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991.
992.
Marchioni E Horvatovich P Charon H Kuntz F 《Journal of agricultural and food chemistry》2005,53(10):3769-3773
Protocol EN 1786 for the detection of irradiated food by electron spin resonance (ESR) spectroscopy was not conceived for the detection of irradiated bone-containing ingredients included in low concentration in non-irradiated food. An enzymatic hydrolysis method, realized at 55 degrees C, has been developed for the extraction of the bone fraction. When followed by a purification of the extracts by an aqueous solution of sodium polytungstate, this method made possible the detection of irradiated mechanically recovered poultry meat at very low inclusions (0.5%, wt/wt by ESR) in various meals (quenelles and precooked meals). 相似文献
993.
Black cohosh acts as a mixed competitive ligand and partial agonist of the serotonin receptor 总被引:6,自引:0,他引:6
Burdette JE Liu J Chen SN Fabricant DS Piersen CE Barker EL Pezzuto JM Mesecar A Van Breemen RB Farnsworth NR Bolton JL 《Journal of agricultural and food chemistry》2003,51(19):5661-5670
Extracts of the rhizome of black cohosh [Actaea racemosa L., formerly called Cimicifuga racemosa (L.) Nutt.] were evaluated for potential mechanisms of action in the alleviation of menopausal hot flashes. Ovariectomized Sprague-Dawley rats were administered a 40% 2-propanol extract of black cohosh [4, 40, and 400 mg/(kg.day)] by gavage for 2 weeks with or without estradiol [50 microg/(kg.day)] to determine if black cohosh could act as an estrogen or antiestrogen on the basis of an increase in uterine weight or vaginal cellular cornification. No effects were observed on uterine weight or on vaginal cellular cornification in rats treated with black cohosh alone or in combination with 17beta-estradiol, indicating this black cohosh extract had no estrogenic or antiestrogenic properties in the ovariectomized rat model. To evaluate other potential pathways by which black cohosh might reduce menopausal hot flashes, serotonin activity was first assessed by the inhibition of radioligand binding to cell membrane preparations containing recombinant human serotonin receptor (5-HT) subtypes. A 40% 2-propanol extract of black cohosh was tested against 10 subtypes of the serotonin receptor, revealing the presence of compounds with strong binding to the 5-HT(1A), 5-HT(1D), and 5-HT(7) subtypes. Subsequent binding studies were carried out using 5-HT(1A) and 5-HT(7) receptors because of their association with the hypothalamus, which has been implicated in the generation of hot flashes. The black cohosh 40% 2-propanol extract inhibited [(3)H]lysergic acid diethylamide (LSD) binding to the human 5-HT(7) receptor (IC(50) = 2.4 +/- 0.4 microg/mL) with greater potency than binding of [(3)H]-8-hydroxy-2-(di-N-propylamino)tetralin to the rat 5-HT(1A) receptor (IC(50) = 13.9 +/- 0.6 microg/mL). Analysis of ligand binding data indicated that components of a black cohosh methanol extract functioned as a mixed competitive ligand of the 5-HT(7) receptor. In addition, a black cohosh methanol extract elevated cAMP levels in 293T-5-HT(7)-transfected HEK cells, suggesting the extract acted as a partial agonist at the receptor. The elevation in cAMP mediated by the black cohosh extract could be reversed in the presence of the antagonist methiothepin, indicating a receptor-mediated process. These data suggest that reductions in hot flashes in some women taking black cohosh may not be due to estrogenic properties. This study identifies other possible biological targets of black cohosh that could account for reported biological effects. 相似文献
994.
