Pachydictyols B and C: New Diterpenes from Dictyota dichotoma Hudson

Two new diterpenoids, pachydictyol B (1a/1b) and C (2), were isolated from the dichloromethane extract of the marine brown alga, Dictyota dichotoma, collected from the Red Sea coast of Egypt, along with the known metabolites, pachydictyol A (3a), dictyol E (4), cis-africanan-1α-ol (5a), fucosterol (6), tetrahydrothiophen-1,1-dioxide and poly-β-hydroxybutyric acid. GC-MS analysis of the nonpolar fractions also indicated the presence of β-bourbonene and nonanal, along with three hydrocarbons and five fatty acids or their simple derivatives, respectively. GC-MS analysis of the unsaponifiable algal petroleum ether extract revealed the presence of a further eight compounds, among them 2,2,6,7-tetramethyl-10-oxatricyclo[4.3.0.1(1,7)]decan-5-one (7), N-(4-bromo-n-butyl)-piperidin-2-one (8) and tert-hexadecanethiol. Structures 1–6 were assigned by 1D and 2D NMR, mass spectra (EI, CI, HREI and HRESI) and by comparison with data from related structures. The crude algal extract was potently active against the breast carcinoma tumor cell line, MCF7 (IC₅₀ = 0.6 µg mL⁻¹); pachydictyol B (1a) and dictyol E (4) showed weak antimicrobial properties, and the other compounds were inactive. Pachydictyols B (1a) and C (2) demonstrated a weak and unselective cytotoxicity against twelve human tumor cell lines with a mean IC₅₀ of >30.0 µM.     

铜绿假单胞菌algL基因在毕赤酵母中的表达及其性质研究

 【目的】通过构建毕赤酵母工程菌株,以期获得重组海藻酸裂解酶,并对其性质加以研究。【方法】采用PCR的方法,以铜绿假单胞菌（Pseudomonas aeruginosa）基因组DNA 为模板,克隆出约1.0kb的海藻酸裂解酶基因algL的成熟蛋白编码序列,并将其插入巴斯德毕赤酵母（Pichia pastoris）表达载体pPIC9K中,获得重组质粒pPIC9K-algL。重组质粒线性化后用聚乙二醇（PEG）法导入毕赤酵母菌株GS115中表达。【结果】用甲醇诱导培养基进行摇瓶发酵,表达得到40 kD的目的蛋白,酶活力达540 U•ml-1左右。经测定,该重组酶的最适反应pH为8.5,最适反应温度为40℃,并且在20～45℃,pH 3.0～12.0具有较好的稳定性。50 mmol•L-1的Co2+和Ca2+对酶活力均有显著的促进作用,Zn2+、Cu2+和Fe2+在不同浓度下对酶活力均有不同程度的抑制作用。在重组酶的辅助作用下,抗生素的抑菌效果明显提高。【结论】用重组毕赤酵母可高效表达外源海藻酸裂解酶,为其今后在工农业中的应用奠定了基础。     

浓缩单胞藻在虾夷扇贝育苗中的应用效果

将超滤浓缩单胞藻分别以25％、50％、75％和100％的比例与鲜活饵料配合用于培育虾夷扇贝Patinopecten yessoensis幼虫,通过对虾夷扇贝苗种培育过程中幼体生长发育指标的观测和水质指标的分析,研究了浓缩单胞藻在贝类育苗中的应用效果。结果表明：100％浓缩藻组水质较稳定;培育前期,25％、50％的浓缩藻组对苗种无不利影响;中后期幼体的附着率、成活率均高于单独投喂鲜活饵料的对照组,表明在幼体的中后期可完全投喂浓缩单胞藻饵料。     

Purification and characterization of glycerolipid acyl-hydrolase from the red alga Gracilaria vermiculophylla

ABSTRACT:   A glycerolipid acyl-hydrolase was purified 19-fold with a yield of 11% from the prostaglandin-producing red alga Gracilaria vermiculophylla by ammonium sulfate precipitation, anion-exchange chromatoraphy and gel filtration chromatography. Sodium dodecylsulfate– polyacrylamide gel electrophoresis of the final preparation showed a single band corresponding to a molecular mass of 20 kDa, but Superdex 200 fast protein liquid chromatography exhibited a molecular mass of 40 kDa. Accordingly, it was suggested that the purified enzyme was a homodimer of a 20 kDa subunit. The optimal temperature and pH were 37°C and 7–8, respectively. The purified enzyme catalyzed hydrolysis of the acyl groups of both glycoglycerolipids and phospholipids, especially monogalactosyldiacylglycerol and phosphatidylcholine. These results suggest that the enzyme hydrolyze the membrane lipids of the alga to release various saturated and unsaturated fatty acids, including arachidonic acid as substrate for prostaglandin synthesis.     

