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Isn't it time to enforce the freedom to meet?
358
T I B S - O c t o b e r 1983
Letters to the Editor Isn't it t i m e t o enforce the freedom to meet? SIR: It was during the 12th International Congress of Biochemistry, in Perth, Australia, August 1982, that many of us signed a petition, addressed to the Australian Government, strongly protesting its refusal to issue entry visas to two distinguished Russian scientists who had been invited to attend and speak at the Congress. Reporting on this incident ( T I B S (1982) 7, 351) Drs H. G. Wood and W. J. Whelan, President and General Secretary respectively of the International Union of Biochemistry, wrote, 'It was a meeting in which a serious blow to the freedom to meet was struck.' And they added: 'It is very much hoped that this has been an isolated occurrence . . . . Unhappily, that most reprehensible, in fact wholly unacceptable, attitude is still quite prevalent. This year, I was asked by the Organizing Committee of the l lth International Seaweed Symposium, held in
Qingdao, China, between 19-25 June, 1983, to deliver a symposium talk. I agreed, and was so listed in the final program (3rd Circular, p. 6). The fast circular announcing the meeting indicated that 'all' those who are i n t e r e s t e d . . , are invited to attend'. Since China has no relations with Israel, I was instructed to apply for a visa in a country that does, so when 1 was next in the US I visited the Chinese Embassy in Washington, D.C. That embassy refused to issue me the requested visa until specific instructions to that effect were received from China. A long series of telex exchanges with Dr Tseng, the Chairman of the Chinese Committee for the meeting, resulted in a telex informing me that unless I could obtain a passport or some other 'valid international travel permit from a country having diplomatic relations with China,', the veto would be 'beyond our control'.
Intermembrane space in mitochondria and the mechanism(s) of oxidative phosphorylation SIR: The report by R. J. P. Williams ~brings up the question of the structure of mitochondria in relation to the mechanism of oxidative phosphorylation. According to Mitchell's chemiosmotic theory, the exergonic redox reactions of the respiratory system are coupled to the synthesis of ATP exclusively through the transmembrane movement of protons, in the bulk aqueous phases on the opposite sides of the coupling membrane. Williams regards the bulk aqueous protons as part of a 'back-up store or buffering system for energy transduclion' and not an essential feature of the mechanism of oxidative phosphorylation. He emphasizes the non-equilibrium nature of the anhydrous or partially hydrated protons confined within the membrane phase by the diffusion barriers opposing equilibration between the bulk and intramembrane protons. These diffusion barriers are thought to be provided in the architecture of the coupling membrane. Does the structure of the mitochondria dictate any constraints on the mechanism of oxidative phosphorylation? It was demonstrated several years ago 2"a'a that the mitochondria in rapidly frozen tissues in situ and subjected to freeze-substitution or freeze-drying, do not reveal the conventional intermembrane space in the cristae or between the inner and outer membrane (Fig. 1). These mere-
branes appear in the electron micrographs as five-layered (-~ 130A thick) and resemble the tight junctions in sections. However if the tissue (brain and pancreas) is subjected to asphyxiation (8 rain to 30 min) prior to rapid freezing and subsequently processed by freeze-substitution, the conventional, seven-layered structure of mitochondria becomes discernible and a distinct intermembrane space becomes apparent in electron micrographs. The seven-layered structure results from swelling as both five-layered and seven-layered membranes are seen along the same cristae. The point to emphasize is that the extensive intermembrane space seen in mitochondria in the routinely fixed tissues that could serve as the bulk aqueous phase in oxidative phosphorylation, is an artifact. If an extremely narrow (-+ IOA) intermembrane space were to exist in mitochondria in situ, it may not be resolved by the currently available methods employed for the preparation of tissues for examination by electron microscopy. Such a narrow intermembrane space would argue against the possibility of any bulk aqueous flows as most of the water would have to be structured. This physical picture lends support to the suggestion due to Kell 5 in which he envisages the presence of a Gouy-Chapman layer which extends to about 1()~ from the
Drs Wood and Whelan refer to such incidents as 'throwbacks to such occurrences 20 or 25 years ago which we have come to think were things of the past'. Unfortunately this is not the case. In the main, the international scientific community has meticulously and successfully maintained its stand on the freedom to meet and to discuss. In that, it was perhaps unique and certainly exemplary in a world of boycotts and counter-boycotts. Has not the time come for ICSU to follow its proclaimed stand on these matters with actions that will make it unequivocally clear to those countries that discriminate against scientists that boycotts and ostracisms of this kind will not be tolerated by the international scientific community? MORDHAY AVRON
Department of Biochemistry, The Weizmann Institute of Science, Rehovot, Israel. surface of the membrane. This layer is comprised of a first row of contact adsorbed, oriented water molecules and a second overlying row of hydrated ions and protons. On account of this layer, a strong resistive and capacitative barrier is of/ered to the protonic flows between the bulk phase and the membrane surface. "lhe innermost layer of oriented water molecules provides a structure uniquely adapted for the rapid conduction of protons by a mechanism which permits two,,ders
l tg. ] life lyl)tcal ~trur t , r c ~] a mtlocllondrion ~'i.; li¢l/iz~'(/ ill ~,lltl DI t~Ipid/t'oZ~'tl
Rels 2.3 and 4 ). h t; i'mplia~tzed lltal the rapidffeezitl[~ 14.fl'+ dora" lt il/l¢ lltl tttl x. / ) r i o t < ]l('lni('tl[ JL~tlliOII OF CFVO[)IOI~'( IIOtl tl,*ld I ~, [dx~'ly I o pl<"+<'t'l't' ill ~,iltlOF~tltlIZtlllt)tl
T I B S - O c t o b e r 1983
Letters to the Editor Isn't it t i m e t o enforce the freedom to meet? SIR: It was during the 12th International Congress of Biochemistry, in Perth, Australia, August 1982, that many of us signed a petition, addressed to the Australian Government, strongly protesting its refusal to issue entry visas to two distinguished Russian scientists who had been invited to attend and speak at the Congress. Reporting on this incident ( T I B S (1982) 7, 351) Drs H. G. Wood and W. J. Whelan, President and General Secretary respectively of the International Union of Biochemistry, wrote, 'It was a meeting in which a serious blow to the freedom to meet was struck.' And they added: 'It is very much hoped that this has been an isolated occurrence . . . . Unhappily, that most reprehensible, in fact wholly unacceptable, attitude is still quite prevalent. This year, I was asked by the Organizing Committee of the l lth International Seaweed Symposium, held in
Qingdao, China, between 19-25 June, 1983, to deliver a symposium talk. I agreed, and was so listed in the final program (3rd Circular, p. 6). The fast circular announcing the meeting indicated that 'all' those who are i n t e r e s t e d . . , are invited to attend'. Since China has no relations with Israel, I was instructed to apply for a visa in a country that does, so when 1 was next in the US I visited the Chinese Embassy in Washington, D.C. That embassy refused to issue me the requested visa until specific instructions to that effect were received from China. A long series of telex exchanges with Dr Tseng, the Chairman of the Chinese Committee for the meeting, resulted in a telex informing me that unless I could obtain a passport or some other 'valid international travel permit from a country having diplomatic relations with China,', the veto would be 'beyond our control'.
