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排序方式: 共有390条查询结果,搜索用时 62 毫秒
1.
Plants of Solanum tuberosum L. potato do not cold acclimate when exposed to low temperature such as 5°C, day/night. When ABA (45 M) was added to the culture medium, stem-cultured plantlets of S. tuberosum, cv. Red Pontiac, either grown at 20°C/15°C, day/night, or at 5°C, increased in cold hardiness from –2°C (killing temperature) to –4.5°C. The increase in cold hardiness could be inhibited in both temperature regimes if cycloheximide (70 M) was added to the culture medium at the inception of ABA treatment. Cycloheximide did not inhibit cold hardiness development, however, when it was added to the culture medium 3 days after ABA treatment.When pot-grown plants were foliar sprayed with mefluidide (50 M), ABA content increased from 10 nmol to 30 nmol g–1 dry weight and plants increased in cold hardiness from –2°C to about –3.5°C. The increases in free ABA and cold hardiness occurred only in plants grown at 20°C/15°C; neither ABA nor cold hardiness increased in plants grown at 5°C.The results suggest that an increase in ABA and a subsequent de novo synthesis of proteins are required for the development of cold hardiness in S. tuberosum regardless of temperature regime, and that the inability to synthesize ABA at low temperature, rather than protein synthesis, appears to be the reason why S. tuberosum does not cold acclimate. 相似文献
2.
The role of rapidly exchanging intracellular Ca2+ stores in the control of Ca2+ homeostasis is reviewed. The following issues are discussed: the reasons why such stores exist in eukaryotic cells; the differences between the terminal cisternae of the skeletal muscle sarcoplasmic reticulum, which have direct, physical connection with the T tubules of the plasmalemma, and the Ca2+ stores located in the depth of the cytoplasm, which are stimulated by second messengers; the cytological nature (subcompartments of the ER) of the rapidly exchanging Ca2+ stores and their functional significance. The conclusions introduce recent developments in which intracellular Ca2+ stores have been investigated also by molecular biology techniques. 相似文献
3.
Gaetano Barbato Daniel O. Cicero Elisabetta Bianchi Antonello Pessi Renzo Bazzo 《Journal of biomolecular NMR》1996,8(1):36-48
Summary We describe the high-resolution structure by NMR of two peptides that belong to a combinatorial library based on the zinc-finger motif. The library represents, to the best of our knowledge, the first example of a conformationally homogeneous peptide library and was obtained by introducing random residues in five positions of the -helical portion of a 26-residue consensus peptide (CP1) belonging to the Cys2-Hys2 zinc-finger family. The result was shown to be a highly homogeneous -helical library (Bianchi et al., 1995). The structures of the parent compound (CP1) and of a representative member (CP1m) that was selected by screening the library with a monoclonal antibody are compared in detail as an example of the very high stability of the zinc-finger scaffold upon sequence variability. The two peptides exhibit an extremely high degree of structural similarity. The use of this type of conformationally constrained combinatorial library might represent a step forward in the design of peptidomimetics, as it considerably accelerates the process of the identification of the spatial relationship among the pharmacophoric groups.Abbreviations
t-Bu
tert-butyloxycarbonyl
- Fmoc
9-fluorenylmethoxycarbonyl 相似文献
4.
Vittorio Moretto Fernando Formaggio Marco Crisma Gian Maria Bonora Claudio Toniolo Ettore Benedetti Antonello Santini Michele Saviano Benedetto Di Blasio Carlo Pedone 《Journal of peptide science》1996,2(1):14-27
A complete series of terminally blocked, monodispersed homo-oligopeptides (to the pentamer level) from the sterically demanding, medium-ring alicyclic Cα,α-disubstituted glycine 1-aminocyclooctane-1-carb oxylic acid (Ac8c), and two Ala/Ac8c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and 1H-NMR. The molecular structures of the amino acid derivative Z-Ac8c-OH, the dipeptide pBrBz- (Ac8c)2-OH and the tripeptide pBrBz-(Ac8c)3-OtBu were assessed in the crystal state by X-ray diffraction. Conformational energy computations were performed on the monopeptide Ac-Ac8c-NHMe. Taken together, the results obtained strongly support the view that the Ac8c residue is an effective β-turn and helix former. A comparison is also made with the conformational preferences of α-aminoisobutyric acid, the prototype of Cα, α-disubstituted glycines, and of the other members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n=3, 5–7) investigated so far. The implications for the use of the Ac8c residue in peptide conformational design are considered. 相似文献
5.
Michele Rechia Fighera Juliana Sartori Bonini Roberto Frussa-Filho Carlos Severo Dutra-Filho Martine E. Kienzle Hagen Maribel Antonello Rubin 《Free radical research》2013,47(5):495-500
Monosialoganglioside (GM1) is a neuroprotective agent that has been reported to scavenge free radicals generated during reperfusion and to protect receptors and enzymes from oxidative damage. However, only a few studies have attempted to investigate the effects of GM1 on enzymatic antioxidant defenses of the brain. In the present study, we evaluate the effects of the systemic administration of GM1 on the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), and on spontaneous chemiluminescence and total radical-trapping potential (TRAP) in cerebral cortex of rats ex vivo. The effects of GM1 on CAT activity and spontaneous chemiluminescence in vitro were also determined.Animals received two injections of GM1 (50?mg/kg, i.p.) or saline (0.85% NaCl, i.p.) spaced 24?h apart. Thirty minutes after the second injection the animals were sacrificed and enzyme activities and spontaneous chemiluminescence and TRAP were measured in cell-free homogenates. GM1 administration reduced spontaneous chemiluminescence and increased catalase activity ex vivo, but had no effect on TRAP, SOD or GSH-Px activities. GM1, at high concentrations, reduced CAT activity in vitro. We suggest that the antioxidant activity of GM1 ganglioside in the cerebral cortex may be due to an increased catalase activity. 相似文献
6.
