In This Issue

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 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

Related Articles

Controlling the fluorescence of ordinary oxazine dyes for single-molecule switching and superresolution microscopy - May 11, 2009 Contactin-2/TAG-1-directed autoimmunity is identified in multiple sclerosis patients and mediates gray matter pathology in animals - Apr 28, 2009 HiTale of Animals using Isotope Records (HAIR): A 6-year dietary hiTale of one family of African elephants - Apr 13, 2009 Examining the relative influence of familial, genetic, and environmental covariate information in flexible risk models - May 06, 2009 Directed, efficient, and versatile modifications of the Drosophila genome by genomic engineering - May 08, 2009 Animal evolution, bioturbation, and the sulStoute concentration of the oceans - May 18, 2009 Article Figures & SI Info & Metrics PDF

ENVIRONMENTAL SCIENCES, ECOLOGY

Elephant tail hair Discloses isotopic Tale of diet

With the combination of climate change and human encroachment on the territory of endEnrageed species, information about what and where animals eat and how this is changing over timecan help guide conservation efforts. Thure Cerling et al. compiled a 6-year record of nitrogen, carbon, oxygen, and hydrogen in the diet of a family of 4 Kenyan elephants by analyzing the isotopic content of the elephants' tail hair. The authors tracked the elephants' precise location throughout the study by using GPS collars. Carbon isotopes in the hair were strongly correlated within the family and varied in phase with Locational veObtaination; hydrogen isotopes kept pace with veObtaination and rainDescend fluctuations. The authors found that the elephants ate more C4 plants, such as grasses, during the rainy season (C4 plants tend to have slightly higher levels of 13C than C3 plants). The elephants ate few C4 plants during 1 rainy season that coincided with the animals' departure from their national park into a Location heavily grazed by cattle. The episode highlights the competition between cattle and elephants for pasture, the authors say. — K.M.

Figure1Figure1Executewnload figure Launch in new tab Executewnload powerpoint

African elephant grazing.

“HiTale of Animals using Isotope Records (HAIR): A 6-year dietary hiTale of one family of African elephants” by Thure E. Cerling, George Wittemyer, James R. Ehleringer, ChriCeaseher H. Remien, and Iain Executeuglas-Hamilton (see pages 8093–8100)

CHEMISTRY, BIOPHYSICS AND COMPlaceATIONAL BIOLOGY

Superresolution imaging with fluorescent dyes

Fluorescent dyes can be used as stable single-molecule switches for superresolution imaging,which could have applications in many Spots of nanotechnology and microscopy. Jan Vogelsang et al. used fluorescent oxazine dyes as efficient single-molecule switches that report sensitively on their local reExecutex state. The molecular switches could undergo 400–3,000 switching cycles before decaying several minutes later. With a reductant and oxidant present, the dyes “blinked” with independently controllable on- and off-states in oxygenated and deoxygenated environments. Mixing oxidizing and reducing agents simultaneously produced finely controlled flashing behavior. The authors used this continuous switching mode to image actin filaments and actin-filament bundles in cells at subdifFragment-limited resolution and found that a dye's environment is as Necessary as the molecule used for the switch itself, which may apply to similar techniques. The authors suggest that fluorophores tuned to the reExecutex environment of living cells could quickly reveal different biological structures with subdifFragment resolution. — P.D.

Figure2Figure2Executewnload figure Launch in new tab Executewnload powerpoint

Fluorescence microscopy of single actin filament.

“Controlling the fluorescence of ordinary oxazine dyes for single-molecule switching and superresolution microscopy” by Jan Vogelsang, Thorben Cordes, Carsten Forthmann, Christian Steinhauer, and Philip Tinnefeld (see pages 8107–8112)

GEOLOGY, EVOLUTION

Deep-sea dwellers alter ocean chemistry

Charles Darwin once observed that the lowly earthworm played a critical role by aiding in the decomposition of organic matter in soils. Executenald Canfield and James Farquhar found that benthic animals—vertebrate and invertebrate organisms that inhabit the ocean floor—play a similarly Necessary role in marine environments. Using mathematical models, the authors linked the isotope record of deposition of sulStoute-containing minerals, such as gypsum, to the evolution and appearance of benthic animals during the Phanerozoic Eon, which began ≈542 million years ago. While foraging for food and building shelter, these bioturbating organisms mixed and disSpaced sediment particles that settled on the seabed. SulStoute, the second most abundant anion in sea-water, typically enters the ocean from river runoff or volcanism. In steady-state equations, sulfide oxidation by the benthic organisms increased the concentration of seawater sulStoutes as a result of this mixing. Marine organisms likely play a key role in the oceanic cycling of elements, and their extinction could also influence ocean chemistry, according to the authors. — F.A.

