Novel application of square-wave adsorptive-stripping voltammetry for the determination of xanthohumol in spent hops

This paper reports the development of a novel electrochemical assay for xanthohumol (XN) by square-wave adsorptive-stripping voltammetry (SWAdSV) with a hanging mercury drop electrode. The method showed good repeatability (CV < 2%) and linearity (between 10 and 250 μg L(-1)), as well as suitable limits of detection (2.6 μg L(-1)) and quantification (8.8 μg L(-1)). The method was applied for the quantification of this compound in spent hops, and the results obtained were compared with the HPLC-UV method. XN contents determined by the SWAdSV method were 16 ± 1 and 100 ± 4 μg L(-1) for aqueous and methanolic extracts, respectively. The developed new methodology considerably reduces the analysis time, approximately from 25 min (HPLC-UV method) to 7 min, enabling a high sample throughput. In addition, the detection and quantification limits were approximately 5-fold lower than those obtained with the chromatographic method.     

Transmission electron microscopy for characterization of acrosomal damage after Percoll gradient centrifugation of cryopreserved bovine spermatozoa

The objective of this study was to characterize acrosomal ultrastructure following discontinuous Percoll gradient centrifugation of cryopreserved bovine sperm. Semen was collected from six bulls of different breeds and three ejaculates per bull were evaluated. Frozen semen samples were thawed and the acrosomal region of sperm cells was evaluated by transmission electron microscopy (TEM) before (n = 18) and after (n = 18) Percoll centrifugation. The evaluation of 20 sperm heads from each of the 36 samples analyzed ensured that a large number of cells were investigated. The data were subjected to analysis of variance at a level of significance of 5%. Percoll centrifugation reduced the percentage of sperm exhibiting normal acrosomes (from 61.77 to 30.24%), reduced the percentage of sperm presenting atypical acrosome reactions (from 28.38 to 4.84%) and increased the percentage of sperm exhibiting damage in the acrosome (from 6.14 to 64.26%). The percentage of sperm with typical acrosome reactions was not significantly different before (3.70%) and after (0.67%) centrifugation. TEM distinguished four different types of acrosomal status and enabled ultrastructural characterization of acrosomal injuries. The percentage of sperm exhibiting normal acrosomes decreased and damage in the acrosome was the most frequent acrosomal injury with the Percoll gradient centrifugation protocol utilized.     

Convergence of developmental mutants into a single tomato model system: 'Micro-Tom' as an effective toolkit for plant development research

Background

The tomato (Solanum lycopersicum L.) plant is both an economically important food crop and an ideal dicot model to investigate various physiological phenomena not possible in Arabidopsis thaliana. Due to the great diversity of tomato cultivars used by the research community, it is often difficult to reliably compare phenotypes. The lack of tomato developmental mutants in a single genetic background prevents the stacking of mutations to facilitate analysis of double and multiple mutants, often required for elucidating developmental pathways.

Results

We took advantage of the small size and rapid life cycle of the tomato cultivar Micro-Tom (MT) to create near-isogenic lines (NILs) by introgressing a suite of hormonal and photomorphogenetic mutations (altered sensitivity or endogenous levels of auxin, ethylene, abscisic acid, gibberellin, brassinosteroid, and light response) into this genetic background. To demonstrate the usefulness of this collection, we compared developmental traits between the produced NILs. All expected mutant phenotypes were expressed in the NILs. We also created NILs harboring the wild type alleles for dwarf, self-pruning and uniform fruit, which are mutations characteristic of MT. This amplified both the applications of the mutant collection presented here and of MT as a genetic model system.

Conclusions

The community resource presented here is a useful toolkit for plant research, particularly for future studies in plant development, which will require the simultaneous observation of the effect of various hormones, signaling pathways and crosstalk.     

Source of polynuclear aromatic hydrocarbons found in sediment in a region of expanding sugarcane cultivation of São Paulo State,Brazil

Purpose

Polycyclic aromatic hydrocarbons (PAHs) are unintentional products that are classified as persistent toxic substances. The goal of the present study was to generate data on the presence of 15 priority PAHs that are found in surface sediment and core sediment in the region of the Turvo/Grande watershed, São Paulo State, Brazil, which is an area of expanding sugarcane cultivation, and to correlate these data with the sources of these PAHs and the guiding values for sediment quality analysis.

Materials and methods

Surface sediments and sediment cores were sampled during the rainy and dry seasons in February and July 2010. The extraction of PAHs from sediments was performed using a Soxhlet extractor, and then the extract was cleaned according to the methods of the US EPA 3630C (US EPA 1996) using a silica gel column. Quantification was performed using high performance liquid chromatography with fluorescence detection.

Results and discussion

The concentrations of all 15 PAHs decreased as the depth of the sediment core increased. Overall, the concentrations decreased along the sediment core; however, the RTURARG (region predominantly used for planting sugarcane and livestock) during the rainy season and the CAPRP sampling site (located at part of the Preto River dam) during the dry season showed increased concentrations in the first few sediment fractions, and then the concentrations decreased. Higher concentrations were observed in urban locations, and the concentration of naphthalene was higher than the probable effect level (PEL) determined by the Canadian environmental agency. The obtained diagnostic ratios indicate that the sediment from areas with an abundance of sugarcane was a pyrolytic source of PAHs, which indicates a contribution from burning straw to the PAH concentrations in those areas.