Ruibal-Mendieta NL Delacroix DL Mignolet E Pycke JM Marques C Rozenberg R Petitjean G Habib-Jiwan JL Meurens M Quetin-Leclercq J Delzenne NM Larondelle Y 《Journal of agricultural and food chemistry》2005,53(7):2751-2759
The nutritional value of breadmaking cereal spelt (Triticum aestivum ssp. spelta) is said to be higher than that of common wheat (Triticum aestivum ssp. vulgare), but this traditional view is not substantiated by scientific evidence. In an attempt to clarify this issue, wholemeal and milling fractions (sieved flour, fine bran, and coarse bran) from nine dehulled spelt and five soft winter wheat samples were compared with regard to their lipid, fatty acid, and mineral contents. In addition, tocopherol (a biochemical marker of germ) was measured in all wholemeals, whereas phytic acid and phosphorus levels were determined in fine bran and coarse bran samples after 1 month of storage. Results showed that, on average, spelt wholemeals and milling fractions were higher in lipids and unsaturated fatty acids as compared to wheat, whereas tocopherol content was lower in spelt, suggesting that the higher lipid content of spelt may not be related to a higher germ proportion. Although milling fractionation produced similar proportions of flour and brans in spelt and wheat, it was found that ash, copper, iron, zinc, magnesium, and phosphorus contents were higher in spelt samples, especially in aleurone-rich fine bran and in coarse bran. Even though phosphorus content was higher in spelt than in wheat brans, phytic acid content showed the opposite trend and was 40% lower in spelt versus wheat fine bran, which may suggest that spelt has either a higher endogenous phytase activity or a lower phytic acid content than wheat. The results of this study give important indications on the real nutritional value of spelt compared to wheat. Moreover, they show that the Ca/Fe ratio, combined with that of oleate/palmitate, provides a highly discriminating tool to authenticate spelt from wheat flours and to face the growing issue of spelt flour adulteration. Finally, they suggest that aleurone differences, the nature of which still needs to be investigated, may account for the differential nutrient composition of spelt and wheat. 相似文献
995.
Timothy V. Larson Robert J. Charlson Eric J. Knudson Gary D. Christian Halstead Harrison 《Water, air, and soil pollution》1975,4(3-4):319-328
Sampling and chemical analysis of a rainstorm were undertaken to determine the influence of a large source of SO2 on regional precipitation chemistry. A definite correlation was obtained between hydrogen ion, sulfate ion and As concentration increases downwind of the source. Estimated sulfate deposition in a 1500 km2 downwind area was compared to existing models. 相似文献
996.
Elizabeth A. S. Rattray Eric Paterson Kenneth Killham 《Biology and Fertility of Soils》1995,19(4):280-286
The dynamics of C partitioning with Lolium perenne and its associated rhizosphere was investigated in plant-soil microcosms using 14C pulse-chase labelling. The 14CO2 pulse was introduced into the shoot chamber and the plants allowed to assimilate the label for a fixed period. The microcosm design facilitated independent monitoring of shoot and root/soil respiration during the chase period. Partitioning between above- and below-ground pools was determined between 30 min and 168 h after the pulse, and the distribution was found to vary with the length of the chase period. Initially (30 min after the pulse), the 14C was predominantly (99%) in the shoot biomass and declined thereafter. The results indicate that translocation of recent photoassimilate is rapid, with 14C detected below ground within 30 min of pulse application. The translocation rate of 14C below ground was maximal (6.2% h-1) between 30 min and 3 h after the pulse, with greatest incorporation into the microbial biomass detected at 3 h. After 3 h, the microbial biomass 14C pool accounted for 74% of the total 14C rhizosphere pool. By 24 h, approximately 30% of 14C assimilate had been translocated below ground; thereafter 14C translocation was greatly reduced. Partitioning of recent assimilate changed with increasing CO2 concentration. The proportion of 14C translocated below ground almost doubled from 17.76% at the ambient atmospheric CO2 concentration (450 ppm) to 33.73% at 750 ppm CO2 concentration. More specifically, these changes occurred in the root biomass and the total rhizosphere pools, with two- and threefold 14C increases at an elevated CO2 concentration compared to ambient, respectively. The pulselabelling strategy developed in this study provided sufficient sensitivity to determine perturbations in C dynamics in L. perenne, in particular rhizosphere C pools, in response to an elevated atmospheric CO2 concentration. 相似文献
997.
Mum-Keng Wong Paramananthan Selliah Meor Hakif Amir Hassan Eric Van Ranst Kazuyuki Inubushi 《Soil Science and Plant Nutrition》2020,66(1):214-224
ABSTRACT In Malaysia, soils derived from sedimentary rocks are extensively used for agricultural purposes with oil palm and rubber being the main dwellers. In order to understand the environmental impact of these perennial crops planting, the variability of physicochemical properties of 25 representative soils derived from sedimentary rocks under different ecosystems (agriculture land and natural forest) at six study sites spread across Malaysia was examined. Among the soil physicochemical properties, total soil organic carbon, total nitrogen, and fertility level were found to be generally higher in the forest ecosystems followed by rubber plantation and finally oil palm plantations. Likewise, projection of principal component analysis showed an associative relationship between soil physicochemical properties and microhabitats. Finally, this study showed that soils from different agricultural and natural sites, but derived from similar sedimentary rocks, had distinctive weathering conditions and soil properties. Therefore, site-specific field management according to soil type, soil management techniques as well as fertilizer strategies are required to maximize crop production and to sustain ecosystem services. The output of this study will enable farmers to improve their crop yield via the selection of suitable crops cultivation based on soil characteristics. 相似文献
998.
