An e.s.r. and spin-trapping study of the reactions of the SO4- radical with protein and nucleic acid constituents.

Reactions of the SO4- radical, generated by U.V. photolysis of Na2S2O8, were studied in aqueous solutions of amino acids, dipeptides, nucleic acid bases, nucleosides and nucleotides. The transient free radicals so formed were spin-trapped by t-nitrosobutane and identified by e.s.r. spectroscopy. The amino acids primarily undergo oxidative decarboxylation. The pKs of the ammonium groups of the spin-trapped decarboxylated radicals of glycine and alanine in D2O were determined to be 8.3 +/- 0.2. An oxidation product, which is the precursor of the decarboxylated radical, is tentatively identified for alanine, valine and isoleucine. Radicals formed by hydrogen abstraction by SO-4 are identified for leucine, serine, phenylalanine and 4-hydroxyproline. In dipeptides, SO-4 produces decarboxylation of the amino acid located at the carboxylate terminal residue. For gly-ala and ala-ala, radicals generated by hydrogen abstraction from the carboxylate terminal residue alanine were also characterized. Radicals centered on the C(5) carbon were observed for uracil, cytosine and thymine. For nucleosides and nucleotides, radicals situated on the base and/or the sugar moiety were assigned.     

Pattern of Resource Allocation of Six Plantago Species with Different Breeding Systems

Plantago exhibit great deal of differences in the breeding system. The reproductive effort calculated on the basis of, (i) dry biomass of foliar and floral parts and (ii) seed output-weight (mg) per unit leaf area (cm²), exhibits relation with breeding system. The predominantly inbreeding taxa invest higher reproductive effort compared to their outbreeding allies. In terms of sex allocation strategies, the outbreeding species like P. lanceolata, P. lagopus invest more to the development of floral features and to male functions. On the contrary, inbreeding species such as P. patagonica, P. drummondii, and P. ovata invest greater resources to the female function. Received 13 April 1998/ Accepted in revised form 6 November 1998     

Airborne Pollen Grains of Gurdur,Turkey

Ｔｈｃ ｐｏｌｌｅｎ ｇｒａｉｎｓ ｉｎ ｔｈｅ ａｔｍｏｓｐｈｅｒｅ ｏｆ Ｂｕｒｄｕｒ ｈａｖｅ ｂｅｅｎ ｓｔｕｄｉｅｄ ｆｏｒ ａ ｔｗｏ－ｙｅａｒ ｐｅｒｉｏｄ（１９９６ｔｈｒｏｕｇｈ １９９７）ｗｉｔｈ ａ Ｄｕｒｈａｍ ｓａｍｐｌｅｒ．Ａ ｔｏｔａｌ ｏｆ １１ ８８１ ｐｏｌｌｅｎ ｇｒａｉｎｓ ｂｅｌｏｎｇｉｎｓ ｔｏ ３９ ｔａｘａ ｈａｖｅ ｂｅｅｎ ｉｄｅｎｔｉ－ｆｉｅｄ     

Hydrated electron-initiated main-chain scission in peptides: an e.s.r. and spin-trapping study.

The reactions of hydrated electrons (eaq-) with 19 tripeptides were investigated. Hydrated electrons were produced by gamma-radiolysis of aqueous peptide solutions containing sufficient sodium formate to remove hydroxyl radicals and hydrogen atoms. t-Butanol was also used to scavenge hydroxyl radicals. The short-lived radicals formed by the reactions of eaq- with the peptides were spin-trapped with t-nitrosobutane to form stable nitroxide radicals and identified by e.s.r. spectroscopy. The tripeptides studied contained two glycine residues. Following the addition of eaq- to tripeptides, C-N bond scission was observed at three sites. Cleavage occurred between the nitrogen of the ammonium group and the alpha-carbon and between the nitrogen of the peptide linkage and the adjoining alpha-carbons. The radicals corresponding to each of these three types of scission were identified. From a comparison of the radical yields of the reaction of eaq- with ala, (ala)2, and poly-DL-ananine with an average degree of polymerization of 1800, it was shown that eaq-, can react with many carbonyl groups of poly-DL-alanine, leading to main-chain scission. Analogous reactions of eaq- with proteins and enzymes may be expected to lead to loss of biological activity.     

Whole Grain Intakes in the Diets Of Malaysian Children and Adolescents – Findings from the MyBreakfast Study

Background

Diets rich in whole grain are associated with several health benefits. Little is known however, about whole grain consumption patterns in Malaysia. The aim of this study was to assess whole grain intakes and dietary source in Malaysian children and adolescents.

Methods

This analysis is from the MyBreakfast study, a national cross sectional study investigating eating habits among primary and secondary school children throughout Malaysia, conducted in 2013. Children (n = 5,165) and adolescents (n = 2,947) who completed two days of dietary assessment using a food record or recall respectively were included. The whole grain content of foods was estimated mainly through the use of quantitative ingredient declarations on food labels. All wholegrain foods were considered irrespective of the amount of whole grain they contained.

Results

Overall, only 25% of children and 19% of adolescents were wholegrain consumers. Mean daily intakes in the total sample were 2.3g/d (SD 5.8g/d) in children and 1.7g/d (SD 4.7g/d) in adolescents and in the consumer’s only sample, mean intakes reached 9.1g/d (SD 8.6) and 9.2g/d (SD 7.1g/d) respectively. Wheat was the main grain source of whole grain while ready to eat breakfast cereals and hot cereals were the main food contributors. Less than 3% of the children and adolescents reached the US quantitative whole grain recommendation of 48g/day.

Conclusion

Whole grain is consumed by only a minority of Malaysian children and adolescents and even among consumers, intakes are well below recommendations. Efforts are needed to firstly understand the barriers to whole grain consumption among Malaysian children in order to design effective health promotion initiatives to promote an increase in whole grain consumption.