Whitefly endosymbionts: IPM opportunity or tilting at windmills?

Whiteflies are sap-sucking insects responsible for high economic losses. They colonize hundreds of plant species and cause direct feeding damage and indirect damage through transmission of devastating viruses. Modern agriculture has seen a history of invasive whitefly species and populations that expand to novel regions, bringing along fierce viruses. Control efforts are hindered by fast virus transmission, insecticide-resistant populations, and a wide host range which permits large natural reservoirs for whiteflies. Augmentative biocontrol by parasitoids while effective in suppressing high population densities in greenhouses falls short when it comes to preventing virus transmission and is ineffective in the open field. A potential source of much needed novel control strategies lays within a diverse community of whitefly endosymbionts. The idea to exploit endosymbionts for whitefly control is as old as identification of these bacteria, yet it still has not come to fruition. We review where our knowledge stands on the aspects of whitefly endosymbiont evolution, biology, metabolism, multitrophic interactions, and population dynamics. We show how these insights are bringing us closer to the goal of better integrated pest management strategies. Combining most up to date understanding of whitefly-endosymbiont interactions and recent technological advances, we discuss possibilities of disrupting and manipulating whitefly endosymbionts, as well as using them for pest control.

BotRisk: simulating the annual bunch rot risk on grapevines (Vitis vinifera L. cv. Riesling) based on meteorological data.

The aim of the present investigations was to simulate the annual risk of bunch rot (Botrytis cinerea) on Vitis vinifera L. cv. Riesling grapes based on three long-term (n = 3 × 7 = 21 cases) assessment data sets originating from three Central European grape-growing regions. Periods when meteorological parameters were significantly (p < 0.01) correlated with the cumulative degree day (CDD7;18;24) reaching 5% disease severity were determined by Window Pane analysis. Analyses revealed five critical weather constellations ("events") influencing annual epidemics: relatively low temperatures after bud break, dry conditions during flowering, high temperatures after flowering, and low temperatures and high precipitation sums during/after veraison were all associated with thermal-temporal early epidemics. Meteorological data in each of the five events served as input for the bunch rot risk model "BotRisk." The multiple linear regression model resulted in an adjusted coefficient of determination (R2adj.) of 0.63. BotRisk enables (i) the simulation of the thermal-temporal position of the annual epidemic and, based on this, (ii) the classification of the annual bunch rot risk into three classes: low, medium, or high risk. According to leave-one-out cross-validation, 11 of 21 case studies were correctly classified. No systematic bias caused by location was observed, indicating that the transfer of the model into other locations with comparable climatic conditions could be possible. BotRisk (i) represents a novel viticultural decision support tool for crop cultural and chemical measures against bunch rot and (ii) enables an estimation of the bunch rot risk under changing environmental conditions.

Pesticide residue profiles in bee bread and pollen samples and the survival of honeybee colonies-a case study from Luxembourg.

Pesticide residues (112 compounds) were quantified by GC-MS/MS or LC-MS/MS in 85 bee bread samples and 154 pollen samples obtained from five apiaries each with three or four colonies (genotype Buckfast) in Luxembourg over the period 2011-2013. Thiacloprid, chlorfenvinphos, tebuconazole, and methiocarb were found most frequently in bee bread while thiacloprid, permethrin-cis, and permethrin-trans were detected most frequently in the pollen samples. Three neonicotinoid insecticides (clothianidin, imidacloprid, and thiamethoxam) that were restricted by an EU regulation in 2013 after our sampling campaign was finished were each found in less than 8% of the pollen or bee bread samples. The maximum concentrations of thiacloprid, metazachlor, and methiocarb measured in the pollen collected by a group of honeybee colonies (n = 5) without survivors within the 3-year period of observation were 86.20 ± 10.74 ng/g, 2.80 ± 1.26 ng/g, and below the limit of quantification, respectively. The maximum concentrations of the same compounds measured in the pollen collected by a group of honeybee colonies with significantly (P = 0.02) more survivors (7 out of 9) than expected, if the survivors had been distributed randomly among the groups of colonies, were 11.98 ± 2.28 ng/g, 0.44 ± 0.29 ng/g, and 8.49 ± 4.13 ng/g, respectively. No honeybee colony that gathered pollen containing more than 23 ng/g thiacloprid survived the 3-year project period. There was no statistically significant association between pesticide residues in the bee bread and the survival of the colonies. Actions already taken or planned and potential further actions to protect bees from exposure to pesticides are discussed.

