An inventory of factors that affect polysaccharide production by Phaeocystis globosa

Phaeocystis material contains polysaccharides that are built from at least eight different monosaccharides. Differences have been reported between the carbohydrate composition of different Phaeocystis species, and also between samples taken from Phaeocystis globosa blooms in different areas. In order to elucidate factors that could play a role in determining variation in carbohydrate composition and production, a number of Phaeocystis globosa strains were studied under laboratory conditions. Although there was a clear distinction of a northern and a southern cluster in the Phaeocystis globosa strains based on RAPD analysis, the differences in the composition of the mucopolysaccharides were relatively small. The contribution of glucose, however, ranged from 7–85% of total sugars. A strain that was cultured in seawaters of diverse origin produced polysaccharides of a different composition, suggesting the effect of environmental factors. The presence of bacteria affected neither the amount, nor the composition of the carbohydrates that were produced by Phaeocystis globosa. Glucose is part of both the intracellular polysaccharide pool and of the mucopolysaccharides in the colony matrix. Using specific digestion of the intracellular chrysolaminaran by laminarinase, the distribution of polysaccharides over different pools could be assessed. During growth of an axenic, mucus-producing strain, the portion of glucose present as chrysolaminaran appeared to increase. The polyglucose that was not digested by laminarinase remains unidentified. This study shows that environmental factors rather than strain differences determine differences in the sugar composition of Phaeocystis globosa, especially with respect to the glucose content of the material. A difference in the contribution of glucose could be correlated to the portion of cells in the culture that are not in the colonies. Our study emphasises that for studying polysaccharide dynamics in Phaeocystis globosa it is important to be able to discriminate between the different polysaccharide pools. Preliminary results of an enzymatic approach were promising     

Growth Dynamics in Posidonia oceanica (L.) Delile

Abstract. Amounts of photosynthate in the rhizomes, in photosynthetically inactive basal parts of the leaves and different old leaf blades were examined. Winter leaf growth was supported by mobilisation of starch in the rhizome. This winter growth enables Posidonia oceanica to utilize the increased energy influx in early spring via the substantial leaf area already developed and to approach highest productivity in spring. During summer and autumn considerable concentrations of soluble carbohydrates were found in the leaves and rhizomes. Starch was stored in the rhizomes in concentrations of up to 6.8 % of dry weight. Levels of nitrogen and free amino acids were correlated with growth rates. The percentage of total nitrogen present as free amino acid-nitrogen decreased from November (35 %) to summer (less than 1 %), by which time leaf growth had stopped. In contrast to this, amounts of organic anions were low in winter and spring and reached their maximum in summer.
Within a shoot, sites of leaf growth were characterized by high amounts of total nitrogen and free amino acids (innermost leaves), while carbon Fixation was highest in the leaves #2–#4. Particularly high concentrations of soluble carbohydrates were found midway along leaf blades.
It is evident that this unusual growth rhythm of Posidonia oceanica was only possible because of the ability to store considerable amounts of carbon and nitrogen in the rhizomes.
The results of this investigation demonstrate on the one hand that the chemical composition of the plant is strongly correlated with growth and production, and on the other hand that it is dependent on environmental factors, such as energy influx and temperature, which change with season.     

Effects of flooding on the amino acid and carbohydrate patterns of Phragmites australis

Changes in the contents and composition of dissolved amino acids and carbohydrates were monitored in different Phragmites australis stands in Germany. Four different reed clones planted in 1997 in a degraded fen area in NE-Germany were compared with respect to the seasonal development in the total amount of amino acids and sugars in the basal culm internodes. The individual Phragmites clones showed significant differences in the absolute content of both parameters indicating an influence of the genotype. Flooding affected the ratio of amino acids to carbohydrates within the reed clones. Plants grown in flooded parts of the fen area revealed a significantly higher total amino acid content together with a lower total content of carbohydrates.Furthermore, the effects of extreme flooding on the content and composition of amino acids and carbohydrates in the basal culm internodes of Phragmites australis were studied in nine reed stands with different degrees of damage on Lake Constance. Shoots from extremely damaged reed stands were characterised by a significant decrease in the total content of carbohydrates, an increase in the total content of amino acids and an increase in the share of γ-aminobutyric acid. These changes in the content and composition of carbohydrates and amino acids were discussed with respect to their value as stress indicators, such as for oxygen deprivation which causes a hypoxic metabolic state in Phragmites australis stands.     

Seasonal variations and distributions of dissolved free and total carbohydrates at the İzmir Bay, Aegean Sea

Seasonal variations and distributions of dissolved carbohydrate concentrations at the İzmir Bay were investigated with salinity, chlorophyll a (Chl a), and dissolved organic carbon (DOC) levels to understand their relationships. Samples were collected from surface, subsurface and bottom depths at seven stations. DOC concentrations ranged from 32.2 to 244.2 μmol/L, and in general, DOC levels increased from winter to summer, then slightly decreased in autumn. Monosaccharide (MCHO), polysaccharide (PCHO) and total dissolved carbohydrate (TDCHO) levels were found between 0.7-8.3, 0.7-19.5, and 2.6-24.6 μmol/L. DOC, MCHO, PCHO and TDCHO levels were found higher in middle-inner bays, under the influence of anthropogenic inputs, compared to outer bay. Seasonal changes of MCHO/DOC, PCHO/DOC and TDCHO/DOC ratios were statistically significant (p<0.05) and the ratios showed decrease trends from winter to summer-autumn seasons. Distributions of TDCHO/DOC ratios at wide ranges (2.5%-42.3%) indicated the presence of newly forming and degrading fractions of DOM. According to results of factor analysis, Chl a, MCHO and TDCHO were explained in the same factor groups. In conclusion, the results showed that dissolved carbohydrate levels in the İzmir Bay might be influenced by biological processes and terrestrial/anthropogenic inputs.     

