Β-glucan Levels Research Articles

β-glucan in the lymph nodes in sarcoidosis and in Kveim-Siltzbach test reagent.

Background: Previous studies have demonstrated a relationship between biomass of fungi exposure in the home and the risk of sarcoidosis. β-glucan was present in the bronchial alveolar lavage fluid (BALF) of patients with sarcoidosis. The Kveim-Siltzbach test reagent (KSTR) induces a sarcoidosis specific, granulomatous, cutaneous response and was used to establish the diagnosis. To date, the granuloma-inducing component of KSTR is still unknown. The present study was undertaken to investigate the presence of β-glucan in the lymph nodes of patients with sarcoidosis and to determine the relationship between the amounts of this agent with disease severity and to investigate the presence of β-glucan in KSTR. Materials and methods: Lymph node aspirations were collected by transbronchial needle aspiration (TBNA) in region R4 or 7 from patients with newly diagnosed sarcoidosis. The samples were treated to isolate β-glucan and analyzed using a Limulus-based assay. Cultures of Propionibacterium ac. and Mycobacterium gordonae as well as samples of Kveim-Siltzbach test reagent were analyzed to determine β-glucan content. Results: A significant relationship was observed between the amount of the β-glucan in the lymph nodes and the extent of granuloma formation in the lung parenchyma, and the size of the lymph nodes in the mediastinum (r=0.787, p=0.0001 and r=0.664, p<0.001 respectively, Spearman's test). The samples of Kveim-Siltzbach test reagent contained high levels of β-glucan. Cultures of Propionibacterium ac. and Mycobacterium gordonae contained β-glucan, the levels of which were lower in the Mycobacterium cultures. Comments: The results support the hypothesis that β-glucan, and thus fungal exposure, are involved in the pathogenesis of sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 130-135).

Identification and characterization of high protein oat lines from a mutagenized oat population

Oat is an excellent source of high-quality proteins. The protein content in cultivated oat is about 12%–15%. Oats with even higher protein contents would have great potential as a vegetative protein source. From a mutagenized oat population, 230 lines with seed protein levels of 15% or higher were identified from green house grown plants. Fifteen lines with protein levels ranging between 17 and 24% were chosen for further studies. The high protein character was confirmed by two consecutive propagations in the field. Crossings showed that the trait was stable and segregated in a Mendelian fashion. SDS-PAGE analysis revealed that the major increase was in globulin like proteins. In addition, total dietary fibre, β-glucan and lipid levels were quantified. No correlation between any of these characters and the high protein trait could be found. Thousand Kernel Weight was also monitored and shown to be stable in the high protein lines. Thus, starting from the lines presented here a further development of commercial oat varieties with protein levels of 20% or higher is feasible. Such a high protein oat would be very important to meet the consumers need for high-quality high-protein oat for the food and feed industry.

Effect of dietary β-glucan on growth, survival and regulation of immune processes in rainbow trout (Oncorhynchus mykiss) infected by Aeromonas salmonicida

The present study evaluated the effects of dietary β-glucan (0, 0.05%, 0.1%, and 0.2%) on growth performance after 42 days of feeding. Thereafter, rainbow trout (Oncorhynchus mykiss) were infected with Aeromonas salmonicida, and survival rates as well as the regulating processes of stress- and immune-related factors were analyzed. In general, higher dietary β-glucan levels obviously improved specific growth rate (SGR), weight gain (WG) and feed efficiency (FE) (P ≤ 0.05). Survival rates in β-glucan groups increased significantly compared with the control group after A. salmonicida infection (P ≤ 0.05). Serum total superoxide dimutase (T-SOD), peroxidase (POD) as well as catalase (CAT) activities, and their mRNA expressions in the head kidney of fish in the β-glucan groups generally increased to higher levels after infection, and more quickly, compared with in the control group. Serum lysozyme (LSZ) and its expression in the head kidney in β-glucan groups reached a higher peak earlier than in the control group.Serum glutamic oxalacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) levels in the β-glucan groups were significantly lower than in the control group (P ≤ 0.05). The peak of heat shock protein 70 (HSP70) expression in the 0.2% β-glucan group was higher and occurred earlier than in other groups (P ≤ 0.05). These results confirm that 0.1% and 0.2% dietary β-glucan are beneficial for promoting growth in rainbow trout and enhancing resistance against A. salmonicida. Furthermore, β-glucan could play an important role in regulating stress- and immune-related factors in rainbow trout to more quickly fight against bacterial infection.

