Comparative Spectroscopic and Electrochemical Study of V(V)-Substituted Keggin-Type Phosphomolybdates and -Tungstates

Vanadium-substituted Keggin-type heteropolyanions have been studied for a wide variety of applications, ranging from catalysis to antiviral/antimicrobial agents. While the V-substituted phosphomolybdates [PVxMo12−xO40](3+x)− have been well investigated in this context, comparatively little is known about the corresponding phosphotungstates [PVxW12-xO40](3+x)−. We have succeeded in synthesizing the sodium salts of the whole series [PVxW12−xO40](3+x)−, for x = 1 to 6, and characterised them spectroscopically (FT-IR, UV-Vis, 31P-, and 51V-NMR) and electrochemically (CV and SWV). Thereby, direct comparisons between the vanadium-substituted phosphomolybdates and -tungstates, with substitution degrees from 1 to 6, can be established, which provides a solid basis for further investigations of potential applications.

Megapixel multi-elemental imaging by Laser-Induced Breakdown Spectroscopy, a technology with considerable potential for paleoclimate studies

Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Moreover, the analysis of large samples (>few cm²) with any of these methods remains very challenging due to their relatively low acquisition speed (~1–10 Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 μm) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications.

Inhibition of plastocyanin to P(700)(+) electron transfer in Chlamydomonas reinhardtii by hyperosmotic stress

Oxygen electrode and fluorescence studies demonstrate that linear electron transport in the freshwater alga Chlamydomonas reinhardtii can be completely abolished by abrupt hyperosmotic shock. We show that the most likely primary site of inhibition of electron transfer by hyperosmotic shock is a blockage of electron transfer between plastocyanin (PC) or cytochrome c(6) and P(700). The effects on this reaction were reversible upon dilution of the osmolytes and the stability of plastocyanin or photosystem (PS) I was unaffected. Electron micrographs of osmotically shocked cells showed a significant decrease in the thylakoid lumen volume. Comparison of estimated lumenal width with the x-ray structures of plastocyanin and PS I suggest that lumenal space contracts during HOS so as to hinder the movement of docking to PS I of plastocyanin or cytochrome c(6).

Inhibition of plastocyanin to P(700)(+) electron transfer in Chlamydomonas reinhardtii by hyperosmotic stress

Oxygen electrode and fluorescence studies demonstrate that linear electron transport in the freshwater alga Chlamydomonas reinhardtii can be completely abolished by abrupt hyperosmotic shock. We show that the most likely primary site of inhibition of electron transfer by hyperosmotic shock is a blockage of electron transfer between plastocyanin (PC) or cytochrome c(6) and P(700). The effects on this reaction were reversible upon dilution of the osmolytes and the stability of plastocyanin or photosystem (PS) I was unaffected. Electron micrographs of osmotically shocked cells showed a significant decrease in the thylakoid lumen volume. Comparison of estimated lumenal width with the x-ray structures of plastocyanin and PS I suggest that lumenal space contracts during HOS so as to hinder the movement of docking to PS I of plastocyanin or cytochrome c(6).

Contribution of electric field (Delta psi) to steady-state transthylakoid proton motive force (pmf) in vitro and in vivo. control of pmf parsing into Delta psi and Delta pH by ionic strength

The observed levels of Delta G(ATP) in chloroplasts, as well as the activation behavior of the CF(1)CF(0)-ATP synthase, suggest a minimum transthylakoid proton motive force (pmf) equivalent to a Delta pH of approximately 2.5 units. If, as is commonly believed, all transthylakoid pmf is stored as Delta pH, this would indicate a lumen pH of less than approximately 5. In contrast, we have presented evidence that the pH of the thylakoid lumen does not drop below pH approximately 5.8 [Kramer, D. M., Sacksteder, C. A., and Cruz, J. A. (1999) Photosynth. Res. 60, 151-163], leading us to propose that Delta psi can contribute to steady-state pmf. In this work, it is demonstrated, through assays on isolated thylakoids and computer simulations, that thylakoids can store a substantial fraction of pmf as Delta psi, provided that the activities of ions permeable to the thylakoid membrane in the chloroplast stromal compartment are relatively low and the buffering capacity (beta) for protons of the lumen is relatively high. Measurements of the light-induced electrochromic shift (ECS) confirm the ionic strength behavior of steady-state Delta psi in isolated, partially uncoupled thylakoids. Measurements of the ECS in intact plants illuminated for 65 s were consistent with low concentrations of permeable ions and approximately 50% storage of pmf as Delta psi. We propose that the plant cell, possibly at the level of the inner chloroplast envelope, can control the parsing of pmf into Delta psi and Delta pH by regulating the ionic strength and balance of the chloroplast. In addition, this work demonstrates that, under certain conditions, the kinetics of the light-induced ECS can be used to estimate the fractions of pmf stored as Delta psi and Delta pH both in vitro and in vivo.

