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At least 163 records · Page 9Linked to original sources
PubMed2003

Specificity in the settlement -- modifying response of bacterial biofilms towards zoospores of the marine alga Enteromorpha.

Previous studies have shown that the rate of settlement of zoospores of the green alga Enteromorpha is stimulated by mixed microbial biofilms and that the number of zoospores settling is positively correlated with the number of bacteria in the biofilm. In the present study the specificity of this relationship has been investigated. Ninety-nine strains of marine bacteria were isolated from natural biofilms on rocks and the surface of Enteromorpha plants. Isolates were screened by denaturing gradient gel electrophoresis (DGGE) to eliminate replicates and 16S rDNA sequencing identified a total of 37 unique strains. Phylogenetic analysis revealed that the isolated bacterial strains belonged to three groups gamma-Proteobacteria (28 strains), Cytophaga-Flavobacteria-Bacteroid (CFB) group (six strains) and alpha-Proteobacteria (one strain). Two strains were unassigned, showing < 93% sequence similarity with the CFB group. The main genera of gamma-Proteobacteria were Pseudoalteromonas (14 strains), Vibrio (five strains), Shewanella (five strains), Halomonas (three strains) and Pseudomonas (one strain). Spore settlement experiments were conducted on single-species biofilms, developed for different times on glass slides. The effect of correcting spore settlement values for biofilm density was evaluated. Results showed that the effect of bacterial strains on spore settlement was strain- but not taxon-specific and activity varied with the age of the biofilm. However, most of the strains belonging to genera Vibrio and Shewanella showed stimulation. Pseudoalteromonas strains showed a range of effects including settlement-inhibiting, paralysing and lysing activities. Spatial analysis of bacterial density in the presence and absence of spores revealed a range of different types of association between spores and bacteria. Overall, the spatial association between spores and bacteria appears to be independent of the overall quantitative influence of bacterial cells on spore settlement.

Animals↗
PubMed2006

Chronic toxicity of 2,4,2',4'-tetrabromodiphenyl ether on the marine alga Skeletonema costatum and the crustacean Daphnia magna.

Polybrominated diphenyl ethers form a group of highly hydrophobic and persistent chemicals that are detected in various environmental matrices, such as soil, water, sediments, and biota. Although a variety of biological effects have been documented in vertebrates, the effects in invertebrates seem to be largely unknown. The objective of the present study was to determine the toxic effects of 2,4,2',4'-tetrabromodiphenyl ether (BDE 47) on the growth of the marine diatom Skeletonema costatum and on the parthogenetic reproduction and filtering activity of the freshwater crustacean Daphnia magna. The results showed that BDE 47 caused growth inhibition in S. costatum (no-observed-effect concentration [NOEC], 6.6 microg/L; median effect concentration, 70 microg/L; 95% confidence interval, 64-77 microg/L) and depressed the reproductive output of D. magna (NOEC, 14 microg/L). No effects were seen on the filtering rate of D. magna at any of the concentrations tested. Although sublethal toxicity was observed at low-microg/L levels, documented environmental water concentrations are many orders of magnitude lower, thus suggesting that BDE 47 is of minor risk to these organisms through direct water exposure.

Animals↗
PubMed2002

An antioxidant function for DMSP and DMS in marine algae.

The algal osmolyte dimethylsulphoniopropionate (DMSP) and its enzymatic cleavage product dimethylsulphide (DMS) contribute significantly to the global sulphur cycle, yet their physiological functions are uncertain. Here we report results that, together with those in the literature, show that DMSP and its breakdown products (DMS, acrylate, dimethylsulphoxide, and methane sulphinic acid) readily scavenge hydroxyl radicals and other reactive oxygen species, and thus may serve as an antioxidant system, regulated in part by enzymatic cleavage of DMSP. In support of this hypothesis, we found that oxidative stressors, solar ultraviolet radiation, CO(2) limitation, Fe limitation, high Cu(2+) (ref. 9) and H(2)O(2) substantially increased cellular DMSP and/or its lysis to DMS in marine algal cultures. Our results indicate direct links between such stressors and the dynamics of DMSP and DMS in marine phytoplankton, which probably influence the production of DMS and its release to the atmosphere. As oxidation of DMS to sulphuric acid in the atmosphere provides a major source of sulphate aerosols and cloud condensation nuclei, oxidative stressors--including solar radiation and Fe limitation--may be involved in complex ocean atmosphere feedback loops that influence global climate and hydrological cycles.