Oat β-glucan containing bread increases the glycaemic profile

A net postprandial glucose increment beyond 2h has been shown to improve glucose and appetite regulation at a subsequent meal. Such an improved glycaemic profile (GP) has been reported for bread containing guar gum. In the present study three commercially available β-glucans from barley and oat were baked into yeast leavened bread products. Only oat beta-glucan containing bread met the criteria of β-glucan molecular weight and was included in a meal study. The three levels of oat β-glucans reduced the GI and glucose iPeak by 32–37% compared to a white wheat reference bread. Furthermore, the highest oat β-glucan level increased GP by 66% compared to the reference bread. It is concluded that the oat β-glucans were suitable for use in baking, since the MW remained relatively high. Thus, the oat ingredient showed an interesting potential to be used when tailoring the glycaemic profile of bread products.

Candida pyralidae killer toxin disrupts the cell wall of Brettanomyces bruxellensis in red grape juice.

The control of the wine spoilage yeast Brettanomyces bruxellensis using biological methods such as killer toxins (instead of the traditional chemical methods, e.g. SO2 ) has been the focus of several studies within the last decade. Our previous research demonstrated that the killer toxins CpKT1 and CpKT2 isolated from the wine yeast Candida pyralidae were active and stable under winemaking conditions. In this study, we report the possible mode of action of CpKT1 on B.bruxellensis cells in red grape juice. Brettanomyces bruxellensis cells were exposed to CpKT1 either directly or through co-inoculation with C. pyralidae. This exposure yielded a temporary or permanent decline of the spoilage yeast population depending on the initial cell concentration. Scanning electron microscopy revealed cell surface abrasion while propidium iodide viability staining showed that CpKT1 caused plasma membrane damage on B.bruxellensis cells. Our data show that the exposure to CpKT1 resulted in increased levels of β-glucan, suggesting a compensatory response of the sensitive cells. The toxin CpKT1 causes cell membrane and cell wall damage in B. bruxellensis. Candida pyralidae shows potential to be used as a biocontrol agent against B. bruxellensis in grape juice/wine.

The Lipopolysaccharide Lipid A Long-Chain Fatty Acid Is Important for Rhizobium leguminosarum Growth and Stress Adaptation in Free-Living and Nodule Environments.

Rhizobium bacteria live in soil and plant environments, are capable of inducing symbiotic nodules on legumes, invade these nodules, and develop into bacteroids that fix atmospheric nitrogen into ammonia. Rhizobial lipopolysaccharide (LPS) is anchored in the bacterial outer membrane through a specialized lipid A containing a very long-chain fatty acid (VLCFA). VLCFA function for rhizobial growth in soil and plant environments is not well understood. Two genes, acpXL and lpxXL, encoding acyl carrier protein and acyltransferase, are among the six genes required for biosynthesis and transfer of VLCFA to lipid A. Rhizobium leguminosarum mutant strains acpXL, acpXL-/lpxXL-, and lpxXL- were examined for LPS structure, viability, and symbiosis. Mutations in acpXL and lpxXL abolished VLCFA attachment to lipid A. The acpXL mutant transferred a shorter acyl chain instead of VLCFA. Strains without lpxXL neither added VLCFA nor a shorter acyl chain. In all strains isolated from nodule bacteria, lipid A had longer acyl chains compared with laboratory-cultured bacteria, whereas mutant strains displayed altered membrane properties, modified cationic peptide sensitivity, and diminished levels of cyclic β-glucans. In pea nodules, mutant bacteroids were atypically formed and nitrogen fixation and senescence were affected. The role of VLCFA for rhizobial environmental fitness is discussed.

Minocycline Inhibits &lt;i&gt;Candida albicans&lt;/i&gt; Budded-to-Hyphal-Form Transition and Biofilm Formation

Candida albicans frequently causes bloodstream infections; its budded-to-hyphalform transition (BHT) and biofilm formation are major contributors to virulence. During an analysis of antibacterial compounds that inhibit C. albicans BHT, we found that the tetracycline derivative minocycline inhibited BHT and subsequent biofilm formation. Minocycline decreased expression of hypha-specific genes HWP1 and ECE1, and adhesion factor gene ALS3 of C. albicans. In addition, minocycline decreased cell surface hydrophobicity and the extracellular β-glucan level in biofilms. Minocycline has been widely used for catheter antibiotic lock therapy to prevent bacterial infection; this compound may also be prophylactically effective against Candida infection.

