Considerations on the use of the p-nitrophenyl phosphomonoesterase assay in the study of the phosphorus nutrition of soil borne fungi

The p-nitrophenyl phosphomonoesterase assay (p NPPase) is commonly used to measure cell-wall-associated and extracellular phosphatase activity of soil fungi. p NPPases are usually assayed in the context of fungal nutrition, where inorganic P supply might be enhanced by the mineralisation of monoester organic P sources in the soil. The importance of the assay to the P nutrition of soil fungi is considered based on the evidence currently available including the consistency of methodological approach. The nature of organic P in the soil and the relevance of the assay to some specific soil substrates is discussed, particularly the chemistry and bioavailability of myo-inositol hexakisphosphate and the lower inositol phosphates. The evidence for the long-term stability of p NPPases in the soil is examined in the light of the persistence of p NPPase in soils. The role of persistent extracellular fungal p NPPases in the soil P cycle is discussed. Conclusions from p NPPase based studies must be based upon an appreciation of the constraints of the assay and the complex chemistry of organic P and p NPPase in the soil.

Some potential inaccuracies of the p -nitrophenyl phosphomonoesterase assay in the study of the phosphorus nutrition of soil borne fungi

The p-nitrophenol phosphomonoesterase assay (pNPPase) is commonly used to measure cell-wall-associated and extracellular phosphatase activity of soil fungi. pNPPases are usually assayed in the context of fungal nutrition, where inorganic P supply might be enhanced by the mineralisation of organic P sources in the soil. We report here on a series of experiments with the ectomycorrhizal basidiomycete Hebeloma cylindrosporum that highlight components of accepted methodology that might impinge on the reliability of the assay. These include the loss of pNPPase after filtration, inaccuracies in measuring wall-associated enzyme and the ample pool of intracellular pNPPase can be mistakenly measured as external pNPPase if cells are accidentally damaged.

Capillary assay device with internal hydrophilic coating

The present invention provides assay devices having a unitary body with an exterior surface, the unitary body being substantially transparent to visible light and formed from a material having a refractive index in the range 1.26 to 1.40, the refractive index being measured at 20 °C with light of wavelength 589 nm, and wherein the unitary body is formed from a hydrophobic material, and at least two capillary bores extending internally along the unitary body, wherein at least a portion of the surface of each capillary bore includes a hydrophilic layer for retaining an assay reagent, and wherein the hydrophilic layer is also substantially transparent to visible light to allow optical interrogation of the capillary bores through the capillary wall. The present invention also provides assay systems including such assay devices, methods of performing an assay using such assay devices and method of method for manufacturing such assay devices.

Sediment-contact fish embryo toxicity assay with Danio rerio to assess particle-bound pollutants in the Tiete River Basin (Sao Paulo, Brazil)

The Tiete River and its tributary Pinheiros River receive a highly complex organic and inorganic pollutants load from sanitary sewage and industrial sources, as well as agricultural and agroindustrial activities. The aim of the present study was to evaluate the embryotoxic and teratogenic effects of sediments from selected locations in the Tiete River Basin by means of the sediment contact embryo toxicity assay with Danio rerio, in order to provide a comprehensive and realistic insight into the bioavailable hazard potential of these sediment samples. Lethal and sub-lethal effects were recorded, and high embryo toxicity could be found in the samples not only in the vicinity of the megacity Sao Paulo (Billings reservoir and Pinheiros River samples), but also downstream (in the reservoirs Barra Bonita, Promissao and Tres Irmaos). Results confirm that most toxicity is due to the discharges of the metropolitan area of Sao Paulo. However, they also indicate additional sources of pollutants along the river course, probably from industrial, agricultural and agroindustrial residues, which contribute to the degradation of each area. The sediment contact fish embryo test showed to be powerful tool to detect embryo toxicity in sediments, not only by being a sensitive method, but also for taking into account bioavailability. This test provides an ecological highly realistic and relevant exposure scenario, and should therefore be added in ecotoxicological sediment quality assessments. (C) 2011 Elsevier Inc. All rights reserved.