Winter honey bee colony losses, Varroa destructor control strategies, and the role of weather conditions: Results from a survey among beekeepers.

Sets of treatments that were applied against varroa mites in the Luxembourgish beekeeper community were surveyed annually with a questionnaire between the winters 2010/11 and 2014/15. The average temperature and the precipitation sum of the month, when the respective varroa control method was applied were considered as co-variables when evaluating the efficacy of varroa control regimes. Success or failure of control regimes was evaluated based on the percentage of colonies lost per apiary in the winter following the treatment(s). Neither a positive nor a negative effect of formic acid (concentration 60%, w/v) on the colony losses could be found, irrespective of the weather conditions around the time of application. The higher concentration of 85% formic acid was linked with reduced colony losses when applications were done in August. Colony losses were reduced when Thymovar was applied in July or August, but applications in September were associated with increased losses compared with apiaries not treated with Thymovar during the same period. Apilife application in July as well as Apivar applications between July and September were associated with reduced colony losses. The removal of the drone brood and trickled oxalic acid application had beneficial effects when being done in April and December, respectively. Relatively warm (3.0±1.3°C) and wet (507.0±38.6mm/2months) conditions during the winter months December and January and relatively cool (17.2±1.4°C average monthly temperature) and wet (110.8±55.5mm/month) conditions in July were associated with elevated honey bee colony losses.

Magnesium affects spinach carotenoid bioaccessibility in vitro depending on intestinal bile and pancreatic enzyme concentrations.

Magnesium may reduce carotenoid bioavailability by forming insoluble complexes with bile salts/fatty acids, inhibiting micelle formation. Here, we investigated whether altering bile/pancreatin concentration influenced potential negative effects of magnesium on carotenoid bioaccessibility. Spinach (4g) was digested in vitro with added magnesium (0, 200, 400mg/L) and canola oil/coffee creamer, at varying bile extract (1 or 8mM) and pancreatin (100 or 990mg/L) concentrations. Bioaccessibility was determined for ß-carotene, lutein, and total carotenoids via HPLC. Additionally, lipolysis, particle size, and zeta potential of the micellar fractions were investigated. Increasing magnesium concentrations negatively affected carotenoid bioaccessibility (p<0.001), lipolysis, particle size and zeta potential. The impact of magnesium on carotenoid bioaccessibility was modulated mainly by bile concentration, with samples digested with 1mM of bile being more susceptible to inhibitory effects of magnesium than those digested with 8mM (p<0.001). Thus, magnesium was found to potentially interfere with carotenoid bioaccessibility at various physiologically plausible conditions.

Fate and effects of silver nanoparticles on early life-stage development of zebrafish (Danio rerio) in comparison to silver nitrate.

The use of silver nanomaterials in everyday products, such as cosmetics, textiles, certain types of packaging, etc. is increasing, leading to their release into the environment, including aquatic ecosystems. This last point initiated this investigation on the toxicological effects of Ag nanoparticles (Ag NPs) in the aquatic model organism Danio rerio. For this purpose, zebrafish larvae were exposed to 20nm bare Ag NPs at different concentrations and AgNO3, used as a positive control for Ag+ ions toxicity, at the beginning of their foraging behaviour to determine adverse effects on fitness parameters. We used secondary ion mass spectrometry (SIMS) to determine the localization of Ag and transcriptomics (microarray) to determine the toxicity at the level of gene expression in fish larvae. Exposure to Ag NPs did not result in adverse effects on survival and growth of the fish. However, SIMS analysis showed that Ag NPs mainly concentrate around liver blood vessels and in the interstitial tissue between the intestine and the liver. Gene expression profiles revealed that AgNO3 and Ag NPs impacted common pathways, suggesting similar targets, such as the phototransduction system. However, the Ag NPs showed a broader set of genes impacted following the exposure, including the circadian clock regulation and the photoreception, suggesting specific particle-related effects in addition to those induced by ions.

