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排序方式: 共有336条查询结果,搜索用时 15 毫秒
101.
Marco Porceddu Efisio Mattana Hugh W. Pritchard Gianluigi Bacchetta 《Annals of botany》2013,112(9):1887-1897
Background and Aims
Mediterranean mountain species face exacting ecological conditions of rainy, cold winters and arid, hot summers, which affect seed germination phenology. In this study, a soil heat sum model was used to predict field emergence of Rhamnus persicifolia, an endemic tree species living at the edge of mountain streams of central eastern Sardinia.Methods
Seeds were incubated in the light at a range of temperatures (10–25 and 25/10 °C) after different periods (up to 3 months) of cold stratification at 5 °C. Base temperatures (Tb), and thermal times for 50 % germination (θ50) were calculated. Seeds were also buried in the soil in two natural populations (Rio Correboi and Rio Olai), both underneath and outside the tree canopy, and exhumed at regular intervals. Soil temperatures were recorded using data loggers and soil heat sum (°Cd) was calculated on the basis of the estimated Tb and soil temperatures.Key Results
Cold stratification released physiological dormancy (PD), increasing final germination and widening the range of germination temperatures, indicative of a Type 2 non-deep PD. Tb was reduced from 10·5 °C for non-stratified seeds to 2·7 °C for seeds cold stratified for 3 months. The best thermal time model was obtained by fitting probit germination against log °Cd. θ50 was 2·6 log °Cd for untreated seeds and 2·17–2·19 log °Cd for stratified seeds. When θ50 values were integrated with soil heat sum estimates, field emergence was predicted from March to April and confirmed through field observations.Conclusions
Tb and θ50 values facilitated model development of the thermal niche for in situ germination of R. persicifolia. These experimental approaches may be applied to model the natural regeneration patterns of other species growing on Mediterranean mountain waterways and of physiologically dormant species, with overwintering cold stratification requirement and spring germination. 相似文献102.
Francesca D'Avila Cristina Tringali Nadia Papini Luigi Anastasia Gianluigi Croci Luca Massaccesi Eugenio Monti Guido Tettamanti Bruno Venerando 《Journal of cellular biochemistry》2013,114(1):204-211
The sialylation level of molecules, sialoglycoproteins and gangliosides, protruding from plasma membranes regulates multiple facets of erythrocyte function, from interaction with endothelium to cell lifespan. Our results demonstrate that: (a) Both sialidases NEU1 and NEU3 are present on erythrocyte plasma membrane; (b) NEU1 is kept on the plasma membrane in absence of the protective protein/cathepsin A (PPCA); (c) NEU1 and NEU3 are retained on the plasma membrane, as peripheral proteins, associated to the external leaflet and released by alkaline treatments; (d) NEU1 and NEU3 are segregated in Triton X‐100 detergent‐resistant membrane domains (DRMs); (e) NEU3 shows activity also at neutral pH; and (f) NEU1 and NEU3 are progressively lost during erythrocyte life. Interestingly, sialidase activity released from erythrocyte membranes after an alkaline treatment preserves its functionality and recognizes sialoglycoproteins and gangliosides. On the other hand, the weak anchorage of sialidases to the plasma membrane and their loss during erythrocyte life could be a tool to preserve the cellular sialic acid content in order to avoid the early ageing of erythrocyte and processes of cell aggregation in the capillaries. J. Cell. Biochem. 114: 204–211, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
103.
Francesco Dituri Antonio Mazzocca Fernando Juan Peidrò Patrizia Papappicco Isabel Fabregat Flavia De Santis Angelo Paradiso Carlo Sabbà Gianluigi Giannelli 《PloS one》2013,8(6)
We investigated blocking the TGF-β signaling pathway in HCC using two small molecule inhibitors (LY2157299, LY2109761) and a neutralizing humanized antibody (D10) against TGF-βRII. LY2157299 and LY2109761 inhibited HCC cell migration on Laminin-5, Fibronectin, Vitronectin, Fibrinogen and Collagen-I and de novo phosphorylation of pSMAD2. LY2157299 inhibited HCC migration and cell growth independently of the expression levels of TGF-βRII. In contrast to LY2157299, D10 showed a reduction in pSMAD2 only after a short exposure. This study supports the use of LY2157299 in clinical trials, and presents new insights into TGF-β receptor cycling in cancer cells. 相似文献
104.
105.
Mote KR Gopinath T Traaseth NJ Kitchen J Gor'kov PL Brey WW Veglia G 《Journal of biomolecular NMR》2011,51(3):339-346
Oriented solid-state NMR is the most direct methodology to obtain the orientation of membrane proteins with respect to the
lipid bilayer. The method consists of measuring 1H-15N dipolar couplings (DC) and 15N anisotropic chemical shifts (CSA) for membrane proteins that are uniformly aligned with respect to the membrane bilayer.
A significant advantage of this approach is that tilt and azimuthal (rotational) angles of the protein domains can be directly
derived from analytical expression of DC and CSA values, or, alternatively, obtained by refining protein structures using
these values as harmonic restraints in simulated annealing calculations. The Achilles’ heel of this approach is the lack of
suitable experiments for sequential assignment of the amide resonances. In this Article, we present a new pulse sequence that
integrates proton driven spin diffusion (PDSD) with sensitivity-enhanced PISEMA in a 3D experiment ([1H,15N]-SE-PISEMA-PDSD). The incorporation of 2D 15N/15N spin diffusion experiments into this new 3D experiment leads to the complete and unambiguous assignment of the 15N resonances. The feasibility of this approach is demonstrated for the membrane protein sarcolipin reconstituted in magnetically
aligned lipid bicelles. Taken with low electric field probe technology, this approach will propel the determination of sequential
assignment as well as structure and topology of larger integral membrane proteins in aligned lipid bilayers. 相似文献
106.
