Abiotic factors in colony formation: effects of nutrition and light on extracellular polysaccharide production and cell aggregates of Microcystis aeruginosa

Colony morphology is important for Microcystis to sustain a competitive advantage in eutrophic lakes. The mechanism of colony formation in Microcystis is currently unclear. Extracellular polysaccharide (EPS) has been reported to play an important role in cell aggregate formation of some phytoplankton. Microcystis aeruginosa was cultivated under varied abiotic conditions, including different nutrient, light, and temperature conditions, to investigate their effects on EPS production and morphological change. The results show that nutrient concentration and light intensity have great effects on EPS production in M. aeruginosa. There was a considerable increase in EPS production after M. aeruginosa was cultivated in adjusted culture conditions similar to those present in the field (28.9mg C/L, 1.98mg N/L, 0.65mg P/L, light intensity:100 μmol/(m2s)). These results indicate that abiotic factors might be one of the triggers for colony formation in Microcystis.     

The changes of three components in coelomic fluid of Urechis unicinctus exposed to different concentrations of sulfide

The changes in heme (associated with hemoglobin), hemoglobin and hematin in the coelomic fluid of marine worm,Urechis unicinctus, exposed to different concentrations of sulfide, were investigated using biochemical techniques. When exposed to different sulfide concentrations for up to 96 h, the relative amounts of the three components changed in a regular pattern suggesting that the coelomocytes play an important role in the worm's tolerance to sulfide. The possible roles of heme compounds in sulfide tolerance of this species are discussed on the basis of our experimental data. This research was supported by the NSFC-KOSEF scientific cooperation program and NSFC (No. 30271039)     

Production of polyhydroxybutyrate by the marine photosynthetic bacterium Rhodovulum sulfidophilum P5

The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate (PHB) production were studied in batch cultures of the marine photosynthetic bacterium Rhodovulum sulfidophilum P5 under aerobic-dark conditions. The results show that the accumulation of PHB in strain P5 is a growth-associated process. Strain P5 had maximum biomass and PHB accumulation at 2%-3% NaCl, suggesting that the bacterium can maintain growth and potentially produce PHB at natural seawater salinity. In the nitrogen source test, the maximum biomass accumulation (8.10±0.09 g/L) and PHB production (1.11±0.13 g/L and 14.62%±2.25% of the cell dry weight) were observed when peptone and ammonium chloride were used as the sole nitrogen source. NH 4 + -N was better for PHB production than other nitrogen sources. In the carbon source test, the maximum biomass concentration (7.65±0.05 g/L) was obtained with malic acid as the sole carbon source, whereas the maximum yield of PHB (5.03±0.18 g/L and 66.93%±1.69% of the cell dry weight) was obtained with sodium pyruvate as the sole carbon source. In the carbon to nitrogen ratios test, sodium pyruvate and ammonium chloride were selected as the carbon and nitrogen sources, respectively. The best carbon to nitrogen molar ratio for biomass accumulation (8.77±0.58 g/L) and PHB production (6.07±0.25 g/L and 69.25%±2.05% of the cell dry weight) was 25. The results provide valuable data on the production of PHB by R. sulfidophilum P5 and further studies are on-going for best cell growth and PHB yield.     

Acute toxicity and biodegradation of endosulfan by the polychaeta Perinereis aibuhitensis in an indoor culture

The polychaete Perinereis aibuhitensis, a key species in estuarine ecosystems, can improve the culture condition of sediment. Endosulfan is an organochlorine pesticide used globally to control insects and mites; however, it is a source of pollution in aquaculture as a result of runoff or accidental release. In this study, we evaluated the toxicity of endosulfan to polychaeta and its ability to improve polluted sediment. Specifically, the effects of a series of endosulfan concentrations (0, 1.25, 2.5, 5, 10, 15, and 20 mg/L) were investigated, and the results indicated that the 24-h median lethal concentration (24-h LC₅₀) was 55.57 mg/L, while the 48-h median lethal concentration (48-h LC₅₀) was 15.56 mg/L, and the safe concentration was about 1.556 mg/L. In a 30-d exposure experiment, the animal specimen could decompose endosulfan effectively while improving endosulfan-polluted aquatic sediment.     

