Immunogold-labeling analysis of alginate distributions in the cell walls of chromophyte algae

The immunogold electron microscopy technique was employed to detect the presence of alginates in the cell walls of selected chromophyte species. Anti-alginate antiserum labeled the cell walls of Sphacelaria and Scytosiphon (Phaeophyceae), Tribonema, Vaucheria, Botrydium, Botrydiopsis (Xanthophyceae) and an‘un-described filamentous species’ (incertae cedis), but it did not label those of Giraudyopsis, Phaeosaccion (Chrysomeridales), Antithamnion (Rhodophyceae) and Bryopsis (Ulvophyceae). This is the first report of the occurrence of alginates in the chromophyte outside Phaeophyceae. The absence of alginates in Chrysomeridales, which has an unclear phylogenetic position, implies a rather distant phylogenetic relationship of the order Chrysomeridales from Phaeophyceae/Xanthophyceae.     

A Comparative Study on Photosynthesis Temperature Relationships and Their Seasonal Changes in Marine Benthic Algae

In each of the species examined — 4 Chlorophyceae, 7 Phaeophyceae and 4 Rhodophyceae — the optimum temperature for photosynthesis was apparently higher in summer material than in winter material. In the brown algae the optimum temperature for the apparent photosynthesis lies between 20°C and 23°C, in the green algae and in most of the red algae between 25° and 30°C. In most of the red algae the activity decreased markedly at 35°GC, while a considerable part of the green algae survived at this temperature. In 50% of the species of brown algae examined the photosynthetic activity decreased at 30°C and was completely lost at 35°C, while in the remaining species a strong resistance to high temperatures was observed.     

A survey of the distribution of UV-absorbing substances in tropical macroalgae

UV-absorbing mycosporine-like amino acid compounds (MAA) were identified and quantified in 13 macroalgal Chlorophyceae, six Phaeophyceae and 28 Rhodophy-ceae collected in the intertidal zone from the tropical island Hainan, People's Republic of China, as well as from tropical mangrove locations in America, Africa, Australia and Japan. All of these habitats receive naturally high solar ultraviolet (UV) irradiances. The study revealed that all Rhodophyceae contained several MAA, which are assumed to function as natural UV sunscreens. Within all species investigated eight distinct compounds were found, seven of which were identified as mycosporine-glycine, shinorine, porphyra-334, pal-ythine, asterina-330, palythinol and palythene. The unknown substance had an absorption spectrum with a maximum at 357 nm. This compound was restricted to two red algal species from Hainan. In contrast, the Chlorophyceae and Phaeophyceae did not contain MAA or exhibited only trace concentrations. Compared with data from the literature, the amount of all MAA in the tropical Rhodophyceae seemed to be higher than in temperate organisms, probably reflecting acclimation to the stronger solar radiation which is typical for lower latitudes. The data suggest that accumulation of MAA may represent a natural defence system against exposure to biologically harmful UV radiation.     

Sterols of some chilean algae

The distribution of sterols in 14 Chilean Rhodophyceae and in Lessonia sp. (Phaeophyceae) has been examined. Cholesterol is present in all the red algae examined. Golidium filicinum contains, in addition desmosterol and 24-methylene-cholesterol. Cholest-7-en-3-β-ol was found in Cryptonemia angustate and Neoagardhiella gaudichaudii. Fucosterol and 24-methylenecholesterol were found in Lessonia sp.     

α-Carotene and its derivatives have a sole chirality in phototrophic organisms?

Carotenoids in eukaryotic phototrophic organisms can be classified into two groups; β-carotene and its derivatives, and α-carotene and its derivatives. We re-examined distribution of α-carotene and its derivatives among various taxa of aquatic algae (17 classes) and land plants. α-carotene and its derivatives were found from Rhodophyceae (macrophytic type), Cryptophyceae, Euglenophyceae, Chlorarachniophyceae, Prasinophyceae, Chlorophyceae, Ulvophyceae, Charophyceae, and land plants, while they could not be detected from Glaucophyceae, Rhodophyceae (unicellular type), Chryosophyceae, Raphidophyceae, Bacillariophyceae, Phaeophyceae, Xanthophyceae, Eustigmatophyceae, Haptophyceae, and Dinophyceae. We also analyzed the chirality of α-carotene and/or its derivatives, such as lutein and siphonaxanthin, and found all of them had only (6'R)-type, not (6'S)-type.     

