Relationships between gluten rheological properties and hearth loaf characteristics

The rheological properties of fresh gluten in small amplitude oscillation in shear (SAOS) and creep recovery after short application of stress was related to the hearth breadbaking performance of wheat flours using the multivariate statistics partial least squares (PLS) regression. The picture was completed by dough mixing and extensional properties, flour protein size distribution determined by SE-HPLC, and high molecular weight glutenin subunit (HMW-GS) composition. The sample set comprised 20 wheat cultivars grown at two different levels of nitrogen fertilizer in one location. Flours yielding stiffer and more elastic glutens, with higher elastic and viscous moduli (G' and G") and lower tan 8 values in SAOS, gave doughs that were better able to retain their shape during proving and baking, resulting in breads of high form ratios. Creep recovery measurements after short application of stress showed that glutens from flours of good breadmaking quality had high relative elastic recovery. The nitrogen fertilizer level affected the protein size distribution by an increase in monomeric proteins (gliadins), which gave glutens of higher tan delta and flatter bread loaves (lower form ratio).

Wheat protein quality in relation to baking performance evaluated by the Chorleywood bread process and a hearth bread baking test

The relationships between wheat protein quality and baking properties of 20 flour samples were studied for two breadmaking processes; a hearth bread test and the Chorleywood Bread Process (CBP). The strain hardening index obtained from dough inflation measurements, the proportion of unextractable polymeric protein, and mixing properties were among the variables found to be good indicators of protein quality and suitable for predicting potential baking quality of wheat flours. By partial least squares regression, flour and dough test variables were able to account for 71-93% of the variation in crumb texture, form ratio and volume of hearth loaves made using optimal mixing and fixed proving times. These protein quality variables were, however, not related to the volume of loaves produced by the CBP using mixing to constant work input and proving to constant height. On the other hand, variation in crumb texture of CBP loaves (54-55%) could be explained by protein quality. The results underline that the choice of baking procedure and loaf characteristics is vital in assessing the protein quality of flours. (C) 2003 Elsevier Ltd. All rights reserved.

Genistein blocks homocysteine-induced alterations in the proteome of human endothelial cells

Dietary isoflavones from soy are suggested to protect endothelial cells from damaging effects of endothelial stressors and thereby to prevent atherosclerosis. In search of the molecular targets of isoflavone action, we analyzed the effects of the major soy isoflavone, genistein, on changes in protein expression levels induced by the endothelial stressor homocysteine (Hcy) in EA.hy 926 endothelial cells. Proteins from cells exposed for 24 h to 25 mu M Hcy alone or in combination with 2.5 mu M genistein were separated by two-dimensional gel electrophoresis and those with altered spot intensities were identified by peptide mass fingerprinting, Genistein reversed Hcy-induced changes of proteins involved in metabolism, detoxification, and gene regulation: and some of those effects can be linked functionally to the antiatherosclerotic properties of the soy isoflavone. Alterations of steady-state levels of cytoskeletal proteins by genistein suggested an effect oil apoptosis. As a matter of fact genistein caused inhibition of Hcy-mediated apoptotic cell death as indicated by inhibition of DNA fragmentation and chromatin condensation. In conclusion, proteome analysis allows the rapid identification of cellular target proteins of genistein action in endothelial cells exposed to the endothelial stressor Hcy and therefore enables the identification of molecular pathways of its antiatherosclerotic action

The cannabinoid CB1 receptor antagonist SR141716 blocks the orexigenic effects of intrahypothalamic ghrelin

The paraventricular nucleus (PVN) of the hypothalamus plays a key role in the control of appetite and energy balance. Both ghrelin and cannabinoid receptor agonists increase food intake when administered into this nucleus: this study investigated possible interactions between the two systems in relation to eating. The orexigenic effect of ghrelin (100 pmol) when infused in to the PVN was reversed by a small, systemic dose of the CB1 cannabinoid receptor antagonist SR141716 (1 mg kg(-1)). This is the first demonstration of a functional relationship between brain ghrelin and endocannabinoid systems, and, although it needs to be further investigated, the effect of ghrelin on food intake when injected into the PVN seems to be mediated by stimulation of cannabinoid release.