β-glucan Exposure on the Fungal Cell Wall Tightly Correlates with Competitive Fitness of Candida Species in the Mouse Gastrointestinal Tract

Candida albicans is responsible for ~400,000 systemic fungal infections annually, with an associated mortality rate of 46–75%. The human gastrointestinal (GI) tract represents the largest natural reservoir of Candida species and is a major source of systemic fungal infections. However, the factors that control GI colonization by Candida species are not completely understood. We hypothesized that the fungal cell wall would play an important role in determining the competitive fitness of Candida species in the mammalian GI tract. To test this hypothesis, we generated a systematic collection of isogenic C. albicans cell wall mutants and measured their fitness in the mouse GI tract via quantitative competition assays. Whereas a large variation in competitive fitness was found among mutants, no correlation was observed between GI fitness and total levels of individual cell wall components. Similar results were obtained in a set of distantly-related Candida species, suggesting that total amounts of individual cell wall components do not determine the ability of fungi to colonize the GI tract. We then subjected this collection of Candida strains and species to an extensive quantitative phenotypic profiling in search for features that might be responsible for their differences in GI fitness, but found no association with the ability to grow in GI-mimicking and stressful environments or with in vitro and in vivo virulence. The most significant association with GI fitness was found to be the strength of signaling through the Dectin-1 receptor. Using a quantitative assay to measure the amount of exposed β-glucan on the surface of fungal cells, we found this parameter, unlike total β-glucan levels, to be strongly predictive of competitive fitness in the mouse GI tract. These data suggest that fungal cell wall architecture, more so than its crude composition, critically determines the ability of fungi to colonize the mammalian GI tract. In particular, recognition of exposed β-glucan by Dectin-1 receptor appears to severely limit Candida GI fitness and hence represents a promising target to reduce fungal colonization in patients at risks of systemic candidiasis.

β-glucan in Lymph Nodes in Sarcoidosis Patients

SESSION TITLE: Sarcoidosis SESSION TYPE: Original Investigation Slide PRESENTED ON: Wednesday, October 26, 2016 at 07:30 AM - 08:30 AM PURPOSE: Previous studies have demonstrated a relation between fungal exposure at home and the risk of sarcoidosis. Β-glucan, a cell wall agent in fungi, was present in BALF of patients with sarcoidosis and at higher levels, there was a suppression of iNKT-cells and IL-10 and a relation to the severity of granuloma infiltration. The present study was undertaken prospectively to investigate the presence of β-glucan in lymph nodes of patients with sarcoidosis. The amount was also measured in Kveim’s agent. METHODS: TBNA lymph node aspiration by flexible fiberoptic bronchoscopy in regions R4 or R7 was performed in 40 patients with newly diagnosed sarcoidosis, stages II and I. The samples were treated to retrieve the non-soluble part of β-glucan and analysed using a Limulus based assay. Different CFUs/mL of Propionibacterium acnes and Mycobacterium gordonii in 1 ml of saline solution, as well as samples of Kveim’s agent were also analysed. RESULTS: The levels of ß-glucan in the lymph node samples ranged from 90 to 8350 pg/mL with a mean of 763 and SEM of 196. There was a significant relationship between the amount of non-soluble β-glucan in lymph nodes and the extent of granuloma formation in lung parenchyma (r = 0.8456 p<0.0001) and the size of lymph nodes in mediastinum (r=0.742; p<0.0001). The samples of Kveim’s agent contained high levels of non-soluble β-glucan, mean 3900 pg/mL, range 2500 to 5400 pg/mL. Different CFUs/mL of Propionibacterium acnes also contained different levels of β-glucan as did those of Mycobacterium gordonii although at lower levels. CONCLUSIONS: The results support a conclusion that non-soluble β-glucan and thus a higher level of fungal exposure is involved in the pathogenesis of sarcoidosis in susceptible patients. CLINICAL IMPLICATIONS: β-glucan should thus be recognized as a causative agent for sarcoidosis. It is likely that other microbial agents, not yet defined, have the same effect. DISCLOSURE: The following authors have nothing to disclose: Marjeta Tercelj-Zorman, Barbara Salobir, Ragnar Rylander No Product/Research Disclosure Information

A survey of total β-glucan content in Croatian barley varieties

Although β-glucans in cereals are desirable as healthy diet components, high levels of β-glucans in malting barley are unacceptable because they can cause unsatisfactory degradation of cell walls during malting. The aim of this study was to investigate the β-glucan content in twelve Croatian and two German barley varieties at three representative locations in Eastern Croatia over three consecutive seasons (2012–2014). Total β-glucan content in barley samples was determined using enzymatic method. Most of the investigated barley varieties had total β-glucan content lower or significantly lower than 4%. Furthermore, a distinct and clear genotype influence was noticed. No significant difference was found between years, but between locations Osijek and Tovarnik.

