Ultrastructure of Blue-Green Algae

Two freshwater blue-green algae, Tolypothrix tenuis and Fremyella diplosiphon, and an oscillatorialike marine alga, were found to possess structures on the photosynthetic lamellae which appear to correspond to the phycobilisomes of red algae. These homologous structures are important because they contain the phycobilins which are accessory pigments involved in photosynthesis. As in the red algae, the phycobilisomes were attached on the outer side of each lamellae, i.e., the side facing away from its own membrane pair. Although our study on Anacystis nidulans has not thus far revealed the presence of phycobilisomes, some observations were made on the structure of the polyhedral bodies. After negative staining, the polyhedral bodies were seen to be composed of regularly spaced subunits arranged in a crystalline array. Elongated segmented rods, which differed from the polyhedral bodies, were found in the nuclear region of apparently healthy Tolypothrix cells.     

Phycobilisomes in Blue-Green Algae

Fifteen species of freshwater blue-green algae, including unicellular, filamentous, and colonial forms, were subjected to a variety of fixatives, fixation conditions, and stains for comparison of the preservation of phycobilisomes. Absorption spectra of the corresponding in vivo and released photosynthetic pigments, in 10 of the species that were maintained in culture, demonstrated the presence of phycocyanin in all 10 species and phycoerythrin in only 2 of them. Spectroscope and electron microscope evidence was obtained for localization of phycobiliproteins in phycobilisomes of Nostoc muscorum. Phycobilisomes were observed in all species examined in situ, strenghening the hypothesis that phycobilisomes are common to all phycobiliprotein-containing photosynthetic blue-green algae.     

Respiration in Blue-Green Algae

The low rate of endogenous respiration exhibited by the blue-green algae Anacystis nidulans and Phormidium luridum was not increased by the addition of respiratory substrates. However, endogenous respiration was inhibited by low concentrations of cyanide and by high carbon monoxide tensions. In addition, the uncouplers dinitrophenol and carbonyl cyanide p-trifluoromethoxyphenylhydrazone both stimulated the respiratory rate. The transition of cells from the aerobic steady state to anaerobiosis was accompanied by a decrease in the concentration of cellular nicotinamide adenine dinucleotide phosphate (NADP(+)) and adenosine triphosphate (ATP), whereas the concentration of nicotinamide adenine dinucleotide (NAD(+)) was unchanged. Concomitant with the metabolite decreases were stoichiometric increases io reduced NADP(+) (NADPH), adenosine diphosphate, and adenosine monophosphate. A decrease in ATP was also observed after the addition of uncouplers. These data are interpreted as evidence for the association of oxidative phosphorylation with the oxidation of NADP(+)-linked substrates in these algae. Membrane fragments isolated from the algal cells oxidized succinate, malate, ferrocytochrome c, ascorbate-tetramethyl-p-phenylenediamine, and reduced 2,6-dichlorophenol indophenol but did not oxidize NADPH or reduced NAD(+) in a cyanide-sensitive system. Oxidative phosphorylation has not yet been demonstrated in these fragments, but a dark ATP-P(i) exchange, distinct from the lighttriggered exchange associated with photosynthesis, is readily observed. This exchange was inhibited by phloridzin, Atabrine, and uncouplers in concentrations which suggest that the mechanism of oxidative phosphorylation in blue-green algae is different from that found in other bacteria and in mitochondria. These results led to the conclusion that the biochemical basis for obligate autotrophy in these organisms does not lie in the metabolic events associated with terminal electron transport and energy conservation.     

云南兰科一新种——中华火焰兰

对兰科新种中华火焰兰 (Renanthera sinica)作了描述与绘图。此新种与云南火焰兰 (R.imschootiona)有亲缘关系 ,但本新种叶较狭 ,宽 9～ 11mm,花浅黄色 ,具紫红色的疏斑点 ,侧萼片较狭 ,宽 4.5～ 5 .5 mm,以及唇瓣的中裂片上半部呈半球形囊状 ,甚易区别于云南火焰兰。提供了中国火焰兰属的分种检索表。     

