Structure of the LDL receptor extracellular domain at endosomal pH   总被引：2，自引：0，他引：2  

Rudenko G  Henry L  Henderson K  Ichtchenko K  Brown MS  Goldstein JL  Deisenhofer J 《Science (New York, N.Y.)》2002,298(5602):2353-2358

The low-density lipoprotein receptor mediates cholesterol homeostasis through endocytosis of lipoproteins. It discharges its ligand in the endosome at pH < 6. In the crystal structure at pH = 5.3, the ligand-binding domain (modules R2 to R7) folds back as an arc over the epidermal growth factor precursor homology domain (the modules A, B, beta propeller, and C). The modules R4 and R5, which are critical for lipoprotein binding, associate with the beta propeller via their calcium-binding loop. We propose a mechanism for lipoprotein release in the endosome whereby the beta propeller functions as an alternate substrate for the ligand-binding domain, binding in a calcium-dependent way and promoting lipoprotein release.  相似文献   

Size and Geographical Variation in PM1, PM2.5 and PM10: Source Profiles from Soils in the Western United States     

Labban  Raed  Veranth  John M.  Chow  Judith C.  Engelbrecht  Johann L. P.  Watson  John G. 《Water, air, and soil pollution》2004,157(1-4):13-31

Source profiles (fractional mass abundances and uncertainties) for use in chemical mass balance (CMB) source apportionment are reported for soil dust from unpaved roads and desert lands. The objectives were to add to the library of source composition profiles available for CMB studies, and to provide data on the variation in wind-blown dust composition between particle sizes and geographical locations. Samples were resuspended and sampled through PM₁, PM_2.5 and PM₁₀ inlets onto filters, then chemically analyzed for 40 elements, seven ions and eight carbon fractions. Air quality management would benefit from technology that can distinguish soil dust from sites in different geographical locations and sites with different land uses. Five geographical clusters representing Ft Bliss, TX, Dona Ana County, NM, Ft Irwin, CA, the west desert and the Canyonlands, UT, were examined. Distinctive differences were found between sites within a cluster and these differences were comparable to the differences between cluster averages. Some sites showed small differences in chemical composition between particle sizes, but these differences were less than the differences observed between nearby geographical locations. Dust emissions from sites with uniform geology have distinctive source profiles that may be useful for CMB receptor modeling. Heterogeneous regions, defined by land management boundaries, will require extensive field sampling to develop representative composite source profiles.  相似文献   

Korrelationen von Enzymaktivitäten im Boden     

Johann Hofmann  Anton Pfitscher 《植物养料与土壤学杂志》1982,145(1):36-41

Correlations of Enzyme-Activities in Soil Enzyme-activities often have been used as indicators of the biological state of soil. In this connection some questions may be posed: Which enzyme is the best indicator of biological activities in soil, what is the relationship of enzyme-activities to other ecological parameters and what is the interdependency between different enzymes? To answer these questions we measured activities of amylase, catalase, invertase, pectinase, urease, xylanase and cellulase at nine alpine and subalpine sites. Furthermore the CO₂-evolution, contens of nitrogen, carbon, organic matter, the soil density, total bacterial number and water capacity were determined. With these data correlation coefficients were calculated. The best relationships were found between cellulase-xylanase and amylase-invertase activities (Table 1). While catalase and pectinase are in the middle range, urease shows relatively low values. There are highly significant correlations between enzyme-activities and the content of nitrogen, carbon, organic matter, soil density or the CO₂-evolution (number of samples used for calculations was 68). Almost no correlations were found with total bacterial count (Table 2). For these calculations 34 samples of each parameter were used. To prove that the lower number of samples is not the reason for low correlation coefficients we computed data of 17 samples (Table 3). The water capacity is depending on soil density and content of organic matter and the correlations are in the same range (Comparison Table 1 and 3). This means that 17 samples of each parameter are enough for these calculations. Enzyme-activities proof therefore to be good indicators of the biological state of soil. It is inappropriate to characterise biological activities of soil by total bacterial counts only.  相似文献   

Soybean cadmium concentration: validation of a QTL affecting seed cadmium accumulation for improved food safety     

Johann Vollmann  Tomáš Lošák  Martin Pachner  Daisuke Watanabe  Ludmila Musilová  Jaroslav Hlušek 《Euphytica》2015,203(1):177-184

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Implications for dosing regimen of enrofloxacin administered concurrently with dexamethasone in febrile buffalo calves     

Sidhu  Pritam K.  Ramalingam  Balaje  Kaur  Gurpreet  Rampal  Satyavan  Coetzee  Johann F. 《Tropical animal health and production》2020,52(3):1093-1102