Influence of non-starchy polysaccharides on barley milling behavior and evaluating bioactive composition of milled fractions

Hulless barley cultivars grown at various altitudes were subjected to different conditioning treatments prior to roller milling. Amongst all treatments, conditioning grains to a moisture content of 14% for 30min was found to be optimum. The bran fractions displayed greater levels of non-starchy polysaccharides and bioactive components as compared to refined flour fraction. The presence of greater levels of β-glucan in whole barley flour and bran of high altitude cultivars affected the refined flour yield inversely. Cultivars having higher total and insoluble arabinoxylans also resulted in lower flour yields (R=−0.76; R=−0.73). The damaged starch content of barley cultivars ranged between 5.1% and 8.7% which correlated positively with the content of β-glucans (up to R=0.77) and arabinoxylans (up to R=0.80) in bran and refined flour fractions. The anthocyanin and total phenolic contents of refined flours ranged between 3.9–7.6μg/g and 1299–1607μg FAE/g and was higher for high altitude cultivars.

High wholegrain barley β-glucan lowers food intake but does not alter small intestinal macronutrient digestibility in ileorectostomised rats

Using barley cultivars differing widely in β-glucan content, we aimed to determine their effects on small intestinal macronutrient digestion in 24 ileorectostomised rats. The rats were fed 1 of 4 experimental diets, each containing a different barley variety, for 11 d. The diets had a content of 0, 2.1, 2.6 and 4.3 g of β-glucan/100 g. Feed intake and faecal excretion of fat, protein, starch, and non-starch polysaccharides were determined in the final 5 d of the study and apparent macronutrient digestibility calculated. Higher dietary levels of β-glucan (2.6% and 4.3%) lowered feed intake (by 15 and 19%, respectively) but final body weight was only lowered by the 4.3% β-glucan diet relative to rats fed the 0% β-glucan diet (all ps < 0.05). Protein, lipid and starch digestibility was unrelated to the dietary β-glucan content. Higher dietary levels of barley β-glucan lower feed intake of ileorectostomised rats, which is independent of intestinal fermentation and unrelated to macronutrient digestibility.

Loss of efficacy of the antifungal caspofungin is mediated by increased chitin exposure and concomitant eosinophilia in invasive pulmonary aspergillosis

Abstract Recently significant interest has focused on the composite recognition of fungal molecular patterns that program innate and adaptive immunity to the human fungal pathogen Aspergillus fumigatus. We observed that decreased relative levels of cell wall β-glucan to chitin in A. fumigatus strains correlated with increased airway eosinophil recruitment associated with decreased fungal clearance by type 2 immune responses in invasive pulmonary aspergillosis. Furthermore, an increase in surface chitin exposure driven by growth and germination in the presence of the anti-fungal, β-glucan targeting drug caspofungin resulted in increased airway eosinophilia upon aspiration of A. fumigatus conidia. More importantly, in a model of invasive aspergillosis, we observed a decrease in fungal clearance upon caspofungin treatment that was reversed in eosinophil-deficient mice. Eosinophil recruitment was partially dependent on γδ T cells, and our preliminary results show a similar increase in caspofungin mediated clearance in γδ-T cell-deficient mice. Our results provide a novel mechanism that may explain the widely reported paradoxical loss of efficacy in response to caspofungin, and we are currently working to define the relationship between drug treatment, eosinophil activation, and fungal burden in clinical samples.

