Plant iron acquisition strategy exploited by an insect herbivore.

Insect herbivores depend on their host plants to acquire macro- and micronutrients. Here we asked how a specialist herbivore and damaging maize pest, the western corn rootworm, finds and accesses plant-derived micronutrients. We show that the root-feeding larvae use complexes between iron and benzoxazinoid secondary metabolites to identify maize as a host, to forage within the maize root system, and to increase their growth. Maize plants use these same benzoxazinoids for protection against generalist herbivores and, as shown here, for iron uptake. We identify an iron transporter that allows the corn rootworm to benefit from complexes between iron and benzoxazinoids. Thus, foraging for an essential plant-derived complex between a micronutrient and a secondary metabolite shapes the interaction between maize and a specialist herbivore.

Convergent evolution of a metabolic switch between aphid and caterpillar resistance in cereals.

Tailoring defense responses to different attackers is important for plant performance. Plants can use secondary metabolites with dual functions in resistance and defense signaling to mount herbivore-specific responses. To date, the specificity and evolution of this mechanism are unclear. Here, we studied the functional architecture, specificity, and genetic basis of defense regulation by benzoxazinoids in cereals. We document that DIMBOA-Glc induces callose as an aphid resistance factor in wheat. O-methylation of DIMBOA-Glc to HDMBOA-Glc increases plant resistance to caterpillars but reduces callose inducibility and resistance to aphids. DIMBOA-Glc induces callose in wheat and maize, but not in Arabidopsis, while the glucosinolate 4MO-I3M does the opposite. We identify a wheat O-methyltransferase (TaBX10) that is induced by caterpillar feeding and converts DIMBOA-Glc to HDMBOA-Glc in vitro. While the core pathway of benzoxazinoid biosynthesis is conserved between wheat and maize, the wheat genome does not contain close homologs of the maize DIMBOA-Glc O-methyltransferase genes, and TaBx10 is only distantly related. Thus, the functional architecture of herbivore-specific defense regulation is similar in maize and wheat, but the regulating biosynthetic genes likely evolved separately. This study shows how two different cereal species independently achieved herbivore-specific defense activation by regulating secondary metabolite production.

Direct residue analysis of systemic insecticides and some of their relevant metabolites in wines by liquid chromatography - mass spectrometry.

A direct large volume injection (DI-LVI) high performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for the quantitative determination of 16 systemic insecticides and their main plant metabolites. The assays were conducted on commercial red and white wines made from grapes grown in major wine-producing regions nationally and internationally. Using a 1:20 dilution and an injection volume of 800µL, a limit of quantitation (LOQ) of 1µgL-1 for all analytes was achieved. Matrix-matched standards (MM) were used for accurate quantitation. Imidacloprid (IMI) and methoxyfenozide (MET) were the most frequently detected parent insecticides in the wines reaching concentrations of 1-132µgL-1. Two important plant metabolites imidacloprid-olefin (IMI-OLE) and spirotetramat-enol (SPT-EN) were found at higher concentrations. In five samples SPT-EN was detected in the mgL-1 range with a maximum concentration of 16.3mgL-1 measured in a conventional white wine sample. Most "organic" wines contained no detectable or low insecticide residues, except for one sample, which showed the highest IMI (14.7µgL-1) and IMI-OLE (331µgL-1) concentrations. Considering the maximum residue limit (MRL) definition for the different insecticides, three "conventional" wine samples were non-compliant for SPT. This study highlights the importance to determine both parent and metabolite forms of systemic insecticides in the finished product.

Quantitative determination of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides in sewage sludges using supercritical fluid extraction and mass spectrometric detection.

Supercritical CO2 extraction (SFE) proved to be a valuable, fast, quantitative and partly selective extraction technique for determining polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and chlorinated pesticides (OCPs) in sewage sludges of different catchment areas based on a comparison study with certified reference materials (CRMs) and on recovery data. Most PCB extracts could be measured directly after SFE whereas for PAHs a short clean-up improved the final separation by high-resolution capillary gas chromatography. Due to the amount of coextracted compounds and the low levels of OCPs, extracts obtained by SFE had to be submitted to a multistep clean-up for final measurement. Average concentrations of 6.9 mg/kg dry mass (dm) for the sum of the 16 Environmental Protection Agency PAHs, 0.1 mg/kg dm for the sum of the seven PCB congeners and 0.002-0.072 mg/kg dm for the OCPs were found in the sewage sludges. Compared to studies performed earlier in our laboratory PAHs are still present in similar concentrations whereas PCB levels have decreased significantly. OCPs could be detected in only low amounts. A correlation between sludge type and degree of contamination could only be found for PAHs.

