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排序方式: 共有159条查询结果,搜索用时 31 毫秒
81.
Jennessen J Nielsen KF Houbraken J Lyhne EK Schnürer J Frisvad JC Samson RA 《Journal of agricultural and food chemistry》2005,53(5):1833-1840
Fast-growing Zygomycetes, most notably Rhizopus oligosporus, are traditionally used in many food fermentations, for example, for soybean tempeh production. R. oligosporus is considered to belong to the Rhizopus microsporus group. Certain R. microsporus strains have been reported to produce either the pharmaceutically active rhizoxins or the highly toxic rhizonins A and B. In this study was investigated the formation of secondary metabolites by R. microsporus, R. oligosporus, and Rhizopus chinensis grown on a wide range of different semisynthetic and natural substrates. Liquid chromatography, combined with photodiode array detection and high-resolution mass spectrometric techniques, was used to identify secondary metabolites. Growth on maize, brown rice, and Pharma agar gave both the highest amounts and the maximum diversity of rhizoxins and rhizonins. Rhizoxins were produced by all four R. microsporus strains, whereas only one strain produced rhizonins. The six R. oligosporus and four R. chinensis strains investigated did not produce any of these two classes of metabolites. 相似文献
82.
Susanne Meier Regine Kunzmann Friedrich J. Zeller 《Genetic Resources and Crop Evolution》1996,43(1):91-96
Summary The accurate identification and classification of wild species enhance the utilization of potential plant genetic resources. The wild rye species Secale vavilovii Grossh. may serve to broaden the genetic variation in cultivated rye, S. cereale. The combined analyses of cytological, isozymic and other genetic characteristics in the present study revealed that of the fourteen rye accessions designated as S. vavilovii, only three accessions were correctly classified. Thus it is essential to increase multidisciplinary, international research and collaboration to aid in the classification and utilization of the yet untapped plant germplasm. 相似文献
83.
Dietrich Werner Regine Berggold Dieter Jaeger Arno Krotzky Hans Papen Sigrid Schenk Heidemarie Thierfelder 《植物养料与土壤学杂志》1989,152(2):231-236
A genotype effect on associative (rhizosphere) N2-fixation was observed with two cultivars of Sorghum bicolor (nutans) with a maximum rate of 8 μmol C2H4 · h?1 · plant?1 in one genotype compared to 0.9 μmol in the other. Characteristics of the high fixing genotype were a reduced transpiration rate, a lower number of stomata and increased root exudate production per gram root dry weight with higher concentration of dicarboxylic acids. The bacterial rhizosphere composition revealed a three times higher number of N2-fixing bacteria, a tenfold reduction of actinomycetes and a threefold reduction of Arthrobacter associated with the high fixing cultivar compared to the low fixing genotype. From these and other plant rhizospheres two new nitrogen fixing bacteria, Pseudomonas stutzeri and Erwinia herbicola, were characterized. With the N2-fixing bacteria Azospirillum brasilense and Klebsiella pneumoniae an enhancement of specific nitrogenase activity by aromatic compounds, for example phenolics, the herbicide alachlor and the insecticide carbofuran was demonstrated. An oscillating nitrogenase activity in Azospirillum brasilense under microaerobic conditions was found, resulting from an encystation and deencystation under those conditions. Experiments with wheat roots demonstrated that reduced oxygen tensions, essential for a maximum rhizosphere N2-fixation, reduced root growth significantly and altered the N-metabolism of the roots. 相似文献
84.
Aim, Scope and Background Hexyl is along with TNT a possible pollutant of ammunition contaminated soils. To assess the ecological risk of a pollutant
biotests are obligatory to gain information of the effects on the habitat function of the contaminated soil. The effect of
Hexyl was investigated using the standardised biotests for the springtailFolsomia Candida and the enchytraeidEnchytraeus crypticus.
