Articles Alert

GEOSCIENCES

• Geophysical and petrologic constraints on bulk lunar composition indicate both differences and similarities between the Moon and the Earth's mantle. The differences probably rule out the fission origin of the Moon, and the similarities rule out capture. Impact-fission seems the most likely.

  S. Mueller, G.J. Taylor, R.J. Phillips, "Lunar composition: A geophysical and petrological synthesis," Journal of Geophysical Research, 93 (B6), 6338-52, 10 June 1988.

• Although there are apparently no plate-tectonic processes on Venus, horizontal deformation features can be seen on the planet's surface. Modeling suggests that they maybe due to gravity spreading above areas of temperature-induced ductile deformation.

  S. Smrekar, R.J. Phillips, "Gravity-driven deformation of the crust of Venus," Geophysical Research Letters, 15 (7), 693-6, July 1988.

• A series of high-pressure, high-temperature experiments on the distribution of major and minor elements strongly suggests that the Earth's mantle did not experience extensive melting during formation. Major-element bulk composition (near-chondritic) is uniform throughout the mantle.

  T. Kato, A.E. Ringwood, T. Irifune, "Experimental determination of element partitioning between silicate perovskites, garnets and liquids: Constraints on early differentiation of the mantle," Earth and Planetary Science Letters, 89(1), 123-45, June 1988.

• Examination of the uplift/subsidence history of the peripheral zones of the Laurentide and Fennoscandian ice sheets shows beyond reasonable doubt that isostatic adjustment to the removal of crustal loading takes place by flow in the astenosphere and not throughout the whole mantle.

  CB. Officer, W.S. Newman, J.M. Sullivan, D.R Lynch, "Glacial isostatic adjustment and mantle viscosity," Journal of Geophysical Research, 93 (B6), 6397-409, 10 June 1988.

• The accumulation of natural radon in houses is a known cancer risk, but epidemiological studies are hampered by the lack of long-term domestic radon measurements. However, past radon concentrations can now be "recovered," because the radon daughter lead-120 adheres to glass surfaces inside houses.

  C. Samuelsson, "Retrospective determination of radon in houses," Nature, 334 (6180), 338-40,28 July 1988.

• At least 98% of the water and noble gases in the subducting oceanic lithosphere is returned to the atmosphere through subduction-related volcanism. Subduction is therefore a highly efficient bather, preventing the return of volatiles to the mantle.

  T. Staudacher, C.J. Allègre, "Recycling of oceanic crust and sediments: the noble gas subduction barrier," Earth and Planetary Science Letters, 89 (2), 173-83, July 1988.

• A new specimen of Archaeopteryx, the sixth and largest, has been discovered in the Upper Jurassic Solnhofen limestone of Bavaria. As there can be no question of forgery in this case, the wing-feather impressions prove that Archaeopteryx did indeed have feathers.

  P. Wellnhofer, "A new specimen of Archaeopteryx," Science, 240 (4860),1790-2, 24 June 1988.

LIFE SCIENCES

• Collaboration between scientists in Boston and Sydney has spawned oligonucleotide probes capable of resolving C-type proviruses in mice into three distinct families, whose members can then be distinguished by restriction mapping. The work amounts to a major breakthrough in accessing the genome of the mouse.

  J.P. Stoye, S. Fenner, G.E. Greenoak, C. Moran, J.M. Coffin, "Role of endrogenous retroviruses as mutagens: the hairless mutation of mice," Cell, 54 (3), 383-91,29 July 1988.

• Stanley Miller, a key figure in supplying experimental evidence to support the Oparin-Haldane theory that terrestrial life emerged in a primeval soup, has exposed the misunderstandings of organic chemistry that have encouraged recent speculations about hydrothermal vents as the sites for abiogenesis.

  S.L. Miller, J.L. Bada, "Submarine hot springs and the origin of life," Nature, 334 (6183), 609-11, 18 August 1988.

• Another complication for authorities wishing to stamp out drug taking in sport has arisen. Following the discovery that apparently positive testosterone doping tests in a Swedish athlete always followed alcohol consumption, a well-controlled study confirms that drinking should be considered as at least part of the explanation for positive results.

  0. Falk, E. Palonek, I. Bjorkhem, "Effect of ethanol on the ratio between testosterone and epitestosterone in urine," Clinical Chemistry, 34 (7), 14624, July 1988.

• There is growing anxiety in North America and Europe about possible genetic damage to trees and crops by sulfur dioxide, ozone, and other atmospheric pollutants. A recent review spotlights the unknowns-and thus the urgent needs and opportunities for research.

  LF. Pitelka, "Evolutionary responses of plants to anthropogenic pollutants," Trends in Ecology and Evolution, 3(9), 233-6, September 1988.

• Studies on a closely related organism suggest that the plague bacillus can become highly virulent as a result of a single mutation. This may explain the sudden appearance of epidemics, such as the Black Death, and their subsequent decline.

  R. Rosqvist, M. Skurnik, H. Wolf-Watz, "Increased virulence of Yersinia pseudotuberculosis by two independent mutations," Nature, 334 (6182), 522-5, 11 August 1988.

• Buttressed by some 400 references to papers published over the past 12 years, reviewers from the UK Medical Research Council's Radiobiology and Cell Mutation Unit in London have produced a formidable but unusually well-written dossier on damage caused by ionizing radiation to cellular DNA.

  A.M. George, WA. Cramp, "The effects of ionizing radiation on structure and function of DNA," Progress in Biophysics and Molecular Biology, 50 (3), 121-69, 1988.

