Effect of crude sulphated polysaccharide from brown algae against acetaminophen-induced toxicity in rats

This study was conducted to examine the protective role of crude polysaccharide from brown seaweed Sargassum polycystum against acetaminophen-induced abnormality in blood glucose, serum albumin/globulin ratio, and liver glycogen, lactate, and pyruvate. Liver and renal tissue histology was performed to confirm the efficacy of Sargassum polysaccharide. A toxic dose of acetaminophen (800 mg/kg body weight intraperitoneally) induced severe abnormality in all basic parameters with apparent toxicity in liver (enlargement of hepatocytes, loss of cytoplasmic content with disruption in the hepatic plates and sinusoidal dilation) and renal tissue (glomerular damage with congestion of tubules). The isolated liver cells were stained with acridine orange and examined under fluorescence microscope, which revealed that the acetaminophen induced significant damage. In contrast, the rats pretreated with Sargassum polysaccharide (200 mg/kg body weight) daily for 3 weeks did not show liver and renal tissue with these severe aberrations induced by acetaminophen. Histology results were also consistent with analyzed basic biochemical parameters, which confirmed the effectiveness of the crude polysaccharide against acetaminophen-induced abnormality in rats.     

Fucoidan a sulfated polysaccharide from brown algae is a potent modulator of connective tissue proteolysis

Fucoidans are sulfated fucosylated polymers from brown algae cell wall that exhibit some heparin/heparan sulfate properties. We previously demonstrated that these polysaccharides were able in vitro to stimulate dermal fibroblast proliferation and extracellular matrix deposition. Here, we investigated the action of a 16kDa fucoidan fraction on parameters involved in connective tissue breakdown. This fucoidan is able to inhibit gelatinase A secretion and stromelysin 1 induction by interleukin-1beta on dermal fibroblasts in culture. Furthermore, we observed that fucoidan increases the rate of association of MMPs with their specific inhibitors namely TIMPs. Using tissue sections of human skin in ex vivo experiments, we evidenced that this polysaccharide was able to minimize human leukocyte elastase activity resulting in the protection of human skin elastic fiber network against the enzymatic proteolysis due to this serine proteinase. These results suggested that fucoidan could be used for treating some inflammatory pathologies in which uncontrolled extracellular matrix degradation takes place.     

Immunomodulatory activity of brown algae Turbinaria ornata derived sulfated polysaccharide on LPS induced systemic inflammation

BackgroundInflammation and oxidative stress are common pathologies in a wide range of chronic diseases. Polysaccharides are known to exhibit antioxidant and anti-inflammatory potential and are suggested to possess immunomodulatory potential.PurposeHerein, the immunomodulatory activity of a sulfated polysaccharide (PS) separated from a brown marine algae Turbinaria ornata is studied in LPS instigated systemic inflammation in experimental rats.Study design and methodsMale SD rats are pretreated with different doses of PS (2.5, 5, 10 mg/kg bw) for a week followed by inducing systemic inflammation using LPS (10 mg/kg i.p.). Blood withdrawn after 8 h of LPS injection is subjected to hematological analysis (WBC, HCT, and PLT). After 24 h of LPS induction, cardiac tissue was isolated and subjected to biochemical, molecular, and histopathological analysis. Effect of PS pre-treatment (2.5, 5, 10 mg/kg bw) was checked by assessing serum parameters (AST, CK-MB, and γGT), antioxidant markers (LPO, GSH, SOD, Grx) and inflammatory markers (IL1β, IL6, IL10, NFκB), followed by analyzing the iNOS, PI3k and Akt to identify the probable mode of action.ResultsElevated levels of AST, CK-MB, and γGT in serum were significantly reduced on PS pretreatment. LPS significantly raised the LPO and Grx levels in heart tissue whereas, PS pre-treatment significantly reduced LPO and Grx levels. GSH and SOD levels were reduced upon LPS induction and were brought to near normal by HD of PS. PS also reduced the mRNA levels of IL6, Trx, and increased IL10 levels in the heart tissue substantiating its anti-inflammatory and antioxidant potency. Further, IL1β, NFκB, iNOS, and pPI3k/pAkt expressions were significantly modulated by PS in the cardiac tissue substantiating the immunomodulatory effect. A trend of improvement in the inflammatory pathology was also observed in the heart tissue compared to LPS control, as confirmed by histopathology analysis.ConclusionAltogether, this study concludes the immunomodulatory potential of PS from the marine macroalgae Turbinaria ornata significantly and prevents LPS induced systemic inflammation in the cardiac tissue presumably influenced by the glucopyranose and fucopyranose subunits in the polysaccharide.     

