Biosorption of Cr, Cu and Al bySargassum biomass

The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algaeSargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum uptake of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only 5 to 10% of Cr sorbed was eluted at pH 1.1. The stoichometric ion exchange between Cu and Ca ion was observed on Cu biosorption with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)₂ ⁺ or Cr(OH)²⁺. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of rawS. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl/HCl solution at pH3.     

PARTICULATE ORGANIC MATTER AS AN ALTERNATIVE NUTRIENT SOURCE FOR TROPICAL SARGASSUM SPECIES (FUCALES, PHAEOPHYCEAE)

Large Fucales are abundant on coastal coral reefs of the Great Barrier Reef, but are often limited by the availability of inorganic nutrients. Particle loads in these reef waters are high, which is generally perceived as detrimental for aquatic plants due to a reduction of light. Here, I provide evidence that several abundant Sargassum species supplement their nutrient supply with nutrients derived from the layer of particulate matter (PM) deposited on their thalli. In experiments involving removal or addition of PM, growth rates of Sargassum spp. were up to 180% higher when particles were present on the thalli. Tissue nitrogen and phosphorus levels of thalli with a surface PM layer were 10%–30% higher than those of thalli without PM. The amount of PM deposited in situ on thalli of five species of brown algae ranged from 0.6 to 0.9 g C_org·g⁻¹ dry weight alga, depending on the species' morphology. I suggest that a nutrient-rich diffusive boundary layer is created on the thallus surface by an epiphytic microbial community that remineralizes the particulate nutrients. When algal growth is nutrient limited, the use of particle-derived nutrients as a source alternative to nutrients in the water column may outweigh any potential adverse effects of the thallus particle layer.     

Seasonal changes of fatty acid composition and thermotropic behavior of polar lipids from marine macrophytes

Major glyco- and phospholipids as well as betaine lipid 1,2-diacylglycero-O-4'-(N,N,N-tri-methyl)-homoserine (DGTS) were isolated from five species of marine macrophytes harvested in the Sea of Japan in summer and winter at seawater temperatures of 20-23 and 3 degrees C, respectively. GC and DSC analysis of lipids revealed a common increase of ratio between n-3 and n-6 polyunsaturated fatty acids (PUFAs) of polar lipids from summer to winter despite their chemotaxonomically different fatty acid (FA) composition. Especially, high level of different n-3 PUFAs was observed in galactolipids in winter. However, the rise in FA unsaturation did not result in the lowering of peak maximum temperature of phase transition of photosynthetic lipids (glycolipids and phosphatidylglycerol (PG)) in contrast to non-photosynthetic ones [phosphatidylcholine (PC) and phosphatidylethanolamine (PE)]. Different thermotropic behavior of these lipid groups was accompanied by higher content of n-6 PUFAs from the sum of n-6 and n-3 PUFAs in PC and PE compared with glycolipids and PG in both seasons. Seasonal changes of DSC transitions and FA composition of DGTS studied for the first time were similar to PC and PE. Thermograms of all polar lipids were characterized by complex profiles and located in a wide temperature range between -130 and 80 degrees C, while the most evident phase separation occurred in PGs in both seasons. Polarizing microscopy combined with DSC has shown that the liquid crystal - isotropic melt transitions of polar lipids from marine macrophytes began from 10 to 30 degrees C mostly, which can cause the thermal sensitivity of plants to superoptimal temperatures in their environment.     

