A comparison of the morpho-cytology and chemical composition of the two forms of the cyanobacterium, <Emphasis Type="Italic">Nostoc commune</Emphasis> Vauch., from the Philippines and Japan

Nostoc commune Vauch. is one of the few freshwater cyanobacteria that has been used as human food. But its commercial production has been elusive. This prompted us to investigate further on the chemical composition and morpho-cytological characteristics of the discoid and spherical forms of the alga from the Philippines and Japan. Light microscopy of the two forms revealed that they consisted of irregularly coiled, unbranched, heterocystous filaments. Transmission electron microscopy showed that a trichome was enclosed by a 14 μm  thick mucilaginous sheath (extracellular polysaccharide, EPS). A colonial sheath enveloped a spherical colony that was made up of a blue-green outer core that enclosed an inner, whitish, fleshy core, while the discoid form was a deflated or desiccated form of the spherical form. Cytologically, the outer core of the spherical colony (PS) had significantly (p < 0.01) shorter filaments and higher heterocyst frequency than the discoid colony while the discoid type had greater number of detached heterocysts than the other type. Chemical analyses revealed that the cyanobacterium had 34–45% oxalate-oxalic acid soluble substances (OOSS), a dietary fiber that was found to be in higher concentration among the discoid forms than the spherical forms. The major components of OOSS were identified as glucuronic and galacturonic acids that may play a role in modulating water flow in the glycans of the mucilaginous sheath. There were 17 amino acids identified. Philippine spherical (PS) colonies yielded generally higher concentration for each of these amino acids than the discoid types (PD and JD) except for phenylalanine, aspartic acid, and proline. There were six soluble proteins identified in the samples with the following molecular weights in kDa: 73, 55, 39, 36, 29, and 14.4. A protein band of 55 kDa was common to all types of colonies while 73 kDa was identified in the spherical form (PS) and faintly in the discoid form (JD). The protein bands of 39, 36, 29, and 14.4 kDa were found distinctly among the discoid forms (desiccated types) regardless of origin but absent in the spherical forms. In vitro protein digestion was improved, by as much as 30%, when the pigments were extracted. However, the presence of phenolic compounds could also affect protein digestion. Morpho-cytological studies and chemical analyses showed that N. commune of the same colony form generally had the same characteristics regardless of their origin. Although the common traits were more obviously observed among the discoid colonies. However, protein, crude lipid, and chlorophyll a concentrations were found to be more dependent on the age and culture condition of the cyanobacterium than on colony form or origin. Presented at the 6th Meeting of the Asia Pacific Society of Applied Phycology, Manila, Philippines.     

Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community

Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community.     

Isolation,characterization and localization of extracellular polymeric substances from the cyanobacterium Arthrospira platensis strain MMG-9

Arthrospira platensis is a cyanobacterium known for its nutritional value and secondary metabolites. Extracellular polymeric substances (EPS) are an important trait of most cyanobacteria, including A. platensis. Here, we extracted and analysed different fractions of EPS from a locally isolated strain of A. platensis. Three different fractions of EPS were distinguished. These were EPS released into the medium (REPS), EPS loosely bound to the organism (LEPS) and EPS tightly bound to the organism (TEPS), which were extracted by different procedures. The LEPS fraction was smaller than the other two fractions. The EPS of A. platensis exhibited high diversity. Total protein and carbohydrate content was determined in each of these fractions. The largest amount of total carbohydrates and total proteins was in the TEPS fraction. Eight sugar moieties were detected and analysed in all EPS fractions using HPAE-PAD. Fructose, mannose and ribose were rare sugar residues in all fractions of EPS. With the exception of fructose, all sugars tested for were detected in TEPS. The amount of sugars detected was significantly higher in TEPS compared with the two other fractions, especially for galactose, xylose and glucose. The EPS were localized by confocal laser scanning microscopy (CLSM) after staining with different fluorescent dyes and it was found that A. platensis possessed a thick and smooth layer of EPS around the spiral trichomes.     