Gaffarogullari EC Masterson LR Metcalfe EE Traaseth NJ Balatri E Musa MM Mullen D Distefano MD Veglia G 《Journal of molecular biology》2011,411(4):823-836
The cAMP-dependent protein kinase [protein kinase A (PKA)] mediates a myriad of cellular signaling events, and its activity is tightly regulated in both space and time. Among these regulatory mechanisms is N-myristoylation, whose biological role has been elusive. Using a combination of thermodynamics, kinetics, and spectroscopic methods, we analyzed the effects of N-myristoylation and phosphorylation at Ser10 on the interactions of PKA with model membranes. We found that, in the absence of lipids, the myristoyl group is tucked into the hydrophobic binding pocket of the enzyme (myr-in state). Upon association with lipid bilayers, the myristoyl group is extruded and inserts into the hydrocarbon region of the lipid bilayer (myr-out state). NMR data indicate that the enzyme undergoes conformational equilibrium between myr-in and myr-out states, which can be shifted byeither interaction with membranes and/or phosphorylation at Ser10. Our results provide evidence that the membrane binding motif of the myristoylated C-subunit of PKA (PKA-C) steers the enzyme toward lipids independent of its regulatory subunit or an A-kinase anchoring protein, providing an additional mechanism to localize the enzyme near membrane-bound substrates. 相似文献
107.
Brieda M De Mattia L Dametto E Del Bianco F Nicolosi G 《Indian pacing and electrophysiology journal》2011,11(6):176-179
Upgrading of a pacing system in the presence of a subclavian occlusion is technically challenging. We describe the case of a patient who underwent a successful upgrading procedure of an implantable cardioverter-defibrillator (ICD) to a biventricular defibrillator (ICD-CRT) in the presence of a suboccluded left subclavian vein, using a collateral vein that drained into the contralateral subclavian vein. 相似文献
108.
Gorgoglione V Laraspata D La Piana G Marzulli D Lofrumento NE 《Archives of biochemistry and biophysics》2007,461(1):13-23
The data reported are fully consistent with the well-known observation that exogenous cytochrome c (cyto-c) molecules do not permeate through the outer membrane of mitochondria (MOM) incubated in isotonic medium (250 mM sucrose). Cyto-c is unable to accept electrons from the sulfite/cyto-c oxido-reductase (Sox) present in the intermembrane space, unless mitochondria are solubilized. Mitochondria incubated in a very high hypotonic medium (25 mM sucrose), in contrast to any expectation, continue to be not permeable to added cyto-c even if Sox and adenylate kinase are released into the medium. The succinate/exogenous cyto-c reductase activity, very low in isotonic medium, is greatly increased decreasing the osmolarity of the medium but in both cases remains insensitive to proteolysis by added trypsin. In hypotonic medium, magnesium and potassium ions have a protective effect on the release of enzymes and on the reactivity of cyto-c as electron acceptor from both sulfite and succinate; results which are consistent with the view that MOM preserves its identity and remains not permeable to exogenous cyto-c. This report strengthens the proposal, supported by previously published data that in isotonic medium the exogenous NADH/cyto-c electron transport system is catalyzed by intact mitochondria, not permeable to added cyto-c. 相似文献
109.
An electrochemical investigation of sarcolipin reconstituted into a mercury-supported lipid bilayer
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Sarcolipin was incorporated into a lipid bilayer anchored to a mercury electrode through a hydrophilic tetraethyleneoxy chain. The behavior of this tethered bilayer lipid membrane incorporating sarcolipin was investigated by electrochemical impedance spectroscopy and by recording charge versus time curves after potential jumps. When the transmembrane potential starts to become negative on the trans side, evidence is provided that sarcolipin aggregates into ion-conducting pores. Over the range of physiological transmembrane potentials, these pores are permeable to small inorganic anions such as chloride, phosphate, or sulfate but impermeable to inorganic cations such as Na+ and K+. Only at transmembrane potentials more negative than approximately -150 mV on the trans side do sarcolipin channels allow the translocation of the latter cations. A tentative relationship between this property of sarcolipin and its regulatory function on Ca-ATPase of sarcoplasmic reticulum is proposed. 相似文献
110.
Simultaneous Detection of Pseudomonas fragi, P. lundensis, and P. putida from Meat by Use of a Multiplex PCR Assay Targeting the carA Gene
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Danilo Ercolini Federica Russo Giuseppe Blaiotta Olimpia Pepe Gianluigi Mauriello Francesco Villani 《Applied microbiology》2007,73(7):2354-2359
Species-specific primers and a multiplex PCR assay were developed for the simultaneous identification and differentiation of Pseudomonas fragi, P. lundensis, and P. putida based on the coamplification of different portions of the small subunit of the carbamoyl phosphate synthase gene (carA). The carA multiplex PCR was used to detect the presence of the three Pseudomonas species from beef, chicken, and pork samples and proved to be effective in showing their evolution during the storage of meat. 相似文献