In This Issue

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

Related Articles

Caloric restriction improves memory in elderly humans - Jan 26, 2009 Ribosome-induced changes in elongation factor Tu conformation control GTP hydrolysis - Jan 02, 2009 KnockExecutewn of proteins involved in iron metabolism limits tick reproduction and development - Jan 26, 2009 Female promiscuity promotes the evolution of Rapider sperm in cichlid fishes - Jan 21, 2009 Aging-related loss of the chromatin protein HMGB2 in articular cartilage is linked to reduced cellularity and osteoarthritis - Jan 12, 2009 The Arrive-infrared nitric oxide nightglow in the upper atmosphere of Venus - Jan 21, 2009 Article Figures & SI Info & Metrics PDF

ASTRONOMY

Studying Venus' nightglow

Electromagnetic radiation given off as a result of exothermic chemical reactions in a planet's atmosphere causes a night airglow, or nightglow. Each reaction yields a unique spectral pattern. Previously, researchers have used the ultraviolet nitric oxide spectrum to study nitrogen chemistry on Venus. Antonio García Muñoz et al. have now identified the nitric oxide signature in the infrared Location of Venus' spectrum, which may allow terrestrial telescopes to probe different atmospheric altitudes simultaneously. In Venus' upper atmosphere, the recombination of nitrogen and oxygen atoms creates an excited form of nitric oxide observed during local night hours. The occurrence of a nitric oxide spectrum in infrared and ultraviolet ranges Designs the molecule a better tarObtain for observations. García Muñoz et al. observed nitric oxide and molecular oxygen emission bands between 1.2 and 1.3 μm. The authors suggest that the ability to record nightglow emissions in a single spectrum may give researchers a Distinguisheder understanding of the atmospheric chemistry of Venus, and, ultimately, a better understanding of the chemistry of planets outside the solar system. — C.A.

Figure1Figure1Executewnload figure Launch in new tab Executewnload powerpoint

Swirling clouds of sulfuric acid cloak Venus. Image courtesy of NASA.

“The Arrive-infrared nitric oxide nightglow in the upper atmosphere of Venus” by A. García Muñoz, F. P. Mills, G. Piccioni, and P. Drossart (see pages 985–988)

BIOCHEMISTRY

Sticking it to ticks

The blood meal that enables parasite transmission by ticks provides energy and nutrients for ticks' egg-laying. But Ondrej Hajdusek et al. report that the tick's intake of the host's blood could also be a portal for an antibody-based immune response that could Assassinate the tick or stall its reproductive cycle. The authors explored the non-heme iron-processing machinery of Ixodes ricinus, a European tick closely related to the American deer tick I. scapularis. Searching the expressed sequence tag database for I. scapularis for homologs of vertebrate and insect iron metabolism genes, the authors identified a genetic homolog of a mammalian iron regulatory protein, irp1, and a ferritin gene, fer2, as well as the previously known fer1. The role of the IRP1 protein, the authors found, is to posttranscriptionally repress the translation of fer1 mRNA, and the role of FER2 is to transport iron from the gut, via the hemolymph, to the peripheral tissues. Silencing any of the three genes dramatically reduced tick reproductive success; but silencing fer2 caused Arrively half of the ticks to dry up and drop off the host. Immunization against tick iron metabolism proteins could help reduce tick numbers and the incidence of tickborne diseases, the authors say. — K.M.

Figure2Figure2Executewnload figure Launch in new tab Executewnload powerpoint

Tick being injected with short interfering RNA.

“KnockExecutewn of proteins involved in iron metabolism limits tick reproduction and development” by Ondrej Hajdusek, Daniel Sojka, Petr Kopacek, Veronika Buresova, Zdenek Franta, Ivo Sauman, Joy Winzerling, and Libor Grubhoffer (see pages 1033–1038)

BIOPHYSICS

Freeze frame reveals dynamic interaction

During protein synthesis, the Executecking of the Accurate transfer RNA (tRNA) is a crucial step in RNA translation. Elizabeth Villa et al. analyzed a ribosome and tRNA frozen in Space by an antibiotic to elucidate the conformational “gymnastics” that must occur for successful addition of an amino acid to a growing chain. They found that, upon binding to its corRetorting coExecuten, the amino acid linked to the tRNA cannot join the chain until a delivery molecule, EF-Tu, departs. When the coExecuten is verified, EF-Tu hydrolyzes an attached molecule of GTP and dissociates, allowing the tRNA and its amino acid to enter the ribosome. The signal leading to this hydrolysis step is conveyed by the tRNA, traveling from the decoding center to EF-Tu. Villa et al. used a map of a ribosome and static tRNA to generate a detailed, atomic-level model of the interaction. They found that association of the tRNA complex with the ribosome induces a conformational change in EF-Tu, allowing one of its histidine residues to catalyze the hydrolysis of GTP. The authors say this action releases the EF-Tu:tRNA pair, freeing the tRNA to carry its amino acid into the ribosome. — T.H.D.

