Photoreactivation of UV-irradiated blue-green algae and algal virus LPP-1

Ultraviolet (UV) sensitivity and photoreactivation of blue-green algae Cylindrospermum sp., Plectonema boryanum, spores of Fischerella muscicola and algal virus (cyanophage) LPP-1 were studied. The survival value after UV irradiation of filaments of Cylindrospermum sp. and Virus LPP-1 showed exponential trend and these were comparatively sensitive towards UV than F. muscicola and P. boryanum. Photoreactivation of UV-induced damage occurred in black, blue, green, yellow, red and white light in Cylindrospermum sp., however only black, blue and white light were capable of photorepair of UV-induced damage in P. boryanum, spores of F. muscicola and virus LPP-1 in infected host alga. Pre-exposure to yellow and black light did not show photoprotection. The non-heterocystous and nitrogen fixation-less mutants of Cylindrospermum sp. were not induced by UV and their spontaneous mutation frequency was not affected after photoreactivation. The short trichome mutants of P.boryanum were more resistant towards UV.The occurrence of photoreactivation of UV-induced killing in wide range of light in Cylindrospermum sp. is the first report in organisms.     

Effects of temperature pre-treatment,desiccation and aging on the viability of spores of halophilic blue-green algae

The effects of temperature, desiccation and aging on the viability of spores of Sambhar salt lake blue-green algae, Anabaena fertilissima and Anabaenopsis arnoldii, were studied. Spores of A. arnoldii were found to be more susceptible to temperature variation, desiccation and storage than spores of A. fertilissima. Pre-treatment of spores with higher temperatures, 37° and 47°C, stimulated germination in A. fertilissima. In a sporulated filament, spores which developed first were generally bigger and more resistant to adverse environmental conditions than spores formed later. The differential loss of viability in spores of a filament may be due to certain intrinsic differences in the physiological/ biochemical properties of the spores.     

EFFECT OF LYSOZYME (MURAMIDASE) ON MARINE AND FRESHWATER BLUE-GREEN ALGAE1

Marine blue-green algae, Lyngbya Lagerheimii, Microcoleus chthonoplastes, Plectonema terebrans, Agmenellum quadruplicatum, and freshwater blue-green algae, Anacystis nidulans, Anabaena variabilis, Nostoc muscorura, and Oscillatoria sp. treated with lysozyme (muramidase) formed spheroplasts but not protoplasts. The time needed for spheroplast induction varied with the species. Approximate internal osmotic pressures of the blue-green algae were determined. Marine algae generally had a higher osmotic pressure than freshwater algae.     

Nitrogen fixation (acetylene reduction) associated with communities of heterocystous and non-heterocystous blue-green algae in mangrove forests of Sinai

Summary High rates of nitrogen fixation (acetylene reduction) are associated with communities of heterocystous and non-heterocystous blue-green algae, which are widespread and abundant in the coastal mangrove forests of the Sinai Peninsula.Heterocystous forms, particularly representatives of the Rivulariaceae, grow in aerobic environments, where nitrogenase activity may be limited by the availability of nutrients such as Fe and PO₄–P. Desiccated communities of Scytonema sp. reduce acetylene within ten minutes of wetting by tidal sea water. Communities dominated by the non-heterocystous Hydrocoleus sp., Hyella balani, Lyngbya aestuarii, Phormidium sp. and Schizothrix sp., occur in close contact with anaerobic sediments and reduce acetylene in the dark as well as in the light.Nitrogen fixation in all these communities is light dependant and may be supplemented by an alternative source of reductant in the dark. The indications are that nitrogen fixation by these communities of blue-green algae, makes a significant contribution to the overall nitrogen input of the mangrove ecosystem.     

INHIBITION OF PHOTOSYNTHESIS IN ALGAE BY DIMETHYL SULFOXIDE1

Photosynthetic oxygen evolution and ¹⁴CO₂ fixation by 3 blue-green algae, Anabaena flos-aquae, Oscillatoria sp., and Anacystis nidulans, and 1 green alga, Chlorella pyrenoidosa, were: inhibited by dimethyl sulfoxide at concentrations above 1%.     

