Whole-grain intake and its inverse relationships with fatty acids intake among multiethnic Malaysian schoolchildren.

INTRODUCTION: Little is known about the relationship of whole-grain intake with dietary fatty acids intake. The present study aimed to assess the whole-grain intake and its relationships with dietary fatty acids intake among multiethnic schoolchildren in Kuala Lumpur, Malaysia. METHODS: This cross-sectional study was conducted among 392 schoolchildren aged 9-11 years, cluster sampled from five randomly selected schools in Kuala Lumpur. Whole-grain and fatty acids intakes were assessed by 3-day, 24-h diet recalls. All whole-grain foods were considered irrespective of the amount of whole grain they contained. RESULTS: In total, 55.6% (n = 218) were whole-grain consumers. Mean (SD) daily intake of whole grain in the total sample was 5.13 (9.75) g day-1 . In the whole-grain consumer's only sample, mean (SD) intakes reached 9.23 (11.55) g day-1 . Significant inverse associations were found between whole-grain intake and saturated fatty acid (SAFA) intake (r = -0.357; P < 0.001), monosaturated fatty acid (MUFA) (r = -0.373; P < 0.001) and polyunsaturated fatty acid (PUFA) (r = -0.307; P < 0.001) intake. Furthermore, whole-grain intake was a significant predictor of SAFA (ß = -0.077; P = 0.004), MUFA (ß = -0.112; P = <0.001) and PUFA (ß = -0.202; P = <0.001) intakes, after controlling for sex, age and ethnicity. CONCLUSIONS: Whole-grain intake in Malaysia was well below recommendations. Schoolchildren who consumed higher whole grain tend to reduce fat intake; however, it would also reduce the SAFA, MUFA and PUFA intakes. Future collaboration may be conducted between industry, government and universities to promote unsaturated fatty acids-rich foods and whole-grain food, although not to promote processed whole-grain foods with a high sugar and salt content.

Physiological integration enhanced the tolerance of Cynodon dactylon to flooding.

Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration.

Photoinactivation of photosystem II complexes and photoprotection by non-functional neighbours in Capsicum annuum L. leaves.

Leaf segments from Capsicum annuum plants grown at 100 micromol photons m(-2) s(-1) (low light) or 500 micromol photons m(-2) s(-1) (high light) were illuminated at three irradiances and three temperatures for several hours. At various times, the remaining fraction (f) of functional photosystem II (PS II) complexes was measured by a chlorophyll fluorescence parameter (1/Fo -1/Fm, where Fo and Fm are the fluorescence yields corresponding to open and closed PS II traps, respectively), which was in turn calibrated by the oxygen yield per saturating single-turnover flash. During illumination of leaf segments in the presence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis, the decline of f from 1.0 to about 0.3 was mono-exponential. Thereafter, f declined much more slowly, the remaining fraction (approximately equals 0.2) being able to survive prolonged illumination. The results can be interpreted as being in support of the hypothesis that photoinactivated PS II complexes photoprotect functional neighbours (G. Oquist et al. 1992, Planta 186: 450-460), provided it is assumed that a photoinactivated PS II is initially only a weak quencher of excitation energy, but becomes a much stronger quencher during prolonged illumination when a substantial fraction of PS II complexes has also been photoinactivated. In the absence of lincomycin, photoinactivation and repair of PS II occur in parallel, allowing f to reach a steady-state value that is determined by the treatment irradiance, temperature and growth irradiance. The results obtained in the presence and absence of lincomycin are analysed according to a simple kinetic model which formally incorporates a conversion from weak to strong quenchers, yielding the rate coefficients of photoinactivation and of repair for various conditions, as well as gaining an insight into the influence off on the rate coefficient of photoinactivation. They demonstrate that the method is a convenient alternative to the use of radiolabelled amino acids for quantifying photoinactivation and repair of PS II in leaves.

Greening of intermittent-light-grown bean plants in continuous light: thylakoid components in relation to photosynthetic performance and capacity for photoprotection.

Phaseolus vulgaris (cvv. Windsor longpod and snap bean) plants, etiolated during germination, were exposed to intermittent light (2 min light every 2 hr) for up to 68 hr and then transferred to continuous white light. On transfer of the plants to continuous light (100 photons mumol m-2 s-1, 24 degrees C), the quantum yield of oxygen evolution increased two-fold in about 30 hr. The chlorophyll content per unit leaf area or unit fresh weight increased dramatically, but the fresh weight per unit leaf area was relatively constant. The changes were expressed on the basis of fresh weight or leaf area. On this basis, the contents of photosystem (PS) I and II increased in continuous light, by a factor of 3 and 8, respectively. While the chlorophyll b content and the contents of apoproteins of light-harvesting chlorophyll-protein complexes (LHCIIb, CP29, CP26 and CP24) increased markedly, neither the total carotenoid content nor the de-epoxidation state of the xanthophylls [ratio of zeaxanthin(Z) + antheraxanthin(A) to (Z + A + violaxanthin) was about 0.4)] responded significantly on transfer to continuous light. The fast rise of the flash-induced electrochromic signal (delta A518) was well correlated with the increases in PS I and PS II reaction centres, and with chlorophyll b and total carotenoid contents. The increase in the quantum yield of oxygen evolution during greening in continuous light is attributed to a more balanced distribution of excitation energy between the two photosystems, facilitated by the increased number of PS II units, the increased antenna size of each unit and the enhancement of grana formation. The chloroplast in intermittent light was found to contain abundant xanthophyll cycle pigments and the psbS gene product, presumably adequate for photoprotection in continuous light as soon as chlorophyll a/b- protein complexes are synthesized. The results suggest that greening in continuous light is accompanied by adjustments that include enhanced quantum efficiency of photosynthesis and development of a capacity for harmless dissipation of excess excitation energy.

Reduction in cab and psb A RNA transcripts in response to supplementary ultraviolet-B radiation.

The cab and psb A RNA transcript levels have been determined in Pisum sativum leaves exposed to supplementary ultraviolet-B radiation. The nuclear-encoded cab transcripts are reduced to low levels after only 4 h of UV-B treatment and are undetectable after 3 days exposure. In contrast, the chloroplast-encoded psb A transcript levels, although reduced, are present for at least 3 days. After short periods of UV-B exposure (4 h or 8 h), followed by recovery under control conditions, cab RNA transcript levels had not recovered after 1 day, but were re-established to ca. 60% of control levels after 2 more days. Increased irradiance during exposure to UV-B reduced the effect upon cab transcripts, although the decrease was still substantial. These results indicate rapid changes in the cellular regulation of gene expression in response to supplementary UV-B and suggest increased UV-B radiation may have profound consequences for future productivity of sensitive crop species.