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101.
The syntheses and molecular structures of six- and five-coordinated rhodium(III) corroles (by pyridines and a chiral amine, respectively) and the rhodium(I) complex of a chiral corrole are described, together with some interesting features in the NMR spectra of the complexes and their utilization as carbene-transfer catalysts. 相似文献
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The influence of scale and patchiness on spider diversity in a semi-arid environment 总被引:2,自引:0,他引:2
Semi-arid scrubland in the Middle East consists of a soil crust matrix overlain with patches of perennial shrubs. To understand factors influencing biodiversity in this vulnerable landscape we need to understand how this mosaic of habitats influences associated fauna. Spiders are particularly abundant in this habitat so we asked if spider diversity differed between habitat patches and if different patch types contained either a subset of the regional species pool or specific species guilds. We also asked whether changes in the fractal nature of the microphytic and macrophytic patch mosaic altered spider diversity in this habitat. We found that the semi-arid scrubland at Sayeret Shaked Park (Israel) contains different spider communities that require patches of a certain quality to develop fully. Different patch types contain communities of different species, but the community structure of the patches is similar. We suggest that large-scale environmental factors typical of the site as a whole influence coarse-grained community structure, while small-scale differences between patch types result in the specialisation of species to different patch types. 相似文献
105.
Summary Recombinant protein G (RPG) was conjugated to colloidal gold particles and used for immunocytochemistry. In this report, the preparation of RPG—gold conjugates (RPGG) and the application of these conjugates in spot blot tests and in double immunolabelling are described. The immunolabelling was performed on ultracryosections of pig small intestine using antibodies directed against aminopeptidase N and sucrase—isomaltase. The labelling efficiency of RPGG was compared to that of protein A—gold conjugates (PAG) in different compartments of the enterocyte. Quantification showed that the labelling intensity was dependent on the size of the marker as well as on the kind of protein used for complex formation. The distributions for RPGG and PAG were respectively: for the 12nm particles, 10.3 and 6.2 particles/µm of length of microvillar membrane, 3.5 and 1.0 particles/µm2 of Golgi profile and 5.9 and 2.0 particles/µm2 of multivesicular body profile; and for the 6nm particles, 49.6 and 15.7 particles/µm of length of microvillar membrane, 24.4 and 5.0 particles/µm2 of Golgi profile and 25.4 and 3.4. particles/µm2 of multivesicular body profile. Controls showed very little non-specific gold labelling (<0.02 gold particles/µm2 of section). 相似文献
106.
Amir Eldar Haim Rozenberg Yael Diskin-Posner Remo Rohs Zippora Shakked 《Nucleic acids research》2013,41(18):8748-8759
A p53 hot-spot mutation found frequently in human cancer is the replacement of R273 by histidine or cysteine residues resulting in p53 loss of function as a tumor suppressor. These mutants can be reactivated by the incorporation of second-site suppressor mutations. Here, we present high-resolution crystal structures of the p53 core domains of the cancer-related proteins, the rescued proteins and their complexes with DNA. The structures show that inactivation of p53 results from the incapacity of the mutated residues to form stabilizing interactions with the DNA backbone, and that reactivation is achieved through alternative interactions formed by the suppressor mutations. Detailed structural and computational analysis demonstrates that the rescued p53 complexes are not fully restored in terms of DNA structure and its interface with p53. Contrary to our previously studied wild-type (wt) p53-DNA complexes showing non-canonical Hoogsteen A/T base pairs of the DNA helix that lead to local minor-groove narrowing and enhanced electrostatic interactions with p53, the current structures display Watson–Crick base pairs associated with direct or water-mediated hydrogen bonds with p53 at the minor groove. These findings highlight the pivotal role played by R273 residues in supporting the unique geometry of the DNA target and its sequence-specific complex with p53. 相似文献
107.
