Self-assembly of bovine beta-casein below the isoelectric pH     

Portnaya I  Ben-Shoshan E  Cogan U  Khalfin R  Fass D  Ramon O  Danino D 《Journal of agricultural and food chemistry》2008,56(6):2192-2198

Beta-casein is an intrinsically unstructured amphiphilic protein that self-assembles into micelles at neutral pH. This paper reports that beta-casein self-organizes into micelles also under acidic conditions. The protein association behavior and micelle characteristics at pH 2.6, well below the p I, are presented. The pH was found to strongly affect the micelle shape and dimensions. Cryogenic transmission electron microscopy (cryo-TEM) experiments revealed disk-like micelles of 20-25 nm in length and approximately 3.5 nm in height in acidic conditions. An aggregation number of 6 was determined by sedimentation equilibrium under these conditions. Isothermal titration calorimetry experiments verified the association below the p I and allowed determination of the micellization enthalpy, the critical micellar concentration, and the micellization relative cooperativity (MR). Small-angle X-ray scattering results at concentrations below the critical micellization concentration (CMC) suggest that the monomeric protein is likely in a premolten globule state at low pH. Calculations of the protein charge at acidic and neutral pH reveal a similar high net charge but considerable differences in the charge distribution along the protein backbone. Overall the results show that beta-casein is amphiphilic at low pH, but the distribution of charge along the protein chain creates packing constraints that affect the micelle organization, leading at concentrations above the CMC to the formation of disk micelles.  相似文献   

Rapid quantification of humic components in concentrated humate fertilizer solutions by FTIR spectroscopy     

Karpukhina  Evgeniya  Mikheev  Ivan  Perminova  Irina  Volkov  Dmitry  Proskurnin  Mikhail 《Journal of Soils and Sediments》2019,19(6):2729-2739

Journal of Soils and Sediments - The use of humic substances is under thorough discussion of state-of-the-art agricultural science. They are marketed mostly as concentrated aqueous solutions of...  相似文献   

The Biochemical Composition and Antioxidant Properties of Fucus vesiculosus from the Arctic Region     

Ekaterina D. Obluchinskaya  Olga N. Pozharitskaya  Denis V. Zakharov  Elena V. Flisyuk  Inna I. Terninko  Yulia E. Generalova  Irina E. Smekhova  Alexander N. Shikov 《Marine drugs》2022,20(3)

Fucus vesiculosus is one of the most prominent brown algae in the shallow waters of the seas of the Arctic region (Barents (BS), White (WS), Norwegian (NS), and Irminger (IS)). The aim of this study was to determine the biochemical composition of F. vesiculosus from the Arctic at different reproductive phases, and to evaluate the antioxidant properties of F. vesiculosus extracts. The amounts of monosaccharides, phlorotannins, flavonoids, and ash and the mineral composition significantly varied in the algae. A strong correlation was established between monosaccharide, phlorotannin, and flavonoid accumulation and water salinity (Pearson’s correlation coefficients r = −0.58, 0.83, and 0.44, respectively; p < 0.05). We noted a negative correlation between the antioxidant activity and the amount of the structural monosaccharides of fucoidan (r = −0.64). A positive correlation of phlorotannins and flavonoids with antioxidant power was confirmed for all samples. The ash accumulation was relatively lower in the sterile phase for the algae from the BS and WS. The correlation between the Metal Pollution Index (MPI) and the reproductive phases was medium with high fluctuation. Meanwhile, the MPI strongly correlated with the salinity and sampling site. The gradient of the MPI values across the sea was in the following ranking order: BS < WS < NS < IS. Taken together, and based on our data on the elemental contents of F. vesiculosus, we believe that this alga does not accumulate toxic doses of elements. Therefore, the Arctic F. vesiculosus could be safely used in food and drug development as a source of active biochemical compounds and as a source of dietary elements to cover the daily nutritional requirements of humans.  相似文献   

Detection of nonesterified (free) fatty acids in bovine serum: comparative evaluation of two methods.     

