormones, known to be active in higher plants, thus appear to play no role in brown algae for induction of the defense chemicals studied here.

The marine algal (seaweed) flora of the Azores: additions and amendments

Thirteen species of benthic marine algae are reported new for the isolated mid-Atlantic Azores archipelago and five older records are confirmed. Seven (Bangia atropurpurea, Codium fragile spp. tomentosoides, Ectocarpus fasciculatus, E. siliculosus, Porphyrostromium ciliare, Ulothrix flacca and Ulvaria oxysperma) are widespread amphi-Atlantic species some of which extend in distributional range south to the Canary Islands. Cryptonemia seminervis, Ctenosiphonia hypnoides and Phyllophora sicula are known from the northeastern Atlantic Ocean only and also occur in the Canary Islands. The Azores archipelago is the western limit of distribution of Codium fragile ssp. atlanticum, Bostrychia scorpioides, Bryopsis cupressina, Erythroglossum laciniatum, Haliptilon squamatum and Phyllophora sicula, and the southern limit of C. fragile ssp. atlanticum and E. laciniatum. The tropical species Phyllodictyon anastomosans, Valonia macrophysa and Wurdemannia miniata reach their northern limit of distribution there. Asparagopsis taxiformis is now less common possibly due to competition with the non-native A. armata; subspecies of the non-native C. fragile now occur widely in the Azores. The status of Fucus vesiculosus, Ulva (Enteromorpha) clathrata and Rhizoclonium tortuosum is clarified and other species have been removed from the flora. The continuing addition of new species records for the Azores shows the archipelago to be floristically richer than other Atlantic islands except for the Canary Islands.

Positional distribution of fatty acids on the glycerol backbone during the biosynthesis of glycerolipids in Ectocarpus fasciculatus

The biosynthesis of glycolipids in E. fasciculatus was studied by 14C label and chase. The fatty acids in sulphoquinovosyl diacylglycerol (SQDG) were almost 16-carbon and 18-carbon ones. In addition to the two fatty acids, monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) contained 8.5 mol% and 31.0 mol% of eicosapentaenoic acid (20: 5), respectively, and this fatty acid was usually distributed in the sn-1 position of the glycerol backbone. When plants were incubated with [2−14C] acetate, differences existed in the positional distribution of the labeled fatty acids in sn-1 and sn-2 among the three glycerolipids. In SQDG., 14C-labeled fatty acids were distributed uniformly in the sn-1 and sn-2 positions. In DGDG., 14C-labeled fatty acids were mainly distributed in the sn-2 position. In MGDG., the radioactivity of fatty acids in sn-1 position was far greater than that in sn-2 position after a 30 min pulse label, and the difference in radioactivity between the two positions decreased rapidly. The above results indicated that differences in the positional distribution of 14C-labeled fatty acids between sn-1 and sn-2 positions might be related to 20: 5 and the biosynthesis of DGDG. Our results also suggested that E. fasciculatus had the same DGDG biosynthetic pathway as that in higher plants and galactosyl transferase was selective for MGDG.

Entry of the DNA virus, Ectocarpus fasciculatus virus type 1 (Phycodnaviridae), into host cell cytosol and nucleus

Entry of the DNA virus, Ectocarpus fasciculatus virus type 1 (Phycodnaviridae), into host cell cytosol and nucleus

Entry of the DNA virus, Ectocarpus fasciculatus virus type 1 (Phycodnaviridae), into host cell cytosol and nucleus

SUMMARY The process by which Ectocarpus fasciculatus virus type 1 (EfasV-1) infects zoospores of its brown algal host was studied by electron microscopy. Upon virus attachment to the target cell, the integral membrane component of the viral capsid fuses with the host plasma membrane, and the 140-nm viral DNA-protein core enters the cytosol. Within 5 min after infection, particles resembling viral cores appeared in the nucleus. The entry mechanism of EfasV-1 into the host nucleus remains enigmatic.

Positional distribution of fatty acids on the glycerol backbone during the biosynthesis of glycerolipids in Ectocarpus fas-ciculatus

Positional distribution of fatty acids on the glycerol backbone during the biosynthesis of glycerolipids in Ectocarpus fas-ciculatus

Contribution to the seaweed flora of Namibia: new records of Chlorophyta and Phaeophyceae

Six species of benthic marine Chlorophyta and Phaeophyceae are recorded for the first time from the coast of Namibia: Ectocarpus fasciculatus Harvey, Feldmannia irregularis (Kützing) G. Hamel, Bachelotia antillarum (Grunow) Gerloff, Straguloria clavata (Harvey in Hooker) Hamel, Entocladia leptochaete (Huber) Burrows and Ulvella lens P. Crouan & H. Crouan. Data concerning local and world distribution of these species as well as some taxonomical remarks are provided.

