Single cell selection

Microelectrodes can be made sufficiently small to measure intracellular ion activities, as shown schematically in Fig. 5 The micro ion-selective electrode is inserted into a single cell by means of a micromanipulator. The intracellular activity of the... 

Walker, J. L. Single Cell Measurement with Ion-Selective Electrodes, in Medical and Biological Applications of Electrochemical Devices (Koryta, J., ed.) New York, Wiley, 1980, p. 109... 

A single cell layer of an excised piece of onion epidermis was selected as a test object for this micro-coil, (Figure 2.1.14), and an imaging experiment was carried out, similar to the one by Mansfield et al., who used a laboratory-made micro-coil probe and gradient system [31]. Other micro-coil types, e.g., volume coils or coils that are immersed into the objects, can be adapted to specific applications and mounted on commercial imaging probes. 

A core assumption of ultra-Darwinism is that if not all, then most observed characters must be adaptive, so as to provide the phenotypic material upon which natural selection can act. However, what constitutes a character - and what constitutes an adaptation - is as much in the eye of the beholder as in the organism that is beheld, as Gould and Lewontin pointed out in their famous paper on spandrels (Gould and Lewontin, 1979). Natural selection s continual scrutiny does not give it an a la carte freedom to accept or reject genotypic or phenotypic variation. Structural constraints insist that evolutionary, genetic mechanisms are not infinitely flexible but must work within the limits of what is physically or chemically possible (for instance, the limits to the size of a single cell occasioned by the physics of diffusion processes, the size of a crustacean like a lobster or crab by the constraints... 

Because of the importance of ATP in these mechanisms, the BL system was used as standard procedure for an extremely sensitive and selective determination of the cited molecule. The detection limit for the firefly assay method is about l(Tn mol/L ATP, allowing the detection of single cells in certain cases... 

Signal transduction now ensures that information is selectively addressed to single cell types, where it is registered and transformed in a common manner - e. g., in the case of a human being which is composed of some trillions of cells [1]. Hereby metabolic fluxes or cell division are controlled efficiently. 

Reymond O, Pickett-Heaps J. A routine flat embedding method for electron microscopy of microorganisms allowing selection and precisely oriented sectioning of single cells by light microscopy. J Microsc 1983 130 79-84. 

The electrolysis apparatus for the polymerization is illustrated in Figure 2, which is characterized by a single cell without a partition membrane between the electrodes. In poor solvents of poly(phenyleneoxide) s such as methanol and acetonitrile, the polymer was deposited on the electrode, i.e. passivation of the electrode occured. Dichlo-romethane, nitrobenzene, and hydroquinone dimethyl ether were selected as the solvents because both the polymer and a supporting electrolyte dissolved in them and they were relatively stable under electrolysis conditions. 

At the same time, all cells are unified at the molecular level, as emphasized in the first chapter. There are other commonalities as well. All cells have a plasma membrane that surrounds and encloses them. The fundamental function of the plasma membrane is to act as a selective barrier between the cell interior and the external environment. In the Eubacteria and Archaea, single cell organisms all, the plasma membrane is the sole membrane of the cell. In contrast, in the Eukarya, there are a variety... 

J. L. Walker, Single cell measurement with the lon-selective electrodes. Chapter 4... 

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