Contents of lovastatin, γ-aminobutyric acid and ergothioneine in mushroom fruiting bodies and mycelia

Lovastatin, γ-aminobutyric acid (GABA) and ergothioneine were analysed in mushrooms. Among fruiting bodies, Pleurotus ostreatus (Japan) and Agaricus bisporus contained the highest amount of lovastatin (606.5 and 565.4 mg/kg, respectively) whereas among mycelia, Cordyceps sinensis and Antrodia salmonea contained the highest (1365 and 1032 mg/kg, respectively). Among fruiting bodies, Flammulina velutipes and Boletus edulis contained the highest amount of GABA (229.7 and 202.1 mg/kg, respectively) whereas among mycelia, Cordyceps cicadae, C. sinensis and Agaricus blazei contained the highest (254.9, 220.5 and 200.4 mg/kg, respectively). Among fruiting bodies, Pleurotus citrinopileatus, P. ostreatus (Korea), P. ostreatus (Taiwan) and Pleurotus salmoneostramineus contained the highest amount of ergothioneine (2850.7, 1829.4, 1458.4 and 1245.0 mg/kg, respectively) whereas among mycelia, Pleurotus eryngii contained the highest (1514.6 mg/kg). Ergothioneine was detected in all samples. However, the Pleurotus genus contained considerably high amount of ergothioneine. Overall, these results might be related to their beneficial effects.     

Rapid purification and characterization of γ-glutamyl-transpeptidase from shiitake mushroom (Lentinus edodes)

γ-Glutamyl-transpeptidase (GGT) is one of the important enzymes in the pathway of odor formation in shiitake mushroom (Lentinus edodes). Rapid purification and characterization of GGT from shiitake mushroom were studied in this work. The GGT was purified 179-fold after 3 primary steps: precipitation by ammonium sulfate, isolation by Phenyl Sepharose 6 FF, and desalting by Sephadex G-25. The enzyme, consisting of a small and a large subunit with Mr 28 KDa and 60 KDa, respectively, is composed of 17 kinds of amino acids with the ratio of basic and acidic residues 1 : 1.84, and its secondary structure was also determined by Fourier transform infrared spectroscopy. The properties of GGT were studied with γ-glutamyl-p-nitroanilide as the substrate. The results showed Km value of 2.601 μM, optimal temperature of 40 °C, and isoelectric point of 6.4. In addition, the activity of GGT was promoted by Na(+), K(+), and Ca(2+) and inhibited by Cu(2+), Ag(+), Zn(2+), and Fe(3+). PRACTICAL APPLICATION: In this work, the γ-glutamyl-transpeptidase (GGT) from shiitake mushroom was purified with a simple scheme. Through the characterization of GGT, the relationship between endogenous formaldehyde and odor formation is to be clarified and assist in finding means of formaldehyde control in shiitake mushroom.     

Concentrations of dioxins and dioxin-like PCBs in feed materials in the Netherlands, 2001–11

This study aimed to obtain insights into contamination of feed materials used in the Netherlands with dioxins (polychlorinated dibenzo-p-dioxins and dibenzofurans) and dioxin-like polychlorinated biphenyls (PCBs). Monitoring results from the period 2001–11, covering in total 4938 samples, were statistically analysed and evaluated against the statutory limits set at the beginning or during this period. The percentage of samples exceeding maximum levels set within the European Union for either dioxins or the sum of dioxins and dioxin-like PCBs were below 1% for most feed categories, except for fish meal (4.1%), clay minerals (binders and anti-caking agents) (3.4%), and vegetable oils and byproducts (1.7%). For most feed categories, non-compliance with the action threshold (roughly 33% lower than maximum levels) for either dioxins or dioxin-like PCBs was up to three times higher than non-compliance with the respective maximum levels. Exceedance of action thresholds was just above 1% for animal fat, pre-mixtures and feed materials of plant origin excluding vegetable oils. For the categories fish meal, clay minerals, and vegetable oils and byproducts, the action thresholds were exceeded by 5.0%, 9.8% and 3.0% of the samples, respectively. In general, the percentages of samples that exceeded the action thresholds and maximum levels were lower than those reported for the European Union by the European Food Safety Authority (EFSA). In most of the feed materials, there seems to be a decreasing trend in concentrations of dioxins or dioxin-like PCBs over the years. However, a lowering of the limits of quantification during this period and the low concentrations in most samples precludes drawing strong conclusions.     

