Glucans are (1→3)-β-D-glucose polymers that are found in the cell wall of fungi, bacteria and plants. Glucans are known to stimulate humoral and cell-mediated immunity in humans and animals. In addition to the potent immune stimulatory effects of (1→3)-β-D-glucans, there are a number of toxicological effects associated with exposure to the water-insoluble, microparticulate form of the polymer. Recent investigations have suggested a potential role for (1→3)-β-D-glucans in inhalational toxicity. Specifically, (1→3)-β-D-glucans have been implicated in the symptomatology associated with 'sick building' syndrome. The mechanisms by which (1→3)-β- D-glucans mediate immune stimulation and, perhaps, toxicity are currently under investigation. It is now established that (1→3)-β-D-glucans are recognized by macrophages and, perhaps, neutrophils and natural killer cells via a (1→3)-β-D-glucan specific receptor. Following receptor binding, glucan modulates macrophage cytokine expression. Here we review the chemistry, immunobiology and toxicity of (1→3)-β-D-glucans and how it may relate to effects caused by inhalation.

Bibliography: leaves 132-155. / viii, 155 leaves : ill., plates, charts (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A putative callose synthase gene, designated HvGSL1 cDNA is siolated from barley and its involvement in callose biosynthesis is investigated. A near-full length HvGSL1 cDNA encoded a protein showing approximately 30% identitly with that of yeast FKS genes at the amino acid level. The function of this geen was investigated by heterologous expression, protein purification, immunochemistry and mass spectrometric analysis. Results provide strong evidence that the gene encodes a protein which is associated with callose synthase activity, and is likely to encode the catalytic subunit of the synthase complex. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2003

Bibliography: leaves 132-155. / viii, 155 leaves : ill., plates, charts (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A putative callose synthase gene, designated HvGSL1 cDNA is siolated from barley and its involvement in callose biosynthesis is investigated. A near-full length HvGSL1 cDNA encoded a protein showing approximately 30% identitly with that of yeast FKS genes at the amino acid level. The function of this geen was investigated by heterologous expression, protein purification, immunochemistry and mass spectrometric analysis. Results provide strong evidence that the gene encodes a protein which is associated with callose synthase activity, and is likely to encode the catalytic subunit of the synthase complex. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2003

This research was conducted to determine the potential of hulless winter barley (Hordeum vulgare L.) as an improved feed crop in the mid-Atlantic region. Winter barley is an excellent crop in rotation with soybean (Glycine max L.); however, production of winter barley during the past few years has decreased mainly due to low market prices, even though the mid-Atlantic region is a feed grain deficient area. Therefore, value added traits need to be developed in order for barley production to continue in the region. In the first part of this study, the objectives were to: (i) evaluate the agronomic performance and potential of six experimental hulless winter barley lines compared with two commercial hulled cultivars; (ii) determine and compare fiber, b-glucan, protein, and fat concentrations, and true metabolizable energy, corrected for nitrogen (TMEn) among these genotypes; and (iii) evaluate the genetic potential of winter hulless barley accessions from the world collection for use as parents in hulless breeding programs. Six hulless lines all derived from the cross VA75-42-45/SC793556//CI2457 were acquired from Clemson University in South Carolina. The six lines were evaluated for yield, test weight, heading date, plant height, and lodging. These hulless lines along with two hulled cultivars were planted in replicated yield plots in four states with a total of eight locations, and were managed according to standard recommended practices. Grain from each of the hulless lines and hulled checks, along with that of Trical 498 triticale (X Triticosecale) and Jackson wheat (Triticum aestivum L.) were analyzed for fiber, b-glucan, fat, protein, and ash concentration, and TMEn value. Eight hundred and seven winter or facultative habit hulless barley lines were obtained from the USDA-ARS National Small Grains Collection in Aberdeen, ID. These lines were screened for reaction type to races 8 and 30 of barley leaf rust (Puccinia hordei) and to a composite population of powdery mildew (Blumeria graminis f. sp. hordei). These accessions also were planted in observation rows to evaluate heading date, plant height, lodging, and seed threshability. The hulless lines yielded 23% less, but had 13% higher test weights than the hulled check cultivars. There was no difference between hulled and hulless barley in heading date and plant height. Hulless lines had a higher protein and lower fiber concentration than hulled barley. They also had higher b-glucan and fat concentrations than triticale or wheat. TMEn was similar between hulled and hulless barley, triticale, and wheat. Approximately 100 hulless barley lines from the world collection were selected for potential use as parents among 800 accessions tested, based on evaluations of lodging, plant height, threshability, and seed color. In the second part of the study the objectives were to determine the effects of (i) hulled and hulless barley, and (ii) b-glucanase on the performance of broilers fed different diets from 21 to 42 days of age. Diets comprised of 30% hulless or hulled barley, and a standard corn (Zea mays)/soybean meal diet with and without b-glucanase enzyme were evaluated to determine the effects of barley on gut viscosity, carcass weight, gain, percent shell, and feed efficiency in 21 to 42 day old broilers. In the first year, diets comprised of hulless lines SC890573 and SC860972, and the hulled cultivar Callao were compared to a standard check diet. In the second year SC860972 was replaced with SC880248 due to the inability to secure a sufficient amount of seed. Each year one hulled and two hulless barley diets were compared to a standard diet. Each diet was fed with and without enzyme, for a total of eight diets. Broilers 21 days of age were fed the diets until day 42 when they were processed. There was a significant decrease (P<0.05) in gut viscosity of birds fed diets with enzyme compared to birds fed diets without enzyme; however, gut viscosity did not affect weight gain or percent shell. Barley substituted at the 30% level did not have a significant effect on broiler performance, nor did the addition of enzyme. Absence of enzyme effect was attributed to bird age, since older birds are able to hydrolyze b-glucan more effectively than juveniles. The potential of hulless barley as an improved feed source for the poultry and swine industry is great for the mid-Atlantic region. Increases in grain yield are currently being realized through focused breeding efforts, and hulless lines exhibit positive nutritional components that combine favorable attributes of both wheat and hulled barley. Barley substituted at the 30% level in the diets of broilers did not cause any detrimental effects. Addition of hulless barley may potentially lead to a reduction in cost per pound of gain of broilers, and provide an alternative crop for mid-Atlantic region grain producers and feeders. / Ph. D.