Antioxidants↗
PubMed2006

Spectroscopy of the peridinin-chlorophyll-a protein: insight into light-harvesting strategy of marine algae.

An important component of the photosynthetic apparatus is a light-harvesting system that captures light energy and transfers it efficiently to the reaction center. Depending on environmental conditions, photosynthetic antennae have adopted various strategies for this function. Peridinin-chlorophyll-a protein (PCP) represents a unique situation because, unlike other antenna systems which have a preponderance of chlorophyll, it has the carotenoid, peridinin, as its major pigment. The key structural feature of peridinin is a conjugated carbonyl group. Owing to the presence of this group, an intramolecular charge-transfer excited state is formed in peridinin which exhibits different excited state spectra and dynamics depending on the polarity of the environment. The charge-transfer state also facilitates energy transfer between peridinin and chlorophyll-a in PCP. This review summarizes results of spectroscopic investigations of PCP in the past few years, emphasizing the specific light-harvesting strategy developed by marine photosynthetic organisms utilizing carbonyl-containing carotenoids in their antenna complexes.

Carotenoids↗
PubMedDate not supplied

Toxins of some marine algae (Pyrrophyta).

The literature data on toxins of neuroparalytic action, produced by pyrrophytic algae and capable of being accumulated by edible mollusks, are presented. The LD50 for mice of saxitoxin, the best known and most strongly acting toxin, is 5-10 microgram/kg. some toxins of dinoflagellates have been isolated in purified form. Their physicochemical properties have been studied and the structural formula of crystalline derivatives of saxitoxin has been established. The major problem of environmental protection is associated with a study of toxic dinoflagellates.

Animals↗
PubMed2000

Biosorption of heavy metals by marine algae.

The ability of four different algae (three brown and one red) that have not been previously studied to adsorb Cr(3+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) ions was investigated. The metal uptake was dependent on the type of biosorbent, with different accumulation affinities towards the tested elements. The HCl-treated biomass decreased the metal biosorptive capacity particularly in the case of Cr(3) adsorption with Laurencia obtusa. The extent of uptake of the different metals with the tested algae was assessed under different conditions such as pH, time of algal residence in solution with the metal, and concentration of algal biomass. The rate of uptake of the different metals was very fast in the first 2 h; thereafter the increase in metal uptake was insignificant. The amount of the metal uptake (5-15 mg range) increased steeply by increasing the weight of the biomass. An exception was L. obtusa, where a parallel increase of the uptake of different metals was observed on increasing the algal mass from 5 to 50 mg.

Biomass↗
PubMed2006

The dodecameric vanadium-dependent haloperoxidase from the marine algae Corallina officinalis: cloning, expression, and refolding of the recombinant enzyme.

The dodecameric vanadium-dependent bromoperoxidase from Corallina officinalis has been cloned and over-expressed in Escherichia coli. However, the enzyme was found to be predominantly in the form of inclusion bodies. This protein presents a challenging target for refolding, both due to the size (768kDa) and quaternary structure (12x64kDa). Successful refolding conditions have been established which result in an increase in the final yield of active bromoperoxidase from 0.5mg to 40mg per litre of culture. The refolded protein has been characterised and compared to the native enzyme and was shown to be stable at temperatures of 80 degrees C, over a pH range 5.5-10 and in organic solvents such as ethanol, acetonitrile, methanol, and acetone. The novel refolding approach reported in this paper opens up the full potential of this versatile enzyme for use in large scale biotransformation studies.

Amino Acid Sequence↗
PubMed1985

Acute toxic effects in mice of an extract from the marine algae Gonyaulax monilata.

Unialgal cultures of Gonyaulax monilata were cultured and harvested. A modified Westphall procedure was used to prepare an extract which did not contain saxitoxin, the gonyautoxins and structurally related toxins. The extract was administered i.p. to young adult, male CD-1 mice and produced: sedation, abdominal constriction, fecal clumping in the perianal area, ataxia, tremors, cyanosis, loss of reflexes, convulsions and death (LD50 = 2.28 mg/kg). Gross and microscopic pathology in the treated mice included: acute active hyperemia of the viscera, multifocal areas of necrosis of the musculature of the intestinal wall and diaphragm and the presence of cytoplasmic vacuoles in the peripheral margins of the acinar portion of the pancreas. Clinical pathology of the mice which survived 24 hr included significant elevation in the levels of serum lactic dehydrogenase, glutamic pyruvic and glutamic oxaloacetic transaminases. Some of these mice also had significantly decreased white blood cell counts. The extract administered orally produced similar signs without the abdominal constriction and convulsions (median lethal oral dose = 6.73 mg/kg). Gross pathology findings included extensive and severe congestion of the abdominal visceral organs. Vehicle control mice were normal. In conclusion, G. monilata, previously reported as nontoxic in homeotherms, yields an extract which contains a water soluble glycosidic substance(s) which is lethal to mice.

