Semantic blocks

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editing. They learn as they go along, which takes much more time than if they already knew something about editing procedures. A handbook for novice scientific editors should therefore be useful and one is now being prepared [3] as a logical follow-up to the ELSE-Ciba Foundation Guide for Authors [4]. Suggestions from any former, present or potential editors of multiauthor books or conference proceedings as to what they would like to see discussed in this handbook for editors would be warmly welcomed. MAEVEO'CONNOR

Senior Editor, Ciba Foundation, U.K.

London,

References 1 Brent, L. and Holborow, J. (eds) (1974) Progress in Immunology ZZ, Vols l-5, North-Holland, Amsterdam; American Elsevier, New York 2 Saccone, C. and Kroon, A.M. (eds) (1976) The Genetic Function of Mirochondrial DNA, Elsevier/ North-Holland Biomedical Press, Amsterdam 3 O’Connor, M. and Woodford, F. P. Editing Scientific Books and Journals: An ELSE-Ciba Founaixlion Handbook, in preparation 4 O’Connor, M. and Woodford, F. P. (1975) Wriring Scientifir Papers in English: An ELSE-Ciba Foundation Guide for Authors, Elsevier/Excerpta Medics/North-Holland, Amsterdam

Round table meetings SIR: As

a long suffering participant of many scientific meetings I read with interest the articles by Gutfreund and Campbell on the usefulness of international congresses (see TIBS September, p. N 198). It is good that we question the expenditure of many millions of pounds each year, most of which goes into the well-lined, capacious pockets of hoteliers and airline operators. Even if we think that they are not useful many of us are sucked into the whirlpool of international meetings. Only when one has reached a high level of achievement in scientific endeavour and conferencemanship can one opt out without being considered a drop out. The most disturbing feature of this recurring debate.is the lack of hard data. As scientists faced with the problem of communication (for this is the purpose of any meeting) we should try to state the requirements, examine the possibilities, do some experiments and analyse the results. This is not easy but neither is research in chemical kinetics, brain function or whatever. Some years ago I was able to do an experiment [l] and came to the following conclusions that have been supported by subsequent experience : (1) the theme of meetings should be problem oriented, preferably posing an almost soluble question (2) effective communication between

participants is only possible if they can all sit round one albeit large table-this restricts the attendance to about 60 people who should already know each other fairly well (3) participants arrive at the meeting having read and thought about precirculated papers (this is probably the most difftcult feature to achieve) (4) no papers are presented and discussion starts after an outline lecture. This too is difficult for there seems to be a primitive drive (? courtship behaviour) to stand beside a screen and show off data in great detail. One way of preventing this is for any discussant to present his slides from his seat at the table, only the main and relevant features are then described, try it (5) there is an effective chairman who knows what the meeting is trying to achieve (6) the participants and their camp followers if any (husbands and wives) are accommodated in one group of buildings well away from the sins of a major city. A residential college is ideal for this, hotels are not satisfactory since it is essential for participants to have exclusive use of the

The mechanism of oxidative phosphorylation Semantic blocks SIR:As Williams says (see TIBS October, p. N 222), the areas of contention between his own views and chemiosmosis are not great. However, there are two points in his article I would like to take up. (1) Both hypotheses envisage proton power as driving ATP synthesis. It seems to me that Williams needs to specify the nature of the conductor of the proton current, or the range over which he expects it to operate. In his original hypothesis, protons were produced (by the electron transport chain) and utilised (by the ATPase) in very local environments. More recently he has suggested that ice-like pro-

bar, lounges and dining facilities so that discussion can continue to all hours (7) rooms are available for poster sessions and small discussion groups and (8) publication of the proceedings are usually a waste of valuable time for all concerned. In the experimental meeting referred to here, scientific experiments were done ‘online’ to highlight particular aspects of the problems and were transmitted to the participants by two-way closed circuit television. This proved very stimulating but imposed a very heavy load on the host institution. This sort of experiment should be tried again. With these ingredients the necessary reactions should occur and the meeting should be fun, which is hardly possible with the ‘10 minute paper, 5 minute discussion’ format of more conventional meetings. Problems still exist of course, particularly with young people wishing to enter the field. Perhaps the edited discussion of the main group might be available on video tape. However, the important thing is to analyse the problem and try new ways of communication. If these fail then at least we can go back with no feelings of guilt to a symposium ‘a drinking-party ; a convivial meeting for drinking, conversation and intellectual entertainment’ [2]. RAY COOPER