Action toxique de quatre métaux lourds (cadmium,cuivre, mercure,plomb) sur la croissance d'Asparagopsis armata Harvey (Rhodophycée: Bonnemaisoniale) en culture

The increase in length of Asparagopsis armata Harvey (Rhodophyceae: Bonnemaisoniale) was measured in various concentrations of lead, mercury, cadmium, and copper. Significant reductions of growth rate compared with controls were observed at 3.70 mg · 1^?1 of lead, 0.31 mg · 1^?1 of cadmium, and 0.092 mg · 1^?1 of copper. The minimal lethal concentration is 0.0296 mg · 1^?1 for mercury, 18.3 mg · 1^?1 for cadmium, and 1.85 mg · 1^?1 of copper.     

Quantification of Selected Endogenous Hydroxy-oxylipins from Tropical Marine Macroalgae

The present study investigated the contents of hydroxy-oxylipins hydroxyoctadecadienoic acids (HODEs), hydroxyoctadecatrienoic acids (HOTrEs), and hydroxyeicosatetraenoic acids (HETEs) in 40 macroalgae belonging to the Chlorophyceae, Rhodophyceae and, Phaeophyceae. The hydroxy-oxylipin content was low and ranged from 0.14?±?0.012 ng/g (Codium dwarkense) to 8,161.9?±?253 ng/g (Chaetomorpha linum) among the Chlorophyceae, 345.4?±?56.8 ng/g (Scytosiphon lomentaria) to 2,574.5?±?155.5 ng/g (Stoechospermum marginatum) among the Phaeophyceae, and 19.4?±?2.2 ng/g (Laurencia cruciata) to 1,753.1?±?268.2 ng/g in Gracilaria corticata v. folifera) among the Rhodophyceae on fresh weight basis (p?≤?0.01). The concentrations of C18-oxylipins were greater than C20-oxylipins in all the investigated macroalgae, except forUlva linza, Codium sursum, Dictyopteris deliculata, S. marginatum, Sargassum tenerrimum, Gracilaria spp. (except G. textorii), Rhodymenia sonderi, and Odonthalia veravalensis.The macroalgal species rich in HODEs, HOTrEs, and HETEs were segregated using principal component analysis. The red macroalgae showed the highest contents of HETEs, followed by brown and green macroalgae in consistent with their PUFA profiles. The relative contents of isomeric forms of oxylipins displayed the species-specific positional selectivity of lipoxygenase (LOX) enzyme in macroalgae. All the species exhibited 13-LOX specificity for linoleic acid analogous of higher plants, while 21 out of 40 species showed 9-LOX selectivity for the oxygenation of α-linolenic acid. No trend was observed for the oxygenation of arachidonic acid in macroalgae, except for in the Halymeniales, Ceramiales (except L. cruciata), and Corallinales. This study infers that LOX products, octadecanoids and eicosanoids, described in macroalgal taxa were similar to those of higher plants and mammals, respectively, and thus can be utilized as an alternative source of chemically synthesized oxylipin analogues in therapeutics, cosmetics, and nutritional oil supplements.     

REVIEWS

American Botany , 1873–1892. Decades of Transition. By A ndrew D enny R odgers III.
Flora of Illinois. By G eorge N eville J ones .
Fragmenta Papuana. [ Observations of a Naturalist in Netherlands New Guinea. ] By H. J. L am .
Root Disease Fungi . By S. D. G arrett .
Structure and Reproduction of the Algae. Vol. 11. Phaeophyceae, Rhodophyceae, Myxophyceae. By F elix E. F ritsch     

Antibakterielle Inhaltsstoffe in Algen

Zusammenfassung 1. Die Aufarbeitungsmethoden zur Gewinnung antibakterieller Extrakte aus Meeresalgen werden im Hinblick auf Haltbarkeit und Trocknung des Materials untersucht.2. Die antibakteriellen Eigenschaften der Präparate aus 9 Chlorophyceen, 16 Rhodophyceen und 16 Phaeophyceen gegen 4 gram-positive und 2 gram-negative Bakterienstämme werden bestimmt.3. Die stärksten antibakteriellen Eigenschaften finden sich bei den Chlorophyceen. Von den Rhodophyceen haben nurChondrus crispus, Laurencia pinnatifida, Delesseria sanguinea und zum Teil auchRhodomela confervoides, von den PhaeophyceenHalidrys siliquosa, Fucus, Laminaria digitata undDesmarestia viridis eine deutliche Hemmwirkung.4. Bei den Rhodophyceen und Chlorophyceen kommen überwiegend nur hydrophile, bei den Phaeophyceen auch mit lipophilen Lösungsmitteln extrahierbare Hemmstoffe vor.5. BeiDumontia incrassata liegen leicht flüchtige, schwach wirksame Hemmstoffe vor; beiDesmarestia viridis geht die Antibiose auf eine Verschiebung des pH-Wertes des Kulturmediums durch die aus den Thalli hinausdiffundierende Schwefelsäure zurück.

