epiglucan and Disease-Resistance

Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are caused by various factors, including both pathogenic and non-pathogenic ones. β-glucan primarily originates from bacteria and fungi, some species of these organisms work as biological agents in causing diseases. When β-glucan enters plants, it triggers the defense system, leading to various reactions such as the production of proteins related to pathogenicity and defense enzymes. By extracting β-glucan from disturbed microorganisms and using it as an inducing agent, plant diseases can be effectively controlled by activating the plant's defense system. β-glucan plays a crucial role during the interaction between plants and pathogens. Therefore, modeling the plant-pathogen relationship and using the molecules involved in this interaction can help in controlling plant diseases, as pathogens have genes related to resistance against pathogenicity. Thus, it is reasonable to identify and use biological induction agents at a large scale by extracting these compounds.

Topics: beta-Glucans; Disease Resistance; Plant Diseases; Plant Proteins; Plants

The general understanding has been that only adaptive immunity is capable of immunological memory, but this concept has been challenged in recent years by studies showing that innate immune systems can mount resistance to reinfection-as the innate immune system can adapt its function following an insult. Innate immune training offers an attractive approach in intensive fish larval rearing, especially since the adaptive immune system is not fully developed. Trained innate immunity will potentially favor robust fish in terms of resistance to viral and bacterial diseases. So-called immunostimulants such as ß-glucans have for decades been used both in laboratories and in intensive fish aquaculture. Treatment of fish by ß-glucans (and by other substances with pathogen-associated molecular patterns) often induces activation of non-specific/innate immune mechanisms and induces higher disease resistance. The reported effects of e.g., ß-glucans fit nicely into the concept "trained innate immunity," but the research on fish does not yet include analysis of epigenetic changes that may be a prerequisite for long-lasting trained innate immunity. In this "perspective," we will discuss how in practical terms and based on prior knowledge one can introduce innate immune training in brood stock fish, and their offspring, and whether innate immune training by ß-glucans is a viable approach in larval aquaculture.

Topics: Adjuvants, Immunologic; Animals; Aquaculture; beta-Glucans; Disease Resistance; Fish Diseases; Fishes; Immune System; Immunity, Innate; Immunologic Memory; Larva

A 56-day feeding trial was conducted to determine the effect of dietary supplementation with

Topics: Animal Feed; Animals; Bacillus; beta-Glucans; Dietary Supplements; Disease Resistance; Gastrointestinal Microbiome; Perciformes; Sea Bream

An eight-week feeding trial was performed to assess the effect of different dietary levels (0, 0.5, 1.0, and 1.5%) of β-glucan (sourced from Saccharomyces cerevisiae) on growth, survival, immunological parameters (immune gene expression, lysozyme, and antiprotease), total antioxidant status, thermal tolerance, and disease resistance of Tor putitora fry. Feeding of moderate doses (0.5 and 1.0%) of β-glucan significantly improved survival but not weight gain percentage as compared to that received unsupplemented control and highest dose (1.5%) of glucan. Supplementation of β-glucan in diets differentially influenced the mRNA expression of cytokine and other immune genes. For instance, transcripts of cytokines such as tnf-α and il-1β were significantly upregulated, while ifn-γ and il-10 were unaffected by β-glucan intake. Also, the relative mRNA expression of tlr-5 and hepcidin1 along with lysozyme and antiprotease activities were remained largely unchanged by dietary glucan administration. In contrast, β-glucan induced mRNA expression of defensin1 and c3 while decreased the transcript level of mhc-1. On the other hand, dietary inclusion of β-glucan markedly improved total antioxidant levels and extended the thermal tolerance limits at both the ends, as shown by increased CT

Topics: Aeromonas salmonicida; Animal Feed; Animals; Antioxidants; beta-Glucans; Cyprinidae; Disease Resistance; Fish Diseases; Gene Expression; Gram-Negative Bacterial Infections; Muramidase; Protease Inhibitors; RNA, Messenger

Pattern-triggered immunity (PTI) is activated in plants upon recognition by pattern recognition receptors (PRRs) of damage- and microbe-associated molecular patterns (DAMPs and MAMPs) derived from plants or microorganisms, respectively. To understand better the plant mechanisms involved in the perception of carbohydrate-based structures recognized as DAMPs/MAMPs, we have studied the ability of mixed-linked β-1,3/1,4-glucans (MLGs), present in some plant and microbial cell walls, to trigger immune responses and disease resistance in plants. A range of MLG structures were tested for their capacity to induce PTI hallmarks, such as cytoplasmic Ca

