Editors' Choice

Science  30 Sep 2005:
Vol. 309, Issue 5744, pp. 2138

    Getting Oriented

    1. Stella M. Hurtley

    When cells within tissues divide, the orientation of the mitotic spindle defines the position of the daughter cells and thereby dictates cell fate. Théry et al. explored the relative effects of cell geometry and extracellular cues on how mammalian cells orient their division axis in vitro. Cells adhered to the substrate via interactions with the extracellular matrix (ECM), and the authors used micro-contact printing to lay down the ECM component fibronectin in well-defined patterns. By looking at how cells spread and divided on these surfaces, the authors found that the spatial organization of the ECM influences via retraction fibers the dynamics of the actin cytoskeleton, which then specifies the orientation of the division axis. This system can be manipulated to look at other regulatory inputs onto spindle orientation and hence daughter cell positioning, which may be useful in tissue engineering and device design. — SMH

    Nat. Cell Biol. 10.1038/ncb1307 (2005).


    It's Not Just in Your Mind

    1. Gilbert J. Chin

    The links between psychology and immunology have, for the most part, either been dismissed as a collection of anecdotes or avoided as being too nebulous to study in a controlled fashion. The consequences have been a persistent interest in folk science and a dearth of solid mechanistic evidence.

    Rosenkranz et al.have brought modern neuroimaging techniques to bear on this problem and identify neural substrates where the state of the body makes itself known to the mind. Six asthmatic patients were challenged with allergens (cat dander and dust mites), and the subsequent development of early-phase (mast cell degranulation) and late-phase (T cell cytokine release) airway constriction was measured by forced expiratory volume and sampling of sputum and blood after 1 and 4 hours, respectively. Concurrently, the neural responses to asthma-related words were assessed by brain scans. Under these conditions, activity (specifically associated with words such as wheeze) in the insula and the anterior cingulate cortex correlated with the extent of late-phase allergic inflammation, suggesting that physiological stress can influence the cognitive processing of emotionally potent stimuli. — GJC

    Proc. Natl. Acad. Sci. U.S.A. 102, 13319 (2005).


    Sex Doesn't Pay for Females

    1. Guy Riddihough

    In the battle of the sexes—also known as sexually antagonistic coevolution—it is the female who loses. For instance, in Drosophila, males harm females during both courtship and mating. But are there hidden benefits for females; that is, do they endure the injury of multiple mating to benefit their offspring? And could such benefits compensate for the direct costs of mating?

    Stewart et al.address the latter question in Drosophila by creating an artificial selection system that protects females from the cost of injury by males, but also robs them of any indirect advantages. A population of red- and brown-eyed females were briefly mated, and the nonvirgin flies were separated, so that the red-eyed females were subsequently exposed to a low density of harassing males (1:8, male:female) and the brown-eyed flies were exposed to a high density of males (1:1). Progeny from these crosses were collected and counted for eye color, and the experiment was repeated for five generations. The frequency of the red-eye “male resistance” allele increased substantially, showing that the indirect benefits of multiple mating (being able to trade up for a better mate) fail, by a considerable margin, to outweigh the harm inflicted. So why hasn't a real male resistance allele appeared? The authors speculate that males stay ahead of females in the sexual arms race and that females cannot anticipate male adaptations. — GR

    Proc. R. Soc. London Ser. B 10.1098/rspb.2005.3182 (2005).


    A Miniature Clock Factory

    1. Ian S. Osborne

    The combination of developments in microfabrication and precision spectroscopy of confined atomic gases has promised to benefit applications in timing metrology, where the requirements of low cost and small size along with long-term stability are paramount. However, earlier work on chip-sized atomic clocks has shown that chemical reactions in the gas cell, resulting from the presence of impurities and byproduct gases from the cell fabrication and gas-filling processes, lead to long-term drift in the clock frequency.