Method The tests with Hexyl were performed in spiked standard soil (Lufa 2.2). The toxic endpoints were mortality (short-term test,
exposure time 7 days) and reproduction rate (long-term test, exposure time 28 days). The effect on the reproduction was further
investigated by transferring animals from contaminated soil material onto uncontaminated substrate. Then the number of offspring
was determined for the collembola and the cocoon- and hatching rates for the enchytraeid. Results. The mortality of the collembola
was not influenced by Hexyl, but the number of offspring was significantly reduced. On the bases of these data the influence
of the contaminant on the fertility of the adults itself was investigated. Therefore a reproduction test was performed with
adult springtails transferred from contaminated onto uncontaminated soil material. It was shown that the fertility of the
adults was not affected by Hexyl indicating a strong lethal effect on the juveniles. In case of the enchytraeid the mortality
as well as the reproduction was affected. The surviving enchytraeids turned yellow and rigid in the mortality tests. They
were also reduced in size compared to individuals in the uncontaminated control soil material. Thus the cocoon and hatching
rates of worms transferred from contaminated soil material onto agar-agar was further investigated. Indeed, the reproduction
(both cocoon production and juvenile hatching) was affected by the contaminant. However, the effect was not as strong as might
have been suggested by their change in colour and size. A rapid recovery of the worms was observed, too.
Conclusion Hexyl is toxic for the two terrestrial invertebrates, although in comparison to other explosives tested it is less toxic than
TNT, but more toxic than the other explosives such as Hexogen (RDX) and Octogen (HMX) or TAT, the end product of the microbial
reduction of TNT. So far, all these substances have only been tested with the luminescent bacteriaVibrio fischeri, for which Hexyl and TNT were classified as very toxic to aquatic organisms. With earthworms (Eisenia fetida andEisenia andrei) only TNT, Hexogen and Octogen have been investigated. TNT was also the most toxic of these substances.
Outook Hexyl is one of the main pollutants of ammunition-contaminated sites and has to be considered as a toxic compound. Therefore
an assessment of its full ecological impact is necessary and should include tests with animals from different trophic levels
as well as biotests with plants and microorganisms. 相似文献
85.
Obied HK Allen MS Bedgood DR Prenzler PD Robards K Stockmann R 《Journal of agricultural and food chemistry》2005,53(4):823-837
Biophenols have attracted increasing attention during the past few years due to their biological activities and natural abundance and are potential targets for the food and pharmaceutical industries. Olive mill waste (OMW) is rich in biophenols and typically contains 98% of the total phenols in the olive fruit, making value addition to OMW an attractive enterprise. The phenolic profile of OMW is complex, yet this complexity has not been fully exploited in the valorization of the waste. Most work on the bioactivity of OMW has focused on antioxidant and antimicrobial activities. The analytical techniques used to identify and quantify active biophenols are also reviewed. 相似文献
86.
Arginine vasopressin as a thyrotropin-releasing hormone 总被引:4,自引:0,他引:4
Although hypothyroidism (with concomitant increased levels of thyroid-stimulating hormone) has been associated with elevated plasma vasopressin, the role that vasopressin plays in controlling thyroid-stimulating hormone secretion from the adenohypophysis is not understood. In two in vitro pituitary cell systems, vasopressin caused a specific and dose-related release of thyroid-stimulating hormone from cells that was equal in potency to that elicited by thyrotropin-releasing hormone, the primary acknowledged regulator of thyroid-stimulating hormone release. When injected into the hypothalamus, however, vasopressin specifically inhibited the release of thyroid-stimulating hormone. Thus, vasopressin may exert differential regulatory effects on thyroid-stimulating hormone secretion in the hypothalamus and pituitary gland. 相似文献
87.
