Effects of cultural system (organic and conventional) on growth, photosynthesis and yield components of sweet corn (zea mays L.) under semi-arid environment

Organic sweet maize consists of a new industrial crop product. Field experiment was conducted to determine the effects of cultural systems on growth, photosynthesis and yield components of sweet maize crop (Zea mays L. F-1 hybrid 'Midas'). A randomized complete block design was employed with four replicates per treatment (organic fertilization: cow manure (5, 10 and 20 t ha(-1)), poultry manure (5, 10 and 20 t ha(-1)) and barley mulch (5, 10 and 20 t ha(-1)), synthetic fertilizer (240 kg N ha(-1)): 21-0-0 and control). The lowest dry weight, height and leaf area index and sod organic matter were measured in the control treatment. Organic matter content was proportionate to the amount of manure applied. The control plots had the lowest yield (1593 kg ha(-1)) and the double rate cow manure plots the had,greatest one. (6104 kg ha(-1)). High correlation between sweet corn yield and organic matter was registered. Moreover, the lowest values of 1000-grain weight were obtained with control plot. The fertilizer plot gave values which were similar to the full rate cow manure treatment. The photosynthetic race of the untreated control was significantly lower than that of the other treatments. The phorosynthetic rate increased as poultry manure and barley mulch ram decreased and as cow manure increased. Furthermore the untreated control had the lowest stomatal conductance and chlorophyll content. Our results indicated that sweet corn growth and yield in the organic plots was significantly higher than those in the conventional plots.

Electrochemical determination of plant-derived leuco-indigo after chemical reduction by glucose

Electrochemical determination of redox active dye species is demonstrated in indigo samples contaminated with high levels of organic and inorganic impurities. The use of a hydrodynamic electrode system based on a vibrating probe (250 Hz, 200 mu m lateral amplitude) allows time-independent diffusion controlled signals to be enhanced and reliable concentration data to be obtained under steady state conditions at relatively fast scan rates up to 4 V s-1In this work the indigo content of a complex plant-derived indigo sample (dye content typically 30%) is determined after indigo is reduced by addition of glucose in aqueous 0.2 M NaOH. The soluble leuco-indigo is measured by its oxidation response at a vibrating electrode. The vibrating electrode, which consisted of a laterally vibrating 500 mu m diameter gold disc, is calibrated with Fe(CN)(6) 3-/4- in 0.1 M KCl and employed for indigo determination at 55, 65, and 75 C in 0.2 M NaOH. Determinations of the indigo content of 25 different samples of plant-derived indigo are compared with those obtained by conventional spectrophotometry. This comparison suggests a significant improvement by the electrochemical method, which appears to be less sensitive to impurities.

Prebiotics and bowel cancer

Bowel cancer is a growing malignancy, with more than a million annual cases reported worldwide. It has been suggested that there is microbial involvement in onset of the disease and that an altered composition has previously been observed in those suffering from the malignancy, compared to healthy counterparts. The use of prebiotic functional foods to modify the colonic microflora may provide a method of reducing genotoxic potential within the colon, whilst offering-Protective strategies in the form of metabolites such as butyrate. The following review highlights some of the studies that demonstrate the potentia role for prebiotics as protective factors against bowel cancer.

Studying the Human Gut Microbiota in the Trans-Omics Era - Focus on Metagenomics and Metabonomics

The human gut microbiota comprises a diverse microbial consortium closely co-evolved with the human genome and diet. The importance of the gut microbiota in regulating human health and disease has however been largely overlooked due to the inaccessibility of the intestinal habitat, the complexity of the gut microbiota itself and the fact that many of its members resist cultivation and are in fact new to science. However, with the emergence of 16S rRNA molecular tools and "post-genomics" high resolution technologies for examining microorganisms as they occur in nature without the need for prior laboratory culture, this limited view of the gut microbiota is rapidly changing. This review will discuss the application of molecular microbiological tools to study the human gut microbiota in a culture independent manner. Genomics or metagenomics approaches have a tremendous capability to generate compositional data and to measure the metabolic potential encoded by the combined genomes of the gut microbiota. Another post-genomics approach, metabonomics, has the capacity to measure the metabolic kinetic or flux of metabolites through an ecosystem at a particular point in time or over a time course. Metabonomics thus derives data on the function of the gut microbiota in situ and how it responds to different environmental stimuli e.g. substrates like prebiotics, antibiotics and other drugs and in response to disease. Recently these two culture independent, high resolution approaches have been combined into a single "transgenomic" approach which allows correlation of changes in metabolite profiles within human biofluids with microbiota compositional metagenomic data. Such approaches are providing novel insight into the composition, function and evolution of our gut microbiota.