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Antibacterial components in algae1. Contribution

Antibiotic components and intensity activities have been determined in several seaweed species. In order to obtain suitable preparations revealing antibacterial activities, several methods have been tested with respect to stability and desiccating the material. Antibiotic properties have been determined in preparations of 9 Chlorophyceae, 16 Rhodophyceae, and 16 Phaeophyceae using as criterion populations growth of 4 gram-positive and 2 gram-negative bacteria strains. The most potent antibiotic properties occur in Chlorophyceae. Among the Rhodophyceae tested, onlyChondrus crispus, Laurencia pinnatifida, Delesseria sanguinea, and — to a lesser degree —Rhodomela confervoides show considerable antibiotic activities. Among the Phaeophyceae, antibacterial potentials occur inHalidrys siliquosa, Fucus, Laminaria digitata, andDesmarestia viridis. The antibiotic compounds of Rhodophyceae and Chlorophyceae are mainly hydrophilic, whereas those of Phaeophyceae are in part extractible with hydrophobic solvents.Dumontia incrassata contains volatile compounds with a low antibiotic activity. The antibacterial properties ofDumontia incrassata are due to acidification of the culture medium by sulfuric acid, diffusing from the thalli into the agar.

     

LIGHT INDEPENDENT CARBON FIXATION BY MARINE MACROALGAE1

Several marine macroalgae representative of the Chlorophyceae, Rhodophyceae and Phaeophyceae were investigated for their potentials of photosynthesis and light independent (dark) carbon fixation. In addition, the activities of ribulose-1,5-bisphosphate carboxylase (RubP-C; EC 4.1.1.39) and of phosphoenolpyruvate carboxykinase (PEP-CK; EC 4.1.1.32) were studied. In contrast to the green and red algae investigated, all brown algae exhibited comparably high rates of dark fixation accounting for up to 20% of photosynthetic carbon uptake. These observations are confirmed by the activities of RubP-C and PEP-CK measured after extraction from different species and thallus regions. Dark fixed ¹⁴C was mainly recovered from aspartate, citrate, malate, glutamate, and alanine. Appreciable amounts of ¹⁴C were incorporated into insoluble (polymeric) constituents even after relatively short periods of dark fixation.     

Further connections between the benthic marine algal floras of the northern Arabian Sea and Japan

Identifications made on some recent collections of benthic marine algae from the Sultanate of Oman, northern Arabian Sea, have revealed several new records for this region. A total of eight species, representing five species of Rhodophyceae, two species of Phaeophyceae, and a single species each of Chlorophyceae, are newly reported for Oman. Of particular interest is the fact that these species represent new records for the Indian Ocean, some of which had previously been known from Japan and environs.     

Whole community estimates of macroalgal pigment concentration within two southern New Zealand kelp forests1

Light availability is a fundamental factor that controls the productivity and distribution of macroalgae and is highly variable, both spatially and temporally, in subtidal coastal systems. Our comprehension of how macroalgae respond to such variability is a significant knowledge gap that limits our understanding of how light influences the structure and productivity of these environments. Here, we examined the pigment characteristics of individual species, and for the first time the whole community, within one low‐light, and one high‐light kelp‐forest system in southern New Zealand. The aim was to quantify the range of pigmentation seen within the two kelp‐forests which differed in irradiance regime. Light availability was 33% and 64% greater at the high‐light compared to the low‐light site at 2 and 10 m depth, respectively. Results suggested Phaeophyceae species at deeper depths in the low‐light site may be living at the edge of their photosynthetic ability and pigment synthesis appeared significantly restricted. Even with greater investment in the pigment fucoxanthin, biomass of Phaeophyceae species was significantly lower in the low‐light site. Highly pigmented Rhodophyceae species made a greater proportional contribution to community biomass within the low‐light site where they likely possessed a photosynthetic advantage. This work helps explain discrepancies in community structure between the two study sites and explores the complex relationship between irradiance and photoacclimation. The comparison of community pigment concentration holds potential as a tool for assessing the relative degree of photoacclimation occurring between sites and provides a proxy of photosynthetic cost under a specific light regime.     

