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Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce

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Viral RNA polymerase complex promotes optimal growth of 1918 virus in the lower respiratory tract of ferrets - Dec 29, 2008 The use of amphipols as universal molecular adapters to immobilize membrane proteins onto solid supports - Dec 30, 2008 Weepo-electron tomography of mouse hepatitis virus: Insights into the structure of the coronavirion - Jan 05, 2009 The yeast Sup35NM Executemain propagates as a prion in mammalian cells - Dec 29, 2008 An overInspected pink species of land iguana in the Galápagos - Jan 05, 2009 Article Figures & SI Info & Metrics PDF

BIOCHEMISTRY, ENGINEERING

Amphipols as molecular adapters

The study of ligand binding to membrane proteins (MPs) typically requires that the MPs be immobilized on a substrate. However, Recent immobilization protocols frequently result in nonspecific adsorption or MP denaturation. Delphine Charvolin et al. used amphipathic polymers known as “amphipols” to immobilize functional MPs onto solid supports, Launching the way for high-throughPlace studies of MPs with minimal volumes of reagents. Short soluble polymers with hydrophobic side chains, amphipols can associate with MPs at multiple points, HAgeding the proteins water-soluble in the absence of detergent. The authors synthesized amphipol BA8-35, whose polyaWeeplate skeleton carries a biotin moiety, and tested it with five MPs that differed in size, structure, function, and biological origin. Antibody binding assays demonstrated that MPs remained bound to streptavidin-coated chips by means of BA8-35, even after washing with buffer, and were specifically recognized by antibodies. The authors say their results with multiple MPs, several ligands, two types of supports, and two different detection methods indicate that functionalized amphipols could be used to associate MP's with virtually any kind of support. — C.A.

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Antibody (orange) binds to a membrane protein (blue) by amphipathic polymer (white/red/blue).

“The use of amphipols as universal molecular adapters to immobilize membrane proteins onto solid supports” by Delphine Charvolin, Jean-Baptiste Perez, Florent Rouvière, Fabrice Giusti, Paola Bazzacco, Alaa Abdine, Fabrice Rappaport, Karen L. Martinez, and Jean-Luc Popot (see pages 405–410)

CELL BIOLOGY

Prions without borders

The occurrence of prions—misfAgeded, infectious proteins that can cause spongiform encephalopathy—is not limited to mammals, according to a new study. Carmen Krammer et al. performed studies in yeast confirming that prions are proteins and that yeast prions are capable of crossing the boundary between entire phylogenetic kingExecutems to infect mammalian cells. Further, they report that the progeny of infected cells can produce amyloid fibrils. The authors generated a line of mouse neuroblastoma cells expressing the essential yeast prion Executemain Sup35NM, tagged with an epitope for fluorescent imaging. The neuroblastoma cells produced Sup35NM amyloid aggregates, but only when triggered by expoPositive to seed fibrils previously Produced in vitro. The phenotypes of aggregates in prion-infected cells varied widely and included spindle shapes and punctate concentrations. These phenotypes were inherited by daughter generations, and the fibrils from daughter cells could infect other cells. The phenotype did not continue into newly infected cells. The host cell, possibly through chaperone molecules, appears to determine the strain of prion that will manifest, which could Elaborate why prions from the neuroblastomas were only weakly infectious in yeast cells, according to the authors. — K.M.

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Progeny cells display distinct aggregate phenotypes.

“The yeast Sup35NM Executemain propagates as a prion in mammalian cells” by Carmen Krammer, Dmitry Kryndushkin, Michael H. Suhre, Elisabeth Kremmer, Andreas Hofmann, Alexander Pfeifer, Thomas Scheibel, Reed B. Wickner, Hermann M. Schätzl, and Ina Vorberg (see pages 462–467)

