DISTRIBUTION OF CARBON AMONG PHOTOSYNTHETIC END-PRODUCTS IN PHYTOPLANKTON OF THE EASTERN CANADIAN ARCTIC1

The distribution of ¹⁴C among photosynthetic end-products was examined in eastern Canadian arctic phytoplankton, with particular emphasis on the synthesis of lipids. The pattern of ¹⁴C distribution for phytoplankton at each of three depths was generally similar among populations from 12 stations. About 18% of the total ¹⁴C fixed was incorporated into lipids. At one station, phytoplankton were experimentally subjected to temperature and light conditions different from those in situ: lipid-¹⁴C did not exceed 30% of total ¹⁴C fixed within the temperature range -1.0 to 6.0° C and irradiance range 1 to 700 W · m^?2. It is suggested that low temperatures and low light intensities, even when, maintained for prolonged periods, are not fully sufficient conditions for eliciting high relative rates of ¹⁴C incorporation into lipids. It is possible that differences in species composition may be a factor accounting for different patterns of ¹⁴C distribution between north and south polar phytoplankton under apparently similar environmental conditions.     

Biosorption of metal ions byAzotobacter vinelandii

Azotobacter vinelandii was better than eitherDerxia gummosa orRhizobium trifolii for sorption of UO ₂ ²⁺ . Its maximum binding capacity was 0.25 mmol UO ₂ ²⁺ /g dry biomass with an affinity constant of 333 l/mmol at pH 4.1 according to the Langmuir model. In a semisynthetic medium,A. vinelandii showed the highest sorption capacity in the early stationary phase. The binding of UO ₂ ²⁺ , Cu²⁺, Ca²⁺ and Zn²⁺ was affected by the pH of the solution. With HCl as eluent, virtually all the sorbed UO ₂ ²⁺ was released. The presence of Cu²⁺, Cd²⁺, Ca²⁺, and Zn²⁺ inhibited the UO ₂ ²⁺ biosorption whereas Mg²⁺ and K⁺ had no effect.     

Relationship between capsular types 5 and 8 and phage types in Staphylococcus aureus isolates from cow, goat and ewe milk

Abstract In order to check the relationship between capsular polysaccharide (CP) type 5 and 8 and certain phage patterns, previously described in human Staphylococcus aureus clinical isolates, we typed 100 CP types 5 and 8 S. aureus strains isolated from cow, goat and ewe milk, with the human set of phages. The proportion of typable strains was much less than that found with human strains. The association between CP types 5 and 8 and phage patterns reported for human isolates was only partially confirmed and an original correlation between susceptibility to group III phages and CP type 5 was found.     

Chiral Recognition of N‐Phthaloyl,N‐Tetrachlorophthaloyl,and N‐Naphthaloyl α‐Amino Acids and Their Esters on Polysaccharide‐Derived Chiral Stationary Phases

Enantiomeric separations of N‐phthaloyl (N‐PHT), N‐tetrachlorophthaloyl (N‐TCPHT), and N‐naphthaloyl (N‐NPHT) α‐amino acids and their esters were examined on several kinds of polysaccharide‐derived chiral stationary phases (CSPs). Resolution capability of CSPs was greater Chiralcel OF than the others for N‐PHT and N‐NPHT α‐amino acids and their esters. In N‐TCPHT α‐amino acids and their esters, good enantioselectivities showed Chiralcel OG for N‐TCPHT α‐amino acids, Chiralpak AD for N‐TCPHT α‐amino acid methyl esters, and Chiralcel OD for N‐TCPHT α‐amino acid ethyl esters, respectively. From the results of liquid chromatography and computational chemistry, it is concluded that l ‐form is preferred and more retained with electrostatic interaction in case of interaction between N‐PHT α‐amino acid derivatives and Chiralcel OF, N‐TCPHT α‐amino acid derivatives and Chiralcel OD, and N‐NPHT α‐amino acid derivatives and Chiracel OF. On the other hand, d ‐form is preferred and more retained with van der Waals interaction in case of interaction between N‐TCPHT α‐amino acid ester derivatives and Chiralcel OG and Chiralpak AD. Chirality 24:1037–1046, 2012. © 2012 Wiley Periodicals, Inc.     

多糖的甲基化方法及图谱解析

本文对微量多糖的甲基化方法进行了研究。0.1 mg多糖样品用0.3 mL二甲亚砜溶解后,加入10 mg氢氧化钠粉末,室温下超声20 min。冰浴冷却后加入0.1 mL碘甲烷1,8～20℃下超声20 min,再加入0.1 mL碘甲烷,超声20 min。加入1 mL含4 mmol/L Na2S2O3的水,终止甲基化反应。反应液用0.5 mL氯仿提取4次,氯仿提取液用0.5 mL水处理5次。氯仿相用无水硫酸钠脱水后,氮气吹干。该法简便易行,甲基化程度高,适用于易溶(或难溶)于水和二甲亚砜的多糖。此外,本文对部分甲基化的糖醇乙酰酯衍生物的质谱图解析进行了阐述,并对特殊糖类样品的甲基化方法进行了说明。     

