Evidence for positive selection in phycoerythrin genes of red algae and cyanobacteria Prochlorococcus and Synechococcus

Because of the shortage of phycoerythrin (PE) gene sequences from rhodophytes, peBA encoding beta- and alpha-subunits of PE from three species of red algae (Ceramium boydenn, Halymenia sinensis, and Plocamium telfariae) were cloned and sequenced. Different selection forces have affected the evolution of PE lineages. 8.9 % of the codons were subject to positive selection within the PE lineages (excluding high-irradiance adapted Prochlorococcus). More than 40 % of the sites may be under positive selection, and nearly 20 % sites are weakly constraint sites in high-irradiance adapted Prochlorococcus. Sites most likely undergoing positive selection were found in the chromophore binding domains, suggesting that these sites have played important roles in environmental adaptation during PE diversification. Moreover, the heterogeneous distribution of positively selected sites along the PE gene was revealed from the comparison of low-irradiance adapted Prochlorococcus and marine Synechococcus, which firmly suggests that evolutionary patterns of PEs in these two lineages are significantly different.

Reinstauración y lectotipificación del endemismo mediterráneo Plocamium fenestratum Kützing (Plocamiales, Rhodophyta)

Grupo de investigación en Biología Costera (BioCost), Facultad de Ciencias, Universidad de A Coruña. A Coruña, Spain

Antioxidant capacity and lipophilic content of seaweeds collected from the Qingdao coastline

Lipophilic extracts from 16 species of seaweeds collected along the Qingdao coastline were screened and evaluated for their antioxidant activities (AA) using the beta-carotene-linoleate assay system. The diethyl ether soluble extracts of all selected seaweeds exhibited various degrees of antioxidative efficacy in each screen. The highest antioxidant capacities among the tested samples were observed for Rhodomela confervoides and Symphyocladia latiuscula and were comparable with that of the well-known antioxidant butylated hydroxytoluene and greater than that of propyl gallate. The lipophilic content of all 16 samples and the chemical composition of 4 selected seaweeds, R. confervoides and S. latiuscula, which had higher AA, Laminaria japonica, which had intermediate AA, and Plocamium telfairiae, which had lower AA, were analyzed by gas chromatography and gas chromatography-mass spectrometry, respectively. Fatty acids and alkanes were found. The present data indicated an increase in antioxidative property with increasing content of unsaturated fatty acid. The result of this study suggests that seaweeds can be considered as a potential source for the extraction of lipophilic antioxidants, which might be used as dietary supplements or in production in the food industry. This is the first report on the antioxidant activities of lipophilic extracts from seaweeds.

Contribution of the UV component of natural sunlight to photoinhibition of photosynthesis in six species of subtidal brown and red seaweeds.

Field-collected specimens of three species of Laminaria and three species of subtidal red algae (Delesseria sanguinea, Plocamium cartilagineum and Phyllophora pseudoceranoides) were exposed to natural summer sunlight on Helgoland (southern North Sea) for up to 4 h at 15 °C. Dark-adapted variable fluorescence (Fv : Fm) was measured immediately after these treatments, and following 6, 24 and 48 h of recovery in moderate irradiances of white light. The response of plants to the full spectrum of natural sunlight was compared with that to PAR alone, UV-A + visible, UV-A + UV-B, or UV-A alone. The Fv : Fm values of all species were reduced to minimal values after 4 h in all of these treatments, but those of the more resistant species (Laminaria spp. and P. pseudoceranoides) were higher after shorter exposures to UV radiation alone than to PAR with or without UV. The recovery of Fv : Fm in all species was also more rapid in the two treatments that contained UV radiation alone than in those that included PAR. These results suggest that it is the high irradiances of PAR in natural sunlight which are responsible for the photoinhibition of photosynthesis of subtidal seaweeds and that the current ambient irradiances of UV radiation (either UV-B or UV-A) in northern temperate latitudes would not contribute significantly to this photoinhibition.