Alternative explanations for rising dissolved organic carbon export from organic soils

Since 1988, there has been, on average, a 91% increase in dissolved organic carbon (DOC) concentrations of UK lakes and streams in the Acid Waters Monitoring Network (AWMN). Similar DOC increases have been observed in surface waters across much of Europe and North America. Much of the debate about the causes of rising DOC has, as in other studies relating to the carbon cycle, focused on factors related to climate change. Data from our peat-core experiments support an influence of climate on DOC, notably an increase in production with temperature under aerobic, and to a lesser extent anaerobic, conditions. However, we argue that climatic factors may not be the dominant drivers of DOC change. DOC solubility is suppressed by high soil water acidity and ionic strength, both of which have decreased as a result of declining sulphur deposition since the 1980s, augmented during the 1990s in the United Kingdom by a cyclical decline in sea-salt deposition. Our observational and experimental data demonstrate a clear, inverse and quantitatively important link between DOC and sulphate concentrations in soil solution. Statistical analysis of 11 AWMN lakes suggests that rising temperature, declining sulphur deposition and changing sea-salt loading can account for the majority of the observed DOC trend. This combination of evidence points to the changing chemical composition of atmospheric deposition, particularly the substantial reduction in anthropogenic sulphur emissions during the last 20 years, as a key cause of rising DOC. The implications of rising DOC export for the carbon cycle will be very different if linked primarily to decreasing acid deposition, rather than to changes in climate, suggesting that these systems may be recovering rather than destabilising.

Export of dissolved organic carbon from an upland peatland during storm events: implications for flux estimates

Most of the dissolved organic carbon (DOC) exported from catchments is transported during storm events. Accurate assessments of DOC fluxes are essential to understand long-term trends in the transport of DOC from terrestrial to aquatic systems, and also the loss of carbon from peatlands to determine changes in the source/sink status of peatland carbon stores. However, many long-term monitoring programmes collect water samples at a frequency (e.g. weekly/monthly) less than the time period of a typical storm event (typically <1–2 days). As widespread observations in catchments dominated by organo-mineral soils have shown that both concentration and flux of DOC increases during storm events, lower frequency monitoring could result in substantial underestimation of DOC flux as the most dynamic periods of transport are missed. However, our intensive monitoring study in a UK upland peatland catchment showed a contrasting response to these previous studies. Our results showed that (i) DOC concentrations decreased during autumn storm events and showed a poor relationship with flow during other seasons; and that (ii) this decrease in concentrations during autumn storms caused DOC flux estimates based on weekly monitoring data to be over-estimated, rather than under-estimated, because of over rather than under estimation of the flow-weighted mean concentration used in flux calculations. However, as DOC flux is ultimately controlled by discharge volume, and therefore rainfall, and the magnitude of change in discharge was greater than the magnitude of decline in concentrations, DOC flux increased during individual storm events. The implications for long-term DOC trends are therefore contradictory, as increased rainfall could increase flux but cause an overall decrease in DOC concentrations from peatland streams. Care needs to be taken when interpreting long-term trends in DOC flux rather than concentration; as flux is calculated from discharge estimates, and discharge is controlled by rainfall, DOC flux and rainfall/discharge will always be well correlated.

Influence of drought-induced acidification on the mobility of dissolved organic carbon in peat soils

A strong relationship between dissolved organic carbon (DOC) and sulphate (SO42−) dynamics under drought conditions has been revealed from analysis of a 10-year time series (1993–2002). Soil solution from a blanket peat at 10 cm depth and stream water were collected at biweekly and weekly intervals, respectively, by the Environmental Change Network at Moor House-Upper Teesdale National Nature Reserve in the North Pennine uplands of Britain. DOC concentrations in soil solution and stream water were closely coupled, displaying a strong seasonal cycle with lowest concentrations in early spring and highest in late summer/early autumn. Soil solution DOC correlated strongly with seasonal variations in soil temperature at the same depth 4-weeks prior to sampling. Deviation from this relationship was seen, however, in years with significant water table drawdown (>−25 cm), such that DOC concentrations were up to 60% lower than expected. Periods of drought also resulted in the release of SO42−, because of the oxidation of inorganic/organic sulphur stored in the peat, which was accompanied by a decrease in pH and increase in ionic strength. As both pH and ionic strength are known to control the solubility of DOC, inclusion of a function to account for DOC suppression because of drought-induced acidification accounted for more of the variability of DOC in soil solution (R2=0.81) than temperature alone (R2=0.58). This statistical model of peat soil solution DOC at 10 cm depth was extended to reproduce 74% of the variation in stream DOC over this period. Analysis of annual budgets showed that the soil was the main source of SO42− during droughts, while atmospheric deposition was the main source in other years. Mass balance calculations also showed that most of the DOC originated from the peat. The DOC flux was also lower in the drought years of 1994 and 1995, reflecting low DOC concentrations in soil and stream water. The analysis presented in this paper suggests that lower concentrations of DOC in both soil and stream waters during drought years can be explained in terms of drought-induced acidification. As future climate change scenarios suggest an increase in the magnitude and frequency of drought events, these results imply potential for a related increase in DOC suppression by episodic acidification.