Phylogenetic relationships within the genus Sargassum (Fucales, Phaeophyceae), inferred from ITS-2 nrDNA, with an emphasis on the taxonomic subdivision of the genus

Sequences from the ribosomal DNA internal transcribed spacer‐2 (ITS‐2) were compared among species of Sargassaceae including the genera Sargassum and Hizikia. Species of different subgenera and sections of Sargassum were used to assess the taxonomic relationships within the genus, especially the subdivisions of the subgenus Bactrophycus. Sequences were aligned in accordance with their common secondary structure. Phylogenetic trees were constructed using neighbor‐joining, maximum likelihood and maximum parsimony methods with three species of Turbinaria as outgroups. The resulting phylogenetic trees showed that the genus Sargassum is divided into three clades corresponding to the subgenera Phyllotrichia, Sargassum and Bactrophycus. This last subgenus is further divided into four distinct groups: a Spongocarpus clade, a Teretia clade, a Hizikia clade, and a Halochloa/ Repentia clade. The position of the section Phyllo‐cystae, excluded from the subgenus Bactrophycus and included within the subgenus Sargassum is once again confirmed by the present study. Current results strongly support the assignation of Hizikia fusiformis to the genus Sargassum. Based on morphological differences and a distinct position in the molecular trees, Hizikia should be recognized as a section in the subgenus Bactrophycus so that Hizikia (Okamura) Yoshida, stat. nov. is proposed. A remarkably low divergence of ITS‐2 sequences was observed for the species in the sections Repentia and Halochloa, suggesting very recent radiation of these species. The subgenus Sargassum is divided into three clades corresponding to the three known sections: Acanthocarpicae, Malacocarpicae and Zygocarpicae, previously recognized by the morphology of receptacles. The position of Sargassum duplicatum, S. carpophyllum, S.yendoi, S. piluliferum and S. patens within the subgenus Sargassum is discussed.     

Size-dependence of reproductive allocation of Sargassum thunbergii (Sargassaceae, Phaeophyta) in Bohai Bay, China

Reproductive allocation (the proportion of biomass allocated to reproductive tissue, RA) in Sargassum thunbergii was studied in Yantai, Shandong Peninsula, southern coast of Bohai Bay, China. Annual reproduction initiated in mid-June and peaked in mid-July (90 ± 8% fertile thalli and 75 ± 6% RA mean). Both RA and percentage of fertile thalli exhibited significant temporal variations during reproduction. Sterile thalli were only observed in small length hierarchies at peak reproduction and mean values of RA showed a significantly hierarchical variation, suggesting that the size of thalli played an important role in reproduction and RA were size-dependent. Numerous receptacles were produced along the lateral branches during the reproductive period. A distinct seasonal pattern was observed wherein the presence of lateral branches was followed by the onset of reproduction. RA was positively correlated with the number of lateral branches, as well as the total length of lateral branches. In addition, fertile thalli decayed quickly after peak reproduction. The probability of decay was evidently higher for fertile than for sterile thalli, because all surviving thalli were sterile and short during July–August. So, a trade-off between reproduction and survival may exist at individual levels in S. thunbergii.     

Meroditerpenoids from the southern Australian marine brown alga Sargassum fallax

Chemical investigation of the southern Australian marine brown alga Sargassum fallax resulted in the isolation of three meroditerpenoids fallahydroquinone, fallaquinone and fallachromenoic acid together with the previously reported compounds sargaquinone [isolated and identified in a mixture with sargaquinoic acid], sargahydroquinoic acid, sargaquinoic acid and sargachromenol. As a result of this study the complete 2D NMR characterisation for sargaquinoic acid and sargahydroquinoic acid can now be reported for the first time. All structures were elucidated by detailed spectrometric analysis. Sargaquinoic acid and sargahydroquinoic acid displayed moderate antitumour activity.     

Investigation of the antifouling constituents from the brown alga Sargassum muticum (Yendo) Fensholt

One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms. In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included, compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found fatty acid. Pure palmitic acid showed antibacterial activity at 44 μg mL⁻¹, and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC₅₀ = 45.5 μg mL⁻¹), and the germination of Ulva lactuca spores at 3 μg mL⁻¹. No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling paint.     