Biochemical composition of two red seaweed species grown on the Brazilian coast

BACKGROUND: Algae species have been used as an important source of food because they are highly nutritive considering their vitamin, protein, mineral, fiber, essential fatty acid and carbohydrate contents. However, a large number of seaweeds have been poorly studied, especially Brazilian species. Two red macroalgae species from the Brazilian coast (Plocamium brasiliense and Ochtodes secundiramea) were assessed with respect to their total lipid, fatty acid, total nitrogen, protein, amino acid and total carbohydrate contents. RESULTS: The total lipid contents (dry weight) were 36.3 and 35.4 g kg(-1); fatty acid contents were 9.3 and 12.1 g kg(-1); total nitrogen contents were 37.4 and 24.9 g kg(-1); protein contents were 157.2 and 101.0 g kg(-1); amino acid contents were 127.5 and 91.4 g kg(-1); and total carbohydrate contents were 520.3 and 450.7 g kg(-1) for P. brasiliense and O. secundiramea, respectively. CONCLUSION: Considering these compositions, both algae species were determined to have sources of protein, essential amino acids and carbohydrates similar to the edible seaweeds Laminaria japonica and Palmaria palmata. (C) 2011 Society of Chemical Industry

(Table 1) Presence of sublittoral macroalgae in the investigated profiles in Potter Cove, King George Island, Antarctica

The vegetation of a small fjord and its adjacent open shore was documented by subaquatic video. The distribution of individual species of macroalgae and the composition of assemblages were compared with gradients of light availability, hydrography, slope inclination, substratum, and exposition to turbulence and ice. The sublittoral fringe is usually abraded by winterly ice floes and devoid of large, perennial algae. Below this zone, the upper sublittoral is dominated by Desmarestia menziesii on steep rock faces, where water movements become irregular, or by Ascoseira mirabilis and Palmaria decipiens on weakly inclined slopes with steady rolling water movements. In the central sublittoral above 15 m, where turbulence is still active, Desmarestia anceps is outcompeting all other species on solid substratum, However, the species is not able to persist on loose material under these conditions. Instead, Himantothallus grandifolius may occur. Deeper, where turbulence usually is negligible, Desmarestia anceps also covers loose material. The change of dominance to Himantothallus grandifolius in the deep sublittoral cannot completely be explained at present. Himantothallus grandifolius also prevails in a mixed assemblage under the influence of grounding icebergs. Most of the smaller algae are opportunists with different degrees of tolerance for turbulence, but some apparently need more stable microhabitats and thus are dependent from continuing suppression of competitive large phaeophytes.

Thermo-chemical behaviour and chemical product formation from Polar seaweeds during intermediate pyrolysis

Fundamental analytical pyrolysis studies of biomass from Polar seaweeds, which exhibit a different biomass composition than terrestrial and micro-algae biomass were performed via thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass-spectrometry (Py-GC/MS). The main reason for this study is the adaptation of these species to very harsh environments making them an interesting source for thermo-chemical processing for bioenergy generation and production of biochemicals via intermediate pyrolysis. Several macroalgal species from the Arctic region Kongsfjorden, Spitsbergen/Norway (Prasiola crispa, Monostroma arcticum, Polysiphonia arctica, Devaleraea ramentacea, Odonthalia dentata, Phycodrys rubens, Sphacelaria plumosa) and from the Antarctic peninsula, Potter Cove King George Island (Gigartina skottsbergii, Plocamium cartilagineum, Myriogramme manginii, Hymencladiopsis crustigena, Kallymenia antarctica) were investigated under intermediate pyrolysis conditions. TGA of the Polar seaweeds revealed three stages of degradation representing dehydration, devolatilization and decomposition of carbonaceous solids. The maximum degradation temperatures Prasiola crispa were observed within the range of 220-320 C and are lower than typically obtained by terrestrial biomass, due to divergent polysaccharide compositions. Biochar residues accounted for 33-46% and ash contents of 27-45% were obtained. Identification of volatile products by Py-GC/MS revealed a complexity of generated chemical compounds and significant differences between the species. A widespread occurrence of aromatics (toluene, styrene, phenol and 4-methylphenol), acids (acetic acid, benzoic acid alkyl ester derivatives, 2-propenoic acid esters and octadecanoic acid octyl esters) in pyrolysates was detected. Ubiquitous furan-derived products included furfural and 5-methyl-2-furaldehyde. As a pyran-derived compound maltol was obtained by one red algal species (P. rubens) and the monosaccharide d-allose was detected in pyrolysates in one green algal (P. crispa). Further unique chemicals detected were dianhydromannitol from brown algae and isosorbide from green algae biomass. In contrast, the anhydrosugar levoglucosan and the triterpene squalene was detected in a large number of pyrolysates analysed. © 2013 Elsevier B.V. All rights reserved.