Electric organ

Viewing things from the perspective of his physical theory of contact electricity, Volta was intrigued by the apparently endless power of the battery to keep the electric fluid in motion without the mechanical actions needed to operate the classical, friction, electrostatic machine, and the electrophorus. He called his batteiy alternately the artificial electric organ, in homage to the torpedo fish that had supplied the idea, and the electromotive apparatus, alluding to the perpetual motion (his words) of the electric fluid achieved by the machine. To explain that motion Volta relied, rather than on the concepts of energy available around 1800, on his own notion of electric tension. He occasionally defined tension as the effort each point of an electrified body makes to get rid of its electricity but above all he confidently and consistently measured it with the electrometer. 

In the electric organ of fishes, a number of such stacks are connected in parallel and in series. The total voltage attains 500 V in the electric eel. A current pulse of about 0.5 A develops when this voltage appears across an external circuit (in fresh water or seawater). For the electric ray, these numbers are 60 V and 50 A, respectively. The length of such an electric pulse is comparable with the time of cell membrane excitation (i.e., 1 to 2ms, which is quite sufficient to defeat a designated victim). Some species of fish use pulses repeated at certain intervals. 

Harris, W.E. and Stahl, W.L. (1980). Oiganisation of thiol groups of electric eel electric organ Na/K ion stimulated adenosine triphosphatase, studied with bifunctional reagents. Biochem. J. 185, 787-790. 

The acetylcholine receptor (AChR) of Torpedo electric organ is also a PCP "receptor." However, this nicotinic AChR has about one-tenth the affinity for PCP than that of the rat brain PCP receptor [K0.5 = 0.3 pM, versus = 4-6 pM for Torpedo (Heidmann et al. 1983 flaring et al. 1984)]. Moreover, the nicotinic AChR has subunits of MR<66 kD, and these are the subunits that are specifically labelled with 3H-Az-PCP in the Torpedo electroplax membranes (Heidmann et al. 1983 Haring and Kloog 1984 Haring et al. 1984). These data indicate that the nicotinic AChR-PCP receptor differs from the rat brain PCP receptor. Furthermore, our findings are... 

Haring, R., and Kloog, Y. Multiple binding sites for phencyclidine on the nicotinic acetylcholine receptor from Torpedo ocel -lata electric organ. I ife Sci 34 1047-1055, 1984. 

Caenorhabditis elegans is a soil nematode that has been subjected to detailed genetic analysis. The possible structure of the nematode levamisole receptor, based on the pentameric structure of the nicotinic channel of the Torpedo electric organ (Devillers-Thiery et al, 1993), is shown in Fig. 21.12. 

Enzyme Commercial acetylcholinesterase preparation - electrical organ acetone powder (extract) from electric eel (Electrophorus electricus) (Sigma, E2384) was used. 

The preparation of AChE-biotest includes the following stages, (i). the preparation of homogenate from tissue with high cholinesterase activity (electrical organ acetone powder). Homogenate are preparated in phosphate... 

Van der Kloot, W. Loading and recycling of synaptic vesicles in the Torpedo electric organ and the vertebrate neuromuscular junction. Prog. Neurobiol. 71, 269-303, 2003. 

Significant dose-dependent effect on electric organ activity within 60 min 37... 

GEODE [General Electric organic destruction] A development of the Ultrox process in which a combination of ozone and ultraviolet radiation is used to oxidize traces of organic compounds in water. Developed by the General Electric Company and demonstrated at the Commonwealth Edison nuclear power plant at Dresden, IL, in 1989. The requirement was to reduce the concentration of total organic carbon in the process and makeup waters to the low parts-per-billion range. 

Fundamentally, the eel is simply a living battery. The tips of its head and tail represent the poles of the eel s battery . As much as 80 per cent of its body is an electric organ, made up of many thousands of small platelets, which are alternately super-abundant in potassium or sodium ions, in a similar manner to the potentials formed across axon membranes in nerve cells (see p. 339). In effect, the voltage comprises thousands of concentration cells, each cell contributing a potential of about 160 mV. It is probable that the overall eel potential is augmented with junction potentials between the mini-cells. 

Sadoulet-Puccio, H. M., Khurana, T. S., Cohen, J. B., and Kundel, L. M. (1996). Cloning and characterization of the human homologue of a dystrophin related phosphopro-tein found at the Torpedo electric organ post-synaptic membrane. Hum. Mol. Genet. 4, 44489-44496. 

A simple protocol detailed in this chapter was established to develop RNA aptamers that bind to the electric organ nAChR and that are displaced by cocaine (8) (see Fig. 1 for a scheme). This protocol can be easily transferred to SELEX applications with other receptors or cell-surface epitopes, given that these are enriched in membrane preparations. 

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