Distribution of the Mallorcan midwife toad (Alytes muletensis) in relation to landscape topography and introduced predators

The endemic midwife toad of Mallorca (Alytes muletensis) is restricted to a small number of breeding populations in the mountainous northwest of the island. The decline of the species has been attributed to the impacts of introduced species such as the viperine snake (Natrix maura) and green frog (Rana perezi), and toads may be surviving only in areas that are suboptimal for these predators. The influence of landscape features (elevation, aspect and maximum slope) on the distribution of toads and associated predators was therefore investigated using GIS. The presence of toads was positively associated with steep slopes. At sites where they occurred with toads, the distribution of predators was negatively associated with elevation. Reproductive success within toad populations was strongly associated with the number of pools at each site, while reproductive success within individual pools was positively associated with elevation. These findings may be used to optimise the design and location of future reintroduction sites.     

Changes in amine concentrations during aging of red wine in oak barrels

This investigation studied the evolution of amines in red wines made with Merlot variety, during aging in American oak barrels (Quercus alba) and in French oak barrels (Quercus sessilis) from the Allier and Nevers regions. From the results obtained it was observed that the evolutions of the amines were similar in all three types of oak woods. Histamine and tyramine were produced at the beginning of the aging process, although they were not accumulated in the wines, probably due to their degradation. Putrescine was the most abundant amine in the wines; its concentration increased to an important extent during aging as it did not undergo degradation. The concentration of cadaverine increased slightly at the first stage of aging and, like putrescine, did not degrade at all. The volatile amines showed slight variations during aging, although in no cases were high accumulations observed in the wines. Dimethylamine and isobutylamine were degraded during storage in the barrels.     

Rapid quantitative assessment of the adulteration of virgin olive oils with hazelnut oils using Raman spectroscopy and chemometrics

The authentication of extra virgin olive oil and its adulteration with lower-priced oils are serious problems in the olive oil industry. In addition to the obvious effect on producer profits, adulteration can also cause severe health and safety problems. A number of techniques, including chromatographic and spectroscopic methods, have recently been employed to assess the purity of olive oils. In this study Raman spectroscopy together with multivariate and evolutionary computational-based methods have been employed to assess the ability of Raman spectroscopy to discriminate between chemically very closely related oils. Additionally, the levels of hazelnut oils used to adulterate extra virgin olive oil were successfully quantified using partial least squares and genetic programming.     

Persistence of simazine and terbuthylazine in a semiarid soil after organic amendment with urban sewage sludge

The persistence of two herbicides, simazine and terbuthylazine, and appearance of their principal dealkylated chloro-s-triazine metabolites have been studied in agricultural soil after the addition of urban sewage sludge as organic amendment. Both herbicides and metabolites were monitored during long-term laboratory incubation (140 days) and analyzed by gas chromatography with a nitrogen-phosphorus detector (GC-NPD). Residues were confirmed by gas chromatography with a mass selective detector (GC-MSD). A sonication microextraction method was used to extract the compounds. The organic amendments used were urban sewage sludge and the humic fraction of this sludge, to increase the organic matter content of the soil from 1% to 2%. For both compounds, simazine and terbuthylazine, the degradation began earlier in the amended soils. Simazine showed a higher dissipation rate than terbuthylazine, the percentage of the former at the end of the experiment being lower than 2% in all cases, while for terbuthylazine the corresponding percentage ranged from 5% to 46%. Organic amendment, mainly its humic fraction, caused a certain stabilization of terbuthylazine in the soil, but did not greatly influence the residual amount of simazine at the end of the experiment. The periodic aeration of the soil caused a greater degradation in the case of terbuthylazine. Only mono-deethylsimazine and deethylterbuthylazine were isolated from the soil during the time the experiment lasted, while the di-deethylated metabolite of simazine was not found.     

Relationship between cyanogenic compounds in kernels, leaves, and roots of sweet and bitter kernelled almonds

The relationship between the levels of cyanogenic compounds (amygdalin and prunasin) in kernels, leaves, and roots of 5 sweet-, 5 slightly bitter-, and 5 bitter-kernelled almond trees was determined. Variability was observed among the genotypes for these compounds. Prunasin was found only in the vegetative part (roots and leaves) for all genotypes tested. Amygdalin was detected only in the kernels, mainly in bitter genotypes. In general, bitter-kernelled genotypes had higher levels of prunasin in their roots than nonbitter ones, but the correlation between cyanogenic compounds in the different parts of plants was not high. While prunasin seems to be present in most almond roots (with a variable concentration) only bitter-kernelled genotypes are able to transform it into amygdalin in the kernel. Breeding for prunasin-based resistance to the buprestid beetle Capnodis tenebrionis L. is discussed.     

Principal component analysis of biogenic amines and polyphenols in Hungarian wines

Biogenic amines, polyphenols, and resveratrol were analyzed quantitatively in 25 different Hungarian wines from the same wine-making region, harvest of 1998. Polyphenols were determined according to a spectrophotometric method, whereas other substrates were analyzed using overpressured-layer chromatography (OPLC). Principal component analyses (PCA) were performed on data matrices consisting of substrates (columns) and different sorts of wines (rows) from the region of Pécs (southern Hungary). It was found that four (unrotated) principal components account for >80% of the total variance in the data. The plots of component loadings showed significant groupings for concentrations of biogenic amines (and polyphenols). Similarly, the component scores grouped according to the different sorts of wines. The loading plots reveal that there is no need to measure all of the variables to achieve the same characterization. It is enough to measure one variable per group. Naturally, this conclusion is valid only within the limits of the present study; wines from other regions may behave differently.     