Topics: Arabidopsis; beta-Glucans; Calcium; Capsicum; Cell Wall; Disease Resistance; Oomycetes; Plant Diseases; Plant Immunity; Solanum lycopersicum; Trisaccharides

The effects of dietary β-glucan on innate immune responses have been shown in a number of different vertebrate species. However, there is conflicting information about the period of administration (shorter vs. longer), and it is also unclear to what extent β-glucan's effects can be observed post-treatment in fish. Thus, we fed Nile tilapia for 0 (control group; 45 days of control diet), 15 (30 days of control followed by 15 days of β-glucan), 30 (15 days of control followed by 30 days of β-glucan) or 45 days with a diet containing 0.1% of β-glucan (MacroGard®). We evaluated the growth performance at the end of the β-glucan feeding trial and the innate immune function immediately after the feeding trial and 7 and 14 days post-feeding trial. In addition, at day 10 post-feeding trial, we assessed the tilapia's resistance against a bacterial infection. No significant differences were observed in growth performance between the groups; however, fish fed with β-glucan for 30 and 45 days had higher (approx. 8%) relative weight gain compared to the control. Regardless of the administration period, fish fed with β-glucan had higher innate immune responses immediately after the feeding trial such as lysozyme activity in plasma, liver and intestine and respiratory burst compared to the control, and in general these differences were gradually reduced over the withdrawal period (up to 14 days). No differences were observed in the plasma hemolytic activity of the complement or myeloperoxidase activity in plasma or intestine. Moreover, fish from the control group had early mortalities (2 vs. 4-5 days post-infection, respectively) and a lower survival rate (60 vs. 80%, respectively) compared to fish fed with β-glucan for 15 or 30 days, and, interestingly, fish fed for 45 days with β-glucan had no mortality. This study indicates that regardless of the administration period (i.e., 15 up to 45 days), the β-glucan improved the innate immune responses and the tilapia's resistance to disease, and this protection could be observed up to 10 days post-feeding trial, adding in vivo evidence that β-glucan may contribute to a trained innate immunity. Additionally, we showed that a longer period of administration did not cause immunosuppression as previously hypothesized but promoted further growth and immune performance. These findings are relevant to the aquaculture industry and demonstrate that a longer β-glucan feeding protocol may be considered to achieve better results.

Topics: Aeromonas; Animal Feed; Animals; beta-Glucans; Cichlids; Diet; Dietary Supplements; Disease Resistance; Fish Diseases; Gram-Negative Bacterial Infections; Immunity, Innate; Random Allocation; Streptococcal Infections; Streptococcus agalactiae

A trial was operated to assess the potential of using Lactobacillus plantarum L-137 (L-137) and/or β-glucan (BG) in improving the resistance of Nile tilapia against Aeromonas hydrophila. Control diet and 3 diets supplemented with L-137, BG or L-137 + BG were prepared. Final body weight, specific growth rate, superoxide dismutase, and catalase showed considerably (P < .05) increased values in L-137 or L-137/BG groups, while glutathione peroxidase increased significantly (P < .05) only in L-137/BG group. Fish fed L-137 and/or BG diets showed that feed conversion ratio and malonaldehyde levels were significantly decreased (P < .05). Also, both L-137 and BG helped Nile tilapia to have high phagocytosis activity and relative expression of tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL-1β) and interferon-gamma (INF-γ) genes. After A. hydrophila challenge, the intestinal villi epithelium of the L-137/BG group was intact and denser than the other groups. The hepatopancreas and spleen of the control group displayed severe necrosis in hepatocytes and congestion of blood sinusoids in addition to diffuse vacuolation. Regarding the L-137, BG and L-137/BG groups, there was a moderate and normal degree of vacuolation with focal necrosis and mild to moderate degree of congestion of blood sinusoids. Red blood cells, hemoglobin, and albumin showed meaningfully (P < .05) increased values in L-137 or L-137/BG groups. TNF-α, IL-1β, and INF-γ expressions were upregulated by L-137 and/or BG. The obtained results revealed the ability of L-137 and/or BG to protect Nile tilapia from the effects of A. hydrophila infection by the motivation of the immune, antioxidative, and antiinflammation responses.

