A systematic effort was made to elucidate the mode of recognition at the inositol 1,4,5-trisphosphate-specific receptor. Eleven D-myo-inositol phosphates were synthesized and tested for ...Ca(2+)-mobilizing and receptor-binding activities, which included Ins(1,3,4,5,6)P5, Ins(1,2,5,6)P4, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(3,4,5,6)P4, Ins(1,3,4)P4, Ins(1,4,5)P3, Ins(1,5,6)P3, Ins(1,4)P2, and Ins(4,5)P2. Of these, Ins(1,4,5)P3, Ins(1,3,4,6)P4, Ins(1,3,4,5)P4, Ins(1,4,5,6)P4, and Ins(4,5)P2 were able to elicit Ca2+ release from rat brain microsomes. Binding experiments suggest that the ability of these polyphosphates to effect Ca2+ mobilization arises from interactions with the Ins(1,4,5)P3-specific receptor. Accordingly, a model accounting for the ligand recognition is proposed. The Ins(1,4,5)P3-binding site is presumably composed of two domains. The anchoring domain binds the 4,5-bisphosphate 6-hydroxy motif. Disruption of this structural feature abolishes the agonist activity. The auxiliary domain exerts long-range interactions with the 1-phosphate, thus enhancing the binding affinity. The stereochemical requirement for this electrostatic interaction is, however, less stringent. Evidence suggests that Ca(2+)-mobilizing inositol phosphates are able to effect productive binding by assuming conformations displaying or mimicking these essential structural features.
Modification of ZnO films under high energy Xe-ion irradiations Zang, H.; Wang, Z.G.; Peng, X.P. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
June 2008, 2008-06-00, Letnik:
266, Številka:
12-13
Journal Article
Recenzirano
ZnO films were deposited on (100) Si substrate by radio frequency magnetron sputtering. These films were irradiated at room temperature with 308MeV Xe-ions to a fluence of 1.0×1012, 1.0×1013 or ...1.0×1014Xe/cm2. Then the samples were investigated using RBS, XRD, FESEM and PL analyses. The obtained experimental results showed that the deposited ZnO films were highly c-axis orientated and of high purity, 308MeV Xe-ion irradiations could not change the c-axis oriented. The topography and PL properties of the ZnO films varied with increasing the Xe-ion irradiation fluence. For 1.0×1013 or 1.0×1014Xe/cm2 irradiated samples, surface cracks were observed. Furthermore, it was found that the 1.0×1014Xe/cm2 irradiated sample exhibiting the strongest PL ability. The modification of structure and PL properties induced by 308MeV Xe-ion irradiations were briefly discussed.
To assess the genetic diversity between randomly and selectively bred populations, we sequenced 438 bp of the mitochondrial DNA control region from 102 pigs. These samples represented four native pig ...breeds, one nucleus and one conservation herd from Yunnan, China. Twenty haplotypes with sixteen polymorphic sites were identified. The number of haplotypes in the nucleus herd of Saba pig and the conservation herd of Banna miniature pig were restricted to three and one, respectively, while the randomly bred pig populations exhibited over six haplotypes. Notably, haplotype diversity in randomly bred populations was significantly greater than the selectively bred populations (h=0.732 vs. 0.425 and 0, exact test, P<=0.0036). These findings demonstrate that selective breeding generated low genetic diversity compared to randomly bred pig breeds. A timely intervention and well programmed breeding approach would stop further genetic diversity reduction in the nucleus and conservation herds of native pig breeds. Otherwise, selective breeding would dramatically reduce genetic diversity in only several years, indicating that sharp contradictions exist between breeding, conservation and genetic diversity. Genetic relationships are discussed based on net genetic distances among pig populations.
