Screening and preliminary characterization of hemagglutinins in Vietnamese marine algae

Extracts from 44 species of Vietnamese marine algae, including 15 Chlorophyta, 18 Rhodophyta and 11 Phaeophyta species, were examined for hemagglutination activity with a variety of different animal and human erythrocytes that were untreated or treated with enzymes. Almost all extracts showed activity toward at least one type of erythrocytes, although those from three Chlorophyta and two Rhodophyta species showed no hemagglutination with any type of erythrocytes examined. Strong activity was detected in extracts from two Chlorophyta (Anadyomene plicata and Avrainvillea erecta) and four Rhodophyta species (Gracilaria eucheumatoides, Gracilaria salicornia, Kappaphycus alvarezii, and Kappaphycus striatum) with enzyme-treated rabbit and sheep erythrocytes. The hemagglutinins of seven Chlorophyta and eight Rhodophyta species were examined for sugar-binding specificity, pH- and temperature-stability, and divalent cation-independency of hemagglutination using ammonium sulfate-precipitates prepared from their extracts. In a hemagglutination-inhibition test with various monosaccharides and glycoproteins, none of the hemagglutinins had affinity for monosaccharides, except the Codium arabicum and Gracilaria euchematoides hemagglutinins, whose activities were inhibited by both N-acetyl-d-galactosamine and N-acetyl-d-glucosamine. On the other hand, all of the hemagglutinins activities were inhibited by some glycoproteins. The inhibition profiles with glycoproteins were different depending on hemagglutinin species, and suggest the presence of lectins specific for high mannose N-glycans, complex N-glycans, or O-glycans. The activities of these algal hemagglutinins were stable over a wide range of pH and temperature, and independent of the presence of divalent cations. These results indicate that Vietnamese marine algae are a good source of novel and useful lectins.     

Quaternary marine macroalgae from Greenland

Four species of brown algae, Sphacelaria arctica, S. plumosa, Desmarestia aculeata , and midribs of a Fucus species have been found in Holocene and interstadial deposits in Greenland. The green alga Chlorochytrium dermatocolax and the red alga Audoui-nella cfr. microscopica are reported for the first time in such deposits. All species are present in the extant flora of marine, benthic algae from Greenland. They are very well preserved and can be identified to species level.     

Lipoxygenase inhibitors derived from marine macroalgae

The solvent extracts from the algae Sargassum thunbergii (Sargassaceae) and Odonthalia corymbifera (Rhodomelaceae) were subjected to soybean lipoxygenase inhibitory screening. Two hydrophobic inhibitors were obtained from the extracts of S. thunbergii through inhibitory assay-guided fractionation. The inhibitors were identified as known exo-methylenic alkapolyenes (6Z,9Z,12Z,15Z)-1,6,9,12,15-henicosapentaene (1) and (6Z,9Z,12Z,15Z,18Z)-1,6,9,12,15,18-henicosahexaene (2). The alkapolyenes 1 and 2 showed higher inhibitory activity than the known inhibitor nordihydroguaiaretic acid (NDGA). Pheophytin a (3) was obtained from the extract of O. corymbifera. The inhibitor 3 also showed higher inhibitory activity than NDGA. This is the first report on lipoxygenase inhibition of exo-methylenic alkapolyenes and a chlorophyll a-related substance.     

Fungal community associated with marine macroalgae from Antarctica

Filamentous fungi and yeasts associated with the marine algae Adenocystis utricularis, Desmarestia anceps, and Palmaria decipiens from Antarctica were studied. A total of 75 fungal isolates, represented by 27 filamentous fungi and 48 yeasts, were isolated from the three algal species and identified by morphological, physiological, and sequence analyses of the internal transcribed spacer region and D1/D2 variable domains of the large-subunit rRNA gene. The filamentous fungi and yeasts obtained were identified as belonging to the genera Geomyces, Antarctomyces, Oidiodendron, Penicillium, Phaeosphaeria, Aureobasidium, Cryptococcus, Leucosporidium, Metschnikowia, and Rhodotorula. The prevalent species were the filamentous fungus Geomyces pannorum and the yeast Metschnikowia australis. Two fungal species isolated in our study, Antarctomyces psychrotrophicus and M. australis, are endemic to Antarctica. This work is the first study of fungi associated with Antarctic marine macroalgae, and contributes to the taxonomy and ecology of the marine fungi living in polar environments. These fungal species may have an important role in the ecosystem and in organic matter recycling.     

