Influence of salinity and nitrogen content on production of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) by Skeletonema costatum

The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate(DMSP) and dimethylsulfide(DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum,an ecologically important species.Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield,but increased intracellular DMSP per cell by 30%.Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell.These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant.The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.     

Antioxidant system responses in two co-occurring green-tide algae under stress conditions

Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera(Müller) J. Agardh has been identified as the bloom-forming alga,co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U. prolifera exhibited a high abundance initially and then decreased dramatically,while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide(in-situ) and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera,but not in U. intestinalis. In U. prolifera,we observed a significant decrease in total antioxidant ability(T-AOC),antioxidant enzymes(SOD and Apx),and non-enzyme antioxidants(GSH and As A) in-situ. U. intestinalis showed the same pattern of T-AOC and SOD,but its Gpx,Apx,and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems.     

BIOCONCENTRATION OF TETRACHLOROBENZENE IN MARINE ALGAE

INTRODUCTIONChlrinatal~arewidelyedinindusnyandhouseholds,andsoisofsboi-ficantenviID~lcom,hauseitisoftenndaswaste.contributingtothepoilutantsinalltyPesofwater(Afghanetal.,l979).AlthoughsornedataontoxidtyandbioconnitionofchiorinatalboinaquaticorganismSwerepublishedopbasetal.,l987,LohnerCtal.,l987,Maunot,l987,Kuhnctal.,l99O),thebioCOntritionpotritinlparade,indudingk,,k,andBCF,werenotdetenninWelldriusethernehodsford~ngtheparaIneterswereleSsthanaccurate(Wangetal.,l996).Thepresentstudyab…     

Immunological cross-reactions between P700 chlorophyll-proteins isolated from two marine green algae and one higher plant

P₇₀₀ Chl-protein was isolated from a marine green algaBryopsis corticulans with SDS-resolved thylakoid membranes by SDS-PAGE. After elution from the gel, the recovered protein revealed a 100 KD polypeptide by re-electrophoresis. The same SDS-PAGE procedure was used to isolate P₇₀₀ Chl-proteins from spinach (Spinacea oleracea) and another marine green algaCodium fragile. Polyclonal antibodies toBryopsis P₇₀₀ protein were raised in rabbits. The antibodies were shown to cross-react with P₇₀₀ Chl-protein and Chl-protein complexes containing P₇₀₀ protein fromB. Corticulans, C. f ragile, and even spinach. Results indicate similarity of the amino acid sequences of the P₇₀₀ Chl-proteins and the highly conserved structure of the apoproteins of phylogenetically distant species over evolution. The antibodies cross-react with none of the components of PSII in the species tested, indicating an independent pathway of evolution of photosystem I and photosystem II of later origin. Contribution No. 1717 from the Institute of Oceanology, Academia Sinica     

SCREENING FOR ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES IN SOME MARINE ALGAE FROM THE FUJIAN COAST OF CHINA WITH THREE DIFFERENT SOLVENTS

Three different solvents viz ethanol, acetone and methanol-toluene (3:1) were used to extract antibiotics from 23 species of marine algae belonging to the Chlomphyta, Phaeophyta and Rhodophyta. Their crude extracts were tested for antibacterial and antifungal activities. Among them, the ethanol extract showed the strongest activity against the bacteria and fungi tested. Four species of the Rhodophyta (Laurenc/a okamurai, Dasya scoparia, Grateloupia filicina and plocamium telfairiae ) showed a wide spectrum of antibacterial activity. Every solvent extract from the four species was active against all the bacteria tested. The test bacterium Pseudomonas solancearum and the fungus Penicilium citrinum were most sensitive to the extracts of marine algae. In general, the extracts of seaweeds inhibited bacteria more strongly than fungi and species of the Rhodophyta showed the greatest activity against the bacteria and fungi tested.     

SCREENING OF AGGLUTININS IN MARINE ALGAE FROM FUJIAN COAST OF CHINA

Thirty-three species of marine algae belonging to Rhodophyta, Phaeophyta and Chlorophyta from the Fujian coast were examined for agglutinins with different animal and human erythrocytes. Protein extracts from 26 species were active against at least one type of the erythrocytes tested. There were 3 species (Grateloupia imbricata, lshigefoliacea and Entermorpha prolifera) whose extracts could agglutinate all the erythrocytes used. The lowest protein concentration required to produce erythrocyte agglutination varied remarkably, from 3.1μg/ml to 500μg/ml . The strongest activity was found in the agglutina-tion of rabbit erythrocytes by Gloiopeltis furcata extract. Inhibition assays performed with nine mono- and bisaccharides indicated that agglutinations of rabbit erythrocytes by extracts of 7 species were inhibited by one or more types of the sugars assayed. The agglutinating activity shown by extracts of most species wasnot affected when the test solution was heated to 90℃, but was lost at 95℃ - 100℃. A few extracts losttheir activity at 60 RS, 65 RS and 75 RS, respectively.     