Intra- and interspecies variation in bioconcentration potential of polychlorinated biphenyls: are all lipids equal?

The variation among bioconcentration factors (BCFs) available in the literature is commonly ascribed to experimental parameters and metabolic capacity. Though bioconcentration is generally considered to be governed by partitioning processes and therefore to depend on the composition of the partition phases, the effect of lipid composition on BCFs measured for hydrophobic organic chemicals has largely escaped attention. The reason may be that the effect cannot easily be studied separately in a conventional BCF test setup and that any subtle effects will often be obscured by the variation normally observed when working with living organisms. In the present study, this variation was circumvented by substituting biota with biological homogenates, which allowed measuring chemical partitioning in a fashion that has proved successful for many other environmental matrixes (e.g., sediments, soils, carbonaceous materials). The appropriateness of using a homogenate as a representation of the organism from which it was derived was demonstrated by a good agreement between homogenate-water partition coefficients (or necroconcentration factors; NCFs) and actual BCFs for PCBs and aquatic worms. Subsequent experiments focused on the intra- and interspecies differences in lipid-normalized NCFs. Intraspecies variation was studied for aquatic worms and sticklebacks, which were acclimatized at different temperatures (5-24 °C), whereas interspecies variation was investigated by determining NCFs for eight different aquatic species. Although temperature-induced intraspecies differences were subtle (<0.16 log units), interspecies differences among lipid-normalized NCFs were as high as 0.9 log units, with homogenates of "simple" organisms showing a lower sorption capacity than those of the more "complex" species. These results suggest that the variation observed in the literature BCFs may partly be caused by differences in lipid composition and contest the usefulness of the common practice of applying generic BCFs in risk assessment of chemicals.     

Purification, chemical characterization, and antioxidant activity of a polysaccharide from the fruiting bodies of sanghuang mushroom (Phellinus baumii Pilát)

A purified water-soluble polysaccharide was isolated from the fruiting bodies of sanghuang mushroom (Phellinus baumii Pilát) using hot water extraction, DEAE Sepharose Fast Flow anion exchange and High-Resolution Sephacryl S-1000 gel-filtration chromatography. The purified polysaccharide was a complex β-d-glucan, with a molecular mass of 230 kDa. Fourier-transform infrared (FT-IR), methylation analysis, and NMR spectroscopy of sanghuang mushroom polysaccharide (PBF3) indicated that the polysaccharide contained (1→3)-β-d-, (1→4)-β-d-, and branched (1→3,6)-β-d-glucopyranosyl residues. On the basis of hydroxyl radical assay, superoxide radical assay, and DPPH radical assay, its antioxidant activities were investigated. PBF3 had significant effect on scavenging hydroxyl radicals, an equivalent inhibiting ability to vitamin C on superoxide radical, and a little lower scavenging activity on DPPH radical than vitamin C, and should be explored as a novel potential antioxidant.     

Cheers,proost, saúde: Cultural,contextual and psychological factors of wine and beer consumption in Portugal and in the Netherlands

Wine and beer consumption are an integral part of European culture: Southern Europe is associated with wine and Northern Europe is associated with beer. When consumed in moderation, these alcoholic beverages can be part of a balanced and healthy diet. In the 1990s, non-alcoholic beer (NAB), which has no cultural roots, became available in the market. This review identifies determinants for consumption of wine, beer, and NAB, using data on consumption patterns from Portugal and the Netherlands. Since the 1960s the image of Portugal as a wine country declined, whereas the image of the Netherlands as a beer country remained stable. In each country beer is now the most consumed alcoholic beverage and is mainly a men's beverage, whereas wine is the second most consumed and is consumed by both genders. Cultural differences define Portuguese as “outdoors, everyday drinkers”, within a meal context, and Dutch as “at home, weekend drinkers.” Wine is perceived as the healthiest beverage, followed by NAB, and regular beer. Motivation for consumption is related to context: wine for special occasions, beer for informal occasions, and NAB for occasions when alcohol is not convenient. Moderate wine and beer consumption seems to be surrounded by positive emotions.

This review is relevant for public health, for industry market strategies, and identifies opportunities of future research on drinking behaviour.     