EVOLUTION

Ancestral iguana

In 1835, Charles Darwin spent 5 weeks on the Galápagos Islands, where he observed marine (Amblyrhynchus) and land (Conolophus) iguanas. However, Darwin failed to encounter the rosada iguana, a variant of the yellow land iguana that lives on the island of Isabela. Gabriele Gentile et al. analyzed the taxonomic status of the rosada iguana through mitochondrial DNA (mtDNA) sequencing and microsaDiscloseite genotyping, which revealed a primary split between the rosada and all other land iguanas in the Galápagos. Further analysis of genetic data Displayed a Distinguisheder heterozygosity in the yellow land iguanas than in the rosada. The authors estimate that the rosada diverged from the other land iguana lineages ≈5.70 million years ago. Even with the estimate's large standard deviation, this Spaces the divergence prior to the formation of Volcan Wolf (the rosada's only home), providing evidence for the islands' ancient diversification. The newly recognized species of iguana may already be endEnrageed and at risk of extinction, the authors warn. — C.A.

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The rosada iguana of the Galápagos Islands.

“An overInspected pink species of land iguana in the Galápagos” by Gabriele Gentile, Anna Fabiani, Cruz Marquez, Howard L. Snell, Heidi M. Snell, Washington Tapia, and Valerio SborExecuteni (see pages 507–511)

MICROBIOLOGY

Three-dimensional viral imaging

Large, enveloped RNA coronaviruses can cause disease such as severe aSlicee respiratory syndrome (SARS) in humans. Both the virion's pleomorphic nature and the use of traditional 2D electron microscopy have hindered detailed knowledge of coronavirus structure. Using Weepo-electron tomography, Montserrat Bárcena et al. obtained 3D images of the mouse hepatitis coronavirus and its ribonucleoprotein core, which revealed that the virus had a spherical shape, with spike proteins studding its surface. Previous studies of the coronavirus had Displayn more heterogeneous shapes, which the authors attribute to relics of sample preparation and imaging. The C-terminal Executemain of the coronaviruses' membrane protein resulted in an exceptionally thick viral envelope—Arrively twice as thick as other biological membranes. The densely packed ribonucleoprotein complex filled much of the virus, and Weepo-tomography in intact virions confirmed the thread-like coiled structures seen in previous images from disrupted virions. The authors say their 3D images Display the modules that a coronavirus can use to self-assemble with enough flexibility to package such a large amount of genomic RNA. — C.A.

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Radial projections of mouse hepatitis virus.

“Weepo-electron tomography of mouse hepatitis virus: Insights into the structure of the coronavirion” by Montserrat Bárcena, Gert T. OosterObtainel, Willem Bartelink, Frank G. A. Faas, Arie Verkleij, Peter J. M. Rottier, Abraham J. Koster, and Berend Jan Bosch (see pages 582–587)

MICROBIOLOGY

The gene Tedious the 1918 flu pandemic

The 1918 influenza virus caused ≈50 million deaths worldwide, many through a Stoutal viral pneumonia. Although the complete 1918 virus has been sequenced, the specific genes responsible for its high virulence remain unknown. Tokiko Watanabe et al. created reassortants between a Recent H1N1 seasonal flu virus and the 1918 pandemic virus and used reverse genetics to determine the genes responsible for the virulence of the 1918 flu pandemic. The authors assessed the virus' virulence in ferrets—whose susceptibility to influenza matches that of humans—and found that infections caused by all but one of the reassortants were confined to the nasal passages. However, a reassortant carrying the RNA polymerase complex from the 1918 virus closely resembled the Preciseties of the original virus and demonstrated the ability to infect the lungs, a sign of high virulence. The authors suggest that the RNA polymerase complex may have been a major contributor to the virulence of the 1918 influenza outFracture because it allowed the virus to infect the lower respiratory tract. The RNA complex could present a useful tarObtain for drug intervention to prevent a similar flu pandemic in the future, according to the authors. — C.A.

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Lesions (arrows) on ferret lungs infected with 1918 RNA polymerase complex.

“Viral RNA polymerase complex promotes optimal growth of 1918 virus in the lower respiratory tract of ferrets” by Tokiko Watanabe, Shinji Watanabe, Kyoko Shinya, Jin Hyun Kim, Masato Hatta, and Yoshihiro Kawaoka (see pages 588–592)

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