A greenhouse study on the effect of inoculation of N-fixing blue-green algae in an alluvial soil treated with P and Mo on the yield of rice and changes in the N-content of soil

Summary The efficiency of the inoculation of three cultures of N-fixing blue-green algaeviz. (i)Aulosira fertilissima (A₁), (ii)Nostoc muscorum (A₂) and (iii) their mixture (A₃) in increasing the grain and straw yield of rice, nitrogen uptake in grain and nitrogen content in soil was studied in a green house experiment with an alluvial soil in presence or absence of urea nitrogen application. Inoculation significantly increased the grain and straw yield of rice and nitrogen uptake in grain, but the efficiency of inoculation gradually decreased with the increase in the levels of urea nitrogen application, the extent of decrease varying with the algal cultures inoculated. The nitrogen content in the soils after the crop harvest recorded a significant increase due to inoculation but after air drying the soil a marker decrease of the same was observed, which indicated that most of the nitrogen added to the soil by blue-green algae through fixation did not persist after air drying the soil.     

Algicidal effect of 2,4-dichlorophenoxy acetic acid on blue-green alga Cylindrospermum sp.

The effect of the herbicide 2,4-Dichlorophenoxy acetic acid generally used in agriculture was studied on the nitrogen fixing blue-green alga Cylindrospermum sp. The alga could tolerate up to 150 μg per ml in liquid culture and 100 μg per ml on agar plates without any inhibitory effect on growth and survival. The maximum tolerance was up to 800 μg per ml and higher concentrations were lethal.     

EPIFLUORESCENCE MICROSCOPY FOR THE STUDY OF NITROGEN FIXING BLUE-GREEN ALGAE ASSOCIATED WITH FUNARIA HYGROMETRICA (BRYOPHYTA)

Funaria hygrometrica Hedw. gametophytes collected in a clearfelled and slash-burned eucalypt forest in southern Tasmania were removed from core samples yielding high rates of nitrogen-fixing activity (acetylene reduction) and were examined with epifluorescence optics to determine the microorganism(s) responsible for nitrogen-fixing activity and their location on the moss gametophytes. This technique revealed heterocystous blue-green algae (Nostoc sp. and Anabaena sp.) as epiphytes on stem and leaf surfaces and within the rhizosphere. Heterocysts and akinetes were observed and could be distinguished from vegetative cells by morphology and a decrease in relative fluorescence in the case of heterocysts. Epifluorescence microscopy is a rapid and reliable method for detecting the epiphytic blue-green algae associated with Funaria. Other examples of nitrogen-fixing organisms associated with bryophytes are discussed in relation to the present study.     

Fine control of citrate synthase activity in blue-green algae

Summary The citrate synthases of four blue-green algae, two unicellular (Aphanocapsa spp.) and two filamentous (Nostoc sp., Phormidium sp.) were inhibited by -ketoglutarate but not by NADH. This control of citrate synthase activity reflects the lack of -ketoglutarate dehydrogenase in blue-green algae and the strictly biosynthetic role played by the glutamate branch of the tricarboxylic acid cycle. The citrate synthases were also inhibited by ATP and the enzyme of one of the unicellular organisms was also sensitive to inhibition by NADPH. These effectors may function in regulating the flow of fixed carbon into lipids rather than the glutamate family of amino acids.Contribution No. 1649 from the University of Miami, Rosenstiel School of Marine and Atmospheric Science, 10 Rickenbacker Causeway, Miami, Florida 33149, U.S.A.     

Applied microalgae photosynthesis: Discharge mechanisms in highly illuminated cells

Based on the hypothesis that discharge mechanisms are induced in highly illuminated thylakoid, we analyze an applied model, which overcomes the damage induced by outdoor solar radiation, partially shaded, air-bubbled, or stirred blue-green algae cultures. The blue-green alga, Oscillatoria sp., exhibits a maximum growth rate at a radiation intensity of 50 J/m²sec. The introduction of 0.1 sec dark periods shifts this peak up to 75 J/m²sec. The radiationless nature of the discharge mechanisms is discussed in accord with the low growth rates of both the experimental and control cultures at 40°C.     

