Fraction S1 Research Articles

THE IMPACT OF EDARAVONE ON THE MARKERS OF CARBONYL-OXIDATIVE STRESS IN RATS WITH TRAUMATIC BRAIN INJURY

In the condition of traumatic brain injury (TBI), the brain develops a series of complex metabolic changes, including protein carbonylation, enhanced lipid peroxidation, impaired neurotransmitter release, and imbalanced energy supply, that are associated with the development of different functional disorders so the search for preventive medications in this pathology is very important. Edaravone is considered a supplementary drug in the treatment of different functional disorders of the central nervous system, but the mechanisms of its protective action remain under question. Aim. This comparative research aimed to study the effects of edaravone on the biomarkers of carbonyl-oxidative stress (COS) in rats with traumatic brain injury. TBI was caused by mechanical damage with a metal weight (450 g) falling from a height of 170 cm. Methods. Advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances, protein carbonyls (PC370/PC430) were studied using spectrophotometry in serum and fraction S1 in brain cortex and hippocampus of experimental animals. Edaravone supplementation may provide significant protection against brain hemorrhagic complications by reducing COS and oxidative modification of proteins. Resylts. In our study, edaravone demonstrated moderate efficacy in reducing serum PC430 and AOPP levels, indicating its ability to attenuate TBI-induced oxidative damage. In addition to its systemic effects, edaravone exerted targeted effects on COS-modified proteins in the hippocampus, even though such biomarkers were not altered significantly by TBI alone. Concluson. Further research is necessary to elucidate the primary mechanisms of action of this drug based on the data obtained.

Discovery and Characterization of a Dual-Function Peptide Derived from Bitter Gourd Seed Protein Using Two Orthogonal Bioassay-Guided Fractionations Coupled with In Silico Analysis.

The hydrolysate of bitter gourd seed protein, digested by the combined gastrointestinal proteases (BGSP-GPs), exhibited the most potent inhibition on angiotensin-I-converting enzyme (ACE) with an IC50 value of 48.1 ± 2.0 µg/mL. Using two independent bioassay-guided fractionations, fraction F5 from reversed-phase chromatography and fraction S1 from strong cation exchange chromatography exhibited the highest ACE inhibitory (ACEI) activity. Three identical peptides were simultaneously detected from both fractions and, based on the in silico appraisal, APLVSW (AW6) was predicted as a promising ACEI peptide. Their dipeptidyl peptidase-IV (DPP4) inhibitory (DPP4I) activity was also explored. The IC50 values of AW6 against ACE and DPP4 were calculated to be 9.6 ± 0.3 and 145.4 ± 4.4 µM, respectively. The inhibitory kinetics and intermolecular interaction studies suggested that AW6 is an ACE competitive inhibitor and a DPP4 non-competitive inhibitor. The quantities of AW6 in BGSP-GP hydrolysate, fractions F5 and S1, were also analyzed using liquid chromatography-tandem mass spectrometry. Notably, AW6 could resist hydrolysis in the human gastrointestinal tract according to the result of the simulated gastrointestinal digestion. To the best of our knowledge, this is the first discovery and characterization of a dual-function (ACEI and DPP4I activities) peptide derived from bitter gourd seed protein.

ISOLASI DAN KARAKTERISASI SENYAWA FENOLIK DARI DAUN PUTAT (Planchonia valida Blume) (ISOLATION AND CHARACTERIZATION OF PHENOLIC COMPOUND FROM PUTAT LEAVES (Planchonia valida Blume))

Gallic acid have been isolated from the leaves of the Putat plant (Planchonia valida Blume). This study aimed to isolate and characterize isolates from Putat leaves by phytochemical and FTIR spectrophotometry. The research procedures included extraction by maceration, partitioning by fractionation, vacuum liquid chromatography (KCV), gravity column chromatography (KKG), thin layer chromatography (TLC), and FTIR analysis. A total of 1400 grams of putat leaf powder was macerated to produce 159.243 grams (11.38%) of methanol extract. A total of 101 grams of methanol extract was dechlorophyllated to obtain 21.430 grams (21.21%) of dechlorophyllated extract. The dechlorophyllated extract was partitioned gradually with n-hexane and ethyl acetate to produce n-hexane fractions of 0.341 grams (1.591%), and ethyl acetate of 10.143 grams (47.33%), and methanol of 9.170 grams (42.79%). A phytochemical test showed that in the dechlorophyllated extract, the methanol and ethyl acetate fractions contained alkaloids, phenolics, flavonoids, and terpenoids while the n-hexane fraction contained alkaloids and flavonoids. A total of 7 grams of ethyl acetate fraction was fractionated by vacuum liquid chromatography to produce fractions B1 to B8. The B4 fraction was continued to the separation step by gravity column chromatography so that the fractions S1 to S9 were obtained. The S4 fraction was continued to the separation stage using preparative thin layer chromatography (TLC) to produce isolates S4.1 to S4.5. Isolate S4.1 was tested for purity by two-dimensional TLC showed that the isolate was not pure. The results of the phytochemical test with 5% FeCl3 spray reagent indicated a positive phenolic compound which was strengthened by FTIR characterization of the presence of –OH, -CH aromatic, -CH aliphatic, C=C, C=O and C-O goups. Based on these results, it was concluded that the isolate from the dechlorophyllated extract of Putat leaves belonged to phenolic compounds.