Activation of farnesoid X receptor attenuates hepatic injury in a murine model of alcoholic liver disease

Alcoholic liver disease (ALD) is a common cause of advanced liver disease, and considered as a major risk factor of morbidity and mortality worldwide. Hepatic cholestasis is a pathophysiological feature observed in all stages of ALD. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily, and plays an essential role in the regulation of bile acid, lipid and glucose homeostasis. However, the role of FXR in the pathogenesis and progression of ALD remains largely unknown. Mice were fed Lieber-DeCarli ethanol diet or an isocaloric control diet. We used a specific agonist of FXR WAY-362450 to study the effect of pharmacological activation of FXR in alcoholic liver disease. In this study, we demonstrated that FXR activity was impaired by chronic ethanol ingestion in a murine model of ALD. Activation of FXR by specific agonist WAY-362450 protected mice from the development of ALD. We also found that WAY-362450 treatment rescued FXR activity, suppressed ethanol-induced Cyp2e1 up-regulation and attenuated oxidative stress in liver. Our results highlight a key role of FXR in the modulation of ALD development, and propose specific FXR agonists for the treatment of ALD patients.     

Effect of the addition of inert cellulose substrates to grape must on Saccharomyces cerevisiae diversity and the evolution of alcoholic fermentation

AIMS: To study the addition of cellulose-based adjuvant as a resource to offset the negative effects produced by grape juice clarification during alcoholic fermentations. METHODS AND RESULTS: The effect of the addition of two kinds of inert cellulose substrates in white wine vinification was investigated in two different musts. In one of these musts, stuck fermentations were detected. One of the types of cellulose examined had a fining effect, which caused a decrease in the number of viable yeasts in the medium and altered the distribution and frequency of the clones, which performed the fermentation. The other cellulose substrate made the medium cloudier but did not alter the distribution of yeasts in comparison with the control. CONCLUSIONS: The behaviour of the inert cellulose substrates on vinification depends on its physical characteristics and its capacity for making the must cloudy. SIGNIFICANCE AND IMPACT OF THE STUDY: The addition of inert cellulose substrates in white wine vinification improves the fermentation process and the quality of wines obtained. This effect is more noticeable in difficult fermentations. One variety of cellulose showed an inhibitory effect on Torulaspora delbrueckii yeasts.     

The oxidative damage of plasmid DNA by ascorbic acid derivatives in vitro: the first research on the relationship between the structure of ascorbic acid and the oxidative damage of plasmid DNA

To study the structure-function relationship of the oxidative-damage effect of ascorbic acid, we have focused on the interaction between plasmid DNA pUC19 and a series of ascorbic acid derivatives modified on different OH groups in the presence of transition metal ions. Some ascorbic acid derivatives can selectively cleave plasmid DNA from Form I to Form II in the presence of low concentration of Cu2+ just like ascorbic acid itself, while other derivatives oxidatively damage plasmid DNA slightly. We found that those derivatives with unattached 2-OH and 3-OH groups retain the ability to cleave the plasmid DNA. The derivatives that have been methylated on 2-OH or 3-OH can only cleave plasmid DNA softly, and those derivatives that have been protected on both 2-OH and 3-OH can hardly exert an oxidative damage on plasmid DNA under the same condition. Form these results, we can draw the conclusion that 2-OH and 3-OH groups of the ascorbic acid molecule contribute most to this biological activity.     

Changes in blood plasma volume in rats during ontogenesis

The dynamics of blood plasma volume were studied for the first time in rats during ontogenesis. The significance of blood plasma volume is estimated in the transport of physiologically active substances to cells and target organs during development. The blood plasma volume was measured in male and female rats during embryogenesis on day 18 (E18), perinatal development on E21 and day 3 of postnatal development (P3), and postnatal development on P15 and P30. Blood plasma volume was measured using Evans Blue dye method. Body mass was determined in the same animals and correlation was estimated between the blood plasma volume and body mass. The plasma volume increased 1.9-fold from E18 to E21, 1.4-fold from E21 to P3, 2.1-fold from P3 to P15, and 3.4-fold from P15 to P30. The body mass increased 5-fold from E18 to E21, 2-fold from E21 to P3, 2.3-fold from P3 to P15, and 3.2-fold from P15 to P30. The ratio of blood plasma to body mass was the highest on E18 (19%) and decreased twice by E21. This index varied from 5.4 to 4.8% during postnatal development. No sex-related differences in these indices were found in rats. The results obtained make it possible to determine the total content of physiologically active substances on the basis of their plasma concentration and, thereby, estimate the efficiency of secretory organs.     