Ichtyotoxic activity of extracts from Mexican marine macroalgae

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allelochemistry in marine macroalgae

Allelochemistry refers to the effect of an organic compound released from one organism upon an organism separated from its source. When the donor and receptor are plants (or microorganisms placed in the plant kingdom), allelopathy is described whether the effect is harmful or beneficial. In the aquatic environment, water disperses any water‐soluble allelochemical from its point of release, and rapid dilution along with lack of contact between competing organisms reduces potential encounter. This review centers on macroalgae as the source of allelochemicals. In all examples, the releasor organism is a macroalga, but receptor organisms include algae, invertebrates, fish, and microbes. Direct evidence in the sea is scanty, and there is a need for appropriate experiments in the laboratory and field. The compounds that are released by macrolagae (e.g., polyphenolics, halogenated phenols, and terpenoids) may be fortuitous byproducts of metabolism. But where they alter colonization, growth, or reproduction in a target organism, it is conceivable that they influence community structure as is known for terrestrial systems. The potential for allelochemistry is maximized in sites where water is poorly mixed, allowing released algal products to concentrate (e.g., tide pools and backbays) and where the receptor organism is adjacent to the releasor (e.g., surfaces of thalli and seaweed farms). In combination with restricting environmental conditions (e.g., critical temperature, light, salinity, pH, or oxygen), the effect of allelopathy can be synergistic. Combinations of allelochemicals, each at a concentration too low to be physiologically effective, could have a pronounced impact.     

Agglutinins from marine macroalgae of the southeastern United States

Protein extracts from 22 species of marine macroalgae from Florida and North Carolina were compared for their abilities to agglutinate sheep and rabbit erythrocytes. Protein extracts from 21 algal species agglutinated rabbit erythrocytes compared to 19 for sheep erythrocytes. However, agglutination by brown algal extracts was variable. The agglutination produced by protein extracts from Dictyota dichotoma could be blocked by addition of polyvinylpyrrolidone. Protein extracts from North Carolina macroalgae were also tested against five bacterial species. Three of these agglutinated bacterial cells. Ulva curvata and Bryopsis plumosa agglutinated all five species. Protein extracts from five species of Florida algae were tested for their effects on mitogenesis in mouse splenocytes and human lymphocytes. Gracilaria tikvahiae HBOI Strain G-5, Ulva rigida and Gracilaria verrucosa HBOI Strain G-16S stimulated mitogenesis in mouse splenocytes, while Gracilaria tikvahiae HBOI Strain G-16stimulated mitogenesis in human lymphocytes.     

Vanadium an essential element for some marine macroalgae

In some marine algae cultivated axenically in the artificial medium ASP6 F2 (pH 8.3) vanadium at 1–100 g l^-1 increases the fresh weight. In the multicellular brown algaFucus spiralis 10 g V I^-1 enhances the fresh weight by about 400% while in the green algaEnteromorpha compressa the yield is increased by 90%. Red algae do not respond to vanadium. InFucus morphological effects are displayed in more frequent branching and/or broader blades. No significant increase in the chlorophyll content could be demonstrated at the early stage at which these morphological effects first appeared. Later the chlorophyll content increased.     

New records of temperate and sub-Antarctic marine benthic macroalgae from Antarctica

 During visits to several localities on the South Shetland Islands and the Antarctic Peninsula in summer 1994 we made collections of marine benthic algae. Among the algae we collected were three new records for Antarctica [Petalonia fascia (OF Müller) Kuntze; Enteromorpha intestinalis (L.) Nees; Rhodymenia subantarctica Ricker] and seven other species [Scytosiphon simplicissimus (Clemente) Cremades; Chordaria linearis (Hooker et Harvey) Cotton; Halopteris obovata (Hooker et Harvey) Sauvageau; Acrosiphonia arcta (Dillwyn) J. Agardh; Enteromorpha compressa (L.) Nees; Bangia atropurpurea (Roth) C. Agardh; Porphyra plocamiestris Ricker] that had been reported on only one or two previous occasions (or, in one case, three). The ten species detailed in this paper fall into two groups: four species previously known from sub-Antarctic islands and/or locations in southern South America, and six species having a wider distribution in temperate regions. We discuss the possibility that the less accessible subtidal habitats of some species may have prevented earlier discovery. Other species may be comparatively recent adventives, most likely introduced with shipping. In view of possible global climate changes, species of this latter group are regarded as suitable organisms for monitoring changes of water temperature. Received: 12 December 1995/Accepted: 14 April 1996     