Impact of selected factors – Cultivar,storage, cooking and baking on the content of anthocyanins in coloured-flesh potatoes

The impact of selected factors – cultivar, storage, cooking and baking on the content of total anthocyanins (TAC) in coloured-flesh potato cultivars has been studied. TAC ranged from 248.5 to 2257.8 mg kg⁻¹ dry matter (DM). TAC difference between cultivars was statistically significant. Cold storage (4 °C) influenced TAC differentially. In the Violette and Highland Burgundy Red cultivars TAC increased by 18.5% and 12.1% respectively, and in the Valfi cultivar it decreased by 33.9%. Baking increased TAC 3.34 times whereas cooking in boiled water increased it 4.22 times. Correlation between antioxidant activity (AOA) and TAC (r² = 0.659) has been found. The Violette, Vitelotte and Highland Burgundy Red cultivars with the highest TAC showed high AOA and the Shetland Black cultivar and the cultivars Salad Blue and Blue Congo with a “marbled” texture showed the lowest TAC and AOA. Individual anthocyanidins are fingerprints of colour-fleshed potato cultivars.     

Role of general stress-response alternative sigma factors σ(S) (RpoS) and σ(B) (SigB) in bacterial heat resistance as a function of treatment medium pH

This investigation aimed to determine the role of general stress-response alternative sigma factors σ^S (RpoS) and σ^B (SigB) in heat resistance and the occurrence of sublethal injuries in cell envelopes of stationary-phase Escherichia coli BJ4 and Listeria monocytogenes EGD-e cells, respectively, as a function of treatment medium pH. Given that microbial death followed first-order inactivation kinetics (R² > 0.95) the traditional D_T and z values were used to describe the heat inactivation kinetics.Influence of rpoS deletion was constant at every treatment temperature and pH, making a ΔrpoS deletion mutant strain approximately 5.5 times more heat sensitive than its parental strain for every studied condition. Furthermore, the influence of the pH of the treatment medium on the reduction of the heat resistance of E. coli was also constant and independent of the treatment temperature (average z value = 4.9 °C) in both parental and mutant strains.L. monocytogenes EGD-e z values obtained at pH 7.0 and 5.5 were not significantly different (p > 0.05) in either parental or the ?sigB deletion mutant strains (average z value = 4.8 °C). Nevertheless, at pH 4.0 the z value was higher (z = 8.4 °C), indicating that heat resistance of both L. monocytogenes strains was less dependent on temperature at pH 4.0. At both pH 5.5 and 7.0 the influence of sigB deletion was constant and independent of the treatment temperature, decreasing L. monocytogenes heat resistance approximately 2.5 times. In contrast, the absence of sigB did not decrease the heat resistance of L. monocytogenes at pH 4.0.The role of RpoS in protecting cell envelopes was more important in E. coli (4 times) than SigB in L. monocytogenes (1.5 times). Moreover, the role of σ^S in increasing heat resistance seems more relevant in enhancing the intrinsic resilience of the cytoplasmic membrane, and to a lesser extent, outer membrane resilience.Knowledge of environmental conditions related to the activation of alternative sigma factors σ^S and σ^B and their effects on heat resistance would help us to avoid and/or identify situations that increase bacterial stress resistance. Therefore, more efficient food preservation processes might be designed.     

Size of native and heated casein micelles,content of protein and minerals in milk from Norwegian Red Cattle—effect of milk protein polymorphism and different feeding regimes

Milk samples of 59 cows of the Norwegian Red Cattle breed receiving three different supplementary concentrates, were analysed for genotypes of caseins and whey proteins, the content of different milk salts (Ca²⁺, Ca, Mg and citrate), the content of total protein, casein and whey protein and the mean micellar size of native and heated casein micelles. The genotype of α_s1-casein had a statistically significant effect on the content of protein and casein, and the content of whey protein and the casein number were significantly influenced by different feeding regimes, and the content of citrate. The mean size of native and heated casein micelles was significantly influenced by the feeding regimes, genotype of α_s1-casein (native mean size only) and κ-casein, pH and the content of casein, whey protein and casein number. The heat-induced changes in mean micellar size were significantly affected by the calcium ion activity which accounted for approximately 40% of the total variation.     

