Effects of different variable sets on the potential distribution of fish species in the Amazon Basin

Estimating species’ potential distribution is one of the main objectives of macroecology, especially when sampling biases can affect knowledge on how environmental variables affect species distribution. Ecological niche models estimate species’ environmental niches from different variables and their occurrences. Using the presence-only data from eight Amazonian fish species, which inhabit rivers and streams, we aimed to (a) explore the effect of different sets variables on the spatial distributions of target species and (b) evaluate the predictive responses of MaxEnt to sets of variables with different degrees of complexity. MaxEnt has high flexibility in relation to the input data and its performance is influenced by a moderate number of adjustable parameters, allowing for high precision results when balancing underestimation and overestimation errors. We used environmental predictors in MaxEnt the principal components of climatic, topographic and edaphic variables as inputs. The combination of topographic and edaphic variables produced more precise and spatially restricted distribution ranges for all species when compared to those generated with climatic variables. All models reached high AUC values, especially for stream species. Modelled range sizes were broader for the river species, suggesting different tolerance thresholds and habitat preferences when compared to stream species. The complexity of the different variables sets did not affect MaxEnt's prediction capacity. However, for stream species, MaxEnt showed a greater predictive power. This work increases the knowledge with regards to the influence of different environmental predictors on the spatial patterns of the distribution of Amazonian fish.     

Detection of Escherichia coli Serotype 0157 in Beef Carcasses and Faecal Material

Veterinary Research Communications -     

FASTING-INDUCED CHANGES TO THE PHARMACOKINETIC BEHAVIOUR OF ALBENDAZOLE AND ITS METABOLITES IN CALVES

The influence of fasting on the bioavailability and disposition kinetics of albendazole (ABZ) and its metabolites in cattle was investigated. ABZ (10 mg/kg) was given by intraruminal (i.r.) (Experiment 1) and intravenous (i.v.) (Experiment 2) administration to Holstein calves either fed ad libitum (control) or subjected to a 48 h fasting period (fasted group) prior to treatment. The rate of passage of digesta through the gastrointestinal (GI) tract was evaluated by measurement of cobalt faecal excretion following the oral administration of the sodium-cobalt-ethylendiamine-tetracetic acid complex to calves subjected to the feeding conditions above described. Jugular blood and abomasal fluid (via cannula) samples were collected over 120 h post-treatment; samples were analysed by high performance liquid chromatography (HPLC) for ABZ, ABZ sulphoxide (ABZSO) and ABZ sulphone (ABZSO₂). Fasting the animals prior to the i.r. treatment resulted in pronounced modifications to the plasma and abomasal fluid disposition kinetics of ABZ and its metabolites. A greater extent of GI absorption with significantly higher C_max (150%) and AUC (310%) values for ABZSO in plasma, was observed in fasted compared to fed animals following the i.r. administration of ABZ. Extended detection of ABZ metabolites resulting in significantly longer plasma t_½el and MRT was also obtained in fasted compared to fed calves. These results correlated with the substantially enhanced availability of ABZ and its metabolites (AUCs over 200% greater) in the abomasal fluid of the fasted animals. Fasting did not induce changes to the plasma disposition of either ABZ or its metabolites after the i.v. treatment. The digesta passage rate, measured by the amount of cobalt excreted in faeces, was significantly lower in fasted compared to animals fed ad libitum. A delayed GI transit time that decreases the rate of passage of the drug down the digestive tract, may have accounted for enhanced ABZ dissolution and absorption in fasted compared to fed calves. The findings reported in this article show that fasting prior to treatment notably affects the bioavailability and disposition kinetics of ABZ and its metabolites in cattle.     

Mechanism of inhibition of lipid peroxidation by gamma-terpinene,an unusual and potentially useful hydrocarbon antioxidant

gamma-Terpinene (TH), a monoterpene hydrocarbon present in essential oils, retards the peroxidation of linoleic acid (LH). The peroxidation of TH has been shown to yield p-cymene as the only organic product in a chain reaction in which the chain carrier is the hydroperoxyl radical, HOO(.). The peroxidation of LH is well-known to be a chain reaction in which the chains are carried by linoleylperoxyl radicals, LOO., and the products are linoleyl hydroperoxides. The retardation of LH peroxidation by TH has been found to be due to rapid chain termination via a very fast cross-reaction between HOO. and LOO. radicals. This antioxidant mechanism is completely different from the mechanism of antioxidant action of vitamin E. Since vitamin E becomes a prooxidant at high concentrations, the addition of essential oils containing TH to edible lipids may provide an alternative or supplementary strategy for obtaining large increases in their oxidative stability and shelf life, something that cannot be achieved by simply adding more and more vitamin E.     