Topics: Adjuvants, Immunologic; Aeromonas hydrophila; Animal Feed; Animals; Antioxidants; beta-Glucans; Diet; Disease Resistance; Fish Diseases; Fish Proteins; Gram-Negative Bacterial Infections; Lactobacillus plantarum; Probiotics

The purpose of this study was to evaluate Bacillus sp. SJ-10, isolated from traditional Korean seafood, as a probiotic. Strain SJ-10 was demonstrated to be safe, on the basis of in vitro tests confirming the absence of cytotoxicity, hemolysis, and genes with toxigenic potential, and was susceptible to antibiotics. It met the probiotic prerequisites of a spore count that remained almost constant, acid and bile tolerance under simulated gastrointestinal conditions, and significant adhesion to Caco-2 cells. Moreover, SJ-10 demonstrated beneficial properties as a probiotic: broad-spectrum antimicrobial activity, hydroxyl radical, antioxidant activity, production of functional enzymes such as β-galactosidase and phytase, and selective growth via β-glucan fermentation. The fish-feeding trial demonstrated that olive flounder fed diets containing SJ-10 alone or in combination with β-glucan exhibited significantly higher growth performance and pathogenic disease resistance compared with those fed diets containing β-glucan alone, indicating that SJ-10 diets exerted a beneficial effect as an antibiotic replacer in terms of growth performance and disease resistance in olive flounder.

Topics: 6-Phytase; Animals; Antioxidants; Aquaculture; Bacillus; beta-Galactosidase; beta-Glucans; Biological Control Agents; Caco-2 Cells; Cell Line, Tumor; Disease Resistance; Fermented Foods; Fish Diseases; Flounder; Hordeum; Humans; Probiotics; Seafood; Synbiotics

β-glucan is one of the most potent immunostimulants enhancing innate immune activity, disease resistance and growth performance of many aquatic organisms. Nevertheless, there are few studies on feeding regimens of β-glucan that correlate to immune response and disease resistance and are important considerations for practical β-glucan utilization. Thus, the effect of β-glucan and feeding duration on innate immunity and disease resistance was investigated to establish an optimal feeding regimen of β-glucan for Nile tilapia (Oreochromis niloticus Linn.). A variety of β-glucan feeding regimens were evaluated, including: i) feeding for 2 weeks, ii) feeding for 4 weeks, and iii) feeding every-other-week, with the objective of establishing the optimal feeding regimen that enhanced innate immunity and disease resistance. Innate immunity parameters were determined every week for eight weeks. Alternative complement activity of all β-glucan groups was significantly (P < 0.05) increased at the end of the first week, and then fluctuated but was not significantly (P > 0.05) different to the control until the end of the trial. Increased lysozyme activity was only detected at the end of the second week in all β-glucan-treated groups, and then decreased to the control level during most of the sampling periods. Phagocytosis percentage was increased and prolonged by β-glucan feeding, while the phagocytic index was not. Apart from innate immunity, β-glucan-fed fish demonstrated enhanced disease resistance against Aeromonas hydrophila and Flavobacterium columnare challenge at only the end of the fourth week of the trial. The growth performance of β-glucan-fed fish was not significantly (P > 0.05) different among the experimental groups and control. Taken together, the result indicated that all β-glucan-feeding regimens resulted in quite similar outcomes with respect to innate immunity stimulation, disease resistance and growth performance. This novel result suggests that an every-other-week regimen is the optimal choice for Nile tilapia cultivation as an economic cost saving benefit. This is the first study to determine the optimal feeding-regimen of β-glucan to enhance innate immunity and increase resistance to infection by pathogenic bacteria in Nile tilapia.