Animals↗
PubMedDate not supplied

Prevention of aflatoxin B1-initiated hepatotoxicity in rat by marine algae extracts.

Chemoprevention by extracts of Laurencia obtusa (E1) and Caulerpa prolifera (E2) collected from the Egyptian coast of the Red Sea against aflatoxin B(1) (AFB(1))-initiated hepatotoxicity in female Sprague-Dawley rats has been studied. Animals were fed aflatoxin-contaminated diet (3 mg kg(-1) diet) for 6 days then treated orally with pure aflatoxin B(1) (AFB(1)) (200 microg kg(-1) b.w.) for 4 days either in combination with or before E1 or E2 administration (50 mg kg(-1) b.w.). AFB(1) resulted in a signicant increase in serum alpha fetoprotein, carcinoembryonic antigen, tumor necrosis factor alpha, nitric oxide, interleukin-1alpha, procollagen III and lipid peroxidation level in the liver. It caused a signicant decrease in food intake, body weight, serum leptin, the activities of glutathione peroxidase, superoxide dismutase and DNA and RNA concentrations in the liver. Cotreatment with AFB(1) and E1 or E2 resulted in an obvious improvement in all tested parameters. Noteworthy, E2 was more effective than E1 in the protection against AFB(1)-induced hepatotoxicity.

Aflatoxin B1↗
PubMed2003

In vitro snake venom detoxifying action of some marine algae of Gulf of Mannar, south-east coast of India.

The extract of the brown seaweed Padina boergesenii and the red seaweed Hypnea valentiae was found to detoxify (in vitro) the venom of Naja nigricollis. There was a remarkable reduction in the mortality of albino mice after intraperitoneal (i.p.) administration of reconstituted venom with the extract compared to those challenged with the venom only. The survival of the animals exposed to the venom incubated with the different concentrations of the extract was used as the in vitro detoxification parameter.

Animals↗
PubMed2000

Peridinin as the major biological carotenoid quencher of singlet oxygen in marine algae Gonyaulax polyedra.

Carotenoids in light-harvesting proteins and reaction centers increase the overall efficiency of photosynthesis by transferring absorbed light energy to chlorophylls. Peridinin and beta-carotene were isolated from Gonyaulax polyedra in a one-step purification protocol using the preparative circular chromatography (Chromatotron), performed on silica gel under N(2) atmosphere and n-hexane/acetone 8:2 as mobile phase and characterized by extensive (1)H NMR, infrared, and electrospray ionization mass spectrometry analyses. The quenching of singlet molecular oxygen [O(2) ((1)Delta(g))] was evaluated by NIR-emission assays using singlet oxygen generated by sensitization of either perinaphthenone or methylene blue. The NIR-emission assay showed that peridinin quench as singlet oxygen (k(q) = 9.5 x 10(8) M(-1) s(-1)) 5-fold less efficiently than beta-carotene (52 x 10(8) M(-1) s(-1)). A method, based on the use of high-performance liquid chromatography with UV-VIS detection, was then developed for the sensitive quantification of peridinin (55% of total carotenoids) and beta-carotene (4.1% of total carotenoids). Thus, since peridinin is 10-fold more abundant than beta-carotene, it is expected to be the major protector against the deleterious effects of O(2) ((1)Delta(g)) in Gonyaulax polyedra.

Animals↗
PubMed1991

The toxic action and interactions of copper and cadmium to the marine alga Dunaliella minuta, in both acute and chronic exposure.

The effective concentrations of copper and cadmium which reduced the population growth of Dunaliella minuta by 50% after 96 h of static exposure, were determined to be 7.57 microM Cu and 0.34 microM Cd. Short-term static exposure to both metals indicated that their combined action is antagonistic with respect to growth of this chlorophyte. Additionally, long-term exposure to low levels of Cu or Cd led to the acquisition of tolerance towards Cu and Cd, respectively, and co-tolerance towards Cu.

Cadmium↗