Regulation of the mitochondrial transition pore : impact on mammalian aging

Commentary on: Hafner AV et al. Regulation of the mPTP by SIRT3-mediated deacetylation of CypD at lysine 166 suppresses age-related cardiac hypertrophy. Aging. 2010; 12:914-923

The Beat of the Economic Heart: Joseph Schumpeter and Arthur Spiethoff on Business Cycles

The paper discusses the relationship between Arthur Spiethoff and Joseph A. Schumpeter, the men and their works. Had it not been for Spiethoff Schumpeter would in all probability have forever been lost to scientific work. It was Spiethoff who brought the Austrian back to academia and research after a sequence of serious mishaps in politics and banking. Spiethoff's contribution to an analysis of business cycles is then summarized and important similarities and some differences between it and Schumpeter's are pointed out. The view of Spiethoff and Schumpeter that cycles are endogenous and cannot possibly be eliminated without at the same time eliminating the dynamism of the capitalist economy is then couterposed with views of some of their contemporaries and particularly modern mainstream macroeconomics that this is not so.Schumpeter; Spiethoff; business cycles; innovations; creative destruction

Jet trails and Mach cones: The interaction of microquasars with the ISM

A sub-set of microquasars exhibit high peculiar velocity with respect to the local standard of rest due to the kicks they receive when being born in supernovae. The interaction between the radio plasma released by microquasar jets from such high-velocity binaries with the ISM must lead to the production of trails and bow shocks similar to what is observed in narrow-angle tailed radio galaxies and pulsar wind nebulae. We present a set of numerical simulations of this interaction that illuminate the long term dynamical evolution and the observational properties of these microquasar bow shock nebulae and trails. We find that this interaction always produces a structure that consists of a bow shock, a trailing neck, and an expanding bubble. Using our simulations to model emission, we predict that the shock surrounding the bubble and the neck should be visible in H{\alpha} emission, the interior of the bubble should be visible in synchrotron radio emission, and only the bow shock is likely to be detectable in X-ray emission. We construct an analytic model for the evolution of the neck and bubble shape and compare this model with observations of X-ray binary SAX J1712.6-3739.Comment: 33 pages, 13 figures, 1 table; Accepted to Ap

The Contributions of Two Eminent Japanese Scholars on the Development of Economic Theories: Michio Morishima and Takashi Negishi

There can be no doubt that Michio Morishima and Takashi Negishi are two of the most important historians of economic thought of the recent past. Both authors contributed numerous papers and books to the subject, dealing with the works of major economists from the very inception of systematic economic thought at the time of the classical economists up until modern times. And both authors combined a vivid interest in modern economic theory with an interest in what past masters had to say. The paper assesses and compares the motivations of the two authors to engage in the history of economic theories, their similar, but different approaches to do historical research, and their achievements in this regard. Given the remarkable amount of work each one of them accomplished, the paper has to focus attention on a subset of the themes the two authors dealt with. The emphasis will be on (i) their treatment of the classical theories of value, distribution and capital accumulation, especially those of Adam Smith and David Ricardo, (ii) their discussion of the contributions of Karl Marx and some Marxists, (iii) their interpretation of some early and mature marginalist economists, especially Léon Walras, Eugen von Böhm-Bawerk and Knut Wicksell, and (iv) their views about the achievements of John Maynard Keynes. Given the intrinsic complexity of each of these themes, it goes without saying that the paper is bound to proceed largely in terms of synthetic statements.Negishi, Takashi; Morishima, Michio; general equilibrium; Marxist economics; trade; growth

A differential genome-wide transcriptome analysis : impact of cellular copper on complex biological processes like aging and development

The regulation of cellular copper homeostasis is crucial in biology. Impairments lead to severe dysfunctions and are known to affect aging and development. Previously, a loss-of-function mutation in the gene encoding the copper-sensing and copper-regulated transcription factor GRISEA of the filamentous fungus Podospora anserina was reported to lead to cellular copper depletion and a pleiotropic phenotype with hypopigmentation of the mycelium and the ascospores, affected fertility and increased lifespan by approximately 60% when compared to the wild type. This phenotype is linked to a switch from a copper-dependent standard to an alternative respiration leading to both a reduced generation of reactive oxygen species (ROS) and of adenosine triphosphate (ATP). We performed a genome-wide comparative transcriptome analysis of a wild-type strain and the copper-depleted grisea mutant. We unambiguously assigned 9,700 sequences of the transcriptome in both strains to the more than 10,600 predicted and annotated open reading frames of the P. anserina genome indicating 90% coverage of the transcriptome. 4,752 of the transcripts differed significantly in abundance with 1,156 transcripts differing at least 3-fold. Selected genes were investigated by qRT-PCR analyses. Apart from this general characterization we analyzed the data with special emphasis on molecular pathways related to the grisea mutation taking advantage of the available complete genomic sequence of P. anserina. This analysis verified but also corrected conclusions from earlier data obtained by single gene analysis, identified new candidates of factors as part of the cellular copper homeostasis system including target genes of transcription factor GRISEA, and provides a rich reference source of quantitative data for further in detail investigations. Overall, the present study demonstrates the importance of systems biology approaches also in cases were mutations in single genes are analyzed to explain the underlying mechanisms controlling complex biological processes like aging and development

Human CLPP reverts the longevity phenotype of a fungal ClpP deletion strain

Mitochondrial maintenance crucially depends on the quality control of proteins by various chaperones, proteases and repair enzymes. While most of the involved components have been studied in some detail, little is known on the biological role of the CLPXP protease complex located in the mitochondrial matrix. Here we show that deletion of PaClpP, encoding the CLP protease proteolytic subunit CLPP, leads to an unexpected healthy phenotype and increased lifespan of the fungal ageing model organism Podospora anserina. This phenotype can be reverted by expression of human ClpP in the fungal deletion background, demonstrating functional conservation of human and fungal CLPP. Our results show that the biological role of eukaryotic CLP proteases can be studied in an experimentally accessible model organism

Whitening of the Quark-Gluon Plasma

Parton-parton collisions do not neutralize local color charges in the quark-gluon plasma as they only redistribute the charges among momentum modes. We discuss color diffusion and color conductivity as the processes responsible for the neutralization of the plasma. For this purpose, we first compute the conductivity and diffusion coefficients in the plasma that is significantly colorful. Then, the time evolution of the color density due to the conductivity and diffusion is studied. The conductivity is shown to be much more efficient than the diffusion in neutralizing the plasma at the scale longer than the screening length. Estimates of the characteristic time scales, which are based on close to global equilibrium computations, suggest that first the plasma becomes white and then the momentum degrees of freedom thermalize.Comment: 9 pages, revised, to appear in Phys. Rev.