A PCR-RFLP assay for gender assignment in the three-toed sloths (Bradypus, Pilosa, Bradypodidae)

The three-toed sloths (Bradypus) are slow-moving arboreal neotropical mammals. Understanding demographic variables (such as sex ratio) of populations is a key for conservation purposes. Nevertheless, gender assignment of Bradypus is particularly challenging because of the lack of sexual dimorphism in infants and in adults, particularly B. torquatus, the most endangered of the three-toed sloths, in which sex is attributed by visual observation of the reproductively active males. Here, we standardized a method for sexing Bradypus individuals using PCR-RFLP of sex-linked genes ZFX/ZFY. This assay was validated with known-gender animals and proved accurate to assign gender on three Bradypus species.

Chronic action of association of zidovudine, lamivudine and ritonavir on pregnant rats. A biologic assay

Purpose: To evaluate at term the effects of a highly active antiretroviral (HAAR) drug association administered during the entire period of rat pregnancy. Methods: Three groups (n = 10 each) of adult pregnant rats were treated with an oral solution of HAAR (Exp 1 = 10/5/20 mg/kg b.w.; Exp 2 = 30/15/60 mg/kg b.w.; Exp 3 = 90/45/180 mg/kg b.w.) from day ""0"" up to the 20th day of pregnancy. A fourth group served as a control. At term (20th day) the rats were killed under deep anesthesia and the number of implantations, resorptions, living fetuses, placentae and intrauterine deaths were recorded. Results: The highest HAAR doses caused lower maternal weight gain, lower litter weights, and lower placental weights compared to the control group. Conclusions: HAAR during the entire period of rat pregnancy can reduce maternal body weight gain and lower term placental weight.

A quantitative TaqMan PCR assay for the detection of Mycoplasma suis

Aim: To develop a TaqMan probe-based, highly sensitive and specific quantitative PCR (qPCR) assay for the detection and quantification of Mycoplasma suis in the blood of pigs. Methods and Results: Primers and probes specific to Myc. suis 16S rRNA gene were designed. The qPCR assay`s specificity, detection limit, intra- and inter-assay variability were evaluated and its performance was compared with a Myc. suis conventional PCR assay (cPCR). Blood of two experimentally infected pigs, 40 Indiana pigs, 40 Brazilian sows and 28 peccaries were tested. The assay detected as few as ten copies of Myc. suis plasmids and was 100-fold more sensitive than the cPCR. No cross-reactivity with nontarget pig mycoplasmas was observed. An average of 1.62 x 10(11) and 2.75 x 10(8) target copies ml(-1) of blood were detected in the acutely and chronically infected pigs, respectively. Three (7.5%) pigs and 32 (80.0%) sows were positive while all peccaries were negative for Myc. suis. Conclusion: The developed qPCR assay is highly sensitive and specific for Myc. suis detection and quantification. Significance and Impact of the Study: TaqMan qPCR is an accurate and quick test for detection of Myc. suis infected pigs, which can be used on varied instrumentation platforms.

A real-time polymerase chain reaction assay for the identification and quantification of American Leishmania species on the basis of glucose-6-phosphate dehydrogenase

A real-time polymerase chain reaction (PCR) test was developed on the basis of the Leishmania glucose-6-phosphate dehydrogenase locus that enables identification and quantification of parasites. Using two independent pairs of primers in SYBR-Green assays, the test identified etiologic agents of cutaneous leishmaniasis belonging to both subgenera, Leishmania (Viannia) and Leishmania (Leishmania) in the Americas. Furthermore, use of TaqMan probes enables distinction between L. (V.) braziliensis or L. (V.) peruviania from the other L. (Viannia) species. All assays were negative with DNA of related trypanosomatids, humans, and mice. The parasite burden was estimated by normalizing the number of organisms per total amount of DNA in the sample or per host glyceraldehyde-3-phosphate dehydrogenase copies. The real-time PCR assay for L. (Leishmania) subgenus showed a good linear correlation with quantification on the basis of a limiting dilution assay in experimentally infected mice. The test successfully identifies and quantifies Leishmania in human biopsy specimens and represents a new tool to study leishmaniasis.