Evaluation of antifungal activity of food additives against soilborne phytopathogenic fungi

The efficacy of eight food additives as possible alternatives to synthetic fungicides for the control of soilborne pathogens, Fusarium oxysporum f. sp. melonis, Macrophomina phaseolina, Rhizoctonia solani, and Sclerotinia sclerotiorum was evaluated in this study. A preliminary selection of food additives was performed through in vitro tests. The ED₅₀, minimum inhibition concentration (MIC), and minimum fungicidal concentration (MFC) values showed that ammonium bicarbonate and potassium sorbate were more toxic to soilborne pathogens compared to other food additives with few exceptions and, therefore selected for further testing in soil. The inhibitory and fungistatic efficacy potassium sorbate were higher than that of ammonium bicarbonate in in vitro tests. Potassium sorbate completely inhibited F. oxysporum f. sp. melonis, M. phaseolina, and R. solani at 0.6% in soil tests. In contrast ammonium bicarbonate at 0.6% was inferior compared to potassium sorbate. Ammonium bicarbonate achieved to control all fungi at 2% that is the highest concentration used in this study. Potassium sorbate showed higher toxicity to all fungi compared to ammonium bicarbonate in soil tests. Both ammonium bicarbonate and potassium sorbate increased the pH of soil. The rate of pH increase was higher in ammonium bicarbonate.     

Ground and excited state proton transfer and antioxidant activity of 7-hydroxyflavone in model membranes: absorption and fluorescence spectroscopic studies

Steady state and time resolved fluorescence spectroscopy have been used to probe microenvironments of the therapeutically active intrinsically fluorescent flavonoid, 7-hydroxyflavone (7-HF), in model membranes consisting of multilamellar phosphatidylcholine liposomes. Additionally, the antioxidant effects of 7-HF against lipid peroxidation have been evaluated using spectrophotometric assay. Large Stokes shifted emissions with distinct spectroscopic signatures, are observed from the excited state proton transfer (ESPT) tautomer (which is generated by a solvent mediated mechanism) and the ground state anion of 7-HF. The neutral (7-HFN) and anionic (7-HFA) species' appear to be located in the non-polar acyl chain and the polar head group regions of the lipid vesicles respectively. The partition coefficients of 7-HFN and 7-HFA in these vesicles have also been estimated using their intrinsic fluorescence. Anisotropy (r) versus temperature (T) measurements reveal the utility of the tautomer fluorescence anisotropy as a sensitive parameter for exploring structural changes in the membranes. Fluorescence decay kinetics studies indicate heterogeneity in the microenvironments of both 7-HFN and 7-HFA. Furthermore, we demonstrate that lipid peroxidation of the model membranes is partially arrested upon 7-HF binding, suggesting its potential usefulness as an inhibitor of peroxidative damage of cell membranes.     

Speciation of iodine in high iodine groundwater in china associated with goitre and hypothyroidism

Iodine intake affects the occurrence of disease in a population. Excessive iodine intake may be caused by a high iodine content of drinking water. Tap water in few locations in Europe contains up to 139 μg/L mostly bound to humic substances, probably leaching from marine sediments in the aquifers. Even higher iodine contents have been found in Chinese waters, previously shown to associate with goitre and hypothyroidism. The aims were to elucidate speciation of high iodine groundwater from deep wells in China and to compare with high iodine waters from Europe. Water was sampled from eight wells in five villages along Bohai Bay, China. Macro-molecules and low molecular weight (MW) substances were separated by size exclusion chromatography (high performance liquid chromatography, Superose 12 HR 10/30, buffer 0.1 M Tris, pH 7.0). Organic material was evaluated by A280 and iodine in fractions measured by the Ce/As method after alkaline incineration. Iodine content of well water varied from 135 to 880 μg/L (median 287 μg/L). The amount of organic material in water was low with A280, <1–5 mAU. The chromatographic traces were similar between samples: One peak of iodine eluted around K _AV 0.65 corresponding to MW 5 kDa (humic substances) and one peak at V _total (iodide/low MW substances). The fraction of iodine in macro-molecules, suggested to be humic substances, varied from 8% to 70% (median 27%). Iodine and peak absorbance were associated (p = 0.006). In conclusion, iodine in iodine-rich deep well water in northern China may have marine origin and may associate with humic substances, comparable to shallow well iodine-rich water in Europe. High iodine intake from iodine-rich water suggests the cause of endemic goitre and hypothyroidism in some areas in China being iodine.