Justification - Endotoxemia is an important contributor to mortality and loss of use in the horse and results in significant losses to the equine industry on an annual basis. Objective - To determine the effect of PGG-Glucan on the cytokine response to endotoxin in the horse. Animals - Part 1; 6 adult horses. Part 2; 12 adult horses. Procedure - Part 1; Whole blood was collected, aliquoted, and incubated in vitro in four groups; saline control, endotoxin (LPS) (100 ng/ml), PGG-Glucan (0.1, 1.0, 10 and 100 μg/ml) and LPS (100 ng/ml) plus PGG-Glucan (0.1, 1.0, 10 and 100 μgg/ml). Supernatants were collected at 0, 6 and 12 hours and assayed for tumor necrosis factor £\ (TNF£\) activity. Part 2; Horses received either PGG-Glucan (1 mg/kg) or an equal volume of isotonic saline (0.9% NaCl) IV over 15 minutes. Twenty four hours later blood was collected and mononuclear cells isolated for cell culture. Cells were treated with LPS (100 ng/ml) and RNA extractions were performed at 0, 6, 12, 24 and 48 hours. Relative mRNA expression of TNFα, interleukin-1β (IL-1β),, interleukin-10 (IL-10) and interferon-γ (IFN-γ) was determined by reverse transcription and real time polymerase chain reaction. Results - Using an in vitro endotoxin challenge method PGG-Glucan altered the production of TNFα in a dose-dependent manner. PGG-Glucan had no effect upon the ex vivo cytokine mRNA expression of TNFα, IL-1β, IL-10 or IFN-γ. Conclusions and Relevance - Although mild changes were observed in TNFα production in vitro, it is not likely that PGG-Glucan will have a significant effect upon clinical endotoxemia. / Master of Science

Starch is the main storage biopolymer in cereal plants. Several enzymes and carrier proteins are involved in the starch biosynthesis process. ADP-glucose pyrophosphorylase (AGPase) has been characterized as a key factor in this process, which catalyzes the conversion of glucose 1-phosphate into ADP-glucose in the cytosol of the endospermic cell. The freshly synthesized ADP-glucose must be transported into amyloplasts by the activity of ADP-glucose transporter. In the current research, we have characterized HvBT1 biochemically in E. coli system. HvBT1 shows high affinity to ADP-glucose as a transport substrate in counter-exchange with ADP with affinities of 614 and 334 µM, respectively. The cellular and subcellular localization of HvBT1 indicated its target the amyloplasts envelopes. The comparison between two barley cultivars; Harrington and Golden Promise shed some light on the impact of HvBT1 on starch accumulation. Higher expression of AGPase and HvBT1 (10 fold) provide an ideal combination for improving starch yield, where starch content was higher by 2.5% in Harrington. Unlike Harrington, the expression of soluble starch synthase encoded genes was higher in Golden Promise which accumulates less starch. This result provided evidence of the importance of HvBT1 in starch synthesis process along with AGPase. Down-regulation of HvBT1 also provided a cement evidence of its effect on the starch accumulation process, where the knock down lines showed 17% lower starch and altered starch composition. Also, as a result of decreasing starch, protein content increased in the transgenic grains by 4-5 % of its content in the wild type, while β-glucan was 37% lower than the wild type control. Down-regulation of HvBT1 led to decrease the grain yield by ~ 30% as a result of increase the grain size. Also, it seems to have pleotropic effects on other starch synthesis genes, where AGPLs was down-regulated while the plastidial SSU genes, AGPS1b and S2 were up-regulated. Soluble starch synthases SS2a and SS3a were down-regulated, while SS2b was up-regulated in the transgenic plants. The accumulated evidences indicated that HvBT1 is a key factor in starch biosynthesis process. / February 2015