Effect of source of trace minerals in either forage- or by-product–based diets fed to dairy cows: 2. Apparent absorption and retention of minerals

Eighteen multiparous cows were used in a split-plot replicated Latin square with two 28-d periods to evaluate the effects of source of supplemental Cu, Zn, and Mn (sulfates or hydroxy) on apparent absorption of minerals when fed in either a forage- or by-product–based diet. The by-product diets were formulated to have greater concentrations of NDF and lesser concentrations of starch, and specific ingredients were chosen because they were good sources of soluble fiber and β-glucans, which bind trace minerals in nonruminants. We hypothesized that hydroxy trace minerals would interact less with digesta and have greater apparent absorption compared with sulfate minerals, and the difference in apparent absorption would be greater for the by-product diet compared with the forage-based diet. During the 56-d experiment, cows remained on the same fiber treatment but source of supplemental trace mineral was different for each 28-d period; thus, all cows were exposed to both mineral treatments. During each period cows were fed no supplemental Cu, Zn, or Mn for 16 d, followed by 12 d of feeding supplemental minerals from either sulfate or hydroxy sources. Supplemental minerals for each of the mineral sources fed provided approximately 10, 35, and 32 mg/kg of supplemental Cu, Zn, and Mn, respectively, for both fiber treatments. Total Cu, Zn, and Mn dietary concentrations, respectively, were approximately 19, 65, and 70 mg/kg for the forage diets and 21, 85, and 79 for the by-product diets. Treatment had no effect on dry matter intake (24.2 kg/d) or milk production (34.9 kg/d). Cows consuming the by-product diets had greater Zn (1,863 vs. 1,453 mg/d) and Mn (1,790 vs. 1,588 mg/d) intake compared with cows fed forage diets, but apparent Zn absorption was similar between treatments. Manganese apparent absorption was greater for the by-product diets compared with the forage diets (16 vs. 11%). A fiber by mineral interaction was observed for Cu apparent absorption, as cows fed hydroxy minerals with forage diets had greater apparent absorption compared with cows fed sulfate minerals; however, the opposite was observed with the by-product diets. Source of supplemental trace minerals and type of fiber in diets affected availability of Cu and Mn and should be considered in ration formulation.     

Effects of Rested Harvesting on Muscle Metabolite Concentrations and K-Values in Chinook Salmon (Oncorhynchus tshawytscha) Fillets during Storage at 15 °C

Abstract: Improvement of harvesting procedures in aquaculture may also improve the quality and storage properties of the fish. The use of an anesthetic allows fish to be harvested with reduced stress and exhaustion, which affect fillet properties. We report here on the effects of rested harvesting on the postharvest metabolic profiles and K-values in Chinook salmon (Oncorhynchus tshawytscha) fillets stored near to the fish's acclimation temperature at 15 °C for 36 h. Fresh rested fillets were obtained by anesthesia with AQUI-S™. They had high cut surface pHs (7.63) and high concentrations of adenosine triphosphate (ATP) and creatine phosphate (3.75 and 8.73 μmol g⁻¹ respectively), which depleted over 12 h. In contrast, fresh exhausted fillets had low cut surface pHs (6.66) and ATP and creatine phosphate were depleted. Adenosine diphosphate (ADP) and β-nicotinamide adenine dinucleotide (NAD⁺) concentrations also remained significantly higher during the first 12 h of storage in rested fillets. In fresh rested fillets inosine monophosphate (IMP) concentrations reached maximum after 12 h storage (4.78 μmol g⁻¹), whereas maximum IMP concentrations occurred immediately postharvest in the exhausted fillets (6.42 μmol g⁻¹). After 36 h storage, K-values in exhausted fillets reached 52.11% compared to 19.27% in rested fillets. Rested harvesting of Chinook salmon improved the fillets’ metabolic potential postharvest, extending metabolite depletion times, changing IMP concentrations and reducing K-values. Practical Application: This study shows that an improved metabolic potential is maintained in salmon fillets from fish harvested in a rested state (that is, with no stress and exhaustion) using an isoeugenol based anesthetic (AQUI-S™). Improved understanding of postharvest metabolic function may help to improve quality and storage properties of high value fish tissues.     

Survival of human norovirus surrogates in milk, orange, and pomegranate juice, and juice blends at refrigeration (4 °C)

