Enzymatic reactions by five chalcone synthase homologs from hop (Humulus lupulus L.).
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The enzyme activities encoded in five cDNAs for chalcone synthase (CHS) homologs from hop were investigated. Only valerophenone synthase (VPS) and CHS_H1 showed both naringenin-chalcone and phlorisovalerophenone forming activity. Narigenin-chalcone production by VPS was much lower than by CHS_H1. Therefore, it is highly possible that flavonoid depends mainly on CHS_H1, while bitter acid biosynthesis depends mainly on VPS and CHS_H1. (+info)
Isohumulones, bitter acids derived from hops, activate both peroxisome proliferator-activated receptor alpha and gamma and reduce insulin resistance.
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The peroxisome proliferator-activated receptors (PPARs) are dietary lipid sensors that regulate fatty acid and carbohydrate metabolism. The hypolipidemic effects of fibrate drugs and the therapeutic benefits of the thiazolidinedione drugs are due to their activation of PPARalpha and -gamma, respectively. In this study, isohumulones, the bitter compounds derived from hops that are present in beer, were found to activate PPARalpha and -gamma in transient co-transfection studies. Among the three major isohumulone homologs, isohumulone and isocohumulone were found to activate PPARalpha and -gamma. Diabetic KK-Ay mice that were treated with isohumulones (isohumulone and isocohumulone) showed reduced plasma glucose, triglyceride, and free fatty acid levels (65.3, 62.6, and 73.1%, respectively, for isohumulone); similar reductions were found following treatment with the thiazolidinedione drug, pioglitazone. Isohumulone treatment did not result in significant body weight gain, although pioglitazone treatment did increase body weight (10.6% increase versus control group). C57BL/6N mice fed a high fat diet that were treated with isohumulones showed improved glucose tolerance and reduced insulin resistance. Furthermore, these animals showed increased liver fatty acid oxidation and a decrease in size and an increase in apoptosis of their hypertrophic adipocytes. A double-blind, placebo-controlled pilot study for studying the effect of isohumulones on diabetes suggested that isohumulones significantly decreased blood glucose and hemoglobin A1c levels after 8 weeks (by 10.1 and 6.4%, respectively, versus week 0). These results suggest that isohumulones can improve insulin sensitivity in high fat diet-fed mice with insulin resistance and in patients with type 2 diabetes. (+info)
Exposure of hop growers to bioaerosols.
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Air sampling was performed during picking and sorting of hop (Humulus lupulus) cones on 19 hop farms located in eastern Poland. The concentration and composition of airborne microflora and the concentration of airborne dust and endotoxin were determined. Additionally, 7 samples of settled hop dust were collected and examined for the presence of microorganisms and endotoxin. Total concentrations of airborne microorganisms were within a range of 2.08-129.58 x 10(3) cfu/m(3). Gram-positive bacteria formed 22.2-96 % of the total count. Among them, prevailed corynebacteria and endospore-forming bacilli. Fungi constituted 3.7-65.4 % of the total count. The dominant species were Penicillium citrinum, Alternaria alternata, and Cladosporium epiphyllum. Thermophilic actinomycetes and Gram-negative bacteria were detected in the air of only 10 and 6 farms, respectively. Airborne dust concentrations at the workplace ranged from 0.17-31.67 mg/m(3). The concentrations of airborne endotoxin were in the range of 26-6250 ng/m(3). In the samples of settled dust, the concentrations of total microorganisms ranged from 0.25 x 10(6) to 2.87 x 10(8) cfu/g. Gram-positive and Gram-negative bacteria constituted respectively 3.2-98 % and 0-93.5 % of the total count. Fungi formed 0-30.3 % of the total count. The most common species were Penicillium spp. and Alternaria alternata. The concentrations of endotoxin were in the range of 312.5-6250 microg/g (median 6250 microg/g). The presence of microorganisms and endotoxin in the samples of settled dust was confirmed by electron microscopy. The hop growers seem to be exposed to lower concentrations of dust, microorganisms and endotoxin compared to other branches of agriculture. This may be partly due to antimicrobial properties of hop plant. Among microbial factors associated with hop dust, bacterial endotoxin and allergenic fungi pose the greatest potential hazard for exposed hop farmers. (+info)
Managing the evolution of Bacillus thuringiensis resistance in natural populations of the European corn borer, Ostrinia nubilalis: host plant, host race and pherotype of adult males at aggregation sites.
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The European corn borer (ECB) consists of at least two, genetically differentiated host races: one feeding on maize, the other feeding on mugwort and hop. It is unclear to what extent individuals feeding on these, or other host plants, contribute to natural ECB populations. The mechanisms underlying the genetic differentiation between both races are not well understood; they may include sexual attraction via different pheromone blends (E or Z) and differences in the location of mating sites. We caught adult males with traps baited with the E or the Z blend at hop, maize, and 'mixed' sites. We determined their probable host race by allozyme-based genetic assignment, and the photosynthetic type of their host plant by stable carbon isotope analysis. Most individuals caught in Z traps had emerged from a C(4)-type plant and belonged to the maize race, whereas most individuals caught in E traps had emerged from C(3)-type plants and were but weakly differentiated from the hop-mugwort race, suggesting a strong, though not absolute, correspondence between host plant, host race and pherotype. We also found that although spatial segregation may contribute to genetic isolation between host races, moths of both host races may be present at a given location. Regarding the management of Bacillus thuringiensis (Bt) maize, our results indicate that, at least at the present study sites, it is unlikely that any wild or cultivated C(3)-type plant species could be a source of susceptible individuals that would mate randomly with Bt-resistant Z-C(4) moths emerging from Bt-maize fields. (+info)
Genetic isolation between two sympatric host plant races of the European corn borer, Ostrinia nubilalis Hubner. II: assortative mating and host-plant preferences for oviposition.
