Calorie restriction (CR) promotes longevity. A prevalent mechanistic hypothesis explaining this effect suggests that protein degradation, including mitochondrial autophagy, is increased with CR, removing damaged proteins and improving cellular fitness. At steady state, increased catabolism must be balanced by increasing mitochondrial biogenesis and protein synthesis, resulting in faster protein replacement rates. To test this hypothesis, we measured replacement kinetics and relative concentrations of hundreds of proteins in vivo in long-term CR and ad libitum-fed mice using metabolic (2)H(2)O-labeling combined with the Stable Isotope Labeling in Mammals protocol and LC-MS/MS analysis of mass isotopomer abundances in tryptic peptides. CR reduced absolute synthesis and breakdown rates of almost all measured hepatic proteins and prolonged the half-lives of most (≈ 80%), particularly mitochondrial proteins (but not ribosomal subunits). Proteins with related functions exhibited coordinated changes in relative concentration and replacement rates. In silico expression pathway interrogation allowed the testing of potential regulators of altered network dynamics (e.g. peroxisome proliferator-activated receptor gamma coactivator 1-alpha). In summary, our combination of dynamic and quantitative proteomics suggests that long-term CR reduces mitochondrial biogenesis and mitophagy. Our findings contradict the theory that CR increases mitochondrial protein turnover and provide compelling evidence that cellular fitness is accompanied by reduced global protein synthetic burden.
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ADVERTISEMENT RETURN TO ISSUEPREVCommentaryNEXTThe Flexible Surface: Molecular Studies Explain the Extraordinary Diversity of Surface Chemical PropertiesGabor A. Somorjai and Günther Rupprechter View Author Information University of California at Berkeley, Department of Chemistry, Berkeley, CA 94720Cite this: J. Chem. Educ. 1998, 75, 2, 161Publication Date (Web):February 1, 1998Publication History Received3 August 2009Published online1 February 1998Published inissue 1 February 1998https://doi.org/10.1021/ed075p161RIGHTS & PERMISSIONSArticle Views1799Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSUBJECTS:Adsorption,Catalysis,Hydrocarbons,Metals,Surface chemistry Get e-Alerts
The complete optical spectrum (3200-10,000 A) of supernova 1985f in NGC 4618 is presented. Strong emission lines of O, Ca, C, Mg, Na, Fe and N are present, while H and He absorption lines are conspicuously absent. The spectrum of SN 1985f does not resemble any previously published spectra of supernovae, and it is postulated that its progenitor was a massive Wolf-Rayet star that expelled its outer atmosphere of H and He prior to supernova explosion. Photographs of SN 1985f are provided which illustrate its location in very bright H II regions near the nucleus of NGC 4618. The supernova, so faint at the time of discovery, is overwhelmed by light from the surrounding galaxy in any moderately deep image. A plate obtained in May 1914 reveals the absence of a starlike object at the expected position, and visual observations made in November 1985 indicate that the supernova has faded substantially since March 1985.
The considerable importance of microporous solids such as zeolites in shape-selective catalysis, ion-exchange processes, and molecular sieving applications has inspired the recent extensive efforts to produce analogous materials that are based on metal sulfide,1 metal-organic,2 and organic3 frameworks. A wide variety of molecular building units such as inorganic clusters, metal-organic complexes, porphyrin, organic macrocyles, and cyclic peptides have been linked by either metal ligation or hydrogen bonding to yield diverse extended assemblies having open frameworks. The voids present within these frameworks are usually in the form of channels or chambers where a guest molecule that was introduced during the synthesis resides. At least three issues pose a challenge to those embarking on the designed synthesis of crystalline microporous materials of this kind. First, the large open space within the constructed framework is often found to be occupied by other frameworks that are copies of the original to give an interpenetrating framework structure leaving either little or no voided space in the crystal. Second, since most of the assembly reactions are performed at or near room temperature, the formation of the ultimate product in crystalline form is usually found to be more an art than a science. This is due to the absence of a temperature gradient that allows for slow nucleation and consequently single crystal formation. Third, attempts to evaluate the porosity in these materials by exchanging or decomposing the guest species have in most cases resulted in destruction of the assembled frameworks leading to nonporous solids. This chapter describes our recent research efforts to address these issues. The molecular building block approach for the achievement of these materials will be outlined.
Abstract The available substructure method and computer program for the steady‐state, harmonic response analysis of arch dams, including the hydrodynamic effects, are extended to consider flexibility of the foundation rock and to include Fourier synthesis of harmonic responses to obtain the earthquake response of arch dams. By efficient evaluation of hydrodynamic terms, interpolation of frequency response functions and more efficient computer programming, the computational costs for analysing arch dams have been reduced by an order of magnitude relative to the available procedure.
view Abstract Citations (348) References (63) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A search for "dwarf" Seyfert 1 nuclei. I. The initial data and results. Filippenko, A. V. ; Sargent, W. L. W. Abstract Preliminary results of a sensitive search for low-luminosity Seyfert 1 nuclei are presented. The sample contained a total of 75 galaxies with spectral resolutions of 2.5 A, and high signal-to-noise ratios of about 100/1 in the range 6200-6880 A. The search was carried out using the Palomar Hale telescope and a double spectrograph. The wavelengh scale was established by fitting a quartic polynomial to unblended emission lines from the Ar and Ne comparison spectra. In comparison with forbidden emission, H-alpha emission exhibited broad wings in 19-28 objects, including 3-5 E or E/50 galaxies. Op the twenty Liner galaxies in the sample, 8-12 showed broad H-alpha lines with smaller equivalent widths than in low-luminosity AGNs. The forbidden line of O I in one third of the Liner galaxies was broader than the S II forbidden line. On the basis of the preliminary results, it is suggested that that the faint end of the luminosity function of AGNs is more populated than has previously been believed. A list of the observations is given. Publication: The Astrophysical Journal Supplement Series Pub Date: March 1985 DOI: 10.1086/191012 Bibcode: 1985ApJS...57..503F Keywords: Astronomical Spectroscopy; Galactic Nuclei; Line Spectra; Seyfert Galaxies; Active Galactic Nuclei; H Alpha Line; Quasars; Spectral Line Width; Astrophysics full text sources ADS | data products SIMBAD (76) NED (75) Related Materials (6) Part 2: 1995ApJS...98..477H Part 3: 1997ApJ...487..568H Part 4: 1997ApJS..112..315H Part 5: 1997ApJS..112..391H Part 6: 2003ApJ...583..159H Part 7: 2009ApJS..183....1H
