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71.
The Raman and infrared spectra of poly(L -lysine) and poly(DL -lysine) in solution are reported and the effects of various salts are investigated. The results demonstrate that α-helix formation in solution is induced by specific salts and the spectral data support the hypothesis of regions of local order for poly(L -lysine) in aqueous solutions of low ionic strength. 相似文献
72.
Ascorbate caused a dose-dependent increase in sister-chromatid exchanges (SCEs) in Chinese hamster ovary (CHO) cells and in human lymphocytes. Moreover, in the DNA synthesis inhibition test with HeLa cells, ascorbate gave results typical of DNA-damaging chemicals. Catalase reduced SCE induction by ascorbate, prevented its cytotoxicity in CHO cells, and prevented its effect on HeLa DNA synthesis. Ascorbate reduced induction of SCE in CHO cells by N-methylN′-nitrosoguanidine (MNNG) by direct inactivation of MNNG. 相似文献
73.
74.
Kevin J. Painter 《Theoretical Ecology》2014,7(1):53-75
Hilltopping butterflies direct their movement in response to topography, facilitating mating encounters via accumulation at summits. In this paper, we take hilltopping as a case study to explore the impact of complex orienteering cues on population dynamics. The modelling employs a standard multiscale framework, in which an individual’s movement path is described as a stochastic ‘velocity-jump’ process and scaling applied to generate a macroscopic model capable of simulating large populations in landscapes. In this manner, the terms and parameters of the macroscopic model directly relate to statistical inputs of the individual-level model (mean speeds, turning rates and turning distributions). Applied to hilltopping in butterflies, we demonstrate how hilltopping acts to aggregate populations at summits, optimising mating for low-density species. However, for abundant populations, hilltopping is not only less effective but also possibly disadvantageous, with hilltopping males recording a lower mating rate than their non-hilltopping competitors. 相似文献
75.
N. S. Painter 《BMJ (Clinical research ed.)》1968,3(5616):475-479
76.
77.
Comparative immunology: natural hemolytic system of the spiny lobster, Panulirus argus 总被引:2,自引:0,他引:2
78.
Robert B. Painter 《The Journal of cell biology》1961,11(2):485-488
79.
Carrier-independent entry of 1-methyl-4-phenylpyridinium (MPP+) into adrenal chromaffin cells as a consequence of charge delocalization 总被引:3,自引:0,他引:3
J F Reinhard A J Daniels G R Painter 《Biochemical and biophysical research communications》1990,168(3):1143-1148
The administration of 1-methyl-4-phenylpyridinium (MPP+) to cultures of adrenal medullary chromaffin cells resulted in time and concentration-dependent increases in the cellular content of MPP+. Co-incubation of cells with MPP+, in the presence of desmethylimipramine (DMI), reduced but did not prevent the accumulation of the pyridinium in these cells. Similarly, DMI and MPP+ co-administration reduced but did not prevent the neurotoxicant-induced release of a cytosolic marker, lactate dehydrogenase, into the media. Molecular orbital calculations reveal that the positive charge of MPP+ is highly delocalized throughout the pyridinium ring and consequently MPP+ may be able to diffuse down concentration or charge gradients. Thus, these data provide a basis for the entry of MPP+ into cells and subcellular organelles that lack a catecholamine transporter, e.g. mitochondria. 相似文献
80.