Intermembrane space in mitochondria and the mechanism(s) of oxidative phosphorylation SIR: The report by R. J. P. Williams ~brings up the question of the structure of mitochondria in relation to the mechanism of oxidative phosphorylation. According to Mitchell's chemiosmotic theory, the exergonic redox reactions of the respiratory system are coupled to the synthesis of ATP exclusively through the transmembrane movement of protons, in the bulk aqueous phases on the opposite sides of the coupling membrane. Williams regards the bulk aqueous protons as part of a 'back-up store or buffering system for energy transduclion' and not an essential feature of the mechanism of oxidative phosphorylation. He emphasizes the non-equilibrium nature of the anhydrous or partially hydrated protons confined within the membrane phase by the diffusion barriers opposing equilibration between the bulk and intramembrane protons. These diffusion barriers are thought to be provided in the architecture of the coupling membrane. Does the structure of the mitochondria dictate any constraints on the mechanism of oxidative phosphorylation? It was demonstrated several years ago 2"a'a that the mitochondria in rapidly frozen tissues in situ and subjected to freeze-substitution or freeze-drying, do not reveal the conventional intermembrane space in the cristae or between the inner and outer membrane (Fig. 1). These mere-
branes appear in the electron micrographs as five-layered (-~ 130A thick) and resemble the tight junctions in sections. However if the tissue (brain and pancreas) is subjected to asphyxiation (8 rain to 30 min) prior to rapid freezing and subsequently processed by freeze-substitution, the conventional, seven-layered structure of mitochondria becomes discernible and a distinct intermembrane space becomes apparent in electron micrographs. The seven-layered structure results from swelling as both five-layered and seven-layered membranes are seen along the same cristae. The point to emphasize is that the extensive intermembrane space seen in mitochondria in the routinely fixed tissues that could serve as the bulk aqueous phase in oxidative phosphorylation, is an artifact. If an extremely narrow (-+ IOA) intermembrane space were to exist in mitochondria in situ, it may not be resolved by the currently available methods employed for the preparation of tissues for examination by electron microscopy. Such a narrow intermembrane space would argue against the possibility of any bulk aqueous flows as most of the water would have to be structured. This physical picture lends support to the suggestion due to Kell 5 in which he envisages the presence of a Gouy-Chapman layer which extends to about 1()~ from the
Drs Wood and Whelan refer to such incidents as 'throwbacks to such occurrences 20 or 25 years ago which we have come to think were things of the past'. Unfortunately this is not the case. In the main, the international scientific community has meticulously and successfully maintained its stand on the freedom to meet and to discuss. In that, it was perhaps unique and certainly exemplary in a world of boycotts and counter-boycotts. Has not the time come for ICSU to follow its proclaimed stand on these matters with actions that will make it unequivocally clear to those countries that discriminate against scientists that boycotts and ostracisms of this kind will not be tolerated by the international scientific community? MORDHAY AVRON
Department of Biochemistry, The Weizmann Institute of Science, Rehovot, Israel. surface of the membrane. This layer is comprised of a first row of contact adsorbed, oriented water molecules and a second overlying row of hydrated ions and protons. On account of this layer, a strong resistive and capacitative barrier is of/ered to the protonic flows between the bulk phase and the membrane surface. "lhe innermost layer of oriented water molecules provides a structure uniquely adapted for the rapid conduction of protons by a mechanism which permits two,,ders
l tg. ] life lyl)tcal ~trur t , r c ~] a mtlocllondrion ~'i.; li¢l/iz~'(/ ill ~,lltl DI t~Ipid/t'oZ~'tl
Rels 2.3 and 4 ). h t; i'mplia~tzed lltal the rapidffeezitl[~ 14.fl'+ dora" lt il/l¢ lltl tttl x. / ) r i o t < ]l('lni('tl[ JL~tlliOII OF CFVO[)IOI~'( IIOtl tl,*ld I ~, [dx~'ly I o pl<"+<'t'l't' ill ~,iltlOF~tltlIZtlllt)tl