Nanoparticle Size-Dependent Antibacterial Activities in Natural Minerals

The size-dependent antibacterial activities of three minerals namely; alkali feldspar, calcite and stibnite are reported as examined individually against Escherichia coli and Staphylococcus aureus by evaluating minimum inhibitory concentration (MIC) with colony counting method, along with cell survivability assay (MTT). Each of these minerals were grinded into fine-size fractions-S1 (bulk), S₂ (ball milled) and S3 (nanosized) and spectroscopically characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-Vis) spectroscopy. Antibacterial activity was found to be highest in the nanosized (S3) minerals. Interaction between bacteria and nanosized mineral samples produce intracellular reactive oxygen species (ROS), which might cause higher bacterial mortality. The penetration due to nano-dimension is another significant observation as evidenced by bacterial FESEM micrographs. The current findings thus provide a pathway for future research on antibacterial products retrievable from widely available geological materials. The size dependant antibacterial activity of naturally formed minerals is a new insight to reduce bacterial contamination in living systems.

Production of Bioactive Compounds from the Sulfated Polysaccharides Extracts of Ulva lactuca: Post-Extraction Enzymatic Hydrolysis Followed by Ion-Exchange Chromatographic Fractionation.

This paper describes a novel combined post-extraction process for obtaining bioactive compounds from the aqueous high molecular weight sulfated polysaccharides (SPs) extracts of the green algae, Ulva lactuca. After extracting the SPs, they were enzymatically hydrolyzed then the hydrolysate (V45) was fractionated into eight different molecular weight fractions (F1–F8) using ion exchange chromatography. Crude SPs together with V45 and (F1–F8) were examined for their carbohydrate, protein, and sulfate contents. In addition, their degree of polymerization (DP) was estimated and they were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Fractions S1, F4, F5, and F8 showed promising antioxidant and antitumor activities in vitro. In particular, the remarkable antitumor activity of F5 on three types of cancer cell lines could be attributed to its comparable contents of protein, carbohydrate, and sulfate, in addition to its comparable contents of rhamnose and glucuronic acid, and the same for glucose and arabinose. F5 also possessed the highest Hill coefficient among the four promising fractions indicating a higher degree of cooperativity in ligand binding. Other influencing factors including DP, composition, and type of characteristic functional groups were also discussed. The implications of this work could potentially benefit the industries of food supplements and pharmaceuticals.

Induction of G2/M cell cycle arrest and phosphorylated-extracellular signal-regulated protein kinase 1 and 2-induced caspase 3/7-independent apoptosis in HT-29 cells by the combination of fraction S1 and citrinin from Penicillium strain H9318

OBJECTIVES: To determine the effect of potential anticancer property of secondary metabolites of Penicillium strain H9318. MATERIALS AND METHODS: Cytotoxicity of HT-29 cells was accessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay to give a preliminary comparison of the efficacy of fraction S1 and citrinin H9318. Mode of action of the combination treatment of fraction S1 and citrinin H9318 was determined by the cell cycle assay using propidium iodide-staining method performed with a flow cytometer. Further clarification of the anticancer mechanism of the combination treatment was carried out by the assays of pan-caspase, caspase-3/7, and western blot to examine the apoptosis of HT-29 cells. RESULTS: HT-29 cells show dose-dependent manner in cytotoxicity. HT-29 cells were arrested at G2/M phase with decrease in phosphorylated-retinoblastoma protein. Citrinin H9318, citrinin H9318 and fraction S1 combination-treated HT-29 cells show induction of pan-caspase. Caspase-3/7 was found decrease in the combination of citrinin H9318 and fraction S1 through up-regulation of phosphorylated-extracellular signal-regulated protein kinase 1 and 2 (p-ERK1/2). CONCLUSION: Citrinin H9318 alone did not reduce activity of caspase-3/7 significantly in the apoptosis of HT-29 cells. The combination treatment of fraction S1 and citrinin H9318 contributed to apoptosis via up-regulation of p-ERK1/2 with reduced activity of caspase-3/7.