Burden Neurological Bristol, U.K. References

Institute, Stapleton,

1 Cooper, R. (1973) Nature 246, 111 2 Manten, A. A. (1976) Symposia and Symposium Publications, Elsevier, Amsterdam

tonic channels might allow communication between separate sites. Where in the membrane are these channels? The sites of proton production and utilization are certainly in rapid communication with the aqueous phases since (a) rates of change of proton concentration in the phases are quite compatible with rates of electron flow, (b) rates of phosphorylation induced by applied protonic gradients are as rapid as those coupled to electron flow, and (c) various energy-linked reactions such as reversed electron flow, transhydrogenase, ion pumping etc., which are not inhibited by oligomycin and which presumably reflect the gradients between the bulk aqueous phases, occur at rates comparable to or in excess of phosphorylation rates. What are the conduction pathways for these protons? What determines.the relative flux through the different pathways? Possibly the structured water (‘ice’) at the membrane-water interfaces might provide

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favoured conduction paths for protons (an idea suggested to me several years ago by Robin Jeacocke). But this is hardly ‘in the membrane’. (2) I am confused by .Williams’s treatment of the potential component of the protonic driving force. This latter is written by Williams as: P= V+GpH which I presume to be equivalent to A/l -H+ F

= Ap=Ar,-ZApH

where Z= 2.303 F

as given by Mitchell, so that P- Ap, Vr AY and 6pH = - ZApH. However, the text of the article suggests that Williams may envisage the components of the gradient developing in a way quite different from that suggested by Mitchell. Thus ‘. . . Note however that if I/ can only be built via 6pH.. .‘, and ‘. .the assumed parallel is with the equation of theoretical diffusion (junction) potentials. . .‘, imply that V is a proton diffusion potential, and that it can be built up only as a result of diffusion of protons across the membrane down a concentration gradient through unsuspecified channels. If this were the case; the protonic driving force P would be less than either the electrical or chemical component of the gradient (and equal to the difference between them, since these would have opposite signs), rather than greater than either component (and equal to their sum, since both would have the same sign), as suggested by Mitchell. This is of course, totally at variance with Mitchell’s postulated mechanism, in which the proton pumping activity of the electron transport system is electrogenic, and the energy from electron transport is used to perform both electrical work (in, effectively, moving the charge of the proton across the membrane) and chemical work (in changing the concentrations on either side of the membrane). In this case A’+’(or

V) may attain a high value with little or no buildup of - ZApH, since, as Mitchell has pointed out, the relative rates at which AY (or v) and - ZApH increase as a function of the rate of electrogenic proton transfer across the membrane will depend on the relative values of capacity factors for charge (electrical capacitance of the membrane) and moles of proton (buffering capacity) in the system. Certainly Williams misstates Mitchell’s position when he represents this as ‘. . V+6pH drives ATP formation, V formed from 6pH. . .’ A. R. CROFTS

Dept of Biochemistry, University of Bristol, Bristol, U.K.

Better tests are needed : The Discussion Forum between Morowitz and Williams focuses on a specific question, the mode of coupling between charge-separating devices located in the same membrane (see TIBS October, p. N222). This is by no means a new question, and it is certainly one that has exercised me over a number of years [l]. Nevertheless, it does continually become blurred as attention and controversy focus on the devices themselves, their mechanisms and their stoichiometry. The measurement of ‘membrane potentials’ (however they are defined) and pH gradients (or their absence), and the reconstitution of ‘model’ coupled systems (often with far from model lipid: protein ratios), far from resolving the question, have led to the impasse revealed in the Forum. Both authors are distinguished scholars, both are aware of the key experiments in the literature, but they come to different views; and theirs is not simply a semantic quibble. Where does the difficulty lie? Is Williams’s thermodynamic argument unsound? (He convinces me, but then I cannot claim much comSIR

Philosoph Z$EPual

1976

petence in that area.) Or has Morowitz not thought deeply enough about the work that Williams cites? (Or has he rejected some of the evidence as being invalid?) Now, schisms in science can provide a healthy stimulus to constructive work, and a consensus on an incorrect view is disastrous. But this particular argument is in danger of stagnating into an entirely counter-productive distraction. So, what should be done about it? It seems that the only way forward is either (a) to design and perform new experiments specifically to discriminate between the two viewpoints, or (b) to agree that they are experimentally indistinguishable and turn our minds to other matters. Mitchell would certainly prefer the first alternative. Although he now regards the chemiosmotic hypothesis as having reached the status of an acceptable theory (and the best available), he urges the Popperian process of critical re-evaluation [2]. Discrimination ought to come from kinetic experiments with relatively native systems, although the lateral diffusion to which Williams refers might tend to confound the kinetic distinction between delocalised and local membrane interactions. Our own early kinetic experiments [3] (as well as much other subsequent but unpublished data), have tended to indicate that coupling is a relatively local&d phenomenon, at least in mitochondira. Other laboratories, using similar approaches, have come to similar conclusions [4]. But critical re-evaluation does not now convince me that the experimental findings are open to unambiguous interpretation. Better tests are required. Has anyone any suggestions? Williams would of course be completely vindicated if oxidative phosphorylation could be demonstrated in non-vesicular systems. This is a one-way discrimination, since failure would not disprove his ideas. Nevertheless, the ‘localised lobby’, if it has faith in itself, ought to be exploring such

drawn forTlBS Paul Staplet%