Selenylation Modification of Degraded Polysaccharide from Enteromorpha prolifera and Its Biological Activities

Polysaccharide extracted from Enteromorpha prolifera possessed excellent biological activities,but its molecular weight was greatly high which influenced the activity.Organic Se had higher biological activities and was safer than inorganic Se species.In the present study,Enteromorpha polysaccharide was degraded to low molecular weight by free-radical degradation method of H_2O_2 and ascorbic acid.By single factor and orthogonal experiments,the optimal degradation conditions were reaction time of 2 h,reaction temperature of 50℃,H_2O_2/ascorbic acid(n/n=1:1)concentration of 15 mmol L~(-1),and solid-liquid ratio of 1:50(g mL~(-1)).Then,the degraded polysaccharide was chemically modified to obtain its selenide derivatives by nitric acid-sodium selenite method.The selenium content was 1137.29μg g~(-1),while the content of sulfate radical had no change.IR spectra indicated that the selenite ester group was formed.Degraded polysaccharide selenide was characterized and evaluated for antioxidant,antifungal and antibacterial activities.The results showed that degraded polysaccharide selenide had strong capacity of scavenging DPPH and·OH free radical.It had significant antibacterial properties for Escherichia coli,Bacillus subtilis and Salmonella spp.,and it also had significant antifungal properties for Apple anthrax.The result ascertained degradation and selenylation modification did not change the main structure of polysaccharides.It was possible that free-radical degradation was an effective way for enhancing antioxidant activity to decrease molecular weight of polysaccharides.     

Molecular weight controllable degradation of <Emphasis Type="Italic">Laminaria japonica</Emphasis> polysaccharides and its antioxidant properties

In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides（LPS） was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C） were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight（Y） of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C）, was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A² + 2490.79B²+873.04C². The equation regression coefficient value（R² = 0.969） indicated that this equation was valid. The value of the adjusted determination coefficient（adjusted R² = 0.914） also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^-1 and IC50 of Mw 18.576 KDa was 1.02 mg mL^-1, which was fourfold higher than initial polysaccharide.     

In-vitro anticoagulant activity of fucoidan derivatives from brown seaweed Laminaria japonica

Fucoidan, a group of sulfated heteropolysaccharides, was extracted from Laminaria japonica, an important economic alga species in China. The anticoagulant activity of fucoidan and its derivatives (including sulfated, phosphorylated, and aminated fucoidan) was examined using in-vitro anticoagulant systems. The correlation between chemical variations within the fucoidan group and anticoagulant activity was determined. The in-vitro anticoagulant properties of fucoidan and its derivatives were determined by measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). The results indicate anticoagulant activity in all samples using APTT and TT assays; however, only the fucoidan derivatives affected the PT assay. Thus, the fucoidan derivatives were able to inhibit both intrinsic and extrinsic blood coagulants. Fucoidan (FPS) and its derivatives presented better anticoagulant activity than low molecular weight fucoidan (DFPS) and its derivatives, suggesting that molecular weight and proper conformation are contributing factors for anticoagulant activity of polysaccharides. Amino groups have a positive charge and can thus change the charge density of fucoidan. Accordingly, among the tested samples, aminated fucoidan (NF) was the most active reflecting the importance of charge density for anticoagulant activity. Available data obtained using in-vitro models suggest that the sulfate content, sulfate/total-sugar ratio, molecular weight, and the substituted group of fucoidan are important factors for anticoagulant activity but that the influence of sulfate, phosphate and amino groups on anticoagulant activity was different.     

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.     

Two-dimensional electrophoresis analysis of proteins extracted from <Emphasis Type="Italic">Alexandrium</Emphasis> sp. LC3

Two-dimensional electrophoresis(2-DE) of protein extracted and purified from Alexandrium sp. LC3 was conducted. In the SDS-PAGE study, the relative molecular weights of the proteins were mainly in the range of 14 kDa?31 kDa and 43 kDa?66 kDa, and more proteins were detected between 14 kDa and 31 kDa. With the improved protein preparation, the two-dimensional electrophoresis patterns indicated that the relative molecular weights of the proteins were between 14 kDa and 100 kDa, and most of them ranged from 14 kDa to 31 kDa. This was consistent with the result of the SDS-PAGE analysis. The isoelectric points were found to lie between 3.0 and 8.0, and most of them were in the range of 3.0?6.0. Better separation effect was acquired with pre-prepared immobilized gradient (IPG) strip (pH 3?5.6), and about 320 protein spots could be visualized on the 2-DE map by staining. Within pH 3?10 and pH 3?5.6 strips, the protein samples of Alexandrium sp. LC3 could be separated well.     