Dietary habits and nutritional status in adolescents over Europe--Southern Europe

A literature review of the data on dietary habits, food consumption and nutritional status of adolescents of Southern European countries was performed. Snacking seems to be less frequent and the frequency of eating out in fast food restaurants is much lower than in the USA and in some Nordic Countries. A nutrient pattern rich in total fat (around 40% of the energy intake), in saturated fatty acids (around 13% of the energy intake) and mainly in monounsaturated fatty acids (17-19% of the energy intake), due to a high consumption of olive oil, is often observed in Spanish and Greek adolescents. In Portugal, the percentage of the energy provided by fat is relatively low (31-33% of the energy intake) and in Italy the situation is intermediate regarding total fat, but the intake of olive oil is also high. This means that two important characteristics of the Mediterranean diet, a low consumption of saturated fatty acids and a high intake of carbohydrates have been lost. Regarding micronutrients, there seems to exist a risk of deficiency, particularly for calcium, iron and zinc. The prevalence of overweight/obesity is high, around 15-25%, being higher than in the Nordic countries but lower than in the USA. There is no clear indication of trends, due to the different methods and criteria used to define obesity. The serum cholesterol levels of adolescents has increased during the last two decades in Spain, Greece and Italy, and nowadays are similar to those in the USA, but still lower than in the Nordic countries. In Portuguese adolescents, the cholesterol levels seem to be lower, but the situation is not well known.

Increased chitin synthesis in response to type II myosin deficiency in Saccharomyces cerevisiae

We reported previously that the chitin content in cell walls of type II myosin-deficient Saccharomyces cerevisiae strains is increased relative to wild-type cells suggesting that increased chitin synthesis is induced in these strains. In the present study, we have performed enzyme activity assays for chitin synthases 1, 2, and 3 to determine the enzyme isoform(s) involved. To determine if transcriptional regulation is involved, we conducted quantitative mRNA assays of the corresponding chitin synthase genes. We show that the enzyme activities of all three chitin synthases increase substantially over the wild-type strain while eight- and twofold increases in the mRNA levels for chitin synthases 1 and 3 were detected. Increases in enzyme activities and mRNA levels were not proportional. We conclude that the enzyme activities for all three chitin synthases are elevated in this strain and that this increase is mediated mainly by a posttranslational mechanism(s). The heightened sensitivity to osmotic stress and the corresponding increase in cell wall chitin content reported in these strains are consistent with a compensatory "stress response" mechanism induced by abnormal cell wall assembly.

Carboxylate groups on the manganese-stabilizing protein are required for its efficient binding to photosystem II

The effects of the modification of carboxylate groups on the manganese-stabilizing protein of photosystem II were investigated. Carboxylate groups (including possibly the C-terminus) on the manganese-stabilizing protein were modified with glycine methyl ester in a reaction facilitated by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The manganese-stabilizing protein that was modified while associated with NaCl-washed photosystem II membranes contained 1-2 modified carboxylates, whereas the protein that was modified while free in solution contained 4 modified carboxylates. Both types of modified protein could reconstitute oxygen evolution at high manganese-stabilizing protein to photosystem II reaction center ratios. However, the protein that had been modified in solution exhibited a dramatically altered binding affinity for photosystem II. No such alteration in binding affinity was observed for the protein that had been modified while associated with the photosystem. Mapping of the sites of modification was carried out by trypsin and Staphylococcus V8 protease digestion of the modified proteins and analysis by matrix-assisted laser desorption/ionization mass spectrometry. These studies indicated that the domains (157)D-(168)D and (212)E-(247)Q (C-terminus) are labeled only when the manganese-stabilizing protein is modified in solution. Modified carboxylates in these domains are responsible for the altered binding affinity of this protein for the photosystem.

[Nutrition assessment of the elderly based on results of the SENECA Study "Nutrition and the elderly in Europe"]

The SENECA Study "Nutrition and the elderly in Europe" investigates men and women born 1913-1918 in 20 small traditional towns in Europe. At the age of 74-79 years subjective health was satisfactory or good in 95% of 399 men and 93% of 414 women in 6 study towns. In these subjects suboptimal nutritional blood values were virtually nonexistent. Food intake was low in energy and rich in protein and fat. Lowest European recommended dietary allowances were not reached by all subjects. The even higher values recommended as potentially protective factors were not met by a substantial part of subjects with energy intakes below 6.3 MJ/d. Regularity of food intake was high and had increased over 4 years. Living alone did not adversely affect food intake while low economic situation did.

