P-31 in-vivo NMR investigation on the function of polyphosphates as phosphate-and energysource during the regreening of the green alga Chlorella fusca

The green alga Chlorella fusca accumulates polyphosphates under conditions of nitrogen starvation while deassembling the photosynthetic apparatus. The polyphosphate content of cells regreening after resupply with nitrate under different culture conditions was investigated by P-31 in-vivo NMR spectroscopy. Neither phosphate deficiency nor anaerobiosis during the first hours of regreening inhibited the recovery of the cells. Polyphosphates were degraded during regeening. Differences in the amount of polyphosphates of phosphate supplied and deficient cells occurred only after more then 8 h. After 16 h phosphate deficient cells had still 75% of the polyphosphate content of phosphate suppled cells. In cells kept under anaerobic conditions polyphosphate degradation was much higher than in oxygen supplied cells. After 8 h they contained less than 50% of the polyphosphate content of oxygen supplied cells. These data suggest that polyphosphates serve as obligatory phosphate source during regreening and may be used as an energy source.Non standard abbreviations EDTA Ethylene diamine tetraacetic acid - FID Free induction decay - MOPSO 3-(N-morpholine)-2-hydroxy-propanesulfonic acid - NMR Nuclear magnetic resonance - PP Polyphosphates - PP₄ central phosphate groups of polyphosphates     

ULTRASTRUCTURE AND ECOLOGY OF AUREOCOCCUS ANOPHAGEFERENS GEN. ET SP. NOV. (CHRYSOPHYCEAE): THE DOMINANT PICOPLANKTER DURING A BLOOM IN NARRAGANSETT BAY,RHODE ISLAND,SUMMER 19851

Observations of a marked cessation of feeding in filter feeding animals maintained in flowing Narragansett Bay seawater in June 1985 drew our attention to a bloom of a golden alga 2 μm in diameter at unprecedented populations of 10⁹ cells. L^?1. This picoplankter lacked morphological features useful in discriminating it from other similar sized forms with either phase contrast or epifluorescence light microscopy. Natural populations of picoplankton, obtained from the height of the bloom until its decline, were examined in thin section with transmission electron microscopy. A cell with a single chloroplast, nucleus, and mitochondrion and an unusual exocellular polysaccharide-like layer was apparently the bloom alga. The ultrastructure of this alga is consistent with that of the Chrysophyceae, and a new genus and species, Aureococcus anophagefferens is described. Attempts to grow this previously unrecognized picoplanktonic alga as an obligate phototroph failed and only yielded cultures of other previously described picoalgae. Facultative and obligate phagotrophic protists with ingested cells of Aureococcus were only observed as the bloom waned and minute diatoms became common. Cells of A. anophagefferens with virus particles typical for picoalgae occurred throughout the bloom. Populations of the usually dominant photosynthetic picoplankter, the cyanobacterium Synechococcus Nägeli, were depressed during the bloom. This could be due in part to selective grazing on Synechococcus rather than Aureococcus by elevated populations of Calycomonas ovalis Wulff which accompanied the algal bloom.     

N-15 in vivo NMR spectroscopic investigation of nitrogen deprived cell suspensions of the green alga Chlorella fusca

The possibility to apply N-15 in vivo NMR spectroscopy to study algal N-metabolism has been investigated. N-15 labelled cells of the green alga Chlorella fusca, subjected to nitrogen starvation and N-14 labelled cells supplied with K¹⁵NO₃ after prolonged nitrogen starvation were monitored by N-15 in vivo NMR spectroscopy at different times after the change in their nitrogen supply. During 20–40 min, necessary for the acquisition of 1 spectrum, the cells were under dark anaerobic conditions, but the relative amounts of the metabolites detected did not change. Signals from 2 acid amides, from the side chain nitrogens of arginine and lysine, from prolin as well as 4 signals from α amino groups of amino acids were detected. Besides two signals not yet reported in the literature were found. They may be due to amino compounds, but not to amino acids. The amount of free amino acids in the cells increases not only upon resupply of nitrogen starved cells with nitrate but also during the first hours after nitrate depletion. The spectra obtained from N-15 labelled autospores show that N-15 in vivo NMR spectroscopy can be applied to the investigation of N metabolism of the cells.     