Host-virus interactions in marine brown algae

Ectocarpus-like marine brown algae are frequently parasitized by polyhedric DNA viruses. Infected hosts have been studied in unialgal and axenic cultures, and the present state of knowledge is summarized in regard to stage-specific virus expression, discharge and survival time of virus particles, infection mechanism, association with host's nuclear genome, passage of the virus genome through mitosis and meiosis of the host, suppression of symptoms and spontaneous recovery of infected plants, host specificity and intergeneric transmission, vitality of infected plants, pandemic occurrence of virus infections, molecular data on Ectocarpus and Feldmannia viruses, and algal DNA-viruses as potential vectors for gene transfer. A scheme for the nomenclature of brown algal viruses is proposed.     

Cytoskeleton and morphogenesis in brown algae

BACKGROUND: Morphogenesis on a cellular level includes processes in which cytoskeleton and cell wall expansion are strongly involved. In brown algal zygotes, microtubules (MTs) and actin filaments (AFs) participate in polarity axis fixation, cell division and tip growth. Brown algal vegetative cells lack a cortical MT cytoskeleton, and are characterized by centriole-bearing centrosomes, which function as microtubule organizing centres. SCOPE: Extensive electron microscope and immunofluorescence studies of MT organization in different types of brown algal cells have shown that MTs constitute a major cytoskeletal component, indispensable for cell morphogenesis. Apart from participating in mitosis and cytokinesis, they are also involved in the expression and maintenance of polarity of particular cell types. Disruption of MTs after Nocodazole treatment inhibits cell growth, causing bulging and/or bending of apical cells, thickening of the tip cell wall, and affecting the nuclear positioning. Staining of F-actin using Rhodamine-Phalloidin, revealed a rich network consisting of perinuclear, endoplasmic and cortical AFs. AFs participate in mitosis by the organization of an F-actin spindle and in cytokinesis by an F-actin disc. They are also involved in the maintenance of polarity of apical cells, as well as in lateral branch initiation. The cortical system of AFs was found related to the orientation of cellulose microfibrils (MFs), and therefore to cell wall morphogenesis. This is expressed by the coincidence in the orientation between cortical AFs and the depositing MFs. Treatment with cytochalasin B inhibits mitosis and cytokinesis, as well as tip growth of apical cells, and causes abnormal deposition of MFs. CONCLUSIONS: Both the cytoskeletal elements studied so far, i.e. MTs and AFs are implicated in brown algal cell morphogenesis, expressed in their relationship with cell wall morphogenesis, polarization, spindle organization and cytokinetic mechanism. The novelty is the role of AFs and their possible co-operation with MTs.     

The chemistry of brown algae

The enormous and self-replenishing supplies—perhaps 200 or 300 million tons—of these seaweeds in the oceans of the world have been commercially exploited so far primarily in the production of alginic acid, but the other carbohydrates, proteins, lipids, vitamins, enzymes and antibacterial substances in them and discussed here may hold even greater values.     

Cytoplasmic inheritance of organelles in brown algae

Brown algae, together with diatoms and chrysophytes, are a member of the heterokonts. They have either a characteristic life cycle of diplohaplontic alternation of gametophytic and sporophytic generations that are isomorphic or heteromorphic, or a diplontic life cycle. Isogamy, anisogamy and oogamy have been recognized as the mode of sexual reproduction. Brown algae are the characteristic group having elaborated multicellular organization within the heterokonts. In this study, cytoplasmic inheritance of chloroplasts, mitochondria and centrioles was examined, with special focus on sexual reproduction and subsequent zygote development. In oogamy, chloroplasts and mitochondria are inherited maternally. In isogamy, chloroplasts in sporophyte cells are inherited biparentally (maternal or paternal); however, mitochondria (or mitochondrial DNA) derived from the female gamete only remained during zygote development after fertilization. Centrioles in zygotes are definitely derived from the male gamete, irrespective of the sexual reproduction pattern. Female centrioles in zygotes are selectively broken down within 1–2 h after fertilization. The remaining male centrioles play a crucial role as a part of the centrosome for microtubule organization, mitosis, determination of the cytokinetic plane and cytokinesis, as well as for maintaining multicellularity and regular morphogenesis in brown algae.     

Light-induced absorbance changes of carotenoids in brown algae

Light-induced absorbance changes were studied for brown algae with 23 species and a pronounced absorbance change around 563 nm was found in all algae examined. 3-(3,4-dichlorophenyl)-1,1-dimethylurea and gramicidin J suppressed the initial rate and the magnitude of the absorbance change. Carbonylcyanidem-chlorophenylhydrazone did not affect the initial rate but decreased the maximum level of the change. All thalli and the chloroplasts tested had an absorption band at around 540 nm due to fucoxanthin which accounted for about 70–90% of the total carotenoids in brown algae. It is proposed that the 563 nm-change is caused by the red shift of fucoxanthin responding to the light-induced change in the membrane potential of the thylakoid system.     