海南省三亚海藻资源调查

通过对海南島三亚海藻的分布和种类进行深入调查,采集和整理了标本123号,计35属53种,并分析了三亚的气候和环境条件对海藻的生长与分布的关系,为三亚海藻的开发与利用提供了第一手资料。     

The isolation of prophyra-334 from marine algae and its UV-absorption behavior

1 INTRODUCTIONSolar ultraviolet radiation on the earth's surfaceincreases with the depletion of stratospheric ozone(Crutzen, 1992; Kerr and McElroy, 1993; Mad-ronich et al., 1998). Ultraviolet radiation is a highlyactive component of solar spectrum. The excessiveUV radiation has deleterious effects on all plant,animal and microbial groups exposed to solar radia-tion, including the destruction of DNA, proteins andother molecules (Harm, 1980), inhibition of photo-synthesis and growth (W…     

Effect of nitrogen to phosphorus ratios on cell proliferation in marine micro algae

The ratio of nitrogen/phosphorus (N/P) is known to affect cell proliferation of some marine micro algae. We evaluated the effect of N/P ratios on the proliferation and succession of phytoplankton using five marine micro algae species. We used two sources of nitrogen, NH₄Cl (N₁) and urea (N₂), and a single source of phosphorous, NaH₂PO₄(P). The optimal N/P ratio that differed among the five species was affected by the source of nitrogen, being as follows (N₁/P, N₂/P in order): Thalassiosira sp. (30/1, 20/1), Heterosigma akashiwo (30/1, 30/1), Chroomonas salina (20/1, 30/1), Chaetoceros gracilis (40/1, 60/1), and Alexandrium sp. (10/1, 30/1). Thus, the source of nitrogen must be considered when analyzing the N/P ratio. Our results provide insight for predicting phytoplankton succession in coastal waters and may be used to forecast the potential risk of harmful algal blooms.     

Effect of nitrogen to phosphorus ratios on cell proliferation in marine micro algae

The ratio of nitrogen/phosphorus (N/P) is known to affect cell proliferation of some marine micro algae. We evaluated the effect of N/P ratios on the proliferation and succession of phytoplankton using five marine micro algae species. We used two sources of nitrogen, NH4Cl (N1) and urea (N2), and a single source of phosphorous, NaH2PO4(P). The optimal N/P ratio that differed among the five species was affected by the source of nitrogen, being as follows (N1/P, N2/P in order): Thalassiosira sp. (30/1, 20/1),...     

Oxygen consumption and ammonia-N excretion of Meretrix meretrix in different temperature and salinity

Effects of temperatures and salinities on oxygen consumption and ammonia-N excretion rate of clam Meretrix meretrix were studied in laboratory from Oct. 2003 to Jan. 2004. Two schemes were designed in incremented temperature at 10, 15, 20, 25℃ at 31.5 salinity and in incremented salinity at16.0, 21.0, 26.0, 31.5, 36.0, and 41.0 at 20℃, all for 8-10 days. From 10 to 25℃, both respiration and excretion rate were increased. One-way ANOVA analysis demonstrated significant difference （P〈0.01） in physiological parameters in this temperature range except between 15 and 20℃. The highest Q10 thermal coefficient value （12.27） was acquired between 10 and 15℃, and about 1 between 15 and 20℃, indicating M. meretrix could well acclimate to temperature changes in this range. Salinity also had significant effects on respiration and excretion rate （P〈0.05）. The highest values of respiration and excretion rate of M. meretrix were recorded at 16.0 salinity （20℃）. These two physiological parameters decreased as salinity increased until reached the minimum Q10 value at 31.5 （20℃）, then again, these parameters increased with increasing salinity from 31.5 to 41.0. M. meretrix can catabolize body protein to cope with osmotic pressure stress when environmental salinity is away from its optimal range. No significant difference was observed between 26.0 and 36.0 in salinity （P〉0.05）, suggesting that a best metabolic salinity range for this species is between 26.0 and 36.0.     

