Ordovician Calcified Algae and Cyanobacteria, Northern Tarim Basin Subsurface, China

Boreholes between Kuqa and Korla, in the northern Tarim Basin, Xinjiang, penetrated Ordovician marine limestones at depths of 5–6.2km. From three boreholes 54 out of a total of 170 limestone samples contain calcified algae, cyanobacteria and associated Microproblematica. Calcified cyanobacteria (GirvanellaBotomaella, ?Subtifloria) account for 37 per cent of occurrences; green algae (Dasyporelleae and Vermiporella) 28 per cent; Microproblematica (NuiaBevocastriaRothpletzellaHalysis) 20 per cent; and ‘solenoporaceans’ 15 per cent GirvanellaNuia are common in the Early Ordovician deposits, and ‘solenoporaceans’ are abundant in the Mid‐Ordovician. Dasyporelleae and Vermiporella are most abundant in Mid–Late Ordovician samples. Calcified cyanobacteria are common throughout the limestone succession, but particularly in the Mid Ordovician part. MoniliporellaContextaPlexaTexturata, and Villosoporella, hitherto placed in the supposed red algal family Moniliporellaceae Gnilovskaya, are here regarded as dasycladalean green algae. Despite some omissions, this Tarim flora broadly resembles others from Kazakhstan, Baltica and North America, indicating the generally cosmopolitan nature of Ordovician calcified algae and cyanobacteria.     

人表皮生长因子（hEGF）基因在蓝藻中的表达

人表皮生长因子（hEGF)是由53个氨基酸组成的蛋白,在临床上内服与外敷可促进内外表皮细胞的生长。将人工合成的hEGF基因连接到质粒pRL-489上,位于启动子psb下游。验证连接成功后,用三亲接合转移方法将载体pRL-hEGF导入聚球藻Synechococcus sp.PCC7002和鱼腥藻Anabeana sp.PCC7120。由于pRL-hEGF没有能在单细胞蓝藻中自主复制的复制子,通过筛选,hEGF在聚球藻7002中是整合到蓝藻染色体上进行表达的。用PCR扩增的方法在两种转基因藻中均检测到hEGF基因的存在。放射免疫分析证明,hEGF基因在两种转基因藻中均得到了表达。而且,在聚球藻7002中是采用分泌形式将表达产物分泌到培养液中。     

Useful Carriers for Cyanobacteria: Their Response to Cyanobacterial Growth, Acetylene-Reductase Activity, Cyanobacterial Grazers and Paddy Yield in Calcareous Soil

Summary Snails and nematodes, the potential cyanobacterial grazers, differ in their choice for cyanobacterial diet. Snails prefer non-mucilaginous forms while nematodes prefer mucilaginous forms. Such differences in feeding choice between the cyanobacteria suggests that it may not be possible to select strains of diazotrophic cyanobacteria that are resistant to all grazers. The potential consumption of cyanobacteria at an average field density of 20,000 snails ha⁻¹ was estimated to be about 50 kg (fresh weight) ha⁻¹ day⁻¹. Dorylamus sp. was most dominant nematode associated with cyanobacterial consumption. Phytoextracts of neem (Azadirachta indica), bel (Aegle marmelos) and tobacco (Nicotiana tabacum) were effective in controlling these cyanobacterial grazers. The minimum concentration of neem, bel and tobacco phytoextract in water for 100 % mortality of snails were 0.1, 2.0 and 0.05%, respectively. However, trepellent level was only 0.01% for neem and tobacco phytoextract. Complete mortality of nematode (Dorylamus spp.) required a higher concentration level (2%) even in the most effective tobacco phytoextract. Lower levels of phytoextract (0.1%) were found to stimulate growth and nitrogen fixation of cyanobacteria. Application of these plant biomasses resulted in significant increase in cyanobacterial acetylene-reducing activity (ARA) and rice yield and a significant decrease in snail and nematode population. Augmentation of cyanobacterial acetylene-reducing activity was two to three times higher in comparison to the control in both the years of experimentation. Rice yield also increased between 3.8 and 58.5% over the control, depending on the quantity and nature of plant biomass. Tobacco waste was significantly superior in comparison to neem and bel biomass as carrier of cyanobacterial culture.     

