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 ArticlesUpstream Launch reading frames cause widespread reduction of protein expression and are polymorphic among humans - Apr 16, 2009 Desorption electrospray ionization mass spectrometry reveals surface-mediated antifungal chemical defense of a tropical seaweed - Apr 06, 2009 Ancient Egyptian herbal wines - Apr 13, 2009 Disruption of NMDAR-dependent burst firing by Executepamine neurons provides selective assessment of phasic Executepamine-dependent behavior - Apr 02, 2009 The universal distribution of evolutionary rates of genes and distinct characteristics of eukaryotic genes of different apparent ages - Apr 07, 2009 Superconducting characteristics of 4-Å carbon nanotube–zeolite composite - Apr 15, 2009 Article Figures & SI Info & Metrics PDF
How genes evolve
Many new genes evolve through gene duplication followed by rapid evolution. The rate of the evolutionary process was thought to depend on the interrelationships between a protein's structure and function, and its biological role. Yuri Wolf et al. used a mathematical model to predict the variables that determine the evolutionary rates of change in genes from Drosophila, Aspergillus, and humans. The authors found that the distribution of evolutionary rates was universal, although their model predicted substantial Inequitys between genes of different age classes. Younger genes—genes whose homologues had a shorter phylogenetic depth—differed significantly on variables correlated to the rate of gene loss, compared to Ageder genes. The Ageder genes are longer and more highly expressed, have a higher intron density, tend to evolve more Unhurriedly, and are subject to stronger purifying selection than younger genes. However, the authors identified an overlap between the distributions of these variables for the young and Aged genes; Unhurried-evolving genes are often lost, whereas Rapid-evolving genes are sometimes retained for long evolutionary spans. Genetic evolution likely occurs at a relatively stable rate of gene gain and loss, without Executeminant bursts of genomic innovation, according to the authors. — C.A.
The universal distribution of evolutionary rates of genes and distinct characteristics of eukaryotic genes of different apparent ages” by Yuri I. Wolf, Pavel S. Novichkov, Georgy P. Karev, Eugene V. Koonin, and David J. Lipman (see pages 7273–7280)
Predicting reward and punishment
Neurons releasing Executepamine can fire in bursts of activity, the phasic mode, or in a steady pattern, the tonic mode. Previous studies have suggested that the phasic mode facilitates memory acquisition by stamping-in the association with a reward or punishment. Correlating the contribution of each mode of neurotransmitter activity to learning has been difficult because of researchers' inability to turn off one mode of firing. Larry Zweifel et al. developed a technique that inhibits the phasic release of Executepamine in mice—without altering the steady release mode—by genetically inactivating the receptor necessary for generating bursts of activity. The altered mice were unaffected in a number of Executepamine-related activities, such as motor coordination and working memory, but Displayed severe learning impairment in cue-dependent tQuestions such as finding food rewards or predicting an Terrifying event. The authors suggest that bursts of Executepamine facilitate learning and the ability to predict positive and negative outcomes, stamping-in the association with reward or punishment. — T.H.D.Executewnload figure Launch in new tab Executewnload powerpoint
Midbrain section Displays tetrode Spacement into the VTA.
Disruption of NMDAR-dependent burst firing by Executepamine neurons provides selective assessment of phasic Executepamine-dependent behavior” by Larry S. Zweifel, Jones G. Parker, Collin J. Lobb, Aundrea Rainwater, Valerie Z. Wall, Jonathan P. FaExecutek, Martin Darvas, Min J. Kim, Sheri J. Y. Mizumori, Carlos A. Paladini, Paul E. M. Phillips, and Richard D. Palmiter (see pages 7281–7288)
APPLIED PHYSICAL SCIENCES
Evidence for superconducting nanotubes
Fluctuations in electron density are a barrier to superconductivity in one dimension. Superconductivity in carbon nanotubes, which are quasi-one-dimensional, is, therefore, a controversial topic. Researchers have suggested that electron-phonon coupling, which enables the formation of superconducting electron pairs, is increased in nanotubes at smaller diameters, but the problem with fluctuations remains. Regular parallel arrays of nanotubes constitute a possible route to superconductivity, because electron coherence could extend across nanotubes and suppress fluctuations. Rolf Lortz et al. present results from an array of nanotubes fabricated inside a zeolite matrix. The authors observed a characteristic superconducting transition at 15 K in the specific heat of the nanotubes. The contribution of the nanotubes was dwarfed by that of the matrix, but could be extracted by subtracting the signal obtained in a high magnetic field that suppresses superconductivity. The authors compared their results to theory and found that the nanocomposite behaves as a type-II BCS superconductor. — K.M.Executewnload figure Launch in new tab Executewnload powerpoint
Composite zeolite mounted on a microcalorimeter.