Purification and some properties of Fe protein of nitrogenase from

The Fe protein ofAnabaena cylindrica was first separated and purified by chromatography through DEAE-cellulose columns then by gel electrophoresis. The specific activity was up to 142.46 nmol C₂H₄/mg protein · min. It was homogeneous as shown by 1) a single band in the gel electrophorogram; 2) absence of Mo and tryptophan; 3) content of about 3.4 atoms of Fe per mole protein. The molecular weight of the Fe protein ofA. cylindrica was about 61,000 daltons as estimated by SDS-gel electrophoresis and calculated from the amino acid composition. The residues of aspartate and glutamate were about 2.6 times that of arginine and lysine in the Fe protein. Crossing Fe protein ofA. cylindrica with Mo?Fe protein ofAzotobacter vinelandii gave positive result. The reciprocal crossing also showed activity.     

Toxicity of single-walled carbon nanotubes on green microalga Chromochloris zofingiensis

Nanoparticles,or particles in size of 1-100 nm,are extensively used in the world in different applications.For instance,single-walled carbon nanotubes(SWCNTs) are commonly used in consumer products,such as biosensors,drug and vaccine delivery transporters,and novel biomaterials.Although nanoparticles do not cause safety concerns to consumers who use nanoparticle-containing products,these small particles are potentially harmful for workers who produce them in factories or in cases of discharge to aquatic ecosystems.SWCNTs do not have a natural analogue,so the effects on health of their disposal remain largely unknown.In this study,we evaluated the effects of SWCNTs on a population of the green microalga Chromochloris zofingiensis and the profile and production of pigments and fatty acids.The alga was incubated with SWCNTs for 6 days in 0(control),40,80,160,or 320 mg/L concentrations.SWCNTs showed both positive and negative effects on the growth of C.zofingiensis,with a biomass enhancement at low levels(40-160 mg/L) but inhibition at high levels(320 mg/L).By contrast,a decreased accumulation of fatty acids and pigments of C.zofingiensis was observed over the range of the tested concentrations.These results indicate that the markers on the inhibitive toxicity of SWCNTs are increasingly sensitive in the following order:biomass and fatty acids < primary carotenoids < chlorophylls < secondary carotenoids.C.zofingiensis is a suitable microalga for evaluating the ecotoxicological hazards of SWCNTs,especially in terms of pigmentation response.     

Fine root distribution pattern of different aged Leucaena leucocephala trees in debris flow source area in Jiangjia Gully,China

Fine root is critical to restrain soil erosion and its distribution pattern is of great influence on the restraining effects. This study studied the fine root biomass(Br) distribution of different aged Leucaena leucocephala(5, 10, 15 years) in debris flow source area in Jiangjia Gully by digging downward to the bottom at different distances to stem in three directions on slope. The results showed the Br increased dramatically by 143% from 5 years to 10 years and then rose slowly by 38% from 10 years to 15 years. The Br of 5 years was significantly asymmetric between uphill and alonghill directions, but there was little difference among directions for other ages, and a concentration trend appeared to exist in downhill and alonghill directions. Moreover, fine root(D≤1 mm) was significantly heavier than that of fine root(1mmD≤2 mm), playing a leading role in the vertical distribution of the whole fine root, with a logarithmic or an exponential function. The results presented may shed light on fine root distribution pattern and evaluation of its effect on slope stability in debris flow source area.     

Species and distribution of inorganic selenium in the Bohai Sea

1 INTRODUCTION Selenium is a ubiquitous trace element that ex- ists in multiple chemical forms in seawater in dif- ferent oxidation states and organic metalloid com- pounds. Selenium is essential for the growth of various photosynthetic species in natural…     

Microanalysis and preliminary pharmacokinetic studies of a sulfated polysaccharide from <Emphasis Type="Italic">Laminaria japonica</Emphasis>

A rapid, sensitive and reproducible high performance liquid chromatography (HPLC) method with post-column fluorescence derivatization has been developed to determine the amount of low-molecular-weight sulfated polysaccharide (GFS) in vivo. The metabolism of GFS has been shown to fit a two component model following its administration by intravenous injection, and its pharmacokinetic parameters were determined to be as follows: half-time of distribution phase (t _1/2α)=11.24±2.93 min, half-time of elimination phase (t _1/2β)=98.20±25.78 min, maximum concentration (C _max)=110.53 μg/mL and peak time (T _max)=5 min. The pharmacokinetic behavior of GFS was also investigated following intragastric administration. However, the concentration of GFS found in serum was too low for detection, and GFS could only be detected for up to 2 h after intragastric administration (200 mg/kg body weight). Thus, the bioavailability of GFS was low following intragastric administration because of the metabolism of GFS. In conclusion, HPLC with postcolumn derivatization could be used for quantitative microanalysis and pharmacokinetic studies to determine the presence of polysaccharides in the serum following intravenous injection.     

