Characterization of phytoecdysteroid glycosides in Meadowfoam (Limnanthes alba) seed meal by positive and negative ion LC-MS/MS

Meadowfoam ( Limnanthes alba) is an oilseed crop grown in western Oregon. The seed meal has potential value as a biopesticide due to glucosinolate degradation products and phytoecdysteroids, a group of polyhydroxylated triterpenoids with potent activities as arthropod molting hormones. Liquid chromatography in combination with tandem mass spectrometry operated in the precursor ion mode revealed the presence of four ecdysteroid glycosides in meadowfoam seed meal. The carbohydrate sequence and the identity of the ecdysteroid aglycones, ponasterone A and 20-hydroxyecdysone, were determined by product ion scanning. Ecdysteroids were detected in the negative ion mode as [M + formate] (-) ions, which yielded [M - H] (-) and alpha-cleavage fragments with retention of hydroxyl groups in MS/MS experiments (not seen in the positive ion mode), allowing the determination of the number of hydroxyl groups in the side chain and in the steroid ring system. MS/MS of glycoside ions ([MH] (+) or [M + formate] (-)) provided carbohydrate sequence information.     

Technique for rapid, small-scale analysis of vitamin C levels in fruit and application to a tomato mutant collection

We present a technique for easy, rapid analysis of both total and reduced forms of vitamin C in fruits using microplates and a plate reader. This technique has been compared with a spectrofluorometric technique classically used for assaying vitamin C in fresh tomato. We have applied these methods to a population of 118 tomato mutant lines and controls in search of variability for this trait. Six lines, identified as having high vitamin C levels, and four lines having low vitamin C levels have been chosen for further study. The vitamin C levels have been compared with sugar concentration, dry matter content, fruit weight, titratable acidity, and firmness. The correlations that often exist in tomato varieties between sugar and vitamin C content (positive correlation) or fruit weight and vitamin C content (negative correlation) can be uncoupled in the lines selected for further analysis.     

Sources of nitrite in a permanent grassland soil

The objective of this study was to separate the observed nitrite (NO₂^–) concentration in a permanent grassland soil into process‐specific subpools. A laboratory experiment was carried out where either the nitrate and/or ammonium pool was labelled with ¹⁵N at 60 atom % excess. The main N transformations that occurred in this experiment were analysed with a ¹⁵N tracing model extended with a NO₂^– submodel. Techniques that have been used to date have been only able to identify NO₂^– subpools related to nitrification (NO₂^–_nit) and denitrification (NO₂^–_den). With the analysis presented here, we were able to quantify the size of an additional NO₂^– pool in the soil related to organic N turnover (NO₂^–_org). All transformations related to NO₂^– turnover of the three subpools occurred simultaneously. After non‐linear parameter optimization the model predicted that on average NO₂^–_den, NO₂^–_nit and NO₂^–_org pools contributed 57, 33 and 10% to the total soil NO₂^– concentration. The finding that heterotrophic processes can contribute to the NO₂^– dynamics in permanent grassland soils might also have important implications for the understanding of gaseous N production that are tightly linked to NO₂^– turnover. Further work is needed to find out how important the conversion of organic N to NO₂^– is in other soil‐based ecosystems and to identify the microbial groups responsible for this process.     

Breast cancer prevention by green tea catechins and black tea theaflavins in the C3(1) SV40 T,t antigen transgenic mouse model is accompanied by increased apoptosis and a decrease in oxidative DNA adducts

Tea consumption is associated with a reduced risk of mammary cancer as reflected by epidemiological studies and experiments in carcinogen-induced rodent models of mammary carcinogenesis. We tested the hypothesis that green tea catechins (GTC) or theaflavins from black tea (BTT) interfere with mammary carcinogenesis in C3(1) SV40 T,t antigen transgenic multiple mammary adenocarcinoma (TAg) mice and that GTC/BTT affect tumor survival or oxidation status. TAg mice received GTC/BTT (0.05%) in drinking water for their lifetime. As compared to control mice, they survived longer and had smaller tumors. On microscopic inspection, the size of the largest tumor per mouse was decreased by 40-42% (p<0.01). GTC (0.01%) and BTT (0.05%) increased levels of cleaved caspase 3 in tumor tissue by 67 and 38%, respectively (p<0.05), intimating increased apoptosis. Tumor levels of the malondialdehyde-DNA adduct M1dG in mice receiving GTC or BTT (0.05%) were reduced by 78 (p<0.001) or 63% (p<0.05), respectively, as compared to controls. The results render the exploration of the breast cancer chemopreventive properties of tea preparations in humans worthwhile.     