Carboxylating enzymes and pathway of photosynthetic carbon assmilation in different marine algae—Evidence for the C4-pathway?

Experiments on short-term photosynthesis in H¹⁴CO₃ ^- (2–5 s) using various species of different algal classes resulted in predominant ¹⁴C-labelling (>90% of total ¹⁴C-incorporation) of phosphorylated compounds. The percentage of malate and aspartate usually accounts for distinctly less than 10% of the total ¹⁴C-labelling. These findings are consistent with data from enzymatic analyses, since 97–100% of the carboxylation capacity is due to ribulose-1.5-biphosphate carboxylase (EC 4.1.1.39) in Rhodophyceae and Chlorophyceae. Phaeophyceae are generally characterized by considerable activity of phosphoenolpyruvate carboxykinase (EC 4.1.1.32): at least 10% of carboxylation is confined to this enzyme. Similar ratios are obtained when rates of photosynthesis and of light-independent CO₂-fixation are compared. Activity of phosphoenolpyruvate carboxylase (EC 4.1.1.31) could not be detected in the species investigated. The results are discussed with emphasis on the pathway of photosynthetic carbon assimilation in marine algae.Abbreviations PEP-CK phosphoenolpyruvate carboxykinase (EC 4.1.1.32) - PEP-C phosphoenolpyruvate carboxylase (EC 4.1.1.31) - RubP-C ribulose-1.5-biphosphate carboxylase (EC 4.1.1.39) Dedicated to Professor H. Fischer, Bonn, on his 65th birthday     

Arctic marine phytobenthos of northern Baffin Island

Global climate change is expected to alter the polar bioregions faster than any other marine environment. This study assesses the biodiversity of seaweeds and associated eukaryotic pathogens of an established study site in northern Baffin Island (72° N), providing a baseline inventory for future work assessing impacts of the currently ongoing changes in the Arctic marine environment. A total of 33 Phaeophyceae, 24 Rhodophyceae, 2 Chlorophyceae, 12 Ulvophyceae, 1 Trebouxiophyceae, and 1 Dinophyceae are reported, based on collections of an expedition to the area in 2009, complemented by unpublished records of Robert T. Wilce and the first‐ever photographic documentation of the phytobenthos of the American Arctic. Molecular barcoding of isolates raised from incubated substratum samples revealed the presence of 20 species of brown seaweeds, including gametophytes of kelp and of a previously unsequenced Desmarestia closely related to D. viridis, two species of Pylaiella, the kelp endophyte Laminariocolax aecidioides and 11 previously unsequenced species of the Ectocarpales, highlighting the necessity to include molecular techniques for fully unraveling cryptic algal diversity. This study also includes the first records of Eurychasma dicksonii, a eukaryotic pathogen affecting seaweeds, from the American Arctic. Overall, this study provides both the most accurate inventory of seaweed diversity of the northern Baffin Island region to date and can be used as an important basis to understand diversity changes with climate change.     

PRIMARY PRODUCTION,CALCIFICATION, AND AIR-SEA CO2 FLUXES OF A MACROALGAL-DOMINATED CORAL REEF COMMUNITY (MOOREA,FRENCH POLYNESIA)1

Community metabolism and air-sea carbon dioxide (CO₂) fluxes were investigated in July 1992 on a fringing reef at Moorea (French Polynesia). The benthic community was dominated by macroalgae (85% substratum cover) and comprised of Phaeophyceae Padina tenuis (Bory), Turbinaria ornata (Turner) J. Agardh, and Hydroclathrus clathratus Bory (Howe); Chlorophyta Halimeda incrassata f. ovata J. Agardh (Howe); and Ventricaria ventricosa J. Agardh (Olsen et West), as well as several Rhodophyta (Actinotrichia fragilis Forskál (Børgesen) and several species of encrusting coralline algae). Algal biomass was 171 g dry weight· m^?2. Community gross production (P_g), respiration (R), and net calcification (G) were measured in an open-top enclosure. P_g and R were respectively 248 and 240 mmol Co₂·m^?2·d^?1, and there was a slight net dissolution of CaCO₃ (0.8 mmol · m^?2·d^?1). This site was a sink for atmospheric CO₂ (10 ± 4 mmol CO₂·m^?2·d^?1), and the analysis of data from the literature suggests that this is a general feature of algal-dominated reefs. Measurement of air-sea CO₂ fluxes in open water close to the enclosure demonstrated that changes in small-scale hydrodynamics can lead to misleading conclusions. Net CO₂ evasion to the atmosphere was measured on the fringing reef due to changes in the current pattern that drove water from the barrier reef (a C0₂ source) to the study site.     