Establishment of the comet assay in the freshwater snail Biomphalaria glabrata (Say, 1818)

The single cell gel eletrophoresis or the comet assay was established in the freshwater snail Biomphalaria glabrata. For detecting DNA damage in circulating hemocytes, adult snails were irradiated with single doses of 2.5. 5, 10 and 20 Gy of Co-60 gamma radiation. Genotoxic effect of ionizing radiation was detected at all doses as a dose-related increase in DNA migration. Comet assay in B. glabrata demonstrated to be a simple, fast and reliable tool in the evaluation of genotoxic effects of environmental mutagens. (c) 2008 Elsevier B.V. All rights reserved.

Ultrasensitive Simultaneous Quantification of 1,N(2)-Etheno-2 `-deoxyguanosine and 1,N(2-)Propano-2 `-deoxyguanosine in DNA by an Online Liquid Chromatography-Electrospray Tandem Mass Spectrometry Assay

Exocyclic DNA adducts produced by exogenous and endogenous compounds are emerging as potential tools to study a variety of human diseases and air pollution exposure. A highly sensitive method involving online reverse-phase high performance liquid chromatography with electrospray tandem mass spectrometry detection in the multiple reaction monitoring mode and employing stable isotope-labeled internal standards was developed for the simultaneous quantification of 1,N(2)-etheno-2`-deoxyguanosine (1,N(2)-epsilon dGuo) and 1,N(2)-propano-2`-deoxyguanosine (1,N(2)-propanodGuo) in DNA. This methodology permits direct online quantification of 2`-deoxyguanosine and ca. 500 amol of adducts in 100 mu g of hydrolyzed DNA M the same analysis. Using the newly developed technique, accurate determinations of 1,N(2)-etheno-2`-deoxyguanosine and 1,N2-propano-2`-deoxyguanosine levels in DNA extracts of human cultured cells (4.01 +/- 0.32 1,N(2)-epsilon dGuo/10(8) dGuo and 3.43 +/- 0.33 1,N(2)-propanodGuo/10(8) dGuo) and rat tissue (liver, 2.47 +/- 0.61 1,N(2)-epsilon dGuo/10(8) dGuo and 4.61 +/- 0.69 1,N(2)-propanodGuo/108 dGuo; brain, 2.96 +/- 1.43,N(2)-epsilon dGuo/10(8) dGuo and 5.66 +/- 3.70 1,N(2)-propanoclGuo/10(8) dGuo; and lung, 0,87 +/- 0.34 1,N(2)-edGuo/ 10(8) dGuo and 2.25 +/- 1.72 1,N(2)-propanodGuo/10(8) dGuo) were performed. The method described herein can be used to study the biological significance of exocyclic DNA adducts through the quantification of different adducts in humans and experimental an with pathological conditions and after air pollution exposure.

In vitro basal cytotoxicity assay applied to estimate acute oral systemic toxicity of grandisin and its major metabolite

Preclinical investigations can start with preliminary in vitro studies before using animal models. Following this approach, the number of animals used in preclinical acute toxicity testing can be reduced. In this study, we employed an in-house validated in vitro cytotoxicity test based on the Spielmann approach for toxicity evaluation of the lignan grandisin, a candidate anticancer agent, and its major metabolite. the 4-O-demethylgrandisin, by neutral red uptake (NRU) assay, on mouse fibroblasts Balb/c 3T3 cell line. Using different concentrations of grandisin and its major metabolite (2.31; 1.16; 0.58; 0.29; 0.14; 0.07; 0.04; 0.002 mu M) in Balb/c 3T3-A31 NRU cytotoxicity assay, after incubation for 48 h, we obtained IC(50) values for grandisin and its metabolite of 0.078 and 0.043 mu M, respectively. The computed LD(50) of grandisin and 4-O-demethylgrandisin were 617.72 and 429.95 mg/kg, respectively. Both were classified under the Globally Harmonized System as category 4. Since pharmacological and toxicological data are crucial in the developmental stages of drug discovery, using an in vitro assay we demonstrated that grandisin and its metabolite exhibit distinct toxicity profiles. Furthermore, results presented in this work can contribute to reduce the number of animals required in subsequent pharmacological/toxicological studies. (C) 2010 Elsevier GmbH. All rights reserved.