Leor Zach David Guez David Last Dianne Daniels Yuval Grober Ouzi Nissim Chen Hoffmann Dvora Nass Alisa Talianski Roberto Spiegelmann Zvi R. Cohen Yael Mardor 《PloS one》2012,7(12)
The current standard of care for newly diagnosed glioblastoma multiforme (GBM) is resection followed by radiotherapy with concomitant and adjuvant temozolomide. Recent studies suggest that nearly half of the patients with early radiological deterioration post treatment do not suffer from tumor recurrence but from pseudoprogression. Similarly, a significant number of patients with brain metastases suffer from radiation necrosis following radiation treatments. Conventional MRI is currently unable to differentiate tumor progression from treatment-induced effects. The ability to clearly differentiate tumor from non-tumoral tissues is crucial for appropriate patient management. Ten patients with primary brain tumors and 10 patients with brain metastases were scanned by delayed contrast extravasation MRI prior to surgery. Enhancement subtraction maps calculated from high resolution MR images acquired up to 75 min after contrast administration were used for obtaining stereotactic biopsies. Histological assessment was then compared with the pre-surgical calculated maps. In addition, the application of our maps for prediction of progression was studied in a small cohort of 13 newly diagnosed GBM patients undergoing standard chemoradiation and followed up to 19.7 months post therapy. The maps showed two primary enhancement populations: the slow population where contrast clearance from the tissue was slower than contrast accumulation and the fast population where clearance was faster than accumulation. Comparison with histology confirmed the fast population to consist of morphologically active tumor and the slow population to consist of non-tumoral tissues. Our maps demonstrated significant correlation with perfusion-weighted MR data acquired simultaneously, although contradicting examples were shown. Preliminary results suggest that early changes in the fast volumes may serve as a predictor for time to progression. These preliminary results suggest that our high resolution MRI-based delayed enhancement subtraction maps may be applied for clear depiction of tumor and non-tumoral tissues in patients with primary brain tumors and patients with brain metastases. 相似文献
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109.
Yael Klin Alexander Zlotnik Matthew Boyko Yoram Shapira 《Biochemical and biophysical research communications》2010,399(4):694-698
Excess l-glutamate (glutamate) levels in brain interstitial and cerebrospinal fluids (ISF and CSF, respectively) are the hallmark of several neurodegenerative conditions such as stroke, traumatic brain injury or amyotrophic lateral sclerosis. Its removal could prevent the glutamate excitotoxicity that causes long-lasting neurological deficits. As in previous studies, we have established the role of blood glutamate levels in brain neuroprotection, we have now investigated the contribution of the peripheral organs to the homeostasis of glutamate in blood. We have administered naive rats with intravenous injections of either l-[1-14C] Glutamic acid (l-[1-14C] Glu), l-[G-3H] Glutamic acid (l-[G-3H] Glu) or d-[2,3-3H] Aspartic acid (d-[2,3-3H] Asp), a non-metabolized analog of glutamate, and have followed their distribution into peripheral organs. We have observed that the decay of the radioactivity associated with l-[1-14C] Glu and l-[G-3H] Glu was faster than that associated with glutamate non-metabolized analog, d-[2,3-3H] Asp. l-[1-14C] Glu was subjected in blood to a rapid decarboxylation with the loss of 14CO2. The three major sequestrating organs, serving as depots for the eliminated glutamate and/or its metabolites were skeletal muscle, liver and gut, contributing together 92% or 87% of total l-[U-14C] Glu or d-[2,3-3H] Asp radioactivity capture. l-[U-14C] Glu and d-[2,3-3H] Asp showed a different organ sequestration pattern. We conclude that glutamate is rapidly eliminated from the blood into peripheral tissues, mainly in non-metabolized form. The liver plays a central role in glutamate metabolism and serves as an origin for glutamate metabolites that redistribute into skeletal muscle and gut. The findings of this study suggest now that pharmacological manipulations that reduce the liver glutamate release rate or cause a boosting of the skeletal muscle glutamate pumping rate are likely to cause brain neuroprotection. 相似文献
110.
Shilman Florin Brand Yael Brand Arnon Hedvat Ilan Hovav Ran 《Plant Molecular Biology Reporter》2011,29(1):232-241
The stearoyl–acyl carrier protein (ACP) desaturase (SAD) is a nuclear-encoded, plastid-localized soluble desaturase that catalyzes the
conversion of stearoyl-ACP to oleoyl-ACP and plays a key role in the determination of the properties of the majority of cellular
glycerolipids. Sad genes from a variety of plant species have been cloned and characterized. However, in peanut (Arachis hypogaea), an important edible and oilseed crop, these genes have not yet been characterized. By searching peanut expressed sequence
tag (EST) and parallel sequencing (454) libraries, we have identified three members of the ahSad gene family. Among them, only one gene, ahSad3, was exclusively expressed during seed development and in a manner fully corresponding to oil accumulation. Both ahSad3 homeologous genes (ahSad3A and ahSad3B) were recovered from the allotetraploid peanut, and their mRNA expression levels were characterized. The open reading frames
for ahSad3A and ahSad3B are 98% identical and consist of 1,158 bp, encoding a 386-full-amino-acid protein, with one intron in the coding sequence.
Comparisons of the sequences of these two homeologous genes revealed seven single-nucleotide polymorphisms and one triplet
insertion in the coding region. Southern blot analysis indicated that there are only two copies of the ahSad3 gene in the peanut genome. Homeolog-specific gene expression analysis showed that both ahSad3 homeologs are expressed in developing seeds, but gene expression is significantly biased toward the B genome. Our results
point to ahSad3 as a possible target gene for manipulation of fatty acid saturation in A. hypogaea. 相似文献