Limited Lifespan of Fragile Regions in Mammalian Evolution

An important question in genome evolution is whether there exist fragile regions (rearrangement hotspots) where chromosomal rearrangements are happening over and over again. Although nearly all recent studies supported the existence of fragile regions in mammalian genomes, the most comprehensive phylogenomic study of mammals (Ma et al. (2006) Genome Research 16, 1557-1565) raised some doubts about their existence. We demonstrate that fragile regions are subject to a "birth and death" process, implying that fragility has limited evolutionary lifespan. This finding implies that fragile regions migrate to different locations in different mammals, explaining why there exist only a few chromosomal breakpoints shared between different lineages. The birth and death of fragile regions phenomenon reinforces the hypothesis that rearrangements are promoted by matching segmental duplications and suggests putative locations of the currently active fragile regions in the human genome

El uso de parámetros magnéticos en estudios paleolimnológicos en Antártida

En esta contribución se describen las distintas técnicas y mediciones magnéticas utilizadas en Magnetismo Ambiental y Paleomagnetismo. Tales mediciones ofrecen útiles indicadores para realizar estudios relacionados con cambios climáticos y ambientales, así como herramientas de datación. Si bien es ampliamente conocida la utilidad de la susceptibilidad magnética, en primer lugar se discute el potencial y necesidad del uso de parámetros adicionales obtenidos a partir de mediciones de magnetizaciones remanentes (natural, anhistérica e isotérmica), histéresis magnética y estudios termomagnéticos. A continuación se presentan resultados magnéticos obtenidos en sedimentos lacustres del Archipiélago James Ross (NE de la Península Antártica) como un caso de estudio. Se complementa con estudios sedimentológicos, hidroquímicos, geoquímicos y de estadística multivariada, pero se pone énfasis en los parámetros magnéticos y su relación con los distintos procesos que ocurren en los sistemas lacustres antárticos. Se analiza además el uso de las paleointensidades relativas como herramienta de datación en lagunas antárticas

Accelerated Cosmological Models in First-Order Non-Linear Gravity

The evidence of the acceleration of universe at present time has lead to investigate modified theories of gravity and alternative theories of gravity, which are able to explain acceleration from a theoretical viewpoint without the need of introducing dark energy. In this paper we study alternative gravitational theories defined by Lagrangians which depend on general functions of the Ricci scalar invariant in minimal interaction with matter, in view of their possible cosmological applications. Structural equations for the spacetimes described by such theories are solved and the corresponding field equations are investigated in the Palatini formalism, which prevents instability problems. Particular examples of these theories are also shown to provide, under suitable hypotheses, a coherent theoretical explanation of earlier results concerning the present acceleration of the universe and cosmological inflation. We suggest moreover a new possible Lagrangian, depending on the inverse of sinh(R), which gives an explanation to the present acceleration of the universe.Comment: 23 pages, Revtex4 fil

El uso de parámetros magnéticos en estudios paleolimnológicos en Antártida

En esta contribución se describen las distintas técnicas y mediciones magnéticasutilizadas en Magnetismo Ambiental y Paleomagnetismo. Tales mediciones ofrecen útilesindicadores para realizar estudios relacionados con cambios climáticos y ambientales,así como herramientas de datación. Si bien es ampliamente conocida la utilidad de lasusceptibilidad magnética, en primer lugar se discute el potencial y necesidad del uso deparámetros adicionales obtenidos a partir de mediciones de magnetizaciones remanentes(natural, anhistérica e isotérmica), histéresis magnética y estudios termomagnéticos. Acontinuación se presentan resultados magnéticos obtenidos en sedimentos lacustresdel Archipiélago James Ross (NE de la Península Antártica) como un caso de estudio.Se complementa con estudios sedimentológicos, hidroquímicos, geoquímicos y deestadística multivariada, pero se pone énfasis en los parámetros magnéticos y su relacióncon los distintos procesos que ocurren en los sistemas lacustres antárticos. Se analizaademás el uso de las paleointensidades relativas como herramienta de datación enlagunas antárticas

Lysyl oxidase is a strong determinant of tumor cell colonization in bone

Lysyl oxidase (LOX) is a secreted copper-dependent amine oxidase whose primary function is to drive collagen crosslinking and extracellular matrix stiffness. LOX in colorectal cancer synergizes with hypoxia-inducible factor-1 (HIF-1) to promote tumor progression. Here we investigated whether LOX/HIF1 endows colorectal cancer cells with full competence for aggressive colonization in bone. We show that a high LOX expression in primary tumors from patients with colorectal cancer was associated with poor clinical outcome, irrespective of HIF-1. In addition, LOX was expressed by tumor cells in the bone marrow from colorectal cancer patients with bone metastases. In vivo experimental studies show that LOX overexpression in colorectal cancer cells or systemic delivery of the conditioned medium from LOX-overexpressing colorectal cancer cells promoted tumor cell dissemination in the bone marrow and enhanced osteolytic lesion formation, irrespective of HIF-1. Conversely, silencing or pharmacologic inhibition of LOX activity blocked dissemination of colorectal cancer cells in the bone marrow and tumor-driven osteolytic lesion formation. In vitro, tumor-secreted LOX supported the attachment and survival of colorectal cancer cells to and in the bone matrix, and inhibited osteoblast differentiation. LOX overexpression in colorectal cancer cells also induced a robust production of IL6. In turn, both LOX and IL6 were acting in concert to promote RANKL-dependent osteoclast differentiation, thereby creating an imbalance between bone resorption and bone formation. Collectively, our findings show that LOX supports colorectal cancer cell dissemination in the bone marrow and they reveal a novel mechanism through which LOX-driven IL6 production by colorectal cancer cells impairs bone homeostasi

Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A > 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

7th Drug hypersensitivity meeting: part two

No abstract availabl

Astrophysical Interpretation Of Pierre Auger Observatory Measurements Of The Uhecr Energy Spectrum And Mass Composition

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