A mass spectrometry and 1H NMR study of hypoglycemic and antioxidant principles from a Castanea sativa tannin employed in oenology

The ethanol extract of the commercial tannin Tan’Activ C, (from Castanea sativa wood), employed in oenology, was subjected to chromatography on XAD-16 affording fractions X1–X5, evaluated for total phenols content (GAE), antioxidant activity (DPPH, ORAC), and hypoglycemic activity (α-glucosidase inhibition). Fraction X3 showed GAE, radical scavenging activity, and α-glucosidase inhibition higher than those of the Castanea sativa extract, and was subjected to chromatography on Sephadex LH-20 to obtain fractions S1–S7, analyzed by HPLC/ESI-MS/MS and 1H NMR to identify the main active constituents. In fractions with higher antioxidant activity, gallic acid (4), grandinin (5), valoneic acid dilactone (9), 1,2,3-tri-O-galloyl-β-glucose (14), 3,4,6-tri-O-galloyl-β-glucose (15) and galloyl derivative of valoneic acid dilactone (21) were identified as the major constituents. The highest hypoglycemic activity was found in fractions S6 and especially S7; the major constituents of these fractions are valoneic acid dilactone (9), three tetragalloyl glucose isomers (16–18) and 1,2,3,4,6-penta-O-galloyl-β-glucose (23), previously reported as α-glucosidase inhibitors.

Effect of cadmium bioavailability in food on its compartmentalisation in carabids

Metals assimilated by organisms are sequestered in various compartments and some forms are more stable than others. Sequestration mechanisms used by invertebrates to detoxify metals and prevent interaction with important biomolecules include metal binding to proteins and other ligands, and storage in inorganic granules. The rate and extent at which metal concentrations in different compartments respond to metal concentrations in food and food characteristics has not received much attention, despite being of great relevance. We performed an experiment on the carabid beetle Pterostichus oblongopunctatus exposed to Cd via food made of ground mealworm (Tenebrio molitor) larvae, either reared on Cd contaminated medium or artificially spiked after grinding with CdCl2 solution. Thus, in both cases we used the same type of food, differing only in the soluble Cd pool available to the predators, represented by P. oblongopunctatus. Subcellular compartmentalisation of Cd into organelles, heat-sensitive and heat-stable proteins (the first supernatant, S1 fraction), cellular debris (the second supernatant, S2 fraction) and metal-rich granules (G fraction) was checked a few times during the contamination (90 d) and decontamination (24 d) phases in a toxicokinetic experiment by using different centrifugation steps. The results showed no effect of the type of food (naturally, Cd-N, vs. artificially contaminated with Cd, Cd-A) on Cd sequestration kinetics in P. oblongopunctatus, but the amount of Cd sequestered in the S1 and G fractions were in general higher in the Cd-A than the Cd-N treatment, indicating that Cd transfer in the food web depends on the speciation of the metal in the food. The proportional distribution of Cd over different fractions was, however, similar in beetles fed both food types. Most of the accumulated Cd in the beetles existed as fraction S1 (ca. 35%), which is important for the transfer of metals to higher trophic levels in a food web.

<i>Weissella cibaria</i> Fungistatic Activity against <i>Fusarium spp</i>. affecting Yellow Pitahaya

Fungistatic activity of a Lactic-Acid Bacteria (LAB) was assessed in vitro while isolated from its rumen fluid, against Fusarium oxysporum and Fusarium fujikoroi, basal-rot related species in yellow pitahaya. Fed batch was used to reproduce said LAB. Fungistatic activity kinetic tests were performed on the ferment (S1) and on two of the fractions obtained through centrifugation, supernatant (S2) and biomass (S3). The fungistatic activity was measured in two substrates, agar Man Rogosa Sharpe (MRS) and Potato Dextrose Agar (PDA). On S1 it was also performed lactic acid and acetic acid production kinetic tests as well as substrate consumption and biomass formation. Structural changes were evaluated on the fungi through microscopic electronics. The LAB was molecularly identified as Weissella cibaria. It was found that after eight hours of fermentation, fractions S1 and S3 performed the highest fungistatic activity against F. oxysporum and F. fujikoroi. Porosities were observed in the cell walls of the fungi as an effect of the LAB's fungistatic activity. These results indicate that LABs, when isolated from the animal habitat, may have a biotechnological potential to be used in the development of biocides, useful to control Fusarium in crops; for instance, to control yellow pitahaya basal rot.