A preliminary characterization of the mutagenicity of atmospheric particulate matter collected during sugar cane harvesting using the Salmonella/microsome microsuspension assay

During sugar cane harvesting season, which occurs from May to November of each year, the crops are burnt, cut, and transported to the mills. There are reports showing that mutagenic activity and PAH content increase during harvesting season in some areas of Sao Paulo State in comparison with nonharvesting periods. The objective of this work was to preliminarily characterize the mutagenic activity of the total organic extracts as well as corresponding organic fractions of airborne particulate matter (PM) collected twice from two cities, Araraquara (ARQ) and Piracicaba (PRB), during sugar cane harvesting season using the Salmonella/microsome microssuspension assay. One sample collected in Sao Paulo metropolitan area was also included. The mutagenicity of the total extracts ranged from 55 to 320 revertants per cubic meter without the addition of S9 and from not detected to 57 revertants per cubic meter in the presence of S9 in areas with sugar cane plantations. Of the three fractions analyzed, the most polar ones (nitro and oxy) were the most potent. A comparison of the response of TA98 with YG1041 and the increased potencies without S9 indicated that nitro compounds are causing the observed effect. More studies are necessary to verify the sources of the mutagenic activity such as burning of vegetal biomass and combustion of heavy duty vehicles used to transport the sugar cane to the mills. The Salmonella/microsome assay can be an important tool to monitor the atmosphere for mutagenicity during sugar cane harvesting season.

Chemoprotective effect of the tetrahydrofuran lignan grandisin in the in-vivo rodent micronucleus assay

Objectives The chemoprotective effect of the tetrahydrofuran lignan grandisin against DNA damage induced by cyclophosphamide (200 mg/kg) has been evaluated using the in vitro rodent micronucleus assay. Methods The effects of a daily oral administration of grandisin (2, 4, or 8 mg/kg) for five days before exposure to cyclophosphamide on the frequency of micronucleus in the bone marrow of normal mice exposed and unexposed to cyclophosphamide were investigated (n = 5 per group). Electrochemical measurements were applied to investigate whether the antimutagenic effects of grandisin could be, at least in part, a consequence of its or its metabolite`s antioxidant properties. Key findings Grandisin did not show mutagenic effects on the bone marrow cells of exposed mice. On the other hand, the oral administration of grandisin (2, 4, or 8 mg/kg) per day reduced dose-dependently the frequency of micronucleus, induced by cyclophosphamide, in all groups studied. Cyclic voltammograms showed two peaks for a grandisin metabolite, which were absent for grandisin. Conclusions Under the conditions tested herein, this study has shown that mice treated with grandisin presented, in a dose-dependent manner, a protective effect against cyclophosphamide-induced mutagenicity. This effect could be, at least in part, associated to grandisin bioactivation. These data open new perspectives for further investigation into the toxicology and applied pharmacology of grandisin.

Electrochemical determination of the antioxidant capacity: The ceric reducing/antioxidant capacity (CRAC) assay

The CRAC assay is a direct electron transfer test of antioxidant capacity for several organic compounds. The ability of eight different compounds in reducing Cc 41 was studied by chronoamperometric measurements of the remaining Ce(3+) species. The following antioxidant classification was observed: tannic acid >> quercetin > rutin > gallic acid approximate to catechin > ascorbic acid > BHA > Trolox. These results agree with others already published and a good correlation (R(2) = 0.937) was found with the classical spectrophotometric FRAP assay. The CRAC assay is simple, fast, free from sample pretreatment and applicable to nontransparent samples.