Topics: Aeromonas hydrophila; Animal Feed; Animals; Aquaculture; beta-Glucans; Cichlids; Diet; Disease Resistance; Fish Diseases; Flavobacteriaceae Infections; Flavobacterium; Gram-Negative Bacterial Infections; Immunity, Innate

β-Glucans are naturally occurring polysaccharides that are produced by bacteria, fungi and yeast. They are considered immunostimulants in fish acting on non-specific defense mechanism. Yeast-derived glucans from cell wall (Sterigmatomyces halophilus, β-Gluc/Sh) have been used for this purpose in this study. Therefore, an in vitro assay using peripheral blood leucocytes (PBLs) from Pacific red snapper was performed to evaluate the stimulant effects of β-Gluc/Sh and zymosan A (positive control) for 12 and 24 h and after bacterial challenge with Aeromonas hydrophila at 24 h. In addition, structural characterization of this marine yeast glucan was performed by proton nuclear magnetic resonance (NMR) revealing structures containing (1-6)-branched (1-3)-β-D-glucan. PBLs responded positively to β-Gluc/Sh where cell viability was higher than 80%. After challenge, β-Gluc/Sh was able to inhibit cytotoxicity caused by A. hydrophila, highlighting that the PBLs incubated with β-Gluc/Sh significantly increased the non-specific immune response, such as phagocytic activity, respiratory burst, nitric oxide and peroxidase activities followed by an increase in superoxide dismutase and catalase activities after 12 and 24 h post-stimulation and after challenge with the pathogen. Regarding induction of antioxidant gene expression, it was more pronounced in stimulated β-Gluc/Sh leucocytes compared to other groups at all experimental times of the trial and after bacterial challenge. Indeed, our results clearly showed the ability of leucocytes to strongly react to β-Gluc/Sh with an increase in cytokine gene expression, particularly the IL-1β, IL-10 and IL-17 genes. These results confirm that S. halophilus yeast-derived β-glucan, isolated from an extreme marine environment, is beneficial for increasing innate immune response and enhancing resistance against A. hydrophila in vitro.

Topics: Aeromonas hydrophila; Animal Feed; Animals; Basidiomycota; beta-Glucans; Diet; Dietary Supplements; Disease Resistance; Fish Diseases; Gram-Negative Bacterial Infections; Immunity, Innate; In Vitro Techniques; Leukocytes; Perciformes

Oligosaccharides from the water-soluble β-glucan, Salecan, were investigated to evaluate the activation effect on the defense responses of Arabidopsis thaliana Col0. Salecan oligosaccharides (ScOs, DP 5-10) were prepared at first by acid hydrolysis and gel filtration chromatography and then employed for foliar spray on Arabidopsis seedlings and plants. After ScOs treatment, increase of hydrogen peroxide was histologically and analytically detected in leaves. Transcription levels of several indicator genes which correspond to the signaling pathways and pathogenesis-related proteins were up-regulated at different time by means of quantitative RT-PCR analysis. Importantly, the sequential activation of salicylic acid-mediated and jasmonate-mediated signaling pathway was observed in leaves. Furthermore, pot test and antimicrobial test gave the fact that pretreatment with ScOs restrained the leaf lesions caused by infection of Botrytis cinerea Bc0510 via the enhancement of defense responses of A. thaliana. In conclusion, Salecan oligosaccharides serve as an elicitor which can be used for biological control of plant pathogen.

Topics: Arabidopsis; Arabidopsis Proteins; beta-Glucans; Botrytis; Disease Resistance; Gene Expression Regulation, Plant; Oligosaccharides; Plant Diseases; Plant Leaves; Seedlings

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.

Topics: Adjuvants, Immunologic; Aeromonas salmonicida; Animal Feed; Animals; beta-Glucans; Diet; Dietary Supplements; Disease Resistance; Dose-Response Relationship, Drug; Fish Diseases; Fish Proteins; Gram-Negative Bacterial Infections; Head Kidney; Immunity, Innate; Oncorhynchus mykiss; Random Allocation

Exposure of plants to UV-C irradiation induces gene expression and cellular responses that are commonly associated with wounding and pathogen defence, and in some cases can lead to increased resistance against pathogen infection. We examined, at a physiological, molecular and biochemical level, the effects of and responses to, sub-lethal UV-C exposure on Arabidopsis plants when irradiated with increasing dosages of UV-C radiation. Following UV-C exposure plants had reduced leaf areas over time, with the severity of reduction increasing with dosage. Severe morphological changes that included leaf glazing, bronzing and curling were found to occur in plants treated with the 1000 J·m(-2) dosage. Extensive damage to the mesophyll was observed, and cell death occurred in both a dosage- and time-dependent manner. Analysis of H₂O₂ activity and the pathogen defence marker genes PR1 and PDF1.2 demonstrated induction of these defence-related responses at each UV-C dosage tested. Interestingly, in response to UV-C irradiation the production of callose (β-1,3-glucan) was identified at all dosages examined. Together, these results show plant responses to UV-C irradiation at much lower doses than have previously been reported, and that there is potential for the use of UV-C as an inducer of plant defence.

