β-d-(1→4), β-d-(1→3) ‘mixed linkage’ xylans from red seaweeds of the order Nemaliales and Palmariales

Xylans from five seaweeds belonging to the order Nemaliales (Galaxaura marginata, Galaxaura obtusata, Tricleocarpacylindrica, Tricleocarpa fragilis, and Scinaia halliae) and one of the order Palmariales (Palmaria palmata) collected on the Brazilian coasts were extracted with hot water and purified from acid xylomannans and/or xylogalactans through Cetavlon precipitation of the acid polysaccharides. The β-d-(1→4), β-d-(1→3) ‘mixed linkage’ structures were determined using methylation analysis and 1D and 2D NMR spectroscopy. The presence of large sequences of β-(1→4)-linked units suggests transient aggregates of ribbon- or helical-ordered structures that would explain the low optical rotations.     

Karyology and agar analysis of the agarophyteGelidiella acerosa (Forsskål) Feldmannet Hamel from the Philippines

Microspectrophotometry with the DNA-localizing fluorochrome DAPI demonstrated ploidy level differences in tetrasporophytic and presumptive gametophytic phases ofGelidiella acerosa from the Philippines. Comparison of mean nuclear DNA (I _f ) values to chicken erythrocytes (RBC) resulted in an estimate of 0.32 pg/2 C genome. Karyological studies with aceto-orcein revealed a chromosome complement of six bivalents during diakinesis of tetrasporocytes. The agar yield ranges from 13–24% dry weight, depending on the method of extraction. Agar extraction in 1 N NaOH resulted in an increased gel strength of 189 g cm^–2 at 1.5% concentration. Infrared spectroscopy indicated a relatively high sulfate content in native agar. The low (61 °) melting temperature is indicative of high sulfation and small molecular size.     

Implementation of a new index to assess intertidal seaweed communities as bioindicators for the European Water Framework Directory

An index CCO (cover, characteristic species, opportunistic species) has been developed for the implementation of the European Water Framework Directory (WFD) in coastal waters, using intertidal macroalgal communities as bio-indicator (Biological Quality Element). CCO is based on the calculation of three metrics corresponding to the global cover of macroalgal communities (metric 1), the number of characteristic species per topographic level/seaweed community (metric 2) and the cover of opportunistic species (metric 3). The final rating is obtained by pooling the scores of the three metrics. Results are given for 32 sites in 29 water bodies, grouped into four biogeographic regions along the Channel–Atlantic coasts of France. Over the six-year study, most of sites were sampled twice each (every three years). CCO index revealed that 25 coastal water bodies of both the Channel and the Bay of Biscay were in good or high ecological quality status (EQS), whereas only 4 of them were moderate and none in poor to bad status. However, significant differences have been found between sites and between geographic regions, water bodies located in Brittany obtaining the best EQS. No significant change occurred between the three-year sampling sets. A significant correlation has been established between a three-component anthropogenic pressure index and CCO ratings, showing the accuracy of CCO to evaluate the impact of anthropic activities on the structure and development of macroalgal communities as indicator of the ecological quality of coastal water bodies.     

Isolation and cross‐species amplification of microsatellite loci from the fucoid seaweeds Fucus vesiculosus,F. serratus and Ascophyllum nodosum (Heterokontophyta,Fucaceae)

The Fucaceae is a family of brown seaweeds that dominate and frequently co‐occur on North Atlantic rocky shores. We developed nine polymorphic microsatellite markers for the fucoid seaweeds Fucus vesiculosus, F. serratus and Ascophyllum nodosum using a combined, enriched library. Six of these loci were polymorphic in at least two species, showing from two to eight alleles with heterozygosities ranging from 0.41 to 0.85. Loci were also tested on F. spiralis, revealing five polymorphic microsatellite loci in this species.     

海藻有性繁殖生态学研究进展

由于研究技术与方法的不断改进 ,人们对海藻 (seaweeds)早期生活史方面的研究兴趣日益增大。评述了近年来海藻有性繁殖过程中配子释放和受精生态学问题。到达一定生理状态的海藻 ,通过对环境暗示应答而诱导配子形成。海藻生殖器官感受另一些特定的环境条件 ,通过有关信号传递机制 ,触发配子释放。海藻配子释放的时间及其所需的环境条件 ,依不同的种类而变化。配子同步释放以及各种适当的环境条件提高了受精频率和受精成功率 ,有利于受精的各种生物的和非生物的因素组合 ,形成了“机会窗 (the window of opportunity)”的概念。近年来的研究表明 ,海藻 (特别是红藻 )的自然受精成功率比以前所认为的要高得多。受精后合子 (胚 )的散布、集落与附着显著地影响其生存以及种群动态。对今后值得进一步研究的方面作了展望     

