Foliar characteristics,cambial activity and wood formation in Azadirachta indica A. Juss. as affected by coal–smoke pollution

This study, aimed at elucidating changes in the foliar and cambial behavior in Azadirachta indica (Neem tree) due to coal-smoke pollution, has revealed inhibitory effects of pollution stress on leaf pigments concentrations, nitrate reductase activity and the contents of reducing sugars and total N content, whereas stimulatory effects were given on stomatal index and nitrate and sulphur contents. Under smoke effects, stomatal conductance was low, leading to a drop in the net photosynthetic rate and a rise in the internal CO₂ concentration of leaf. Cambial reactivation in the stem was delayed at the polluted site. Although the total span of the cambial activity was reduced, greater amount of wood was observed to accumulate in the stem axis under heavy pollution stress. Vessel proportion in the wood increased, whereas size of vessel elements and xylem fibers decreased. “Vulnerability factor” (ratio between mean vessel diameter and mean vessel abundance) and “mesomorphic ratio” (multiplication product of vulnerability factor and mean length of vessel element) of the stem–wood, both declined with increase in the pollution stress, thus indicating a tendency of the species for shifting towards xeromorphy when grown under stress. Given the opposite trends of photosynthetic rate and wood increment, the carbon-partitioning pattern rather than the photosynthetic rate seems to have influenced the accumulation of new wood. The Neem tree proves to be suitable for growing in the polluted areas.     

Marine Pseudoalteromonas species are associated with higher organisms and produce biologically active extracellular agents

The newly established genus Pseudoalteromonas contains numerous marine species which synthesize biologically active molecules. The production of a range of compounds which are active against a variety of target organisms appears to be a unique characteristic for this genus and may greatly benefit Pseudoalteromonas cells in their competition for nutrients and colonization of surfaces. Species of Pseudoalteromonas are generally found in association with marine eukaryotes and display anti-bacterial, bacteriolytic, agarolytic and algicidal activities. Moreover, several Pseudoalteromonas isolates specifically prevent the settlement of common fouling organisms. While a wide range of inhibitory extracellular agents are produced, compounds promoting the survival of other marine organisms living in the vicinity of Pseudoalteromonas species have also been found.     

海南岛海水鱼类单殖吸虫研究Ⅴ——鲻鱼虫属一新种记述

在大鳞Ｌｉｚａｍａｃｒｏｌｅｐｉｓ鳃上检获到鲻鱼虫属１新种,小钩鲻鱼虫,新种ＬｉｇｏｐｈｏｒｕｓｈａｍｕｌｏｓｕｓＰａｎ＆Ｚｈａｎｇ,ｓｐ．ｎｏｖ．。以其后吸器两对中央大钩的形态结构以及背、腹中央大钩量度上的差异,背联结片的结构和交接器形态结构不同而区别于ＬｉｇｏｐｈｏｒｕｓｉｍｉｔａｎｓＥｕｚｅｔ＆Ｓｕｒｉａｎｏ,１９７７。     

Significance of Na+ in the fish pathogen, Vibrio anguillarum, under energy depleted condition

Vibrio anguillarum kills various kinds of fish over salinities ranging from seawater to freshwater. In this study, we investigated the role of Na(+) in V. anguillarum, especially under energy-depleted conditions such as in natural seawater. V. angustum S14, which is a typical marine vibrio, was used for comparison. V. anguillarum only required Na(+) for starvation-survival, but in contrast, V. angustum S14 always required Na(+) for both growth and starvation-survival. In marine vibrios, Na(+) is used in the Na(+)-dependent respiratory chain that produces the sodium motive force (SMF) across the cell membrane. It has been considered that marine vibrios always need a SMF produced by Na(+), however in the case of V. anguillarum, the SMF is not required for growth, but becomes more important for starvation-survival.     

The effects of mixotrophy on the stability and dynamics of a simple planktonic food web model

Recognition of the microbial loop as an important part of aquatic ecosystems disrupted the notion of simple linear food chains. However, current research suggests that even the microbial loop paradigm is a gross simplification of microbial interactions due to the presence of mixotrophs-organisms that both photosynthesize and graze. We present a simple food web model with four trophic species, three of them arranged in a food chain (nutrients-autotrophs-herbivores) and the fourth as a mixotroph with links to both the nutrients and the autotrophs. This model is used to study the general implications of inclusion of the mixotrophic link in microbial food webs and the specific predictions for a parameterization that describes open ocean mixed layer plankton dynamics. The analysis indicates that the system parameters reside in a region of the parameter space where the dynamics converge to a stable equilibrium rather than displaying periodic or chaotic solutions. However, convergence requires weeks to months, suggesting that the system would never reach equilibrium in the ocean due to alteration of the physical forcing regime. Most importantly, the mixotrophic grazing link seems to stabilize the system in this region of the parameter space, particularly when nutrient recycling feedback loops are included.     

Isolation and sequencing of the replication region of plasmid pBFp1 isolated from a marine biofilm

A 24 kb plasmid, pBFp1, encoding mercury resistance was previously isolated from a marine biofilm. Isolation and sequencing of a 4280 bp DNA fragment containing the plasmid replicon (rep-pBFp1) revealed a putative open reading frame encoding a RepA protein and an oriV-like region containing an A+T rich sub-region, iterons, and DnaA boxes. Sequence comparisons showed significant similarities to the incW plasmid pSa both for the RepA amino acid sequence and in the iteron DNA sequence. Plasmid pBFp1 was also shown to be incompatible with pSa in standard incompatibility testing. A probe from the repA gene of pBFp1 was further made and tested on a collection of plasmids exogenously isolated from marine habitats in a previous study.     