No influence of supplemental dietary calcium intake on the bioavailability of spinach carotenoids in humans.

Dietary carotenoid intake, especially from fruits and vegetables, has been associated with a reduced incidence of several chronic diseases. However, its bioavailability can vary, depending on the food matrix and host factors. Recently, it has been suggested that divalent minerals negatively impinge on carotenoid bioavailability by reducing bile-salt and non-esterified fatty-acid levels in the gut, which normally aid in emulsifying carotenoids. The aim of the present study was to investigate whether supplemental Ca would negatively influence carotenoid absorption in humans. A total of twenty-five healthy, non-obese men (age: 20-46 years, BMI<30 kg/m2) were recruited for this postprandial, randomised, crossover, double-blinded trial. Following a randomised block design, each participant received (after 2-week washout periods), on three occasions separated by 1 week, 270 g of spinach-based meals (8·61 (sd 1·08) mg carotenoids/100 g fresh weight), supplemented with 0, 500 or 1000 mg of Ca (as calcium carbonate), with each participant acting as his or her own control. Blood samples were collected at regular postprandial intervals for up to 10 h following test meal intake, and standardised lunches were served. TAG-rich lipoprotein fractions were separated and carotenoid concentrations determined. AUC for meals without supplemented Ca were 22·72 (sem 2·78) nmol×h/l (lutein), 0·19 (sem 3·90) nmol×h/l (ß-carotene) and 2·80 (sem 1·75) nmol×h/l (ß-cryptoxanthin). No significant influence of supplementation with either 500 or 1000 mg of supplemental Ca was found. In conclusion, Ca - the most abundant divalent mineral in the diet - given at high but physiological concentrations, does not appear to have repercussions on the bioavailability of carotenoids from a spinach-based meal.

Does kappa-carrageenan thermoreversible gelation affect ß-carotene oxidative degradation and bioaccessibility in o/w emulsions?

In the present work oil-in-gel (o/g) emulsions comprising 0.4-1% w/w κ-carrageenan in the absence and presence of Ca2+ (20mM) were investigated for their ability to hamper the oxidative degradation under isothermal (5, 20 and 37°C) ambient air storage conditions and promote the in vitro bioaccessibility of ß-carotene. The mechanical and structure conformational aspects of the o/g emulsions throughout in vitro digestion were measured by means of oscillatory rheology and optical microscopy. Although the addition of κ-carrageenan reduced by more than 50% (from 0.85 to 0.40day-1) the ß-carotene oxidative degradation rates, only minor differences were detected in terms of gelation method (ca. 0.42 and 0.39day-1 for ionotropic and coldset systems) and biopolymer concentration (0.38-0.42day-1). The bioaccessibility of ß-carotene was significantly higher in coldset o/g emulsions (ca. 43%) compared to the ionically mediated ones (ca. 36%). With the exception of 0.4% κ-carrageenan containing o/g emulsions (55.4 and 49.7% for control and 0.4% κ-carrageenan respectively), the ß-carotene bioaccessibility was significantly reduced with the increase in κ-carrageenan concentration (ranging from 34 to 38.9%).

Negative effects of divalent mineral cations on the bioaccessibility of carotenoids from plant food matrices and related physical properties of gastro-intestinal fluids.

Carotenoid intake and tissue levels have been frequently associated with reduced risk of chronic diseases. However, their bioavailability is low and influenced by many dietary related parameters. Divalent mineral cations have been suggested to interfere with carotenoid digestion and to hamper micellarization, a prerequisite for their uptake, via complexation of bile salts and precipitation of fatty acids. In the present investigation, we have evaluated the effects of increasing concentrations of magnesium (0-300 mg L-1), calcium (0-1500 mg L-1), zinc (0-200 mg L-1), and sodium (0-1500 mg L-1; control monovalent cation), on carotenoid bioaccessibility from frequently consumed food items rich in carotenoids (tomato juice, carrot juice, apricot nectar, spinach and field salad), following simulated gastro-intestinal digestion. In addition, physicochemical parameters of digesta (macroviscosity, surface tension), micelle size, and zeta-potential were evaluated. All divalent minerals (DM) reduced bioaccessibility of total carotenoids (P < 0.01), as well as of individual carotenoids. Calcium and magnesium led to reductions of up to 100% at the 2 highest concentrations. Curiously, sodium increased (P < 0.01) carotenoid bioaccessiblity of most investigated matrices. The absolute value of the zeta-potential decreased with increasing concentrations of DM, suggesting a decreased stability of the colloidal digesta dispersion. Viscosity decreased, except for apricot nectar samples, while surface tension increased with DM concentration (P < 0.05). Thus, at physiological ranges, calcium and magnesium could negatively impact carotenoid bioavailability, while for zinc, negative effects were only seen at supplemental concentrations. The potential negative effects of DM on carotenoid bioavailability should be further studied in vivo.