The Bering Strait connection: dispersal and speciation in boreal macroalgae

A large number of boreal seaweeds have either sibling species or conspecific populations of a single species in the North Pacific and North Atlantic Oceans. This pattern is thought to have arisen from the dispersal between the two oceans through the Arctic Ocean after the opening of the Bering Strait in the mid-to-late Miocene or earliest Pliocene and from subsequent vicariant speciation as the Arctic Ocean froze and Bering Strait closed intermittently during glacial periods. Recent molecular studies of species in all three major seaweed phyla reveal patterns of vicariance. However, a number of lines of evidence point to differences in origins of these clades; some appear to be Pacific in origin whereas others appear to be derived from Atlantic stock. Different origins can be explained by recent stratigraphic finds that push the first Cenozoic opening of the Bering Strait back from 3.1–4.1 to 4.8–7.4 Ma (million years ago). Northern hemisphere ocean circulation models suggest that water flow would have been from the North Atlantic–Arctic south through the Bering Strait prior to the closure of the Panamanian Isthmus c. 3.5 Ma in contrast to the northward flow from the Pacific into the Arctic and North Atlantic, which developed after the closing of the Isthmus. Despite these differences in timing of the two invasions, there are no significant differences in levels of relationships among species with a North Atlantic origin compared with species with a North Pacific origin based on currently available data. More work is required to understand vicariance in seaweeds, especially in deciphering when a speciation event has occurred.     

Development of microsatellite markers in the green algae Enteromorpha intestinalis (Chlorophyta)

The fouling green algae Enteromorpha intestinalis is a cosmopolitan benthic species, which causes green tides in many coastal areas and is used as an indicator species for eutrophication in the Baltic Sea area. The life cycle of E. intestinalis alternates between two morphologically identical reproductive stages, a haploid gametophyte phase and a diploid sporophyte phase. However, it also reproduces through asexual propagation. The reproductive cycles of E. intestinalis in the Baltic Sea and elsewhere are largely unknown. Here we report five polymorphic microsatellite markers developed from enriched genomic libraries. The number of alleles per locus ranged from 7 to 25.     

Proteins of Brown Seaweeds as Inhibitors of Endo-1→3-β-D-glucanases of Marine Invertebrates

It has been found that aqueous–ethanol extracts of brown seaweeds contain substances inhibiting endo-13--D-glucanases, the digestive enzymes of marine mollusks. The inhibitors were detected in 14 of 21 brown seaweeds investigated. An irreversible protein inhibitor possessing high specificity toward endo-13--D-glucanases of marine mollusks was isolated from the brown seaweed Laminaria cichorioides. As determined by gel filtration, the molecular mass of the inhibitor is 46 kD. The value of [I]₅₀ (10^–8 M) for the inhibitor is comparable with the corresponding value for natural inhibitors of amylases from terrestrial plants. The results of chemical modification indicated that tryptophan, glutamic acid, aspartic acid, histidine, and probably tyrosine residues are important for the interaction of the inhibitor with the enzyme.(subject: to Zvyagintseva)     

Nutritional composition of edible Hawaiian seaweeds

Fresh seaweeds, both wild and cultivated,are commonly eaten as food in the HawaiianIslands. Before Western contact, limu (seaweed) was a regular part of thediet, and is thought to have contributedvitamins and essential mineral nutrientsnot found in other staple food items. Twenty-two species of edible Hawaiianmacroalgae (6 Chlorophyta, 4 Phaeophyta, 12Rhodophyta) were analyzed for protein,lipid, carbohydrate, ash, caloric, mineraland vitamin content. Halymeniaformosa and Porphyra vietnamensisranked highest in total protein contentamong the species analyzed. Most speciescontained less than 5% crude lipid,although two Dictyota species hadover 16% crude lipid based on dry weight. Soluble carbohydrates ranged from 4.5 to39.9% dry weight. Ash values ranged from22.4% to 64.2%. Dictyotasandvicensis and Monostromaoxyspermum had caloric content each over3000 cal g^-1 ash-free dry weight. Allspecies contained measurable quantities of11 essential mineral elements. The majorityof Hawaiian seaweeds tested contained-carotene (vitamin A), and Enteromorpha flexuosa contained thehighest amount of vitamin C (3 mg g^-1).     

Remediation of complex remazol effluent using biochar derived from green seaweed biomass

Abstract

The unique property of biochar, synthesized from a green seaweed (Ulva lactuca), to remediate complex Remazol dye bearing wastewater was investigated. Preliminary trials were targeted to explore the remediation capacity of biochar towards each of Remazol dyes (Remazol brilliant blue R (RBBR), Remazol brilliant orange 3R (RBO3R), Remazol brilliant violet 5R (RBV5R), and Remazol Black B (RBB)) in single-solute system. The results show that equilibrium pH played a vital part with maximum sorption observed at pH 2.0. The isotherm experiments confirmed that biochar exhibited high uptakes of 0.301, 0.292, 0.265, and 0.224?mmol/g for RBO3R, RBBR, RBV5R, and RBB, respectively. Due to the presence of multiple dyes as well as high concentration of auxiliary chemicals, the performance of biochar to remediate Remazol effluent was inhibited markedly compared to single solute systems. Nevertheless, the dye removal efficiency was above 77.5% and the decolorization rate was high with more than 95% of total dye decolorization completed within 240?min. Our results provide novel insights into the potential of biochar to remove Remazol dyes from complex dye wastewaters.