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.     

滇池外海藻类时空分布及其与环境因素间非线性相关分析

文章基于滇池外海监测数据(2014—2020), 分析了滇池外海不同区域间的藻类分布情况, 并运用最大信息系数(Maximal Information Coefficient, MIC)定量分析了滇池外海中环境因素与藻类间的非线性关系。主要结果如下: (1)滇池外海藻密度呈现明显的北高南低的趋势, 蓝藻在所有藻类中占绝对优势, 且主要在夏季表现出最高的藻类密度占比, 绿藻的藻类占比次于蓝藻但远高于其他藻类且在春季的藻类占比相对最高; (2)总体上藻类密度与结果变量存在明显的线性关系, 同时与原因变量间的非线性关系显著; (3)蓝藻的水质驱动因素主要为水温(MIC: 0.27, P<0.01)和氨氮(MIC: 0.22, P<0.01), 且相较于其他氮源, 氨氮对蓝藻的影响更大。绿藻的水质驱动因素主要为总磷(MIC: 0.27, P<0.01)和总氮(MIC: 0.21, P<0.01), 其他形态的氮对绿藻的影响可能较氨氮更强。在气象条件中, 蓝藻和绿藻主要受气温及辐射量的控制。     

Enriching marine macroalgae with eicosatetraenoic (arachidonic) and eicosapentaenoic acids by chilling

Summary Twelve macroalgae belonging to the Chlorophyta, Phaeophyta and Rhodophyta were collected from the Arabian Gulf. Field samples and samples that were first incubated at 5° C and 24° C in the light for 1 week were analysed for lipids and fatty acids. The lipid contents varied according to the macroalga and, within the Chlorophyta and Phaeophyta, some representatives accumulated more lipids at 5° C and others at 24° C. All samples of algae had similar lipid composition with only quantitative differences. The temperature did not have a common effect on the lipid composition of representative algae, although changes in the relative concentration of specific classes were recorded. The Phaeophyta and Rhodophyta were as a rule richer than the Chlorophyta in eicosatetranoic (20:4) and eicosapentaenoic (20:5) but poorer in linolenic (18:3) acids. In most of the algae, incubation at 5° C was associated with lowering the proportion of palmitic acid (16:0) in the total lipids, and, but only in the Phaeophyta and Rhodophyta, increasing the concentration of 20:4 and 20:5. These polyunsaturated fatty acids occurred in high levels in monogalactosyldiacylglycerols (MGDG) and digalactosyldiacylglycerols (DGDG) of the Phaeophyta and Rhodophyta but not the Chlorophyta, the MGDG and DGDG of which were rich in 18:3 and hexadecatrienoic acid (16:3). Offprint requests to: R. H. Al-Hasan     

Survival of seaweeds ingested by three species of tropical sea urchins from Brazil

Three species of sea urchins, Echinometra lucunter, Lytechinus variegatus, and Arbacia lixula, common on the southeastern coast of Brazil, were selected for experiments on seaweed survival after passage through their digestive tract. L. variegatus and E. lucunter have more than 80% of their diet composed of algae. C. 24% of the species of algae present in the digestive tract survived. A. lixula has only 29% of its diet composed by algae, but the survival rate of the algae is c. 50%.Although Rhodophyta represent 51% of the ingested algae, their survival rate in the faeces is only 19%, while the Chlorophyta, with a survival rate of 63%, comprise only about 26% of the diet. Most species of algae that survived ingestion were r-strategists.     

Note on the survival of algal resting cells during long-term maintenance in darkness and minimum lake bottom temperature. Comparison of Anabaena (cyanobacteria) and Haematococcus (volvocales)

Resting cell formation in algae and cyanobacteria is one of the strategies developed for withstanding adverse environmental conditions. This note informs about the different capacities of such resting cells to germinate after long-term dark preservation at 4 °C in Anabaena variabilis (Cyanobacteria, Cyanophyta) and Haematococcus lacustris (Chlorophyta, Volvocales).     