Characterization and analysis of ribosomal proteins in two marine calanoid copepods

Copepods are among the most abundant and successful metazoans in the marine ecosystem. However, genomic resources related to fundamental cellular processes are still limited in this particular group of crustaceans. Ribosomal proteins are the building blocks of ribosomes, the primary site for protein synthesis. In this study, we characterized and analyzed the c DNAs of cytoplasmic ribosomal proteins(c RPs) of two calanoid copepods, P seudodiaptomus poplesia and A cartia pacifi ca. We obtained 79 c RP c DNAs from P. poplesia and 67 from A. pacifi ca by c DNA library construction/sequencing and rapid amplifi cation of c DNA ends. Analysis of the nucleic acid composition showed that the copepod c RP-encoding genes had higher GC content in the protein-coding regions(CDSs) than in the untranslated regions(UTRs), and single nucleotide repeats(3 repeats) were common, with "A" repeats being the most frequent, especially in the CDSs. The 3′-UTRs of the c RP genes were signifi cantly longer than the 5′-UTRs. Codon usage analysis showed that the third positions of the codons were dominated by C or G. The deduced amino acid sequences of the c RPs contained high proportions of positively charged residues and had high p I values. This is the fi rst report of a complete set of c RP-encoding genes from copepods. Our results shed light on the characteristics of c RPs in copepods, and provide fundamental data for further studies of protein synthesis in copepods. The copepod c RP information revealed in this study indicates that additional comparisons and analysis should be performed on different taxonomic categories such as orders and families.     

Domestication of marine microalga Nannochloropsis oceanica to freshwater medium and the physiological responses

Marine microalga Nannochloropsis oceanica LAMB0001 were domesticated(-73 0 generations,-two days each)to adapt freshwater BGll medium.A number of freshwater medium adapted colonyderived strains were obtained.The strains were verified phylogenetically to be N.oceanica LAMB0001 based on the 18 S ribosomal RNA gene.Freshwater-medium adapted strain(FA1)grew faster in the BG11 medium prepared with freshwater than wild-type N.oceanica grew in f/2 medium prepared with seawater.We assumed that(1)the expression patterns of the genes that expressed differentially between FA1 and the wild-type N.oceanica exposing to the BG11 medium(WT-F)have been reprogrammed;(2)the physiological processes in which these genes involved have been modified;and(3)a Gene Ontology(GO)term or a KEGG pathway enriched by DEGs between FA1 and WT-F has been up-or down-regulated if it was enriched simultaneously by up-or down-regulated DEGs between FA1 and WT-F,respectively.Under these assumptions,we found that FA1 reprogrammed the expression patterns of a set of genes that involved in cell adhesion,membrane and membrane integrity,material transportation,cell movement,and cellular signaling network.These changes in cellular functions and metabolic pathways indicate that the microalga modified its gene expression pattern in a wide function range and at a high regulation rank in order to adapt to the freshwater medium.It is feasible to domesticate marine microalgae to a freshwater habitat,which may aid to modify their cultivation performances.     

Oxygen consumption and ammonia-N excretion of Meretrix meretrix in different temperature and salinity

Effects of temperatures and salinities on oxygen consumption and ammonia-N excretion rate of clamMeretrix meretrix were studied in laboratory from Oct. 2003 to Jan. 2004. Two schemes were designed in incremented temperature at 10, 15, 20, 25°C at 31.5 salinity and in incremented salinity at 16.0, 21.0, 26.0, 31.5, 36.0, and 41.0 at 20°C, all for 8–10 days. From 10 to 25°C, both respiration and excretion rate were increased. One-way ANOVA analysis demonstrated significant difference (P<0.01) in physiological parameters in this temperature range except between 15 and 20°C. The highestQ ₁₀ thermal coefficient value (12.27) was acquired between 10 and 15°C, and about 1 between 15 and 20°C, indicatingM. meretrix could well acclimate to temperature changes in this range. Salinity also had significant effects on respiration and excretion rate (P<0.05). The highest values of respiration and excretion rate ofM. meretrix were recorded at 16.0 salinity (20°C). These two physiological parameters decreased as salinity increased until reached the minimumQ ₁₀ value at 31.5 (20°C), then again, these parameters increased with increasing salinity from 31.5 to 41.0.M. meretrix can catabolize body protein to cope with osmotic pressure stress when environmental salinity is away from its optimal range. No significant difference was observed between 26.0 and 36.0 in salinity (P>0.05), suggesting that a best metabolic salinity range for this species is between 26.0 and 36.0. This work is supported by National High-Tech R & D Program of China. (863 Program) (2002AA603014).     

Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions.During the 245-day incubation period,changes in the concentrations of TOC,major algal fatty acid components (14:0,16:0,16:1,18:1 and 20:5),and n-alkanes (C16-C23) were quantified in the samples.Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions.Adsorption of fatty acids onto cla...     

Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components (14:0, 16:0, 16:1, 18:1 and 20:5), and n-alkanes (C₁₆–C₂₃) were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017–0.024 d⁻¹, 0.049–0.103 d⁻¹ and 0.011 to 0.069 d⁻¹, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.     

Influence of salinity on the early development and biochemical dynamics of a marine fish,Inimicus japonicus

Fertilised eggs of the devil stringer(I nimicus japonicus) were incubated at different salinity levels(21, 25, 29, 33, and 37), and then the hatching performances, morphological parameters, and biochemical composition(protein, lipid and carbohydrate) of the larvae were assayed to determine the influence of salinity on the early development of I. japonicus. The tested salinity levels did not af fect the times of hatching or mouth opening for yolk-sac larvae. However, the salinity significantly influenced the hatching and survival rates of open-mouthed larvae, as well as the morphology of yolk-sac larvae. The data indicated that 30.5 to 37.3 and 24.4 to 29.8 were suitable salinity ranges for the survival of embryos and larvae of I. japonicus, respectively. Larvae incubated at a salinity level of 29 had the greatest full lengths, and decreasing yolk volume was positively correlated with the environmental salinity. With increasing salinity, the individual dry weights of newly hatched larvae or open-mouthed larvae decreased significantly. Newly hatched larvae incubated at a salinity level of 29 had the greatest metabolic substrate contents and gross energy levels, while the openmouthed larvae's greatest values occurred at a salinity level of 25. Larvae incubated in the salinity range of 33 to 37 had the lowest nutritional reserves and energy values. Thus, the I. japonicus yolk-sac larvae acclimated more readily to the lower salinity level than the embryos, and higher salinity levels negatively influenced larval growth and development. In conclusion, the environmental salinity level should be maintained at 29–33 during embryogenesis and at 25–29 during early larval development for this species. Our results can be used to provide optimum aquaculture conditions for the early larval development of I. japonicus.     

EFFECTS OF DCMU ON CHLOROPHYLL FLUORESCENCE RATIO F685/F735 IN MARINE RED,BROWN AND GREEN ALGAE

The chorophyll fluorescence ratio F685/F735 in vivo can be a useful indicator for stress detection inhigher plants and seaweed. DCMU [3 - (3, 4 - dichlorophenyl ) - 1, 1 - dimethylurea] treatment influencesthis ratio. Th effects of DCMU on F685/F735 of marine red, brown and green algae under excitationlight of different wavelengths were investigted. In the brown algae, Laminaria japonica and Undariapinnatifida,DCMU did not increase this ratio under blue light excitation but increased the ratio slightlyunder excitation by green light. For the red algea, Halymenia sinensis, DCMU increased the ratiomarkedly under both blue and green ligh excitation. The percentage increase could reach 50% (undergreen light excitation) and was due to unequal enhancement at the two emission maxima by DCMU. Afraction of chlorophyll which contributed to fluorescence in the 735 nm region was less sensitive toDCMU and was likely from photosystem I of red algae. In the green alga, Ulva pertusa, DCMU causeda slight increase in F685     

Response of benthic algae to environmental conditions in an urban lake recovered from eutrophication,China

Journal of Oceanology and Limnology - Benthic algae communities dominate the primary production in littoral zone of shallow lake. To understand the long-term effect of alteration in the composition...     

Physiological changes of submerged macrophytes in response to a floating filamentous green algae bloom in clear-water conditions

The aim of this study was to evaluate the physiological responses of a submerged macrophyte to a floating fi lamentous green algal bloom in clear-water conditions.Elodea nuttallii was grown with floating Cladophora sp.at four diff erent levels(0,control;140,280,560 g FW/m ~2)in an outdoor experimental system,and its photosynthetic and antioxidant systems were evaluated.The presence of floating Cladophora sp.signifi cantly changed the water environment by decreasing light intensity and increasing dissolved oxygen and the pH value.The photosynthetic parameters of E.nuttallii(e.g.?F/F _m~￠,F _v/F _m,total chlorophyll)were higher in the presence of floating Cladophora sp.than in the control at the beginning of experiment.Because of the increasing dissolved oxygen concentration and pH value,the values of these indicators decreased(except for photosynthetic pigments)during the experiment.Compared with E.nuttallii in the control,E.nuttallii growing in the presence of floating Cladophora sp.showed higher malondialdehyde content,catalase activity,and peroxidase activity.The biomass of E.nuttallii was decreased by about 30% in the presence of high biomasses of floating Cladophora sp.(280 and 560 g FW/m ~2).These results suggest that floating Cladophora had complex eff ects on the biomass of E.nuttallii and that changes in water quality resulting from floating Cladophora sp.may be more important than its direct shading eff ect.