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The European corn borer, Ostrinia nubilalis Hubner, colonized maize (Zea mays L.) after its introduction into Europe about 500 years ago and is now considered one of the main pests of this crop. In northern France, two sympatric host races have been described: one feeding on maize and the other on mugwort (Artemisia vulgaris L.) and hop (Humulus lupulus L.). In a previous study, we showed that mating between the two races may be impeded by differences in the timing of moth emergence and in the composition of the sex pheromone produced by the females. In this study, we further investigated the genetic isolation of these two races using strains from the maize (Z strain) and mugwort (E strain) races selected for diagnostic alleles at two allozyme loci. In a cage containing maize and mugwort plants and located in natural conditions, mating between individuals of the same strain occurred more often than mating between males and females of the E and Z strains. In particular, we obtained no evidence for crosses between Z females and E males. We also found that females of the Z strain laid their eggs almost exclusively on maize, whereas females of the E strain laid their eggs preferentially, but not exclusively, on mugwort. These results suggest that the genetic differentiation between the two host races may also be favored by host-plant preference, one of the first steps toward sympatric speciation. (+info)
Selected parameters of immunological response in hop growers during the period of intensive application of pesticides.
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The aim of the study was determination of selected parameters of immunological response among hop growers and farmers in conditions of intensive exposure to means of plant protection. Survey data was collected from 238 males aged 25-70 living in the area of Wilkow near Pulawy (Lublin Region). Control group were males from the area of Witoszyn (Lublin Region)--53 people aged 25-70 occupied mainly with land cultivation. Based on an environmental survey conducted among hop growers and farmers, the respondents were divided into 3 age groups: 25-40, 41-55 and 56-70. Laboratory tests covered the determination of selected morphological parameters, phagocytic test, NBT test, and myeloperoxidasis (MPO) concentration in blood serum of hop growers and farmers.A significant decrease was noted in the number of platelets in the general population of hop growers and in individual age groups, compared to the control groups of farmers. Analysis of individual sub-populations of leukocytes showed a significantly higher number statistically of basophils and lymphocytes among hop growers, compared to farmers. A detailed analysis of the degree of phagocytic and bactericidal activity of neutrophils allowed us to presume that during the period of spraying there occurred a mobilisation of the granulocytic system, manifested by the presence of over 90% of neutrophils of intensified phagocytic activity, and 20% of neutrophils of intensified bactericidal activity. The preparations prepared by the routine NBT test method were analysed with the use of LUCIA computer programme (version 4.51). The analysis of the level of MPO in blood serum in the populations examined showed the presence of statistically significant differences. In hop growers, the MPO level was significantly higher statistically (60.0 ng/ml), compared to the control group of farmers (43.4 ng/ml). (+info)
Effect of humulus lupulus on gastric secretion in a rat pylorus-ligated model.
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In this study, we investigated the pharmacological effect of humulus lupulus (hops) on gastric juice volume and acidity using a rat pylorus-ligated model. In an intraorally administered experiment, hops clearly increased gastric juice volume without affecting acidity. On the other hand, hops had no influence on gastric juice volume when it was intragastrically administered. A cholinergic agonist, carbachol, increased gastric juice volume without affecting acidity, whereas histamine increased gastric juice volume and acidity. The increase of gastric juice volume induced by carbachol was completely inhibited by atropine. On the other hand, atropine did not inhibit the increase in gastric juice volume induced by histamine. The increase in gastric juice volume induced by hops was completely inhibited by atropine. These results suggested that the increase in gastric juice volume induced by intraorally administered hops could be mediated by the cholinergic nervous system. (+info)
Differential activities of plant polyphenols on the binding and internalization of cholera toxin in vero cells.
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Plant polyphenols, RG-tannin, and applephenon had been reported to inhibit cholera toxin (CT) ADP-ribosyltransferase activity and CT-induced fluid accumulation in mouse ileal loops. A high molecular weight fraction of hop bract extract (HBT) also inhibited CT ADP-ribosyltransferase activity. We report here the effect of those polyphenols on the binding and entry of CT into Vero cells. Binding of CT to Vero cells or to ganglioside GM1, a CT receptor, was inhibited in a concentration-dependent manner by HBT and applephenon but not RG-tannin. These observations were confirmed by fluorescence microscopy using Cy3-labeled CT. Following toxin binding to cells, applephenon, HBT, and RG-tannin suppressed its internalization. HBT or applephenon precipitated CT, CTA, and CTB from solution, creating aggregates larger than 250 kDa. In contrast, RG-tannin precipitated CT poorly; it formed complexes with CT, CTA, or CTB, which were demonstrated with sucrose density gradient centrifugation and molecular weight exclusion filters. In agreement, CTA blocked the inhibition of CT internalization by RG-tannin. These data suggest that some plant polyphenols, similar to applephenon and HBT, bind CT, forming large aggregates in solution or, perhaps, on the cell surface and thereby suppress CT binding and internalization. In contrast, RG-tannin binding to CT did not interfere with its binding to Vero cells or GM1, but it did inhibit internalization. (+info)