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1.
Steven J. Tucker David McClelland Kristina Sep?i? Roderick H. Scott 《生物化学与生物物理学报:生物膜》2003,1614(2):171-181
The ability of two alkyl pyridinium sponge toxin preparations (poly-APS and halitoxin) to form transient pores/lesions in cell membranes and allow transfection of plasmid cDNA have been investigated using HEK 293 cells. Poly-APS and halitoxin preparations caused a collapse in membrane potential, reductions in input resistance and increased Ca2+ permeability. At least partial recovery was observed after poly-APS application but recovery was more rarely seen with halitoxin. The transfection with plasmid cDNAs for an enhanced green fluorescent protein (EGFP) and human tumour necrosis factor receptor 2 (TNFR2) was assessed for both toxin preparations and compared with lipofectamine. Stable transfection was achieved with poly-APS although it was less efficient than lipofectamine. These results show that viable cells transfected with alien cDNA can be obtained using novel transient pore-forming alkyl pyridinium sponge toxins and a simple pre-incubation protocol. This provides the first proof of principle that pore-forming alkyl pyridinium compounds can be used to deliver cDNA to the intracellular environment without permanently compromising the plasma membrane. 相似文献
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Symplastic Transport of Carboxyfluorescein in Staminal Hairs of Setcreasea purpurea Is Diffusive and Includes Loss to the Vacuole 总被引:8,自引:4,他引:4 下载免费PDF全文
The kinetics of symplastic transport in staminal hairs of Setcreasea purpurea was studied. The tip cell of a staminal hair was microinjected with carboxyfluorescein (CF) and the symplastic transport of this CF was videotaped and the digital data analyzed to produce kinetic curves. Using a finite difference equation for diffusion between cells and for loss of dye into the vacuole, kinetic curves were calculated and fitted to the observed data. These curves were matched with data from actual microinjection experiments by adjusting K (the coefficient of intercellular junction diffusion) and L (the coefficient of intracellular loss) until a minimum in the least squares difference between the curves was obtained. (a) Symplastic transport of CF was governed by diffusion through intercellular pores (plasmodesmata) and intracellular loss. Diffusion within the cell cytoplasm was never limiting. (b) Each cell and its plasmodesmata must be considered as its own diffusion system. Therefore, a diffusion coefficient cannot be calculated for an entire chain of cells. (c) The movement through plasmodesmata in either direction was the same since the data are fit by a diffusion equation. (d) Diffusion through the intercellular pores was estimated to be slower than diffusion through similar pores filled with water. 相似文献
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W N Henley L L Bellush A Tucker 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1989,192(2):114-120
Exposure to hypobaric hypoxia (H; simulated altitude = 3658 m) was initiated in 5-week-old, male spontaneously hypertensive (SHR) and Wistar-Kyoto (WKy) normotensive rats while normoxic controls (N) for both groups were maintained under laboratory conditions. Significant attenuation of systolic arterial blood pressure was evident in SHR-H relative to SHR-N (125 +/- 6 vs 145 +/- 5 mm Hg; P less than 0.05) but not in WKy-H relative to WKy-N (WKy-H, 116 +/- 2 vs WKy-N, 117 +/- 5 mm Hg). Hypoxia significantly decreased metabolic efficiency in both normotensive and hypertensive rats, although being both more severe and accompanied by significantly impaired growth rate in SHR-H. Urinary excretion of norepinephrine in the SHR was elevated relative to WKy, irrespective of altitude treatment, while hypoxia elicited similar increases in urinary excretion of norepinephrine in both SHR and WKy. Myocardial and adrenal contents of norepinephrine were significantly reduced following 3 days of simulated altitude exposure in both strains of rats. Tissue contents of norepinephrine in hypoxic rats returned to normoxic levels by 21 days of simulated altitude. Both urine and tissue indices provided consistent indirect evidence that changes in sympathetic neuronal activity in response to hypoxia were similar in normotensive and hypertensive rats. These findings suggest that prior reports of reduced alpha-adrenergic responsiveness in vasculature from hypoxia-exposed SHR reflect a postsynaptic event that is regulated independently of norepinephrine release from sympathetic nerve terminals. 相似文献
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Reactive amyloidosis occurs during chronic inflammation and involves deposition of amyloid A (AA) fibrils in many organs. Amyloid A is derived by proteolysis from serum amyloid A component (SAA), a major acute-phase reactant in many species. Since spontaneous amyloidosis occurs commonly in Syrian hamsters, we have studied the structure and expression of SAA genes during inflammation in these animals. Two cDNA clones and one genomic clone were sequenced, suggesting that Syrian hamster SAA is encoded by at least two genes. Hepatic mRNA analyses showed that SAA was inducible in many hamster organs during acute inflammation. These studies also demonstrated that SAA mRNA for one isotype is maximally expressed at a site of local tissue damage. 相似文献
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Seasonal and spatial variations in the zooplankton community of an Eastern Antarctic coastal location 总被引:3,自引:3,他引:0
Summary The zooplankton community of a shallow coastal area in Eastern Antarctica was found to be one of low species diversity dominated by Copepoda. It was comprised of the more common Antarctic oceanic copepod species, medusae, molluscs, euphausiids, several copepod species associated with the ice-water interface and, in summer, benthic fauna larvae. Most species of copepods displayed a marked seasonality in abundance with peak numbers between March and May. It is proposed that several factors, including phytoplankton seasonality contribute to the zooplankton species composition, zooplankton seasonality, and to the temporal differences in the period of maximum abundance between copepod species. Annual vertical migratory behaviour in conjunction with the circulation of Prydz Bay are important determining factors for those species which can be considered as oceanic; Calanoides acutus, Calanus propinquus, Ctenocalanus citer, Metridia gerlachei, Oithona similis and Oncaea curvata. However, for copepod species which can be classified as inshore residents, such as Stephos longipes, Paralabidocera antarctica and Drepanopus bispinosus, it is their association with the ice water interface that determines their seasonal appearance and abundance. Some differences were established between the zooplankton community of the Vestfold Hills and that of other Antarctic coastal regions. This may be attributed, in part, to the extensive shallow areas of the Vestfold Hills coastal region. Spatial distribution of the zooplankton with depth and between sites was investigated and found to be essentially homogenous. When differences were established, in the majority of cases all species present, all age classes and both sexes contributed to the differences. 相似文献
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Hydrophobic pulmonary surfactant protein enriched in SP-C has been mixed in amounts up to 10% by weight with various phospholipids. The lipids used were dipalmitoyl phosphatidylcholine (DPPC), or DPPC plus unsaturated phosphatidylglycerol (PG), or phosphatidylinositol (PI) in molar ratios of 9:1 and 7:3. The protein enhanced the rate and extent of adsorption of each lipid preparation into the air-water interface, and its respreading after compression on a surface balance. Maximum surface pressures attained on compression of monolayers of mixtures of lipids were slightly higher in the presence of protein. The effects on rate and extent of adsorption were proportional to the amount of protein present. Mixtures containing 30 mol% PG or PI adsorbed more readily into the interface than those containing 10% acidic lipid or DPPC alone. Mixtures containing 30% PI were slightly more rapidly adsorbed than those containing 30% PG. The results suggest that mixtures of DPPC with either acidic lipid in the presence of surfactant protein could be effective in artificial surfactants. 相似文献