<Emphasis Type="Italic">Asthenes dorbignyi</Emphasis> (Passeriformes: Furnariidae) host of <Emphasis Type="Italic">Argas neghmei</Emphasis> (Acari: Argasidae)

Argas neghmei Kohls & Hoogstraal is a Neotropical tick species parasite of poultry and man in the arid western of the southern cone of America in Argentina and Chile. Males, females and nymphs of an argasid were collected from 20 to 22 of June, 2007 in nests of Creamy-breasted Canastero, Asthenes dorbignyi (Reinchenbach) (Passeriformes: Furnariidae) at about 7 km S of La Poma (24°46′S, 66°12′W) and a male tick at 24°48′S, 66°10′W on Nov 27, 2008, Salta province, Argentina. Scanning electron microscope micrographies and sequences of 16S rDNA confirmed that the ticks found were A. neghmei. Development in breeding areas of A. dorbignyi is probably a source of infestation for animal premises and houses. However, the role of other unknown wild birds may also contribute to the invasion of A. neghmei in chicken houses or residences.     

Quantitative biogeography in the South America highlands—recognizing the Altoandina, Puna and Prepuna through the study of Poaceae

The distribution data of 340 grass species sampled in a region of 53.219 km² in the northwestern corner of Argentina (between ∼21°S and ∼24°S) were analyzed to search for concordance in species distributions by using the program NDM/VNDM. Here, the traditional biogeographic hypothesis proposed for the region is evaluated for the first time by using a quantitative method and an optimal criterion specifically developed within the context of areas of endemism. Three different grid sizes (0.5° × 0.5°, 0.35° × 0.35 ° and 0.2° × 0.2°) were used to analyze three nested data sets: species found in the Andes of Argentina, Bolivia and/or Chile; Andean distributed species; and all grass species found in the study region. The main areas supported by the analyses correspond generally to the traditional biogeographic hypothesis proposed for the region. Local distribution patterns defined by species restricted to the study region were best supported under the small grid sizes, while the bigger grid sizes recovered areas defined by species with a broader distribution. The local distribution patterns emerged in all the analyses even when widespread species were added to the data set.
 © The Willi Hennig Society 2009.     

Phytoextraction of salts by Atriplex Nummularia Lindl. irrigated with reject brine under varying water availability

Abstract

Reverse osmosis is a widely known technology used to produce fresh water from brackish waters. However, the reject brine from desalination plants poses a serious threat to the environment due to soil and groundwater salinization. The aim of this study was to investigate the potential of Atriplex nummularia to extract salts from a soil irrigated with reverse osmosis brine, at varying moisture levels. A field experiment was conducted in a split-plot design, with randomized complete blocks replicated four times. Treatments consisted of irrigation with reject brine in the main plots, with four relative percentages of the soil moisture at field capacity (100, 85, 70, and 50%), and two levels of organic fertilization in the subplots (0 and 1.5?L plant^?1 of goat manure). The mineral composition of leaves and stems indicated that the highest salt extraction by plants occurred when soil moisture was maintained at 100% field capacity. The salt extraction capacity of A. nummularia indicates a high potential for phytoremediation of soils affected by brine disposal from reverse osmosis plants.     

Peripheral diabetic neuropathy and polyunsaturated fatty acid supplementations: natural sources or biotechnological needs?

The two essential fatty acids linoleic and alpha-linolenic acids, precursors of the n-6 and n-3 PUFA family, respectively, are known to play a strong regulatory function on cells via their incorporation into membrane phospholipids, and also on microcirculation by the production of eicosanoids. Moreover, diabetes mellitus induces impairment in PUFA metabolism due to an inhibition of desaturases, the enzymes involved in their synthesis. The decrease in PUFA bioavailability will conduct to marked alterations in membranes as well as impairment of the microcirculation. Those metabolic perturbations are involved in part in the degenerative complications of diabetes such as neuropathy. Nutritional supplementations with PUFA have given very interesting results in experimental diabetic neuropathy but also in human diabetic neuropathy. The gamma linolenic and arachidonic acids, members of the n-6 family, prevent the physiological abnormalities associated to neuropathy. The results obtained with the n-3 family PUFA are more discordant, probably because of the simultaneous use of eicosapentaenoic and docosahexaenoic acids. Nevertheless, the use of docosahexaenoic acid-enriched phospholipids produced positive results in the treatment of experimental diabetic neuropathy. These PUFA are available from natural sources but a biotechnological demand exists to provide these PUFA in different structural forms.     