Topics: Arabidopsis; Arabidopsis Proteins; beta-Glucans; Cell Death; Defensins; Disease Resistance; Gene Expression; Genes, Plant; Glucans; Hydrogen Peroxide; Plant Diseases; Plant Leaves; Ultraviolet Rays

Heterodera avenae (cereal cyst nematode, CCN) infects the roots of barley (Hordeum vulgare) forming syncytial feeding sites. In resistant host plants, relatively few females develop to maturity. Little is known about the physiological and biochemical changes induced during CCN infection. Responses to CCN infection were investigated in resistant (Rha2) and susceptible barley cultivars through histological, compositional and transcriptional analysis. Two phases were identified that influence CCN viability, including feeding site establishment and subsequent cyst maturation. Syncytial development progressed faster in the resistant cultivar Chebec than in the susceptible cultivar Skiff, and was accompanied by changes in cell wall polysaccharide abundance, particularly (1,3;1,4)-β-glucan. Transcriptional profiling identified several glycosyl transferase genes, including CELLULOSE SYNTHASE-LIKE F10 (HvCslF10), which may contribute to differences in polysaccharide abundance between resistant and susceptible cultivars. In barley, Rha2-mediated CCN resistance drives rapid deterioration of CCN feeding sites, specific changes in cell wall-related transcript abundance and changes in cell wall composition. During H. avenae infection, (1,3;1,4)-β-glucan may influence CCN feeding site development by limiting solute flow, similar to (1,3)-β-glucan during dicot cyst nematode infections. Dynamic transcriptional changes in uncharacterized HvCslF genes, possibly involved in (1,3;1,4)-β-glucan synthesis, suggest a role for these genes in the CCN infection process.

Topics: Animals; beta-Glucans; Cell Wall; Cluster Analysis; Crosses, Genetic; Disease Resistance; Disease Susceptibility; Fluorescence; Gene Expression Regulation, Plant; Genes, Plant; Giant Cells; Herbivory; Hordeum; Monosaccharides; Plant Diseases; Plant Proteins; Plant Roots; Polysaccharides; RNA, Messenger; Tylenchoidea

Grapevine (Vitis vinifera) is susceptible to many pathogens which cause significant losses to viticulture worldwide. Chemical control is available, but agro-ecological concerns have raised interest in alternative methods, especially in triggering plant immunity by elicitor treatments. The β-glucan laminarin (Lam) and its sulfated derivative (PS3) have been previously demonstrated to induce resistance in grapevine against downy mildew (Plasmopara viticola). However, if Lam elicits classical grapevine defenses such as oxidative burst, pathogenesis-related (PR)-proteins and phytoalexin production, PS3 triggered grapevine resistance via a poorly understood priming phenomenon. The aim of this study was to identify the molecular mechanisms of the PS3-induced resistance. For this purpose we studied i) the signaling events and transcriptome reprogramming triggered by PS3 treatment on uninfected grapevine, ii) grapevine immune responses primed by PS3 during P. viticola infection. Our results showed that i) PS3 was unable to elicit reactive oxygen species (ROS) production, cytosolic Ca(2+) concentration variations, mitogen-activated protein kinase (MAPK) activation but triggered a long lasting plasma membrane depolarization in grapevine cells, ii) PS3 and Lam shared a common stress-responsive transcriptome profile that partly overlapped the salicylate- (SA) and jasmonate-(JA)-dependent ones. After P. viticola inoculation, PS3 specifically primed the SA- and ROS-dependent defense pathways leading to grapevine induced resistance against this biotroph. Interestingly pharmacological approaches suggested that the plasma membrane depolarization and the downstream ROS production are key events of the PS3-induced resistance.