Isolation of water-soluble alginate from brown algae

Summary Water-soluble alginate was obtained from an aqueous extract of Kjellmaniella crassifolia by precipitation with HCl, calcium acetate or 20% ethanol in the presence of 0.05 M MgCl₂ Of these precipitation procedures, MgCl₂-ethanol gave the purest alginate preparation as judged by electrophoresis. The thin-layer and gas-liquid chromatography of its acid hydrolysate, and the IR spectra analysis of the whole alginate, suggested that the water-soluble alginate is similar to ordinary water-insoluble and alkali-soluble alginate such as Kelco alginate.However, the alginate obtained in the present work contained a great excess of mannuronic acid residues, giving an M:G ratio of about 13. Its molecular weight distribution was rather broad as with Kelco alginate, but the molecular weight of its major component was estimated to be 500 000 amu, whereas that Kelco alginate measured on the same column under the same condition was 1 700 000 amu. This suggests that water-soluble alginate was far smaller in average molecular size than Kelco alginate.     

Phyconanotechnology: synthesis of silver nanoparticles using brown marine algae Cystophora moniliformis and their characterisation

Biosynthesis of metallic nanoparticles is a relatively new developing area of nanotechnology which has economic and environmentally friendly advantages over conventional chemical and physical methods of synthesis. In this paper, we report for the first time, on the synthesis of silver nanoparticles (AgNPs) using the Australasian brown marine algae Cystophora moniliformis. An extract of this alga was used as a reducing and stabilising agent. Temperature-dependent variation of the size of the AgNPs was observed. Agglomeration of the nanoparticles was observed at high temperatures. The average size of the AgNPs formed at temperatures?<?65°C was 75 nm, whereas they were >2 μm at higher temperatures. The X-ray diffraction (XRD) pattern revealed face-centered cubic structure of the formed Ag nanoparticles.     

Anticoagulant activity of fucoidans from brown algae

The anticoagulant activity of polysaccharide fucoidans from 11 species of brown algae was studied. The anticoagulant activity was measured by the activated partial thromboplastin time (APTT), prothrombin time, and thrombin time. Inhibitory action of these fucoidans significantly varied from one species to another. Fucoidans from Laminaria saccharina and Fucus distichus exhibited high anticoagulant activity, while fucoidans from Cladosiphon okamuranus and Analipus japonicus were almost inactive. Other fucoidans exhibited intermediate inhibitory activity. The inhibitory effect of fucoidans on thrombin and factor Xa was investigated in the presence or in the absence of natural thrombin inhibitor, antithrombin III (AT III). In contrast to the best-studied anticoagulant, heparin, most of these fucoidans inhibited thrombin in the absence of AT III. In the presence of AT III the inhibitory effect of fucoidans considerably increased. In contrast to heparin, fucoidans weakly influenced factor Xa activity in the presence of AT III and their inhibitory effect was not observed in the absence of AT III. There was no correlation between the anticoagulant activities of this series of fucoidans and their anti-inflammatory action, studied earlier. It is suggested that these two types of fucoidan activities depend on different structural features of fucoidans. Results of this study demonstrate a possibility of preparation of fucoidans with high anti-inflammatory activity but low anticoagulant activity. Anticoagulant activity of the fucoidans did not exhibit direct dependence on the content of fucose, the other neutral sugars and sulfates; no dependence was also found between the anticoagulant activity and the structure of the backbone of their molecules.     

99 Teaching biological research using brown algae

Deserts are not thought of as biodiversity hotspots, but desert microbiotic crust communities represent a largely unknown community type rich in diversity of eukaryotic and prokaryotic taxa. These ecologically important communities have received much attention because of their role in nutrient cycling and soil stabilization in deserts, but they defy characterization by the traditional approach to assessing biodiversity by counting species. While genetically diverse, taxa characteristic of desert crusts are difficult to identify to the species level due to convergent evolution toward simple morphologies, phenotypic plasticity, or poor knowledge about particular lineages. Focusing on the green algae, we show that while biodiversity is difficult to measure in these communities, phylodiversity provides a surrogate measure that more accurately portrays the diversity of organisms, and one that is standardized across the variety of life histories, reproductive strategies and morphological variability that creates problems with species-counting measures. Bayesian phylogenetic inference uses MCMC simulation to generate phylogenies sampled in proportion to their Bayesian posterior probability. The length of a segment in any of these trees corresponds to the amount of change in the lineage, measured as the expected number of substitutions/nucleotide site. Comparisons of segment lengths corresponding to desert vs. other green algal lineages provides a means of addressing questions of relative genetic diversity, or phylodiversity, without complications arising from the difficulty of counting species. Our data illustrate the impact of desert green algae to overall knowledge of the green algal phylogenetic tree.