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DNA Rereplication Is Susceptible to Nucleotide-Level Mutagenesis.
The sources of genome instability, a hallmark of cancer, remain incompletely understood. One potential source is DNA rereplication, which arises when the mechanisms that prevent the reinitiation of replication origins within a single cell cycle are compromised. Using the budding yeast Saccharomyces cerevisiae, we previously showed that DNA rereplication is extremely potent at inducing gross chromosomal alterations and that this arises in part because of the susceptibility of rereplication forks to break. Here, we examine the ability of DNA rereplication to induce nucleotide-level mutations. During normal replication these mutations are restricted by three overlapping error-avoidance mechanisms: the nucleotide selectivity of replicative polymerases, their proofreading activity, and mismatch repair. Using lys2InsEA14 , a frameshift reporter that is poorly proofread, we show that rereplication induces up to a 30à higher rate of frameshift mutations and that this mutagenesis is due to passage of the rereplication fork, not secondary to rereplication fork breakage. Rereplication can also induce comparable rates of frameshift and base-substitution mutations in a more general mutagenesis reporter CAN1, when the proofreading activity of DNA polymerase Δ is inactivated. Finally, we show that the rereplication-induced mutagenesis of both lys2InsEA14 and CAN1 disappears in the absence of mismatch repair. These results suggest that mismatch repair is attenuated during rereplication, although at most sequences DNA polymerase proofreading provides enough error correction to mitigate the mutagenic consequences. Thus, rereplication can facilitate nucleotide-level mutagenesis in addition to inducing gross chromosomal alterations, broadening its potential role in genome instability
Approximate expression for the dynamic structure factor in the Lieb-Liniger model
Recently, Imambekov and Glazman [Phys. Rev. Lett. 100, 206805 (2008)] showed
that the dynamic structure factor (DSF) of the 1D Bose gas demonstrates
power-law behaviour along the limiting dispersion curve of the collective modes
and calculated the corresponding exponents exactly. Combining these recent
results with a previously obtained strong-coupling expansion we present an
interpolation formula for the DSF of the 1D Bose gas. The obtained expression
is further consistent with exact low energy exponents from Luttinger liquid
theory and shows nice agreement with recent numerical results.Comment: 4 pages, 3 figure
From gamma ray line signals of dark matter to the LHC
We explore the relationship between astrophysical gamma-ray signals and LHC
signatures for a class of phenomenologically successful secluded dark matter
models, motivated by recent evidence for a ~130 GeV gamma-ray line. We consider
in detail scenarios in which interactions between the dark sector and the
standard model are mediated by a vev-less scalar field \phi, transforming as an
N-plet (N > 3) under SU(2)_L. Since some of the component fields of \phi carry
large electric charges, loop induced dark matter annihilation to \gamma \gamma
and \gamma Z can be enhanced without the need for non-perturbatively large
couplings, and without overproduction of continuum gamma-rays from other final
states. We discuss prospects for other experimental tests, including dark
matter-nucleon scattering and production of \phi at the LHC, where future
searches for anomalous charged tracks may be sensitive. The first LHC hints
could come from the Higgs sector, where loop corrections involving \phi lead to
significantly modified h to \gamma \gamma and h to \gamma Z branching ratios.Comment: 27 pages, 10 figures. v2: added references, fixed import-order issue
with cleveref and hyperref. v3: updated to journal version. v4: erratum
correction to figs. 7-8 for monojet/monophoton cross-section
The course of research into the economic consequences of German works councils
In a recent survey, Frege (2002) concludes that economic analysis of the works council has reached a `dead endÂŽ. The present treatment offers a different conclusion based on a more encompassing review of the evidence. It will identify three distinct phases in the economic analysis of codetermination at the workplace. While Frege just considered studies from the first two phases, it is the third phase of research that contains some of the most positive evaluations to date of works council impact. Even if such estimates appear much exaggerated and the effect of works councils is likely to be small on average, the new literature redirects our research effort towards the factors that produce swings around this average, including