This report documents the formation of stable fetal cardiomyocyte grafts in the myocardium of dystrophic dogs. Preliminary experiments established that the dystrophin gene product could be used to ...follow the fate of engrafted cardiomyocytes in dystrophic mdx mice. Importantly, ultrastructural analyses revealed the presence of intercalated discs consisting of fascia adherens, desmosomes, and gap junctions at the donor-host cardiomyocyte border. To determine if isolated cardiomyocytes could form stable intracardiac grafts in a larger species, preparations of dissociated fetal canine cardiomyocytes were delivered into the hearts of adult CXMD (canine X-linked muscular dystrophy) dogs. CXMD dogs, like Duchenne muscular dystrophy patients and mdx mice, fail to express dystrophin in both cardiac and skeletal muscle. Engrafted fetal cardiomyocytes, identified by virtue of dystrophin immunoreactivity, were observed to be tightly juxtaposed with host cardiomyocytes as long as 10 wk after engraftment, the latest date analyzed. Confocal laser scanning microscopy revealed the presence of connexin43, a major constituent of the gap junction, at the donor-host cardiomyocyte border. The presence of intracardiac grafts was not associated with arrhythmogenesis in the CXMD model. These results indicate that fetal cardiomyocyte grafting can successfully augment cardiomyocyte number in larger animals.
In a search for new partners of the activated form of Rac GTPase, we have isolated through a two-hybrid cloning procedure a human cDNA encoding a new GTPase-activating protein (GAP) for Rho family ...GTPases. A specific mRNA of 3.2 kilobases was detected in low abundance in many cell types and found highly expressed in testis. A protein of the predicted size 58 kDa, which we call MgcRacGAP, was detected in human testis as well as in germ cell tumor extracts by immunoblotting with antibodies specific to recombinant protein. In vitro, the GAP domain of MgcRacGAP strongly stimulates Rac1 and Cdc42 GTPase activity but is almost inactive on RhoA. N-terminal to its GAP domain, MgcRacGAP contains a cysteine-rich zinc finger-like motif characteristic of the Chimaerin family of RhoGAPs. The closest homolog of MgcRacGAP is RotundRacGAP, a product of the Drosophila rotund locus. In situ hybridization experiments in human testis demonstrate a specific expression of mgcRacGAP mRNA in spermatocytes similar to that of rotundRacGAP in Drosophila testis. Therefore, protein sequence similarity and analogous developmental and tissue specificities of gene expression support the hypothesis that RotundRacGAP and MgcRacGAP have equivalent functions in insect and mammalian germ cells. Since rotundRacGAP deletion leads to male sterility in the fruit fly, the mgcRacGAP gene may prove likewise to play a key role in mammalian male fertility.
A series of nonpeptide somatostatin agonists which bind selectively and with high affinity to somatostatin receptor subtype 2 (sst2) have been synthesized. One of these compounds, L-054,522, binds to ...human sst2 with an apparent dissociation constant of 0.01 nM and at least 3,000-fold selectivity when evaluated against the other somatostatin receptors. L-054,522 is a full agonist based on its inhibition of forskolin-stimulated adenylate cyclase activity in Chinese hamster ovary-K1 cells stably expressing sst2. L-054,522 has a potent inhibitory effect on growth hormone release from rat primary pituitary cells and glucagon release from isolated mouse pancreatic islets. Intravenous infusion of L-054,522 to rats at 50 μ g/kg per hr causes a rapid and sustained reduction in growth hormone to basal levels. The high potency and selectivity of L-054,522 for sst2 will make it a useful tool to further characterize the physiological functions of this receptor subtype.
In this paper, molecular dynamics simulations were performed to study interactions between atomic H and SiC, silicon carbon surfaces were continuously bombarded by atomic H with different energies. ...The Tersoff-Brenner potentials were implemented. The simulation results show that with increasing incident energy, the retention rate of H atoms on the surface increases linerly. A large number of H atoms depositing on the surface results in the forming of Si,C and H layer on the surface and with increasing incident energy, H atoms penetrate deeper into the substrate, the thickness of the layer increases. The products H, H2 and SiH4 are dominant among the sputtering products, the number of H, H2 is much more than SiH4. And products are also different at different energies.
The alkoxide sol–gel synthesis of nanostructured TiO2 has been studied systematically to examine the processing parameters that control crystallite size and phase. A hydrothermal method has been ...proposed to prepare uniform and unaggregated nanocrystals of pure anatase in nitric acidic medium. Hydrolysis and polycondensation of titanium n-butoxide (Ti(OC4H9)4) have been performed in the presence of polyethylene glycol (PEG). The use of polyethylene glycol (PEG) and the effect of its concentrations on the formation of anatase phase have been described in detail using X-ray diffraction and transmission electron microscopy. It was found that nanocrystalline anatase particle (<10 nm) was derived by hydrothermal processing at 160 °C for 5 h.
PDF
