Pectin does not inhibit intestinal carcinogenesis in APC-deficient Min/+ mice     

Jacobasch G  Dongowski G  Florian S  Müller-Schmehl K  Raab B  Schmiedl D 《Journal of agricultural and food chemistry》2008,56(4):1501-1510

APC-germline mutation creates predisposition for intestinal tumorigenesis. APCMin/+ mice, developing tumors preferentially in the small intestine and only minimally in the colon, were fed pectin-enriched diets (10% galacturonan; degree of methoxylation=37.0 and 70.4%) or standard diet. Pectins used in the present study do not inhibit intestinal tumorigenesis and rather accelerate it in APCMin/+ mice. Both pectins exhibited prebiotic effects associated with high fermentative formation of acetate but producing low butyrate. The differences of the short-chain fatty acid concentrations between cecum and colon and those between colon and feces were larger than expected and increased with cancer progression, indicating an inhibition of butyrate absorption. Pectins transported more bile acids toward the colon than the standard diet and caused a higher generation of secondary bile acids despite lower pH values. Overexpression of COX-2 resulted in lower antioxidative capacity, thus promoting cancer. Apoptosis increased in hyperplasia but decreased in late adenomas. When biological modular design principles are taken into consideration, it can be expected that pectin also reinforces colorectal tumorigenesis of patients suffering from APC gene defects.  相似文献   

Genotoxicity of glycidamide in comparison to 3-N-nitroso-oxazolidin-2-one     

Baum M  Loeppky RN  Thielen S  Eisenbrand G 《Journal of agricultural and food chemistry》2008,56(15):5989-5993

Acrylamide (AA) is generated by thermal processing of foods, depending on processing conditions and precursor availability. AA is not genotoxic by itself but becomes activated to its genotoxic metabolite glycidamide (GA) via epoxidation, mediated primarily by cytochrome P450 2E1. In the Comet assay in V79 cells and in human lymphocytes, GA induced DNA damage down to 300 microM concentration (4 h). After post-treatment with the DNA repair enzyme formamidopyrimidine-DNA-glycosylase (FPG), DNA damage became already detectable at 10 microM (4 h). By comparison, the N-nitroso compound 3- N-nitroso-oxazolidin-2-one (NOZ-2) is a much stronger genotoxic agent, significantly inducing DNA damage already at 15 min (3 microM). Post-treatment with FPG in this case did not enhance response. GA induced DNA damage in V79 cells rather slowly, with first response detectable at 4 h. The hPRT forward mutation test encompasses 5 days of expression time during which also repair can take place. GA-induced hPRT mutations only became detectable at concentrations of 800 microM and above. This is 80-fold higher than the lowest significant response to GA in the Comet assay (10 microM with FPG). In contrast, NOZ-2 was as effective in the hPRT test as in the Comet assay (3 microM). These results demonstrate substantial differences in the genotoxic potency of GA and NOZ-2. Whereas NOZ-2 is a pontent genotoxic mutagen, GA in comparison shows only low genotoxic and mutagenic potential, presumably as a result, at least in part, of preferential N7-G alkylation.  相似文献   

Cellular uptake of carotenoid-loaded oil-in-water emulsions in colon carcinoma cells in vitro     

Ribeiro HS  Guerrero JM  Briviba K  Rechkemmer G  Schuchmann HP  Schubert H 《Journal of agricultural and food chemistry》2006,54(25):9366-9369

Oil-in-water emulsions allow the preparation of lipophilic compounds such as carotenoids in the liquid form. Here, the effect of a combination of some emulsifiers, such as two whey protein isolates (BiPro and BioZate), sucrose laurate (L-1695), and polyoxyethylene-20-sorbitan-monolaurate (Tween 20), on the stability of lycopene and astaxanthin in emulsions, droplet size, and cellular uptake of these carotenoids has been investigated. The degradation of lycopene was slightly more pronounced than that of astaxanthin in all emulsions. The concentration of lycopene and astaxanthin decreased by about 30% and 20%, respectively, in all emulsions after 3 weeks of storage in the dark at 4 degrees C. The kind of emulsifiers or their combinations have played an important role in the cellular uptake by the colon carcinoma cells line HT-29 and Caco-2.  相似文献   

Chemical composition and antioxidant properties of clove leaf essential oil     

Jirovetz L  Buchbauer G  Stoilova I  Stoyanova A  Krastanov A  Schmidt E 《Journal of agricultural and food chemistry》2006,54(17):6303-6307

The antioxidant activity of a commercial rectified clove leaf essential oil (Eugenia caryophyllus) and its main constituent eugenol was tested. This essential oil comprises in total 23 identified constituents, among them eugenol (76.8%), followed by beta-caryophyllene (17.4%), alpha-humulene (2.1%), and eugenyl acetate (1.2%) as the main components. The essential oil from clove demonstrated scavenging activity against the 2,2-diphenyl-1-picryl hydracyl (DPPH) radical at concentrations lower than the concentrations of eugenol, butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA). This essential oil also showed a significant inhibitory effect against hydroxyl radicals and acted as an iron chelator. With respect to the lipid peroxidation, the inhibitory activity of clove oil determined using a linoleic acid emulsion system indicated a higher antioxidant activity than the standard BHT.  相似文献   

