Articles Alert

The Scientist has asked a group of experts to comment periodically upon recent articles that they have found noteworthy. Their selections, presented here in every issue, are neither endorsements of content nor the result of systematic searching. Rather, the list represents personal choices of articles the columnists believe the scientific community as a whole may also find interesting. Reprints of any articles cited here may be ordered through The Genuine Article, 3501 Market St., Philadelphia, Pa. 19104, or by telephoning (215) 386-4399. COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. The world was startled last November by the computer virus (or worm) that infected thousands of computers on Internet. A recent article looks at password-cracking algorithms that allow viruses to migrate. Other articles in a special section on "The Worm Story" deal with different aspects of the November infection, including a summary from the Cornell commission that investigated the incident. D. Seeley, "Password cracking: a game of wits;" Communications of the ACM, 32, 700-3, June 1989. (University of Utah, Salt Lake City) In a distributed network of computers and workstations, users may save n copies of a file to guard against losing it. This practice entails considerable storage costs over all the users on the network. Similar problems exist for transmitting a file from one node to another over a path that may fail. An informationdispersal algorithm (IDA) has been presented that reduces the amount stored or transmitted, but with equal reliability. M.O. Rabin, "Efficient dispersal of information for security, load balancing, and fault tolerance," Journal of the Association for Computing Machinery, 36, 335-48, April 1989. (Harvard University, Cambridge, Mass.) Autonomous intelligent machines have been part of the future for decades of science fiction literature. A recent article describes the locomotion, perception, and reasoning components of a six-legged robot being designed and built for exploration of Mars. Other articles in a special issue describe other projects, and collectively they provide a state-of-the-art report on this technology. J. Bares, et al., "Ambler: an autonomous rover for planetary exploration," IEEE Computer, 22, 18-26, June 1989. (Carnegie-Mellon University, Pittsburgh, Pa.) Most text retrieval systems require queries to be formulated in a formal way (for example, in Boolean logic). Also, most assume that the user has a rather precise idea of what he or she is looking for. A current paper presents a flexible, interactive browsing tool that helps overcome these problems. R.H. Thompson, W.B. Croft, "Support for browsing in an intelligent text retrieval system," International Journal of Man-Machine Studies, 30, 639-68, June 1989. (Hughes Aircraft, Fullerton, Calif.; University of Massachusetts, Amherst) High-speed computation frequently depends on a pipeline, a mechanism for staging computations for concurrent execution. In the prestigious Turing Award lecture, the author categorizes several types of pipelines and looks at a new type of event-driven pipeline. I.E. Sutherland, "Micropipelines," Communications of the ACM, 32, 720-38, June 1989. (Sutherland, Sproull and Associates, Palo Alto, Calif.) CHEMISTRY BY RON MAGOLDAMedical Products Department E.I. Du Pont de Nemours & Co. Wilmington, Del. The study of plasma lipids and lipoprotein metabolism has attracted significant interest. A recent review gives an excellent survey of fish oil, a controversial therapy for the treatment of hyperlipidermia. W.S. Harris, "Fish oils and plasma lipid and lipoprotein metabolism in humans: a critical review," Journal of Lipid Research, 30, 785-807, June 1989. (University of Kansas Medical Center, Kansas City) A mild and convenient method for the selective deprotection of an acetate in the presence of a benzoate has been described. L.H.B. Baptistella, J.E dos Santos, K.C. Ballabio, A.J. Marsaioli, "l,8-diazabicyclo[5.4.0]undec-7-ene as a mild deprotective agent for acetyl groups," Synthesis, 6, 436-8, June 1989. (Universidade Estadual de Campinas, Brazil) An excellent synthetic method for the preparation of unnatural amino acids has recently been reported. A.-S. Carlstr6m, T. Frejd, "Palladium-catalyzed synthesis of didehydroamino acid derivatives," Synthesis, 6, 414-18, June 1989. (University of Lund, Sweden) Polymerase chain reaction is a powerful method that has made a significant impact on molecular biology. A recently published review offers an outstanding description of this new technology. T.J. White, N. Arnheim, H.A. Erlich, "The polymerase chain reaction," Trends in Genetics, 5, 185-9, June 1989. (Hoffmann-La Roche, Inc., and Cetus Corp., Emeryville, Calif.; University of Southern California, Los Angeles) Techniques in molecular biology have now made possible the cloning and expression of the skeletal muscle ryanodine receptor (400-450 KD). Based on the protein sequence, a model is presented that explains the role of the ryanodine receptor in calcium transport and the structural connection between the sarcoplasmic reticulum and the transverse tubules of skeletal muscles. H. Takeshima, S. Nishimura, T. Matsumoto, H. Ishida, et al., "Primary structure and expression from complementary DNA of skeletal muscle ryanodine receptor," Nature, 339, 439-45, 8 June 1989. (Kyoto University, Japan; Miyazaki Medical College, Japan; Keio University School of Medicine, Tokyo, Japan) LIFE SCIENCES BY SIMON SILVERDepartment of Microbiology & ImmunologyUniversity of