PHYTOPLANKTON DISTRIBUTION AND WATER QUALITY INDICES FOR LAKE MEAD (COLORADO RIVER)1

Phytoplankton samples were collected in Lake Mead 6 times from September 1970 to June 1971 for 8 stations at depths of 0, 3, 5, 10, 20, and 30 m. These samples were processed through a Millipore filter apparatus and 79 planktonic algae were identified. Algal divisions represented were Bacillariophyta, 42 species; Chlorophyta, 18; Cyanophyta, 9; Chrysophyta, 3; Cryptophyta, 3; Pyrrophyta, 2; and Euglenophyta, 2. Blue-green algae were dominant in late summer and fall; green algae, diatoms, and cryptomonads in winter; and green algae in spring. The early summer flora was best represented by the Chlorophyta, Cryptophyta, and Chrysophyta. Palmer's pollution-tolerant algae indices and Nygaard's indices were calculated from, phytoplankton data. These indices suggest eutrophic conditions in Lake Mead, especially for Boulder Basin.     

PHYLOGENETIC POSITION OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE) BASED ON SMALL SUBUNIT RIBOSOMAL RNA SEQUENCE DATA1

A small subunit ribosomal RNA (16S-like rRNA) in the hydrocarbon-rich microalga Botryococcus braunii Kützing (Chlorophyceae) was amplified using RNA polymerase chain reaction, and its sequence was determined. The sequence data of B. braunii were analyzed with those of several other algae in order to determine phylogenetic relationships among these algae. Phylogenetic analysis indicated B. braunii to be a member of the Chlorophyta and possibly related to Characium vacuolatum and Dunaliella parva.     

THE BENTHIC ALGAE OF SOUTHERN BAFFIN ISLAND. I. EPIPELIC COMMUNITIES IN RIVERS1

The epipelic algae found in 9 rivers of southern Baffin Island were investigated during the 1972 growing season. The overall assemblage consisted of 240 taxa, of which 200 belonged to the Bacillariophyta and, only 17 to the Chlorophyta. Members of the Bacillariophyta accounted for S7–100% by numbers and 44–100% by volume of the algae at most localities. The dominant taxa were Achnanthes kriegeri Krasske, A. marginulata Grun., and Tabellaria flocculosa (Roth.) Kütz. The Chlorophyta comprised. 0–7% by numbers and 0–30% by volume of the algae, with Cosmarium tinctum Ralfs, Cylindrocystis spp., and Mougeotia sp. being most common. The standing crop in the different rivers commonly exceeded 8 × 10⁶ cells/cm² (8 × 10⁹μ³/cm²), and a maximum growth rate of 3.2 × 10⁵ cells/cm²/day (3.2 × 10⁸μ/cm²/day) was observed. Temperature and light are considered important, factors in the regulation of algal numbers, while nutrient supply in the overlying water, grazing by herbivores, wave action, and flooding appeared to have little effect.     

Actin Phylogeny Identifies Mesostigma viride as a Flagellate Ancestor of the Land Plants

Green algae and land plants trace their evolutionary history to a unique common ancestor. This ``green lineage' is phylogenetically subdivided into two distinct assemblages, the Chlorophyta and the Streptophyta. The Chlorophyta includes the Chlorophyceae, Trebouxiophyceae, Ulvophyceae, and Prasinopohyceae, whereas the Streptophyta includes the Charophyceae plus the bryophytes, ferns, and all other multicellular land plants (Embryophyta). The Prasinophyceae is believed to contain the earliest divergences within the green lineage. Phylogenetic analyses using rDNA sequences identify the prasinophytes as a paraphyletic taxon that diverges at the base of the Chlorophyta. rDNA analyses, however, provide ambiguous results regarding the identity of the flagellate ancestor of the Streptophyta. We have sequenced the actin-encoding cDNAs from Scherffelia dubia (Prasinophyceae), Coleochaete scutata, Spirogyra sp. (Charophyceae), and the single-copy actin gene from Mesostigma viride (Prasinophyceae). Phylogenetic analyses show Mesostigma to be the earliest divergence within the Streptophyta and provide direct evidence for a scaly, biflagellate, unicellular ancestor for this lineage. This result is supported by the existence of two conserved actin-coding region introns (positions 20-3, 152-1), and one intron in the 5′-untranslated region of the actin gene shared by Mesostigma and the embryophytes. Received: 10 July 1997 / Accepted: 9 April 1998     