Escherichia coli induces DNA double-strand breaks in eukaryotic cells     

Nougayrède JP  Homburg S  Taieb F  Boury M  Brzuszkiewicz E  Gottschalk G  Buchrieser C  Hacker J  Dobrindt U  Oswald E 《Science (New York, N.Y.)》2006,313(5788):848-851

Transient infection of eukaryotic cells with commensal and extraintestinal pathogenic Escherichia coli of phylogenetic group B2 blocks mitosis and induces megalocytosis. This trait is linked to a widely spread genomic island that encodes giant modular nonribosomal peptide and polyketide synthases. Contact with E. coli expressing this gene cluster causes DNA double-strand breaks and activation of the DNA damage checkpoint pathway, leading to cell cycle arrest and eventually to cell death. Discovery of hybrid peptide-polyketide genotoxins in E. coli will change our view on pathogenesis and commensalism and open new biotechnological applications.  相似文献   

Analytic and quality control validation and assessment of field performance of a point‐of‐care chemistry analyzer for use in the White rhinoceros          下载免费PDF全文

Emma H. Hooijberg  Gerhard Steenkamp  Jacques P. du Preez  Amelia Goddard 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2017,46(1):100-110

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Quantitative trait loci mapping of forage stover quality traits in six mapping populations derived from European elite maize germplasm          下载免费PDF全文

Pengfei Leng  Milena Ouzunova  Matthias Landbeck  Gerhard Wenzel  Joachim Eder  Birte Darnhofer  Thomas Lübberstedt 《Plant Breeding》2018,137(2):139-147

Four forage maize stover quality traits were analysed including in vitro digestibility of organic matter (IVDOM), neutral detergent fibre (NDF), water‐soluble carbohydrates (WSC) and digestibility of NDF (DNDF). We mapped quantitative trait loci (QTL) in three DH (doubled haploid) populations (totally 250–720 DH lines): one RIL population (358 lines) and two testcross (TC) populations, based on field phenotyping at multiple locations and years for each. High phenotypic and genotypic correlations were found for all traits and significant (p < .01) at two locations, and NDF was negatively correlated with the other traits. QTL analyses were conducted by composite interval mapping. A total of 33, 23, 32 and 25 QTL were identified for IVDOM, NDF, WSC and DNDF, respectively, with three, four, five and two major QTL for each. Few consistent QTL for IVDOM, WSC and DNDF were detected in more than two populations. This study contributed to the identification of key QTL associated with forage maize digestibility traits and is beneficial for marker‐assisted breeding and fine mapping of candidate genes associated with forage maize quality.  相似文献   

Rubber intercropping: a viable concept for the 21st century?     

Gerhard Langenberger  Georg Cadisch  Konrad Martin  Shi Min  Hermann Waibel 《Agroforestry Systems》2017,91(3):577-596

The last decades brought along a tremendous expansion of rubber plantations as well as respective socio-economic transformations. This paper reviews the historical development of rubber cultivation with special reference to intercropping and illustrates the major development steps. The agronomic challenges of intercropping are analyzed and a management classification scheme is suggested. Though the topic of labor always accompanied rubber management, it is nowadays of even higher relevance due to alternative income options, be it due to competing crops such as oil palm, or be it off-farm income opportunities. This development challenges labor intensive permanent intercropping systems. It can thus be concluded that the permanent integration of additional plants needs either to be highly profitable or at least be labor extensive to be adopted on a considerable scale. Given the large area of rubber plantations the latter seems to be more realistic. In this context timber trees might offer promising options if tree selection is properly adapted to site and plantation conditions. Nevertheless, without external interventions, such as land-use planning and implementation, or incentives, the development will be difficult to control.  相似文献   

耕地土壤有机碳组分的季节变化     

Henning SCHIEDUNG  Ludger BORNEMANN  Gerhard WELP 《土壤圈》2017,27(2):380-386

Carbon fractions in soils apparently vary not only in space, but also over time. A lack of knowledge on the seasonal variability of labile carbon fractions under arable land hampers the reliability and comparability of soil organic carbon(SOC) surveys from different studies. Therefore, we studied the seasonal variability of two SOC fractions, particulate organic matter(POM) and dissolved organic carbon(DOC), under maize cropping: POM was determined as the SOC content in particle-size fractions, and DOC was measured as the water-extractable SOC(WESOC) of air-dried soil. Ammonium, nitrate, and water-extractable nitrogen were measured as potential regulating factors of WESOC formation because carbon and nitrogen cycles in soils are strongly connected. There was a significant annual variation of WESOC(coefficient of variation(CV) = 30%). Temporal variations of SOC in particle-size fractions were smaller than those of WESOC. The stocks of SOC in particle-size fractions decreased with decreasing particle sizes, exhibiting a CV of 20%for the coarse sand-size fraction(250–2 000 μm), of 9% for the fine sand-size fraction(50–250 μm), and of 5% for the silt-size fraction(20–50 μm). The WESOC and SOC in particle-size fractions both peaked in March and reached the minimum in May/June and August, respectively. These results indicate the importance of the time of soil sampling during the course of a year, especially when investigating WESOC.  相似文献