Seasonal variation of phlorotannin in sargassacean species from the coast of the Sea of Japan

Variations in phlorotannin concentrations among the developmental stages of brown algae have been reported; however, the phlorotannin concentration plasticity associated with fluctuations in environmental factors make it difficult to determine the essential ontogenetic variation. The phlorotannin concentrations in five perennial sargassacean species where newly sprouted branches appear in summer and become fertile the following spring were examined every month during a year; and correlation with the developmental or seasonal environmental factors was determined. Although the phlorotannin fluctuated greatly throughout the year, the fluctuation patterns were relatively similar among the five species: phlorotannin showed a peak during July and August; gradually decreased in the winter; and increased in April. Performing a multiple regression analysis, the phlorotannin concentration did not correlate with thallus size in all species; and phlorotannin amounts were significantly affected by ambient abiotic factors in some species. The phlorotannin contents in newly sprouted branches were always higher than those in the long main branches during all seasons. When the phlorotannin contents were determined monthly for S. fulvellum (Turner) C. Agardh where the thalli were cultured from embryos in outdoor tanks, the phlorotannin concentrations were 3–4% of the dry matter (DM) in the juveniles and decreased to less than 1% of the DM in thalli >7.5 cm in length. However, the phlorotannin in these cultured thalli suddenly increased to 5.3% DM after being transplanted to the inshore coast; and then the concentration gradually decreased. The data show higher phlorotannin concentrations in younger sargassacean algae thalli and fluctuation of the phlorotannin amounts with extrinsic environmental factors.     

铜藻中β-丙氨酸的分离及结构鉴定

非蛋白质氨基酸在抗癌、抗菌、抗结核、抗坏血病等方面有着重要的作用。本文主要对铜藻中的游离氨基酸进行检测分析和部分分离纯化及结构鉴定方面的研究,为更好的开发利用这些天然产物提供技术支持。采用离子交换树脂层析法分离铜藻粗提液中的游离氨基酸,收集3 mol/L的氨水洗脱液,用PITC-HPLC柱前衍生反相高效液相色谱法对其进行检测分析,结果显示粗提液中除含有多种组成蛋白质的氨基酸外还有3种未知组分,且含量较高的常见蛋白质氨基酸为丙氨酸、脯氨酸、缬氨酸。采用半制备高效液相色谱系统制备分离了其中一种未知组分的衍生物MWZ2,经真空冷冻干燥后为略黄固体粉末,结合核磁共振波谱、高分辨质谱、红外光谱数据,最终鉴定MWZ2去掉已知取代基团PITC后的成分为β-丙氨酸,分子式为C3H7NO2,分子量为89.09。     

羊栖菜多糖诱导lovo细胞凋亡及其机理探讨

本课题研究羊栖菜多糖(Sargassum Fusiforme Polysaccharides,SFPS)诱导人大肠癌lovo细胞凋亡及凋亡过程中Caspase-3的变化及其意义。MTT法检测SFPS对大肠癌细胞增殖的抑制率;通过电镜、琼脂糖凝胶电泳、流式细胞术鉴定细胞凋亡;应用Western blot法测定Caspase-3酶原的变化; RT-PCR检测Caspase-3 mRNA表达。结果显示:SFPS作用lovo细胞24,36,48和72h的IC_(50)分别为375,355,178和60mg/L,表明对lovo细胞具有显著生长抑制作用。在电镜下,可见明显的细胞凋亡特征:细胞膜表面微绒毛减少、染色质固缩、边集,凋亡小体形成。在琼脂糖凝胶电泳中,药物浓度为5-300mg/L作用24h后,显示有凋亡细胞特有的DNA梯状条带;而500mg/L处理后梯状条带模糊,开始出现“涂片状”,表明在高药物浓度的作用下,细胞有坏死。流式细胞仪测得细胞凋亡率有剂量的依赖性;DNA直方图出现亚G1峰,但细胞周期时相的分布无明显改变。SFPS处理lovo细胞后,发现Caspase-3酶原蛋白表达降低,Caspase-3的mRNA高表达,并具有剂量和时间的依赖性。实验结果提示,SFPS在体外能够诱导lovo细胞凋亡,这可能是SFPS抑制肿瘤增殖的机制之一,而Caspase-3的活化参与了SFPS诱导lovo细胞凋亡的调控。