A STERILIZATION PROTOCOL FOR THE DICTYOTALES (PHAEOPHYCEAE)1

Following a study on the effect of several physical (brushing and ultrasound) and chemical (antiseptic and antibiotic) treatments on the brown seaweed Stypopodium zonale (Lamoroux) Papenfuss (Dictyotales, Phaeophyceae), bactericidal treatments that were not phytotoxic to the alga were selected. The sterilization protocol consisted of 1) surface brushing of the explants, 2) incubation in the antiseptic betadine (0.50%) for 5 min, and 3) incubation in an antibiotic mixture (650 mg · L^?1 kanamycin, neomycin, and penicillin G) for 48 h. The response of the material to the treatments was assessed by means of an oxygen electrode, and a bacterial test was performed to test bactericidal efficiency. The protocol rendered photosynthetically active axenic explants of S. zonale and other members of the order (e.g. Zonaria tournefortii(Lam.) Montagne).     

The Effects of Seaweed Secondary Metabolites on Biofouling

Antifouling activity is one poorly investigated property of seaweed natural products. To determine, in the field, whether seaweeds contain chemicals able to influence the settlement of fouling organisms, crude organic extracts from Stypopodium zonale, Dictyota menstrualis (Phaeophyceae) and Laurencia obtusa (Rhodophyceae) were incorporated at natural volumetric concentrations, into hard stable gels that served as substrata for fouling in the experiments. Fouling organisms settled at a significantly higher rate on plates treated with S. zonale extracts than on control gels, while settlement was strongly inhibited on gels containing L. obtusa extracts. Fouling on gels treated with the D. menstrualis extract was not significantly different from the fouling found on control gels. The findings suggest that the broad antifouling properties of the crude extract of L. obtusa inhibit the settlement of fouling as well as hinder the development of settled fouling species, thereby reducing the richness of species. The results imply that L. obtusa possibly harbours powerful agents that can be explored for the development of antifouling technology.     

Growth studies of macroalgae in a microcomputer-assisted spray cultivation system

Apical growth rates of Furcellaria lumbricalis (Huds.) Lamour. and Ahnfeltia plicata (Huds.) Fries (Gigartinales: Rhodophyceae), and Ascophyllum nodosum (L.) Le Jol. (Fucales: Phaeophyceae), were studied in spray culture, applying independent microcomputer systems for control, data-logging, and apical growth measurements. The system functioned with a minimum of maintenance. Sea-water temperature and light seemed to be more important for growth than nutrient supply under the prevailing conditions. Basal shoots (young, undivided parts of the plants close to the holdfast) of Furcellaria lumbricalis had growth rates three times higher than the apices (apical meristem on the distal end of mature plants) from the older parts of the thallus. For Ascophyllum nodosum apical growth rates of basal shoots, divided and undivided apices were similar. Whereas apical growth rate of A. nodosum was normal, the biomass yield was low. A. nodosum cultivated simultaneously in tanks and in continuous spray had similar growth rates. The spray cultivation technique facilitated control of the experimental conditions, and handling of the plants during the experimental work while excluding epiphytes.     

Kinetics of nitrate uptake by New Zealand marine macroalgae and evidence for two nitrate transporters in <Emphasis Type="Italic">Ulva intestinalis</Emphasis> L.

Kinetic constants were determined for nitrate uptake in three species, Pterocladiella capillacea (S.G. Gmelin) Santelices et Hommersand (Rhodophyceae, Gelidiales), Ulva intestinalis L. (Chlorophyceae, Ulvales) and Xiphophora chondrophylla (Turner) Montagne ex Harvey (Phaeophyceae, Fucales), of New Zealand macroalgae, with K _m values ranging from 10 to 17 μM and V _max values from 3 to 65 μmole g⁻¹ dry weight h⁻¹. There was no effect of ammonium on nitrate uptake by Pterocladiella capillacea or Xiphophora chondrophylla. Ammonium inhibited nitrate uptake by 40% in Ulva intestinalis from a site with relatively low seawater ammonium concentrations. In contrast, U. intestinalis from an ammonium-enriched site had lower rates of nitrate uptake that were insensitive to inhibition by ammonium. It is suggested that there are (at least) two transport systems for nitrate in U. intestinalis; a constitutive transporter, which is insensitive to ammonium, and a transporter that is sensitive to ammonium inhibition and down-regulation by ammonium; the implications of this for our understanding of macroalgal blooms is discussed. Handling editor: K. Martens