Cyanobacteria and Cyanobacterial Lichens from Inselbergs of the Ivory Coast,Africa

This study focuses on the saxicolous lichens and cyanobacteria of the open, exposed rock surface of inselbergs. Twenty-three species of cyanobacteria and 17 cyanobacterial lichen species (“cyanolichens”) from several inselbergs and other rocky outcrops of three major climatic regions, savanna, transition zone and rain forest, are reported from the Ivory Coast. Inselbergs are isolated and frequently mountains consisting of Precambrian granites or gneisses that abruptly rise from the surrounding plains. Cyanobacteria were found to be the dominating organisms on all rock surfaces. The lichens found mainly belong to the family Peltulaceae and a few were present from the family Lichinaceae. Nine species of the cyanolichens and most of the cyanobacteria are new for the Ivory Coast. A gradient in total species number (cyanolichens and cyanobacteria) occurs from the savanna to the rain forest, with a decrease in species number towards the rain forest. Saxicolous cyanobacterial lichens reached a higher species number in the savanna type ecosystem (11) than on inselbergs in the rain forest (7). The cyanolichens and cyanobacteria found are characteristic for larger, light-exposed rock surfaces and species like P. congregate, P. lingulata, P. tortuosa and P. umbilicata preferentially occur on the granite or sandstone of inselbergs.     

Growth characteristics and toxin production in batch cultures of Anabaena flos-aquae: effects of culture media and duration

The effects of media and culture duration on growth, macromolecular composition and toxicity of an anatoxin- a-producing freshwater cyanobacterium Anabaena flos-aquae (UTEX 2383) were evaluated. The four media A₃M₇, CB, MA and B-12 influenced growth in terms of cell number, chlorophyll-a content and specific growth rate. A₃M₇ medium supported the best growth. The macromolecular composition of cultured cells, viz. total carbohydrate, protein and lipid content varied with media and culture duration reaching maximum concentration at various growth periods. The differences were significant due to interaction of the culture medium and duration. Toxicity of cells grown in different media was compared by Artemia salina bioassay and mouse units. The cells grown in A₃M₇ medium showed highest toxicity and the optimum culture duration was 5 weeks. In terms of both growth characteristics and toxicity the media can be ranked as A₃M₇, MA, CB and B-12 in decreasing order.     

Effect of a constant supply of different nitrogen sources on protein and carbohydrate content and enzyme activities of Anabaena variabilis cells

The effect of the nitrogen source on carbohydrate and protein contents and on several enzymatic activities involved in the carbon and nitrogen metabolism was studied in Anabaena variabilis ATCC 29413 cells grown under a constant supply of either N, NO⁻₃ or NH⁺₄ at different concentrations. An enhancement of protein content accompanied by a parallel decrease of carbohydrates was observed with increasing NO⁻₃ or NH⁺₄ concentrations in the medium. In cultures containing 0.1 m M NO⁻₃ or 0.1 m M NH⁺₄ nitrogenase (EC 1.18.6.1) activity was 74 and 66%, respectively, of that found in N₂-grown cells. This activity was still present with 1 m M NO⁻₃ or 1 m M NH⁺₄ in the medium and even with 10 m M NO⁻₃, but it was completely inhibited by 5 m M NH⁺₄. Ferredoxin-nitrate reductase (EC 1.7.7.2) activity was detected only in NO⁻₃ grown cells and simultaneously with nitrogenase activity. Increasing concentrations of combined nitrogen in the medium, especially NH⁺₄, promoted a concomitant decline of glutamine synthetase (EC 6.3.1.2), NADP⁺-isocitrate dehydrogenase (EC 1.1.1.42), and NAD⁺-malate dehydrogenase (EC 1.1.1.37) activities, suggesting that these enzymes play an important role in the regulation of carbon-nitrogen metabolism in cyanobacteria.     

Evolution of the Inner Light-Harvesting Antenna Protein Family of Cyanobacteria,Algae, and Plants

Two hypotheses account for the evolution of the inner antenna light-harvesting proteins of oxygenic photosynthesis in cyanobacteria, algae, and plants: one in which the CP43 protein of photosytem II gave rise to the extrinsic CP43-like antennas of cyanobacteria (i.e. IsiA and Pcb proteins), as a late development, and the other in which CP43 and CP43-like proteins derive from an ancestral protein. In order to determine which of these hypotheses is most likely, we analyzed the family of antenna proteins by a variety of phylogenetic techniques, using alignments of the six common membrane-spanning helices, constructed using information on the antenna proteins’ three-dimensional structure, and surveyed for evidence of factors that might confound inference of a correct phylogeny. The first hypothesis was strongly supported. As a consequence, we conclude that the ancestral photosynthetic apparatus, with 11 membrane-spanning helices, split at an early stage during evolution to form, on the one hand, the reaction center of photosystem II and, on the other hand, the ancestor of inner antenna proteins, CP43 (PsbC) and CP47 (PsbB). Only much later in evolution did the CP43 lineage give rise to the CP43’ proteins (IsiA and Pcb) of cyanobacteria. [Reviewing Editor: Dr. Patrick Keeling]     

Effects of light (photoperiod,spectral composition) on the population dynamics of Tisbe holothuriae Humes (Copepods,Harpacticoida)