Modulation of chemical stability and in vitro bioaccessibility of beta-carotene loaded in kappa-carrageenan oil-in-gel emulsions.

In the present paper, ionotropically structured κ-carrageenan based oil-in-gel (o/g) emulsions were tested as potential carrier systems for the delivery of ß-carotene. In situ ionic gelation was induced by Na+, K+ or Ca2+ added at the level of 0.2-0.6% (w/w). All o/g emulsions exerted a true gel like behaviour with storage modulus (G') being reduced according to the order: K+>Ca2+>Na+. Ionic gelation induced a moderate increase in the microscopically assessed lipid droplets radii. O/g emulsions containing monovalent ions exerted the highest ß-carotene retention throughout isothermal storage particularly at high (37 and 55°C) temperatures. Notwithstanding, increasing ionic strength resulted in acceleration of ß-carotene degradation rates for all cation species. ß-Carotene bioaccessibility was significantly lower in Ca2+o/g emulsions due to the formation of complexes between the biopolymer matrix containing ß-carotene and bile salts. A good correlation between ß-carotene bioaccessibility, physical and colloidal aspects of the micellar digesta fractions was observed.

Proteomic response of inflammatory stimulated intestinal epithelial cells to in vitro digested plums and cabbages rich in carotenoids and polyphenols.

Due to their anti-oxidant and anti-inflammatory potential, polyphenol and carotenoid-rich plant foods have been suggested as promising phytochemicals in the prevention of or as adjuvants regarding inflammatory bowel diseases (IBD). In the present study, we investigated whether plum (Italian Plum, Prunus cocomilla), or cabbage (Kale, Brassica oleracea var. sabellica), selected for their high phytochemical content, are able to reduce inflammation in cellular models of the intestinal epithelium, employing proteomic methods. For this purpose, plum/cabbage (carotenoid content: 1.9 mg per 100 g resp. 13 mg per 100 g; polyphenol content: 83 mg per 100 g resp. 27 mg per 100 g) were gastro-intestinally digested, and aliquots exposed (18 h) to either a monoculture (Caco-2) or a triple culture (Caco-2/HT-29-MTX (90 : 10, v/v) with THP-1 like macrophages), stimulated (with LPS, TNF-α, and IL-1ß) to induce inflammation. Cells (Caco-2, Caco-2/HT-29-MTX, and THP-1) were then harvested separately, and proteomic analyses of total cell extracts were carried out by 2D-DIGE. In the monoculture, 68 protein-spots were significantly (p < 0.05, expression ratio >1.5) differentially regulated due to the Kale and Italian plum digesta, and in the co-culture 206 protein-spots, compared to digesta without plum/cabbage. These belonged to 27 (monoculture) and 76 (coculture) uniquely identified proteins, suggesting the coculture to be a more sensitive model. Proteins included antioxidant enzymes such as catalase, superoxide dismutase and glutathione-S-transferases. Only 3 proteins were differentially regulated in the THP-1 cells, perhaps as these were only indirectly exposed. The results show promise regarding some aspects related to IBD complications, however, employing phytochemical-rich food items should be further investigated in in vivo trials.

The Luxembourg database of trichothecene type B F. graminearum and F. culmorum producers.