Frequency of viral infection in a field population of Ectocarpus fasciculatus (Ectocarpales, Phaeophyceae)

Filaments of Ectocarpus fasciculatus epiphytic on Laminaria digitata were sampled monthly from the rocky shore at Peveril Point, Swanage, UK, for more than a year and were screened for the presence or absence of overt viral infection. The mean levels of overtly infected filaments recorded per month ranged from 1.1 ± 0.1 % in June 1998 to 4.7 ± 0.2% in February 1999. Significantly higher levels of overt infection occurred during the winter months, and a significant negative correlation existed between this fluctuation and the surface sea temperature. In addition, a highly significant spatial difference was determined in the overt infection incidence on six reef faces.

Phosphatidylglycerol of Ectocarpus fasciculatus (Phaeophyceae). Analysis of molecular species by the use of dinitrobenzoyl diacylglycerol derivatives

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Virus binding to brown algal spores and gametes visualized by DAPI fluorescence microscopy

No abstract available.

PASSAGE OF A MARINE BROWN ALGAL DNA VIRUS FROM ECTOCARPUS FASCICULATUS (ECTOCARPALES, PHAEOPHYCEAE) TO MYRIOTRICHIA CLAVAEFORMIS (DICTYOSIPHONALES, PHAEOPHYCEAE): INFECTION SYMPTOMS AND RECOVERY1

ABSTRACTA dsDNA virus (EfasV‐1) isolated from Ectocarpus fasciculatus Harvey infected Myriotrichia clavaeformis Harvey, a species belonging to a different brown algal order. The virus did not complete its infection cycle in the foreign host but caused infertility due to malformed reproductive structures. After some time in culture, the host's reproductive capacity was sometimes restored with concomitant loss of at least part of the viral genome. This incidence of interordinal virus transfer is discussed in relation to possibilities for virus‐mediated horizontal gene transfer in brown algae.

Lipids of Ectocarpus fasciculatus (Phaeophyceae). Incorporation of [l-14C]Oleate and the Role of TAG and MGDG in Lipid Metabolism

Lipids and fatty acids of Ectocarpus fasciculatus (Ectocarpales, Phaeophyceae) were analyzed. Major polar lipids are monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), diacylglycerylhydroxymethyl-iV.A'j.N-trimethyl/J-alanine (DGTA), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and phosphatidylinositol (PI). Diphosphatidylglycerol (OPG), phosphatidic acid (PA) and phosphatidyl-O-[iV-(2-hydroxyethyl)glycine] (PHEG) were also present in small amounts. Nonpolar lipids mainly consist of triacylglycerol (TAG) and diacylglycerol (DAG). Major fatty acids are 16:0,18:1, al8:3, 18:4, 20:4 and 20:5. The positional distribution of fatty acids showed that molecular species of eukaryotic structure account for 99% in MGDG, 98% in DGDG, 62% in PG and 23% in SQDG. On incubation with [1- 14 C]18:1 for 30 min, 33% of the total label was detected in TAG, 16% in PG, 14% in PE, 10% in PC and 8% in MGDG. During 7 days of chase, the label in TAG, PG, PE and PC decreased and simultaneously increased in MGDG up to 41% of the total. In SQDG, labelled fatty acids were found in prokaryotic as well as in eukaryotic molecular species. During the experiment, the label shifted from 18:1 to 18:2, 18:3,18:4 and, to a minor extent, to 20:4 and 20:5 acids indicating 18:1 to be processed by elongation and/or desaturation. These results suggest TAG to act as a major primary acceptor of exogenous oleate and to be involved in the transfer of fatty acids to MGDG and other polar lipids.

Mendelian genetics in brown algae: inheritance of a lipid defect mutation and sex alleles in Ectocarpus fasciculatus (Ectocarpales, Phaeophyceae)

Thalli of the filamentous brown alga Ectocarpus fasciculatus Harvey contain the betaine lipid diacylglycerylhydroxymethyltrimethyl-β-alanine(DGTA). A sporophyte deficient for DGTA produced DGTA-free gametophytes. We performed a reciprocal bifactorial crossing analysis by mating DGTA-free and wild-type gametes; sex factors served as the second allele pair. The DGTA(+) allele is dominant in both types of hybrid sporophytes. Meiotic segregation of the two allele pairs produced all four possible combinations of sex and DGTA characters, thus showing that these genes are chromosomal and unlinked.