Quantitative analysis of bacterial communities from Mediterranean sapropels based on cultivation-dependent methods

Microbial communities of ancient Mediterranean sapropels, buried sediment layers of high organic matter, were analyzed by most probable number (MPN) approaches. Mineral media containing different carbon sources in sub-millimolar concentrations were used. MPN numbers were elevated in sapropels and at the sediment surface, which mirrored total cell count distributions. Highest MPN counts were obtained with a mixture of different monomeric and polymeric substrates, with amino acids or with long-chain fatty acids as sole carbon sources. These values reached up to 2 x 10(7) cm(-3), representing 3.3% of the total cell count. A total of 98 pure cultures were isolated from the highest positive dilutions of the MPN series, representing the most abundant microorganisms culturable by the methods used. The strains were identified by molecular biological methods and could be grouped into 19 different phylotypes. They belonged to the alpha-, beta-, gamma-, and delta-Proteobacteria, to the Actinobacteria and the Firmicutes. However, about half of the number of isolates was closely related to the genera Photobacterium and Agrobacterium. Regarding the high cultivation success, these organisms can be assumed to be typical sapropel bacteria, representing a substantial part of the culturable indigenous microbial community.     

Characterization of xenobiotic-metabolizing cytochrome P450 (CYP) forms in ringed and grey seals from the Baltic Sea and reference sites

Earlier studies have shown that members of the cytochrome P4501 (CYP1) enzyme family are constitutively expressed, and are elevated in the livers of ringed seals (Phoca hispida) and grey seals (Halichoerus grypus) living in the heavily polluted Baltic Sea. In this study, we compared the expression profiles of several additional CYP enzymes in the liver and extrahepatic tissues of Baltic ringed and grey seals with the corresponding CYP expression in seals from relatively unpolluted waters. We used marker enzyme activity levels, diagnostic inhibitors and immunoblot analysis to assess members of the CYP2A, CYP2B, CYP2C, CYP2D, CYP2E and CYP3A sub-families. Coumarin 7-hydroxylation (COH), a marker of CYP2A activity, was high in the liver and the lungs of all the studied seal populations. The presence of a putative CYP2A form in these seals was further supported by the strong inhibition of COH activity by a chemical inhibitor and by an anti-CYP2A5 antibody. However, antibodies to human and rodent CYP2B, CYP2C and CYP2E forms did not recognize any proteins in these seal species. Dextromethorphan O-demethylation (marker for CYP2D activity) and chlorzoxazone 6-hydroxylation (marker for CYP2E activity) were measurable in the livers of all the seals we studied. Both activities were elevated in the Baltic seal populations, showed a strong positive correlation with CYP1A activity and were at least partly inhibited by a typical CYP1A inhibitor, alpha-naphthoflavone. Further studies are needed to determine the presence and characteristics of CYP2D and CYP2E enzymes in ringed and grey seals. Testosterone 6beta-hydroxylation, a CYP3A marker, showed a relatively high level of activity in the livers of both seal species and was potently inhibited by ketoconazole, a CYP3A-selective inhibitor. The putative CYP3A activity showed an opposing geographical trend to that of CYP2D and CYP2E, since it was elevated in the control area. CYP3A protein levels, revealed by immunoblotting, showed a positive correlation with testosterone 6beta-hydroxylation. We conclude tentatively that CYP2A- and CYP3A-like enzymes are expressed in ringed and grey seals, but that CYP2B- and CYP2C-like ones are not. Further information on the individual contaminant profile is needed before any conclusions can be drawn on a possible connection between the varying CYP expressions and the contaminant load.     

Long chain polyunsaturated fatty acid production and partitioning to triacylglycerols in four microalgae

Gas chromatographic profiling of fatty acids was performed during the growth cycle of four marine microalgae in order to establish which, if any, of these could act as a reliable source of genes for the metabolic engineering of long chain polyunsaturated fatty acid (LC-PUFA) synthesis in alternative production systems. A high-throughput column based method for extraction of triacylglycerols (TAGs) was used to establish how much and at what stage in the growth phase LC-PUFAs partition to storage lipid in the different species. Differences in the time course of production and incorporation of docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) into TAGs were found in the marine microalgae Nannochloropsis oculata (Eustigmatophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae), and the Haptophyte Pavlova lutheri. Differences were not only observed between species but also during the different phases of growth within a species. A much higher percentage of the total cellular EPA was partitioned to TAGs in stationary phase cells of N. oculata compared to P. tricornutum. Although P. tricornutum produces DHA it does not partition it to TAGs. Both T. pseudonana and P. lutheri produce EPA and DHA and partition these to TAGs during the stationary phase of growth. These two species are therefore good candidates for further biochemical and molecular analysis, in order to understand and manipulate the processes that are responsible for the incorporation of LC-PUFAs into storage oils.     

活性X-3B红染料在水-土壤-作物连续体中的迁移模型研究

进入环境的自学成才性X-3B红染料是一典型的持久性有机污染物（POPs)。它从水分室向土壤分室再到作物分室的迁移,是一连续的生态过程,基于此,从理论上对活性X-3B红染料在水-土壤两相,土壤-作物两相以及水-土壤-作物整个连续体中的迁移进行了定量描述与探讨,并采用棕壤-大豆、褐土-小麦,红壤-萝卜和水稻土-水稻等系统给予了实验论证,表明活性X-3B红染料通过吸附机制从水分室到土壤分室的迁移符合Langmuir模型。通过作物根系吸收机制从土壤分室到作物分室的迁移可以用对数化的作物-土壤积累因子（CSAF）模型予以定量描述。