Non-siliceous algae in a five meter core from Lake Kinneret (Israel)

The composition and succession of non-siliceous algae, studied in a five meter core from Lake Kinneret (Israel), are described. Only Chlorophyta species were recorded, probably due to the standard palynological sample processing which was used. In the lower part of the core, from the bottom to 300 cm (interval 5500–2500 years B.P.), Botryococcus braunii was the only common alga. Relevant changes in algal diversity and abundance occur at 300 cm. Many species of green algae were recorded for the first time (Pediastrum, Scenedesmus, Coelastrum, etc.). These changes may be related to an increase in nutrient concentration as a consequence of cultural disturbance. In the interval 300-0 cm, a succession of Pediastrum species is followed. The recovered green algae are extant in the present plankton of Lake Kinneret. They also constitute an important part of the algae found in the profundal sediments today.     

Gibberellins as endogenous growth regulators in green and brown algae

Summary Gibberellin-like activity was detected in extracts from Enteromorpha prolifera (Chlorophyta) and Ecklonia radiata (Phaeophyta). Material eluted from chromatograms of extracts and active in dwarf maize also brought about growth responses in the species from which the extract had been made. The responses were similar to those brought about by gibberellic acid. It is concluded that gibberellins are normally involved in regulating growth in green and brown algae.     

A clade uniting the green algae Mesostigma viride and Chlorokybus atmophyticus represents the deepest branch of the Streptophyta in chloroplast genome-based phylogenies

Background  

The Viridiplantae comprise two major phyla: the Streptophyta, containing the charophycean green algae and all land plants, and the Chlorophyta, containing the remaining green algae. Despite recent progress in unravelling phylogenetic relationships among major green plant lineages, problematic nodes still remain in the green tree of life. One of the major issues concerns the scaly biflagellate Mesostigma viride, which is either regarded as representing the earliest divergence of the Streptophyta or a separate lineage that diverged before the Chlorophyta and Streptophyta. Phylogenies based on chloroplast and mitochondrial genomes support the latter view. Because some green plant lineages are not represented in these phylogenies, sparse taxon sampling has been suspected to yield misleading topologies. Here, we describe the complete chloroplast DNA (cpDNA) sequence of the early-diverging charophycean alga Chlorokybus atmophyticus and present chloroplast genome-based phylogenies with an expanded taxon sampling.     

Epibiotic macroalgae on the scallop <Emphasis Type="Italic">Mizuhopecten yessoensis</Emphasis> in Peter the Great Bay,Sea of Japan

The composition and structure of the epibiotic flora of the Japanese scallop Mizuhopecten yessoensis were studied on the basis of data from long-term (1979 to 2007) observations on the scallop beds in Peter the Great Bay (Sea of Japan). In all, 52 species of macroalgae belonging to three phyla were found on the scallop shells; 3 species were new records for the benthic flora of the area studied. Red algae constituted the bulk of the species richness of algal epibionts; brown algae were represented by the lowest number of species. Species of Chlorophyta predominated in terms of biomass; species of Rhodophyta were found in lower numbers. The main form of the thallus of epibiotic algae was bushy or filamentous. The ratio of common to rare species was 30 : 70. As compared to the benthic flora, the epibiotic flora on the scallop shells was characterized by a greater number of warm-water species.     