The harpacticoid copepod Tisbe holothuriae Humes was reared for several generations under different photoperiods (white light) and spectral quality (continuous illumination). The main life cycle parameters were measured and demographic variables were determined. Development time was retarded under green wavelengths and at photoperiods different from LD 12:12, especially under continuous white light. Total body length of females and males was shortest under LD 12:12 and longest under constant dark. Photoperiods different from LD 12:12 prolonged the interval between broods of egg sacs. Short photoperiods caused higher abortion rate, while long photoperiods retarded the maturation time of the egg sacs. Red wavelengths stimulated the abortion rate. Photoperiod LD 12:12 and blue wavelengths increased the production of offspring and the life span of females. Highest intrinsic rates of natural increase were estimated under LD 12:12 (rm =0.304) and blue wavelengths (rm = 0.254). These light conditions proved the most favourable for rearing Tisbe holothuriae.     

Epilithic and Cryptoendolithic Cyanobacteria of Clarens Sandstone Cliffs in the Golden Gate Highlands National Park,South Africa

A cryptoendolithic cyanobacterial community is described from Clarens sandstone in a montane ecosystem of the north-eastern Orange Free State, South Africa. The community is dominated by a species of the unicellular cyanobacterial genus Chroococcidiopsis. Chlorophyll_a content of the colonised sandstone ranged between 44.3 and 51.8mg m^?2. The establishment and species composition of an artificially created tintenstrich cyanobacterial community is documented. The possible contribution of cryptoendolithic cyanobacterial communities in the biological formation of hollows and caves in Clarens sandstone cliffs is discussed.     

Effects of aluminium on ATP pools and utilization in the cyanobacterium Anabaena cylindrica: a model for the in vivo toxicity

ATP pools extracted from the cyanobacterium Anabaena cylindrica , grown in the absence or presence of AlCl₃, were measured using the luciferin-luciferase assay. Addition of low concentrations of AlCl₃ (3.6–36 μ M ) increased the ATP pool 20–40% within 24 h, the effect being more marked with time. When using the Tris-EDTA boiling technique for extraction of cellular ATP, the ATP from aluminium-exposed cells appeared more stable during the extraction than the ATP from untreated cells. The higher ATP pools in aluminium-exposed cells were also evident after dark treatment and addition of the phosphorylating inhibitors carbonylcyanide m -chloro-phenylhydrazone (CCCP) and N,N-dicyclohexylcarbodiimide (DCCD). The formation of elevated ATP pools in cells exposed to aluminium was curtailed by high concentrations of cellular phosphate and postincubation at high pH (>8). These results favour the hypothesis that intracellular aluminium binds to ATP by competing with Mg²⁺ and, as a consequence, the stable Al³⁺-ATP complex formed is no longer available for cellular metabolism. The cyanobacterium is assumed to compensate by increasing the total pool of ATP. At high AlCl₃-concentrations, and in particular at low phosphate: aluminium molar ratios (<1), aluminium apparently also interferes with the membranes in A. cylindrica as indicated by inhibited O₂ production, reduced ATP production and cell lysis.     

Biodiversity in extreme aquatic environments: Lakes, ponds and streams of the Ross Sea sector, Antarctica

The Ross Sea Sector (RSS) of Antarcticallies between the lines of longitude 150°E and 150°W and contains diverse landscapes with a variety of lakes, ponds and streams. Neither insects nor crustacean species have been recorded in these ecosystems but most contain planktonic and/or benthic communities that are composed exclusively of microscopic organisms. Microbial brodiversity is low with a small number of species (e.g. filamentous cyanobacteria of the family Oscillatoriaceae) occurring under a broad range of environmental conditions throughout the region. There is no evidence to date of microbial endemism in the RSS; however, there is a need to apply molecular and cellular techniques to compare biodiversity and genetic characteristics with assemblages elsewhere in Antarctica and with comparable communities in the north polar zone. A series of hypotheses are advanced to help guide further work. These derive from the conclusion that environmental extremes plus biogeographical isolation control the biodiversity of RSS communities, and that biological interactions (competition, grazing, predation, parasitism) are weak and play a minor role by comparison with temperate latitude ecosystems.     

Phenotypic and Molecular Biological Characterization of Cyanobacteria from Marble Surfaces of Treated and Untreated Sites of Propylaea (Acropolis,Athens)

Cyanobacteria cause aesthetic damage to marble surfaces and in particular their endolithic mode of life contributes to the breakdown of rock crystalline structures. The aim of this work was to estimate, with both phenotypical and molecular approach, the composition of cyanobacterial communities on the Propylaea marbles of the Acropolis Monuments. The two selected sampling sites were treated and untreated with a commercial biocide in order to estimate its effect on the cyanobacterial diversity. Our study revealed that in both sampling sites were present 13 phenotypes and 10 phylotypes and that the cyanobacterial taxa were considerably lower in the treated site.     