Taxonomic value of a betaine lipid in Ectocarpus (Phaeophyceae) and the first record of a sexual population of E. fasciculatus for the Pacific Ocean

SUMMARYThe betaine lipid DGTA differentiates between two species of Ectocarpus: it is present in E. fasciculatus Harvey, and lacking in E. siliculosus (Dillwyn) Lyngbye, Two ectocarpoid isolates from the coast of Chile, which could not be identified to species level, were found to belong to opposite DGTA types. Culture experiments showed that these plants were sporophytes. Their meiospores produced gametophytes of the species predicted by the lipid analysis. Promoted by this new approach, a sexual population of Ectocarpus fasciculatus has been detected for the first time in the Pacific Ocean.

Filamentous Brown Algae from the Juan Fernandez Archipelago (Chile): Contribution of Laboratory Culture Techniques to a Phytogeographic Survey

The marine benthic floras of many remote localities are poorly studied. Sampling, during a short visit, followed by laboratory culture techniques can be employed to extend the flora lists. Islas Robinson Crusoe and Santa Clara off the coast of central Chile were visited for 10 days in 1991. Small fragments of benthic and sublittoral algae and various substrates were collected and subsequently incubated in the laboratory. The developing ectocarpoid algae were used to establish unialgal cultures. Morphological characters were well expressed, and the following species could be identified and correlated with the taxa reported by Levring in 1941: Ectocarpus fasciculatus, Feldmannia simplex (= Ectocarpus cylindricus Saunders), Hincksia granulosa, H. mitchelliae, H. conifera (= Ectocarpus arabicus Figari et De Notaris) and Kuetzingiella battersii (= Ectocarpus minutissimus Levring)

Distribution and development of some Manx epiphyte populations

The success ofElachista fucicola as an epiphyte ofFucus vesiculosus is partly due to its ability to grow on most parts of the host thallus. Its ability to reach reproductive maturity quickly ensures its fitness, even on temporary structures such as receptacles. Epiphyte distribution may also vary with host morphology.Himanthalia elongata is a basiphyte for several tissue-specific epiphytes:Ectocarpus fasciculatus, Elachista scutulata, Herponema velutinum andMyriactula areschougii are exclusive, or almost so, to receptacles. On growing receptacles their specificity extends to conceptacles, which also provide refuges from grazing. Epiphyte abundance in summer is greatest at the upper and lower limits ofHimanthalia distribution, suggesting that basiphytes living under suboptimal conditions are more prone to infestation by epiphytes. 5–10% ofHimanthalia receptacles are thought to persist over winter and so to facilitate the transmission of epiphytes to the following year's crop of receptacles. The distribution ofEctocarpus fasciculatus onLaminaria digitata differs in pattern from that onHimanthalia. The twoEctocarpus populations also differ morphologically, but both have reproductive and developmental, characteristics that are in accord with the ecological cycles of their basiphytes. This characteristic is likely to be an important factor in determining the success of an epiphyte. Success may also be facilitated by epiphyte variability or by possession of a fixed but well-adapted phenotype. The very high incidence of brown algal epiphytes on growingHimanthalia receptacles does not reflect the composition of the surrounding algal vegetation. The possibility that some host-recognition mechanism operates cannot be discounted.

Viruslike particles in the brown alga Ectocarpus

Mature plants of Ectocarpus fasciculatus were sectioned and the plurilocular sporangia of some plants were found to contain polyhedral viruslike particles. The particles are ca. 170 nm in diameter, possessing both a shell and core, and are confined to the nuclear regions of the developing spores. A possible cylindrical form of this presumed virus is found in some nuclei. The “infection” could be systemic within the plant, and lysis of the zoospores occurs if large numbers of the viruslike particles are present.

Identification of a Cytokinin, 6‐(3 Methyl‐2‐butenylamino) purine, in Sea Water and the Effect of Cytokinins on Brown Algae

AbstractUsing combined gas chromatography and mass spectrometry a growth‐promoting, organic component of sea water has been quantitatively estimated and identified as the cytokinin 6‐(3 methyl‐2‐butenylamino) purine. Additions of this cytokinin, kinetin or sea water from the Fucus‐Ascophyllum zone increased the growth of Ectocarpus confervoides and Pylaiella litoralis in artificial sea water. Additions of kinetin to bacteria‐free cultures of Ectocarpus fasciculatus also initiated the production of upright ectocarpoid filaments.

The occurrence of variant forms in cultures of species ofEctocarpusandGiffordia

Apparent variants, resembling Hecatonema sp., have been isolated from cultures of Ectocarpus fasciculatus Harv., Ectocarpus siliculosus (Dillw.) Lyngb., Giffordia irregularis (Kütz.) Le Jol. and Giffordia mitchellae (Harv.) Hamel. The origin and life history of the hecatonemoid forms is described. Their possible roles are discussed and an argument is presented in support of the hypothesis that they are contaminants.