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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

The effect of lipo-chitooligosaccharide from Bradyrhizobium japonicum, on soybean salicylic acid, pathogenesis-related protein activity and gene expression /

Lindsay, John Keldeagh. January 2007 (has links)
In this study, lipo-chitooligosaccharide (NodBj-V (C 18:1, MeFuc); LCO) 10-7M, extracted from Bradyrhizobium japonicum, was sprayed on the leaves of soybean cv. OAC Bayfield soybean and Evans x L66-2470 (carrying the rj1 mutation, and unable to nodulate). Leaf SA level and activities of the PR proteins chitinase, beta-1,3-glucanase and guaiacol peroxidase (GPOX) were quantified. Phenylalanine ammonia-lyase 1 (PAL1) and isoflavone synthase 2 (IFS2) relative gene expression levels in the sprayed leaves were quantified using quantitative real-time PCR. Messenger RNA abundance was quantified using microarrays. The treatment caused a transient increase in local salicylate levels 24 h after exposure, and a systemic increase in GPOX activity 48 h after exposure, in both soybean types. Of the selected 38 genes affected by the LCO treatment, 25 were stress-related. There were no significant differences in (A) chitinase and beta-1,3-glucanase activity, or (B) in PAL1 and IFS2 gene expression.
112

Evaluation of purified lignin and mannanoligosaccharides as alternatives to antibiotic growth promoters in poultry production

Baurhoo, Bushansingh. January 2007 (has links)
The potential of lignin and mannanoligosaccharides (MOS), as alternatives to antibiotic growth promoters was evaluated in broilers. Dietary treatments included: (1) negative control (CTL-, antibiotic free); (2) positive control (CTL+, 11 mg/kg virginiamycin); (3) MOS (diet 1 + Bio-Mos: 0.2% to 21 d and 0.1% thereafter); (4) LL (diet 1 + 1.25% Alcell lignin); (5) HL (diet 1 + 2.5% Alcell lignin). Bodyweight and feed conversion were not different when broilers were fed the CTL+, MOS, LL or HL diet. Birds fed MOS or LL had increased jejunum villi height (P < 0.05) and greater goblet cell number per villus (P < 0.05) when compared to those fed the CTL+ diet. MOS and LL increased (P < 0.05) the cecal populations of Lactobacilli and Bifidobacteria when compared to CTL+ fed birds. However, Lactobacilli and Bifidobacteria loads were lowest (P < 0.05) in birds fed the CTL+ or HL diet. Litter E. coli load was reduced (P < 0.05) when birds were fed MOS than when fed the CTL+ diet, but comparable to LL or HL fed birds. In birds challenged with pathogenic strains of E. coli (O2 and O88 serotypes) and fed the MOS or HL diet, the cecal population of total E. coli was lower (P < 0.05) than those fed the CTL+ diet; LL fed birds tended to have lower E. coli load than CTL+ fed birds. In summary, birds fed the MOS or LL diet had comparative advantage over CTL+ fed birds as evidenced by increased cecal populations of Lactobacilli and Bifdobacteria, increased villi height and greater goblet cell number in the jejunum, lower E. coli load in the litter, and lower cecal population of E. coli after an in vivo challenge with pathogenic strains of E. coli. Therefore, MOS and lignin could be regarded as natural alternatives to antibiotic growth promoters in poultry production. / Key words. Antibiotics, mannanoligosaccharides, lignin, gut health, broilers.
113

Microbial influence on intestinal development and mode of action of mannan oligosaccharides in broiler chicken

2015 October 1900 (has links)
The effect of intestinal microbiota and dietary supplementation of mannan oligosaccharides (MOS) on mucosal architecture and digestive physiology in broiler chicks was examined. In experiment 1, pre-sterilized eggs (Ross x Ross 308) were placed in three HEPA (high efficiency particulate air)-filtered isolator units at day 19 of incubation. Germ-free chicks in one isolator were conventionalized by exposure to cecal contents from a laying hen. Bacterial contamination occurred in one germ-free isolator such that these birds were monoassociated by a bacterium within the Acinetobacter spp. resulting in 3 categories of microbial status including germ-free (GF, n=10), conventionalized (CV, n=19) and monoassociated (Mono, n=13) birds. Dietary treatments assigned to each isolator consisted of a negative control (NC, 0 g/kg of MOS in the basal diet) and MOS (2 g/kg of MOS in the diet) resulting in a 2X3 factorial treatment arrangement. At 7 d of age, body weight was recorded and birds were killed to permit collection of visceral organs, intestinal tissues and cecal contents. Body weight, relative length of small intestinal segments and relative bursa weight were significantly increased in CV birds. These birds also had increased crypt depth and lamina propria area. Dietary MOS increased villus height and villus surface area in CV birds compared with GF and Mono birds. Transcripts for all housekeeping genes tested in ileal tissue were increased by MOS such that transcripts were normalized to unit mass of total RNA. In comparison to birds fed the NC diet, MOS significantly increased the abundance of proliferative cell nuclear antigen (PCNA), toll-like receptor (TLR)-4, avian β-defensin (GAL)-6, interleukin (IL)-8, peptide transporter 1 (PepT1) and sodium-dependent glucose transporter (SGLT)-1 transcripts in ileum per unit total RNA. However, the effect of microbial status on selected gene expression profiles was surprisingly limited. A second experiment was conducted to confirm the conventionalization protocol produced a complex microbiota similar to conventionally reared birds. Twenty day-old broiler chicks (Ross x Ross 308) were assigned to one of two wire-floored battery cages provided the NC and MOS diets ad libitum and killed at 7 d of age. Terminal restriction fragment length polymorphism (TRFLP) analysis demonstrated that microbial diversity indices (Richness, Evenness, Shannon, and Simpson) were greater in conventionalized gnotobiotic birds compared to the conventionally reared birds confirming a successful conventionalization strategy in the gnotobiotic trial. These studies demonstrate that under good hygienic conditions, CV chicks thrive similar to GF animals. Based on responses to MOS observed in GF birds, evidence indicates that MOS, independent of changes in microbial composition, directly modifies host response parameters including innate immune activation, digestive and absorptive function.
114