Comparison of high resolution gas chromatography with electron impact and negative ion mass spectrometry detection for the determination of coplanar polychlorobiphenyl congeners in sewage sludges.

The three most toxic coplanar PCB 77, 126 and 169 have been identified and quantified at ultra trace levels (0.02-4.8 ng/gdw) in swiss sewage sludge samples applying high resolution capillary gas chromatography (HRGC) and electron impact (EI) as well as negative ion chemical ionization (NCI) mass spectrometry (MS). NCI mass spectra have been dominated by the molecular ion as base peak and virtually no fragmentation has been observed. Detection limits of the planar PCB under single ion monitoring (SIM) conditions have been typically 100 fg for NCI-MS and 1 pg for EI-MS. NCI-MS was the preferred detection method for the determination of very low concentrations of these important contaminants in sewage sludge samples.

Concentrations and distribution of some polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in an ombrotrophic peat bog profile of Switzerland.

An efficient method was developed for the analysis of selected PCBs and PAHs in dry peat samples. The method includes a shaking extraction using acetone and hexane followed by the purification of the crude extract by gel permeation chromatography (GPC) which turned out to be the key clean-up step. The method was used to determine seven indicator PCBs and 16 EPA-PAHs in individual sections of an ombrotrophic peat core in south-west Switzerland. The maximum concentrations of PCBs (19 microg sigma PCBs/kg dm) were found at a peat depth of 10-15 cm which is estimated to correspond to a time period of 1976-1960 whereas the PAH profile showed a maximum (2853 microg sigma PAHs/kg dm) at a depth of 20-25 cm which represents circa 1951-1930. Compared to these maxima, the concentrations of PAHs in the top layer (1990-1986) are six times lower, but the decline in PCBs is only 38%. The concentration profiles are generally consistent with known changes in contaminant emissions, and suggest that more detailed studies of ombrogenic peat bog profiles could be used for detailed reconstructions of the changing atmospheric fluxes of these and other organic contaminants.

Nitro musks, nitro musk amino metabolites and polycyclic musks in sewage sludges. Quantitative determination by HRGC-ion-trap-MS/MS and mass spectral characterization of the amino metabolites.

Nitro- and polycyclic musks were quantified in sewage sludge samples from different catchment areas using high-resolution gas chromatography (HRGC) and ion-trap MS/MS. Collision induced dissociation (CID) turned out to be a useful tool for quantification of the analytes. Negative chemical ionization (NCI) quadrupole MS in the selected ion mode (SIM) showed similar sensitivities compared to ion trap MS/MS. Among the nitro musks, musk ketone (MK) and musk xylene (MX) were the main compounds in predominantly domestic sewage sludges, found at low microgram/kg dry matter (d.m.) whereas polycyclic musks were present in domestic as well as in industrial sludges up to 12 mg/kg d.m. Galaxolide (HHCB) and Tonalide (AHTN) were the major polycyclic musks found in the sludges. Amino metabolites of the nitro musks, amino musk xylene (AMA), amino musk moskene (AMM) and amino musk ketone (AMK) were detected for the first time in sewage sludges, and reached partly higher concentrations compared to the parent compounds.

Quantitative determination of 1 -hydroxypyrene in bovine urine samples using high-performance liquid chromatography with fluorescence and mass spectrometric detection.

An analytical method was developed to determine quantitatively 1-hydroxypyrene (OHP) in bovine urine samples. The procedure includes an enzymatic hydrolysis to cleave the conjugated metabolite, an enrichment step using solid phase extraction with a non-polar rinse step and elution with dichloromethane. A final clean-up on silicagel was performed before high-performance liquid chromatography (HPLC) analysis and fluorescence detection. Alternatively, HPLC and electrospray ionization in the negative ion mode applying selective ion monitoring acquisition revealed to be a highly sensitive detection method allowing the quantitation of low pg of OHP in the urine samples. The method was successfully applied to the determination of OHP in bovine urine samples from animals living in urban and rural areas. Urine concentrations of OHP were significantly higher (median 8.6 microg l(-1)) of bovines living close to a highway.

