Catálogo de publicaciones - revistas

<jats:p> <jats:bold>The Economic Laws of Scientific Research.</jats:bold> TERENCE KEALEY. St. Martin's, New York, 1997. xii, 382 pp. $75, ISBN 0-312-12847-9; paper, $19.95, ISBN 0-312-17306-7. Published in the UK by Macmillan. £47.50, ISBN 0-333-56045-0; paper, £16.99, ISBN 0-333-65755-1. </jats:p>

<jats:p> <jats:bold>Adaptation.</jats:bold> MICHAEL R. ROSE and GEORGE V. LAUDER, Eds. Academic Press, San Diego, 1996. xiv, 511 pp., illus. $69.95 or £52, ISBN 0-12-596420-x; paper, $34.95 or £24.95, ISBN 0-12-596421-8. </jats:p>

<jats:p>Tremendous debate was stirred by the announcement of the successful cloning of a sheep from a differentiated somatic cell. One result was that the National Bioethics Advisory Commission was asked by the president of the United States to report on the ethical and legal issues arising from the possibility that the cloning of humans could become a reality. In this Policy Forum, the chairman of that commission, Harold Shapiro of Princeton University, summarizes the recommendations of the panel and the challenges and concerns that led them to advocate a moratorium on the cloning of humans at the present time.</jats:p>

<jats:p>Numerical simulations of particles placed in orbital resonances in the main asteroid belt show that the typical dynamical lifetimes of objects that could become near-Earth asteroids or meteorites are only a few million years, with the majority destroyed by being transferred to Jupiter-crossing orbits or being driven into the sun. Particles that fortuitously migrate to the terrestrial planet region may be pushed to high-inclination orbits by resonances but are still dynamically eliminated on time scales of ∼10 million years. These shorter lifetimes may require a reassessment of our qualitative understanding about near-Earth asteroids and meteorite delivery.</jats:p>

<jats:p> Small structural perturbations in the enzyme isocitrate dehydrogenase (IDH) were made in order to evaluate the contribution of precise substrate alignment to the catalytic power of an enzyme. The reaction trajectory of IDH was modified (i) after the adenine moiety of nicotinamide adenine dinucleotide phosphate was changed to hypoxanthine (the 6-amino was changed to 6-hydroxyl), and (ii) by replacing Mg <jats:sup>2+</jats:sup> , which has six coordinating ligands, with Ca <jats:sup>2+</jats:sup> , which has eight coordinating ligands. Both changes make large (10 <jats:sup>−3</jats:sup> to 10 <jats:sup>−5</jats:sup> ) changes in the reaction velocity but only small changes in the orientation of the substrates (both distance and angle) as revealed by cryocrystallographic trapping of active IDH complexes. The results provide evidence that orbital overlap produced by optimal orientation of reacting orbitals plays a major quantitative role in the catalytic power of enzymes. </jats:p>