CHEMISTRY

• The preparation of molecules and ions that exist as stable ground state triplets, has important consequence in materials chemistry. One such family has recently been described.

  J. Thomaides, P. Maslak, R. Breslow, "Electron-rich hexasubstituted benzene derivatives and their oxidized cation radicals, dications with potential triplet ground states, and polycations," Journal of the American Chemical Society, 110 (12), 3970-9, 8 June 1988.

• The interaction of oxygen with low-valent porphyrins is important in biological transport and activation of oxygen. A family of compounds with rigid superstructures has been designed to define a molecular cavity on one face of the macrocycle.

  J.R Coilman, J.I. Brauman, J.R Fitzgerald, RD. Hampton, Y. Naruta, J.W. Sparapany, J.A. Ibers, "Synthesis, characterization, and X-ray structure of the Ruthenium 'picnic-basket' porphyrin," Journal of the American Chemical Society, 110 (11), 3477-85, 25 May 1988.

• The construction of molecules with extended conjugated systems that organize into non-centrosymmetric arrangements constitutes a rapidly emerging area, uniting organic molecular synthesis with macroscopic properties.

  M. Blanchard-Desce, L Ledoux, J.-M. Lehn, J. Malthête, J. Zyss, "Push-pull polyenes and carotenoids: Synthesis and nonlinear optical properties," Journal of the Chemical Society, Chemical Communications, (11), 737-40, June 1988.

• The assignment of molecular structure from nuclear magnetic resonance spectral data has allowed important advances in nearly hall branches of chemistry. The use of two-dimensional techniques for detailed spectral interpretation is discussed in a recent study.

  H. Kessler, M. Gehrke, C. Griesinger, "Two-dimensional NMR spectroscopy Background and overview of the experiments," Angewandte Chemie, International Edition, 27 (4), 490-537, April 1988.

• Spatial control of organometallic reagents within well-defined clay layers held at defined distances is exemplified by a classic catalytic reaction, described in a recent article.

  E.P. Giannelis, E.G. Rightor, T.J. Pinnavaia, "Reactions of metal-cluster carbonyls in pillared clay galleries: Surface coordination chemistry and Fischer-Tropsch catalysis," Journal of the American Chemical Society, 110 (12), 3880-5, 8 June 1988.

• Distinguishing between concerted and stepwise reactions is usually accomplished using stereochemical or kinetic criteria. An ambiguity is examined in a recent treatment of palladium-catalyzed cycloadditions.

  B.M. Trost, M.L. Miller, "Criteria for concertedness in cycloadditions," Journal of the American Chemical Society, 110 (11), 3687-9, 25 May 1988.

PLANT AND ANIMAL SCIENCES

• Nucella snails vary in shell color within and between populations. In shores exposed to high waves, the populations are very polymorphic, although brown-pigmented snails predominate; in more sheltered locations, the snails are predominately white and the populations are less polymorphic. The reason? White snails are better able to sustain the high temperatures and extreme desiccation that occur in protected shores, whereas the brown snails grow faster and therefore prevail where desiccation and high temperature do not place them at a disadvantage.

  R.J. Etter, "Physiological stress and color polymorphism in the intertidal snail Nucella lapillus," Evolution, 42(4), 660-80, July 1988.

• The mating calls of frogs differ not only between species, but also between local populations of the same species. In cricket frogs, two neighboring populations differ in the frequency of the call and the frequency to which the ear is most sensitive. Genetic differences between local populations can, therefore, persist and be enhanced.

  M.J. Ryan, W. Wilczynski, "Coevolution of sender and receiver: Effect on local mate preference in cricket frogs," Science, 240 (4860), 1786.8, 24 June 1988.

• Drosophila subobscura, a well-known Old World species, appeared in Chile in 1978 and in western North America in 1982. It has spread in both Americas and now extends over a north-to-south zone longer than 2,000 km in each; in many places it has become the most common Drosophila species. Genetic variants, identified by chromosome-sequence rearrangements, have rapidly evolved in the two Americas in patterns similar to those in Europe.

  A. Prevosti, G. Ribo, L. Serra, M. Aguade, J. Balana, M. Monclus, F. Mestres, "Colonization of America by Drosophila subobscura: Experiment in natural populations that supports the adaptive role of the chromosomal-inversion polymorphism," Proceedings of the National Academy of Sciences of the USA, 85 (15), 5597-600, August 1988.

• Birds learn songs by listening to those sung by other birds of the same species. In cowbirds, females lead males to modify their songs by expressing with wing strokes which ones they like.

  M.J. West, A.R King, "Female visual displays affect the development of male song in the cowbird," Nature, 334 (6179), 244-6, 21 July 1988.

• Some fishes, mollusks, and plants change sex over the course of their lives. Sex change occurs in species where the success of reproduction as a function of age and size differs between the sexes. Whether protandry (the change from male to female) or protogyny (from female to male) occurs and when it will happen depend on which sequence maximizes reproductive success.

  R.R. Warner, "Sex change and the size-advantage model," Trends in Ecology and Evolution, 3 (6), 133-6, June 1988. [Also: W.G. Wright, "Sex change in the mollusca," Ibid., 137-40.]

• Generalists are predators that feed on several species. Specialists, such as the bumblebee Bombus consobrinus, limit themselves to one prey, but gain by becoming more effective at exploiting it.

  T.M. Laverty, R.C. Plowright, "Flower handling by bumblebees: a comparison of specialists and generalists," Animal Behavior, 36 (3), 733-40, June 1988.