Data specific to 486 strains belonging to Fusarium graminearum and Fusarium culmorum were manually collected from Luxembourg field monitoring campaigns between the year 2007 ad 2013. It is of interest to store such data in a web-enabled advanced database to help in epidemiological studies. Hence, we describe the design and development of a Fusarium database added to the Luxembourg Microbial Culture Collection (LuxMCC™) web interface at the Luxembourg Institute of Science and Technology (LIST). The database has three main features: (1) filter search, (2) detailed viewer of isolate information, and (3) excel export function of the dataset. Information on fungal strains includes genetic chemotypes, data on selected agronomic factors and crop management issues with geographic localization. The database constitutes a rich source of data for addressing epidemiological issues related to these two species. It will be regularly updated with improved features for advancement and utility.

A European Database of Fusarium graminearum and F. culmorum Trichothecene Genotypes.

Fusarium species, particularly Fusarium graminearum and F. culmorum, are the main cause of trichothecene type B contamination in cereals. Data on the distribution of Fusarium trichothecene genotypes in cereals in Europe are scattered in time and space. Furthermore, a common core set of related variables (sampling method, host cultivar, previous crop, etc.) that would allow more effective analysis of factors influencing the spatial and temporal population distribution, is lacking. Consequently, based on the available data, it is difficult to identify factors influencing chemotype distribution and spread at the European level. Here we describe the results of a collaborative integrated work which aims (1) to characterize the trichothecene genotypes of strains from three Fusarium species, collected over the period 2000-2013 and (2) to enhance the standardization of epidemiological data collection. Information on host plant, country of origin, sampling location, year of sampling and previous crop of 1147 F. graminearum, 479 F. culmorum, and 3 F. cortaderiae strains obtained from 17 European countries was compiled and a map of trichothecene type B genotype distribution was plotted for each species. All information on the strains was collected in a freely accessible and updatable database (www.catalogueeu.luxmcc.lu), which will serve as a starting point for epidemiological analysis of potential spatial and temporal trichothecene genotype shifts in Europe. The analysis of the currently available European dataset showed that in F. graminearum, the predominant genotype was 15-acetyldeoxynivalenol (15-ADON) (82.9%), followed by 3-acetyldeoxynivalenol (3-ADON) (13.6%), and nivalenol (NIV) (3.5%). In F. culmorum, the prevalent genotype was 3-ADON (59.9%), while the NIV genotype accounted for the remaining 40.1%. Both, geographical and temporal patterns of trichothecene genotypes distribution were identified.

Inflammation related responses of intestinal cells to plum and cabbage digesta with differential carotenoid and polyphenol profiles following simulated gastrointestinal digestion.

SCOPE: Plums/cabbages represent fruits/vegetables rich in carotenoids and polyphenols, and have been associated with anti-inflammatory properties. METHODS AND RESULTS: We tested four plum (Italian Plum, Plum 620, Ersinger, and Cherry Plum) and cabbage varieties (Duchy, Kalorama, Kale, Scots Kale) with contrasting carotenoid/polyphenol content for their capability to alter inflammation/oxidative stress following simulated gastrointestinal digestion. Digesta were exposed to Caco-2(TC-7) and to a triple-culture(Caco-2/HT-29-MTX (90:10 v/v) including THP-1 like macrophages), stimulated to induce inflammation (10 µg/mL LPS, 100 ng/mL TNF-α, 25 ng/mL IL-1-ß for 24 h, the last 18 h with digesta). Endpoints investigated included IL-6, IL-8, PGE-2, NO (all ELISA), NF-κB, MAPK, IL-6, IL-8, iNOS, Nrf2, COX-2 (real-time-PCR) and Nrf2 (immunostaining). IL-6 secretion was reduced in THP-1 cells by Scots Kale and Kalorama (up to 22%, p<0.05), and IL-8 secretion in the coculture (up to 35% in plums, p<0.05). This was accompanied by decreased NF-kB expressions in THP-1 cells (up to 30%, p<0.05). Nrf2 translocation to the nucleus was partly reduced by plums and cabbages (up to 40% (p<0.05). CONCLUSIONS: Some varieties, especially in the triple-culture, reduced inflammation, though this was unrelated to concentrations of carotenoids/polyphenols. The potential of phytochemical-rich fruits and vegetables to ameliorate gastrointestinal inflammation should be further investigated.

2-D DIGE proteomic profiles of three strains of Fusarium graminearum grown in agmatine or glutamic acid medium.