Isolation of a potential anticancer agent with protein phosphatase inhibitory activity from soil-derived <i>Penicillium</i> sp strain H9318

Purpose: To determine the effect of the secondary metabolites from Penicillium sp. H9318 on cytotoxicity and cell cycle progression.Methods: A yeast PP1 inhibitory screening system was carried out to confirm the presence of anti-PP1c activity in crude acetone extracts of strain H9318. The extracts were fractionated and identified as Fraction S1 and Citrinin 9318 (CTN9318). Various cancer cell lines were used to test for the toxicity of the crude acetone extracts, Fraction S1 and Citrinin 9318, using MTT viability assay.Results: It was found that a colorectal cancer cell line, HT-29, was susceptible to Fraction S1 and Citrinin 9318. A propidium iodide (PI)-incorporated DNA assay was used to show that there was G2/M arrest in HT-29 by Citrinin 9318.Conclusion: Citrinin 9318 inhibits the viability of HT-29 via mitotic block. The results suggest that Citrinin 9318 is capable of exerting cytotoxicity and mitotic arrest in a colon cancer cell line, HT29.Keywords: Citrinin, Fraction S1, G2/M, HT-29, H9318, Protein phosphatase 1

Partial characterization and immunostimulatory activity of exopolysaccharides from Lactobacillus rhamnosus KF5

Lactobacillus rhamnosus KF5, a strain newly isolated from the faeces of a healthy human volunteer, has been shown to produce the exopolysaccharides (EPS) in skim milk. Two EPS fractions were separated from the fermented skim milk by removing proteins, ethanol precipitation, anion-exchange and gel permeation chromatography. Fraction S1, with a low average molecular weight of 1.36×104Da, was composed of glucose, arabinose, glucosamine, galactosamine and galactose in an approximate molar ratio of 2.03:1.29:1.25:0.72:0.61. Such monosaccharide composition of the exopolysaccharide by lactic acid bacteria has not been reported so far, and S1 is likely to be an unusual type of microbial EPS. Whilst Fraction S2, with a high average molecular weight of 1.23×106Da, contained rhamnose, glucose and galactose in a molar ratio of approximately 1.73:1.47:1.00. Both of EPS fractions could significantly stimulate splenocyte proliferation in vitro, indicating two EPS fractions had the potential immunomodulatory activity.

In vitro antioxidant activities of total flavonoids extracts from leaves and stems of Adenia lobata (Jacq.) Engl. (Passifloraceae)

Oxidant stress is implied in numerous illnesses as a triggering factor or partner to their complications. The present work aimed to determine the antioxidant activity of total flavonoids extracts from A. lobata and to identify the molecules that are supposed to be responsible for this activity. The crude extracts, obtained by maceration in 70% (v/v) aqueous methanol, have been extracted successively by hexane, chloroform, ethyl acetate and n-butanol. The crude (S1, S2), ethyl acetate (S1III, S2III) and n-butanol (S1IV, S2IV) extracts underwent a phytochemical screening in order to test the radical scavenging activity against 1, 1’ - diphenyl-2-picrylhydrazyl (DPPH). Qualitative analysis by thin layer chromatography permitted the study to put in evidence the flavonoids content of the different extracts. Contents in phenolic compounds were relatively high in the stems (3604 ± 511, 11 µg GAE/g) in relation to the leaves of A. lobata (3240 ± 711, 05 µg GAE/g). EC50 of 6, 422.5, 430 and 357.5 μg/ml were graphically determined for vitamine C, S1III, S2III, S1IV and S2IVrespectively; fractions S1, S2 and S2IV showed an EC50 greater than 500 μg/ml. Key words: Adenia lobata, flavonoids, antioxidant activity, DPPH, Ivorian pharmacopeia.