Cellular localization of cytochrome c 553 in the N2-fixing cyanobacterium Anabaena variabilis

The in situ location of the electron carrier protein cytochrome C ₅₅₃ (cyt c ₅₅₃) has been investigated in both vegetative cells and heterocysts of the cyanobacterium Anabaena variabilis ATCC 29413 using the antibody-gold technique, carried out as a post-ernbedding immunoelectron microscopy procedure. When using a rabbit polyclonal anti-cyt c ₅₅₃ specific antiserum an intense labelling, associated mainly with the cell periphery (cytoplasmic membrane and periplasmic area), was seen in both heterocysts and vegetative cells. The selective release of most of the cellular cyt c ₅₅₃ during a Tris-EDTA treatment confirms a periplasmic localization of this protein in A. variabilis. The results indicate that most of cyt c ₅₅₃ is located in the periplasmic space. The roles ascribed to this protein in both respiration and photosynthesis in cyanobacteria are discussed.Abbreviations Cyt c ₅₅₃ cytochrome c ₅₅₃ - PBS phosphate buffered saline (20 mM sodium phosphate, 0.9% NaCl, pH 7.4) - PMSF phenylmethylsulfonyl fluoride Recipient of a Research Fellowship of the Alexander von Humboldt Foundation (Bonn, FRG) for a leave to the University of Konstanz.     

Transport of leucine in the cyanobacterium Anabaena variabilis

The amino acid leucine was transported by the cyanobacterium Anabaena variabilis. The K _m for transport was 10.8 M; the V _max was 8.7 nmoles min^–1 mg^–1 chlorophyll a. Transport of leucine was energy dependent: uptake of leucine was inhibited in the dark, and by DCMU and cyanide. Transport was neither dependent on nor enhanced by Na⁺. Prior growth of cells with leucine did not repress transport of [¹⁴C]-leucine. Alanine, glycine, valine, and methionine were strong competitive inhibitors of leucine uptake; serine, threonine, isoleucine, norleucine, and d-alanine competitively inhibited to a lesser degree. Other amino acids or amino acid analogues, including d-leucine, -aminoisobutyrate, and d-serine did not inhibit the transport of leucine.Abbreviations Chl a chlorophyll a - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - TES N-tris(hydroxymethyl)-2-aminoethane-sulfonic acid - TCA trichloroacetic acid - Tris N-tris(hydroxymethyl)aminoethane     

Inorganic-carbon uptake by a small-celled strain of Stichococcus bacillaris

Air-grown cells of a marine, small-celled (2 m diameter) strain of Stichococcus bacillaris contained appreciable carbonic-anhydrase activity but this was repressed when cells were grown on air enriched with 5% (v/v) CO₂. Assay of carbonic-anhydrase activity using intact cells and cell extracts showed all activity was intracellular in this Stichococcus strain. Measurement of inorganic-carbon-dependent photosynthetic O₂ evolution at pH 5.0, where CO₂ is the predominant form of inorganic carbon, showed that the concentration of inorganic carbon required for half-maximal rate of photosynthetic O₂ evolution [K_0.5(CO₂)] was 4.0 M for both air- and CO₂-grown cells. At pH 8.3 the K_0.5(CO₂) was 0.3 mM for air-grown and 0.6 mM for CO₂-grown cells. Sodium ions did not enhance bicarbonate utilization. Measurement of the internal inorganic-carbon pool (HCO ₃ ^– +CO₂) by the silicone-oil-layer centrifugal filtering technique showed that air- and CO₂-grown cells were able to concentrate inorganic carbon up to 20-fold in relation to the external medium at pH 5.0 but not at pH 8.3. In this alga the high affinity for CO₂ and inorganic-carbon accumulation in CO₂- and air-grown cells results from active CO₂ transport that is not dependent on carbonic-anhydrase activity.Abbreviation Hepes 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid     

蓝藻原生质球研究的现状及存在问题

在原生质体(球)技术方面,蓝藻也许是一种最为困难的材料了。蓝藻原生质球的研究工作起步不算很晚,但进展不快。直到现在,作为一项可以用于遗传操作的基本技术还没有建立起来。这主要表现在,原生质球的再生问题没有解决;此外,在基本分离制备方面也存在不少问题。而对于植物、真菌、细菌、放线菌和绿藻,这些问题都早已     

青霉素对蓝藻细胞的作用

1967年,Biggins首次报道通过溶菌酶处理获得了有生活力的篇藻(Phormidium luridum)原生质球。此后,虽然许多作者在这方面作了不少工作,但原生质球的再生和融合问题至今没有得到解决。再生和融合与分离制备方法密切相关,因此,     

1H- and13C-NMR spectroscopic studies of lipid extracts of the red algaGracilaria longa

Lipid extracts of the red algaGracilaria longa were studied by¹H- and¹³C-NMR spectroscopy. Peaks in the¹³C-NMR spectra attributable to sterols, chlorophylls and carotenoids allowed free and acylated cholesterol, chlorophylla and lutein to be identified as the most abundant components of these classes. A content of 0.5 ± 0.1 μmoles of total cholesterol/g wet alga was estimated from the¹H-NMR spectrum, which also allowed the determination of the phosphatidylcholine/total lipid molar ratio (9.5 ± 0.5%). The¹³C-NMR spectroscopic experiments provided information on the position of the double bonds on the fatty acid residues. A comparison between NMR spectra of lipid extracts obtained for wet and dried alga showed that the alga undergoes both a dramatic peroxidation and some glycolipid degradation during the drying process.