2D DIGE proteomics data obtained from three strains belonging to Fusarium graminearum s.s. species growing in a glutamic acid or agmatine containing medium are provided. A total of 381 protein species have been identified which do differ for abundance among the two treatments and among the strains (ANOVA<0.05 and abundance ratio>±1.3). Data on the diversity of protein species profiles between the two media for each strain are made available. Shared profiles among strains are discussed in Pasquali et al. [1]. Here proteins that with diverse profile can be used to differentiate strains are highlighted. The full dataset allow to obtaining single strain proteomic profiles.

Study of intragastric structuring ability of sodium alginate based o/w emulsions under in vitro physiological pre-absorptive digestion conditions.

In the present work, the intragastric structuring ability of o/w emulsions either stabilised (1-4%, w/w of sodium alginate (SA)) or structured with sheared ionic gel (1-3%, w/w of SA crosslinked with Ca(2+)) in the absence (saliva and gastric phases constituted of deionised water) or presence of in vitro pre-absorptive conditions (physiological simulated saliva and gastric fluids) was investigated. Visualisation of the morphological aspects of the gastric chymes, in the absence of multivalent counterions, demonstrated that SA stabilised systems underwent a remarkable swelling in the pH range of 2-3, whilst at the same pH range, ionic SA gel structured systems maintained their major structure configuration. When the aforementioned systems were exposed to physiological intragastric fluids, a reduction of the length and the hydrodynamic volume of the alginate fibres was detected regardless the structuring approach. On their exposure to physiological intragastric conditions (pH=2), SA stabilised emulsions underwent sol-gel transition achieving a ca. 3- to 4-order increase of storage modulus (at 1Hz). In the case of ionic sheared gel structured emulsions, exposure to physiological intragastric fluids resulted in a 10-fold reduction ability of their acid structuring ability, most likely due to the dialysis of egg-box dimer conformations by monovalent cations and protons and the sterical hindering of hydrogen bonding of MM and GG sequences under acidic conditions. Using of non-physiological simulated intragastric fluids was associated with overestimated structuring performance of SA regardless its physical state.

Effects of silver nanoparticles and ions on a co-culture model for the gastrointestinal epithelium.

BACKGROUND: The increased incorporation of silver nanoparticles (Ag NPs) into consumer products makes the characterization of potential risk for humans and other organisms essential. The oral route is an important uptake route for NPs, therefore the study of the gastrointestinal tract in respect to NP uptake and toxicity is very timely. The aim of the present study was to evaluate the effects of Ag NPs and ions on a Caco-2/TC7:HT29-MTX intestinal co-culture model with mucus secretion, which constitutes an important protective barrier to exogenous agents in vivo and may strongly influence particle uptake. METHODS: The presence of the mucus layer was confirmed with staining techniques (alcian blue and toluidine blue). Mono and co-cultures of Caco-2/TC7 and HT29-MTX cells were exposed to Ag NPs (Ag 20 and 200 nm) and AgNO3 and viability (alamar blue), ROS induction (DCFH-DA assay) and IL-8 release (ELISA) were measured. The particle agglomeration in the media was evaluated with DLS and the ion release with ultrafiltration and ICP-MS. The effects of the Ag NPs and AgNO3 on cells in co-culture were studied at a proteome level with two-dimensional difference in gel electrophoresis (2D-DIGE) followed by Matrix Assisted Laser Desorption Ionization - Time Of Flight/ Time Of Flight (MALDI-TOF/TOF) mass spectrometry (MS). Intracellular localization was assessed with NanoSIMS and TEM. RESULTS: The presence of mucus layer led to protection against ROS and decrease in IL-8 release. Both Ag 20 and 200 nm NPs were taken up by the cells and Ag NPs 20 nm were mainly localized in organelles with high sulfur content. A dose- and size-dependent increase in IL-8 release was observed with a lack of cytotoxicity and oxidative stress. Sixty one differentially abundant proteins were identified involved in cytoskeleton arrangement and cell cycle, oxidative stress, apoptosis, metabolism/detoxification and stress. CONCLUSIONS: The presence of mucus layer had an impact on modulating the induced toxicity of NPs. NP-specific effects were observed for uptake, pro-inflammatory response and changes at the proteome level. The low level of overlap between differentially abundant proteins observed in both Ag NPs and AgNO3 treated co-culture suggests size-dependent responses that cannot only be attributed to soluble Ag.