Algal nitrogen fixation on the lava field of Heimaey,Iceland

Summary Nitrogen fixation (C₂H₂ reduction) by blue-green algae occurring on the juvenile lava field of Heimaey, Iceland was examined both in the laboratory (potential at 20° C and 39° C) and in the field, three and a half years after the volcanic eruption.Already at this early stage of colonization representatives of unicellular and filamentous heterocystous and non-heterocystous blue-green algae were commonly observed. The predominating algae were Nostoc sp. (20° C) and Schizothrix sp. — Microcoleus chthonoplastes, (39° C), the former often in association with the protonemata-rhizoids of moss plants.The potential for nitrogen fixation was recorded at an average rate of 109.2 (20° C) and 138.1 (39° C) ng N g^-1 h^-1 in soil collected from localities randomly distributed over the lava field.Tests for nitrogen fixation performed in situ revealed significant fixation activities in all the eleven localities subject to examination. The activities ranged from 2.8 to 63.4 (mean 21.5) ng N g^-1 h^-1 and 1.9 to 17.7 (mean 7.9) ng N cm^-2 h^-1.All the nitrogen fixation data noted imply that blue-green algae contribute a substantial part of the nitrogen input to the lava. Further, it was found that material incubated under micro-aerophilic conditions exhibited considerably enhanced nitrogenase activity.The role of nitrogen-fixing blue-green algae in general and Nostoc muscorum in particular in being suitable as pioneering organisms preparing the bare lava for ingress of other plants is also discussed.     

The colonial rock-forming microfossils of the Bohemian Upper Proterozoic (Czechoslovakia), “Bohemipora Pragensis’ n.g., n.sp.

Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe). They resemble those described by Cayeux (1894) from the Upper Proterozoic (Brioverian) of Bretagne (France). It is shown, unlike the views of Cayeux and his followers (Deflandre, 1955, and Graindor 1957), that the observed structures did not belong to individuals but to colonies of filamentous prokaryotic organisms, most probably blue-green algae (Cyanophyta). These produced specific crystal-like mineral aggregation round each filament. Scanning microscope examination has revealed that the individual facets of these mineral crystals were perforated by the openings through which the thread-like bodies of these primitive organisms protruded. It is shown that these microorganisms were attached to the cells of other, bigger microorganisms and enveloped them. Some of these substrate organisms might have been eukaryotic algae. The thecae gradually accumulated around the cells of these carrier organisms and after death the colonies disintegrated to constitute the main component of the sediment. The microfossils described are just a major component of a complicated fossil assemblage comprising coccoid and filamentous blue-green algae and bacteria. There are indications that several eukaryotic species might also have been present.The following new taxa are described:Thecophytales, new order,Cayeuxidae (Graindor) family emend.,Bohemipora n. gen.,B. pragensis, n. sp.     

Nitrogenase Activity in Relation to Intracellular Organisms in Sphagnum Mosses

Electron microscopic studies of Sphagnum lindbergii (Schimp.) and S. riparium (Ångstr.) have revealed the presence of intracellular organisms such as blue-green algae, green algae, bacteria and fungi. Nitrogenase activities of these Sphagnum mosses were found to be related mainly to the presence of intracellular Nostoc filaments. The appearance of nitrogen-fixing blue-green algae within bryophytes is thus not restricted to liverworts. The association is likely to be of ecological importance as it seems to occur in very acid habitats generally lacking blue-green algae. Possible interrelations between the moss, the blue-green algae and different types of bacteria are discussed.     

Nitrogen fixation by the unicellular blue-green alga Aphanothece

Summary Frequent growth of unicellular blue-green alga Aphanothece sp. was observed in medium free of combined nitrogen. Its generation time was 12 h and more than 2 mg of nitrogen was fixed in 25 days. Its growth and nitrogen fixation were comparable to other heterocystous algae.     

A light and electron microscopic study of the blue-green algae living either in the coralloid roots of « Macrozamia communis » or isolated in culture

Abstract

The present work is a study of the blue-green algae living in the coralloid roots of Macrozamia communis and isolated from Macrozamia communis in culture.

The light and electron microscopic study pointed out the distribution of these microorganisms in the cortical area of coralloids and did not reveal any cells invaded by bacteria. On the basis of their aspect the blue-green algae living either in the coralloid roots or in culture were classified as belonging to the genus Nosloc, with some features of Nosloc commune.

Inside the coralloids the cells of the blue-green algae were surrounded by abundant mucilage and contain granulations. In culture the blue-green algae were on the contrary very poor in mucilage and rich in polyphosphate granules. Numerous phycobilosomes were ranged along the outside of the thylakoid membranes in alternate arrangement to the granules of the neighbouring lamellae.     