Photooxidative Death in Blue-Green Algae

When incubated in the light under 100% oxygen, wild-type blue-green algae (Anacystis nidulans, Synechococcus cedrorum) die out rapidly at temperatures of 4 to 15 C, and at 35 C (or at 26 C in the case of S. cedrorum) in the absence of CO(2). Photosynthesis is impaired in these cells long before they die. Blocking of photosystem II at high temperatures in the presence of CO(2) sensitizes the algae to photooxidative death. Photooxidative death and bleaching of photosynthetic pigments are separable phenomena. Photooxidative conditions were demonstrated in Israeli fish ponds using A. nidulans as the test organism during dense summer blooms, when dissolved CO(2) is low, and in winter, when water temperatures generally drop below 15 C. This finding suggests that photooxidative death may be responsible for the sudden decomposition of blue-green blooms in summer, and may be a factor in the absence of blue-green blooms in winter.     

Lysis of Blue-Green Algae by Myxobacter

Enrichment from local fishponds led to the isolation of a bacterium capable of lysing many species of unicellular and filamentous blue-green algae, as well as certain bacteria. The isolate is an aflagellate, motile rod which moves in a gliding, flexuous manner; the organism is capable of digesting starch and agar, but not cellulose and gelatin. Its deoxyribonucleic acid base pair composition (per cent guanine plus cytosine approximately 70) shows a close resemblance to that of the fruiting myxobacteria. Algae in lawns on agar plates were lysed rapidly by the myxobacter, but only limited and slow lysis occurred in liquid media, and no lysis took place when liquid cultures were shaken. No diffusible lytic factors would be demonstrated. Continuous observation of the lytic process under a phase-contrast microscope suggested that a close contact between the polar tip of the myxobacter and the alga is necessary for lysis. The lytic action is limited to the vegetative cells of the algae, whereas heterocysts are not affected. The gas vacuoles of the algal host are the only remnant visible after completion of digestion by the myxobacter.     

Heterotrophic Growth of Blue-Green Algae in Dim Light

A unicellular blue-green alga, Agmenellum quadruplicatum, and a filamentous blue-green alga, Lyngbya lagerheimíi, were grown heterotrophically in dim light with glucose as major source of carbon and possibly energy. The dim-light conditions did not support autotrophic growth. The two blue-green algae appeared to have the same metabolic block, namely an incomplete tricarboxylic acid cycle, as has been found in other obligately phototrophic blue-green algae. Under dim-light conditions, glucose made a greater contribution to cell constituents (amino acids) of A. quadruplicatum and L. lagerheimii than under high-light conditions.     

Metabolism of delta-Aminolevulinic Acid in Red and Blue-Green Algae

δ-Aminolevulinic acid was incorporated in vivo into C-phycocyanin and B-phycoerythrin in two species of the Rhodophyta (Cyanidium caldarium, Porphyridium cruentum) and three species of the Cyanophyta (Anacystis nidulans, Plectonema boryanum, Phormidium luridum). Amino acid analysis of phycocyanin-¹⁴C from C. caldarium cells which had been incubated with δ-aminolevulinate-4-¹⁴C showed that 84% of the radioactivity incorporated was present in the phycocyanobilin chromophore and less than 16% of the radioactivity cochromatographed with amino acids. These results indicate that δ-aminolevulinate is utilized predominantly via the porphyrin pathway in C. caldarium. Conversely, analysis of phycocyanin-¹⁴C prepared from cells of A. nidulans, P. boryanum, and P. luridum which had been incubated with radiolabeled δ-aminolevulinate demonstrated that 85%, 81%, and 93%, respectively, of the radioactivity incorporated cochromatographed with amino acids. The ratio of incorporated radioactivity in amino acids and phycoerythrobilin was 40:60 in P. cruentum phycoerythrin obtained from cells which had been incubated with δ-aminolevulinate-4-¹⁴C. Succinate-2-3-¹⁴C appeared to be as good a carbon source of amino acids as did C₄ and C₅ of δ-aminolevulinate. These data demonstrate a major alternate route (other than the porphyrin pathway) of δ-aminolevulinate metabolism in red and blue-green algae. The factors responsible for the extent to which δ-aminolevulinate is utilized for synthesis of porphyrins and their derivatives and routes of δ-aminolevulinate catabolism in the organisms employed are discussed.     