Tropical Animal Health and Production - The objective of the study was to determine the influence of dexamethasone (DXM) on pharmacokinetics (PK) and pharmacodynamics (PD) of enrofloxacin (ENR) for...  相似文献   

Dynamic use of coastal areas by bull sharks and the conciliation of conservation and management of negative human–wildlife interactions     

Johann Mourier  Marc Soria  Antonin Blaison  Monique Simier  Grégoire Certain  Angélique Demichelis  Tarek Hattab 《水产资源保护:海洋与淡水生态系统》2021,31(10):2926-2937

1. Knowledge about spatial and temporal variability in the distribution and abundance of predators is necessary to adapt measures to mitigate human–wildlife interactions.
2. Acoustic telemetry and network analyses were used to investigate the spatial ecology of bull sharks, the species responsible for most shark bites in Reunion Island, one of the world's shark bite hotspots.
3. The west coast of the island was not used uniformly by every individual, with size predicting the movements of sharks along the coast.
4. Node-based metrics – closeness, node strength, and cumulated continuous residency times – derived from up to 181 monthly movement networks from 20 individuals, revealed that smaller sharks (<250 cm total length) primarily used the south-west coast while larger individuals spent most of their time in the northern region with regular visits to multiple areas along the coast.
5. This study provides essential knowledge on bull shark behaviour and central areas used at different periods of the year, which correlates well with the dynamics of observed shark bites. Our approach provides a non-invasive alternative to help predicting and anticipating human–shark conflicts and avoid shark culling programmes detrimental to the conservation of large predators such as sharks.

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Degradation of Cry1Ab protein from genetically modified maize in the bovine gastrointestinal tract     

Lutz B  Wiedemann S  Einspanier R  Mayer J  Albrecht C 《Journal of agricultural and food chemistry》2005,53(5):1453-1456

Immunoblotting assays using commercial antibodies were established to investigate the unexpected persistence of the immunoactive Cry1Ab protein in the bovine gastrointestinal tract (GIT) previously suggested by enzyme-linked immunosorbent assay (ELISA). Samples of two different feeding experiments in cattle were analyzed with both ELISA and immunoblotting methods. Whereas results obtained by ELISA suggested that the concentration of the Cry1Ab protein increased during the GIT passage, the immunoblotting assays revealed a significant degradation of the protein in the bovine GIT. Samples showing a positive signal in the ELISA consisted of fragmented Cry1Ab protein of approximately 17 and 34 kDa size. Two independent sets of gastrointestinal samples revealed the apparent discrepancy between the results obtained by ELISA and immunoblotting, suggesting that the antibody used in the ELISA reacts with fragmented yet immunoactive epitopes of the Cry1Ab protein. It was concluded that Cry1Ab protein is degraded during digestion in cattle. To avoid misinterpretation, samples tested positive for Cry1Ab protein by ELISA should be reassessed by another technique.  相似文献   

Intraobserver and interobserver agreement for results of low-field magnetic resonance imaging in dogs with and without clinical signs of disk-associated wobbler syndrome     

De Decker S  Gielen IM  Duchateau L  Lang J  Dennis R  Corzo-Menéndez N  van Bree HJ  Van Soens I  Binst DH  Waelbers T  Van Ham LM 《Journal of the American Veterinary Medical Association》2011,238(1):74-80

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Effect of flunixin meglumine on the amelioration of lameness in dairy steers with amphotericin B-induced transient synovitis-arthritis     

Schulz KL  Anderson DE  Coetzee JF  White BJ  Miesner MD 《American journal of veterinary research》2011,72(11):1431-1438

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LOW-FIELD MAGNETIC RESONANCE IMAGING OF A PYOCEPHALUS AND A SUSPECTED BRAIN ABSCESS IN A GERMAN SHEPHERD DOG     

Gabriela  Seiler  Dr. Med. Vet.  Sigitas  Cizinauskas  Dr. Med. Vet.  Jürg  Scheidegger  Dr. Med. FMH  Johann  Lang  Dr. Med. Vet. 《Veterinary radiology & ultrasound》2001,42(5):417-422

Magnetic resonance imaging was performed on an eight-year-old, neutered female German Shepherd dog with a history of acute depression, inappetence, and hyperthermia. A lesion in the cerebrum was suspected. Possible differential diagnoses were meningoencephalitis, neoplasia, and vascular lesion (infarction, bleeding). A ring enhancing lesion was found in the basal ganglia on the left side with edema of the surrounding brain tissue. A similar mass lesion was present in the right pterygoid musculature. With inversion recovery sequences an altered composition of the cerebrospinal fluid (CSF) in the left lateral ventricle could be detected. CSF analysis confirmed a pyocephalus, probably due to rupture of a brain abscess into the left lateral ventricle.  相似文献