Nutrientes na serapilheira em um fragmento de Floresta Estacional Decidual, Itaara, RS

O presente estudo teve por objetivo quantificar a massa e o estoque de nutrientes da serapilheira sobre o solo em um fragmento de Floresta Estacional Decidual no município de Itaara, RS. Para a quantificação da serapilheira, a amostragem foi realizada conforme frações estabelecidas em metodologias: uma para folhas e galhos com diâmetro menor a 1 cm (S0) e outra para material lenhoso com diâmetro de 1 cm a 3 cm (S1), 3,1 cm a 6 cm (S2) e maior que 6 cm (S3). Para a avaliação da fração S0, foram coletadas aleatoriamente cinquenta amostras com moldura metálica de 25 cm x 25 cm, já para a avaliação das frações S1, S2 e S3, foram distribuídas aleatoriamente dez parcelas de 3 m x 2 m na área de estudo. O material amostrado foi acondicionado e levado ao Laboratório de Ecologia Florestal da Universidade Federal de Santa Maria onde foram secas, pesadas, moídas e analisadas quanto aos teores de macro e micronutrientes. Cerca de 45% da serapilheira depositada sobre o solo é formada por materiais lenhosos senescentes (galhos e troncos). As frações da serapilheira diferiram significativamente (p < 0,05), quanto aos teores de nutrientes, com exceção de Mg e Cu; geralmente a fração S0 apresentou teores mais altos de nutrientes. As frações S1, S2 e S3 apresentaram um acúmulo de nutrientes variando de 53,3% para o K a 8,7% para o Fe em relação ao total da serapilheira, demonstrando a importância da quantificação desses componentes durante a avaliação do estoque de nutrientes contidos na serapilheira de ecossistema florestal.

Fetuin-A (α2HS-Glycoprotein) Is a Major Serum Adhesive Protein That Mediates Growth Signaling in Breast Tumor Cells

Fetuin-A (α2HS-Glycoprotein) Is a Major Serum Adhesive Protein That Mediates Growth Signaling in Breast Tumor Cells

Episomal replication timing of γ-herpesviruses in latently infected cells

This study addresses the timing of gammaherpesviral episomal DNA replication with respect to the cell cycle. For the first time we analyzed a rhadinovirus, the prototype Herpesvirus saimiri (HVS), and compared it to the lymphocryptovirus Epstein-Barr virus (EBV). Newly synthesized DNA of latently infected B- or T-cells was first BrdU-labeled; then we sorted the cells corresponding to cell cycle phases G(0/1), G(2/M), and S (4 fractions S(1)-S(4)) and performed anti-BrdU chromatin immunoprecipitation. Next, DNA of different viral gene loci was quantitatively detected together with cellular control genes of known replication time. The sensitive technique is further enhanced by an internal coprecipitation standard for increased precision. Both gammaherpesviruses replicated very early in S-phase, together with cellular euchromatin. Our work suggests that early S-phase DNA replication is a general characteristic of episomal herpesviral genomes.

ANTIOXIDANT PROPERTIES OF COCOA POWDER

This study was aimed to determine antioxidant properties of cocoa powder. Crude cocoa extracts were fractionated using prepacked column (25 cm × 2.0 cm) with Sephadex LH 20 and an increase in water-acetone (85:15, 70:30, and 40:60, v/v) as elution. The resulting fractions 1 (F1), 2 (F2) and 3 (F3) were tested for phenolic contents, antioxidant capacity, identification of bioactive compounds liquid chromatography-mass spectrometry (LC-MS) and stability test. Theobromine and caffeine were major compounds detected in F1 and F2. Monomer, dimer and trimer were identified in F3 as m/z 289, 578 and 867, respectively. Addition of F1 and F2 could reduce antioxidant capacity of F3. Catechin and epicatechin in F3 was stable when stored at 4 and -20C for 5 months. High antioxidant capacity in F3 was likely due to the monomeric, dimeric and trimeric phenolic compounds. The presence of methylxanthines could reduce antioxidant capacity of flavonoids in cocoa powder.

Maturation Process of Photosynthetic Membranes Observed by Proton Magnetic Relaxation and Sorption Isotherm

Mild rehydration from the gaseous phase of the developing and mature lyophilized wheat photosynthetic membranes was investigated using hydration kinetics, adsorption isotherm and high power proton relaxometry. Hydration time courses are single exponential for all target air humidities; the hydration time t equals to (11.9± 3.6) h for the mature membranes, and (17.0± 3.2) h for the developing membranes. The sorption isotherm is sigmoidal in form and well fitted using the Dent model; the mass of water saturating primary binding sites equals ∆M/m0 = 0.033± 0.013 and 0.025± 0.007 for the mature and for the developing membranes, respectively, where m0 is the dry mass of the sample, and ∆M is mass of water taken up. Proton free induction decays distinguish: (i) an immobilized proton (Gaussian) component, S0, originating from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S1, from water bound to the primary water binding sites and localized in proximity of paramagnetic ions; (iii) an exponentially decaying contribution, L1, from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L2. A significant contribution of water “sealed” in the structure of lyophilized membrane (from the fraction S1 and L1) is detected. The mass of “sealed” water fraction is ∆MS/m0 = 0.047 ± 0.023 and 0.072 ± 0.021 for the mature and for the developing membranes, respectively.