Illinois. Chicago, Ill. Some findings are too good to believe. The report in Cell of introducing genes into mice Oust by soaking sperm incloned DNA prior to in vitro fertilization) will radically alter animal breeding—if it can be confirmed and extended. M. Lavitrano, A. Camaioni, V.M. Fazio, S. Dolci, et al., "Sperm cells as vectors for introducing foreign DNA into eggs: genetic transformation of mice," Cell, 57, 717-23, 2 June 1989. (Institute of Biomedical Technology, Rome, Italy; University of Rome, Italy; Polo Biologico Integrato, Rome, Italy) The June 1 issue of Nature has several papers on basic science aspects of AIDS. One question of interest is the origin of the HIV virus. A report and a brief review describe evidence—not yet totally convincing—for recent movement of the virus from a monkey source to man. R.F Doolittle, "The simian-human connection," Nature, 339, 338-9, 1 June 1989 (University of California, La Jolla) V.M. Hirsch, R.A. Olmsted, M. Murphey-Corb, R.H. Purcell, P.R. Johnson, "An African primate lentivirus (SIVsm closely related to HIV-2,"Nature, 339, 389-92,1 June 1989. (Georgetown University, NIH/Twinbrook II, Rockville, Md.; Delta Regional Primate Research Center, Tulane University, Covington, La.; National Institutes of Health, Bethesda, Md.) Efflux pumping is the mechanism of resistance for the "multidrug resistance" system determined by the P-glycoprotein of mammalian tumor cells. Now gene "fishing" in two laboratories has isolated homologous genes responsible for drug resistance of the malarial parasite. C.M. Wilson, A.E. Serrano, A. Wasley, M.P. Bogenschutz, et al., "Amplification of a gene related to mammalian mdr genes in drug-resistant Plasmodium falciparum," Science, 244, 1184-6,9 June 1989. (Harvard School of Public Health, Boston, Mass.)S.J. Foote, J.K. Thompson, A.F. Cowman, D.J. Kemp, "Amplification of the multidrug resistance gene in some chloroquine-resistant isolates of P. falciparum," Cell, 57, 921-30, 16 June 1989. (Walter: and Eliza Hall Institute of Medical Research, Victoria, Australia) The cover of the June 16 issue of Science promises "The New Harvest: Genetically Engineered Species," With an illustration of presumably "better" crops and livestock sprouting from DNA in a test tube, and insect pests about to be killed by toxins made from bacterial genes cloned into the plant hosts of the insects. Three articles are presented. C.S. Gasser, R.T. Fraley, "Genetically engineering plants for crop improvement," Science, 244, 1293-9, 16 June 1989. (Monsanto Co., St. Louis, Mo.)V.G. Pursel, C.A. Pinkert, K.F. Miller, D.J. Bolt, et al., "Genetic engineering of livestock," Science, 244, 1281-8, 16 June 1989. (U.S. Department of Agriculture, Beltsville, Md.; University of Pennsylvania, Philadelphia; etc.)S.E. Lindow, N.J. Panopoulos, B.L. McFarland, "Genetic engineering of bacteria from managed and natural habitats," Science, 244, 1300-7, 16 June 1989. (University of California, Berkeley; Chevron Research Company, Richmond, Calif.) PLANT AND ANIMAL SCIENCES BY PETER D. MOOREDepartment of Biology King's College London, U.K. Soil acidification affects not only plants, but also the soil fungi, many of which enter into a mutually profitable association with higher plants via mycorrhizas. Experimental acidification of soils over a five-year period resulted in a failure to form this association below pH 4 for timothy grass and below pH 3.3 for lodgepole pine. The growth of both these economically important plants is consequently impaired. R.M. Danielson, S. Visser, "Effects of forest soil acidification on ectomycorrhizal and vesicular-arbuscular mycorrhizal development," New Phytologist, 112, 41-47, May 1989. (University of Calgary, Alberta, Canada) The introduced European rabbit population of Australia varies considerably in body form with its range. Animals from warmer regions tend to have leaner bodies and longer ears, which .are phenotypic responses to environment and genetic variation, as well as the serendipity of the "founder effect"—that is, the genetic constitution of the original colonists .... C.K. Williams, R.J. Moore, "Phenotypic adaptation and natural selection in the wild rabbit, Oryctolagus cuniculus in Australia," Journal of Animal Ecology, 58,495-507, June 1989. (CSIRO, Lyneham, Australia) Variations in phytoplankton diversity among small lakes in Switzerland showed highest diversity where nutrients were most scarce and grazing pressures greatest. Variations in diversity during the year were a consequence of changes in the nutrients' status in the lake waters, often resulting from organic pollution. F. Elber, F. Schanz, "The causes of change in the diversity" and stability of phytoplankton communities in small lakes," Freshwater Biology, 21, 237-51, April 1989. (Universität Zurich, Kilchberg, Switzerland) The eruption of Krakatau in 1883 provided an opportunity for ecologists to follow the course of recolonization. Recent surveys have now brought the story up to date and show that 50 years after the establishment of a full forest canopy, the vegetation remains species-poor, though forest ferns are still invading. Extinctions are taking place among the original pioneer species, but newcomers continue to arrive. R.J. Whittaker, M.B. Bush, K. Richards, "Plant recolonization and vegetation succession on the Krakatau Islands, Indonesia," Ecological Monographs/59, 59-123, June1989. (Universities of Oxford and Hull, U.K.; Robertson Research International, Llandudno, Wales)

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