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PubMed1981

[Preliminary investigation of the in vitro inhibitory effect of antibiotics on algae of the genus Prototheca].

We investigated the possible inhibitory action 'in vitro' by antibiotic containing discs against microscopic alga that are potential human pathogens of the genus Prototheca especially P. wickerhamii. The results indicated that inhibitors in vitro included amikacin, colistin, dibecacin, framicetin, gentamycin, kanamycin, lividomycin, neomycin, polymyxin, paromomycin, ribostamycin, sisomycin and tobramycin. We emphasize the interest in the effectiveness at these drugs in a case of human protothecosis.

Anti-Bacterial Agents↗
PubMed1996

Bovine mastitis due to algae of the genus Prototheca.

Protothecosis was described in many animals, with bovine mastitis being the main form. The increasing number of isolations of Prototheca spp. from bovine mastitis cases indicates the need of a detailed evaluation of this problem. Besides this, these algae do not respond to treatment with the antimicrobians most frequently applied, leading to elimination of the affected animals, as the best method to control the disease. In two dairy farms in the State of São Paulo, Brazil, a total of 155 lactating cows and 52 dry cows were examined. Milk samples were aseptically collected from lactating cows with clinical or subclinical mastitis. From dry cows, secretion samples from all quarters were collected. All samples were then taken to microbiological exams. At dairy farm 1, Prototheca spp. was isolated from 14.95% milk samples from lactating cows, (all of them cases of subclinical mastitis), and from 8.06% samples from dry cows. At dairy farm 2, Prototheca spp. was isolated from 5.1% milk samples and there were ten cases of clinical mastitis due to this agent. Although clinical mastitis has been considered the main form of occurrence of this pathology until now, it is important to consider Prototheca spp. as subclinical mastitis pathogen. Prototheca zopfii was the main specie isolated. In this study a high rate of intramammarian infections, as clinical or subclinical mastitis during lactation as well as in dry period, was observed, high lighting the importance of suitable diagnosis, so that control and preventive measures can be implemented to avoid dissemination of the agent.

Animals↗
PubMed1977

Isolation and characterization of disc-shaped phycobilisomes from the red alga Rhodella violacea.

Disc-shaped phycobilisomes were purified from Triton X100 treated cell homogenates of the unicellular marine red alga, Rhodella violacea. Their absorption spectrum had principal maxima at 544 and 568 nm (B-phycoerythrin), 624 nm (C-phycocyanin) and a distinct shoulder at 652 nm (allophycocyanin). Intermolecular energy transfer within the phycobilisomes was clearly demonstrated by fluorescence data. Excited at 546 nm intact phycobilisomes showed a main fluorescence emission maximum at 665 nm, a minor one at 577 nm and a shoulder at 730 nm. Dissociated phycobilisomes revealed a composition of 58% B-phycoerythrin, 25% C-phycocyanin and 17% allophycocyanin under the cultural conditions used. Analytical methods resolved no other components than phycobiliproteins. In addition to the defined C-phycocyanin and two isoproteins of B-phycoerythrin a stable heterogeneous aggregate of B-phycoerythrin/C-phycocyanin was separated in considerable amounts. In the electron microscope negatively stained phycobilisomes appeared as elliptical aggregates having dimensions slightly above the values found in ultrathin sections and a detailed subunit structure. All observations and data suggest a new rhodophytan phycobilisome type in Rhodella violacea.

Cell Fractionation↗
PubMed1975

The effect of pyruvate on nitrogenase activity in the blue-green alga Anabaena cylindrica.

Exogenous pyruvate added to cultures of the blue-green alga, Anabaena cylindrica stimulated nitrogenase activity (measured by acetylene reduction) only in the dark under low pO2 (0.05 atmospheres). Under aerobic conditions or in the light, stimulation was absent and replaced by an inhibition of activity above 5 mM added pyruvate. The curve of nitrogenase activity versus oxygen concentration had a similar maximal value of ethylene production with, or without added pyruvate, but in the presence of pyruvate this maximum occurred at 0.05 atmospheres O2, whilst in the absence of pyruvate the maximum occurred at 0.10 atmospheres O2. Malate, citrate, alpha-ketoglutarate, glucose and fructose were tested also, but none gave a similar effect to pyruvate. Addition of 14C-pyruvate and autoradiography indicated that exogenous pyruvate is metabolized through the interrupted Krebs cycle. These results are explained in terms of the activity of pyruvate: ferredoxin oxidoreductase and the ATP-induced oxygen sensitivity of nitrogenase.

Acetylene↗
PubMed1975

Effect of vanadium on growth, chlorophyll formation and iron metabolism in unicellular green algae.

