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61.
Colotta V Catarzi D Varano F Filacchioni G Martini C Trincavelli L Lucacchini A 《Bioorganic & medicinal chemistry》2003,11(24):5509-5518
In previous papers (Colotta, V. et al. Arch. Pharm. Pharm. Med. Chem. 1999, 332, 39. Colotta, V. et al. J. Med. Chem. 2000, 43, 1158) we reported the synthesis and binding affinity at bovine (b) A1 and A2A and human (h) A3 adenosine receptors (ARs) of the 4-amino-6-benzylamino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one (compound A) which resulted in a potent and selective A2A AR antagonist. Compound A provided the lead compound of a series of 6- or 8-(hetero)arylalkylamino-4-amino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives (compounds 1–20) which are the object of this paper. Most of the newly synthesized compounds are inactive at hA3 ARs while they possess both nanomolar bA2A affinities and different degrees of bA2A versus bA1 selectivity. The binding data show that hydrophilic substituents on the benzyl moiety are the most profitable for bA2A receptor affinity. Furthermore, their steric hindrance seems to play an important role for the bA2A AR interaction, thus suggesting that the 6-aralkylamino moiety of these ligands interacts with a size-limited binding pocket of this AR subtype. Thus, the SAR studies provided us some new insights about the structural requirements of the bA2A AR recognition site. 相似文献
62.
63.
Castiglia R Corti M Colangelo P Annesi F Capanna E Verheyen W Sichilima AM Makundi R 《Hereditas》2003,139(2):81-89
Aethomys is a common and widespread rodent genus in the African savannas and grasslands. However, its systematics and taxonomy are still unclear as no study has covered the entire range. In fact it might not be a monophyletic genus and perhaps should be split into two subgenera, Micaelamys and Aethomys. In this paper, we present findings based on the cytogenetics and the entire cytochrome b sequence of two species from Zambia (A. kaiseri) and Tanzania (A. chrysophilus), and we compare them with the sequences of a South African species (A. namaquensis) and other allied muroid genera. Comparison of the banded chromosomes revealed complete G-band homology between the autosomes of the two species. However, the X and Y chromosomes clearly differ in size and in C- and G-banding, being much larger in A. kaiseri. Comparison of the cytochrome b sequences places the separation between A. kaiseri and A. chrysophilus at 4.49 Mya, a period of intense speciation in other African muroids. The resulting phylogeny strongly supports the idea of a paraphyletic group, suggesting the need to elevate the previously described subgenera to the genus rank. 相似文献
64.
Quartacci MF Glisić O Stevanović B Navari-Izzo F 《Journal of experimental botany》2002,53(378):2159-2166
Plants of Ramonda serbica were dehydrated to 3.6% relative water content (RWC) by withholding water for 3 weeks, afterwards the plants were rehydrated for 1 week to 93.8% RWC. Plasma membranes were isolated from leaves using a two-phase aqueous polymer partition system. Compared with well-hydrated (control) leaves, dehydrated leaves suffered a reduction of about 75% in their plasma membrane lipid content, which returned to the control level following rewatering. Also the lipid to protein ratio decreased after dehydration, almost regaining the initial value after rehydration. Lipids extracted from the plasma membrane of fully-hydrated leaves were characterized by a high level of free sterols and a much lower level of phospholipids. Smaller amounts of cerebrosides, acylated steryl glycosides and steryl glycosides were also detected. The main phospholipids of control leaves were phosphatidylcholine and phosphatidylethanolamine, whereas sitosterol was the free sterol present in the highest amount. Following dehydration, leaf plasma membrane lipids showed a constant level of free sterols and a reduction in phospholipids compared with the well-hydrated leaves. Both phosphatidylcholine and phosphatidylethanolamine decreased following dehydration, their molar ratio remaining unchanged. Among free sterols, the remarkably high cholesterol level present in the control leaves (about 14 mol%) increased 2-fold as a result of dehydration. Dehydration caused a general decrease in the unsaturation level of individual phospholipids and total lipids as well. Upon rehydration the lipid composition of leaf plasma membranes restored very quickly approaching the levels of well-hydrated leaves. 相似文献
65.
66.
Pieri Pde C Pereira DH Glina S Hallak J McElreavey K Moreira-Filho CA 《Genetic testing》2002,6(3):185-194
PCR-based screening of microdeletions in the azoospermic factor (AZF) on the Yq chromosome is an accepted means of identifying a common genetic cause of male infertility, responsible for 5-15% of cases associated with a low sperm count (=5 x 10(6) sptz/ml). Based on an extensive analysis of the literature, we have established a cost-effective preliminary PCR-based diagnostic screening test, with a set of six pairs of primers ("set-of-6") that have the capability of detecting up to 95% of the Y microdeletion cases already published. These primers are: sY84 in AZFa, sY114, sY129, sY143 in AZFb, and sY149, sY254 in AZFc. Initially, the set-of-6 was tested with 13 other pairs of primers covering the three AZF subregions. A sample of 114 infertile men was tested and 10 (8.8%) microdeletions were found, 3 of which were among the 26 (11.5%) idiopathic azoospermic men. These results showed that all detected microdeletions would be identified using the set-of-6 only. Another sample of 34 patients was subsequently tested using the set-of-6 and 3 (8.8%) microdeletions were found in this group. A comparison of our results with those reported in the literature showed similar microdeletion detection frequencies, demonstrating that the set-of-6 primers provides a reliable, simple and cost-effective way of detecting AZF deletions. 相似文献
67.