Irina Rudik Miksa  Carol L Buckley  Robert H Poppenga 《Journal of veterinary diagnostic investigation》2004,16(2):139-144

A method comparison study for the determination and quantitation of nonesterified fatty acids (NEFAs) in serum, using the commercial "NEFA C" enzymatic test kit, was performed using the spectrophotometric method recommended by the manufacturer and a modified procedure optimized for the use of a microplate reader, a 96-well microtiter plate, and small sample volumes (10 microl). Linearity, sensitivity, and precision using the test kit were determined for each method of detection. The assay was linear from 0 to 1.97 mEq/liter for both procedures, and the limits of detection were determined to be 0.22 (+/- 0.074) and 0.05 (+/- 0.002) mEq/liter for the spectrophotometer and microplate reader, respectively. Pairs of measurements for bovine serum samples were compared and evaluated by a mean difference plot method and not regression analysis, a method that has been shown to be inappropriate for method comparison studies. The difference plot was used to evaluate the systematic bias between the 2 methods. Random error is reported on the basis of SD differences, and "limits of agreement" are used to describe the maximum differences likely to occur between the 2 methods. Results suggest that the microplate reader method can be used reliably in place of the recommended spectrophotometric method. The microplate reader method is preferred because of its high throughput capabilities, simultaneous analysis of all the standards and samples, use of small sample and reagent volumes, and reduction in labor requirements and costs.  相似文献   

俄罗斯常见野生食用菌资源   总被引：1，自引：0，他引：1  

图力古尔  李玉 《中国食用菌》2008,27(3):9-13

2003年～2007年间分别在俄罗斯远东、基洛夫、新西伯利亚和阿尔泰地区进行了菌类资源调查,共采集到各类真菌标本2000余号。介绍在俄罗斯上述地区民间食用或有关文献记载食用的真菌26个科180种,为了解和借鉴该国食用菌资源提供资料。  相似文献   

Root System Distribution of Highbush Blueberry Crops of Various Ages in Medium-Textured Soils     

Cristian Paltineanu  Mihai Coman  Silvia Nicolae  Irina Ancu  Mirela Calinescu  Monica Sturzeanu  Emil Chitu  Mihaela Ciucu  Claudia Nicola 《Erwerbs-Obstbau》2018,60(3):187-193

The paper deals with the spatial distribution of root density in highbush blueberry plantations of various ages for a proper planting distance recommendation and a better irrigation and fertilization management. The environmental conditions consist of sandy-loamy soils and a continental temperate climate. Two highbush blueberry cultivars were studied, ‘Bluecrop’ and ‘Blueray’. Root density (RD) and density of root cross-sectional area (RCSA) were investigated for various root diameters. It was found that the prevalent type of roots in highbush blueberry crops is the hair type, with root diameters less than 0.1?mm. Both RD and RCSA decreased with distance from plant and with soil depth; the 38-year-old crop showed a more developed root system versus the 8?year-old crop. In both cases the roots did not grow more than 0.6?m laterally and more than 0.7?m deep. According to these results, the planting distances in highbush blueberry could be reduced to substantially increase the number of plants/ha and fruit yield. Irrigation application should be carried out to wet a proper soil volume, about 0.6–0.7?m deep for older crops, and about 0.5?m deep for younger crops.  相似文献   

Sperm cryopreservation in the Far‐Eastern wildcat (Prionailurus bengalensis euptilurus)          下载免费PDF全文

Sergei Amstislavsky  Eugeny Brusentsev  Elena Kizilova  Valentina Mokrousova  Valeria Kozhevnikova  Tatyana Abramova  Irina Rozhkova  Sergey Naidenko 《Reproduction in domestic animals》2018,53(5):1219-1226

