ACTOMYOSIN-LIKE PROTEIN IN BRAIN: SUBCELLULAR DISTRIBUTION

Abstract— An actomyosin-like protein (neurostenin) has been isolated from the synaptosomal fraction of bovine and rat brains. A similar protein could not be obtained from the mitochondrial, microsomal, myelin or supernatant fractions. The synaptosomal protein is a Mg²⁺ -Ca²⁺ -stimulated ATPase which exhibited the phenomenon of superprecipitation and viscosimetric sensitivity to ATP characteristic of actomyosins. It constituted 8–10 per cent of the total synaptosomal proteins. The protein could be dissociated into actin-like (neurin) and myosin-like (stenin) proteins by ultracentrifugation in sucrose gradients containing KI and ATP. The neurin, as well as muscle actin, stimulated the Mg²⁺ -ATPase activity of stenin and muscle myosin; the relative viscosities of the mixtures were increased and became sensitive to added ATP. The neurin contained 0.9 mol of 3-methylhistidine per 50,000 g of protein. The presence of these proteins in the synaptosomes suggests the possibility that they participate in nerve-ending functions, e.g. release of transmitter materials.     

应用电子探针研究黄叶生理病的水稻根内硅和铁分布

利用电子探针研究黄叶生理病的水稻根中一些元素的含量和分布,结果表明,硅和铁元素与稻叶发黄密切相关。通常稻根表皮层富集铁而内皮层富集硅,生理失调稻根表皮层中的铁远高于正常稻,而内皮层中的硅则较少。发病稻根高铁低硅的特征为深入研究发病的机理和土壤条件提供了线索。