- Email: [email protected]
A plea for peroxisomes
TIBS -January 1980
X
S p a i n " policy changes required SIR: Almost everyone familiar with the situation of the scientific research in Spain would agree with the Municio and Vfizquez report (TIBS, Sept., 1979, N 202) which discusses t h e problems faced by the biochemical research establishment i n Spain. However, the article overemphasizes the financial exigency of the situation. Other not so apparent and more subtle problems exist as well. Some of them were stated, at least, indirectly; these include differences in teaching level, extent and efficacy of teaching, lack of appropriate numbers of supporting staff and facilities and bureaucratic control. However, an important background factor was, in my opinion, overlooked. The implicit assumption that the sole purpose of the massive expansion of the universities was to promote the development of science and research is open to question. In my opinion, the increase in the number of universities had the double purpose of manufacturing a great number of persons with university degrees to fill the various occupations in an expanding society (teachers, administrators etc.) and, at the same time, to promote the image of a modern and technological Spain on an international level. The quality of the technical and scientific education given in these universities left much to be desired due to the lack of funds, well-qualified personnel, and library and laboratory facilities. The education was characterized by dogmatism and memorization, not the most appropriate qualities to promote genuine scientific enquiry. Similarly, the concept that the unique purpose in the creation and expansion of the Scientific Research Council (Consejo Superior de Investigaciones Cientfficas) was to promote research and development can be argued. The geographical distribution of research institutes seems to be based on political priorities: there is not a single research institute in the Basque provinces (provinces with high industrial output) while a disproportionate number of them are localized in Madrid. Research centers in rural areas are almost nonexistent or ineffective. This distribution would prevent a rational development of research in places near agricultural and industrial centers (Nature (1979), 281, 424). Yet there is a scientific and academic community in Spain. University classrooms and laboratory environments exist. Significant contributions and respect in the scientific community have been achieved through extensive work and training in
foreign laboratories as well as by the dogged dedication of gifted young men and women. The future holds little promise given the strength of the political demise. The positions available to university graduates will decrease to zero once the initial demand for teachers, administrators and the like ceases. The nearsighted research and development effort failed9 to create an active, independent and society-related research program, so that the demand for investigators remains very low. The solu-
tion to the present crisis demands 'deep changes in our scientific and technological policy' (Nature (1979), 281, 417). The financial crisis that presently affects the world may be the final blow, making any changes in the scientific policy difficult or impossible to implement. CELERINOABAD ZAPATERO Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, U.S.A.
Shuttle systems A plea for peroxisomes SIR: We found the recent article by A. G. Dawson on shuttle systems (TIBS, Aug., 1979, 171) to be both interesting and stimulating. At the same time, though, we cannot agree that mitochondria are the only oxidative organelles worthy of mention in regard to the provision of substrates for the o~idation of cytosolic NADH. It is now well established, for example, that a considerable proportion of the oxygen consumption in tissues such as liver and kidney may be of peroxisomal origin and a wide range of substrates (including hydr0xy acids, fatty acids, amino acids and ethanol) may be oxidized in these organeiles. Regard should be given to the possibility of the products of these reactions diffusing to the cytosol, too, and being capable of influencing the redox status there*. * The metaboliccapabilities of the peroxis0mewere the subject of comment at greater length in a recent article in TIBS, Oct., 1979,233.
c. J. MASTERS R. S. HOLMES Griffith University, Nathan QLD 4111, Australia.
TIBS welcomes Letters to the Editor on any topic of interest to our readers. Please be as concise as possible. Letters should be sent to: Staff Editor, Trends in Biochemical Sciences, Elsevier/North-Holland Biomedical Press, 14A Regent St., Cambridge CB2 1DB, U.K.
Index to Advertisers Beckman XX Elsevier/North-Holland Biomedical Press V, XI, XIII, XVI Pergamon Press XIX Radiochemical Centre V
SIR: The point raised by Drs Masters and Holmes is, of course, quite valid. Peroxisomes contribute significantly to the consumption of oxygen by certain tissues and, to the extent that peroxisomal enzymes act as alternatives to cytosolic enzymes in the oxidation of substrates such as lactate or ethanol, these organelles must exert some influence on the redox status of the cytosol. Also, there is the intriguing possibility, first canvassed in 1965 b y Baudhuin, Muller, Poole and de Duve (Biochem. Biophys. Res. Comm. 20, 53) and since elaborated by de Duve and colleagues, that the redox couples lactate/pyruvate and ethanol/ acetaldehyde might participate in cyclic operations to bring about the transfer of reducing equivalents from cytosolic NADH to peroxisomal oxygen. However, because peroxisomal lactate oxidase has a very low affinity for lactate (Kin approx. 9 raM), a lactate/pyruvate cycle seems unlikely to have much physiological significance. Also, although de Duve has calculated that, in the normal liver, the rate of ethanol peroxidation might be close to 0.1 ~mol/ min per g wet wt, this represents only 5-10% of the total capacity of liver cells for transferring cytosolic reducing equivalents to oxygen (see, for instance, Berry et at., Biochem. J. (1974), 140, 355). Moreover, to the best of my knowledge, the existence of shuttle systems involving peroxisomes has not been demonstrated experimentally. It was for these various reasons that I chose, perhaps unjustly, to confine my discussion to the rather better understood shuttles that transfer reducing equivalents to the mitochondria. A. G. DAWSON Dept. of Biochemistry, University of Sydney, NSW 2006, Australia.