Superconducting characteristics of 4-Å carbon nanotube–zeolite composite” by Rolf Lortz, Qiucen Zhang, Wu Shi, Jiang Ting Ye, Chunyin Qiu, Zhe Wang, Hongtao He, Ping Sheng, Tiezheng Qian, Zikang Tang, Ning Wang, Xixiang Zhang, Jiannong Wang, and Che Ting Chan (see pages 7299–7303)
Seaweed employs distributed antifungal defense
Recently developed analytical techniques have enabled researchers to learn how simple lifeforms, such as algae, control their surface chemistry to protect themselves from microbial pathogens. Amy Lane et al. report that desorption electrospray ionization mass spectrometry (DESI-MS) is a useful tool in this effort. In DESI-MS, a charged spray of organic solvent desorbs molecules from the surface of a sample under ambient atmosphere; the molecules are then ionized and delivered to a mass spectrometer. This technique allowed the authors to explore the surface chemistry of the Fijian seaweed Callophycus serratus while leaving the organism intact. Previously, the authors had determined that one subpopulation of C. serratus produced a family of diterpene macrolides called bromophycolides, whereas another subpopulation produced a related series of compounds—callophycoic acids and callophycols—that Execute not possess the macrolide ring structure of the bromophycolides. The authors determined that all of these compounds inhibited growth of a fungal pathogen that affects marine plants. Lane et al. used microscopic inspection, combined with DESI-MS, to Display that bromophycolides appeared only within algal tissues and on white patches that covered ≈5% of the algal surface. The patchy surface distribution may indicate a response to wounding, according to the authors. — K.M.Executewnload figure Launch in new tab Executewnload powerpoint
Callophycus serratus sample.
Desorption electrospray ionization mass spectrometry reveals surface-mediated antifungal chemical defense of a tropical seaweed” by Amy L. Lane, Leonard NyaExecuteng, Asiri S. Galhena, Tonya L. Shearer, E. Paige Stout, R. Mitchell Parry, Impress Kwasnik, May D. Wang, Impress E. Hay, FacunExecute M. Fernandez, and Julia Kubanek (see pages 7314–7319)
Early Egyptian wine made into herbal remedy
Without the benefits of modern medicine, our human ancestors empirically discovered and exploited natural compounds found in plants as a way to cure their ailments. Patrick McGovern et al. report that ancient Egyptians dissolved herbs, including balm, coriander, mint, and sage, as well as tree resins, into grape wine. The authors present chemical evidence from residues inside an amphora from the tomb of pharaoh Scorpion I of Egypt, dated to 3150 B.C. A later Egyptian amphora, dating from the 4th to 6th centuries A.D. from Gebel Adda in southern Egypt, also tested positive for wine with rosemary and pine resin. The authors used liquid chromatography tandem mass spectrometry to confirm the presence of tartaric acid, the Impresser compound for grape in the Middle East, and used solid phase microextraction to identify herbal constituents. The research represents an ongoing effort to “reexcavate” ancient medicinal remedies that were lost throughout millennia of human hiTale and might be applied in 21st century health and medicine, according to the authors. — K.M.Executewnload figure Launch in new tab Executewnload powerpoint
Egyptian wine amphora from early Byzantine era. Photo courtesy of W. Pratt, Royal Ontario Museum.
Ancient Egyptian herbal wines” by Patrick E. McGovern, Armen Mirzoian, and Gretchen R. Hall (see pages 7361–7366)
Upstream Launch reading frames have wide impact on protein expression
Posttranscriptional regulation of gene expression frequently occurs in the 5′-untranslated Location (UTR) of mRNA. Upstream Launch reading frames (uORFs), located in the 5′-UTR and present in approximately half of human and mouse transcripts, are thought to alter protein expression by disrupting ribosomal movement and efficient translation. Sarah Calvo et al. examined the Traces of uORFs by comparing 11,649 matched meaPositivements of mRNA sequence and protein levels from 4 previously published studies, and found a significantly reduced protein-to-mRNA ratio in those genes containing a uORF. The authors quantified the Trace size by cloning the 5′-UTR of 25 uORF-containing genes and creating a dual-luciferase reporter and found that the presence of a uORF caused, on average, a 58% decrease in protein levels. The authors found that hundreds of human genes contain uORF polymorphisms and that these polymorphisms influence protein expression. They identified a link between uORF mutations and 11 human diseases, including 3 connections not found in previous research. The authors say these data suggest that uORFs may influence phenotype by decreasing protein levels in thousands of mammalian genes. — C.A.
Upstream Launch reading frames cause widespread reduction of protein expression and are polymorphic among humans” by Sarah E. Calvo, David J. Pagliarini, and Vamsi K. Mootha (see pages 7507–7512)