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Understanding the microbiological, biochemical and physiological aspects of phytoremediation of soil and water environments polluted to different degrees with heavy metals has very important theoretical and practical implications. In this study, a comparison was made between total cadmium concentration in root and shoot tissues as well as concentrations of particular fractions of Cd immobilized by roots of Festuca ovina (Sheep’s fescue) hydroponically cultivated in nutrient solutions supplemented with 1 μg Cd ml⁻¹ and those cultivated at 10 μg Cd ml⁻¹. After three weeks of F. ovina cultivation, the number of bacterial CFU and the amounts of organic chelators, siderophores, proteins and reducing sugars in the growth medium and on the root surface were higher at 10 than at 1 μg Cd ml⁻¹. The grass also reacted to the high Cd concentration by a decrease in plant growth and dehydrogenase activity in root tissues. The concentration of Cd determined in fractions bound with different strength in roots was significantly dependent on Cd concentration in the growth medium. When the plants were grown at 1 μg Cd ml⁻¹, 9% of the immobilized cadmium was loosely bound to the root surface, 20% was exchangeable adsorbed, and 28% was bound by chelation; at 10 μg Cd ml⁻¹, the respective values were 12%, 25%, and 20%. About 43% of the immobilized cadmium remained in roots after sequential extraction, and bioaccumulation factors in shoots had the same values independently of Cd concentration. At both Cd concentrations, the cadmium translocation index for F. ovina was low (< 1), which is why this grass can be recommended for phytostabilization of the metal under study.
Dwa chińskie preparaty bionawożeniowe Juwei i C. B. I. uruchamiające K i P z minerałów glebowych przebadano pod względem przeżywalności zawartych w nich aktywnych mikroorganizmów podczas przechowywania i po wprowadzeniu do gleby opłaszczonych C. B. I. nasion. Po 10 miesięcznym okresie przechowywania liczebność aktywnych bakterii w Juwei obniżyła się o 1 rząd wielkości. Nie stwierdzono zmian w liczebności bakterii rozpuszczających fosforany wapnia i potasu w glebie po wprowadzeniu opłaszczonych biopreparatem nasion rzodkiewki. Liczebność bakterii uruchamiających fosfor i potas stwierdzona na jednym ziarnie kukurydzy opłaszczonym preparatem C. B. I., była 10-krotnie wyższa niż liczebność takich bakterii występująca w 1 gramie suchej gleby użytej w doświadczeniu. Badane biopreparaty były barwy czarnej, wyglądem przypominały mursz i wykazywały lekko kwaśny odczyn. Pod względem składu chemicznego biopreparat C. B. I. zawierał więcej materii organicznej, ogólnego potasu, magnezu i wapnia i mniej przyswajalnego i ogólnego fosforu niż preparat Juwei. Nie stwierdzono w nich natomiast substancji szkodliwych (metale ciężkie, pestycydy chloroorganiczne i PCB) w ilościach zagrażających funkcjonowaniu środowiska glebowego.
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Iron is a trace element involved in many cardinal metabolic processes of almost all living organisms. It is well known that iron participates in oxygen transport as well as it is a cofactor in many fundamental enzymatic and nonenzymatic processes. Accordingly, disturbances of iron homeostasis can cause serious clinical consequences. In humans, dietary iron can enter the body in two main forms: heme and nonheme. The former is a component of many hemoproteins (including myoglobin, hemoglobin, cytochromes b and c) and is easily absorbed in the duodenal enterocytes. Red meat is an excellent source of heme iron, while the less bioavailable nonheme form is found in large amounts in milk products and vegetables. For this reason, consumers of meat have a better iron status than vegetarians and vegans. The aim of this paper was to discuss the role of heme iron in the human diet. Heme iron found in muscle protein should be supplied to humans to prevent iron deficiency, which can lead to anemia. It is easily absorbed by the human body and its main source is red meat. In addition, heme iron, which is mainly found in myoglobin in meat, contributes to the desirable bright red color and to the most undesirable brown color of meat. Both heme and nonheme iron are catalysts of lipid oxidation in meat. This process lowers the nutritive value through oxidation of polyunsaturated fatty acids, which produces an undesirable flavor and aroma. The present review is focused on the role of heme iron, which is mainly found in meat and is the principal source of iron in the human diet.
Saprotrophic filamentous microfungi were isolated by means of the soil dilution method from soil samples collected from four locations in the Bellsund region of Spitsbergen (77°33'N, 14°31'E) representing the following forms of surface micro-relief: an old stormbank, a sorted circle, a frost fissure between tundra polygons, and the central part of a tundra polygon. The fungal isolates were identified and screened for their ability to grow at low temperatures. The oligotrophy of psychrophilic and psychrotrophic strains was then determined as the ability of growth on silica gel without a C source added. Differences in some physico-chemical properties were found between the soils sampled from the four sites. A total of 89 taxa from 17 genera were isolated. Most of the isolates were species of Mortierella, Penicillium, Chrysosporium and Phialophora, and half of them were psychro- philes. Fungal communities isolated from a frost fissure between tundra polygons (site 3) and from the central part of a tundra polygon (site 4) were dominated by psychrophiles but those isolated from an old stormbank (site 1) and a sorted circle (site 2) were predominantly psychrotrophic. Oligopsychrophilic taxa accounted for 27% and oligopsychrotrophic for 20% of all the isolated taxa but only from 0.7% to 11.7% and from 1.2% to 6.3% of the total number of cfu (colony forming unit) isolated from an individual site, respectively. The results of the present study suggest that the abundance of fungi in Arctic soil is mostly affected by the content of organic matter in the A horizon and the plant cover, but other factors, such as the stage of soil development and the micro-relief of the surface, are more important for species richness of fungal communities. Key words: Arctic, tundra, filamentous fungi, species richness, ecology.
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