Fluorescence resonance energy transfer detection of synaptophysin I and vesicle-associated membrane protein 2 interactions during exocytosis from single live synapses 总被引:3,自引:0,他引:3 下载免费PDF全文
Pennuto M Dunlap D Contestabile A Benfenati F Valtorta F 《Molecular biology of the cell》2002,13(8):2706-2717
To investigate the molecular interactions of synaptophysin I and vesicle-associated membrane protein 2 (VAMP2)/synaptobrevin II during exocytosis, we have used time-lapse videomicroscopy to measure fluorescence resonance energy transfer in live neurons. For this purpose, fluorescent protein variants fused to synaptophysin I or VAMP2 were expressed in rat hippocampal neurons. We show that synaptophysin I and VAMP2 form both homo- and hetero-oligomers on the synaptic vesicle membrane. When exocytosis is stimulated with alpha-latrotoxin, VAMP2 dissociates from synaptophysin I even in the absence of appreciable exocytosis, whereas synaptophysin I oligomers disassemble only upon incorporation of the vesicle with the plasma membrane. We propose that synaptophysin I has multiple roles in neurotransmitter release, regulating VAMP2 availability for the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex and possibly participating in the late steps of exocytosis. 相似文献
68.
Urocortin-deficient mice display normal stress-induced anxiety behavior and autonomic control but an impaired acoustic startle response 总被引:2,自引:0,他引:2 下载免费PDF全文
Wang X Su H Copenhagen LD Vaishnav S Pieri F Shope CD Brownell WE De Biasi M Paylor R Bradley A 《Molecular and cellular biology》2002,22(18):6605-6610
Corticotropin-releasing hormone (Crh) plays an important role in modulating physiological and behavioral responses to stress. Its actions are mediated through two receptors, Crhr1 and Crhr2. Urocortin (Ucn), a Crh-related neuropeptide and the postulated endogenous ligand for Crhr2, is a potential mediator of stress responses. We generated Ucn-deficient mice using embryonic stem cell technology to determine its role in stress-induced behavioral and autonomic responses. Unlike Crhr1- or Crhr2-deficient mice, Ucn-deficient mice exhibit normal anxiety-like behavior as well as autonomic regulation in response to stress. However, the mutant mice display an impaired acoustic startle response that is not due to an obvious hearing defect. Thus, our results suggest that Ucn does not play an essential role in stress-induced behavioral and autonomic responses. Ucn may modulate the acoustic startle response through the Ucn-expressing neuron projections from the region of the Edinger-Westphal nucleus. 相似文献
69.
Diorio LA Forchiassin F Papinutti VL Sueldo DV 《Revista iberoamericana de micología》2003,20(1):11-15
The ability to degrade organic solid wastes by the fungus Saccobolus saccoboloides was studied. The organism, unusual in such studies, was cultivated in synthetic liquid media with agitation, and on day 8 of growth the mycelium was passed to flasks with trimming. On day 16 of growth, the trimming degradation was assesed by carboxymethylcellulase, xylanase, and amylase activities evaluation, and NaOH 1% hydrolysis. Later on, the type of waste was modified (trimming, filter paper, newspaper, cardboard, sawdust and wood shaving were used) as well as the mass (300-1800 mg/flask). In these cases the enzymatic activities increased between 300 and 600 mg/flask. The total separation of the cellular components in all types of paper and cardboard was observed, together with a high loss of weight. S. saccoboloides was not able to degrade the wood wastes 相似文献
70.
Fomes sclerodermeus produces manganese peroxidase (MnP) and laccase as part of its ligninolytic system. A Doehlert experimental design was applied in order to find the optimum conditions for MnP and laccase production. The factors studied were Cu2+, Mn2+ and asparagine. The present model and data analysis allowed us not only to define optimal media for production of both laccase and MnP, but also to show the combined effects between the factors. MnP was strongly influenced by Mn2+, which acts as an inducer. Under these conditions Cu2+ negatively affected MnP activity. At 13 days of growth 0.75 U ml–1 were produced in the optimized culture medium supplemented with 1 mM MnSO4 and 4 g l–1 asparagine. The laccase titer under optimized conditions reached maximum values at 16 days of growth: 13.5 U ml–1 in the presence of 0.2 mM CuSO4, 0.4 mM MnSO4 and 6 g l–1 asparagine. Mn2+ promoted production of both enzymes. There were important interactions among the nutrients evaluated, the most significant being those between Cu2+ and asparagine. 相似文献