138 research outputs found
Quantifying Condition-Dependent Intracellular Protein Levels Enables High-Precision Fitness Estimates
Countless studies monitor the growth rate of microbial populations as a measure of fitness. However, an enormous gap separates growth-rate differences measurable in the laboratory from those that natural selection can distinguish efficiently. Taking advantage of the recent discovery that transcript and protein levels in budding yeast closely track growth rate, we explore the possibility that growth rate can be more sensitively inferred by monitoring the proteomic response to growth, rather than growth itself. We find a set of proteins whose levels, in aggregate, enable prediction of growth rate to a higher precision than direct measurements. However, we find little overlap between these proteins and those that closely track growth rate in other studies. These results suggest that, in yeast, the pathways that set the pace of cell division can differ depending on the growth-altering stimulus. Still, with proper validation, protein measurements can provide high-precision growth estimates that allow extension of phenotypic growth-based assays closer to the limits of evolutionary selection
Short--range impurity in the vicinity of a saddle point and the levitation of the 2D delocalized states in a magnetic field
The effect of a short--range impurity on the transmission through a
saddle--point potential for an electron, moving in a strong magnetic field, is
studied. It is demonstrated that for a random position of an impurity and
random sign of its potential the impurity--induced mixing of the Landau levels
diminishes {\em on average} the transmission coefficient. This results in an
upward shift (levitation) of the energy position of the delocalized state in a
smooth potential. The magnitude of the shift is estimated. It increases with
decreasing magnetic field as .Comment: LaTeX, 20 page
Debris Disks: Probing Planet Formation
Debris disks are the dust disks found around ~20% of nearby main sequence
stars in far-IR surveys. They can be considered as descendants of
protoplanetary disks or components of planetary systems, providing valuable
information on circumstellar disk evolution and the outcome of planet
formation. The debris disk population can be explained by the steady
collisional erosion of planetesimal belts; population models constrain where
(10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size)
typically form in protoplanetary disks. Gas is now seen long into the debris
disk phase. Some of this is secondary implying planetesimals have a Solar
System comet-like composition, but some systems may retain primordial gas.
Ongoing planet formation processes are invoked for some debris disks, such as
the continued growth of dwarf planets in an unstirred disk, or the growth of
terrestrial planets through giant impacts. Planets imprint structure on debris
disks in many ways; images of gaps, clumps, warps, eccentricities and other
disk asymmetries, are readily explained by planets at >>5au. Hot dust in the
region planets are commonly found (<5au) is seen for a growing number of stars.
This dust usually originates in an outer belt (e.g., from exocomets), although
an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of
Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018
Monoclonal Antibody and Fusion Protein Biosimilars Across Therapeutic Areas: A Systematic Review of Published Evidence
A Nutrient-Driven tRNA Modification Alters Translational Fidelity and Genome-wide Protein Coding across an Animal Genus
<div><p>Natural selection favors efficient expression of encoded proteins, but the causes, mechanisms, and fitness consequences of evolved coding changes remain an area of aggressive inquiry. We report a large-scale reversal in the relative translational accuracy of codons across 12 fly species in the <i>Drosophila</i>/<i>Sophophora</i> genus. Because the reversal involves pairs of codons that are read by the same genomically encoded tRNAs, we hypothesize, and show by direct measurement, that a tRNA anticodon modification from guanosine to queuosine has coevolved with these genomic changes. Queuosine modification is present in most organisms but its function remains unclear. Modification levels vary across developmental stages in <i>D. melanogaster</i>, and, consistent with a causal effect, genes maximally expressed at each stage display selection for codons that are most accurate given stage-specific queuosine modification levels. In a kinetic model, the known increased affinity of queuosine-modified tRNA for ribosomes increases the accuracy of cognate codons while reducing the accuracy of near-cognate codons. Levels of queuosine modification in <i>D. melanogaster</i> reflect bioavailability of the precursor queuine, which eukaryotes scavenge from the tRNAs of bacteria and absorb in the gut. These results reveal a strikingly direct mechanism by which recoding of entire genomes results from changes in utilization of a nutrient.</p></div
The evolution of heat shock protein sequences, cis-regulatory elements, and expression profiles in the eusocial Hymenoptera
Measurement of surface recombination of excess carriers by use of the double modulation technique
The well characterized (100)-Si surface subjected to low energy ion irradiation is used to demonstrate the capability of the contactless measurement of the surface recombination velocity of excess carriers by applying the photothermal response technique under high vacuum conditions. During and after the processing the photothermal response is recorded in the frequency domain. From the wide range frequency sweep surface recombination velocities between 1 m/s up to 1000 m/s can be extracted
�ber die wirkung der sonneneinstrahlung auf aktivit�t und position der larven von Euroleon nostras fourcr. (-Myrmeleon europaeus McLachl.) in den trichterbodenfallen
Vermitteln die etablierten Notfallkurse Ärzten im Sanitätsdienst der Bundeswehr genügend Sicherheit für notärztliches Handeln im Auslandseinsatz? Eine Pilotstudie im Rahmen eines neuartigen Ausbildungskonzepts am Bundeswehrkrankenhaus Ulm
Vermeiden des Abproduktzwangsanfalls bei der Herstellung von Polyaluminiumchloriden als hochwirksame Flockungsmittel der Wasseraufbereitung Abschlussbericht
Aluminum hydroxide chlorides, which are known as polyaluminum (PAC), are characterized by the following main advantages over neutral salts: higher flocculating efficiency while dosages are lower and sludges are reduced, reduced carry-over of salts into water, higher efficiency at low water temperatures, i.e. advantages in the case of system operation in winter, less pronounced drop in the pH value. The research project under review was dedicated to the development of a method for industrial production of high-flocculation waste-avoiding polyaluminum chlorides which are equivalent or superior to the products presently available on the market. (orig.)SIGLEAvailable from TIB Hannover: F94B1228+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman
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