Fatty acids from 11 marine macroalgae of the French Brittany coast

Four species of red marine algae (Rhodophyceae), five species of brown marine algae (Pheophyceae) and two species of green marine algae (Chlorophyceae) were examined for the fatty acid composition of the three lipid groups separated by silica gel column chromatography (neutral lipids, glycolipids, phospholipids). The four red algae had high contents of 16:0 and C20-polyunsaturated fatty acids (PUFA), 20:5n-3 ranging from 18 to 49% of the total fatty acid content and 20:4n-6 from 1.4 to 22.5%, these fatty acids were evenly distributed in all lipid groups. The five brown algae had high contents of 18:1n-9, 18:2n-6 and 18:3n-3 but low content of 20:5n-3. No precise trend was detected for the distribution of these fatty acids in the three lipid groups. The two green algae had high contents of 16:0, 18:1n-7 and 18:3n-3 and a very low content of PUFA. They contained also large amounts of 16:4n-3 together with 16:2n-6 and 16:3n-3. While 16:2n-6 was mainly found in phospholipids, 16:4n-3 was mainly distributed in neutral lipids and glycolipids.Porphyra umbilicalis represents the richest source of 20:5n-3 whileUndaria pinnatifida can be selected when a balanced mixture of (n-6) and (n-3) PUFA is required.Author for correspondence     

Primary structures of two hemagglutinins from the marine red alga, Hypnea japonica

As the first examples among marine algal hemagglutinins, the primary structures of two hemagglutinins, named hypnin A-1 and A-2, from the red alga Hypnea japonica, were determined by Edman degradation. Both hemagglutinins were single-chain polypeptides composed of 90 amino acid residues including four half-cystines, all of which were involved in two intrachain disulfide bonds, Cys(5)-Cys(62) and Cys(12)-Cys(89). Hypnin A-1 and A-2 had calculated molecular masses of 9146.7 and 9109.7 Da which coincided with determined values, 9148 and 9109 Da, by electrospray ionization-mass spectrometry, respectively. Both hemagglutinins only differed from each other at three positions; Pro(19), Arg(31) and Phe(52) of hypnin A-1 as compared with Leu(19), Ser(31), and Tyr(52) of hypnin A-2. Approximately 43% of total residual numbers consisted of three kinds of amino acids: serine, glycine and proline. The hemagglutination activities were lost by reduction and alkylation of the disulfide bonds. The nature of the small-sized polypeptides, including disulfide bonds, may contribute to the extreme thermostability of the hemagglutinins. Sequence having overall similarity to hypnin A-1 or A-2 was not detected in databases. Unexpectedly, however, hypnins contained a motif similar to the alignment of the C-terminal conserved amino acids within carbohydrate-recognition domains of C-type animal lectins. Furthermore, interestingly, the hemagglutination activities were inhibited by a protein, phospholipase A-2 besides some glycoproteins, suggesting that hypnins may possess both a protein-recognition site(s) and a carbohydrate-recognition site(s).     

The macromolecular composition of noncalcified marine macroalgae

The macromolecular composition of macroalgae influences nutrient flow and food quality in aquatic ecosystems and the value of macroalgae species for human consumption, aquaculture, biofuels, and other applications. We used literature data (125 publications, 1,117 observations) and a hierarchal Bayesian statistical model to estimate the average macromolecular composition, protein, lipid, and carbohydrate of macroalgae as a whole and at the phylum level. Our focus was on marine, noncalcified macroalgae sampled from wild‐grown populations in the field. We found that the median macromolecular composition is 9.98% protein, 2.7% lipid, 48.5% carbohydrate, and 31.8% ash as percent dry weight. We compared the median macromolecular content of macroalgae to microalgae and herbaceous plants and test for differences in macromolecular content across macroalgal phyla. Macroalgae were much more enriched in carbohydrate and minerals than the microalgae and lower in protein and lipid than many herbaceous plants. Rhodophyte macroalgae have significantly less lipid and more protein and the Ochrophyte macroalgae have significantly less protein than the average.     