Isolation of protoplasts from edible seaweeds

Protoplasts were isolated enzymatically from three species of Chlorophyta (Enteromorpha linza, Monostroma zostericola andUlva pertusa) with high yield and viability. An enzyme solution appropriate for protoplast isolation from the marine green algae was the following: 2% Cellulase Onozuka R-10, 1.0.M mannitol, pH 6.0. Protoplasts could not be obtained from members of Phaeophyta or Rhodophyta.     

Red-coloured snow algae in svalbard — Some environmental factors determining the distribution of Chlamydomonas nivalis (Chlorophyta volvocales)

Summary Studies of colonization of snow slopes by the snow algae Chlamydomonas nivalis (Chlorophyta volvocales) show that various environmental factors can be correlated with regions of algal colonization. All colonized sites discovered faced west, and when transects were made across the slopes it was found that areas of maximum colonization showed minima in temperature and pH and maxima of conductivity and chloride ion concentration.Svalbard Expedition (1980) Perse School, Cambridge     

Effects of plant harvesting and nutrient enrichment on phytoplankton community structure in a shallow urban lake

The utility of shallow water bodies in urban environments is frequently compromised either by dense beds of submerged plants or cyanobacterial blooms associated with nutrient enrichment. Although submerged plants are often harvested to facilitate recreational uses, this activity may alter the phytoplankton community, which in turn, also may restrict the use of the lake. We tested whether (i) plant harvesting reduced the abundance of flagellate algae and increased the abundance of cyanobacteria, and (ii) whether increasing levels of nutrient enrichment caused shifts in the dominance of heterocytous cyanobacteria, non-heterocytous cyanobacteria and Chlorophyta, in a shallow urban lake in Southern Australia as has been observed for shallow Danish lakes in previous studies. These predictions were tested with large (3000 l), replicated mesocosms in a warm, highly productive, shallow lake densely colonised by the submerged angiosperm, Vallisnaria americana Michaux. The heterokont algae, Chlorophyta, Cyanobacteria and Cryptophyta were the most numerous algal divisions in the lake. The Euglenophyta, although uncommon in early summer, became more abundant towards the end of summer. The Dinophyta and Charophyta were rare. The abundance of the heterokont algae and Euglenophyta was significantly reduced by plant harvesting even after plants had partially re-established 18 weeks after initial harvesting. The decline in the Euglenophyta in response to plant harvesting is consistent with earlier findings, that the relative abundance of flagellate algae tends to be greater in the presence of submerged plants. Contrary to our prediction, we found that the Cyanobacteria did not increase in response to plant harvesting, however the response may be altered under higher nutrient levels. Algal responses to nutrient enrichment in the presence of dense V. americana plants generally followed the patterns observed in shallow Danish lakes despite the large differences in climatic conditions. Both studies found that the abundance of heterocytous cyanobacteria declined at higher levels of nutrient enrichment, whereas non-heterocytous cyanobacteria and chlorophytes increased.     

Relative availability and utilization of algae in two subarctic rivers

The ash free dry weight of algae in the plankton, epilithon and gut of predominant herbivores was determined between June 1975 and July 1976 in 2 subarctic Canadian rivers (Baker Creek, Yellowknife River). Algae usually represented < 1% of suspended solids in both rivers and up to 8o% of material attached to rocks. While they were never found in the gut of rotifers and copepod nauplii in Baker Creek, they accounted for 0.5% of the contents of the planktonic conchostracon Lynceus brachyurus. Due to the inpalatable colonial structure of most attached algal species, the zoobenthos (mainly mayfly nymphs) contained only a few cells. Size selection against large fragments of detritus resulted in increased consumption of algae (5–13%) by Simulium venustum, S. decorum and S. arcticum. In the Yellowknife River, Diaptomus ashlandi (CIII–CVI stages) and Holopedium gibberum contained only a few (30–50) algal cells during summer. Because of size selection, large algae were not ingested by these species. The inpalatability of colonial algae greatly reduced consumption in the predominant zoobenthic species, Ephemerella coxalis and E. margarita. While all species digested diatoms, the Chlorophyta usually passed through the gut unharmed. It is concluded that algae are not an important energy source for invertebrates in either stream.     