Conclusions

For all sampling sites and all PAHs, we found a decreasing trend in PAH concentrations with increasing sediment core depth, and the locations, such as CAPRP, that experienced a higher level of human activity had the highest total concentrations of PAHs. These locations were the only areas in which the PAH naphthalene was found in higher concentrations than the PEL. The diagnostic ratios reveal that regions with sugarcane plantations had predominantly pyrolytic sources of PAHs, indicating the contribution of PAHs from sugarcane straw burning.

     

Linalool from Lippia alba: study of the reproducibility of the essential oil profile and the enantiomeric purity

A new chemotype of the aromatic Verbenaceae species Lippia alba Mill. N. E. Br. from southeastern Brazil has recently been shown to have a high content of linalool in the leaf essential oil. Vegetative propagation of this chemotype was conducted at six different locations in Brazil, and the variation of the content and the optical purity of linalool in the oils were verified. Yields (0.6-0.9%, hydrodistillation), chemical composition, linalool content, and optical purity of the oils from all the plants were compared, using GC-FID, GC-MS, chiral chromatography, and retention index calculation. No plant exceeded the matrix in linalool content (46.5 to 90.7%), and the chemical profile of the oils was the same for all the samples. Purification of linalool to a content close to 100% was effected by vacuum distillation of the crude oil. Chiral analysis showed exclusively the presence of S-linalool in all the crude oils and in the distilled samples.     

Stabilization of soybean oil with heated quercetin and 5-caffeoylquinic acid in the presence of ferric ion

The effect of heated quercetin (400 mg/kg of oil) or 5-caffeoylquinic acid (5-CQA) and the presence of ferric ion (2.2 mg/kg of oil) on the stability of soya oil oxidized in an oxidative stability index (OSI) instrument was investigated. After heating the phenolic at 100 degrees C or 150 degrees C, the OSI values of treated oils were not significantly (p < 0.001) different, whereas, at 200 degrees C, the values decreased significantly with addition of quercetin, but not with 5-CQA. However, the antioxidative activity of quercetin remained significantly greater than that of 5-CQA. The antioxidative potency of quercetin was reduced significantly by addition of ferric palmitate (FP), but that of 5-CQA was not. Reaction between the ortho-dihydroxy groups of the quercetin and ferric ion may reduce the number of hydroxyls available to react with free radicals. Chelating action of 5-CQA might be provided by ortho-dihydroxy grouping of the quinic acid moiety.     

Generation of a Mixolab Profile After the Evaluation of the Functionality of Different Commercial Wheat Flours for Hot‐Press Tortilla Production

Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas.     

Modelling soil-water-plant relationships in the Cerrado soils of Brazil: The case of maize (Zea mays L.)

A soil-water balance simulation model developed for the Cerrado soils of central Brazil is presented. The model calculates daily soil water evaporation, plant transpiration and soil-water balance for fourteen soil layers of 15 mm each. The model includes a subroutine to calculate capillary water movement. Computer simulations of daily soil water levels at five soil depths (15, 30, 45, 60 and 90 cm) for a field of maize are compared with actual field measurements over an 80-day period. Results indicated that the developed model can, in general, estimate the soil-water balance of the various depths within ± 10% of actual measurements.     

A PCR technique for the detection of Jaagsiekte sheep retrovirus in the blood suitable for the screening of ovine pulmonary adenocarcinoma in field conditions

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring contagious lung neoplasia caused by jaagsiekte sheep retrovirus (JSRV). Although no specific circulating antibodies against the virus can be detected in infected sheep, JSRV proviral DNA sequences can be found in peripheral blood leukocytes (PBLs) in clinically affected and in a proportion of in contact animals. In this study, existing hemi-nested PCR procedure is compared with a new one-step PCR technique that was developed to minimise potential DNA contamination and reduce sample and reagent handling. Different blood preparations were assessed and the best results were achieved on DNA prepared from buffy coat. The sensitivity of this PCR was lower in JSRV infected sheep without lesions of OPA than in clinically affected sheep, which indicate that this PCR may not be not fully appropriate for screening of individual sheep, but rather to provide results at flock level. This PCR is the only currently available blood test for detection of JSRV infected sheep and may be useful in epidemiological studies and in control programmes of OPA.     

Evaluation of the internal vertebral venous plexus, vertebral canal, dural sac, and vertebral body via nonselective computed tomographic venography in the cervical vertebral column in healthy dogs

OBJECTIVE: To evaluate nonselective computed tomographic (CT) venography for evaluating the cervical internal vertebral venous plexus (IVVP), define the diameter and area dimensions of the IVVP, and determine the relationship between dimensions of the cervical IVVP and other vertebral components in medium-sized dogs. Animals-6 healthy dogs that weighed 18 to 27 kg. Procedure-Helical CT scans were performed from C1 to C7 before and after IV injection of contrast medium (480 mg of iodine/kg) and a continuous infusion (240 mg of iodine/kg). Image data were transferred to a CT workstation, and measurements were performed on displayed transverse images. Diameter and area measurements of the vertebral canal, dural sac, IVVP, and vertebral body were obtained at C3 to C7. RESULTS: Opacification of vertebral venous structures was achieved in all dogs with no adverse reactions. Sagittal diameters of the IVVP for C3 to C7 ranged from 0.6 to 3.2 mm. Transverse diameters ranged from 2.32 to 5.74 mm. The IVVP area represented 12.4% of the mean vertebral canal transverse area and 30.61% of the mean vertebral epidural space area. Area measurements of the IVVP were significantly correlated with vertebral canal area and dural sac area. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that nonselective CT venography is a safe, sensitive method for performing morphometric assessments of the cervical IVVP in dogs. Findings support the theory that there may be a physiologic or developmental relationship between cervical vertebral canal components.