Pretreatment and enzyme hydrolysis of canola meal (Brassica napus L.) and oriental mustard bran (Brassica juncea): production of functional oligosaccharides and impact on phenolic content

Yuan, Lin 19 April 2014 (has links)
Canola meal (Brassica napus L.) and oriental mustard bran (Brassica juncea) were subjected to alkali and acid pretreatment to expose pentosan, for enhancing further enzymatic hydrolysis by endo-1,4-β-xylanase from Trichoderma longibrachiatum for the production of oligosaccharides. Pretreatment especially with alkali, effectively increased the relative content of pentosan to about ~ 41% and ~ 72%. Alkali pretreated canola meal and mustard bran resulted in a pentose content of 2.28 ± 0.15 g and 3.20 ± 0.11 g per 100 g substrates at 18 h and 24 h of reaction respectively, which corresponded to ~ 26% and ~ 28% conversion of original pentosan in substrates. UPLC-MS data showed xyloglucuronic acid (XGlcA) as the major oligosaccharide in the hydrolyzates. Reversed-phase HPLC-DAD indicated the principal phenolic compound in the hydrolyzates was sinapine. DPPH radical scavenging assay showed that endoxylananse hydrolyzates of acid pretreated substrates had strong antioxidant activities in comparison to alkali pretreated samples.
115

Synthèse d'oligosaccharides de chondroïtines et de sulfates de chondroïtines biotinylés pour l'étude de la biosynthèse des protéoglycanes du cartilage

Vibert, Aude 30 November 2009 (has links) (PDF)
L'arthrose est la plus fréquente des maladies articulaires pour laquelle aucun traitement efficace n'est aujourd'hui disponible. Elle est caractérisée par une destruction du cartilage et de ses composants, dont font partie les protéoglycanes. Les principaux protéoglycanes cartilagineux sont les sulfates de chondroïtines, qui sont de longs polysaccharides linéaires hétérogènes composés d'unités disaccharidiques répétitives constituées d'un acide-D-glucuronique et d'une N-acétyl-D-galactosamine. Dans le but d'étudier la biosynthèse de ces composés et ainsi de mieux comprendre le mécanisme d'action des enzymes qui y sont impliquées, la synthèse chimique d'oligosaccharides de chondroïtines et de sulfates de chondroïtines biotinylés a été réalisée. Grâce à une méthodologie efficace et innovante basée sur une hydrolyse acide d'un polymère de sulfates de chondroïtines, des intermédiaires clés ont rapidement été obtenus. Une stratégie d'élongation les utilisant a ensuite été appliquée pour conduire à une première famille de sept oligosaccharides non sulfatés (du disaccharide à l'octasaccharide). Deux nouvelles familles d'oligosaccharides de sulfates de chondroïtines A et C, sulfatés de façon homogène ont été préparées, à partir d'un précurseur commun par stratégie divergente. Pour la première fois, deux oligosaccharides de sulfate de chondroïtine A, présentant une sulfatation hétérogène, ont également été synthétisés. Ces travaux ont mené à la préparation de treize oligosaccharides biotinylés finaux.
116

Structural studies on oligosaccharides from mammalian glycoproteins

Field, Mark C. January 1989 (has links)
No description available.
117

Assessment of soybean (Glycine max (L.) Merr.) water stress : lipo-chitooligosaccharides application and spectral response

Atti, Sarra January 2002 (has links)
This study was conducted to improve knowledge of the impact of chronic soil water deficit and to test a novel technique of water management consisting of Lipo-chitooligosaccharides (LCO) spray application. It also aimed at evaluating changes in canopy reflectance due to water stress and LCO spray. Water stress during reproductive development resulted in an important decrease of plant physiological activity, vegetative growth, and productivity, and accelerated plant senescence at both water stress levels. Water deficit increased leaf reflectance in the visible and decreased it in the infrared ranges of the spectrum at both imposed stress levels. Foliar application of LCO affected overall plant physiological activity, increased flower and pod numbers. LCO treatment had the largest positive effect on the growth pattern of soybean at the medium stress level, which is the stress level most commonly observed in standard farm-field conditions. LCO treatment constitutes a potential technology for reducing water deficit effects. (Abstract shortened by UMI.)
118

Characterization and isomer differentiation of glycosides and oligosaccharides using chemical derivatization with quadrupole ion trap mass spectrometry

Pikulski, Michael, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
119

Chemical synthesis of oligosaccharide bacterial antigens /

Nilsson, Magnus, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.
120

Structural diversity of the lipid A and core oligosaccharide moieties of the lipopolysaccharides from nontypeable and serotype f Haemophilus influenzae /

Yildirim, Håkan, January 2005 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

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