Spectroscopic and Biochemical Analyses of UV Effects on Phycobiliproteins of Anabaena sp. and Nostoc carmium

The effects of UV (280–400 nm) irradiation on phycobiliprotein composition have been studied in two N₂-fixing cyanobacteria, Anabaena sp. and Nostoc carmium, isolated from rice paddy fields in India. Phycobiliproteins were isolated and separated by sucrose density gradient centrifugation. After UV exposure the top fraction mainly contained carotenoids (absorption maximum at 485 nm), which first showed an increase in intensity and absorption and then a gradual decrease with increasing UV exposure in Anabaena sp., whereas, in Nostoc carmium this fraction showed a steady increase over the whole exposure time. The bottom fraction of both organisms mainly contained phycocyanin (absorption peak at 620 nm) which showed a steady decline in intensity, as well as absorption. Fluorescence excitation at 620 nm resulted in an emission at 650 nm which underwent a shift towards shorter wave-lengths with increasing UV-exposure time, indicating a disassembly of the phycobilisomal complex and of impaired energy transfer from accessory pigments to the reaction centers. SDS PAGE analysis of the fractions revealed a loss of high molecular mass linker proteins and low molecular mass (αβ monomers indicating that the phycobiliproteins, which function as accessory pigments for the operation of photosystem II, disassemble during UV irradiation.     

Effect of Fungicides and Insecticides on Growth and Enzyme Activity of Four Cyanobacteria

Cyanobacterial populations introduced into crop fields as biofertilizer become non-target organisms for the pesticides and fungicides applied in the field. Effect of four commonly used pesticides viz. Bagalol, Mancozeb (fungicides), Thiodan and Phorate (insecticides) was studied on growth and different enzymes of four cyanobacterial species viz. Nostoc ellipsosporum, Scytonema simplex, Tolypothrix tenuis, and Westiellopsis prolifica. EC 50 concentration of each pesticide was determined for all cyanobacteria. Bagalol and Thiodan were found to be the most toxic. Both the fungicides and insecticides inhibited the activity of nitrogenase and glutamine synthetase (GS) at EC 50 concentration in all the four species studied. Bagalol incurred maximum inhibition of nitrogenase and GS activity on N. ellipsosporum and S. simplex while Thiodan and Phorate had maximum effect on T. tenuis, and W. prolifica. Mancozeb had lesser effect on all the above enzymes. One catabolic enzyme of carbohydrate metabolism, isocitrate dehydrogenase (ICDH) and one anabolic enzyme isocitrate lyase (ICL), which is related to glyoxylate pathway as well as gluconeogenesis, were also assayed. Cell free extracts of cyanobacteria treated with pesticides for 7 days show a drastic reduction of ICDH activity. ICL activity was induced in the organisms when treated with pesticides.     

植物生长调节剂对转基因鱼腥藻7120生长与外源基因表达的影响

适宜浓度的IBA、6-BA、赤霉酸和氯化胆碱均促进转基因鱼腥藻7120生长,提高其生物量,不影响外源基因表达,但从总体上讲高浓度植物生长调节剂则抑制藻细胞生长,降低外源基因表达水平.这些植物生长调节剂混合施用促进转基因鱼腥藻生长效果不如单一因子好,外源基因表达水平也略有下降.     

Positive and Negative Effects of Habitat-Forming Algae on Survival,Growth and Intra-Specific Competition of Limpets

Understanding the effects of environmental change on the distribution and abundance of strongly interacting organisms, such as intertidal macroalgae and their grazers, needs a thorough knowledge of their underpinning ecological relationships. Control of grazer-plant interactions is bi-directional on northwestern European coasts: grazing by limpets structures populations of macroalgae, while macroalgae provide habitat and food for limpets. Scottish shores dominated by the macroalga Fucus vesiculosus support lower densities and larger sizes of limpets Patella vulgata than shores with less Fucus. These patterns may be due to differences in inter-size-class competitive interactions of limpets among shores with different covers of Fucus. To examine this model, densities of small and large limpets were manipulated in plots with and without Fucus. Amounts of biofilm were measured in each plot. The presence of Fucus increased survival but hindered growth of small (15 mm TL) limpets, which were negatively affected by the presence of large limpets (31 mm TL). In contrast, large limpets were not affected by the presence of Fucus or of small limpets. This suggests the occurrence of asymmetric inter-size-class competition, which was influenced by the presence of macroalgae. Macroalgae and increased densities of limpets did not influence amounts of biofilm. Our findings highlight the role of interactions among organisms in generating ecological responses to environmental change.