南海北部渔场表层沉积物中的硫化物

为了给南海北部渔场的资源和环境保护提供基础数据,用碘量法测定了南海北部陆架区表层沉积物中硫化物含量.结果表明,全部28份样品中硫化物含量为3.3～42.2mg/kg(干重,下同),平均为12.1mg/kg,符合外海含量低的一般规律,明显低于沿岸海湾的含量,远低于日本渔业环境质量标准(200mg/kg)和安全下限值(400mg/kg).硫化物含量在测站间和不同区域间存在一定差异,南北方向呈近岸(13.1mg/kg)略高于离岸(12.1mg/kg)、离岸略高于远岸(11.1mg/kg)的梯度分布,但梯度差异不显著(p＞0.10);东西方向的分布特点是粤西海域(23.7mg/kg)＞海南岛以东(15.3mg/kg)＞台湾浅滩(9.4mg/kg)≈粤东海域(8.7mg/kg)≈珠江口外海域(8.6mg/kg).空间分布不太均匀主要是受沉积物类型的影响,与陆源硫化物输入的关系不大.     

Optimization of the microwave-assisted extraction of phlorotannins from Saccharina japonica Aresch and evaluation of the inhibitory effects of phlorotannin-containing extracts on HepG2 cancer cells

The use of a microwave-assisted extraction(MAE) method for the extraction of phlorotannins from Saccharina japonica Aresch(S.japonica) has been evaluated with particular emphasis on the influential parameters,including the ethanol concentration,solid/liquid ratio,extraction time,extraction temperature,and microwave power.The MAE procedure was optimized using single-factor design and orthogonal array design(OAD).The content of total phlorotannins in S.japonica was determined using a Folin-Ciocalteu(FC) assay.A maximum total phlorotannin content of 0.644 mg of phloroglucinol equivalent per gram of dry weight plant(mg PGE/g DW) was obtained using the optimized model,which included an ethanol concentration of 55%,solid/liquid ratio of 1:8,extraction time of 25 min,irradiation power of 400 W,and temperature of 60°C.Under similar conditions,the application of a conventional extraction method led to a lower phlorotannin yield of 0.585 mg PGE/g WD.These results demonstrated that the MAE approach provided better results for the extraction of phlorotannins from S.japonica and was a promising technique for the extraction of phenolic compounds from S.japonica and other materials.In addition,screening tests for the inhibitory activity showed that the phlorotannin-containing extracts significantly inhibited the growth of human hepatocellular carcinoma cells(HepG2) by inducing their apoptosis.The morphological changes that occurred during cell apoptosis were characterized using Hoechst33258 staining.     

Optimization of dilute acid hydrolysis of Enteromorpha

Acid hydrolysis is a simple and direct way to hydrolyze polysaccharides in biomass into fermentable sugars. To produce fermentable sugars effectively and economically for fuel ethanol, we have investigated the hydrolysis of Enteromorpha using acids that are typically used to hydrolyze biomass:H2SO4, HCl, H3PO4 and C4H4O4 (maleic acid). 5%(w/w) Enteromorpha biomass was treated for different times (30, 60, and 90 min) and with different acid concentrations (0.6, 1.0, 1.4, 1.8, and 2.2%, w/w) at 121°C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars (glucose and xylose) was high, (230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose), with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.     

Effect of dissolved oxygen on swimming ability and physiological response to swimming fatigue of whiteleg shrimp (Litopenaeus vannamei)

The swimming endurance of whiteleg shrimp(Litopenaeus vannamei, 87.66 mm ± 0.25 mm, 7.73 g ± 0.06 g) was examined at various concentrations of dissolved oxygen(DO, 1.9, 3.8, 6.8 and 13.6 mg L-1) in a swimming channel against one of the five flow velocities(v1, v2, v3, v4 and v5). Metabolite contents in the plasma, hepatopancreas and pleopods muscle of the shrimp were quantified before and after swimming fatigue. The results revealed that the swimming speed and DO concentration were significant factors that affected the swimming endurance of L. vannamei. The relationship between swimming endurance and swimming speed at various DO concentrations can be described by the power model(ν·tb = a). The relationship between DO concentration(mg L-1) and the swimming ability index(SA∫ 9000I), defined as SAI =vdt( cm), can be described as SAI = 27.947 DO0.137(R2 = 0.9312). The 0level of DO concentration directly affected the physiology of shrimp, and exposure to low concentrations of DO led to the increases in lactate and energetic substrate content in the shrimp. In responding to the low DO concentration at 1.9 mg L-1 and the swimming stress, L. vannamei exhibited a mix of aerobic and anaerobic metabolism to satisfy the energetic demand, mainly characterized by the utilization of total protein and glycogen and the production of lactate and glucose. Fatigue from swimming led to severe loss of plasma triglyceride at v1, v2, and v3 with 1.9 mg L-1 DO, and at v-11 with 3.8, 6.8 and 13.6 mg L DO, whereas the plasma glucose content increased significantly at v3, v4 and v5 with 3.8 and 6.8 mg L-1 DO, and at v5 with 13.6 mg L-1 DO. The plasma total protein and hepatopancreas glycogen were highly depleted in shrimp by swimming fatigue at various DO concentrations, whereas the plasma lactate accumulated at high levels after swimming fatigue at different velocities. These results were of particular value to understanding the locomotory ability of whiteleg shrimp and its physiological changes, further contributing to the improvement of capture and rearing technique.     

