Editors' Choice

Science  09 Jan 2009:
Vol. 323, Issue 5911, pp. 186

    Vaccine Takes a Toll

    1. Paula A. Kiberstis

    Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in infants, and early exposure to the virus is thought to confer an increased risk of wheezing and asthma later in life. Efforts to develop a protective vaccine suffered a major setback in the 1960s when a formalin-inactivated vaccine against RSV (FIRSV) not only failed to protect against viral infection, but severely exacerbated lung disease in vaccinated infants and children, many of whom required hospitalization. Forty years later, Delgado et al. offer a fresh perspective on why the FIRSV vaccine may have failed. Studying the immune responses in mice treated with wild-type RSV or with either of two inactivated vaccines [FIRSV or a vaccine inactivated by ultraviolet light (UVRSV)], they found that both inactivated vaccines elicited short-lived antibodies that were nonprotective. Further experiments with UVRSV revealed that these antibodies had a low affinity for crucial viral antigens and that this was due to deficient activation of Toll-like receptor (TLR) signaling in B cells. Mice that had been treated with both UVRSV and TLR agonists and then infected with RSV had lower levels of virus and milder lung disease than mice treated with the vaccine alone. These results cast doubt on an earlier hypothesis attributing the vaccine failure to formalin-mediated disruption of viral antigens, and they raise the possibility that agents stimulating the TLR pathway may enhance the efficacy of future candidate vaccines. — PAK

    Nat. Med. 10.1038/nm.1894 (2008).


    Reaching Out to the Other Side

    1. Nancy R. Gough

    Epithelial cells line the surfaces of the body, either in monolayers (simple) or in multiple layers (stratified). A third type of arrangement, referred to as pseudostratified, contains only a single layer of cells, but with their nuclei dispersed so as to give a laminated appearance. Shum et al. have used cell-specific labeling, confocal microscopy, and three-dimensional reconstruction to show that in pseudostratified epithelia, basal cells (on which the epithelium sits) extend projections that infiltrate the epithelial cell layer to make contact with the other (lumenal) surface. Such cells were observed in epididymis (both rat and human), rat coagulating gland (similar to the prostate), and rat trachea. Detailed analysis of the rat epididymis revealed that the frequency of these projections varied, with less than 10% of basal cells exhibiting this trait in proximal vas deferens and about 60% extending toward the lumen in more distal regions. The morphology of these projections varied, with some appearing just beneath tight junctions and some passing through the tight junctions at which three epithelial cells met. The authors detected angiotensin type 2 receptors (the renin-angiotensin system regulates male fertility) only in the basal cells (shown at left, green), and not in the clear cells (red) that acidify the lumen and keep sperm dormant during maturation and storage. Perfusion of rat epididymis with angiotensin II triggered the extension of proton pump-enriched microvilli from the clear cells and stimulated proton secretion. Thus, the authors suggest that the lumenal projections of the basal cells serve as sensors of hormones and transmit signals to neighboring cells within the epithelium. — NRG*

    Cell 135, 1108 (2008).

    • *Nancy R. Gough is Editor of Science Signaling.


    Queen of Decay

    1. Caroline Ash

    Osedax (shown above) is a recently discovered annelid worm that, with a little help from endosymbiotic bacteria called Oceanospirillales, feeds on the bones of whales. However, whale carcasses are rare, and the diversity of Osedax species astonishing, so how these organisms persist and scatter is a conundrum. Rouse et al. have set out to elucidate the life-history peculiarities of worms feasting on whale carcasses planted at defined depths in Monterey Bay, California.

    Male worms are parasitic on females, and thus fertilization is guaranteed. Moreover the animals are highly fecund, with females devoting a large proportion of their body mass to ovary, whereas the male's somatic development is sidetracked into sperm production, possibly by signals from the females; under laboratory conditions, they seem to reproduce continuously. It appears that the metamorphosis of females from a swimming trochophore only occurs when the larvae encounter a carcass and have been infected with the endosymbiont. These tactics concur with the obvious ecological needs of these strange worms, but how long the larvae live, whether they have searching strategies, and how far they disperse are interesting questions that still await answers. — CA

    Mar. Biol. 10.1007/s00227-008-1091-z (2008).