Evaluation of Liquid Smoke Treated Ready‐to‐Eat (RTE) Meat Products for Control of Listeria innocua M1

Liquid smoke fractions (S1, S2, S3, and S4) were applied on ready-to-eat (RTE) meat products to control the growth of inoculated Listeria innocua M1. Turkey rolls and roast beef products were dipped in liquid smoke, surface inoculated with L. innocua M1 (10(2) CFU/25 cm(2) RTE meat surface), vacuum packaged, and stored at 4 degrees C. Section 8.5 of USDA's detection and isolation procedure for L. monocytogenes was employed in conjunction with a Micro-ID system for L. innocua M1 identification (ID). Products treated with smoke fractions S1, S2, and S3 were negative for L. innocua M1 at 2 and 4 wk during incubation at 4 degrees C. Products treated with S4 were positive for L. innocua M1 immediately following inoculation and after storage for 2 and 4 wk. Smoke fractions S1, S2, and S3 exhibited pH values lower than 4.6, acidity values higher than 1.5%, and carbonyl concentrations higher than 110 mg/mL. All liquid smoke fractions contained similar phenol concentrations (0.3 to 0.6 mg/mL), suggesting that phenols may have a limited role in the bactericidal effects of liquid smoke fractions against specific microorganisms.

Screening and characterization of microbial inhibitors against eukaryotic protein phosphatases (PP1 and PP2A)

To identify novel microbial inhibitors of protein phosphatase 1 (PP1). 750 actinomycetes and 408 microfungi were isolated from Sabah forest soils and screened for production of potential PP1 inhibitors using an in vivo screening system, in which candidate inhibitors were identified through mimicking the properties of PP1-deficient yeast cells. Acetone extracts of two fungi, H9318 (Penicillium) and H9978 (non-Penicillium) identified in this way showed inhibitory activity towards both mammalian PP1 and PP2A in an in vitro phosphatase assay, while extract from H7520 (Streptomyces) inhibited PP2A but not PP1. Consistently, using a drug-induced haploinsufficiency test, strains with either reduced PP1 or PP2A function were hypersensitive to H9318 and H9978 extracts whereas only the latter strain showed hypersensitivity to H7250 extract. H9318 extract was fractionated using RP-HPLC into two active peaks (S1 and S2). A yeast strain with reduced PP1 function showed hypersensitivity to fraction S2 whereas a strain with reduced PP2A function was hypersensitive to fraction S1. However, S1 and S2 inhibited both PP1 and PP2A activities to a similar extent. Three candidate PP inhibitors have been identified. Further development may generate useful research tools and ultimately therapeutic agents.

Combined effects of the fungicide propiconazole and agricultural runoff sediments on the aquatic bryophyte Vesicularia dubyana

Pesticides, firmly attached to the topsoil, might enter nearby watercourses at periods with high erosive loss of sediments. Therefore, exposure of aquatic organisms to these low mobility pesticides, in many cases, will coincide with a high sediment concentration. In this study, both individual and combined effects of propiconazole and runoff sediment on the aquatic model bryophyte Vesicularia dubyana are studied. Individual exposure to propiconazole induced responses in V. dubyana at rather low concentration levels (approximately 1 microg/L), showing that harmful effects of propiconazole potentially may occur in watercourses draining propiconazole-treated fields. Individual exposure to the sediment size fractions S1 (0.16-2 microm) and S2 (0.03-0.16 microm) caused plant stress at a concentration of 100 mg/L. The coarser fraction S1 showed strong inhibition effects on photosynthesis, probably due to light attenuation. Compared to S1, the suspension with the finer fraction S2 showed lower turbidity, higher nutrient content, and a higher proportion of sediment-bound propiconazole. The combined effects of propiconazole and suspended sediment are dependent on concentrations of sediment and propiconazole. At low sediment concentration (e.g., 100 mg/L), neither S1 nor S2 reduce the toxicity of propiconazole, as only 2% of propiconazole are bound to particles. An increase in sediment concentration decreases the bioavailable concentration of propiconazole; however, at the same time, this increases the turbidity, thereby inhibiting plant photosynthesis.