Effects of a fungicide, an insecticide, and a biopesticide on Tolypothrix scytonemoides

Lower concentrations of Bavistin supported good growth of Tolypothrix scytonemoides with maximum protein and pigment contents. The rates of photosynthetic oxygen evolution declined in cells grown in the pesticide-amended medium but rates of respiratory oxygen consumption were enhanced in cells grown in lower concentrations of Monocrotophos and Nimbicidin. Activities of nitrogenase and glutamine synthetase were affected in all the pesticide treatments but nitrogenase activity was enhanced in the presence of Bavistin. Release of ammonia and carbohydrates was enhanced in cells grown in pesticide-amended medium except for cells grown in medium containing Bavistin where the release of carbohydrates was reduced. New polypeptides of ∼280, 152, and 25 kDa (in 250 ppm Bavistin), ∼58 and 28 kDa (in 0.3 and 0.2-0.4 ppm Monocrotophos, respectively) and ∼31, 28, and 26 kDa (in 0.5 and 1.0 ppm Nimbicidin) were detected in the treated cells.     

海藻组织培养研究进展

海藻是重要的海洋生物资源,与人类生活密切相关,其不仅为人类提供食品和药品,还是重要工业原料藻胶的主要来源[1-2]。藻胶,如琼脂、卡拉胶和藻酸盐等,作为海藻的增值产品具有广泛的工业用途,可以用作乳化剂、凝胶剂、稳定剂、增稠剂和悬浮剂等[3]。近年来,过度开采导致自然资源被大量消耗、     

光照对4种单胞藻生长速率、叶绿素含量及细胞周期的影响

在不同光照周期、光照强度和光谱下,测定了小球藻Chlorellasp.、湛江等鞭金藻Isochrysiszhanjiangensis、青岛大扁藻Platym onas helgolandica和绿色杜氏藻Dunaliella viridis的生长速率及叶绿素含量。结果表明:当光照强度为3 000 lx时,在光照周期为24L∶0D、18L∶6D、12L∶12D、6L∶18D和0L∶24D的5个梯度组中,光照周期为18L∶6D时,4种藻的生长速率均最大,分别为0.227、0.150、0.175、0.360个/d;当光照周期为12L∶12D时,在光照强度为10 000、5 000、3 000、1 000、500 lx的5个梯度组中,光照强度为5 000 lx时,4种藻的生长速率均最大,分别为0.225、0.188、0.174、0.261个/d;在红、绿、蓝、白光不同光谱的照射下,以白炽灯下4种藻的生长速率最大,分别为0.185、0.165、0.257、0.322个/d,且在蓝光培养下小球藻、等鞭金藻和扁藻叶绿素a的含量较高。测定了在4种光源培养下扁藻的细胞周期,结果以在红光下培养的扁藻G1期占的比例最低,白光下次之,而在绿、蓝光下培养的扁藻G1期所占比例比在红、白光下高出3.8%~5.9%。因此,培养上述4种藻类的适宜光源为白光或红光。     

Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?

Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds.     

Sulfated Galactofucan from the Brown Alga Saccharina latissima—Variability of Yield,Structural Composition and Bioactivity

The fucose-containing sulfated polysaccharides (SP) from brown algae exhibit a wide range of bioactivities and are, therefore, considered promising candidates for health-supporting and medicinal applications. A critical issue is their availability in high, reproducible quality. The aim of the present study was to fractionate and characterize the SP extracted from Saccharina latissima (S.l.-SP) harvested from two marine habitats, the Baltic Sea and North Atlantic Ocean, in May, June and September. The fractionation of crude S.l.-SP by anion exchange chromatography including analytical investigations revealed that S.l.-SP is composed of a homogeneous fraction of sulfated galactofucan (SGF) and a mixture of low-sulfated, uronic acid and protein containing heteropolysaccharides. Furthermore, the results indicated that S.l. growing at an intertidal zone with high salinity harvested at the end of the growing period delivered the highest yield of S.l.-SP with SGF as the main fraction (67%). Its SGF had the highest degree of sulfation (0.81), fucose content (86.1%) and fucose/galactose ratio (7.8) and was most active (e.g., elastase inhibition: IC₅₀ 0.21 μg/mL). Thus, S.l. from the North Atlantic harvested in autumn proved to be more appropriate for the isolation of S.l.-SP than S.l. from the Baltic Sea and S.l. harvested in spring, respectively. In conclusion, this study demonstrated that habitat and harvest time of brown algae should be considered as factors influencing the yield as well as the composition and thus also the bioactivity of their SP.     

Structural characterization and anti-HSV-1 and HSV-2 activity of glycolipids from the marine algae Osmundaria obtusiloba isolated from Southeastern Brazilian coast

Glycolipids were extracted from the red alga Osmundaria obtusiloba from Southeastern Brazilian coast. The acetone insoluble material was extracted with chloroform/methanol and the lipids, enriched in glycolipids, were fractionated on a silica gel column eluted with chloroform, acetone and then methanol. Three major orcinol-positive bands were found in the acetone and methanol fractions, being detected by thin layer chromatography. The structures of the corresponding glycolipids were elucidated by ESI-MS and (1)H/(13)C NMR analysis, on the basis of their tandem-MS behavior and HSQC, TOCSY fingerprints. For the first time, the structure of sulfoquinovosyldiacylglycerol from the red alga Osmundaria obtusiloba was characterized. This molecule exhibited potent antiviral activity against HSV-1 and HSV-2 with EC(50) values of 42 μg/mL to HSV-1 and 12 μg/mL to HSV-2, respectively. Two other glycolipids, mono- and digalactosyldiacylglycerol, were also found in the alga, being characterized by ESI-MS/MS. The structural elucidation of algae glycolipids is a first step for a better understanding of the relation between these structures and their biological activities.