Aldo Scarpa Katarzyna Sikora Matteo Fassan Anna Maria Rachiglio Rocco Cappellesso Davide Antonello Eliana Amato Andrea Mafficini Matilde Lambiase Claudia Esposito Emilio Bria Francesca Simonato Maria Scardoni Giona Turri Marco Chilosi Giampaolo Tortora Ambrogio Fassina Nicola Normanno 《PloS one》2013,8(11)
Identification of driver mutations in lung adenocarcinoma has led to development of targeted agents that are already approved for clinical use or are in clinical trials. Therefore, the number of biomarkers that will be needed to assess is expected to rapidly increase. This calls for the implementation of methods probing the mutational status of multiple genes for inoperable cases, for which limited cytological or bioptic material is available. Cytology specimens from 38 lung adenocarcinomas were subjected to the simultaneous assessment of 504 mutational hotspots of 22 lung cancer-associated genes using 10 nanograms of DNA and Ion Torrent PGM next-generation sequencing. Thirty-six cases were successfully sequenced (95%). In 24/36 cases (67%) at least one mutated gene was observed, including EGFR, KRAS, PIK3CA, BRAF, TP53, PTEN, MET, SMAD4, FGFR3, STK11, MAP2K1. EGFR and KRAS mutations, respectively found in 6/36 (16%) and 10/36 (28%) cases, were mutually exclusive. Nine samples (25%) showed concurrent alterations in different genes. The next-generation sequencing test used is superior to current standard methodologies, as it interrogates multiple genes and requires limited amounts of DNA. Its applicability to routine cytology samples might allow a significant increase in the fraction of lung cancer patients eligible for personalized therapy. 相似文献
7.
Alpine grouses are particularly vulnerable to climate change due to their adaptation to extreme conditions and to their relict distributions in the Alps where global warming has been particularly marked in the last half century. Grouses are also currently threatened by habitat modification and human disturbance, and an assessment of the impact of multiple stressors is needed to predict the fate of Alpine populations of these birds in the next decades. We estimated the effect of climate change and human disturbance on a rock ptarmigan population living in the western Italian Alps by combining an empirical population modelling approach and stochastic simulations of the population dynamics under the a1B climate scenario and two different disturbance scenarios, represented by the development of a ski resort, through 2050.The early appearance of snow-free ground in the previous spring had a favorable effect on the rock ptarmigan population, probably through a higher reproductive success. On the contrary, delayed snowfall in autumn had a negative effect possibly due to a mismatch in time to molt to white winter plumage which increases predation risk. The regional climate model PROTHEUS does not foresee any significant change in snowmelt date in the study area, while the start date of continuous snow cover is expected to be significantly delayed. The net effect in the stochastic projections is a more or less pronounced (depending on the model used) decline in the studied population. The addition of extra-mortality due to collision with ski-lift wires led the population to fatal consequences in most projections. Should these results be confirmed by larger studies the conservation of Alpine populations would deserve more attention. To counterbalance the effects of climate change, the reduction of all causes of death should be pursued, through a strict preservation of the habitats in the present area of occurrence. 相似文献
8.
Anna U. Eriksson Christoffer Svensson Andreas H?rnblad Abbas Cheddad Elena Kostromina Maria Eriksson Nils Norlin Antonello Pileggi James Sharpe Fredrik Georgsson Tomas Alanentalo Ulf Ahlgren 《Journal of visualized experiments : JoVE》2013,(71)
By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen''s (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)2; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction2 and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations3. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans. 相似文献
9.
Calabrò Marco Mandelli Laura Crisafulli Concetta Porcelli Stefano Albani Diego Politis Antonis Papadimitriou George N. Di Nicola Marco Janiri Luigi Colombo Roberto Martinotti Giovanni Bellomo Antonello Vieta Eduard Bonassi Stefano Frustaci Alessandra Ducci Giuseppe Landi Stefano Boccia Stefania Serretti Alessandro 《Molecular biology reports》2020,47(1):191-200
Molecular Biology Reports - Serotoninergic system is one of the most important neurotransmission systems investigated in the field of psychiatry. Extensive evidence reveals how alterations of this... 相似文献
10.
Filomena Sica Andrea Pica Antonello Merlino Irene Russo Krauss Carmine Ercole Delia Picone 《FEBS letters》2013
Bovine seminal ribonuclease (BS-RNase) acquires an interesting anti-tumor activity associated with the swapping on the N-terminal. The first direct experimental evidence on the formation of a C-terminal swapped dimer (C-dimer) obtained from the monomeric derivative of BS-RNase, although under non-native conditions, is here reported. The X-ray model of this dimer reveals a quaternary structure different from that of the C-dimer of RNase A, due to the presence of three mutations in the hinge peptide 111–116. The mutations increase the hinge peptide flexibility and decrease the stability of the C-dimer against dissociation. The biological implications of the structural data are also discussed. 相似文献