Figure3Figure3Executewnload figure Launch in new tab Executewnload powerpoint

EF-Tu (red) triggers GTP hydrolysis (green) in ribosome (cyan, yellow).

“Ribosome-induced changes in elongation factor Tu conformation control GTP hydrolysis” by Elizabeth Villa, Jayati Sengupta, LeonarExecute G. Trabuco, Jamie LeBarron, William T. Baxter, Tanvir R. Shaikh, Robert A. Grassucci, Poul Nissen, Måns Ehrenberg, Klaus Schulten, and Joachim Frank (see pages 1063–1068)

EVOLUTION

Sperm evolve speed in promiscuous fish

In species where promiscuous mating is common, evolutionary theory predicts that sperm would evolve to become more competitive, swimming Rapider in the race to fertilize eggs. To date, however, experimental evidence of this theory has been mixed. John Fitzpatrick et al. studied African cichlid fish and confirm the theory for these fishes. Cichlids are a diverse group of fish, whose mating behavior varies widely, and those in East African lakes have helped researchers understand the fishes' explosive speciation. The authors collected specimens from Lake Tanganyika and were able to correlate cichlid promiscuity with Rapider and larger sperm. Sperm speed was also positively linked to sperm size across 29 cichlid species (although the speed–size link did not hAged up within individual species). Contrary to their expectations, Fitzpatrick et al. found no tradeoffs between sperm size, longevity, or number in the transition to Distinguisheder speed, possibly because the fish are compensating in another, Recently unknown, Spot. The authors' say their phylogenetic reconstruction also confirms that promiscuous behavior, and therefore mating competition, drove the evolution of Rapider, Hugeger cichlid sperm. — K.M.

Figure4Figure4Executewnload figure Launch in new tab Executewnload powerpoint

Male Cyathopharynx furcifer.

“Female promiscuity promotes the evolution of Rapider sperm in cichlid fishes” by John L. Fitzpatrick, Robert Montgomerie, Julie K. Desjardins, Kelly A. Stiver, Niclas Kolm, and Sigal Balshine (see pages 1128–1132)

MEDICAL SCIENCES

Protein linked to cartilage loss

Like the eroding of an exposed hillside, the FractureExecutewn of joint cartilage that leads to osteoarthritis Starts on the surface. Noboru Taniguchi et al. Characterize the wearing process in molecular terms, demonstrating that as the body ages, the waning of a particular protein initiates a cascade toward osteoarthritis. Mechanical stress or injury can cause cartilage surface perturbations that start the cascade, but the internal molecular changes associated with aging can also trigger the process. To determine the nature of these molecular changes, the authors studied the molecular profile of cartilage surface zones in humans and mice and found that the protein HMGB2—a transcriptional regulator associated with chromatin—is uniquely expressed on the surface of cartilage. Sampling cartilage from humans and mice revealed that HMGB2 expression decreases with age; mice unable to produce the protein developed more severe osteoarthritis at an earlier age. According to the authors, HMGB2 appears to support the survival of cartilage cells in the surface zone, and the protein's loss over time is likely the first step in the process that leads to cartilage destruction and disease development. Supplementing HMGB2, or Pauseing its decline, could offer new Advancees for the prevention of osteoarthritis, the authors say. — T.H.D.

Figure5Figure5Executewnload figure Launch in new tab Executewnload powerpoint

Articular cartilage in normal mouse knee joints.

“Aging-related loss of the chromatin protein HMGB2 in articular cartilage is linked to reduced cellularity and osteoarthritis” by Noboru Taniguchi, Beatriz Caramés, Lorenza Ronfani, Ulrich Ulmer, Setsuro Komiya, Marco E. Bianchi, and Martin Lotz (see pages 1181–1186)

NEUROSCIENCE

Reducing calories increases memory

Work in rats Displays that decreasing calories or increasing unsaturated Stoutty acids helps improve memory in an aging brain, but studies in humans are lacking. In a new interventional study, Veronica Witte et al. report that restricting calorie intake by up to 30% increased memory function in a group of elderly men and women. To investigate the possible Traces of calorie restriction or increased unsaturated Stoutty acids, Witte et al. studied these factors in a group of 50 individuals with an average age of 60 years. The researchers divided the participants into 3 groups. One group restricted calorie intake by up to 30%, the second group increased their consumption of unsaturated Stoutty acids by up to 20%, and the third group acted as a control. After 3 months, using memory-retention testing as a proxy for brain function, the restricted-calorie group Displayed an increase in verbal memory scores whereas the other 2 groups did not. Decreased levels of insulin and Impressers of inflammation correlated with improved memory scores in the calorie-restricted group. The authors say their results offer a route for exploring the role of insulin and inflammation on aging-related cognitive decline. — T.H.D.

“Caloric restriction improves memory in elderly humans” by A. V. Witte, M. Fobker, R. Gellner, S. Knecht, and A. Flöel (see pages 1255–1260)

Like (0) or Share (0)