In the presence of vanadium, growth of Scenedesmus obliquus and Chlorella pyrenoidosa was increased five to sixfold as determined by dry weight, when cultured under autotrophic conditions for 7 days. The stimulation by vanadium decreased with increasing stability towards hydrolysis of the iron(III)-compounds added. Pentavalent vanadium (20 mug V/1 as NH4VO3) was able to overcome completely a limited iron-deficiency in the algae following growth in presence of 1.8 - 10(-5) m ferric chloride. Vanadium did not alter the iron uptake into the algal cells. 90% of offered 48V was taken up by Scenedesmus obliquus during 5 days of growth, and 21% thereof were found in the chloroplast fraction. In presence of vanadium, the chlorophyll formation was stimulated in Scenedesmus obliquus. This stimulation by vanadium was found to be light-dependent but occurred to a certain extent in the dark also. The main porphyrin of the yellow mutant 211-11h/20 of Chlorella vulgaris was identified as protoporphyrin-IX. The formation of this compound was stimulated by vanadium within 10 days up to 83%. The role of vanadium in the biosynthesis of chlorophylls is discussed.

Chlorella↗
PubMed1976

ATP pools and transientss in the blue-green alga, Anabaena cylindrica.

Anabaena cylindrica grown in steady state continuous culture has an extractable ATP pool, measured on the basis of the luciferin-luciferase assay of 165 +/- 35 nmoles ATP mg chla-1. This pool is maintained by a dynamic balance between the rate of ATP synthesis and the rate of ATP utilization. Phosphorylating mechanisms which can maitain the pool in the short term are total photophosphorylation, cyclic photophosphorylation and oxidative phosphorylation. The alga can maintain its ATP pool by switching rapidly from one of these phosphorylating mechanisms to another depending on the environmental conditions. At each switch-over there is a transient drop in the ATP pool for a few seconds. On switching to conditions where only substrate level phosphorylation operates, the ATP pool falls immediately, but takes several hours to recover. The apparent rates of ATP synthesis by total photophosphorylation and by cyclic photophosphorylation are both much higher (210 +/- 30 and 250 +/- 13 mumoles ATP mg chla-1 h-1 respectively) than the apparent rate of ATP synthesis by oxidative phosphorylation (22 +/- 3 mumoles ATP mg chla-1 h-1). In long term experiments the ATP pool is maintained when total photophosphorylation is operating. It cannot be maintained in the long term by cyclic photophosphorylation alone in the absence of photosystem II activity in endogenous carbon compounds, or by oxidative phosphorylation in the absence of endogenous carbon compounds. Measurements of ATP, ADP and AMP show that the total pool of adenylates is similar in the light and in the dark in the short term. There is only limited production of ATP under dark anaerobic conditions when glycolysis and substrate phosphorylation can operate which suggests that these processes are of limited significance in providing ATP in Anabaena cylindrica.

Adenosine Triphosphate↗
PubMed1981

Deformation of isolated rat hepatocytes by a peptide hepatotoxin from the blue-green alga microcystis aeruginosa.

The effect of the peptide hepatotoxin from the bloom-forming blue-green alga Microcystis aeruginosa was investigated on isolated rat hepatocytes. When toxin was added to hepatocyte suspensions it produced deformation of the cells, as shown by scanning electron microscopy. This was apparent within 5 min of addition of toxin to the cells and the response was dose dependent: 30 ng of toxin was sufficient to cause deformation in 58 +/- 9% of 1.4 x 10(6) hepatocytes/ml of incubation. The deformation did not lead to cell death as measured by Trypan blue uptake within 120 min. Deoxycholate, cholate bromosulphophthalein, and rifampicin were found to prevent the deformation of hepatocytes by Microcystis aeruginosa toxin in a dose dependent manner, analogous to the effect of these agents on the response of hepatocytes to added phalloidin. This suggests that Microcystis aeruginosa toxin is transported into hepatocytes in the same way as phalloidin; namely sharing a transport system for bile acids on the hepatocyte plasma membrane.

Animals↗
PubMed1991

Free radical production by the red tide alga, Chattonella antiqua.

The red tide alga, Chattonella antiqua, was found to show a strong chemiluminescence, using luminol as the reagent, when exposed to ultraviolet irradiation. This luminescence was completely inhibited by ascorbate or catalase, suggesting that hydrogen peroxide was generated by the plankton. Red tide cells exposed to fish gill mucus from young yellowtail resulted in the release of a large number of mucocysts and a weak luminosity, and showed a strong reduction of cytochrome c in the medium. Therefore, the discharge of mucocysts from the red tide, induced by the presence of gill mucus, may be accompanied by the release of active oxygen species. The active oxygen may be involved in depolymerization of mucus glycoproteins from the gill lamellae.

Animals↗
PubMed1980

Toxicity and bioaccumulation of cadmium in the colonial green alga Scenedesmus obliquus.