Fluorescence imaging was utilized to demonstrate the potential of blue-green fluorescence (BGF) and chlorophyll-a fluorescence (ChlF) to discriminate nitrogen (N), phosphorus (P), and potassium (K) deficiencies in sunflower plant showing similar growth inhibition. Only K-deficient leaves displayed significant increase of the BGF intensity. The epidermal UV-transmittance estimated by the ratio of ChlF intensities induced by UV and blue excitations (ChlFUV/ChlFBLUE) markedly decreased in both N- and P-deficient leaves but only in the latter that we observed significant decrease of the ratio of red and far-red ChlF intensities (RF/FRF) (that is inversely related to leaf chlorophyll concentration). The BGF increase in K-deficient was limited at leaf apex and margins and was spatially correlated to localized RF/FRF increases. Images analysis allows a better interpretation of the fluorescence changes by showing the spatial relationships between BGF, the ChlFUV/ChlFBLUE and the RF/FRF ratios that are indicative of physiological disturbances occurring in leaves of nutrient deficient plants. 相似文献
88.
J. L. Whitworth R. G. Samson T. C. Allen A. R. Mosley 《American Journal of Potato Research》1993,70(6):497-503
Greenhouse-grown Russet Burbank and Russet Norkotah plants were tested for potato leafroll virus (PLRV) by visual examination, enzyme-linked immunosorbent assay (ELISA) and direct tissue-blotting assay (DTBA). Visibly infected and healthy plants were obtained from excised eyes of tubers submitted for winter certification tests. Each plant was sectioned into leaf, petiole, stem, root, seed piece, and tuber portions. Tissues were blotted on a nitrocellulose membrane for DTBA and then homogenized for use in a double-antibody sandwich ELISA system. Agreement between the two serological detection methods and with visual readings was high for petioles and stems, but lower for leaf, tuber and root tissues. Comparison of DTBA with ELISA and with visual plant symptoms suggest that DTBA can be used with the same accuracy as ELISA for detecting PLRV in stems and petioles 相似文献
89.
Schoenlechner R Drausinger J Ottenschlaeger V Jurackova K Berghofer E 《Plant foods for human nutrition (Dordrecht, Netherlands)》2010,65(4):339-349
The use of amaranth, quinoa and buckwheat for the production of gluten-free pasta was investigated in the present study. The
aim of the work was to produce pasta of good textural quality, in particular, low cooking loss, optimal cooking weight and
texture firmness. The results demonstrated that pasta produced from amaranth had decreased texture firmness and cooking time,
while pasta from quinoa mainly showed increased cooking loss. In buckwheat pasta the least negative effects were observed.
By combination of all three raw materials to one flour blend in the ratio of 60% buckwheat, 20% amaranth and 20% quinoa, dough
matrix was improved. After decreasing dough moisture to 30%, addition of an increased amount of egg white powder of 6% and
addition of 1.2% emulsifier (distilled monoglycerides) texture firmness as well as cooking quality of gluten-free pasta produced
from such a flour blend reached acceptable values comparable to wheat pasta. 相似文献
90.
Mariana S.L. Ferreira Pierre Martre Cécile Mangavel Christine Girousse Natalia N. Rosa Marie-Françoise Samson Marie-Hélène Morel 《Journal of Cereal Science》2012
Durum wheat is grown in the Mediterranean area where drought and high temperature frequently prevail and impact grain texture, composition and yield. The purpose of this work was to examine the effect of high temperature on grain development and final composition according to the timing of exposure. High temperature (up to 27.5 °C) was applied either during the linear grain filling or drying phases or during whole grain development. The dynamics of grain dry mass, water, glutenin polymers, and protein bodies during grain development were determined. Irrespective of high temperature timing, the arrest of grain filling was observed at 45.9% grain moisture content. At that point, starch granules included in endosperm cells reached their physical packing limit, limiting further deposits. HT applied before physiological maturity shortened the duration of grain filling and resulted in a significant increase in grain protein concentration and in the proportion of vitreous grain. Late formation of sodium dodecyl sulfate (SDS)-insoluble glutenin polymers below 32% grain moisture content was also favored. The ability of wheat storage protein to form a viscoelastic matrix embedding starch granules at the beginning of grain desiccation is proposed to be mandatory for gaining vitreous grains and a high proportion of SDS-insoluble glutenin polymers. 相似文献