Topics: beta-Glucans; Cell Death; Cell Membrane; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Glucans; Oomycetes; Oxylipins; Plant Diseases; Plant Immunity; Reactive Oxygen Species; Salicylic Acid; Signal Transduction; Stress, Physiological; Transcriptome; Vitis

This study attempts to describe the effects of different administration periods of dietary β-glucan and Vit C on the non-specific immune response, physiological parameters and disease resistance of Nile tilapia against Aeromonas hydrophila infection. Therefore, a feeding trial (288 fish) was conducted to determine the best administration period (7, 15, 30 and 45 days) for a Nile tilapia diet supplemented with 0.1% β-glucan and 600 mg Vit C/kg diet. After the administration period, three different groups of 96 fish were exposed to one of the following three stresses: cold-induced stress, transport-induced stress, and A. hydrophila challenge. Hematological, biochemical and immunological responses were analyzed before and/or after stress. Cold-induced stress increased cortisol levels and reduced the leukocyte count in fish fed the test diet for seven days compared with the other periods. After transport-induced stress, fish fed the test diet for seven days required more hours to return to the baseline levels of cortisol and neutrophils. Moreover, independently of the administration period, fish needed 24 h for leukocyte and glucose levels to return to the initial values. The lowest survival after bacterial infection was observed in fish test diet for seven days. Based on fish hematological and biochemical responses, diet supplemented with 0.1% of β-glucan and 600 mg of Vit C/kg fed for at least 15 days is recommended for Nile tilapia especially when fish are likely to encounter transport-induced stress, and this stress was more severe than cold-induced stress or bacterial challenge.

Topics: Aeromonas hydrophila; Analysis of Variance; Animal Husbandry; Animals; Aquaculture; Ascorbic Acid; beta-Glucans; Brazil; Cichlids; Cold Temperature; Dietary Supplements; Disease Resistance; Fish Diseases; Gram-Negative Bacterial Infections; Stress, Physiological

Vascular plants possess multiple mechanisms for defending themselves against pathogens. One well-characterized defense mechanism is systemic acquired resistance (SAR). In SAR, a plant detects the presence of a pathogen and transmits a signal throughout the plant, inducing changes in the expression of various pathogenesis-related (PR) genes. Once SAR is established, the plant is capable of mounting rapid responses to subsequent pathogen attacks. SAR has been characterized in numerous angiosperm and gymnosperm species; however, despite several pieces of evidence suggesting SAR may also exist in non-vascular plants6-8, its presence in non-vascular plants has not been conclusively demonstrated, in part due to the lack of an appropriate culture system. Here, we describe and use a novel culture system to demonstrate that the moss species Amblystegium serpens does initiate a SAR-like reaction upon inoculation with Pythium irregulare, a common soil-borne oomycete. Infection of A. serpens gametophores by P. irregulare is characterized by localized cytoplasmic shrinkage within 34 h and chlorosis and necrosis within 7 d of inoculation. Within 24 h of a primary inoculation (induction), moss gametophores grown in culture became highly resistant to infection following subsequent inoculation (challenge) by the same pathogen. This increased resistance was a response to the pathogen itself and not to physical wounding. Treatment with β-1,3 glucan, a structural component of oomycete cell walls, was equally effective at triggering SAR. Our results demonstrate, for the first time, that this important defense mechanism exists in a non-vascular plant, and, together with previous studies, suggest that SAR arose prior to the divergence of vascular and non-vascular plants. In addition, this novel moss - pathogen culture system will be valuable for future characterization of the mechanism of SAR in moss, which is necessary for a better understanding of the evolutionary history of SAR in plants.

Topics: beta-Glucans; Bryopsida; Disease Resistance; Evolution, Molecular; Host-Pathogen Interactions; Plant Diseases; Pythium; Time Factors

Effects of β-glucan on innate immune responses and survival were studied in pacu experimentally infected with Aeromonas hydrophila. Fish fed diets containing 0, 0.1% and 1% β-glucan were injected with A. hydrophila. β-glucan enhanced fish survival in both treated groups (26.7% and 21.2% of the control, respectively). Leukocyte respiratory burst and alternative complement pathway activities were elevated after bacterial challenge regardless the β-glucan concentration. Lysozyme activity was higher after infection and showed a gradual increase as β-glucan concentration increased. A significant elevation in WBC count was observed either after bacterial challenge or by influence of β-glucan separately. The same response was observed in the number of thrombocytes, lymphocytes, eosinophils, LG-PAS positive cell and monocytes. It can be concluded that feeding pacu with β-glucan can increase protection against A. hydrophila, due to changes in non-specific immune responses.