Transformation and sorption of fipronil in urban stream sediments

Fipronil is an urban-use insecticide, and the increased use has led to its frequent detections in urban streams. Most studies on the environmental fate of fipronil so far have focused on soils, and little is known about its behavior in sediment-water systems. In this study, we investigated the transformation and sorption of fipronil in urban stream sediments from California, incubated under facultative and anaerobic conditions. Degradation of fipronil in sediments generally followed exponential decay kinetics, and the first-order half-lives of fipronil were only 4.6-18.5 days in anaerobic sediments. The persistence of fipronil under facultative conditions was considerably longer, with half-lives from 25 to 91 days. Sterilization generally decreased the dissipation of fipronil, indicating that microbial activity was an important factor in fipronil transformations in sediments. Under facultative conditions, fipronil sulfide and sulfone were observed, while only fipronil sulfide was detected in anaerobic samples. The sorption coefficient K d consistently increased with organic carbon contents of sediments. In the same sediment, K d usually also increased with contact time, suggesting decreased availability for aged residues. Results from this study showed that the stability of fipronil in sediments depends closely on the oxygen status and that due to the readily conversion of fipronil to the sulfone and sulfide metabolites, the overall risk assessment of fipronil in surface aquatic systems should take into consideration fipronil as well as its metabolites.     

Beaver (Castor canadensis) as a surrogate species for conserving anuran amphibians on boreal streams in Alberta, Canada

We explored the use of beaver (Castor canadensis) as a surrogate species for amphibian conservation on small (1st-4th-order) streams in the Boreal Foothills of west-central Alberta. Anuran call surveys indicated that beaver create breeding habitat for the boreal chorus frog (Pseudacris maculata), wood frog (Rana sylvatica) and western toad (Bufo boreas). No calling males of any species were recorded on unobstructed streams. Wood frog, the most abundant species, exhibited high rates of juvenile recruitment on beaver ponds. Pitfall traps captured more wood frogs on beaver ponds versus unobstructed streams, and most individuals (84%) were young-of-year. Abundance of young-of-year was strongly correlated with percent landscape occupied by beaver ponds indicating that anurans captured along streams originated in beaver ponds. Based on a novel combination of a digital elevation model and aerial photographs examined with GIS, statistical models showed that the probability of beaver pond occurrence on streams was positively associated with stream order and dependent on the interacting effects of distance to nearest forestry cutblock and availability of beaver foods (Populus spp.). We propose that the distribution and abundance of beaver ponds could be determined over large areas quickly and inexpensively by remote sensing and used to identify and monitor amphibian habitat, and possibly, populations. This work establishes the pre-eminence of beaver-created wetlands as amphibian habitat in the Boreal Foothills and that the incorporation of dam-building patterns into forest management strategies could aid amphibian conservation.     

Tepoxalin reduces pruritus and modified CADESI-01 scores in dogs with atopic dermatitis: a prospective, randomized, double-blinded, placebo-controlled, cross-over study

Thirty dogs with atopic dermatitis were given tepoxalin (Zubrin®, Intervet/Schering-Plough Animal Health, Boxmeer, the Netherlands) or placebo once daily for 4 weeks, followed by a wash-out period of 1 week before reversing the treatments. Pruritus was scored by the owners using the Edinburgh Pruritus Scale and one investigator employed a modification of the Canine Atopic Dermatitis Extent and Severity Index-01 (mCADESI-01) to score the physical lesions. After administration of tepoxalin there was a ≥ 50% reduction in pruritus and mCADESI-01 scores in 36% and 25% of the dogs, respectively, whereas following administration of the placebo there was a ≥ 50% reduction in pruritus and mCADESI-01 scores in only 25% and 16% of the dogs, respectively. Analysis of pooled data indicated that tepoxalin resulted in a significant reduction in pruritus ( P  = 0.012) and mCADESI-01 ( P  = 0.002) scores but there was no significant change after placebo. The median pruritus scores before and after tepoxalin were 2 (range 1–5) and 1 (range 0–5), respectively, and before and after placebo were 2 (range 0–4) and 2 (range 0–4), respectively. The median mCADESI scores before and after tepoxalin were 23 (range 0–68) and 16 (range 0–72), respectively, and before and after placebo were 18 (range 3–79) and 24 (range 0–65), respectively. At the dose used in this study (10.0–19.1 mg kg⁻¹), tepoxalin was well-tolerated and no adverse effects were noted.     

Farm-level factors associated with above-average production on pig farms in Evia, Greece

The aim of this study was to identify farm-level factors associated with above-average production of pig farms in Evia, Greece. Cross-sectional data on pig farm characteristics and management, farmer characteristics, worming practices, anthelmintics used, and the parasite loads of 10 randomly selected boars, sows, weaners, and fatteners were collected from 28 pig enterprises in the Evian region of Greece (74% of the total number of pig enterprises in this region). Above-average productivity was defined as weaning 18 or more piglets per sow per year. A multivariate logistic regression model found that employing immigrant workers reduced the odds of a farm being an above-average producer (OR 0.016, 95% CI 0.001–0.27), while having a veterinarian select the anthelmintic strategy significantly increased the odds of a farm being an above-average producer (OR 10.24, 95% CI 0.78–135.13). None of the gastrointestinal parasites under investigation were significantly associated with above-average productivity. It is concluded that despite the fact that endoparasite load was not significantly associated with above-average production, a quantification of the impact of intestinal worms on pig productivity is needed to know how much control can be envisaged for gastrointestinal worms before reaching the threshold at which it is no longer physically or financially reasonable to continue pursuing control.