Acidified dairy products are one of the oldest types of food products. Unfortunately all of them are low in dietary fibre. Thus, to improve health benefit of these products the idea of fortifying them with dietary fibre seems attractive. However dairy products enriched with Glucagel (a commercial product that is high in barley β-glucan) were found to suffer from textural defects. When the Glucagel concentration exceeded a certain value (5 g/L), dramatic phase separation was observed in set yogurt and yogurt drink with volume fraction of casein micelles greater then 0.108. To investigate interactions of β-glucan polymers and casein micelles in the milk prior to setting of yogurt, mixtures of yogurt milk and Glucagel were systematically studied. Depending on the volume fraction of casein micelles and the Glucagel concentration, a stable phase or a gel or a sedimented material could exist. The driving force for phase separation was depletion flocculation of casein micelles in the presence of β-glucan. The phase separation responsible for textural defects in yogurt systems supplemented with high amounts of Glucagel can be avoided by the reduction of β-glucan molecular weight, a process that limits the range of attraction between micelles. Incubation of Glucagel with lichenase for 90 min resulted in homogeneous (stable) yogurt systems with Glucagel concentrations as high as 10 g/L.

Acidified dairy products are one of the oldest types of food products. Unfortunately all of them are low in dietary fibre. Thus, to improve health benefit of these products the idea of fortifying them with dietary fibre seems attractive. However dairy products enriched with Glucagel (a commercial product that is high in barley β-glucan) were found to suffer from textural defects. When the Glucagel concentration exceeded a certain value (5 g/L), dramatic phase separation was observed in set yogurt and yogurt drink with volume fraction of casein micelles greater then 0.108. To investigate interactions of β-glucan polymers and casein micelles in the milk prior to setting of yogurt, mixtures of yogurt milk and Glucagel were systematically studied. Depending on the volume fraction of casein micelles and the Glucagel concentration, a stable phase or a gel or a sedimented material could exist. The driving force for phase separation was depletion flocculation of casein micelles in the presence of β-glucan. The phase separation responsible for textural defects in yogurt systems supplemented with high amounts of Glucagel can be avoided by the reduction of β-glucan molecular weight, a process that limits the range of attraction between micelles. Incubation of Glucagel with lichenase for 90 min resulted in homogeneous (stable) yogurt systems with Glucagel concentrations as high as 10 g/L.

Glucans are (1-3)-β-D-linked polymers of glucose that are produced as fungal cell wall constituents and are also released into the extracellular milieu. Glucans modulate immune function via macrophage participation. The first step in macrophage activation by (1-3)-β-D-glucans is thought to be the binding of the polymer to specific macrophage receptors. We examined the binding/uptake of a variety of water soluble (1-3)-β-D-glucans and control polymers with different physicochemical properties to investigate the relationship between polymer structure and receptor binding in the CR3- human promonocytic cell line, U937. We observed that the U937 receptors were specific for (1→3)-β-D-glucan binding, since mannan, dextran, or barley glucan did not bind. Scleroglucan exhibited the highest binding affinity with an IC50 of 23 nM, three orders of magnitude greater than the other (1→3)-β-D-glucan polymers examined. The rank order competitive binding affinities for the glucan polymers were scleroglucan >>> schizophyllan > laminarin > glucan phosphate > glucan sulfate. Scleroglucan also exhibited a triple helical solution structure (ν = 1.82, β = 0.8). There were two different binding/uptake sites on U937 cells. Glucan phosphate and schizophyllan interacted nonselectively with the two sites. Scleroglucan and glucan sulfate interacted preferentially with one site, while laminarin interacted preferentially with the other site. These data indicate that U937 cells have at least two non-CR3 receptor(s) which specifically interact with (1→3)-β-D-glucans and that the triple helical solution conformation, molecular weight and charge of the glucan polymer may be important determinants in receptor ligand interaction.

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