Biochemical adaptation of phytoplankton to salinity and nutrient gradients in a coastal solar saltern,Tunisia

The distribution of protein and carbohydrate concentrations of the particulate matter (size fraction: 0.45–160 μm) was studied, from 22 January 2003 to 02 December 2003, in three ponds of increasing salinity in the Sfax solar saltern (Tunisia). The coupling of N/P: DIN (DIN = NO₂⁻ + NO₃⁻ + NH₄⁺) to DIP (DIP = PO₄³⁻) with P/C: protein/carbohydrates ratios along salinity gradient allowed the discrimination of three types of ecosystems. Pond A1 (mean salinity: 45.0 ± 5.4) having marine characteristics showed enhanced P/C ratios during a diatom bloom. N/P and P/C ratios were closely coupled throughout the sampling period, suggesting that the nutritional status is important in determining the seasonal change in the phytoplankton community in pond A1. In pond A16 (mean salinity: 78.7 ± 8.8), despite the high nitrate load, P/C ratios were overall lower than in pond A1. This may be explained by the fact that dinoflagellates, which were the most abundant phytoplankton in pond A16 might be strict heterotrophs and/or mixotrophs, and so they may have not contributed strongly to anabolic processes. Also, N/P and P/C ratios were uncoupled, suggesting that cells in pond A16 were stressed due to the increased salinity caused by water evaporation, and so cells synthesized reserve products such as carbohydrates. In pond M2 (mean salinity: 189.0 ± 13.8), P/C levels were higher than those recorded in either pond A1 or A16. N/P and P/C were more coupled than in pond A16. Species in the hypersaline pond seemed paradoxally less stressed than in pond A16, suggesting that salt-tolerant extremophile species overcome hypersaline constraints and react metabolically by synthesizing carbohydrates and proteins.     

Phylogenetic diversity of carbohydrate degrading culturable bacteria from Mandovi and Zuari estuaries,Goa, west coast of India

Coastal and estuarine waters are highly productive and dynamic ecosystems. The complex carbohydrate composition of the ecosystem would lead to colonisation of microbial communities with abilities to produce an array of complex carbohydrate degrading enzymes. We have examined the abundance and phylogenetic diversity of culturable bacteria with abilities to produce complex carbohydrate degrading enzymes in the Mondovi and Zuari eustauri. It was interesting to note that 65% of isolated bacteria could produce complex carbohydrate degrading enzymes. A majority of these bacteria belonged to Bacillus genera followed by Vibrio, Marinobacter, Exiquinobacterium, Alteromonas, Enterobacter and Aeromonas. Most abundant bacterial genus to degrade hemicellulose and cellulose were Bacillus and Vibrio respectively. Most abundant bacterial genus to degrade hemicellulose and cellulose were Bacillus and Vibrio respectively. It was seen that 46% of Bacillus had ability to degrade both the substrate while only 14% of Vibrio had bifunctionality.     

氮磷添加对黑果枸杞(Lycium ruthenicum)营养器官非结构性碳水化合物特征的影响

非结构性碳水化合物(NSC)在植物生长、繁殖、防御和生存等方面发挥着基础性作用.为探究黑果枸杞(Lyciumruthenicum)NSC积累的器官间规律及其对土壤氮磷供应水平的响应,以3年生黑果枸杞为对象,测定了3个氮磷比例和供应量条件下根茎叶NSC含量.结果表明:(1)黑果枸杞根、茎、叶NSC组成均以可溶性糖为主,淀...     

广东省沿海防潮减灾研究概述

广东濒临南海，海岸线长，热带气旋活动频繁，历史风暴潮灾害严重。例如1969年7月28日的6903号风暴潮在粤东造成严重的灾害；1980年7月22日的8007号台风造成粤西的南渡站最高风暴潮达594cm，是我国有验潮记录以来的最大值(也是西太平洋沿岸国家的最大值)，居世界第5位。针对广东沿海风暴潮灾的主要特点，本文就其防潮减灾提出以下3个观点：(1)深入了解和研究广东省沿海潮灾史，对做好防潮减灾工作具有十分重要的现实意义，同时对防潮减灾规划的制定与沿海防潮工程的设计也具有不可代估的参考价值：(2)做好广东省沿海防潮减灾的工程措施有着同样重要性，一般的防潮工程，甚至高标准防潮堤，在灾难性风暴潮袭击下也会产生一定的风暴潮灾害；(3)加强广东省的非工程防潮措施方面工作和研究，准确及时的风暴潮预报是预防和减轻灾害的主要非工程措施：要求作业人员对经验预报能熟练运用及掌握；普遍推广风暴潮数值预报；开展业务化高分辨率风暴潮漫滩数值预报研究工作。     

冬季中国东海中溶解碳水化合物浓度分布

采集了中国东海(2009-12~2010-01)35个站位的海水样品,其中包括6个站位的垂直断面。用TPTZ方法测定了溶解态的单糖(MCHO)、多糖(PCHO)和总糖(TCHO)的浓度,对其水平分布和PN断面分布进行了研究。结果表明,受到长江冲淡水和黑潮水的影响,表层海水中MCHO、PCHO和TCHO浓度的水平分布表现出由近岸向外海递减的分布趋势。PN断面由于受冬季东北季风的影响,水体混合强烈,使得MCHO、PCHO和TCHO浓度在垂直方向上分层无明显规律。对长江口外3个断面海水中TCHO浓度与环境因子做了相关性研究。结果表明,TCHO浓度与盐度和温度呈显著的线性负相关,与Chl-a浓度呈线性正相关。