Furosine as indicator of maillard reaction in jams and fruit-based infant foods

To investigate the presence of furosine in commercial samples of jams and fruit-based infant foods a simple method by ion-pair reversed-phase liquid chromatography is described. The yield of furosine during the hydrolysis with hydrochloric acid was optimized. The reproducibility in the repeatability and recovery of the method, expressed in relative standard deviation percentages, proved to be in the ranges of 4.1-8.3% and 1.0-4.4%, respectively. The recovery percentages of furosine varied between 86.7 and 95.3%. The obtained results support the suitability of the method. Furosine was detected in all studied samples. Although a high variability in the content of furosine was noticed, in general terms, the lowest levels of furosine were observed in samples of fruit-based infant foods and the highest were observed in jams of more than 60% sugar. These results could be due to different heat treatment, storage conditions, and/or differences in the values of water activity (a(w)) and amounts of sugar. The results obtained in the present paper point out the usefulness of furosine as an indicator of Maillard reaction for jams and fruit-based infant foods.     

Ultrasensitive detection of genetically modified maize DNA by capillary gel electrophoresis with laser-induced fluorescence using different fluorescent intercalating dyes

In this work, four different fluorescent intercalating dyes are compared for the ultrasensitive CGE-LIF detection of DNA from transgenic maize in flours. The fluorescent intercalating dyes compared are YOPRO-1, SYBR-Green-I, Ethidium bromide (EthBr), and EnhanCE. For all the four dyes optimum concentrations are established, and efficient separations of DNA fragments ranging in size from 80 to 1000 bp are obtained. The comparative study demonstrates that SYBR-Green-I and YOPRO-1 provide better limits of detection (LODs) than EnhanCE or EthBr (i.e., LODs are, respectively, 700, 1000, 11300, and 97400 zmol, calculated for a 200-bp DNA fragment). Separations using YOPRO-1 are faster than those using SYBR-Green-I (30 min vs 47 min for the analysis of the 80-1000 bp DNA fragments). Also, separations using YOPRO-1 are more efficient than those using SYBR-Green-I (e.g., 2.4 x 10(6) plates/m vs 1.6 x 10(6) plates/m, respectively, calculated for the 200-bp fragment). Also, buffer depletion and cost per analysis are worse with SYBR-Green-I than with YOPRO-1. Therefore, YOPRO-1 was selected as the preferred intercalating dye. Using this fluorescent compound, analysis time reproducibility for the CGE-LIF separation of the DNA fragments is determined to be better than 1.7% (% RSD, n = 10) within the same day, and better than 1.9% (% RSD, n = 30) for three different days. Moreover, the fluorescence signal obtained using this dye is shown to vary linearly with the DNA concentration in the range studied, i.e., 1-500 ng/microL. It is demonstrated that by using this method 0.01% of transgenic maize can be detected in flour by direct injection of the PCR-amplified sample.     

Seasonal patterns of root-surface phosphatase activities in a Mediterranean shrubland. Responses to experimental warming and drought

Mediterranean ecosystems are water limited and the current general circulation Models (GCM) and ecophysiological models forecast a warming and a further increase of drought in the next decades. A stronger water stress can decrease the capacity for nutrient absorption by plants. We conducted a field experiment to simulate forecasted drought and warming in a Mediterranean calcareous shrubland to assess the performance of root-surface phosphatase activities of the dominant shrub Globularia alypum. These enzyme activities were higher in autumn and spring, when the climate conditions were optimal for plant activity, than in summer or winter, when there was either lack of water or cold temperatures. A decrease in soil moisture in drought plots decreased root-surface phosphatase activity (29% in summer and 25% in autumn). The decrease in root-surface phosphatase activity in drought plots coincided with a decrease in P leaf concentrations and P accumulation in aboveground biomass and loss of photosynthetic capacity of some dominant shrub species of this ecosystem, and with a tendency to increase total soil-P. These results suggest that the expected drier conditions in this Mediterranean shrubland in the next decades will slow down the P uptake by plants, thereby, diminishing the P contents in biomass and increasing total P contents in soil in non-available forms and that this can be, in part, attributable to a result of the decrease in root-surface phosphatase activity.     

Temporal and Spatial Monitoring of the pH and Heavy Metals in a Soil Polluted by Mine Spill. Post Cleaning Effects

The bursting of the mining dam of Aznalcollar (Seville, Spain) triggered an increase in the concentration of heavy metals in the soils of the river Guadiamar valley as a result of the leaching of the pyritic sludge deposited on them. After the cleaning operations which included, as well as mechanical clearing, the addition of different amendments, some areas with residual sludge remained, from which some heavy metals are being mobilized by the cyclical recharge and discharge processes of water in the profiles. This paper analyzes the effect of the soil recovery operations and the climatology on the concentration of metals and their distribution in the soil profile in an area affected by the toxic spill. Fourteen points have been selected in a plot in which acidity persists, there is no vegetation, and residual sludge stains can be seen at a glance. The temporal and spatial evolution of the extractable metals: Fe, Cu, Mn and Zn, the pH and the oxidable fraction has been measured in-depth. The results obtained up to now indicate a leaching of the pollutant towards deeper horizons, finding, at a depth of 757 cm, pH values of 3.5 and very high Fe and Mn concentrations available, especially in the profiles with large sized pores, with a big fraction of sand. On the surface, seasonally, there are low pH values of around 2.5 and extractable Fe contents of over 4000 ppm, which might have an influence on the quality of surface runoff or underground water.