Responses of marine macroalgae to hydrogen-peroxide stress

In this study, we determined the antioxidative potential of 15 marine macroalgae by measuring the photosynthetic efficiency under artificial oxidative stress after a 30-min exposure to a series of ascending H₂O₂ concentrations. Species exhibiting high maximum quantum yields (F_v/F_m values) were regarded as not susceptible towards H₂O₂ stress. In addition to the short-term stress experiments, the antioxidative defense systems (enzymatic and non-enzymatic) of selected algal species under longer exposure times to H₂O₂ were investigated.Species with striking photosynthetic activity under H₂O₂ stress were Chaetomorpha melagonium (Chlorophyta), showing 40% reduced F_v/F_m as compared to the control after 8 days of exposure to 20 mM H₂O₂. In Fucus distichus (Phaeophyta) F_v/F_m decreased to 50% of the control under the same exposure conditions. Polysiphonia arctica (Rhodophyta) exhibited highest F_v/F_m values with a reduction of only 25%, therefore possessing the highest antioxidative potential of the investigated species.In P. arctica the activities of the antioxidative enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as the pool size of the antioxidant ascorbic acid were investigated. When exposed to different H₂O₂ concentrations (0-2 mM) over 6 days, the intrinsic activities of SOD and GR were stimulated. In a kinetic study over 8 days, the activity of antioxidative enzymes APX and CAT as well as ascorbic acid content were recorded. APX activity was much higher in H₂O₂-treated thalli at the end of the experiment than in the control, also CAT activity increased significantly with increasing H₂O₂ stress. In parallel, ascorbic acid content was reduced under high H₂O₂ concentrations. Furthermore, by using GC-MS techniques in P. arctica bromophenolic compounds with antioxidative properties were identified.This study shows that the measurement of the in vivo fluorescence of photosystem II is a suitable tool to determine the effect of oxidative stress on macroalgae. From these studies it is obvious that different algal species have varying strategies against oxidative stress which correlate with zonation on the shore.     

Using marine macroalgae for carbon sequestration: a critical appraisal

There has been a good deal of interest in the potential of marine vegetation as a sink for anthropogenic C emissions (“Blue Carbon”). Marine primary producers contribute at least 50% of the world’s carbon fixation and may account for as much as 71% of all carbon storage. In this paper, we analyse the current rate of harvesting of both commercially grown and wild-grown macroalgae, as well as their capacity for photosynthetically driven CO₂ assimilation and growth. We suggest that CO₂ acquisition by marine macroalgae can represent a considerable sink for anthropogenic CO₂ emissions and that harvesting and appropriate use of macroalgal primary production could play a significant role in C sequestration and amelioration of greenhouse gas emissions.     

A new hemogregarine from marine fishes.

Haemogregarina uncinata sp. n. is described from the blood of 2 marine eelpouts, Lycodes lavalaei and Lycodes vahlii (Perciformes: Zoarcidae). Erythrocytic schizogony occurred in peripheral and cardiac blood, but mature schizonts were restricted to the latter site. Mature and rupturing schizonts contained 10 to 30 merozoites, which were short and thick in small schizonts while slender and long in larger schizonts. Gametocytes developed in mature erythrocytes and displayed morphologic and morphometric characters that distinguished them from other species described. Syzygy and gamete formation occurred in the gut of a leech, Johanssonia sp. Each microgametocyte produced up to 4 apparently nonflagellated gametes. Oocysts developed intracellularly in the epithelial wall of the intestine and at maturity produced under 100 sporozoites from (apparently) several germinal centers. Sporozoites subsequently migrated to the probosces of the leeches. The failure to transmit the parasite to a sculpin (Myoxocephalus octodecemspinosus) and 3 Atlantic cod (Gadus morhua) via regurgitation by the leeches might be indicative of host specificity.     

A new species ofEupenicillium from marine sediment

A new species ofEupenicillium isolated from marine sediment,Eupenicillium limosum, is described and illustrated. This species is characterized by subglobose ascospores with spinulose surface ornamentation and irregular biverticillate penicilli.     

Hydrogen and volatile fatty acids production from marine macroalgae by anaerobic fermentation

Hydrogen and volatile fatty acids (VFAs) were coproduced from marine macroalgae by anaerobic fermentation using a microbial community. The hydrogen and VFAs production were characterized based on inoculum heat-treatment, methanogen inhibitor addition, operating temperature, and in-situ extraction of VFAs. Maximum hydrogen of 179 mL/g-VS and VFAs concentration of 9.8 g/L were produced from 35 g/L of S. japonica within 5 days of anaerobic fermentation. Hydrogen and VFAs yields were well-correlated with carbohydrate content of substrate. Inoculum heat-treatment significantly improved hydrogen production while the VFAs productivity was affected adversely. The addition of methanogen inhibitors also enhanced the hydrogen production, but the effect on VFAs production was dependent on the type of inhibitor used. Low temperature (25°C) was found to be favorable for high hydrogen and VFAs yield, while high temperature (40°C) and programmed-temperature (35 ~ 45°C) were more favorable for hydrogen and VFAs productivity. Clostridium sp. content was found to be the most abundant at 25°C. An extractive fermentation with anion-exchange resin was tested to recover the VFAs and to control the pH during the anaerobic fermentation.     