Carbon fractions associated with silt-size particles in surface and subsurface soil horizons

Information on the distribution and behavior of C fractions in soil particle sizes is crucial for understanding C dynamics in soil. At present little is known about the behavior of the C associated with silt-size particles. We quantified the concentrations, distribution, and enrichment of total C (TC), readily oxidizable C (ROC), hotwater- extractable C (HWC), and cold-water-extractable C (CWC) fractions in coarse (63–20-mm), medium (20–6.3-mm), and fine (6.3–2-mm) silt-size subfractions and in coarse (2000–250 mm) and fine (250–63 mm) sand and clay (<2-mm) soil fractions isolated from bulk soil (<2 mm), and 2- to 4-mm aggregate-size fraction of surface (0–25 cm) and subsurface (25–55 cm) soils under different land uses. All measured C fractions varied significantly across all soil particle-size fractions. The highest C concentrations were associated with the <20-mm soil fractions and peaked in the medium (20–6.3-mm) and fine (6.3–2-mm) silt subfractions in most treatments. Carbon enrichment ratios (ERC) revealed the dual behavior of the C fractions associated with the medium silt-size fraction, demonstrating the simultaneous enrichment of TC and ROC, and the depletion of HWC and CWC fractions. The medium silt (20–6.3-mm) subfraction was identified in this study as a zone where the associated C fractions exhibit transitory qualities. Our results show that investigating subfractions within the silt-size particle fraction provides better understanding of the behavior of C fractions in this soil fraction.

The surface geometries of the medium and high coverage carbon monoxide structures c(2 × 4)–(2CO) and p(root7- x root7)R19°–(4CO) structure

The surface geometries of the p (root7- x root7)R19degrees-(4CO) and c(2 x 4)-(2CO) layers on Ni {111} and the clean Ni {111} surface were determined by low energy electron diffraction structure analysis. For the clean surface small but significant contractions of d(12) and d(23) (both 2.02 Angstrom) were found with respect to the bulk interlayer distance (2.03 Angstrom). In the c(2 x 4)-(2CO) structure these distances are expanded, with values of d(12) = 2.08 Angstrom and d(23) = 2.06 Angstrom and buckling of 0.08 and 0.02 Angstrom, respectively, in the first and second layer. CO resides near hcp and fcc hollow sites with relatively large lateral shifts away from the ideal positions leading to unequal C-Ni bond lengths between 1.76 and 1.99 Angstrom. For the p(root7- x root7-)R19'-(4CO) layer two best fit geometries were found, which agree in most of their atomic positions, except for one out of four CO molecules, which is either near atop or between bridge and atop. The remaining three molecules reside near hcp and fcc sites, again with large lateral deviations from their ideal positions. The average C Ni bond length for these molecules is, however, the same as for CO on hollow sites at low coverage. The average CNi bond length at hollow sites, the interlayer distances, and buckling in the first Ni layer are similar to the c(2 x 4)(2CO) geometry, only the buckling in the second layer (0.08 Angstrom) is significantly larger. Lateral and vertical shifts of the Ni atoms in the first layer lead to unsymmetric environments for the CO molecules, which can be regarded as an imprint of the chiral p(root7- x root7-)R19degrees lattice geometry onto the substrate.

The surface geometry of carbon monoxide and oxygen co-adsorbed on Ni{111}

Low energy electron diffraction (LEED) structure determinations have been performed for the p(2 x 2) structures of pure oxygen and oxygen co-adsorbed with CO on Ni{111}. Optimisation of the non-geometric parameters led to very good agreement between experimental and theoretical IV-curves and hence to a high accuracy in the structural parameters. In agreement with earlier work atomic oxygen is found to adsorb on fee sites in both structures. In the co-adsorbed phase CO occupies atop sites. The positions of the substrate atoms are almost identical, within 0.02 Angstrom, in both structures, implying that the interaction with oxygen dominates the arrangement of Ni atoms at the surface.

Seasonally resolved growth of freshwater bivalves determined by oxygen and carbon isotope shell chemistry

By means of a monitoring experiment in two rivers in the Netherlands, we establish a relationship between seasonally resolved growth rates in unionid freshwater bivalves and their environment. We reconstructed these seasonally resolved growth rates by using relationships of stable isotopes in the shells and their ambient river water. The reconstructed growth rates reveal that shells grow fastest in spring-early summer, when highest food availability occurs in the rivers. In addition, the reconstructed growth rates show that onset and cessation of growth are mainly influenced by water temperature.