Antithrombotic effects of bromophenol, an alga-derived thrombin inhibitor

Thrombin, the ultimate proteinase of the coagulation cascade, is an attractive target for the treatment of a variety of cardiovascular diseases. A bromophenol derivative named (+)-3-(2,3-dibromo-4, 5-dihydroxy-phenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroiso-benzofuran 1, isolated from the brown alga Leathesia nana exhibited significant thrombin inhibitory activity. In this study, we investigated the inhibition of human thrombin in vitro with this bromophenol derivative, and its antithrombotic efficacy in vivo using the arteriovenous shunt model and the ferric chloride-induced arterial thrombosis model in rats. The results show that the bromophenol derivative is a potential inhibitor of thrombin (IC₅₀=1.03 nmol/L). In antithrombotic experiments in vivo, the bromophenol derivative also shows good effect comparing with the control group. These data indicate that the bromophenol derivative is a potential drug for prophylaxis and the treatment of thrombotic diseases.     

Lipid oxidation and fatty acid composition in salt-dried yellow croaker (<Emphasis Type="Italic">Pseudosciaena polyactis</Emphasis>) during processing

Lipid oxidation in salt-dried yellow croaker (Pseudosciaena polyactis) was evaluated during processing with commonly used analytical indices, such as the peroxide value (POV), the thiobarbituric acid reactive substances (TBARS) value, and oxidative-relative lipoxygenase (LOX) activity. Additionally, fatty acids were analyzed using gas chromatography-mass spectrometry. Both POV and TBARS increased significantly (P < 0.05) at the rinsing stage. POV reached its peak value of 3.63 meq O₂ per kg sample at the drying stage, whereas TBARS constantly increased from 0.05 to 0.20 mg MDA per kg sample. Processing of salt-dried yellow croaker had an extremely significant (P < 0.01) effect on LOX activity. Twenty-six fatty acids were identified. Combined eicosapentaenoic acid (EPA; C20:5n3) and docosahexaenoic acid (DHA; C22:6n3) content varied between (19.20 ± 0.37) mg g^?1 and (23.45 ± 1.05) mg g^?1. The polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratio in yellow croaker was 0.73–1.10, and the n-6/n-3 PUFA ratio was approximately 0.13–0.20. The contents of most fatty acids varied significantly (P < 0.05) during the different processing stages, and these differences were caused by lipid oxidation. C18:0, C16:1n7, C19:0, and C22:6n3 showed clear changes in principle component one of a principle components analysis. These fatty acids are potential markers for evaluating lipid oxidation in fish muscle because there was a significant correlation between these markers and TBARS and LOX activity (P < 0.05) with Pearson’s coefficients > 0.931.     

Extraction of astaxanthin from Euphausia pacific using subcritical 1, 1, 1, 2-tetrafluoroethane

Euphausia pacific is an important source of natural astaxanthin.Studies were carried out to assess the extractability of astaxanthin from E.pacific using subcritical 1,1,1,2-tetrafluoroethane(R134a).To examine the effects of multiple process variables on the extraction yield,astaxanthin was extracted under various conditions of pressure(30-150 bar),temperature(303-343 K),time(10-50 min),flow rate(2-10 g min-1),moisture content(5.5%-63.61%),and particle size(0.25-0.109 mm).The results showed that the extraction yield increased with temperature,pressure,time and flow rate,but decreased with moisture content and particle size.A maximum yield of 87.74% was obtained under conditions of 100 bar,333 K,and 30 min with a flow rate of 6 g min-1 and a moisture content of 5.5%.The substantial astaxanthin yield obtained under low-pressure conditions demonstrates that subcritical R134a is a good alternative to CO 2 for extraction of astaxanthin from E.pacific.     