Purification and characterization of iron-cofactored superoxide dismutase from Enteromorpha linza

A superoxide dismutase was purified from Enteromorpha linza using a simple and safe procedure, which comprised phosphate buffer extraction, ammonium sulphate precipitation, ion exchange chromatography on Q-sepharose column, and gel filtration chromatography on Superdex 200 10/300GL. The E. linza superoxide dismutase （E/SOD） was purified 103.6-fold, and a yield of 19.1% and a specific activity of 1 750 U/rag protein were obtained. The SDS-PAGE exhibited E/SOD a single band near 23 kDa and the gel filtration study showed E/SOD＇s molecular weight is near 46 kDa in nondenatured condition, indicating it＇s a homodimeric protein. E/SOD is an iron-cofactored superoxide dismutase （Fe-SOD） because it was inhibited by hydrogen peroxide, insensitive to potassium cyanide. The optimal temperature for its maximal enzyme activity was 35℃, and it still had 29.8% relative activity at 0℃, then E/SOD can be classified as a cold-adapted enzyme. E/SOD was stable when temperature was below 40℃ or the pH was within the range of 5 10. The first 11 N-terminal amino acids orE/SOD were ALELKAPPYEL, comparison of its N-terminal sequence with other Fe-SOD N-terminal sequences at the same position suggests it is possibly a chloroplastic Fe-SOD.     

The hydrogen peroxide impact on larval settlement and metamorphosis of abalone <Emphasis Type="Italic">Haliotis diversicolor supertexta</Emphasis>

Abalone Haliotis diversicolor supertexta is an important economic mollusk. The settlement and metamorphosis are two critical stages during its development period, which has direct influence on abalone survival and production. The influence of reactive oxygen species （hydrogen peroxide） on abalone embryo and juvenile development were examined in this study. Larvae of Haliotis diversicolor supertexta were induced to settlement and metamorphose by exposure to seawater supplemented with hydrogen peroxide. They had the best performance at 800 μmol/L. The concentration of 1 000 μmol/L or higher was toxic to the larvae, as the larvae could settle down only at benthic diatom plates without complete metamorphosis. In addition, H2O2 adding time was critical to the larval performance. 24h after two-day post-fertilization was proved to be the optimal adding time. In this paper, two action mechanisms of hydrogen peroxide are discussed： （1） hydrogen peroxide has direct toxicity to ciliated cells, thus cause apoptosis; （2） hydrogen peroxide, as a product from catecholamines＇ autoxidation process in vivo, can reverse this process to produce neuro-transmitters to induce abalone metamorphosis.     

The hydrogen peroxide impact on larval settlement and metamorphosis of abalone Haliotis diversicolor supertexta

Abalone Haliotis diversicolor supertexta is an important economic mollusk.The settlement and metamorphosis are two critical stages during its development period,which has direct influence on abalone survival and production.The influence of reactive oxygen species(hydrogen peroxide) on abalone embryo and juvenile development were examined in this study.Larvae of Haliotis diversicolor supertexta were induced to settlement and metamorphose by exposure to seawater supplemented with hydrogen peroxide.They had the best performance at 800 μmol/L.The concentration of 1 000 μmol/L or higher was toxic to the larvae,as the larvae could settle down only at benthic diatom plates without complete metamorphosis.In addition,H2O2 adding time was critical to the larval performance.24h after two-day post-fertilization was proved to be the optimal adding time.In this paper,two action mechanisms of hydrogen peroxide are discussed:(1) hydrogen peroxide has direct toxicity to ciliated cells,thus cause apoptosis;(2) hydrogen peroxide,as a product from catecholamines' autoxidation process in vivo,can reverse this process to produce neuro-transmitters to induce abalone metamorphosis.     

Effects of Body Weight and Water Temperature on Maximum Food Consumption of Juvenile Sebastodes fuscescens （Houttuyn）

Maximum rate of food consumption ( Cmax ) was determined for juvenile Sebastodes fuscescens (Houttuyn) at water temperature of 10, 15, 20 and 25℃. The relationships of Cmax to the body weight (W) at each temperature were described by a power equation: lnCmax = a b lnW. Covariance analysis revealed significant interaction of the temperature and body weight. The relationship of adjusted Cmax to water temperature (T) was described by a quadratic equation: Cmax = -0.369 0.456T - 0.0117T^2. The optimal feeding temperature calculated from this equation was 19.5 ℃. The coefficients of the multiple regression estimation relating Cmax to body weight (W) and water temperature (T) were given in the Table 2.     