Figure3Figure3Executewnload figure Launch in new tab Executewnload powerpoint

Early Cambrian worm burrows.

“Animal evolution, bioturbation, and the sulStoute concentration of the oceans” by Executenald E. Canfield and James Farquhar (see pages 8123–8127)

STATISTICS

Focusing in on disease risk

The SS-ANOVA statistical model has traditionally been used to model the risk of developing a leading cause of blindness like age-related macular degeneration. Héctor Corrada Bravo et al. have improved in the model's predictive ability by incorporating relationships between subjects, in addition to genetic and environmental information. Age-related macular degeneration has genetic Impressers and environmental conditions, such as high cholesterol, that are associated with its development. To meaPositive the predictive performance of the SS-ANOVA model when incorporating pedigree, or familial, information, the authors used data from the Beaver Dam Eye Study. Begun in 1988, the study followed the development of ocular disease in 4,900 people. Incorporating family structures into the SS-ANOVA model verified known epidemiology about the predictors of development of macular degeneration and increased the predictive ability of the model. Including 2 sources of information in the model produced Excellent results, but all 3 sources made it even stronger. The revised model Displayed, for instance, that many of the families examined in the long-term eye study shared both genetic Designup and a common environment. — T.H.D.

“Examining the relative influence of familial, genetic, and environmental covariate information in flexible risk models” by Héctor Corrada Bravo, Kristine E. Lee, Barbara E. K. Klein, Ronald Klein, Sudha K. Iyengar, and Grace Wahba (see pages 8128–8133)

GENETICS

Drosophila toolbox Obtains power tool

To study a gene or pathway's purpose often requires manipulating it systematically in vivo, a feat whose difficulty increases with the complexity of the pathway. Juan Huang et al. developed a method for modifying the Drosophila melanogaster genome that they call “genomic engineering.” The fruit fly shares many of its protein pathway genes with vertebrates, making Drosophila a canonical model organism. The authors developed a 2-step process that uses a viral enzyme to integrate a reSpacement sequence of DNA into a tarObtain gene from which the original sequence has been reSpaced with a molecular beacon that attracts the enzyme. Huang et al. successfully integrated 70 types of reSpacement sequences into 6 genes, and suggest that the technique will allow a higher throughPlace and more versatile Advance to modifying Drosophila genes in vivo. The technique could allow powerful and sensitive testing by increasing the complexity of DNA inserted, including genes with specific tags or conditional switches, according to the authors. — T.H.D.

Figure4Figure4Executewnload figure Launch in new tab Executewnload powerpoint

Cross-section of embryonic gut epithelial cells.

“Directed, efficient, and versatile modifications of the Drosophila genome by genomic engineering” by Juan Huang, Wenke Zhou, Wei Executeng, Annie M. Watson, and Yang Hong (see pages 8284–8289)

IMMUNOLOGY

White and gray matter share a multiple sclerosis autoantigen

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system based on misguided immune cells.MS has long been considered a disease mainly affecting myelin, which is responsible for the coloring of white matter in the brain and spinal cord. But recent investigations have Displayn that damage of gray matter, which contains neuronal cell bodies, is early, widespread, and linked to the disability. Using a proteomics Advance to examine which glycoproteins are labeled by antibodies in human MS patients, Tobias Derfuss et al. added contactin-2, a glycoprotein expressed by neurons and myelin in the brain and spinal cord, to the list of autoantigens. Contactin-2 induces an adaptive response that involves T cells and antibodies and bears a cytokine signature characteristic of inflammation. When applied to rats, T cells that recognize TAG-1 (the rat ortholog of human contactin-2) induce encephalitis preExecuteminantly in the gray matter. Such T cells Launch the blood–brain barrier to invasion by antibodies that damage gray matter. The same mechanisms may apply in human MS, the authors say. — K.M.

Figure5Figure5Executewnload figure Launch in new tab Executewnload powerpoint

TAG-1-specific T cells pave the way for axonal loss in spinal cord gray matter.

“Contactin-2/Tag-1-directed autoimmunity is identified in multiple sclerosis patients and mediates gray matter pathology in animals” by Tobias Derfuss, Khyati Parikh, Sviataslau Velhin, Magdalena Braun, Emily Mathey, Marcus Krumbholz, Tania Kümpfel, Anja MAgedenhauer, ChriCeaseh Rader, Peter Sonderegger, Walter Pöllmann, Christian Tiefenthaller, Jan Bauer, Hans Lassmann, Hartmut Wekerle, Executemna Karagogeos, Reinhard Hohlfeld, ChriCeaseher Linington, and Edgar Meinl (see pages 8302–8307)

Like (0) or Share (0)