Fatty Acid Composition of Unicellular Strains of Blue-Green Algae

The fatty acids of 34 strains of unicellular blue-green algae provisionally assigned to the genera Synechococcus, Aphanocapsa, Gloeocapsa, Microcystis, and Chlorogloea by Stanier et al. have been chemically characterized. The strains analyzed can be divided into a series of compositional groups based upon the highest degree of unsaturation of the major cellular fatty acids. Twenty strains fall into the group characterized by one trienoic fatty acid isomer (alpha-linolenic acid), and seven strains fall into a group characterized by another trienoic acid isomer (gamma-linolenic acid). These groups in many cases correlate well with groupings based upon other phenotypic characters of the strains, e.g., deoxyribonucleic acid base composition. The assignment of a strain to a compositional group is not altered when the strain is grown under a variety of different culture conditions. All strains contain glycolipids with the properties of mono- and digalactosyldiglycerides.     

拟衣藻属一新种——中华拟衣藻及其生活史的研究

报道了团藻目衣藻科拟衣藻属一新种。此种从中国科学院武汉植物研究所一浇园粪缸中采得,在分离室内单种培养过程中,对其形态学和生活史进行了研究。营养细胞具有多个盘状色素体,与拟衣藻属已知的种类有明显的差别。经培养观察,作者发现除细胞分裂、无性生殖外,还有同宗异配式有性生殖,在生活史各阶段该藻中绿体中均未见蛋白核,因此,拟衣藻作为分类单元是一个有效的属。     

The Effect of pH on Copper Toxicity to Blue-Green Algae

The effect of pH on copper toxicity to two planktonic blue-green algae, Aphanizomenon gracile and Oscillatoria redekei, was investigated. Growth rates of the algae without copper treatment decrease with pH, Aphanizomenon is earlier and more affected than Oscillatoria. On the other hand, pH-lowering leads sooner to a toxicity enhancement in Oscillatoria. In the acid range, toxicity retardation occurs in Aphanizomenon. At pH 5.1, shortening of the interval between copper toxicity and copper stimulus is characteristic for both species.     

Interaction of Two Populations of the Blue-Green Algae in Co-Culture

Interaction of the populations of two species of blue-green algae Tolypothrix tenuis and Anabaena variabilis "1058", in mixed culture, was observed in three different ways: (1) The growth competition was studied in mixed-culture, where the two species grew in one batch of culture. (2) The effect of the filtrate, the extracellular products, from the culture of one species on the growth of the other species was studied. (3) In fitrated culture, two algal species were cultivated separately in either side a U-form container partitioned by a micro-pore membrane in the middle. The extracellular products were permeable through the membrane from one side to the other side. The influonce of the biologically active substances prosduced by the algae at different growth stages can be observed and estimated. The growth was measured by dry weight of biomass andchlorophyll-a content. The proportion of components of phycobiliprotein (e. g. ratio of phycocyanin to phycoerythrin) was estimated as the specific growth rate of two blue-greens in the mixed cultures. 1. The results obtained are summarized as follows. There were three types of the bioactivity of the extracellular products: (1) The lethal effects on each other caused the by the lethal agents of these two blue-greens were different. (2) The suppressive effects on growth by each other in one community were also found. (3) Effect on growth promotion exhibited only in the extracellular products of A. variabilis "1058". 2. The results indicate that there occur a direct competitive interaction of two populations. This Competition was controlled by the bio-active substances of the extracellular products which might regulate the structural composition and inturn, the succession of the comunity.     

The Comparative Boron Nutrition of Several Green and Blue-Green Algae

The boron requirements of filamentous and non-filamentous species of green and blue-green algae have been investigated. A primary feature of this study was the quantitative analysis of the cells for boron. This permitted expression of the degree of purification of the environment and the boron requirements of the organisms in terms of cell content. Three species of green algae were shown neither to require boron nor to absorb it in appreciable amounts. In contrast, three species of blue-green algae readily absorbed boron and nitrogen fixing species showed a marked growth response to boron when nitrate was omitted from the culture medium. The response to boron was less with nitrate in the medium, probably due to increased contamination from the nitrate salt rather than an involvement of boron in the fixation process. The boron content of the deficient blue-green algae was 1–2 μg/g, suggesting a requirement below dicot angiosperms and comparable to monocots. In agreement with other reports, the fungus Penicillium chrysogenum neither required nor absorbed boron.