    Reactive Channels

    1. Marc S. Lavine

    Coordination polymers consist of metal centers strung together by multiple ligands, often to form a porous framework material that can encapsulate molecular guests. For many coordination polymers, a change in the oxidation state of the metal leads to a collapse of the framework structure. One exception is a layered material based on [FeIII(CN)6]3− units, which is structurally stable to reduction because the reduced [FeII(CN)6]4− groups retain a similar coordination geometry. Yanai et al. have exploited this property by infiltrating the framework with pyrrole monomers, which are then oxidized and polymerized by the iron within well-defined channels. Addition of the chelator ethylenediamine tetraacetic acid cleanly dismantles the framework to liberate the polypyrrole. Whereas bulk polypyrrole has a granular morphology, the polypyrrole grown inside the coordination polymer (shown above) exhibited an overlapping plate structure made up of discernible stacks of thin layers. After the product was doped with iodine, the conductivity along the direction parallel to the plates was 20 times as high as that perpendicular to the plates, confirming the orienting impact of the iron host and catalyst framework. — MSL

    Angew. Chem. Int. Ed. 47, 9883 (2008).


    Budding Blood Cells

    1. Beverly A. Purnell

    Arguably the best-understood stem cells are those that generate the body's blood cells—hematopoietic stem cells (HSCs). Although the place of origin, the aortic-gonado-mesonephric (AGM) columns, is known, the specific cell type responsible for their emergence is not. By labeling cell populations in vivo either with the adhesion molecule VE cadherin or the transcription factor myocardin, Zovein et al. were able to follow endothelial and mesenchymal progeny, respectively. Their data point to an endothelial origin of HSCs for subsequent long-term, multilineage adult hematopoiesis. Further, the HSC endothelial progeny could be monitored as they traveled first to the fetal liver and then to the bone marrow for subsequent expansion and multilineage differentiation. Besides the AGM region, the authors also identified the placental vasculature and yolk sac as endothelial sources of HSCs. Hence, the origin of hematopoietic stem cells is endothelium, which itself comes from a transient mesenchymal population of cells. — BAP

    Cell Stem Cell 3, 625 (2008).


    Bee Raves

    1. Laura M. Zahn

    Cocaine triggers reward pathways in the human brain and is toxic at high doses; it is postulated to have evolved as an insecticide that protects the coca plant. Barron et al. have tested the response of honey bees to cocaine and find suggestive evidence of a reward effect at low doses. By examining the honey bee dance—the means by which bees signal the availability of resources to their hive-mates—they found that dosing the bees with cocaine increased both the likelihood and rate of dance after foraging; furthermore, the bees exhibited behavior consistent with a withdrawal effect when the drug was withheld after chronic treatment. The authors conclude that responsiveness and signaling in the appropriate settings were increased by the treatment with cocaine, suggesting that the response to the drug may be similar in humans and bees. — LMZ

    J. Exp. Biol. 212, 163 (2009).


    Holey Different Films

    1. Phil Szuromi

    Surface plasmon-polaritons (SPPs) are generally studied in noble metals. The problem in observing coupling of SPPs to the magnetic field effects in ferromagnetic metals is that absorption broadens out the anticipated magneto-optical signatures. Ctistis et al. prepared cobalt films (50 to 100 nm thick) that contained a hexagonal array of nanoholes (diameters between 220 and 330 nm and with a spacing of 470 nm). The presence of the holes changed the magnetic properties of the film in two ways—it increased the coercive field in the in-plane directions and created magnetization components out-of-plane. Light transmission through these films depended on the external magnetic field through the excitation of SPPs. The films showed higher polarization rotation than a continuous cobalt film, and the enhancement occurred at the wavelength maxima of the SPPs. — PDS

    Nano Lett. 10.1021/nl801811t (2008).