Genetic Diversity and Genome Wide Association Study of β-Glucan Content in Tetraploid Wheat Grains

Non-starch polysaccharides (NSPs) have many health benefits, including immunomodulatory activity, lowering serum cholesterol, a faecal bulking effect, enhanced absorption of certain minerals, prebiotic effects and the amelioration of type II diabetes. The principal components of the NSP in cereal grains are (1,3;1,4)-β-glucans and arabinoxylans. Although (1,3;1,4)-β-glucan (hereafter called β-glucan) is not the most representative component of wheat cell walls, it is one of the most important types of soluble fibre in terms of its proven beneficial effects on human health. In the present work we explored the genetic variability of β-glucan content in grains from a tetraploid wheat collection that had been genotyped with a 90k-iSelect array, and combined this data to carry out an association analysis. The β-glucan content, expressed as a percentage w/w of grain dry weight, ranged from 0.18% to 0.89% across the collection. Our analysis identified seven genomic regions associated with β-glucan, located on chromosomes 1A, 2A (two), 2B, 5B and 7A (two), confirming the quantitative nature of this trait. Analysis of marker trait associations (MTAs) in syntenic regions of several grass species revealed putative candidate genes that might influence β-glucan levels in the endosperm, possibly via their participation in carbon partitioning. These include the glycosyl hydrolases endo-β-(1,4)-glucanase (cellulase), β-amylase, (1,4)-β-xylan endohydrolase, xylanase inhibitor protein I, isoamylase and the glycosyl transferase starch synthase II.

Dietary β-glucan improved growth performance, Vibrio counts, haematological parameters and stress resistance of pompano fish, Trachinotus ovatus Linnaeus, 1758.

This study evaluated effects of graded levels of dietary β-glucan (0, 0.5, 1, 2 and 4gkg(-1)) on growth performance, haematological parameters, intestinal Vibrio counts, dose requirement and salinity stress resistance in pompano fish Trachinotus ovatus (6.45g±0.06 (SEM)). After 8-weeks of diet feeding, growth was significantly higher in fish fed diets with 0.10% β-glucan compared to fish fed control diet (no β-glucan). Survival increased significantly in fish fed 0.05 and 0.10% β-glucan compared to control diet. There were significant increases in red blood cells (in 0.20% β-glucan diet), in total leukocytes (in 0.05-0.20% β-glucan diet), in both lymphocyte and monocyte count in fish fed 0.10%-0.40% β-glucan diet. However, dietary β-glucan did not affect neutrophil, eosinophil and basophil counts. Intestinal Vibrio counts were reduced in fish fed any level of β-glucan compared to control. In addition, dietary β-glucan levels highly correlated with growth, survival, intestinal Vibrio counts and haematological index. Optimal β-glucan levels for maximal growth of fish were predicted to be 0.122% at day 21 (R(2)=98.53%), 0.120% at day 28 (R(2)=78.55%), 0.115% at day 42 (R(2)=62.21%) and 0.090% at day 56 (R(2)=75.18%), showing a decreasing β-glucan requirement with increasing fish size. Furthermore, optimal β-glucan levels for maximal haematological parameters based on lymphocyte count, was estimated to be 0.120% (R(2)=98.53%) at day 56. Also, fish fed 0.05%-0.20% β-glucan showed better resistance against salinity stress. In conclusion, β-glucan supplementation is effective for improving growth, intestinal Vibrio counts and boosted stress resistance of the pompano fish, T.ovatus.

Members of the Candida parapsilosis Complex and Candida albicans are Differentially Recognized by Human Peripheral Blood Mononuclear Cells

The systemic infections caused by members of the Candida parapsilosis complex are currently associated to high morbility and mortality rates, and are considered as relevant as those caused by Candida albicans. Since the fungal cell wall is the first point of contact with the host cells, here we performed a comparison of this organelle in members of the C. parapsilosis complex, and its relevance during interaction with human peripheral blood mononuclear cells (PBMCs). We found that the wall of the C. parapsilosis complex members is similar in composition, but differs to that from C. albicans, with less mannan content and more β-glucan and porosity levels. Furthermore, lectin-based analysis showed increased chitin and β1,3-glucan exposure at the surface of C. parapsilosis sensu lato when compared to C. albicans. Yeast cells of members of the C. parapsilosis complex stimulated more cytokine production by human PBMCs than C. albicans cells; and this significantly changed upon removal of O-linked mannans, indicating this wall component plays a significant role in cytokine stimulation by C. parapsilosis sensu lato. When inner wall components were exposed on the wall surface, C. parapsilosis sensu stricto and C. metapsilosis, but not C. orthopsilosis, stimulated higher cytokine production. Moreover, we found a strong dependency on β1,3-glucan recognition for the members of the C. parapsilosis complex, but not for live C. albicans cells; whereas TLR4 was required for TNFα production by the three members of the complex, and stimulation of IL-6 by C. orthopsilosis. Mannose receptor had a significant role during TNFα and IL-1β stimulation by members of the complex. Finally, we demonstrated that purified N- and O-mannans from either C. parapsilosis sensu lato or C. albicans are capable to block the recognition of these pathogens by human PBMCs. Together; our results suggest that the innate immune recognition of the members of the C. parapsilosis complex is differential of that reported for C. albicans. In addition, we propose that purified cell wall mannans can be used as antagonist to block specific receptors on innate immune cells.

