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111.
Technical advance: an automated device for cryofixation of specimens of electron microscopy using liquid helium 总被引:2,自引:0,他引:2
Metal-contact rapid freezing using liquid helium is theoretically the best method for preserving the fine structure of living cells with high temporal resolution in preparation of tissue samples for electron microscopy. However, this method is not commonly used, because of its technical difficulty and low reproducibility. We have designed and constructed an automatic device which allows simple, rapid and reproducible preparation of high-quality electron microscopic specimens by the non-specialist. We assessed the quality of cryofixation in samples prepared using this device by examining the preservation of cellular ultrastructure in relation to distance from the freezing block, and found that the region within 10 microm of the metal-contact plane was fixed with the highest quality. We applied this device, in combination with freeze-substitution methods and immunocytochemical techniques, to two phenomena involving rapid movement of subcellular components: (1) active movement of subcellular structures in the papillar cells of stigma and (2) light-induced rapid subcellular translocation of phytochrome A. Considering the importance of understanding subcellular processes of living cells for molecular and cell biology, this device will be a useful tool for diverse biological applications in the near future. 相似文献
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Masami Yoshino Masakazu Takahata Mituhiko Hisada 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1982,145(4):471-476
Summary Rolling of the body in the same direction induces an asymmetrical steering movement of uropods in the opposite directions in two closely related species of crayfish. InProcambarus clarkii the uropod on the upper side is spread out and closed on the lower side, whereas inCambaroides japonicus the uropod moves in the opposite direction. The stimulus detector, the statocysts, the effector, the uropod musculature, are neither structurally nor functionally significantly different in the two species. The results indicate that the opposite responses could be ascribed to differences in the interneuronal connections within the central nervous system of these two species. 相似文献
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M Yoshino K Masuda M Hisada 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1984,78(2):295-300
The effects of acetylcholine (ACh), carbamylcholine and gamma-aminobutyric acid (GABA) on the spike activity of uropod motoneurons were investigated electrophysiologically in the crayfish Procambarus clarkii Girard and Cambaroides japonicus de Haan. High concentrations of ACh were required to bring about an increase in the spike discharge of uropod motoneurons while carbamylcholine, which is not destroyed by cholinesterase, caused a marked increase in the motoneuron spike discharge even in low concentrations. Application of GABA in concentrations of 10(-5)-10(-2) M caused the decrease in the spike discharge of uropod motoneurons. Under the condition that the synaptic transmission onto uropod motoneurons was blocked by perfusing EGTA containing Ca2+-free saline with high-Mg2+, ACh increased the spike discharge of uropod motoneurons whereas GABA decreased it. The results suggested that ACh and GABA function as excitatory and inhibitory transmitters, respectively, in the crayfish central nervous system. 相似文献
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The effects of some putative transmitters and biogenic amines were examined on the uropod ventral abductor exopodite (AbdExV) muscle in two crayfish species Procambarus clarkii and Cambaroides japonicus. Bath application of L-glutamate to the AbdExV muscle caused sustained contract while gamma-aminobutyric acid (GABA) depressed the nerve-evoked contraction of the muscle. Acetylcholine (ACh) had no effect on both the resting tension and the nerve-evoked contraction. Iontophoresis of L-glutamate and GABA onto the surface of the muscle fiber further confirmed that glutamate and GABA are the possible excitatory and inhibitory transmitters respectively at the neuromuscular junction of AbdExV muscle. Bath application of 5-hydroxytryptamine (5-HT) and octopamine (Oct) caused enhancement of the nerve-evoked contraction but dopamine (DA) had no effect on both the resting tension and the nerve-evoked contraction. 相似文献
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This paper describes the properties and application of 1-methoxy-5-methylphenazinium methyl sulfate (1-methoxyPMS), which is a photochemically stable, versatile electron carrier. Like 5-methylphenazinium methyl sulfate (PMS), it mediates electron transfer between NADH and various electron acceptors such as tetrazolium dyes or the electrode of an enzymic electric cell, and yet it does not deteriorate upon storage under scattered light in normal laboratories. The rate of reduction of 1-methoxyPMS coupled to the reoxidation of NADH produced by the lactate dehydrogenase reaction, was even faster than that of PMS. It was also successfully employed as an electron mediator in the enzymic electric cell method for the assay of NAD-linked dehydrogenases. 1-MethoxyPMS solution is rosy pink, and its standard redox potential (E0') is approximately +0.063 V. The use of 1-methoxyPMS will be beneficial in biochemistry as well as medical technology, where PMS has been used as an electron mediator in various electron transfer systems. 相似文献