Influence of automatic dishwashings and scrubbings on release of lead from glazed ceramicware

Use of lead glazes on ceramicware and the release of lead from finished glazes are reviewed. Single units of ceramicware with initial lead leach levels from less than 0.1 to 470 micrograms/mL were subjected to multiple automatic dishwashings with intermediate scrubbing of the ware by plastic fiber pads. Ware was periodically leached with 4% acetic acid solution at room temperature for 24 h, and the solutions were analyzed for lead. Release of lead under these conditions is discussed. Results indicated that neither passive leachings nor multiple dishwashings and scrubbings can predict future lead-release characteristics of glazes and decorations.     

Effects of zinc complexes on the distribution of zinc in calcareous soil and zinc uptake by maize

The movement and availability of Zn from six organic Zn sources in a Typic Xerorthent (calcareous) soil were compared by incubation, column assay, and in a greenhouse study with maize (Zea mays L.). Zinc soil behavior was studied by sequential, diethylenetriaminepentaacetate, and Mehlich-3 extractions. In the incubation experiment, the differences in Zn concentration observed in the water soluble plus exchangeable fraction strongly correlated with Zn uptake by plants in the greenhouse experiment. Zinc applied to the surface of soil columns scarcely moved into deeper layers except for Zn-ethylenediaminetetraacetate (EDTA) that showed the greatest distribution of labile Zn throughout the soil and the highest proportion of leaching of the applied Zn. In the upper part of the column, changes in the chemical forms of all treatments occurred and an increase in organically complexed and amorphous Fe oxide-bound fractions was detected. However, the water soluble plus exchangeable fraction was not detected. The same results were obtained at the end of the greenhouse experiment. Significant increases were found in plant dry matter yield and Zn concentration as compared with the control treatment without Zn addition. Increasing Zn rate in the soil increased dry matter yield in all cases but Zn concentration in the plant increased only with Zn-EDTA and Zn-ethylenediaminedi-o-hydroxyphenyl-acetate (EDDHA) fertilizers. Higher Zn concentration in plants (50.9 mg kg(-)(1)) occurred when 20 mg Zn kg(-)(1) was added to the soil as Zn-EDTA. The relative effectiveness of the different Zn carriers in increasing Zn uptake was in the order: Zn-EDTA > Zn-EDDHA > Zn-heptagluconate >/= Zn-phenolate approximately Zn-polyflavonoid approximately Zn-lignosulfonate.     

Carbon in heartwood,sapwood and bark along the stem profile in three Mediterranean <Emphasis Type="Italic">Pinus</Emphasis> species

• Context   

Understanding biological processes in forests is necessary to orientate ecosystem management towards potential C sequestration. To achieve this, information is required about changes in forest biomass C pools, including the stem components (bark, sapwood and heartwood).     

Genetic diversity of Syrian pistachio (<Emphasis Type="Italic">Pistacia vera</Emphasis> L.) varieties evaluated by AFLP markers

Pistachio (Pistacia vera L.) is a strategic nut tree species in the Middle East which holds comparative advantage over other fruit trees in view of its hardiness, income generation opportunities and benefits for the ecosystem. Yet pistachio cultivation depends on a very narrow genetic base, in spite of the existence of many varieties still marginally exploited. Syria is an important center of diversity for pistachio. A country wide ecogeographic survey in this country was carried out to determine the extent of pistachio genetic diversity and its use. As a whole, 114 accessions were collected from 37 farms to assess diversity at morphological and molecular level. Molecular evaluation was carried out using Amplified Fragment Length Polymorphism (AFLP) technique and performed using seven primer pair combinations. Results from the studies allowed the identification of 25 pistachio female varieties in Syria, some of which unique and described for the first time. Three groups of pistachio diversity were identified by cluster analysis which provides useful information about the distribution of genetic diversity in Syria for enhanced use and sustainable conservation.     

Dissolved and Particulate Heavy Metals in the Salado River (Santa FE, Argentina)

The objective of this work is to analyze Fe, Mn, Cr, Cd, Cu, Pb, and Zn distributions in the water column in terms of total, dissolved, and particulate concentrations in the Salado River (Santa Fe – Argentina); their relationship with total, dissolved and suspended solids; and the impact of two pollution sources on the watercourse: a stream that collects domestic and industrial wastewater discharges of the region and a direct discharge that releases urban and industrial effluents to the river. Water samples obtained from 5 surveys were analyzed. The Salado River transported a load of heavy metals that ranged from 700 g/s to 2200 g/s of Fe, 20 g/s to 60 g/s of Mn and 1 g/s to 3 g/s of Cr. Results show that most metals were found in particulate form, that the metal input from the direct discharge may be significant at low water levels, whereas a lesser impact was produced by the stream, and that both pollution sources were negligible at high water levels.