Considerations about the enantioselective transformation of polycyclic musks in wastewater, treated wastewater and sewage sludge and analysis of their fate in a sequencing batch reactor plant.

The present work consists of two distinct parts: in the first part enantioselective GC was used to separate the different enantiomeric/diastereomeric polycyclic musks, PCMs (HHCB, AHTN, AHDI, ATII and DPMI) including the main transformation product of HHCB, HHCB-lactone, in wastewater and sewage sludge. After optimization all PCMs were resolved on a cyclodextrin containing Rt-BDEXcst capillary GC column. Enantiomeric ratios of PCMs in a technical mixture were determined and compared to those obtained from enantioselective separation of wastewater and sewage sludge samples. In general, enantiomeric ratios were similar for most materials in influent, effluent and stabilized sewage sludge. However, the ratios for HHCB, AHDI and particularly ATII suggest some stereospecific removal of these compounds. In the second part, a field study was conducted on a wastewater treatment plant comprising a sequencing batch reactor. Concentrations of HHCB, AHTN, ADBI, AHDI, ATII, DPMI and HHCB-lactone were determined by non-enantioselective GC in daily samples of influent, effluent and activated sludge during one week. Mean concentrations in influent were 6900 and 1520 ng/l for HHCB and AHTN, respectively. The other PCMs exhibited contents 200 ng/l. Mean percent removal was between 61% (AHDI) and 87% (HHCB) resulting in mean effluent concentrations below 860 ng/l. HHCB-lactone concentration increased during wastewater treatment with a mean in the influent of 430 ng/l and in the effluent of 900 ng/l, respectively, indicating a degradation of HHCB.

Concentrations and specific loads of polycyclic musks in sewage sludge originating from a monitoring network in Switzerland.

Polycyclic musks (HHCB, AHTN, ADBI, AHDI, ATII) and a metabolite of HHCB (HHCB-lactone) were analyzed in sewage sludge samples within the framework of a monitoring network in Switzerland. Mean values in stabilised sludge from 16 wastewater treatment plants were 20.3 mg/kg d.m. for HHCB, 7.3 mg/kg d.m. for AHTN and 1.8 mg/kg d.m. for HHCB-lactone, respectively. Contents of ADBI, AHDI and ATII were between 0.1 and 1.8 g/kg d.m. The results show that polycyclic musks origin mainly from private households and that loads from craft industry, industry and atmospheric deposition are negligible. The technology of wastewater treatment and sludge processing seems to be of minor importance for degradation processes of polycyclic musks. The calculated input in wastewater of polycyclic musks is lower by a factor of 5-7 than the estimates based on use volumes. This discrepancy might be explained by degradation processes, other emission pathways than wastewater or inappropriate estimation of production volumes.

Determination of phthalates in crude extracts of sewage sludges by high-resolution capillary gas chromatography with mass spectrometric detection.

A simple solvent extraction by ethyl acetate without subsequent cleanup was used to determine 16 phthalic acid esters (PAEs), including bis(2-ethylhexyl) phthalate (DEHP), in sewage sludge samples from different catchment areas. The compounds were separated on a gas chromatographic capillary column with a nonpolar HT-8 stationary phase. For most of the PAEs, internal standard quantification with deuterated dibutyl phthalate (DBP) and deuterated DEHP was best achieved by using electron ionization mass spectrometry in the selected-ion monitoring mode. Because of its high concentrations in the sludges, DEHP was quantified in the full-scan acquisition mode. Molecular weight and ester-type information for the PAEs was obtained in the positive chemical ionization mode with methane as the reagent gas. Finally, selected sewage sludges containing different amounts of industrial wastewater were analyzed by the proposed method. DEHP was the most abundant compound found at 21-114 mg/kg x dm, followed by the lower-molecular weight PAEs diethyl phthalate, diisobutyl phthalate, and DBP and the higher-molecular weight compounds butylbenzyl phthalate, dicyclohexyl phthalate, di-n-octyl phthalate, and dinonyl phthalate, which were present mostly at <1 mg/kg x dm.

