Chromium Phytoaccumulation from Solution by Selected Hydrophytes

There is increasing interest in the role of wetland plants in the aquatic phytoremediation of toxic metals. In this experiment, we evaluate the Cr removal capacity of four hydrophyte species (Nasturtium officinale L., Veronica beccabunga L., Mentha longifolia L., R.Br., Cardamine uliginosa L.) under varying nutritional conditions (full-strength and half-strength solution cultures), and over a range of Cr concentration (0, 2, 4, 6, and 8 mg L^-1). The results indicate that Cr accumulation is affected by both initial Cr concentration and strength of the nutrient solution. Phytoaccumulation increased with initial Cr concentration and plants grown in the full-strength solution accumulated more Cr at the higher initial solution concentration. Cr was predominantly accumulated in the roots, with minimal shoot translocation, which limits the hazard of Cr entering the food chain through ingestion by animals. Accumulation was large and reached up to 6700 mg Cr Kg^-1 in the roots of Veronica beccabunga.     

Laboratory studies on the biology of the corn leaf aphid, Rhopalosiphum maidis (Homoptera: Aphididae)

The biology of R. maidis has been shown to be affected considerably by the temperature, the host plant, and the physiological age of food plant. The optimum temperature was 30°C; here nymphal development was accelerated, the whole life-span was drastically shortened to less than half that at 15°, and natality rate/surviving female was increased with rather negligible deaths among progeny. Barley was the most favourable host studied under the specified experimental conditions, and young plants (3–5 days old) represented the best stage of plant growth. R. maidis may have about 50 generations/year when aphids were kept feeding continuously on 5-day old barley plants but this does, by no means, represent the actual number of generations under field conditions; it only indicates that almost half of these may be restricted to the summertime.

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Résumé La présente étude montre que la température, ainsi que l'espèce de la plante hôte et son âge physiologique influencent grandement la biologie de Rhopalosiphum maïdis.Quand ce puceron est élevé sur des pousses d'orge âgées de 5 jours, la température optimum est de 30°. Dans ces conditions, la maturation peut être acquise en un délai aussi court que 4,6 jours, tandis que la longévité est réduite à 16,8±1,3 jours contre 35,1±5,1 jours à 15°. Enfin, la natalité par femelle et par jour est accrue avec un taux de mortalité négligeable parmi la descendance.De quatre plantes testées, (orge, mil, fève et maïs) au même âge de croissance (7 jours) l'orge est le plus favorable. Rhopalosiphum maïdis peut avoir environ 50 générations par an quand il est élevé de façon continue sur des plants d'orge âgés de 5 jours; cela ne signifie pas que dans les conditions naturelles il en est ainsi, mais indique que presque la moitié de ce nombre de générations peut intervenir pendant l'été.

     

Hair Trace Elements Concentration to Describe Polymetallic Mining Waste Exposure in Bolivian Altiplano

Severe polymetallic contamination is frequently observed in the mining communities of Bolivian Altiplano. We evaluated hair trace elements concentrations at the population level to characterise exposure profile in different contexts of contact with mining and metallurgical pollution. We sampled 242 children aged 7 to 12 years in schools from five Oruro districts located in different contexts of potential contamination. Hair trace elements concentrations were measured using ICP-MS (Pb, As, Hg, Cd, Sb, Sn, Bi, Ag, Ni, Se, Cu, Cr, Mn, Co and Zn). We compared concentration according to school areas and gender. Concentrations were markedly different depending on school areas. Children from schools near industrial areas were far more exposed to non essential elements than children from downtown and suburban schools, as well as the rural school. The most concentrated non-essential element was Pb (geometric means (SD): 1.6 (1.3) μg/g in rural school; 2.0 (2.3) μg/g in suburban school; 2.3 (3.0) μg/g in downtown school; 14.1 (2.7) μg/g in the mine school and 21.2 (3.3) μg/g in the smelter school). Boys showed higher levels for all non-essential elements while girls had higher levels of Zn. Hair trace elements concentrations highlighted the heterogeneity of exposure profiles, identifying the most contaminated districts.     

Engineering the Virtual Enterprise: An Architecture-Driven Modeling Approach

The managerial and organization practices required by an increasingly dynamic competitive manufacturing, business, and industrial environment include the formation of “virtual enterprises.” A major concern in the management of virtual enterprises is the integration and coordination of business processes contributed by partner enterprises. The traditional methods of process modeling currently used for the design of business processes do not fully support the needs of the virtual enterprise. The design of these virtual enterprises imposes requirements that make it more complex than conventional intraorganizational business process design. This paper first describes an architecture that assists in the design of the virtual enterprise. Then it discusses business process reengineering (BPR) as a methodology for modeling and designing virtual organizations. While BPR presents many useful tools, the approach itself and the modeling tools commonly used for redesign have fundamental shortcomings when dealing with the virtual enterprise. However, several innovative modeling approaches provide promise for this problem. The paper discusses some of these innovative modeling approaches, such as object-oriented modeling of business processes, agent modeling of organizational players, and the use of ontological modeling to capture and manipulate knowledge about the players and processes. The paper concludes with a conceptual modeling methodology that combines these approaches under the enterprise architecture for the design of virtual enterprises.     

NTPDase and 5′ ecto-nucleotidase expression profiles and the pattern of extracellular ATP metabolism in the Walker 256 tumor

In this study, we evaluated the NTPDases and ecto-5′-nucleotidase (CD73) expression profiles and the pattern of adenine nucleotide hydrolysis in rats submitted to the Walker 256 tumor model, 6, 10 and 15 days after the subcutaneous inoculation. Using RT-PCR analysis, we identified mRNA for all of the members of the ecto-nucleoside triphosphate diphosphohydrolase family investigated and a 5′-nucleotidase. By quantitative real-time PCR, Entpd1 (Cd39) and Entpd2 (Cd39L1) and CD73 were identified as the dominant genes expressed by the Walker 256 tumor, at all times studied. Extracellular adenine nucleotide hydrolysis by the Walker 256 tumor was estimated by HPLC analysis. Rapid hydrolysis of extracellular ATP by the tumor cells was observed, leading to the formation of adenosine and inosine in cells obtained from solid tumors at 6 and 10 days after inoculation. Cells obtained from solid tumors at 15 days of growth presented high levels of AMP and presented adenosine as a final product after 90 min of incubation. Results demonstrate that the presence of NTPDases and 5′-nucleotidase enzymes in Walker 256 tumor cells may be important for regulation of the extracellular adenine nucleotides/adenine nucleoside ratio, therefore leading to tumor growth.     

Anti-thromboxane activity in Rhodnius prolixus salivary secretion

The salivary secretion of Rhodnius prolixus inhibits arachidonic acid-induced platelet aggregation and the accompanying rabbit aorta-contracting activity. Results are presented that show antagonism to thromboxane A₂ on both platelet aggregation and rabbit aorta preparations. The antagonist is heat stable, non degradable by pronase, non dialysable and is sensitive to periodate oxidation.A brief review of the pharmacological properties of Rhodnius saliva is presented. It is suggested that Rhodnius prolixus developed salivary anti-haemostatic components that allows them to take a large meal in a short time.