Meteorological effects on variation of airborne algae in Mexico

Sixteen species of algae were collected from 73.8 m³ of air. Eleven were obtained in Minatitlán and eleven in México City. The data show that similar diversity occurred between the two localities, in spite of the difference in altitude. This suggests that cosmopolitan airborne microorganisms might have been released from different sources. Three major algal divisions (Chlorophyta, Cyanophyta and Chrysophyta) formed the airborne algal group. Also, a large concentration of 2220 algae m^–3 was found near sea-level, while lower amounts were recorded at the high altitude of México City. The generaScenedesmus, Chlorella andChlorococcum dominated. Striking relationships were noted between the concentration of airborne green and blue-green algae, and meteorological conditions such as rain, vapour pressure, temperature and winds for different altitudes. In Minatitlán a linear relationship was established between concentration of algae and both vapour pressure (mbar) and temperature (° C), while in México City the wind (m s^–1) was associated with variations in the algal count.     

DISTINGUISHING MULTIPLE LINEAGES OF PEDIASTRUM DUPLEX WITH MORPHOMETRICS AND A PROPOSAL FOR LACUNASTRUM GEN. NOV1

Accurately defining species boundaries in the green algae (Chlorophyta) is integral for studies of biodiversity and conservation, water‐quality assessments, and the use of particular species as paleoindicators. Recent molecular phylogenetic and SEM analyses of the family Hydrodictyaceae (Chlorophyta) resolved three phylogenetic lineages of isolates with the Pediastrum duplex Meyen 1829 phenotype. The present study employed analyses of cell shape and cell wall ultrastructure to determine if the three lineages possessing the P. duplex morphotype were distinguishable. Only one of the groups, containing isolates with the P. duplex var. gracillimum West et G. S. West phenotype, was shown to be morphologically distinct from the other two P. duplex groups. The erection of a new genus, Lacunastrum, is proposed to recognize this group as a separate taxon.     

Antimicrobial activity of some macroalgae of the Veracruzano Reef System (SAV), Mexico

The study of macroalgae antimicrobial agents is limited to Mexico and scarce in the Veracruzano Reef System (SAV). It is necessary to devote efforts towards this field of applied phycology. The aim was to evaluate the antimicrobial activity of some phyla of Rhodophyta, Chlorophyta and Ochrophyta from SAV. Methanolic extracts from 23 marine macroalgae species (7 Chlorophyta, 4 Phaeophyta and 12 Rhodophyta) from the Veracruzano Reef System (SAV) (Mexico) were evaluated for antimicrobial activity. Antibacterial and antifungal activity were assessed by agar diffusion and agar dilution methods. The differences between mean values obtained for experimental groups was done by analysis of variance (ANOVA multifactorial model), p-values of 0.001 or less were considered statistically significant. Two new records are recognized for SAV (Laurencia gracilis and Sebdenia flabellata) and Compsothamnion thuioides for the Gulf of Mexico coasts. 16 species showed antibacterial activity, of which Caulerpa sertularioides, Ulva lactuca and Laurencia obtuse had significant activity on Gram-positive bacteria. 43.7% belong to the phyla Chlorophyta (7 species), 50% Rhodophyta (8 species) and 6.25% Ochrophyta (1 species). This indicates that the extracts of the algae of the Rhodophyta and Chlorophyta are the ones that showed the greatest activity. Regarding the yeasts, 16.6% of the total algae collected were active in the different yeast strains. 43.7% belongs to Chlorophyta species and for Rhodophyta were 60%. The macroalgae with the highest antifungal activity were: Cymopolia barbata, Ulva lactuca and Laurencia gracilis. The macroalgae of the Veracruzano Reef System present antimicrobial activity. This study is the first investigation of macroalgae's bioactive components from SAV, where they could be sources for future medical applications.