We analyze the status of the Angel de la Guarda deer mouse (Peromyscus guardia), a species endemic to Mexico, based on our own fieldwork, bibliographic records and information from colleagues. This species, with different subspecies on three islands and a population of an undetermined subspecies on a fourth, was apparently common until the mid-1960s. Currently the species is critically endangered, if not already extinct. One of the subspecies and the undetermined population are presumed extinct. Of the two other subspecies, one is at least in critical condition, and the other at least reduced. The demise of the species can be attributed to the introduction of domestic cats. The case of P. guardia is a good example of the vulnerability of other taxa of endemic rodents on islands in the Gulf of California. 相似文献
999.
Enhanced resistance to Helicoverpa zea in tobacco expressing an activated form of maize ribosome- inactivating protein 总被引:5,自引:0,他引:5
Dowd PF Zuo WN Gillikin JW Johnson ET Boston RS 《Journal of agricultural and food chemistry》2003,51(12):3568-3574
Progeny of two transgenic tobacco (Nicotiana tabacum L.) lines that expressed an activated form of maize (Zea mays L.) ribosome-inactivating protein (RIP) had varying resistance to the insect species tested. A subset of R(2) plants from the two lines appeared to be more resistant to larvae of the cigarette beetle, Lasioderma serricorne (F.), and the tobacco hornworm, Manduca sexta (L.) than the wild type plants. Progeny (R(3)) of the more resistant R(2) plants were tested more extensively for insect resistance. Resistance to the corn earworm, Helicoverpa zea (Boddie), was most consistent, with significantly decreased feeding often accompanied by increased mortality and reduced weights of survivors fed on leaf disks of the two transgenic lines compared to the wild type. The amount of damage by H. zea was significantly inversely correlated with levels of RIP. Resistance of RIP-producing plants to H. zea was greater than expected on the basis of prior in vitro results using diet-incorporated maize RIP. The R(3) transgenic plant leaf disks were also often more resistant to feeding by larvae of L. serricorne compared to wild type plants. Although reduced feeding by M. sexta was noted when they were fed leaf disks from transgenic compared to wild type plants the first day of exposure, differences were not significant. This information provides further support for maize RIP having a role in resistance to maize-feeding insects. 相似文献
1000.
Eric S. Menges Pedro F. Quintana Ascencio Orou G. Gaoue 《Biological conservation》2006,127(1):115-127
We use population viability analysis of an endangered Florida scrub mint, Dicerandra frutescens, to specify the optimal fire return intervals for its long-term persistence and for its specific habitat. We derived 83 population projection matrices from 13 years of demographic data from eight populations, 59 matrices from scrub populations and 24 from firelane or yard edges. Seed dormancy and germination transitions were inferred based on experimental data and verified by comparing modeled vs. observed population trajectories. Finite rates of increase in scrub sites were highest shortly after fire and declined steeply through 10 years postfire. The break-even value of λ = 1 was passed quickly, in about six years, suggesting that populations >6 years postfire were already facing decline. The decline is probably related to the rapid growth of competing shrubs in the habitat of D. frutescens. In long-unburned sites, finite rates of increase were nearly always <1 and declined the most in the long-unburned site with no foot trails or treefall gaps. Finite rates of increase in firelane populations also declined with years since fire or last disking. The yard edge population showed λ values both >1 and <1, with no temporal trend. Stochastic simulations in scrub sites suggested an optimal regular fire return interval of about 6-12 years. Regular fires at this interval were more favorable than stochastic fire regimes, but stochasticity reduced extinction percentages at longer fire return intervals. Stochastic fire return intervals implied a wider optimal fire return interval of 6-21 years. We suggest that prescribed fire in Florida scrub on yellow sand has occurred (and needs to occur) more frequently than previously recommended. 相似文献