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981.
Renata Hordejuk Nikolai A. Lobanov Anna Kicinska Krzysztof Dolowy 《Molecular membrane biology》2013,30(5):307-313
We report here that large conductance K+ selective channel in adrenal chromaffin granules is controlled by pH. We measured electrogenic influx of 86Rb+ into chromaffin granules prepared from bovine adrenal gland medulla. The 86Rb+ influx was inhibited by acidic pH. Purified chromaffin granule membranes were also fused with planar lipid bilayer. A potassium channel with conductance of 432±9 pS in symmetric 450 mM KCl was observed after reconstitution into lipid bilayer. The channel activity was unaffected by charybdotoxin, a blocker of the Ca2+-activated K+ channel of large conductance. It was observed that acidification to pH 6.4 cis side of the membrane lowered the channel open probability and single channel conductance. Whereas only weak influence on the single channel current amplitude and open probability were observed upon lowering of the pH at the trans side. We conclude that a pH-sensitive large conductance potassium channel operates in the chromaffin granule membrane. 相似文献
982.
F. Houben W. H. De Vos I. P. C. Krapels M. Coorens G. J. J. Kierkels M. A. F. Kamps V. L. R. M. Verstraeten C. L. M. Marcelis A. van den Wijngaard F. C. S. Ramaekers J. L. V. Broers 《Histochemistry and cell biology》2013,139(1):119-134
There is growing evidence that laminopathies, diseases associated with mutations in the LMNA gene, are caused by a combination of mechanical and gene regulatory distortions. Strikingly, there is a large variability in disease symptoms between individual patients carrying an identical LMNA mutation. This is why classical genetic screens for mutations appear to have limited predictive value for disease development. Recently, the widespread occurrence of repetitive nuclear ruptures has been described in fibroblast cultures from various laminopathy patients. Since this phenomenon was strongly correlated with disease severity, the identification of biomarkers that report on these rupture events could have diagnostic relevance. One such candidate marker is the PML nuclear body, a structure that is normally confined to the nuclear interior, but leaks out of the nucleus upon nuclear rupture. Here, we show that a variety of laminopathies shows the presence of these cytoplasmic PML particles (PML CPs), and that the amount of these protein aggregates increases with severity of the disease. In addition, between clinically healthy individuals, carrying LMNA mutations, significant differences can be found. Therefore, we postulate that detection of PML CPs in patient fibroblasts could become a valuable marker for diagnosis of disease development. 相似文献
983.
Nikolai M. Veter Larisa R. G. DeSantis Lindsey T. Yann Shelly L. Donohue Ryan J. Haupt Sarah E. Corapi Siobhan L. Fathel Emily K. Gootee Lucas F. Loffredo Jennifer L. Romer Stoycho M. Velkovsky 《Biology letters》2013,9(5)
Macroecology strives to identify ecological patterns on broad spatial and temporal scales. One such pattern, Rapoport''s rule, describes the tendency of species'' latitudinal ranges to increase with increasing latitude. Several mechanisms have been proposed to explain this rule. Some invoke climate, either through glaciation driving differential extinction of northern species or through increased seasonal variability at higher latitudes causing higher thermal tolerances and subsequently larger ranges. Alternatively, continental tapering or higher interspecific competition at lower latitudes may be responsible. Assessing the incidence of Rapoport''s rule through deep time can help to distinguish between competing explanations. Using fossil occurrence data from the Palaeobiology Database, we test these hypotheses by evaluating mammalian compliance with the rule throughout the Caenozoic of North America. Adherence to Rapoport''s rule primarily coincides with periods of intense cooling and increased seasonality, suggesting that extinctions caused by changing climate may have played an important role in erecting the latitudinal gradients in range sizes seen today. 相似文献
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Noah M Ivers Jacqueline Young Jill J Francis Jan Barnsley Baiju R Shah Ross E Upshur Jeremy M Grimshaw Merrick Zwarenstein 《Implementation science : IS》2013,8(1):142