    Knappe et al.have devised a fabrication and cell-filling technique that removes much of the contaminant gas from the cell, and they show that the frequency stability can be improved by several orders of magnitude to a drift of no more than 5 × 10−11 per day. The improvement suggests chip-scale atomic clocks as a viable technology in applications where better precision than that available in quartz-based clocks is desired. — ISO

    Opt. Lett. 30, 2351 (2005).


    Winter Advisory

    1. H. Jesse Smith

    Fresh water is one of the most important resources and is vital for humans, agriculture, and natural ecosystems. There are many threats to the supply of this commodity, including climate change; pollution by industrial, agricultural, and automotive wastes; and overuse. Kaushal et al.add another: road salt.

    Road salt is used liberally in areas of the northeastern United States that receive appreciable amounts of snow, and the runoff into urban and suburban watersheds is a growing threat to fresh water reserves. By measuring the concentration of chloride in streams in Maryland, New York, and New Hampshire during winters, the authors show that salinities are approaching 25% that of seawater in some cases and are greater than 100 times that of pristine forest streams during summers. Watersheds where roads are densest are under severe pressure. If salinity in these regions continues to increase, surface water supplies in the Northeast may become unfit for human consumption and toxic to freshwater organisms by the end of the century. — HJS

    Proc. Natl. Acad. Sci. U.S.A. 102, 13517 (2005).


    The Value of a Nickel

    1. Jake S. Yeston

    Ethylene and other terminal olefins are produced inexpensively and in large quantities from petroleum and can be used directly as electrophiles in reactions for making pricey chemicals. However, to use olefins as nucleophiles, it's generally necessary to transform them into air-sensitive lithium or magnesium organometallics.

    Ng and Jamison have developed a homogeneous nickel catalyst for the direct addition of terminal olefins to aldehyde electrophiles, which leads to synthetically useful allylic alcohols without the need for metallation. The key to the catalyst is a hindered arylphosphine ligand. High yields are obtained at room temperature for the addition of ethylene to aromatic or tertiary alkyl aldehydes, coupled with silylation of the resulting alcohol by triethylsilyl triflate and quenching of the triflic acid byproduct by an amine base. The reaction also works for alkyl-substituted olefins, albeit with a drop in yield, and regioselectively affords the geminal addition product. The authors speculate that the mechanism involves a five-membered Ni-metallacycle intermediate. — JSY

    J. Am. Chem. Soc. 10.1021/ja055363j (2005).

  7. STKE

    Unmixing Memory and Desire

    1. Elizabeth M. Adler

    Recovering drug addicts often relapse after exposure to environmental or contextual cues that are associated with drugs. In a rat model system, the acquisition of cocaine-conditioned place preference (COC-CPP) depends on activation of the extracellular signaling-regulated kinase (ERK); it is blocked by inhibiting mitogen-activated protein kinase kinase (MEK), which normally phosphorylates and activates ERK. Miller and Marshall show increased phosphorylation of ERK in the nucleus accumbens core (AcbC, a midbrain region associated with cue-elicited drug seeking) in rats that had acquired COC-CPP. Infusion of a MEK inhibitor into the AcbC shortly before testing blocked COC-CCP-related behavior and the associated increase in ERK phosphorylation. Furthermore, rats that received a MEK inhibitor right after passing the test failed to exhibit COC-CCP when retested later and showed decreased activation of the AcbC ERK pathway. Thus, the authors conclude that disruption of memory reconsolidation blocks the expression of COC-CCP. Expression of the transcription factor Zif268 in the amygdala increases after reexposure to stimuli associated with self-administration of cocaine. In the study by Lee et al., rats learned to associate a light with a cocaine infusion; the association is so potent that the light acquires a reward value of its own and supports instrumental learning. When paired with a memory reactivation session, Zif268 antisense DNA infused into the basolateral amygdala eliminated the ability of light to promote acquisition of a new behavior. — EMA

    Neuron 47, 873; 795 (2005).

Log in to view full text

Via your Institution

Log in through your institution

Log in through your institution