Diet,food preference,and algal availability for fishes and crabs on intertidal reef communities in southern California

Synopsis Herbivory by wide-ranging fishes is common over tropical reefs, but rare in temperate latitudes where the effects of herbivorous fishes are thought to be minimal. Along the west coast of North America, herbivory by fishes on nearshore reefs is largely restricted to a few members of the Kyphosidae, distributed south of Pt. Conception. This paper presents information on natural diets and results from feeding choice experiments for two abundant kyphosids from intertidal habitats in San Diego, California —Girella nigricans andHermosilla azurea, and similar data for the lined shore crab,Pachygrapsus crassipes, which also forages over intertidal reefs. These results are compared with the availability of algae in intertidal habitats measured during summer and winter, on both disturbed and undisturbed habitats. The diets of juveniles ofG. nigricans andH. azurea collected from nearshore habitats were dominated by animal prey (mainly amphipods), but adults of these fishes, andP. crassipes, consumed algae nearly exclusively, with 26, 10, and 14 taxa of algae identified fromG. nigricans, H. azurea, andP. crassipes, respectively. Algae with sheet-like morphologies (e.g.Ulva sp.,Enteromorpha sp., members of the Delesseriaceae) were the principal algae in the diets of the fishes, and calcareous algae (e.g.Corallina sp.,Lithothrix aspergillum) and sheet-like algae (Enteromorpha sp.) comprised the greatest identifiable portion of the shore crab's diet. Feeding choice experiments indicated that the fishes preferred filamentous algae (e.g.Centroceras clavulatum, Polysiphonia sp.,Chondria californica) and sheet-like algae (e.g.Enteromorpha sp.,Ulva sp.,Cryptopleura crispa) over other algal morphologies, whereas the shore crab chose jointed calcareous algae (e.g.Lithothrix aspergillum, Corallina vancouveriensis, Jania sp.) most frequently. The diets and preferences for algae by the fishes were generally most similar to the assemblage of algae available in early successional (disturbed) habitats during summer when sheet-like and filamentous algae are abundant. The shore crab exhibited the opposite trend with a diet more similar to late successional (undisturbed) habitats.     

The effects of initial population density on the competition for limiting nutrients in two freshwater algae

Eighteen long-term competition experiments were performed on two freshwater algae, a blue-green alga, Anabaena flos-aquae, and a diatom, Cyclotella sp., under controlled light and temperature conditions and various nutrient limitations. As predicted, Anabaena displaced Cyclotella when nitrate was in short supply to both species, whereas Cyclotella became dominant when both species were phosphate-limited. The two species stably coexisted when phosphate and silicate were limited. Anabaena either displaced or coexisted with Cyclotella when nitrate and phosphate or nitrate, phosphate and silicate were limited, depending on their initial density ratios. This study revealed strong effects of initial population densities on the outcomes of algal competition for limiting nutrients.     

SELECTIVE INHIBITION OF BLUE-GREEN ALGAL GROWTH BY ETHIONINE AND OTHER AMINO ACID ANALOG1,2

Some metabolic analogs, including azaguanine, azathymine, azauracil, caffeine, 4-azaleucine, dl -ethionine, and dl -p-fluorophenylanlanine, were examined for their ability to repress the multiplication of algae from natural aquatic sources grown in defined or semidefined media. dl -ethionine, dl -p-fluorophenylalanine, and 4-azaleucine, in that order, inhibited the multiplication of blue-green but not other algal groups. The purine and pyrimidine analogs were not inhibitory. In chemically defined axenic media, dl -ethionine was about 100 times more inhibitory to the blue-green algae Synechococcus cedrorum and Anabaena cylindrica than to the eucaryotic algae Ochromonas danica and Euglena gracilis. The ciliate Tetrahymena pyriformis was at least 100-fold more resistant to ethionine than the algae. The unusual sensitivity of blue-green algae to ethionine and other amino acid analogs represents an exceptional phylelic character and may be useful in the control of these algae when they become a nuisance. Amino acid analogs such as ethionine may also serve to remove blue-green algae from cultures one may desire to render axenic.     

INTERACTION OF PLECTONEMA BORYANUM (CYANOPHYCEAE) AND THE LPP-CYANOPHAGES IN CONTINUOUS CULTURE1

Continuous culture techniques are used to study long-term population interactions between Plectonema boryanum Gomont, a filamentous bluegreen alga, and the LPP-viruses which infect it. After LPP-I (virulent cyanophage) infection of sensitive algae, 3 oscillations occur in cell density with concomitant oscillations in virus titer before final stabilization of both algal and viral concentrations. After LPP-ID and LPP-2 (temperate viruses) infection, oscillation in cell density occurred with burst of virus particles. Resistant algae always repopulated the chemostat; lysogeny was not established. The interaction between Plectonema that was resistant to virus infection and the 3 LPP-cyanophages resulted in rapid elimination of the viruses from the chemostat in the effluent. When lysogenic P. boryanum was tested, a law population of virus was present in the chemostat throughout the incubation period indicative of spontancous induction. Clones of lysogenic algae were isolated.