Thermohaline structure inhomogeneity associated with polynia at the northern margin of Emery Ice-shelf

Based on the hydrographic data in austral summer during the 22nd Antarctic Expedition of China(2005/2006),some features can be found about the northern margin of Emery ice shelf as follows.The heat content in the surface layer(0-50 m) at the eastern end and the western end of the ice-shelf margin is much higher than that at the middle.The upper mixing-layer depth and the seasonal thermocline depth at the middle of the ice-shelf northern margin are much shallower than those at the both ends.However there is much less difference between the middle and the ends in the bottom layer.The remote sensing photos show that the inhomogeneity in the surface-layer water is closely related to the spatial distribution of the floes and polynia in the area.     

Phylogenetic analysis of cultivable bacteria isolated from Arctic sea-ice

Phylogenetic analysis based on 16S rDNA of 8 strains of cultivable bacteria isolated from Arctic sea-ice was studied.The results showed that strain BJ1 belonged to genus Planococcus,which was a genus of low mole percent G C gram-positive bacteria;strain BJ6 belonged to genus Burkholderia of β-proteobacteria and the rest 6 strain all belonged to γ-proteobacteria,of which strain BJ8 was a species of Pseudoalteromonas,strain BJ2-BJ5 and BJ7 were members of genus Psychrobacter.Phylogenetic analysis also indicated that bacteria of genus Psychrobacter of the isolates formed a relatively independent phylogenetic cluster in comparison with other bacteria belonged to genus Psychrobacter.     

Information for authors

正1 Aims and Scope Advances in Polar Science(APS)is an international,peer-reviewed journal jointly sponsored by the Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.APS is a comprchensive academic journal dedicated to presentation of multi-disciplinary achievements in Arctic and Antarctic expeditions and research.Its primary purpose is to publish achievements in fundamental research,applied     

Advances in Polar Science CONTENTS(Volume 25,2014)

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Guide to Authors： Journal of Mountain Science

<正>AIMS AND SCOPE(Editorial Policy)The Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the world,such as the Tibetan Plateau,the Himalayas,the Alps,the Andes,the Rockies and many other mountain ranges of our planet.     

Journal of Mountain Science(JMS)

<正>The Journal of Mountain Science(JMS),founded in2004,is an international English-language journal on mountain sciences.JMS is supervised by the Chinese Academy of Sciences(CAS),sponsored by the Chengdu Institute of Mountain Hazards and Environment,CAS,published by Science Press China,and distributed by Springer exclusively throughout the world(excluding Mainland China).The JMS is published bimonthly,fulltexted in SpringerLink and CNKI,indexed/abstracted by     

Relationship of Arctic sea ice and Northern Hemispheric 500 hPa Polar vortices

Using the NCEP/NCAR reanalysis monthly 500 hPa height data on a 2.5 latitude-longitude grid and 1°×1° sea ice data,the polar vortex area,intensity index and arctic sea ice area index are calculated respectively,and the meridional distribution,period variation and the abrupts in the long range trend are analyzed to study their relationship.The results show that the meridional distribution of sea ice and polar vortex h-ave distinctive difference,the relative positions of them are different in the eastern and western hemispheres,and exept they have periods of 4 months,quasi half year,quasi year,4-5 years and 10 years commonly,and each of them has its own respective variation as well.The sea ice area is decreasing apparently since 1980's,so is the polar vortex area,but their abrupt changge time are different totally.The area of sea ice and polar vortex has prominent positive correlation,but the relationship of sea ice intensity,polar vortex intensity,polar vortex area is complicated.     

Preliminary study on plasma membrane fluidity of Psychrophilic Yeast Rhodotorula sp.NJ298 in low temperature

The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature. Plasma membrane proteins, fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp. NJ298 were investigated at -3 ℃, 0 ℃ and 8 ℃. The results showed that plasma membrane protein content was greater at -3 ℃ than that at 8 ℃, and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis; GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids (C18∶ 1 and C18∶ 2) and shorter chain saturated fatty acid (C10∶ 0) increased along with the decrease of the culture temperature from 8 ℃ to -3 ℃; HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane, percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at -3 ℃. However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at -3 ℃, 0 ℃ and 8 ℃. Hence these changes in plasma membrane's characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.     

Author Index for Journal of Mountain Science Volume 11,2014,pp 1-1656

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