Flow cytometry analysis of cell cycle in myosin II-deficient yeast

OBJECTIVE

To determine whether cell cycle changes can be detected in myosin II-deficient cells using flow cytometry techniques.

BACKGROUND

Although the primary role of myosin II (Myo1p) in the yeast Saccharomyces cerevisiae is in cytokinesis we have reported that this conventional myosin also appears to influence the regulation of cell wall metabolism as indicated by increases in the expression of chitin metabolizing enzymes in a null mutant of the MYO1 gene. The expression of these enzymes is known to be regulated in the cell cycle suggesting that cell cycle changes may alter their expression.

METHODS

Flow cytometry was employed to assess the nuclear DNA content of logarithmic yeast cell cultures as a means of determining changes in the cell cycle of Myo1p-deficient cells.

RESULTS

Significant changes were observed in the Myo1p-deficient strain suggesting that these cells are arrested in G2/M-phase of the cell cycle.

CONCLUSIONS

Based on the results of this preliminary study, we propose a model in which the increased activity of chitin metabolizing enzymes may be explained by a mitotic arrest in these cells.

Elevated expression of chitinase 1 and chitin synthesis in myosin II-deficient Saccharomyces cerevisiae

To determine if the attached cells formed in Myosin II-deficient Saccharomyces cerevisiae result from deficient chitinase 1 (CTS1) expression, the activity of chitinase 1 was assayed. Secretion of this enzyme was not prevented by a MYO1 gene deficiency, and soluble and cell wall-associated Cts1p activity were increased approximately 5-fold and 20-fold, respectively, in these cells. The increase in soluble activity was correlated with an increase in enzyme levels. Likewise, intracellular chitinase activity was increased approximately 22-fold, and the chitin content of cell walls was elevated 2-fold. These data suggest that the origin of myo1-associated phenotypes is not due to deficient chitinase expression and may instead be due to a deregulation of cell wall metabolism in these cells.

Effect of folate supplementation on DNA methylation of rectal mucosa in patients with colonic adenomas: correlation with nutrient intake

We have evaluated the effect of folate supplementation (5 mg/day) on global deoxyribonucleic acid (DNA) methylation status of the rectal mucosa of 20 patients with resected colonic adenomas in a prospective, controlled, cross-over study. Baseline values of DNA methylation were inversely correlated with caloric (P = 0.03) and fat intake (P = 0.05) and patients harbouring multiple polyps consumed significantly more calories (P = 0.0006), fat (P = 0.009) and carbohydrates (P = 0.009) as compared to patients having one single lesion. Folate supplementation resulted in a significant decrease of DNA hypomethylation in 7/20 patients (P = 0.05) which returned to previous values after placebo treatment. This effect was significantly correlated with number of polyps, with all the responders presenting one single lesion, whereas 8/13 of the non-responders had multiple ones (chi2 = 7.17, P = 0.007). In conclusion, folate supplementation may decrease degree of DNA hypomethylation, but only in patients with one single polyp. In those with multiple lesions, other nutritional factors such as caloric and fat intake, may be more determinant.

Molecular dissection of the epsilon subunit of the chloroplast ATP synthase of spinach

The gene encoding the epsilon subunit (atpE) of the chloroplast ATP synthase of Spinacia oleracea has been overexpressed in Escherichia coli. The recombinant protein can be solubilized in 8 M urea and directly diluted into buffer containing ethanol and glycerol to obtain epsilon that is as biologically active as epsilon purified from chloroplast-coupling factor 1 (CF1). Recombinant epsilon folded in this manner inhibits the ATPase activity of soluble and membrane-bound CF1 deficient in epsilon and restores proton impermeability to thylakoid membranes reconstituted with CF1 deficient in epsilon. Site-directed mutagenesis was used to generate truncations and single amino acid substitutions in the primary structure of epsilon. In the five mutants tested, alterations that weaken ATPase inhibition by recombinant epsilon affect its ability to restore proton impermeability to a similar extent, with one exception. Substitution of histidine-37 with arginine appears to uncouple ATPase inhibition and the restoration of proton impermeability. As in the case of E. coli, it appears that N-terminal truncations of the epsilon subunit have more profound effects than C-terminal deletions on the function of epsilon. Recombinant epsilon with six amino acids deleted from the C terminus, which is the only region of significant mismatch between the epsilon of spinach and the epsilon of Pisum sativum, inhibits ATPase activity with a reduced potency similar to that of purified pea epsilon. Four of the six amino acids are serine or threonine. These hydroxylated amino acids may be important in epsilon-CF1 interactions.

