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421.
Silicon: its manifold roles in plants 总被引:1,自引:0,他引:1
E. Epstein 《The Annals of applied biology》2009,155(2):155-160
The title of this essay declares that silicon does have roles in plants and all participants in this conference know that that is so. This knowledge, however, is not shared by the general community of plant biologists, who largely ignore the element. This baffling contrast is based on two sets of experience. First, higher plants can grow to maturity in nutrient solutions formulated without silicon. That has led to the conventional wisdom that silicon is not an essential element, or nutrient, and thus can be disregarded. Second, the world's plants do not grow in the benign environment of solution culture in plant biological research establishments. They grow in the field, under conditions that are often anything but benign. It is there, in the real world with its manifold stressful features, that the silicon status of plants can make a huge difference in their performance. The stresses that silicon alleviates range all the way from biotic, including diseases and pests, to abiotic such as gravity and metal toxicities. Silicon performs its functions in two ways: by the polymerization of silicic acid leading to the formation of solid amorphous, hydrated silica, and by being instrumental in the formation of organic defence compounds through alteration of gene expression. The silicon nutrition of plants is not only scientifically intriguing but also important in a world where more food will have to be wrung from a finite area of land, for that will put crops under stress. 相似文献
422.
G. M. Berlyne R. Shainkin-Kestenbaum R. Yagil Z. Alfassi A. Kushelevsky Z. Etzion 《Biological trace element research》1986,10(2):159-162
Carrier-free31Silicon (31Si) prepared by neutron activation, was injected in the form of31Si-labeled silicic acid into five albino male rats, and the organ and tissue distribution of labeled silicic acid was determined
at sacrifice after 30 min. The kidney was found to contain 0.85% of the injected dose (ID) per gram of tissue; skin had 0.3%
ID/G; testes 0.29; bone 0.26; liver 0.22; and brain 0.13. When expressed as % ID/organ, voluntary muscle had 14.6%; skin 10.8;
bone 3.4; liver 1.6; kidneys 1.5; testes 0.8, and brain 0.2. These results indicate the need for further research into silicon
metabolism in kidney, skin, bone, and brain. 相似文献
423.
廖宗文 《植物生理与分子生物学学报》1989,15(1):52-56
利用电子探针研究黄叶生理病的水稻根中一些元素的含量和分布,结果表明,硅和铁元素与稻叶发黄密切相关。通常稻根表皮层富集铁而内皮层富集硅,生理失调稻根表皮层中的铁远高于正常稻,而内皮层中的硅则较少。发病稻根高铁低硅的特征为深入研究发病的机理和土壤条件提供了线索。 相似文献
424.
Kelly C. Detmann Wagner L. Araújo Samuel C.V. Martins Alisdair R. Fernie Fábio M. DaMatta 《Plant signaling & behavior》2013,8(1)
Although the beneficial role of silicon (Si) in stimulating the growth and development of many plants is generally accepted, our knowledge concerning the physiological and molecular mechanisms underlying this response remains far from comprehensive. Considerable effort has been invested in understanding the role of Si on plant disease, which has led to several new and compelling hypotheses; in unstressed plants, however, Si is believed to have no molecular or metabolic effects. Recently, we have demonstrated that Si nutrition can modulate the carbon/nitrogen balance in unstressed rice plants. Our findings point to an important role of Si as a signaling metabolite able to promote amino acid remobilization. In this article we additionally discuss the agronomic significance of these novel observations and suggest Si nutrition as an important target in future attempts to improve yields of agronomic crops. 相似文献
425.