Fresh fruits, juices, and beverages have been implicated in human noroviral and hepatitis A virus outbreaks. The purpose of this study was to determine the survival of human norovirus surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in juices (orange and pomegranate juices), juice blends (pomegranate and orange juice) and milk over 0, 1, 2, 7, 14, and 21 days at refrigeration (4 °C). Juices, juice blends, and milk were inoculated with each virus over 21 days, serially diluted in cell culture media, and plaque assayed. MNV-1 showed no reduction in titer after 21 days in orange juice and milk, but moderate reduction (1.4 log) in pomegranate juice from a titer of 5 log(10) PFU/ml. However, MNV-1 was completely reduced after 7 days in the orange and pomegranate juice blend. FCV-F9 from a titer of 6 log(10) PFU/ml was completely reduced after 14 days in orange as well as pomegranate juice and by ～ 3 logs after 21 days in milk at 4 °C. Interestingly, FCV-F9 was completely reduced after 1 day in the orange and pomegranate juice blend at 4 °C. MS2 was reduced by ～ 1.28 log after 21 days in orange juice from a titer of 6 log(10) PFU/ml, and <1 log after 21 days in milk or pomegranate juice, with juice blends showing minimal reduction (<1 log) after 21 days at 4 °C. These results show the survival pattern of noroviruses that aid in the transmission of foodborne viral outbreaks. The data obtained can be used in quantitative viral risk assessment studies and to develop improved measures to prevent virus survival towards controlling outbreaks.     

A Comparison of War Iconography in the Archaeological Textiles of Paracas-Topará (in Southern Peru) and in the Weavings of Ayllu Qaqachaka (Bolivia) Today

Abstract

Drawing on some observations by Anne Paul concerning the iconography of textile borders in cloth from archaeological sites in Paracas-Topará (southern Peru), and her suggestion that these acted as “markers of the sacred,” we examine some ethnographic contexts in highland Bolivia that also concern borders: the final moment of the wayñu dance each year, and the finishing of textile and field borders. In each case, we propose that the object is to control certain spirits believed to dwell within these borders, so that they finish their creative task there. Finally, we examine the relation between the so-called “war of the ayllus” in Bolivia (in 2000), which produced dramatic changes in regional aesthetics, and textile structures postwar, in which images from textile borders came to occupy the central space of woven cloth. We explain these changes through a theory concerning the war dynamics that occur between the borders and centers of modern territories in conflict, and the way that local populations understand these, which might also have archaeological significance in the case of Paracas-Topará.     

Prevalence and relationships of sensory taint, 5α-androstenone and skatole in fat and lean tissue from the loin (Longissimus dorsi) of barrows, gilts, sows, and boars from selected abattoirs in the United States

This study assessed prevalence of boar taint in backfat and lean of barrows, gilts, sows, and boars, collected from abattoirs, without knowledge of the farms of origin, in different regions in the United States. Concentrations of 5α-androstenone (liquid chromatography/mass spectroscopy) and skatole (liquid chromatography with fluorescent detection) in backfat were measured. A trained panel evaluated boar taint aroma in heated samples. Mean 5α-androstenone and skatole levels were low among barrows, gilts, and sows, whereas 55.8% of boars scored above a 1.0 μg/g threshold for 5α-androstenone concentrations and 34.2% were above a 0.2 μg/g threshold for skatole concentrations. Mean aroma scores for backfat and lean from barrows, gilts, and sows were low. In comparison, 59.2% of boars had elevated mean aroma scores from fat samples and 31.7% from lean. Importantly, boar taint aroma was detectable by the trained panel in at least some animals in each of the sex classes.     

Potato bacterial wilt in Rwanda: occurrence,risk factors,farmers’ knowledge and attitudes

Potato is an important food commodity and efforts to increase its productivity should focus on addressing production limiting factors. Potato bacterial wilt (PBW) caused by Ralstonia solanacearum is one of the major constraints to potato production in Rwanda and no single method effectively controls the disease. Development of a sustainable management approach requires understanding of PBW distribution, risk factors, farmers’ knowledge and management attitudes. Therefore, we surveyed PBW disease and interviewed farmers in eight districts of Rwanda during March–April 2015. We detected PBW in all the surveyed districts and it was ranked as the major potato disease constraint. Among districts, disease incidence and severity varied from 5 to 24% and 3 to 13%, respectively, and was significantly higher in minor compared to major potato growing districts. Low PBW incidence and severity were associated with high altitude and low planting density, intercropping, crop rotation and avoidance of sharing farm tools. In all districts, farmers had little knowledge about PBW detection and spread, and the farmers’ awareness of PBW management was often inconsistent with their practices. This incomplete knowledge about PBW was likely caused by inadequate extension services since most information about PBW was acquired from fellow farmers, parents or other relatives. Thus raising awareness of PBW and integrated disease management, including practices that are associated with low PBW, could limit the impact of this disease and help to secure food and income for potato growing farmers in Rwanda.     