Observations on the critical micellar concentration of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine and a series of its homologs and analogs

In a study designed to explore the physical chemical characteristics of platelet activating factor (PAF), or 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, the critical micellar concentration of this compound, as well as the propionyl, butyryl and hexanoyl homologs was determined. In addition, an analogous series of compounds, in which the 1-O-alkyl was replaced by a 1-O-hexadecanoyl or a 1-O-octadecanoyl group, were examined for their critical micellar concentration. A variety of analytical techniques including NMR, gas liquid chromatography, infra-red spectrometry, thin layer chromatography, phosphorus, choline, glyceryl ether and fatty acid analyses were used to confirm the high purity of the individual derivatives. A dye binding assay and a surface tension technique were compared as to their suitability for determination of the critical micellar concentration of these compounds. Whereas the dye binding method proved highly variable, the surface tension procedure proved to be a facile, reproducible technique and was the assay of choice. The critical micellar concentration of the 1-O-alkyl and the 1-O-acyl derivatives showed comparable values for each short chain substituent at carbon 2, with values, in microM, ranging from 1.3 +/- 0.03 for 1-O-hexadecanoyl-2-acetyl-sn-glycero-3-phosphocholine and 1.1 +/- 0.10 for 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine to 0.22 +/- 0.01 for 1-O-hexadecanoyl-2-hexanoyl-sn-glycero-3-phosphocholine and 0.18 +/- 0.03 for 1-O-hexadecyl-2-hexanoyl-sn-glycero-3-phosphocholine. The data show that at the molar concentration usually employed in biological studies with these compounds, i.e., 1 X 10(-7) to 10(-11) M, one can assume that they will be present as monomolecular species. Thus, it seems unlikely that the widely diverse biological activities of these compounds can be explained by this physical parameter.     

Inferring nocturnal surface fluxes from vertical profiles of scalars in an Amazon pasture

Ecosystem carbon budgets depend on there being good representative surface flux observations for all land use types during the entire diurnal cycle. In calm conditions that often occur at night, especially in areas of small roughness (such as pastures), ecosystem respiration rate is poorly measured using the eddy covariance (EC) technique. Nocturnal vertical profiles of temperature, humidity and winds were observed using tethered balloon soundings in a pasture in the eastern Amazon during two campaigns in 2001. The site is characterized by very weak winds at night, so that there is insufficient turbulence for the EC technique to determine fluxes accurately. To compensate, the time evolution of the profiles is used to determine surface fluxes at early morning and these are compared with those observed by EC at a nearby micrometeorological tower. The nocturnal boundary layer thickness h is determined as the height to which the surface fluxes must converge so that energy budget closure is achieved. The estimated values range from 30 m, around 22:00 hours LST, to more than 100 m just before dawn. These are in good agreement with the observed thickness of a frequently observed fog layer during the middle of the night. During the early portion of the night, when the accumulation layer is shallow, there is appreciable decrease of dCO₂/dt with height. On calm nights, CO₂ accumulation rate is larger near the surface than at higher levels. On windier nights, this accumulation rate is vertically uniform. Hence, extrapolation of tower profiles for estimating fluxes must be done carefully. Although uncertainties remain large, an alternate approach to the EC method is described for measuring nighttime surface CO₂ fluxes under stable atmospheric conditions.     

Metformin inhibition of colorectal cancer cell migration is associated with rebuilt adherens junctions and FAK downregulation

E-cadherin, a central component of the adherens junction (AJ), is a single-pass transmembrane protein that mediates cell–cell adhesion. The loss of E-cadherin surface expression, and therefore cell–cell adhesion, leads to increased cell migration and invasion. Treatment of colorectal cancer (CRC)-derived cells (SW-480 and HT-29) with 2.0 mM metformin promoted a redistribution of cytosolic E-cadherin to de novo formed puncta along the length of the contacting membranes of these cells. Metformin also promoted translocation from the cytosol to the plasma membrane of p120-catenin, another core component of the AJs. Furthermore, E-cadherin and p120-catenin colocalized with β-catenin at cell–cell contacts. Western blot analysis of lysates of CRC-derived cells revealed a substantial metformin-induced increase in the level of p120-catenin as well as E-cadherin phosphorylation on Ser^838/840, a modification associated with β-catenin/E-cadherin interaction. These modifications in E-cadherin, p120-catenin and β-catenin localization suggest that metformin induces rebuilding of AJs in CRC-derived cells. Those modifications were accompanied by the inhibition of focal adhesion kinase (FAK), as revealed by a significant decrease in the phosphorylation of FAK at Tyr³⁹⁷ and paxillin at Tyr¹¹⁸. These changes were associated with a reduction in the numbers, but an increase in the size, of focal adhesions and by the inhibition of cell migration. Overall, these observations indicate that metformin targets multiple pathways associated with CRC development and progression.     

Removal of Ca(II) and Mg(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse grafted with EDTA dianhydride (EDTAD)

In a previous work, chemically modified cellulose (EMC) and sugarcane bagasse (EMMB) were prepared from mercerized cellulose (MC) and twice-mercerized sugarcane bagasse (MMB) using ethylenediaminetetraacetic dianhydride (EDTAD) as modifying agent. In this work we described in detail the modification of these materials in function of reaction time and EDTAD amount in the reaction media. The resistance of ester bond at pH 1, 2, 11, and 12 was also evaluated by FTIR. The results were used to model the hydrolysis process and a kinetic model was proposed. The modified materials (EMMB and EMC) were used to adsorb Ca²⁺ and Mg²⁺ ions from aqueous single solutions. The adsorption isotherms were developed at two pH values. These materials showed maximum adsorption capacities for Ca²⁺ and Mg²⁺ ions ranging from 15.6 to 54.1 mg/g and 13.5 to 42.6 mg/g, respectively. The modified material from sugarcane bagasse (EMMB) showed larger maximum adsorption capacities than modified material from cellulose (EMC) for both metals.