Mass flow of polycyclic musks in two wastewater treatment plants.

Synthetic musks are found in varying amounts in many consumer products. After use, synthetic musks go down the drain into the sewer system and then reach wastewater treatment plants (WWTPs). In this study, mass flows of two synthetic polycyclic musks, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[gamma]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), along with HHCB-lactone (the oxidation product of HHCB) were examined in two WWTPs. Wastewater and sludge samples were collected at various stages of the treatment process for analysis. HHCB, AHTN, and HHCB-lactone were found in all wastewater samples at concentrations in the ranges of 1780 to 12700, 304 to 2590, and 146 to 4000 ng/L, respectively. The highest concentrations for all compounds were found in sludge samples. Sludge samples contained HHCB at 7.23 to 108 mg/kg dry weight, AHTN at 0.809 to 16.8 mg/kg dry weight, and HHCB-lactone at 3.16 to 22.0 mg/kg dry weight. This is the first study to report HHCB-lactone in wastewater and HHCB, HHCB-lactone, and AHTN in sludge in WWTPs from the United States. HHCB and AHTN concentrations decreased during treatment. However, the concentrations of HHCB-lactone increased in water after treatment. Based on the daily flow rates and mean concentrations of the three compounds in effluent, a WWTP representative of those studied here is expected to release 288 g HHCB, 60.4 g AHTN, and 158 g HHCB-lactone/100,000 people/d. Partitioning HHCB, AHTN, and HHCB-lactone to sludge is the major removal mechanism for polycyclic musks in WWTPs.

[10-Acyldithranol dimers; new derivatives of the antipsoriatic dithranol; synthesis, characterization and biochemical properties]. / 10-Acyldithranol-Dimere; Neue Derivate des Antipsoriatikums Dithranol; Syntheseversuche, Charakterisierung und biochemische Eigenschaften.

With regard to the synthesis of 10-(omega-carboxyacyl)-derivatives dithranol 1 was reacted with the carboxylic acid dichlorides of succinic acid, glutaric acid, adipic acid and pimelic acid in toluene and collidin as a base. Instead of the expected derivatives the 10-acyldithranol dimers 5-7 were isolated as main products except for the reaction of succinyl chloride where only lactone 2 was formed. Moreover the 6-ring lactone 3 as a side product and traces of the 7-ring lactone 4 could also be isolated and characterized. All compounds revealed to be inhibitors of the enzyme glucose-6-phosphate dehydrogenase, indicating antipsoriatic activity.

[Synthesis, characterization, racemation and biochemical studies on 10-acylderivatives of chrysarobin: sorbylchrysarobin, beta-carbethoxypropionylchrysarobin and senecioylchrysarobin]. / Syntheseversuche, Charakterisierung, Razemattrennung und biochemische Eigenschaften von 10-Acylderivaten des Chrysarobins: Sorbylchrysarobin, beta-Carbethoxypropionylchrysarobin und Senecioylchrysarobin.

The racemic synthesis of three 10-acylderivatives of chrysarobin (1) is described. Senecioylchrysarobin (3), beta-carbethoxypropionylchrysarobin (4) and sorbylchrysarobin (5) were prepared by reaction of (1) with the corresponding carboxylic acid chlorides and collidine as a base in toluene. The separation of the racemates of (3) and (5) on a chiral stationary phase is demonstrated for the first time. All of the new compounds showed an increased potency of inhibition of the enzyme glucose-6-phosphate dehydrogenase, an indication for possible antipsoriatic activity.

[Chemical instability of the antipsoriatic dithranol and chrysarobin in aqueous systems: oxidation behavior]. / Chemische Instabilität der Antipsoriatika Dithranol und Chrysarobin in wässerigen Systemen: Ein Beitrag zum Oxidationsverhalten.

Decomposition of dithranol (1) and chrysarobin (4) in homogeneous and heterogeneous buffer solutions (pH 7.5) were studied by means of HPLC-chromatography. Half lives of (1) under homogeneous conditions were 1 h 15 min., under heterogeneous conditions 2 h 45 min., whereas in the case of (4) 3 h and 30 min. respectively were measured. (1) was degraded to dihydroxyanthrachinon (2) and dimeric dithranol (3), the amount of (2) and (3) depending of the chosen conditions, whereas degradation of (4) under heterogeneous conditions revealed no oxidation products. On the other hand two metabolites of (4) were detected in homogeneous buffer solutions. The presenting studies clearly show the different ways of decomposition of (1) and (4) in homogeneous and heterogeneous solutions.