白术多糖WAM-1结构的色谱分析和原子力显微镜观察

通过热水浸提法从草本植物白术根茎提取的水溶性粗多糖,经DEAE-52纤维素柱层析分离和Sephadex G-200凝胶过滤柱层析纯化,得到组分WAM-1.采用高效液相色谱(HPLC)检测WAM-1的纯度,气相色谱(GC)对其单糖组分进行分析,原子力显微镜(AFM)对其分子外貌进行观测.结果显示:WAM-1为均一多糖,由葡萄糖和半乳糖以3.01:1摩尔比构成;在不同浓度溶液条件下,WAM-1分子以不同形态存在,多糖溶液的浓度对WAM-1的分子链构象及链间相互作用形式产生影响,推测可能与WAM-1分子内、分子间的氢键缔合作用有关.多糖浓度为10μg/mL时,可清晰的观察到WAM-1是以刚性链状形态存在,且具有多分支结构.     

β-蜕皮激素对蛹虫草液体培养菌丝体生长及代谢产物的促进作用

The effects of β-ecdysone on mycelial dry weight (MDW) and the yield of extracellular polysaccharide (EPS), intracellular polysaccharide (IPS) and cordycepin of Codyceps militaris in submerged cultivation was investigated. Adding 12mg/L of β-ecdysone to the culture medium, the MDW, the secretion volume of EPS per unit of MDW and total yield of EPS were increased by 18.5%, 181.7% and 63.2%, respectively. The yield of IPS was enhanced by 29.2%, when 1.2mg/L of β-ecdysone was added. When 4mg/L of β-ecdysone was provided, the amount of cordycepin per unit of MDW and the total yield of cordycepin were increased by 65.4% and 84.7%, respectively. These results demonstrated that β-ecdysone promoted the yield of MDW, EPS, IPS and cordycepin of Codyceps militaris mycelia, though this effect varied among different components. Significantly, β-ecdysone showed a more positive role in secondary metabolite (cordycepin) accumulation than in primary metabolite (IPS) production and growth of mycelia. Furthermore, β-ecdysone stimulated the secretion of EPS.     

CHANGES IN THE MORPHOLOGY AND POLYSACCHARIDE CONTENT OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) DURING FLAGELLATE GRAZING1

To investigate the changes in the morphology and polysaccharide content of Microcystis aeruginosa (Kütz.) Kütz. during flagellate grazing, cultures of M. aeruginosa were exposed to grazing Ochromonas sp. for a period of 9 d under controlled laboratory conditions. M. aeruginosa responded actively to flagellate grazing and formed colonies, most of which were made up of several or dozens of cells, suggesting that flagellate grazing may be one of the biotic factors responsible for colony formation in M. aeruginosa. When colonies were formed, the cell surface ultrastructure changed, and the polysaccharide layer on the surface of the cell wall became thicker. This change indicated that synthesis and secretion of extracellular polysaccharide (EPS) of M. aeruginosa cells increased under flagellate grazing pressure. The contents of soluble extracellular polysaccharide (sEPS), bound extracellular polysaccharide (bEPS), and total polysaccharide (TPS) in colonial cells of M. aeruginosa increased significantly compared with those in single cells. This finding suggested that the increased amount of EPS on the cell surface may play a role in keeping M. aeruginosa cells together to form colonies.     

3-methoxy aroylhydrazones – free radicals scavenging,anticancer and cytoprotective potency

Objective: This study aimed to determine the capability of newly designed 3-methoxy derivatives of salicylaldehyde benzoylhydrazone to influence the oxidative stress processes and to test their in vitro cytotoxicity.

Methods: We have used chemiluminescent and spectrophotometric model systems containing different types of reactive oxygen species (OH^●, OCl^─ and O₂^─●). The hydrazones effect on the viability of Hep-G2, HEK-293 and SH-SY5Y cell lines was determined via MTT assay.

Results: The comparative analysis of the C₅₀ values of the chemiluminescent investigation demonstrated moderate activity against the hydroxyl radicals (C₅₀?>?50?μmol/L) and remarkable reactivity in the systems containing a superoxide radical and a hypochlorous anion (C₅₀?● generation and consequent 2′-deoxyribose oxidative damage excluded the possibility of quenching effect and proved the direct interaction of the studied compounds with that generated in the system reactive oxygen species (ROS). The encapsulation of the studied derivatives into chitosan-alginate particles led to the protection and stabilization of their antioxidant activity as revealed by a one-month study using the ABTS ^●+ method. The cytotoxic study revealed less pronounced effects against the non-malignant cell line (HEK-293) compared to Hep-G2 and SH-SY-5Y cells.

Discussion: The incorporation of a hydroxyl group in the hydrazide part of a parent molecule which relates to better antioxidant effect in most of the studied systems is associated with higher IC₅₀ values in all cytotoxicity experiments and relates to the cytoprotective effect against N-methyl-D-aspartate-induced excitotoxicity in SH-SY5Y human neuronal cells.