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51.
52.
The subcellular fractionation of embryonic chick tendon and cartilage cells: a re-examination. 下载免费PDF全文
A re-examination of the subcellular fractions obtained from matrix-free chick tendon and cartilage cells has been made since the discovery that three out of four of the micrographs of chick tendon microsomal fractions published in an earlier paper from this laboratory were not authentic. The present studies demonstrate that by using the procedures previously reported it is possible to isolate microsomal and submicrosomal fractions from tendon and cartilage cells which exhibit typical morphology when examined by electron microscopy. These observations are consistent with our original biochemical characterization of subcellular fractions, which we know to be valid. Other publications from this laboratory in which these fractionation procedures have been applied to studies of collagen biosynthesis are in no way compromised, and indeed, most of our data have been confirmed by several other laboratories. 相似文献
53.
I F Williams R Harwood M E Grant 《Biochemical and biophysical research communications》1976,70(1):200-206
White erythrocyte membranes, or ghosts, were monoconcave discocytes when incubated in 50mM N-tris (hydroxymethyl) methyl-2-aminoethane sulfonic acid titrated to pH 7.4 with triethanolamine. If 3mM MgCl2 was included in the incubation medium, the ghosts were predominantly echinocytes. The echinocytic form could also be induced by Co++, Ni++, Li+, Na+, K+, and tetramethylammonium ion, all as chloride salts. The concentration of cation necessary for 50% of the ghosts to be echinocytes was correlated with the hydrated charge density of the cation with the most highly charged cations being the most effective. The cations Ca++, Sr++, Ba++ and La+++, (also as chloride salts) did not induce the normal echinocytic form, but at high levels induced a few misshapen forms with some resemblance to echinocytes. Instead Ca++, Sr++, Ba++ and La+++ suppressed the formation of echinocytes in the presence of Mg++ and other ions. This suggests the presence of a specific Ca++ binding site important to shape control in the erythrocyte membrane. 相似文献
54.
In December 1968 an emergency service was set up in Edinburgh to enable patients with severe asthma to be admitted to hospital without delay. Up to 31 August 1975, 82 such patients had been admitted on 162 occasions, on 116 without the intervention of a general practitioner. The service is extended to patients particularly at risk of developing fatal asthma, and since it began no patient has died from asthma outside hospital. One patient, however, died from tension pneumothorax that developed after admission. We believe that similar services should be available throughout Britain. 相似文献
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Partial characterization of type X collagen from bovine growth-plate cartilage. Evidence that type X collagen is processed in vivo 总被引:1,自引:0,他引:1
Sequential extraction of bovine growth-plate cartilage with 4 M guanidinium chloride and pepsin was used to identify the intact and pepsinized forms respectively of type X collagen. This collagen occurs predominantly as the processed [alpha 1(X)]3 form in vivo, although the procollagen [pro alpha 1(X)]3 form can also be detected. The bovine pro alpha 1(X) and alpha 1(X) chains have Mr values identical to the corresponding chick species (Mr 59,000 and 49,000). However, the pepsinized alpha 1(X)p chains (Mr 47,000) are larger than those of the chick (Mr 45,000), and the bovine collagen type X is further distinguished by being disulphide-bonded within the triple-helical domain. 相似文献
57.
Anthony P. Grant 《The journal of the Royal Anthropological Institute》2020,26(4):901-902
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Sex expression in the dioecious plant white campion (Silene latifolia Poiret subsp. alba) appears to be insensitive to exogenous applications of auxins, cytokinins, gibberellic acid, and ethylene; however, silver thiosulfate (Ag(2)S(2)O(3)), an ethylene inhibitor, enhanced stamen development in female white campion. In wild-type females, stamen development is arrested before the microspore mother cells are formed. In contrast, stamens of Ag(2)S(2)O(3)-treated females completed meiosis and produced microspores. Stamen development for these females was incomplete, however, and pollen did not mature. Ag(2)S(2)O(3) stimulated stamen development to the same extent in asexual white campion mutants that retained a Y chromosome but had lost Y-linked genes needed for early stages of stamen development. Although Ag(2)S(2)O(3) can inhibit ethylene signaling, the enhancement of stamen development in female white campion cannot be explained as a loss of ethylene response because no other ethylene inhibitor tested (1-methylcyclopropene, trans-cyclooctene, aminoethoxyvinylglycine, and cobalt chloride) caused stamens to develop in female plants. In addition, application of other metal ions could not enhance stamen development. Therefore, the effect we observed on female white campion was specifically caused by silver ions but not by their action on ethylene signaling. 相似文献
59.
Vitaly V. Vostrikov Christopher V. Grant Stanley J. Opella Roger E. Koeppe II 《Biophysical journal》2011,101(12):2939
The dynamics of membrane-spanning peptides have a strong affect on the solid-state NMR observables. We present a combined analysis of 2H-alanine quadrupolar splittings together with 15N/1H dipolar couplings and 15N chemical shifts, using two models to treat the dynamics, for the systematic evaluation of transmembrane peptides based on the GWALP23 sequence (acetyl-GGALW(LA)6LWLAGA-amide). The results indicate that derivatives of GWALP23 incorporating diverse guest residues adopt a range of apparent tilt angles that span 5°–35° in lipid bilayer membranes. By comparing individual and combined analyses of specifically 2H- or 15N-labeled peptides incorporated in magnetically or mechanically aligned lipid bilayers, we examine the influence of data-set size/identity, and of explicitly modeled dynamics, on the deduced average orientations of the peptides. We conclude that peptides with small apparent tilt values (<∼10°) can be fitted by extensive families of solutions, which can be narrowed by incorporating additional 15N as well as 2H restraints. Conversely, peptides exhibiting larger tilt angles display more narrow distributions of tilt and rotation that can be fitted using smaller sets of experimental constraints or even with 2H or 15N data alone. Importantly, for peptides that tilt significantly more than 10° from the bilayer-normal, the contribution from rigid body dynamics can be approximated by a principal order parameter. 相似文献
60.