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In his early work, Frohlich carried out a theoretical study of the electrical oscillations of sections of biological membranes and showed that a supply of metabolic energy above a critical rate could lead to coherent electrical oscillations. Such excitations are not, however, restricted to membranes and it is possible for interactions to occur between systems of equal frequency at a distance at which ordinary chemical interaction is absent and electrostatic interaction is screened. The possibility of coordinated activity of large regions thus appears. Estimates of the frequency of coherent oscillations of membranes gave values in the 1011 Hz range − the same as that of electromagnetic millimeter waves. If biological systems do in fact make internal use of such excitations then great sensitivity to external radiation at the relevant frequencies should be expected. Work reported at the conference suggests such sensitivity exists.
A remarkable 44 per cent increase in the fertility of Drosophila melanogaster was reported (G. Nimtz, University of Koln) to occur in the first generation after irradiation of pupae for 5 days with microwaves (40 GHz) at an intensity of only 10 μW cm−2. In a study of puffing patterns in the giant chromosomes of Acricotopus lucidus (F.Kremer, Max-Planck-Institut, Stuttgart), a fivefold increase in the number of condensations of Balbiani rings (α< 0.5 per cent) was observed after only 2 h of low-intensity irradiation at 64-69 GHz. Reproducible changes of about 10 per cent in the average growth rate of yeast cells Saccharomyces cerevisiae (W.Grundler, Gesellschaft fur Strahlen- und Umweltforschung, Neuherberg), were observed at several frequencies near 42 GHz. Use of fine-scaled frequency tuning showed the response to be highly resonant, such that detuning by only 1 part in 104 obliterated the effect. The sharpness of frequency response together with a step-like dependence on the microwave intensity is in agreement with theoretical requirements.
When human red blood cells are dispersed in plasma they appear to carry out brownian movement until they attach to each other, forming rouleaux which, under the microscope, have the appearance of stacks of coins. In extensive microscopic investigations, S.Rowlands (University of Calgary) found that the erythrocytes appear to rush forwards towards each other once they have approached to within about 4 μm. Analysis of the movement in terms of the Smoluchowsky theory permits a quantitative evaluation of the interaction. If the attraction arose from coherent membrane oscillation then the measured attraction satisfies the requirements of the theory; it disappears when the membrane potential is removed by a change of the plasma pH, or when they are depleted of their metabolic energy. The attraction reappears when both are restored.
What kind of biological structures might be responsible for these remarkable findings? Current ideas on the ultra-structure of various cells (J. Clegg, University of Miami) lay emphasis on the microtrabecular lattice and its attendant 'bound' water as a possible vehicle for cytoplasmic organization in general and for the transfer of coherent excitation in particular. Mouse fibroblasts (L cells) suspended in 0.3 M sorbitol contained only 0.5 g H2O per g dry mass, and were virtually in the solid state, yet metabolized in a fashion indistinguishable from that of 'normal' fibroblasts. Evidently a cytoplasm exhibiting a bulk aqueous milieu is not a feature crucial to cellular function.
It is now widely recognized that the membranous systems of electron transport phosphorylation effect free-energy transfer by a bioelectrical mechanism, in that spatially separate protein complexes have been shown to act as more-or-less reversible proton pumps. Various studies, however, led to the conclusion (D. Kell, University College of Wales) that the free-energy transfer was effected between specific individual complexes, so that traditional stochastic ensemble models must be proscribed. A coherent excitation is thus л particularly attractive possibility for explaining the properties of this process.
F.Keilmann is in the Max-Planck Institut fur Festkoerperphysik, PostFach 80 06 65, 7000 Stuttgart 80 and
D.G. Kell in the Department of Botany and Microbiology, University College of Wales, Aberystwyth SY23 3DA.
* The international symposium on “Coherent Excitations in Biological Systems”, held at Bad Neuenahr on 29 November − 1 December 1982, was sponsored by IBM Germany; chairman H. Frohlich. The proceedings are to be published by Springer Verlag.
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