Dussadee Maneesuwannarat Sirikan Maneesuwannarat Sumol Nilratnisakorn Paitip Thiravetyan 《International journal of phytoremediation》2013,15(1):24-37
Narrow-leaved cattails (Typha angustifolia L.) show higher efficiency in the removal of colour and reduction of pH, TDS, and conductivity from synthetic reactive red dye wastewater (Rw) when silicon is added to the wastewater. The efficiency of the colour removal was increased from 86% within 12 days to 93% within 9 days with the addition of silicon. Furthermore, the TDS was also decreased when adding silicon in the wastewater. In addition, calcium and proline accumulation in the plant leaf increased in response to increasing Rw concentrations in the absence of added silicon. Higher salinity was also observed with increasing Rw concentrations. Plants attempt to balance their water potential by secreting proline as an osmotic adjustment. But both calcium and proline levels decreased when silicon was added to the wastewater. This result implies that the plant uses silicon as primary element for responsibility under salt stress condition by increasing growth of plant. In addition, silicon can be used instead of calcium, resulting in decreased proline and calcium production in the plant. 相似文献
426.
WILHELM FOISSNER BIRGIT WEISSENBACHER WOLF-DIETRICH KRAUTGARTNER URSULA LÜTZ-MEINDL 《The Journal of eukaryotic microbiology》2009,56(6):519-530
ABSTRACT. Using hydrofluoric acid, scanning electron microscope-assisted X-ray microanalysis, and energy-filtered transmission electron microscopy, we present the first definite proof of biomineralized silicon [(SiO2 )] n in a ciliophoran protist, Maryna umbrellata , a common inhabitant of ephemeral pools. In the trophic specimen, the amorphic silicon (glass) granules are accumulated in the anterior half of the body. When entering the dormant stage, most glass granules are excreted to form the surface cover of the globular resting cyst. Most likely, the silicon granules are synthesized in vesicles of the Golgi apparatus. First, nanospheres with a size of 20–40 nm are formed in a fibrous matrix; they grow to be spongious complexes, eventually becoming amorphous glass granules with an average size of 819 nm × 630 nm. In the transmission electron microscope, the silicon granules show the characteristic fracture pattern of glass known from many other silicon-bearing organisms. A literature survey suggests that silicon is very rare in ciliates. The fine structure and genesis of silicon granules in M. umbrellata are very similar to those of other organisms, including vascular plants and animals, indicating a common mechanism. Light perception and protection against mechanical stress and predators might be functions of the silicon granules in M. umbrellata . The palaeontological significance of glass cysts in ciliates is also discussed. 相似文献
427.
Effects of germanium and silicon on bone mineralization 总被引:1,自引:0,他引:1
The chemical properties of Ge are similar to Si. This study investigated whether Ge can substitute for, or is antagonistic
to, Si in bone formation. Sixty male weanling Sprague-Dawley rats were randomly assigned to treatment groups of 12 and 6 in
a 2×4 factorially arranged experiment. The independent variables were, per gram fresh diet, Si (as sodium metasilicate) at
0 or 25 μg and Ge (as sodium germanate) at 0, 5, 30 or 60 μg. Results confirmed that Ge does not enhance Si deprivation and
provided evidence that Ge apparently can replace Si in functions that influence bone composition. When Si was lacking in the
diet, calcium and magnesium concentrations of the femur were decreased; this was reversed by feeding either Ge and/or Si.
Similar effects were found for zinc, sodium, iron, manganese, and potassium of vertebra. There were some responses to Si deprivation
that Ge could not reverse: Ge did not increase femur copper, sodium, or phosphorus or decrease molybdenum of vertebra, effects
that were eveked by Si supplementation. Additionally, some findings suggested that 60 μg Ge/g diet could be a toxic intake
for the rat. On the other hand, some responses induced by Ge indicate that this element may be acting physiologically other
than as a substitute for Si. Germanium itself affected bone composition. Germanium supplementation decreased Si and molybdenum
in the femur and increased DNA in tibia. Regardless of the amount of Si fed, animals fed 30 μg Ge/g diet had increased tibial
DNA compared to animals fed 0 or 60 μg Ge; however, tibial DNA of animals fed 30 μg Ge was not statistically different from
those animals fed 5 μg Ge. Thus, Ge may be of nutritional importance. 相似文献
428.
Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model. 相似文献