differences in works council types and their workplace environments. -- In einem jĂŒngst veröffentlichten Ăberblicksartikel kommt Frege (2002) zu dem Schluss, die ökonomische Analyse des Betriebsrats sei in eine Sackgasse geraten. Die vorliegende Arbeit zieht ein anderes Fazit, das auf einer umfassenderen Betrachtung der empirischen Evidenz beruht. Dabei werden drei Phasen der ökonomischen Analyse der betrieblichen Mitbestimmung unterschieden. WĂ€hrend Frege nur Studien aus den ersten beiden Phasen berĂŒcksichtigte, ist es gerade die dritte Forschungsphase, die einige der positivsten Bewertungen von BetriebsrĂ€ten enthĂ€lt. Selbst wenn derartige EinschĂ€tzungen stark ĂŒbertrieben erscheinen und der Betriebsratseffekt im Durchschnitt relativ gering sein dĂŒrfte, weist die neuere Literatur darauf hin, dass unsere ForschungsbemĂŒhungen sich stĂ€rker auf Faktoren konzentrieren sollten, die Schwankungen um diesen Durchschnitt hervorrufen (wie z.B. unterschiedliche Typen von BetriebsrĂ€ten und deren Arbeitsplatzumgebung).Works council,codetermination,Germany
Extreme morphologies of mantis shrimp larvae
Larvae of stomatopods (mantis shrimps) are generally categorized into four larval types: antizoea, pseudozoea (both representing early larval stages), alima and erichthus (the latter two representing later larval stages). These categories, however, do not reflect the existing morphological diversity of stomatopod larvae, which is largely unstudied. We describe here four previously unknown larval types with extreme morphologies. All specimens were found in the collections of the Zoological Museum, University of Copenhagen and were collected during the Danish Dana Expedition round the world 1928-30. These new larval types all represent erichthus-type larvae, especially differing in their shield morphologies. The shield morphology ranges from almost spherical to rather disc-like, with sometimes extremely elongated spines, but only a general systematic assignment of the larvae was possible. Further investigations of these larvae are crucial to understand their life habits and ecological impact, especially as stomatopod and other crustacean larvae might have a much more important position in the marine ecosystems than their corresponding adults
The (Parlous) State of German Unions
This paper traces the profound decline in German unionism over the course of the last three decades. Today just one in five workers is a union member, and it is now moot whether this degree of penetration is consistent with a corporatist model built on encompassing unions. The decline in union membership and density is attributable to external forces that have confronted unions in many countries (such as globalization and compositional changes in the workforce) and to some specifically German considerations (such as the transition process in postcommunist Eastern Germany) and sustained intervals of classic insider behavior on the part of German unions. The âcorrectivesâ have included mergers between unions, decentralization, and wages that are more responsive to unemployment. At issue is the success of these innovations. For instance, the trend toward decentralization in collective bargaining hinges in part on the health of that other pillar of the dual system of industrial relations, the works council. But works council coverage has also declined, leading some observers to equate decentralization with deregulation. While this conclusion is likely too radical, German unions are at the cross roads. It is argued here that if they fail to define what they stand for, are unable to increase their presence at the workplace, and continue to lack convincing strategies to deal with contemporary economic and political trends working against them, then their decline may become a rout.
Excitable human dynamics driven by extrinsic events in massive communities
Using empirical data from a social media site (Twitter) and on trading
volumes of financial securities, we analyze the correlated human activity in
massive social organizations. The activity, typically excited by real-world
events and measured by the occurrence rate of international brand names and
trading volumes, is characterized by intermittent fluctuations with bursts of
high activity separated by quiescent periods. These fluctuations are broadly
distributed with an inverse cubic tail and have long-range temporal
correlations with a power spectrum. We describe the activity by a
stochastic point process and derive the distribution of activity levels from
the corresponding stochastic differential equation. The distribution and the
corresponding power spectrum are fully consistent with the empirical
observations.Comment: 9 pages, 3 figure
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