The Far‐Eastern wildcat (Prionailurus bengalensis euptilurus) is a rare and poorly investigated nondomestic felid species. An attempt of freezing and cryopreserving Far‐Eastern wildcat spermatozoa in CaniPlus Freeze (CPF) medium is reported. Sperm was collected by electroejaculation from five adult Far‐Eastern wildcat captive‐born males. Epididymal spermatozoa from five adult randomly bred domestic cat males were used as a reference. The viability of frozen–thawed spermatozoa evaluated by double staining with SYBR Green I and PI followed by the subsequent confocal laser scanning microscopy (CLSM) was 38.2% ± 3.0% for the domestic cat and 38.0% ± 10.2% for the Far‐Eastern wildcat. The motility of frozen–thawed spermatozoa was 30.8% ± 9.8% for the domestic cat and 33.7% ± 15.1% for the Far‐Eastern wildcat. Sperm morphology was assessed by light microscopy. The total percentage of normal spermatozoa after freezing and thawing was 51.9 ± 5.9 for the domestic cat and 55.0% ± 6.4% for the Far‐Eastern wildcat. Defects of flagella were the most frequently observed abnormalities in both species (32.2% ± 4.8% and 30.8% ± 4.4% of all reported anomalies for the domestic cat and Far‐Eastern wildcat, respectively). Domestic cat epididymal and Far‐Eastern ejaculatory spermatozoa fertilized in vitro‐matured oocytes of the domestic cat (30.0% ± 5.5% and 35.5% ± 15.0%, respectively). Taken together, these results suggest that the freezing of Far‐Eastern wildcat spermatozoa with CPF medium is a suitable method for Felidae cryopreservation.  相似文献   

An open label clinical trial to evaluate the utility of a hydrolysed fish and rice starch elimination diet for the diagnosis of adverse food reactions in dogs          下载免费PDF全文

Irina Matricoti  Chiara Noli 《Veterinary dermatology》2018,29(5):408-e134

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A Non-Gaussian Spatial Generalized Linear Latent Variable Model     

Irina Irincheeva  Eva Cantoni  Marc G. Genton 《Journal of Agricultural, Biological & Environmental Statistics》2012,17(3):332-353

We consider a spatial generalized linear latent variable model with and without normality distributional assumption on the latent variables. When the latent variables are assumed to be multivariate normal, we apply a Laplace approximation. To relax the assumption of marginal normality in favor of a mixture of normals, we construct a multivariate density with Gaussian spatial dependence and given multivariate margins. We use the pairwise likelihood to estimate the corresponding spatial generalized linear latent variable model. The properties of the resulting estimators are explored by simulations. In the analysis of an air pollution data set the proposed methodology uncovers weather conditions to be a more important source of variability than air pollution in explaining all the causes of non-accidental mortality excluding accidents.  相似文献   

Accumulation of coal humic acids by wheat seedlings: Direct evidence using tritium autoradiography and occurrence in lipid fraction          下载免费PDF全文

Natalia A. Kulikova  Gennadii A. Badun  Viktor I. Korobkov  Maria G. Chernysheva  Eugenia A. Tsvetkova  Dmitry P. Abroskin  Andrey I. Konstantinov  Boris T. Zaitchik  Alexander O. Ruzhitsky  Irina V. Perminova 《植物养料与土壤学杂志》2014,177(6):875-883

Humic acids (HA) are natural organic compounds that are important components of organic matter. The accumulation, distribution, and fate of tritium‐labeled HA prepared from coal were analyzed using wheat (Triticum aestivum L.) seedlings. There was a period of rapid accumulation of HA followed by a slower one in the period from 1 to 24 h. There was a significant decrease in HA accumulation at low temperature, indicating that the slower rate of HA accumulation represented a membrane‐mediated process. HA distribution in plant tissues was analyzed using autoradiography. In all cases, HA concentration was considerably higher in the roots than in the shoots. Detailed examination of autoradiograms showed that there was preferential accumulation of HA in the apices of roots and shoots of wheat seedlings. Lipid fractions were extracted from seedlings and analyzed with thin layer chromatography and gas chromatography–mass spectrometry. These analyses revealed that labeled HA were present in the neutral lipid fraction consisting mainly of alkanes and alkenes, which are usually found in plant waxes, associated with the cuticle and suberized tissues. Based on these data, it is suggested that HA‐derived hydrocarbons may be used in wax biosynthesis. This role could explain the mitigating activity of humic substances under stress conditions.  相似文献