Topics: Aeromonas hydrophila; Animal Feed; Animals; beta-Glucans; Disease Resistance; Fish Diseases; Gram-Negative Bacterial Infections; Survival Analysis

β-1,3-Glucan and chitin are the most prominent polysaccharides of the fungal cell wall. Covalently linked, these polymers form a scaffold that determines the form and properties of vegetative and pathogenic hyphae. While the role of chitin in plant infection is well understood, the role of β-1,3-glucan is unknown. We functionally characterized the β-1,3-glucan synthase gene GLS1 of the maize (Zea mays) pathogen Colletotrichum graminicola, employing RNA interference (RNAi), GLS1 overexpression, live-cell imaging, and aniline blue fluorochrome staining. This hemibiotroph sequentially differentiates a melanized appressorium on the cuticle and biotrophic and necrotrophic hyphae in its host. Massive β-1,3-glucan contents were detected in cell walls of appressoria and necrotrophic hyphae. Unexpectedly, GLS1 expression and β-1,3-glucan contents were drastically reduced during biotrophic development. In appressoria of RNAi strains, downregulation of β-1,3-glucan synthesis increased cell wall elasticity, and the appressoria exploded. While the shape of biotrophic hyphae was unaffected in RNAi strains, necrotrophic hyphae showed severe distortions. Constitutive expression of GLS1 led to exposure of β-1,3-glucan on biotrophic hyphae, massive induction of broad-spectrum defense responses, and significantly reduced disease symptom severity. Thus, while β-1,3-glucan synthesis is required for cell wall rigidity in appressoria and fast-growing necrotrophic hyphae, its rigorous downregulation during biotrophic development represents a strategy for evading β-glucan-triggered immunity.

Topics: beta-Glucans; Cell Wall; Colletotrichum; Disease Resistance; Echinocandins; Fungal Proteins; Gene Expression Profiling; Gene Expression Regulation, Fungal; Gene Expression Regulation, Plant; Genetic Complementation Test; Glucosyltransferases; Green Fluorescent Proteins; Host-Pathogen Interactions; Hyphae; Membrane Proteins; Microscopy, Fluorescence; Mutation; Oligonucleotide Array Sequence Analysis; Phylogeny; Plant Diseases; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Virulence; Zea mays

β-Glucans have been reported to be potent adjuvants in stimulating innate and adaptive immune responses. The aim of the present study was to determine the immunohematopoietic effects of Imunoglucan (HEBRON) following its oral administration to normal and Ehrlich ascites tumour (EAT)-bearing mice. Mice were treated with 250, 500 and 1000 mg/kg per day, p.o., Imunoglucan (β-1,3-glucan extracted from Saccharomyces cerevisae) for 18 consecutive days. Treatment started 10 days prior to and ended 8 days after tumour inoculation. At 500 and 1000 mg/kg per day, Imunoglucan enhanced the life span of EAT-bearing mice and prevented myelosuppression and splenomegaly caused by the tumour by increasing the number of granulocyte-macrophage progenitors in the bone marrow and increasing colony-stimulating activity in the serum. At 500 mg/kg, Imunoglucan restored the reduced ability of stromal cells to display myeloid progenitors in long-term bone marrow cultures of EAT-bearing mice and upregulated the production of interleukin (IL)-6 and IL-1α by these cells, consistent with a higher number of non-adherent cells. Moreover, 500 mg/kg Imunoglucan restored natural killer cell activity in tumour-bearing mice, consistent with the increased production of interferon (IFN)-γ observed. The results of the present study suggest that Imunoglucan given orally indirectly modulates immune activity and probably disengages tumour-induced suppression by producing a higher reserve of myeloid progenitors in the bone marrow in consequence of biologically active cytokine release (colony-stimulating factors, IL-1α, IL-6 and IFN-γ).

Topics: Administration, Oral; Animals; beta-Glucans; Carcinoma, Ehrlich Tumor; Cells, Cultured; Disease Resistance; Male; Mice; Mice, Inbred BALB C; Myeloid Progenitor Cells; Xenograft Model Antitumor Assays