A laboratory investigation was conducted to study the extent and efficiency of cadmium bioaccumulation in Scenedesmus obliquus by subjecting this alga to varied sublethal Cd concentrations. The influence of cell population age on Cd bioaccumulation was also studied. Under the experimental conditions employed, growth was not significantly affected by Cd concentrations ranging from 0.01 ppm to 1.00 ppm. At concentrations above 1.00 ppm, however, growth was inhibited markedly. Increases in external Cd concentration caused an increase in total bioaccumulation over the entire range of concentrations, which did not significantly affect growth. Efficiency of Cd bioaccumulation was also concentration dependent, but maximum accumulation efficiency occurred in a medium with a Cd concentration lower than that medium in which maximum total bioaccumulation occurred. Age of the cell population influenced the extent of Cd bioaccumulation. Rapidly growing, young cultures accumulated less Cd than older cultures approaching stationary growth phase.

Cadmium↗
PubMed1993

The growth response of the green alga Chlorella vulgaris to combined divalent cation exposure.

Using the growth response of the green alga Chlorella vulgaris as a model system, the effects of combinations of the environmentally active cations Cd, Co, and Cu were evaluated. The 96-h static EC50 for these cations to C. vulgaris were, respectively, 0.89 microM, 9.0 microM, and 2.8 microM, yielding a toxicity series such that Cd > Cu > Co. The cation combinations of Cd + Cu, and Cu + Co acted synergistically, while Cd + Co, and the tri-metallic combination Cd + Cu + Co resulted in antagonistic interactions. Examination of these toxic combinations at 24, 48, 72, and 96 h indicate that the cellular response is not a uniform one. Failure of energy dispersive X-ray spectrophotometric analysis to demonstrate any intracellular incorporation of these cations (except for a weak cytoplasmic Cu peak at the 8.0 KEV position) suggests that the toxic actions of these cations at EC50 concentrations are exerted at the level of the plasma membrane.

Cadmium↗
PubMed1989

Fatty acid composition of eleven algae from coastal zones of Qatar.

The fatty acid composition of eleven species of algae belonging to Rhodophyceae, collected from the coastal zones of Qatar, are reported. The major fatty acids identified were palmitic (16:0), myristic (14:0), oleic (18:1), eicosadienoic (20:2), linoleic (18:2), stearic (18:0) and hexadecaenoic acid (16:1). The fatty acids were characterized by the relatively high abundance of polyunsaturated acids, while the C18 unsaturated acids were appreciably more abundant than the C20 unsaturated acids.

Eukaryota↗
PubMed1989

Doppler velocimetry measurements of phototactic response in flagellated algae.

A periodic shading mechanism (about 0.5 s period) is believed to be used by flagellated algae to detect light direction. Time changes in the orientation of a population of Haematococcus pluvialis under positive photoaxis conditions (cell samples were stimulated alternatively by two diametrically opposed beams of actinic light), have been investigated by analysing the Doppler shifts of laser light scattered by the cells by means of heterodyne detection techniques. This technique allows us to measure the mean value of the component of the cells' swimming velocities along the light stimulus axis. Preliminary data indicate that the time taken by a cell population to change orientation is about 1 s.

Cell Movement↗
PubMed1991

Metal pollution and its impact on algae in flowing waters in India.

Metal pollution in the river Godavari in India, due to discharges of liquid wastes from a paper mill, has been studied for a period of two years. At the discharge point and 1 km from the point of discharge, iron, manganese, and zinc were recorded in high concentrations, whereas cadmium and chromium were observed in low concentrations. No metal was in detectable concentration in water before the river receives the effluents. A considerable drop in pH values and an appreciable increase in organic matter, hardness, and calcium levels were noticed after entry of wastes. Diatoms were more diversified in fresh water, whereas cyanobacteria were more prevalent both qualitatively and quantitatively at the polluted stations. Mathematical equations involving heavy metals and physicochemical factors were drawn for better understanding of the distribution of algae.

Eukaryota↗
PubMed1976

Mutation to resistance for virus N-1 in the blue-green alga Nostoc muscorum.

The spontaneous and nitrosoguanidine induced N-1 virus resistant mutants of the blue-green alga Nostoc muscorum were isolated with the average mutation frequency of 3.55 X 10(-5) and 6.08 X 10(-4) respectively. Of the surviving colonies 8 per cent became virus sensitive,whereas out of the remaining 92 per cent 9.3 per cent showed lysogenic behaviour and 13.3 per cent showed poor or no nitrogen fixing ability. Mutation to virus-resistance was independent of the presence of the virus.Spontaneous host range mutants of virus were not found in repeated experiments.

Adsorption↗
PubMed1975

Effects of the insecticide Zectran (Mexacarbate) on several algae.

Field samples of freshwater algae were examined to determine the effect of the insecticide Zectran on photosynthesis rate. Concentrations of Zectran between 10 and 10(3) parts per billion (ppb) affected neither O2 production nor NaH14CO3 uptake in any of the seven genera tested. However, Zectran at a concentration of 10(4) ppb after 1 hour effected a reduction in photosynthesis of Chroococcus, Oedogonium and in a mixed sample composed of Zygnema,Mougeotia and Spirogyra. Mougeotia, Spirogyra and Schizogonium were not affected by exposure to 10(4) ppb Zectran after 1 hour, but O2 production was significantly reduced after 24 hours of exposure to this same concentration.

Bicarbonates↗