The effect of nicotine in vitro on the integrity of tight junctions in Caco-2 cell monolayers

Ulcerative colitis is characterised by impairment of the epithelial barrier and tight junction alterations resulting in increased intestinal permeability. UC is less common in smokers with smoking reported to decrease paracellular permeability. The aim of this study was thus to determine the effect of nicotine, the major constituent in cigarettes and its metabolites on the integrity of tight junctions in Caco-2 cell monolayers. The integrity of Caco-2 tight junctions was analysed by measuring the transepithelial electrical resistance (TER) and by tracing the flux of the fluorescent marker fluorescein, after treatment with various concentrations of nicotine or nicotine metabolites over 48 h. TER was significantly higher compared to the control for all concentrations of nicotine 0.01-10 M at 48 h (p < 0.001), and for 0.01 mu M (p < 0.001) and 0.1 mu M and 10 M nicotine (p < 0.01) at 12 and 24 h. The fluorescein flux results supported those of the TER assay. TER readings for all nicotine metabolites tested were also higher at 24 and 48 h only (p <= 0.01). Western blot analysis demonstrated that nicotine up-regulated the expression of the tight junction proteins occludin and claudin-l (p < 0.01). Overall, it appears that nicotine and its metabolites, at concentrations corresponding to those reported in the blood of smokers, can significantly improve tight junction integrity, and thus, decrease epithelial gut permeability. We have shown that in vitro, nicotine appears more potent than its metabolites in decreasing epithelial gut permeability. We speculate that this enhanced gut barrier may be the result of increased expression of claudin-l and occludin proteins, which are associated with the formation of tight junctions. These findings may help explain the mechanism of action of nicotine treatment and indeed smoking in reducing epithelial gut permeability. (c) 2007 Elsevier Ltd. All rights reserved.

A double-blind, placebo controlled human study investigating the effects of coffee derived manno-oligosaccharides on the faecal microbiota of a healthy adult population.

The aims of this study were to assess the impact of coffee derived mannooligosaccharides on the faecal microbiota of a healthy UK based population. Methods and Results: A double-blind, placebo-controlled, crossover human intervention study was conducted. Volunteers were assigned, 3g MOS, 5g MOS and placebo coffee preparations, to consume daily over a 3 wks, followed by a 2 wk washout period. Faecal samples were collected, and microbial population characterised using fluorescence in situ hybridization. Short-chain and branched-chain fatty acid profiles were obtained by gas chromatography. All treatments led to significant lactobacilli increases (placebo, p < 0.001; 3g, p = 0.04; 5g, p=0.04). The 3g treatment led to a significant bifidobacteria increase (p=0.001). Significantly less iso-valerate was found in faeces following 3g MOS daily (p=0.05). Conclusions: The 3g dose of MOS led to a potentially beneficial shift in the faecal microbiota. MOS was therefore confirmed to be a prebiotic at 3g dose. Significance and Impact of Study: This study provides confirmation of a new novel prebiotic, that can be considered for incorporation into a wider variety of food products, to provide different selective and nutritional properties.

Prebiotics and probiotics: potential strategies for reducing travellers' diarrhoea in athletes competing abroad

Travellers’ diarrhoea (TD) is the most common gastrointestinal illness to affect athletes competing abroad. Consequences of this debilitating condition include difficulties with training and/or participating in competitions which the athlete may have spent several years preparing for. Currently, there are no targeted strategies to reduce TD incidence in athletes. General methods used to reduce TD risk, such as avoidance of contaminated foods, chemoprophylactics and immunoprophylactics, have disadvantages. Since most causative agents of TD are microbial, strategies to minimise TD risks may be better focused on the gut microbiota. Prebiotics and probiotics can fortify the gut microbial balance, thus potentially aiding the fight against TD-associated microorganisms. Specific probiotics have shown promising actions against TD-associated microorganisms through antimicrobial activities. Use of prebiotics has led to an improved intestinal microbial balance which may be better equipped to combat TD-associated microorganisms. Both approaches have shown promising results in general travelling populations; therefore, a targeted approach for athletes has the potential to provide a competitive advantage.