[Synthesis and biochemical properties of new 10-acyl derivatives of dithranols: acetylsalicyldithranol and 1-acetyllactyldithranol]. / Synthese und biochemische Eigenschaften von weiteren 10-Acylderivaten des Dithranols: Acetylsalicyldithranol und L-Acetyllaktyldithranol.

By reaction of the corresponding acid chlorides of acetylsalicylic acid (8) and L-acetyllactic acid (5) with dithranol (1) in toluene and collidin or pyridine as a base two new 10-acylderivatives of (1) were prepared: L-acetyllactyldithranol (2) and acetylsalicyldithranol (3). Both derivatives strongly inhibited the enzyme glucose-6-phosphate dehydrogenase, indicating possible antipsoriatic activity.

Synthesis and characterization of new 10-acylderivatives of the antipsoriatic agent dithranol: coupling products of dithranol with all-trans-retinoic acid, 13-cis-retinoid acid and an aromatic analogue of retinoic acid: all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl- nona-2,4,6,8-tetraenoate.

The synthesis of new 10-acylderivatives of dithranol 1 is described. Compound 1 was reacted with the acid chlorides of all-trans retinoic acid 5, 13-cis-retinoic acid 6 and all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-nona-2,4,6,8- tetraenoate 7 in toluene and collidin as a base to give the coupling products 2, 3 and 4. The different structures were confirmed by high resolution 1H- and 13C-NMR spectroscopy. Initial investigations with the enzyme glucose-6-phosphate dehydrogenase indicate that all of them are inhibitors of the protein and therefore might have antipsoriatic activity.

Analysis of nitro musk compounds and their amino metabolites in liquid sewage sludges using NMR and mass spectrometry.

A method using HRGC ion trap MS/MS for measuring simultaneously amino metabolites and the parent compounds, the nitro musks, an important group of organic fragrance components found in sewage sludges, was developed. The monoamino metabolites were synthesized and characterized by 1H/13C NMR and mass spectroscopy. Among the nitro musks, musk ketone was the major compound, found at an average concentration of 5 microg/kg of dry mass (dm) whereas musk xylene was detected in only one sample (30 microg/kg dm). Three amino metabolites were identified, namely, 1-tert-butyl-3,5-dimethyl-4-amino-2,6-dinitrobenzene, 1,1,3,3,5-pentamethyl-4-nitro-6-aminoindane, and 4-acetyl-1-tert-butyl-3,5-dimethyl-2-nitro-6-aminobenzene, the corresponding reduction products of the nitro musks xylene, moskene, and ketone. These metabolites were present in partly higher concentrations in the sludges than the corresponding nitro musk compounds. Musk xylene and musk moskene were mainly found as their monoamino metabolites, underlining the importance of anaerobic reduction processes in the sewage treatment plant.

Biotransformation of Dehydroabietic, Abietic, and Isopimaric Acids by Mortierella isabellina Immobilized in Polyurethane Foam.

Polyurethane foam supports immobilization of Mortierella isabellina ATCC 38063, a zygomycete that hydroxylates and thereby detoxifies resin acids found in certain pulp mill effluents. The fungus becomes entrapped as it threads growing mycelia through the open foam matrix. The tenacity of binding and the amount of biomass bound depend on initial spore numbers and nutrient concentration. Optimal dehydroabietic acid transformation occurs with early-stationary-phase foam-bound mycelia suspended in buffer at pH 6.5 to 8.5 with aeration >0.1 liter liter min and near a temperature maximum of 33 degrees C. Neither a greater number of similarly loaded foam cubes nor a greater surface area for similar amounts of biomass increased transformation rates. Compared to free mycelial cultures, foam presence retards growth and decreases the rate of precursor transformation but does not alter the nature of the metabolites formed from dehydroabietic acid, abietic acid, or isopimaric acid. Diffusional barriers or binding of substrates in an inaccessible manner may cause the observed inhibitions. Overall, foam immobilization stabilizes enzymic activity and is a facile laboratory process with scaleup potential.