The effect of agmatine on trichothecene type B and zearalenone production in Fusarium graminearum, F. culmorum and F. poae.

Agmatine and other putrescines are known for being strong inducers of deoxynivalenol (DON) production in Fusarium graminearum. Other important species produce DON and/or other trichothecene type B toxins (3 acetylated DON, 15 acetylated DON, Fusarenon-X, Nivalenol), such as F. culmorum and F. poae. In order to verify whether the mechanism of the regulation of trichothecene type B induction by agmatine is shared by different species of Fusarium, we tested the hypothesis on 19 strains belonging to 3 Fusarium species (F. graminearum, F. culmorum, F. poae) with diverse genetic chemotypes (3ADON, 15ADON, NIV) by measuring trichothecene B toxins such as DON, NIV, Fusarenon-X, 3ADON and 15ADON. Moreover, we tested whether other toxins like zearalenone were also boosted by agmatine. The trichothecene type B boosting effect was observed in the majority of strains (13 out of 19) in all the three species. Representative strains from all three genetic chemotypes were able to boost toxin production after agmatine treatment. We identified the non-responding strains to the agmatine stimulus, which may contribute to deciphering the regulatory mechanisms that link toxin production to agmatine (and, more generally, polyamines).

Carotenoid and polyphenol bioaccessibility and cellular uptake from plum and cabbage varieties.

Plum and cabbage are rich in carotenoids and polyphenols. However, their bioactivity depends on their release and intestinal uptake. Four varieties of Brassicaceae (Duchy, Scots Kale, Kale, Kalorama) and Prunus (Cherry Plum, Plum 620, Ersinger, Italian Plum) were studied; bioaccessibility following in vitro digestion, cellular uptake (Caco-2 vs. co-culture cell model: Caco-2:HT-29-MTX (90:10%) and colonic fermentation were determined for carotenoids/polyphenols; the influence of certain kitchen preparations was likewise studied. Carotenoids were non-significantly influenced by the latter, while for polyphenols, boiling and steaming significantly reduced total phenolics (p<0.05). Carotenoid bioaccessibility did not differ significantly between Prunus vs. Brassicaceae varieties, but xanthophyll was higher than carotene bioaccessibility (p<0.01). Polyphenol bioaccessibility was low (<10%), possibly compromised by the cream containing test meal. Total carotenoid cellular uptake varied between varieties (0.3-4.1%), being higher for carotenes (4.1%) than for xanthophylls (1.6%, p<0.01), and were higher for the co-culture cell model compared to Caco-2 cells (p<0.01). Total carotenoid recovery in the colonic fraction varied from 4% to 25%. Lower bioaccessibility of carotenes thus appeared to be somewhat counterbalanced by higher cellular uptake. The potential positive role of the mucus layer for cellular uptake and the fate of the colonic digesta deserve further attention in the future.

Effect of divalent minerals on the bioaccessibility of pure carotenoids and on physical properties of gastro-intestinal fluids.

During digestion, high concentrations of divalent minerals (DMs) can lead to insoluble lipid-soap complex formation, hampering carotenoid bioaccessibility. The effect of varying concentrations (0-1000 mg/L) of calcium, magnesium, zinc and sodium (control) on the bioaccessibility of lutein, neoxanthin, lycopene and ß-carotene, following in vitro gastro-intestinal digestion (GI), was investigated systematically and coupled with physical measurements of the digesta. Addition of DMs significantly decreased (p<0.001) carotenoid bioaccessibility, up to 100% in the case of calcium. Mean half maximal inhibitory concentrations (EC50) for calcium, magnesium and zinc were 270±18, 253±75 and 420±322 mg/L respectively. Increased DM concentrations correlated with decreased viscosity (r>0.9) and decreased carotenoid bioaccessibility. Surface tension of digesta correlated inversely (p<0.05) with the bioaccessibility of carotenoids. This correlation was mineral and carotenoid dependent. Although based on in vitro findings, it is plausible that similar interactions occur in vivo, with DMs affecting the bioaccessibility and bioavailability of carotenoids and other lipophilic micronutrients and phytochemicals.