X
S p a i n " policy changes required SIR: Almost everyone familiar with the situation of the scientific research in Spain would agree with the Municio and Vfizquez report (TIBS, Sept., 1979, N 202) which discusses t h e problems faced by the biochemical research establishment i n Spain. However, the article overemphasizes the financial exigency of the situation. Other not so apparent and more subtle problems exist as well. Some of them were stated, at least, indirectly; these include differences in teaching level, extent and efficacy of teaching, lack of appropriate numbers of supporting staff and facilities and bureaucratic control. However, an important background factor was, in my opinion, overlooked. The implicit assumption that the sole purpose of the massive expansion of the universities was to promote the development of science and research is open to question. In my opinion, the increase in the number of universities had the double purpose of manufacturing a great number of persons with university degrees to fill the various occupations in an expanding society (teachers, administrators etc.) and, at the same time, to promote the image of a modern and technological Spain on an international level. The quality of the technical and scientific education given in these universities left much to be desired due to the lack of funds, well-qualified personnel, and library and laboratory facilities. The education was characterized by dogmatism and memorization, not the most appropriate qualities to promote genuine scientific enquiry. Similarly, the concept that the unique purpose in the creation and expansion of the Scientific Research Council (Consejo Superior de Investigaciones Cientfficas) was to promote research and development can be argued. The geographical distribution of research institutes seems to be based on political priorities: there is not a single research institute in the Basque provinces (provinces with high industrial output) while a disproportionate number of them are localized in Madrid. Research centers in rural areas are almost nonexistent or ineffective. This distribution would prevent a rational development of research in places near agricultural and industrial centers (Nature (1979), 281, 424). Yet there is a scientific and academic community in Spain. University classrooms and laboratory environments exist. Significant contributions and respect in the scientific community have been achieved through extensive work and training in
foreign laboratories as well as by the dogged dedication of gifted young men and women. The future holds little promise given the strength of the political demise. The positions available to university graduates will decrease to zero once the initial demand for teachers, administrators and the like ceases. The nearsighted research and development effort failed9 to create an active, independent and society-related research program, so that the demand for investigators remains very low. The solu-
tion to the present crisis demands 'deep changes in our scientific and technological policy' (Nature (1979), 281, 417). The financial crisis that presently affects the world may be the final blow, making any changes in the scientific policy difficult or impossible to implement. CELERINOABAD ZAPATERO Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, U.S.A.
Shuttle systems A plea for peroxisomes SIR: We found the recent article by A. G. Dawson on shuttle systems (TIBS, Aug., 1979, 171) to be both interesting and stimulating. At the same time, though, we cannot agree that mitochondria are the only oxidative organelles worthy of mention in regard to the provision of substrates for the o~idation of cytosolic NADH. It is now well established, for example, that a considerable proportion of the oxygen consumption in tissues such as liver and kidney may be of peroxisomal origin and a wide range of substrates (including hydr0xy acids, fatty acids, amino acids and ethanol) may be oxidized in these organeiles. Regard should be given to the possibility of the products of these reactions diffusing to the cytosol, too, and being capable of influencing the redox status there*. * The metaboliccapabilities of the peroxis0mewere the subject of comment at greater length in a recent article in TIBS, Oct., 1979,233.
c. J. MASTERS R. S. HOLMES Griffith University, Nathan QLD 4111, Australia.
TIBS welcomes Letters to the Editor on any topic of interest to our readers. Please be as concise as possible. Letters should be sent to: Staff Editor, Trends in Biochemical Sciences, Elsevier/North-Holland Biomedical Press, 14A Regent St., Cambridge CB2 1DB, U.K.
Index to Advertisers Beckman XX Elsevier/North-Holland Biomedical Press V, XI, XIII, XVI Pergamon Press XIX Radiochemical Centre V
SIR: The point raised by Drs Masters and Holmes is, of course, quite valid. Peroxisomes contribute significantly to the consumption of oxygen by certain tissues and, to the extent that peroxisomal enzymes act as alternatives to cytosolic enzymes in the oxidation of substrates such as lactate or ethanol, these organelles must exert some influence on the redox status of the cytosol. Also, there is the intriguing possibility, first canvassed in 1965 b y Baudhuin, Muller, Poole and de Duve (Biochem. Biophys. Res. Comm. 20, 53) and since elaborated by de Duve and colleagues, that the redox couples lactate/pyruvate and ethanol/ acetaldehyde might participate in cyclic operations to bring about the transfer of reducing equivalents from cytosolic NADH to peroxisomal oxygen. However, because peroxisomal lactate oxidase has a very low affinity for lactate (Kin approx. 9 raM), a lactate/pyruvate cycle seems unlikely to have much physiological significance. Also, although de Duve has calculated that, in the normal liver, the rate of ethanol peroxidation might be close to 0.1 ~mol/ min per g wet wt, this represents only 5-10% of the total capacity of liver cells for transferring cytosolic reducing equivalents to oxygen (see, for instance, Berry et at., Biochem. J. (1974), 140, 355). Moreover, to the best of my knowledge, the existence of shuttle systems involving peroxisomes has not been demonstrated experimentally. It was for these various reasons that I chose, perhaps unjustly, to confine my discussion to the rather better understood shuttles that transfer reducing equivalents to the mitochondria. A. G. DAWSON Dept. of Biochemistry, University of Sydney, NSW 2006, Australia.