464 research outputs found
Promiscuous, non-catalytic, tandem carbohydrate-binding modules modulate the cell-wall structure and development of transgenic tobacco (Nicotiana tabacum) plants
We have compared heterologous expression of
two types of carbohydrate binding module (CBM) in tobacco
cell walls. These are the promiscuous CBM29
modules (a tandem CBM29-1-2 and its single derivative
CBM29-2), derived from a non-catalytic protein1, NCP1,
of the Piromyces equi cellulase/hemicellulase complex,
and the less promiscuous tandem CBM2b-1-2 from the
Cellulomonas fimi xylanase 11A. CBM-labelling studies
revealed that CBM29-1-2 binds indiscriminately to every
tissue of the wild-type tobacco stem whereas binding of
CBM2b-1-2 was restricted to vascular tissue. The promiscuous
CBM29-1-2 had much more pronounced effects on
transgenic tobacco plants than the less promiscuous
CBM2b-1-2. Reduced stem elongation and prolonged
juvenility, resulting in delayed flower development, were
observed in transformants expressing CBM29-1-2 whereas
such growth phenotypes were not observed for CBM2b-1-2
plants. Histological examination and electron microscopy
revealed layers of collapsed cortical cells in the stems of
CBM29-1-2 plants whereas cellular deformation in the
stem cortical cells of CBM2b-1-2 transformants was less
severe. Altered cell expansion was also observed in most
parts of the CBM29-1-2 stem whereas for the CBM2b-1-2
stem this was observed in the xylem cells only. The cellulose
content of the transgenic plants was not altered.
These results support the hypothesis that CBMs can modify
cell wall structure leading to modulation of wall loosening
and plant growth
The ethanolamide metabolite of DHA, docosahexaenoylethanolamine, shows immunomodulating effects in mouse peritoneal and RAW264.7 macrophages: evidence for a new link between fish oil and inflammation
Several mechanisms have been proposed for the positive health effects associated with dietary consumption of long-chain n-3 PUFA (n-3 LC-PUFA) including DHA (22 : 6n-3) and EPA (20 : 5n-3). After dietary intake, LC-PUFA are incorporated into membranes and can be converted to their corresponding N-acylethanolamines (NAE). However, little is known on the biological role of these metabolites. In the present study, we tested a series of unsaturated NAE on the lipopolysaccharide (LPS)-induced NO production in RAW264.7 macrophages. Among the compounds tested, docosahexaenoylethanolamine (DHEA), the ethanolamide of DHA, was found to be the most potent inhibitor, inducing a dose-dependent inhibition of NO release. Immune-modulating properties of DHEA were further studied in the same cell line, demonstrating that DHEA significantly suppressed the production of monocyte chemotactic protein-1 (MCP-1), a cytokine playing a pivotal role in chronic inflammation. In LPS-stimulated mouse peritoneal macrophages, DHEA also reduced MCP-1 and NO production. Furthermore, inhibition was also found to take place at a transcriptional level, as gene expression of MCP-1 and inducible NO synthase was inhibited by DHEA. To summarise, in the present study, we showed that DHEA, a DHA-derived NAE metabolite, modulates inflammation by reducing MCP-1 and NO production and expression. These results provide new leads in molecular mechanisms by which DHA can modulate inflammatory processes
Unravelling discolouration caused by iron-flavonoid interactions:Complexation, oxidation, and formation of networks
Expression of an expansin carbohydrate-binding module affects xylem and phloem formation
Expansins are believed to be involved in disrupting the non-covalent adhesion of cellulose to matrix polysaccharides, thereby promoting wall creep. We have targeted a putative potato expansin (EXPA)carbohydrate-binding module (CBM) to the cell walls of tobacco plants. Histological examinations and electron microscopy indicated that 30% of the xylem cells of the transgenic stems with high expressionof the expansin CBM are wider (radial surface area) than those of the controls. Similarly, 37% of the xylem cells of the stems of the high expressers have thinner cell walls than those of the controls. Therewere no such phenotypes in the low and none expressers, as well as in the control plants. The transgenic tobacco plants expressing the potato expansin CBM did not exhibit marked change in plant morphology. Analysis of cellulose content in the stem cell walls was similar between the high expresser of the transgene and the control plants. Nonetheless, our results taken together demonstrate that expansin CBM alone can bring about changes in the plant cell walls
Interactions of Natural Flavones with Iron Are Affected by 7-O-Glycosylation, but Not by Additional 6″-<i>O</i>-Acylation
In iron-fortified bouillon, reactivity of the iron ion with (acylated) flavone glycosides from herbs can affect product color and bioavailability of iron. This study investigates the influence of 7-O-glycosylation and additional 6″-O-acetylation or 6″-O-malonylation of flavones on their interaction with iron. Nine (6″-O-acylated) flavone 7-O-apiosylglucosides were purified from celery (Apium graveolens), and their structures were elucidated by mass spectrometry (MS) and nuclear magnetic resonance (NMR). In the presence of iron, a bathochromic shift and darker color were observed for the 7-O-apiosylglucosides compared to the aglycon of flavones that only possess the 4-5 site. Thus, the ability of iron to coordinate to the flavone 4-5 site is increased by 7-O-glycosylation. For flavones with an additional 3′-4′ site, less discoloration was observed for the 7-O-apiosylglucoside compared to the aglycon. Additional 6″-O-acylation did not affect the color. These findings indicate that model systems used to study discoloration in iron-fortified foods should also comprise (acylated) glycosides of flavonoids.</p
Interaction of iron(III) with taste enhancers:Potential of Fe(III) salts with inosine monophosphate or guanosine monophosphate for food fortification
Iron interactions in iron-fortified savory concentrates lead to undesirable discoloration, even when poorly-water soluble iron salts such as ferric pyrophosphate (Fe4PP3) are used. This is the first study to comprehensively investigate the interaction of Fe(III) with three common taste enhancers: glutamate (Glu), inosine monophosphate (IMP), and guanosine monophosphate (GMP). The stability of the complexes of Fe(III) with IMP or GMP is higher compared to that with Glu. Neutrality of IMP or GMP species with Fe(III) at pH 3–8 resulted in precipitation. This property was exploited to synthesize Fe(III) salts of IMP or GMP (i.e. Fe2IMP3 and Fe2GMP3) by aqueous chemical precipitation. Iron dissolution from Fe2IMP3 and Fe2GMP3 was up to twenty-fold higher at gastric pH (1–3), indicative of better bio-accessibility, and up to fifteen-fold lower at food pH (3–7), indicative of decreased reactivity in food, compared to Fe4PP3. Consequently, Fe2IMP3 and Fe2GMP3, compared to Fe4PP3, led to less discoloration in combination with the poorly soluble phenolics that are commonly present in savory concentrates. We conclude that Fe(III) salts of IMP or GMP can potentially serve as iron fortificants due to their increased solubility at gastric pH (1–3), decreased iron dissolution at food pH (3–7), and decreased reactivity at food pH.</p
Reactivity of Fe(III)-containing pyrophosphate salts with phenolics: complexation, oxidation, and surface interaction
A comprehensive two-dimensional liquid chromatography method for the simultaneous separation of lipid species and their oxidation products
Design and characterization of Ca-Fe(III) pyrophosphate salts with tunable pH-dependent solubility for dual-fortification of foods
Pelvic Rotation and Tilt Can Cause Misinterpretation of the Acetabular Index Measured on Radiographs
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