Picoplankton distribution in different water masses of the East China Sea in autumn and winter

Picoplankton distribution was investigated in different water masses of the East China Sea in November,2006 and February,2007.The autumn and winter cruises crossed three major water masses:the coastal water mass(CWM),the mixed water mass(MWM),which forms on the continental shelf,and the Kuroshio water mass(KWM).Picoplankton composition was resolved into four main groups by flow cytometry,namely Synechococcus,Prochlorococcus,picoeukaryotes,and heterotrophic bacteria.The average abundances of Synechococcus,picoeukaryotes,and heterotrophic bacteria were(0.63±10.88)×103,(1.61±1.16)×103,(3.39±1.27)×105 cells/mL in autumn and(6.45±8.60)×103,(3.23±2.63)×103,(3.76±1.37)×105 cells/mL in winter,respectively.Prochlorococcus was not found in the CWM and seldom observed in surface samples in either season.However,Prochlorococcus was observed in the MWM and KWM(approximately 10 3 cells/mL) in both autumn and winter.Synechococcus distribution varied considerably among water masses,with the highest levels in KWM and lowest levels in CWM.The depth-averaged integrated abundance of Synechococcus was approximately 5-fold higher in KWM than in CWM,which may be due primarily to water temperature.In the MWM,Synechococcus was resolved as two subgroups;the presence of both subgroups was more common in autumn.Picoeukaryote abundance varied less among water masses than Synechococcus,and heterotrophic bacteria depth-averaged integrated abundance exhibited the smallest seasonal variations with respect to water mass.Correlation analysis showed that relationships between picoplankton abundances and environmental factors(temperature,nutrients,and chlorophyll a) differed among the three water masses,suggesting that the three water masses have different effects on picoplankton distribution(particularly Synechococcus).     

Strain and culture medium optimization for production enhancement of prodiginines from marine-derived Streptomyces sp. GQQ-10

A mutant (GQQ-M6) of a Sponge-Derived streptomyces sp. GQQ-10 obtained by UV-induced mutation was used for producing prodiginines (PGs). Single factor experiments and orthogonal array design (OAD) methods were employed for medium optimization. In the single factor method, the effects of soluble starch, glucose, soybean flour, yeast extract and sodium acetate on PGs production were investigated individually. In the subsequent OAD experiments, the concentrations of these 5 key nutritional components combined with salinity were further adjusted. The mutant strain GQQ-M6 gave a 2.2-fold higher PGs production than that of the parent strain; OAD experiments offered a PGs yield of 61mg L-1, which was 10 times higher than that of the initial GQQ-10 strain under the original cultivation mode.     

De-eutrophication of effluent wastewater from fish aquaculture by using marine green alga Ulva pertusa

The de-eutrophication abilities and characteristics of Ulva pertusa, a marine green alga, were investigated in Qingdao Yihai Hatchery Center from spring to summer in 2005 by analyzing the dynamic changes in NH ₄ ⁺ , NO ₃ ^? , NO ₂ ^? as well as the total dissolved inorganic nitrogen (DIN). The results show that the effluent wastewater produced by fish aquaculture had typical eutrophication levels with an average of 34.3 μmol L^?1 DIN. This level far exceeded the level IV quality of the national seawater standard and could easily lead to phytoplankton blooms in nature if discarded with no treatment. The de-eutrophication abilities of U. pertusa varied greatly and depended mainly on the original eutrophic level the U. pertusa material was derived from. U. pertusa used to living in low DIN conditions had poor DIN removal abilities, while materials cultured in DIN-enriched seawater showed strong de-eutrophication abilities. In other words, the de-eutrophication ability of U. pertusa was evidently induced by high DIN levels. The de-eutrophication capacity of U. pertusa seemed to also be light dependent, because it was weaker in darkness than under illumination. However, no further improvement in the de-eutrophication capacity of U. pertusa was observed once the light intensity exceeded 300 μmol M² S^?1. Results of semi-continuous wastewater replacement experiments showed that U. pertusa permanently absorbed nutrients from eutrophicated wastewater at a mean rate of 299 mg/kg fresh weight per day (126 mg/kg DIN during the night, 173 mg/kg in daytime). Based on the above results, engineered de-eutrophication of wastewater by using a U. pertusa filter system seems feasible. The algal quantity required to purify all the eutrophicated outflow wastewater from the Qingdao Yihai Hatchery Center into oligotrophic level I clean seawater was also estimated using the daily discharged wastewater, the average DIN concentration released and the de-eutrophication capacity of U. pertusa.