Inhibitory Role of Greatwall-Like Protein Kinase Rim15p in Alcoholic Fermentation via Upregulating the UDP-Glucose Synthesis Pathway in Saccharomyces cerevisiae.

The high fermentation rate of Saccharomyces cerevisiae sake yeast strains is attributable to a loss-of-function mutation in the RIM15 gene, which encodes a Greatwall-family protein kinase that is conserved among eukaryotes. In the present study, we performed intracellular metabolic profiling analysis and revealed that deletion of the RIM15 gene in a laboratory strain impaired glucose-anabolic pathways through the synthesis of UDP-glucose (UDPG). Although Rim15p is required for the synthesis of trehalose and glycogen from UDPG upon entry of cells into the quiescent state, we found that Rim15p is also essential for the accumulation of cell wall β-glucans, which are also anabolic products of UDPG. Furthermore, the impairment of UDPG or 1,3-β-glucan synthesis contributed to an increase in the fermentation rate. Transcriptional induction of PGM2 (phosphoglucomutase) and UGP1 (UDPG pyrophosphorylase) was impaired in Rim15p-deficient cells in the early stage of fermentation. These findings demonstrate that the decreased anabolism of glucose into UDPG and 1,3-β-glucan triggered by a defect in the Rim15p-mediated upregulation of PGM2 and UGP1 redirects the glucose flux into glycolysis. Consistent with this, sake yeast strains with defective Rim15p exhibited impaired expression of PGM2 and UGP1 and decreased levels of β-glucans, trehalose, and glycogen during sake fermentation. We also identified a sake yeast-specific mutation in the glycogen synthesis-associated glycogenin gene GLG2, supporting the conclusion that the glucose-anabolic pathway is impaired in sake yeast. These findings demonstrate that downregulation of the UDPG synthesis pathway is a key mechanism accelerating alcoholic fermentation in industrially utilized S. cerevisiae sake strains.

Effects of dietary β-glucan on the growth and innate immune response of juvenile Persian sturgeon, Acipenser persicus.

The present study evaluated the effects of different levels of dietary β-glucan (MacroGard(®)) on growth performance and innate immune parameters in juvenile Persian sturgeon (Acipenser persicus). Fish (20.1 ± 0.8 g) were allocated into 12 tanks (15 fish per tank) and triplicate groups were fed a control diet or diets containing 0.1%, 0.2% and 0.3% β-glucan. After six weeks of daily feeding (3.0% body weight day(-1)), humoral innate immune parameters (serum immunoglobulin (Ig) levels, lysozyme activity and alternative complement activity (ACH50)) and growth parameters (final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR)) were examined. Innate immune responses (lysozyme activity and ACH50) were significantly higher in 0.2% and 0.3% β-glucan fed fish (P < 0.05). Similarly, elevated growth performance (final weight, SGR and FCR) was observed in fish fed 1%, 2% and 3% β-glucan compared to the control group (P < 0.05). However, dietary β-glucan had no significant effect on survival rate of fish (P > 0.05). These results indicate that β-glucan can be considered as a beneficial dietary supplement for improving the immune response and growth performance of Persian sturgeon.

Starch digestibility and bioactivity of high altitude hulless barley

This study was aimed at evaluating the effects of growth altitude (97–3500m) on the starch digestibility and bioactivity of hulless barley cultivars grown in India. All the high altitude cultivars (between 1200 and 3500m above sea level) displayed 7.5–30.8% higher levels of total β-glucan, 39.8–68.6% higher arabinoxylan content, 11.0–60.9% higher total anthocyanin content and 16.6–43.2% higher metal chelating activity than the cultivars grown in plains (97–126m altitude). The soluble β-glucan and arabinoxylan content of cultivars ranged from 2.0% to 2.8% and 0.08% to 0.19%. A positive correlation between slowly digestible starch (SDS) and insoluble β-glucan and total arabinoxylan content was observed. Cultivars grown at higher altitudes exhibited higher bioactive potential and may find better utilization in nutraceutical foods.

The effects of feeding immunostimulant β-glucan on the immune response of Pangasianodon hypophthalmus

Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.