Intake of energy and nutrients. Euronut SENECA investigators

As part of the Euronut SENECA study, food consumption has been assessed in 1217 men and 1241 women, born between 1913 and 1918 and living in 18 towns in 12 European countries. The method used was a standardized modified dietary history, including a 3-day estimated record and a food frequency list based on local food patterns. Intakes of energy, protein, fat, carbohydrate, fatty acids, cholesterol and alcohol are described in this paper. As expected, a difference between men and women in energy and nutrient intake was observed in all towns. There was a great variation between towns in mean dietary intakes of all dietary components. Mean energy intake of men ranged from 12.7 MJ in Marki (Poland) to 8.2 MJ in Yverdon (Switzerland) and Chateau Renault-Amboise (France). For women the range was from 10.9 MJ in Marki (Poland) to 6.3 MJ in Yverdon (Switzerland) and Vila Franca de Xira (Portugal). A geographical pattern can be detected for the intake of fatty acids. Intakes of saturated fat were lower in southern than in northern European towns. The calculated ratio for intakes of unsaturated and saturated fatty acids (polyunsaturated fatty acids plus monounsaturated fatty acids/saturated fatty acids) for all participants was higher in the southern European centres than in the northern centres and ranged from 2.7 in Markopoulo (Greece) to 1.2 in Elverum (Norway) and Marki (Poland). Alcohol consumption was considerable higher in men than in women. In men a north-south gradient in alcohol intake can be detected, with the highest intake in the two centres in Italy, where, on average 11% of energy intake was derived from alcohol.

Nutritional status: serum lipids. Euronut SENECA investigators

Serum lipid levels are considered to be one of the main risk factors for cardiovascular diseases in middle-aged men and women. The significance, however, of serum lipid metabolism as a cardiovascular disease risk factor in the elderly has yet to be clarified. This paper focuses upon the serum lipid levels of groups of elderly people from 18 centres with diversified socioeconomic backgrounds in 11 European countries. Serum cholesterol was measured with an enzymatic colorimetric method by autoanalyser in one laboratory and accuracy was checked by participation in the quality control programme of the Centre for Disease Control, Atlanta, GA, USA. Mean (+/- SD) serum cholesterol levels ranged from 6.56 +/- 0.66 mmol/l (Bellinzona, Switzerland) to 5.22 +/- 0.68 mmol/l (Coimbra, Portugal) in men, and in women from 7.77 +/- 1.61 mmol/l (Elverum, Norway) to 5.86 +/- 1.07 mmol/l (Anogia-Archanes/Greece). The mean levels of high-density lipoprotein (HDL) cholesterol ranged from 1.40 +/- 0.58 mmol/l (Chateau Renault-Amboise, France) to 1.05 +/- 0.28 mmol/l (Elverum, Norway) in men and from 1.62 +/- 0.41 mmol/l (Padua, Italy) to 1.23 +/- 0.29 mmol/l (Anogia-Archanes, Greece; Vila Franca de Xira, Portugal) in women. The highest median serum triglyceride values were found in Norway (Elverum) (men: 1.50 mmol/l, women: 1.75 mmol/l), and one of the French groups (Chateau Renault-Amboise) had the lowest median values (men: 1.07 mmol/l, women: 1.15 mmol/l). Significant differences between participating centres and between sexes were found for the following variables: serum cholesterol, HDL, and the ratio total HDL cholesterol/total cholesterol. For triglycerides the differences were significant only between centres, not between the sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Intake of vitamins and minerals. Euronut SENECA investigators

In 18 towns of 12 European countries, 1217 men and 1241 women born between 1913 and 1918 participated in a dietary survey (modified dietary history). Each country used its own nutrient data bank for the conversion of food intake data into vitamin and mineral intakes. Information on the use of nutrient supplements was collected through a questionnaire answered by the participants. Enormous variability in nutrient dietary intake was observed between and even within the different sites. The dietary intake of vitamin A was higher in northern towns and, conversely, the intake of beta-carotene and vitamin C was lower. A considerable percentage of the elderly in some towns had intakes of some nutrients below the lowest European recommended daily intakes (RDIs) and so might be at risk of vitamin and mineral deficiencies. Women in almost all towns had diets of higher nutrient density than men, except for iron. There was great variability in supplementation practices between different towns, even within a country. In northern towns, supplements were used much more frequently than in the other sites, but their use was not nutrition-oriented. Sometimes vitamin supplements were taken in large quantities, with risk of toxicity. Differences between the sexes in supplementation practices were not consistent.