Mycoplasma bovis infection in dairy herds—Risk factors and effect of control measures

As Mycoplasma bovis spreads to new countries and becomes increasingly recognized as a disease with major welfare and economic effects, control measures on dairy farms are needed. To minimize the risk of infection spread to naive herds, all possible risk factors for M. bovis infection should be identified and controlled. Mycoplasma bovis was first diagnosed in dairy cattle in Finland in 2012, and by January 2020, 86 Finnish dairy farms (<1.5%) supporting M. bovis infections were identified. We evaluated risk factors for M. bovis infection using a questionnaire provided to 40 infected and 30 control dairy farms. Control measures were advised for 19 of the infected dairy farms during visits by a veterinarian. The course of the infection on those farms was followed by analyzing calf nasal swabs with PCR for presence of M. bovis 4 times at 6-mo intervals. Control measures included culling of M. bovis mastitic cows, isolation of new calves from older animals after initial M. bovis mastitic cows had been culled, prevention of nose-to-nose contact with infected animals, early detection of mastitis cases using M. bovis PCR, and hygiene measures mainly related to milking, calf pens, feeding buckets, and teats. Farms implemented the control measures related to the isolation of calves or avoidance of nose-to-nose contact in various ways, according to farm structures and financial circumstances. In our study, the control measures recommended to the dairy farms appeared effective, such that 13 of 19 farms reached a low risk level during at least 3 consecutive negative samplings from calves, with no M. bovis mastitis detected subsequently. Among risk factors, insemination with an M. bovis-positive bull indicated a trend of increasing the odds of M. bovis infection on the farm in a multivariable logistic model. In contrast, higher herd average milk yield had an association with lower odds for M. bovis infection. Occurrence of other infectious diseases affecting several animals on the dairy farm in the previous 6 mo before M. bovis infection were more frequent on M. bovis-infected farms.     

Importance of β,β-carotene 15,15'-monooxygenase 1 (BCMO1) and β,β-carotene 9',10'-dioxygenase 2 (BCDO2) in nutrition and health

In humans, varying amounts of absorbed β-carotene are oxidatively cleaved by the enzyme β,β-carotene 15,15'-monooxygenase 1 (BCMO1) into two molecules of all-trans-retinal. The other carotenoid cleavage enzyme β,β-carotene 9',10'-dioxygenase (BCDO2) cleaves β-carotene at the 9',10' double bond forming β-apo-10'-carotenal and β-ionone. Although the contribution of BCDO2 to vitamin A formation has long been debated, BCMO1 is currently considered the key enzyme for retinoid metabolism. Furthermore, BCMO1 has limited enzyme activity towards carotenoids other than provitamin A carotenoids, whereas BCDO2 exhibits a broader specificity. Both enzymes are located at different sites within the cell, with BCMO1 being a cytosolic protein and BCDO2 being located in the mitochondria. Expression of BCMO1 in tissues other than the intestine has recently revealed its function for tissue-specific retinoid metabolism with importance in embryogenesis and lipid metabolism. On the other hand, biological activity of BCDO2 metabolites has been shown to be important in protecting against carotenoid-induced mitochondrial dysfunction. Single-nucleotide polymorphisms (SNPs) such as R267S and A379V in BCMO1 can partly explain inter-individual variations observed in carotenoid metabolism. Advancing knowledge about the physiological role of these two enzymes will contribute to understanding the importance of carotenoids in health and disease.     

Can Acid Volatile Sulfides (AVS) Influence Metal Concentrations in the Macrophyte Myriophyllum aquaticum?

The difference between the molar concentrations of simultaneously extracted metals (SEM) and acid volatile sulfides (AVS) is widely used to predict metal availability toward invertebrates in hypoxic sediments. However, this model is poorly investigated for macrophytes. The present study evaluates metal accumulation in roots and stems of the macrophyte Myriophyllum aquaticum during a 54 day lab experiment. The macrophytes, rooting in metal contaminated, hypoxic, and sulfide rich field sediments were exposed to surface water with 40% or 90% oxygen. High oxygen concentrations in the 90% treatment resulted in dissolution of the metal-sulfide complexes and a gradual increase in labile metal concentrations during the experiment. However, the general trend of increasing availability in the sediment with time was not translated in rising M. aquaticum metal concentrations. Processes at the root-sediment interface, e.g., radial oxygen loss (ROL) or the release of organic compounds by plant roots and their effect on metal availability in the rhizosphere may be of larger importance for metal accumulation than the bulk metal mobility predicted by the SEM-AVS model.