Antioxidant activities in tropical marine macroalgae from the Yucatan Peninsula,Mexico

Extracts from 48 marine macroalgae species (17 Chlorophyta, 8 Phaeophyta and 23 Rhodophyta) from the coasts of Yucatan and Quintana Roo (Mexico) were evaluated for antioxidant activity. The antioxidant activity was measured with the DPPH (2,2-diphenyl-1-picrylhydrasyl) method, and the phenolic content of each extract were also evaluated. All species exhibited a DPPH radical scavenging activity, and three species (Avrainvillea longicaulis, Chondria baileyana and Lobophora variegata) demonstrated great antioxidant potential with very low oxidation index EC₅₀ (1.44 ± 0.01, 2.84 ± 0.07 and 0.32 ± 0.01 mg mL⁻¹, respectively), significantly equivalent to EC₅₀ of some commercial antioxidants such as α-tocopherol, ascorbic acid, BHA and BHT. Moreover, extracts of the most active species exhibited reducing activities, superoxide anion radical scavenging and inhibition of lipid peroxidation. These results suggest that some macroalgae from the Yucatan peninsula have a great antioxidant potential which could be considered for future applications in medicine, food production or cosmetic industry.     

The characteristics of bio-oil produced from the pyrolysis of three marine macroalgae

The pyrolysis of two brown macroalgae (Undaria pinnatifida and Laminaria japonica) and one red macroalgae (Porphyra tenera) was investigated for the production of bio-oil within the temperature range of 300-600°C. Macroalgae differ from lignocellulosic land biomass in their constitutional compounds and high N, S and ash contents. The maximum production of bio-oil was achieved at 500°C, with yields between 37.5 and 47.4 wt.%. The main compounds in bio-oils vary between macroalgae and are greatly different from those of land biomass, especially in the presence of many nitrogen-containing compounds. Of the gaseous products, CO(2) was dominant, while C(1)-C(4) hydrocarbons gradually increasing at 400°C and above. The pretreatment of macroalgae by acid washing effectively reduced the ash content. The pyrolysis of macroalgae offers a new opportunity for feedstock production; however, the utilization of bio-oil as a fuel product needs further assessment.     

Evaluation of pyrolysis chars derived from marine macroalgae silage as soil amendments

Pyrolysis char residues from ensiled macroalgae were examined to determine their potential as growth promoters on germinating and transplanted seedlings. Macroalgae was harvested in May, July and August from beach collections, containing predominantly Laminaria digitata and Laminaria hyperborea; naturally seeded mussel lines dominated by Saccharina latissima; and lines seeded with cultivated L. digitata. Material was ensiled, pressed to pellets and underwent pyrolysis using a thermo‐catalytic reforming (TCR) process, with and without additional steam. The chars generated were then assessed through proximate and ultimate analysis. Seasonal changes had the prevalent impact on char composition, though using mixed beach‐harvested material gave a greater variability in elements than when using the offshore collections. Applying the char at 5% (v/v)/2% (w/w) into germination or seedling soils was universally negative for the plants, inhibiting or delaying all parameters assessed with no clear advantage in harvesting date, species or TCR processing methodology. In germinating lettuce seeds, soil containing the pyrolysis chars caused a longer germination time, poorer germination, fewer true leaves to be produced, a lower average plant health score and a lower final biomass yield. For transplanted ryegrass seedlings, there were lower plant survival rates, with surviving plants producing fewer leaves and tillers, lower biomass yields when cut and less regrowth after cutting. As water from the char‐contained plant pots inhibited the lettuce char control, one further observation was that run‐off water from the pyrolysis char released compounds which detrimentally affected cultivated plant growth. This study clearly shows that pyrolysed macroalgae char does not fit the standard assumption that chars can be used as soil amendments at 2% (w/w) addition levels. As the bioeconomy expands in the future, the end use of residues and wastes from bioprocessing will become a genuine global issue, requiring consideration and demonstration rather than hypothesized use.