A microarray analysis of sex- and gonad-biased gene expression in the zebrafish: Evidence for masculinization of the transcriptome

<p>Abstract</p> <p>Background</p> <p>In many taxa, males and females are very distinct phenotypically, and these differences often reflect divergent selective pressures acting on the sexes. Phenotypic sexual dimorphism almost certainly reflects differing patterns of gene expression between the sexes, and microarray studies have documented widespread sexually dimorphic gene expression. Although the evolutionary significance of sexual dimorphism in gene expression remains unresolved, these studies have led to the formulation of a hypothesis that male-driven evolution has resulted in the masculinization of animal transcriptomes. Here we use a microarray assessment of sex- and gonad-biased gene expression to test this hypothesis in zebrafish.</p> <p>Results</p> <p>By using zebrafish Affymetrix microarrays to compare gene expression patterns in male and female somatic and gonadal tissues, we identified a large number of genes (5899) demonstrating differences in transcript abundance between male and female <it>Danio rerio</it>. Under conservative statistical significance criteria, all sex-biases in gene expression were due to differences between testes and ovaries. Male-enriched genes were more abundant than female-enriched genes, and expression bias for male-enriched genes was greater in magnitude than that for female-enriched genes. We also identified a large number of genes demonstrating elevated transcript abundance in testes and ovaries relative to male body and female body, respectively.</p> <p>Conclusion</p> <p>Overall our results support the hypothesis that male-biased evolutionary pressures have resulted in male-biased patterns of gene expression. Interestingly, our results seem to be at odds with a handful of other microarray-based studies of sex-specific gene expression patterns in zebrafish. However, ours was the only study designed to address this specific hypothesis, and major methodological differences among studies could explain the discrepancies. Regardless, all of these studies agree that transcriptomic sex differences in <it>D. rerio </it>are widespread despite the apparent absence of heterogamety. These differences likely make important contributions to phenotypic sexual dimorphism in adult zebrafish; thus, from an evolutionary standpoint, the precise roles of sex-specific selection and sexual conflict in the evolution of sexually dimorphic gene expression are very important. The results of our study and others like it set the stage for further work aimed at directly addressing this exciting issue in comparative genomics.</p

On the metallicity dependence of crystalline silicates in oxygen-rich asymptotic giant branch stars and red supergiants

We investigate the occurrence of crystalline silicates in oxygen-rich evolved stars across a range of metallicities and mass-loss rates. It has been suggested that the crystalline silicate feature strength increases with increasing mass-loss rate, implying a correlation between lattice structure and wind density. To test this, we analyse Spitzer IRS and Infrared Space Observatory SWS spectra of 217 oxygen-rich asymptotic giant branch stars and 98 red supergiants in the Milky Way, the Large and Small Magellanic Clouds and Galactic globular clusters. These encompass a range of spectral morphologies from the spectrally-rich which exhibit a wealth of crystalline and amorphous silicate features to 'naked' (dust-free) stars. We combine spectroscopic and photometric observations with the GRAMS grid of radiative transfer models to derive (dust) mass-loss rates and temperature. We then measure the strength of the crystalline silicate bands at 23, 28 and 33 microns. We detect crystalline silicates in stars with dust mass-loss rates which span over 3 dex, down to rates of ~10^-9 solar masses/year. Detections of crystalline silicates are more prevalent in higher mass-loss rate objects, though the highest mass-loss rate objects do not show the 23-micron feature, possibly due to the low temperature of the forsterite grains or it may indicate that the 23-micron band is going into absorption due to high column density. Furthermore, we detect a change in the crystalline silicate mineralogy with metallicity, with enstatite seen increasingly at low metallicity.Comment: Accepted for publication in MNRAS, 24 pages, 16 figure

The Influence Of Neutron Capture Rates On The Rare Earth Region Of The r-Process Abundance Pattern

We study the sensitivity of the r-process abundance pattern to neutron capture rates along the rare earth region (A~150 to A~180). We introduce the concepts of large nuclear flow and flow saturation which determine the neutron capture rates that are influential in setting the rare earth abundances. We illustrate the value of the two concepts by considering high entropy conditions favorable for rare earth peak production and identifying important neutron capture rates among the rare earth isotopes. We also show how these rates influence nuclear flow and specific sections of the abundance pattern.Comment: 14 pages, 7 figures, submitted to PR

Shearmeter floats in the area of the WHOI Brazil Basin Tracer Release Experiment : technical and oceanographic data

Six drifting floats designed to measure shear were deployed in the vicinity of the Brazil Basin Tracer Release Experiment. The one-year long time series of oceanographic conditions obtained by the floats are for direct comparison with long-term tracer dispersion. The purpose of the tracer dispersion experiment was to study mixing of Antarctic Bottom Water at approximately 4000 m depth with less dense water above. Two of the floats returned shear records, one from about 1660 m depth and one from about 2800 m depth. Mean shear at 1660 m was 2.2 x 10 -3 s-1 with N = 1.1 cph, about 1.9 times the Garrett-Munk model amount. Mean shear at 2800 m was 1.1 x 10-3 with N = 0.5 cph, about 2.2 times Garrett-Munk. There was no apparent depth structure to the shear recorded by the near-bottom float moving over the mountainous seafloor. The two shear time series and the local tidal velocities were not strongly correlated, but the tide and shear series did have some similarities. Some variability in the 1660-m shear may be due to atmospheric forcing. Three floats deeper than 2800 m returned one-year long trajectories. Two trajectories were persistently eastward.Funding was provided by the National Science Foundation under Grant Nos. OCE-9416014 and OCE-9906685

The Ever Changing Circumstellar Nebula Around UW Centauri

We present new images of the reflection nebula surrounding the R Coronae Borealis Star, UW Cen. This nebula, first detected in 1990, has changed its appearance significantly. At the estimated distance of UW Cen, this nebula is approximately 0.6 ly in radius so the nebula cannot have physically altered in only 8 years. Instead, the morphology of the nebula appears to change as different parts are illuminated by light from the central star modulated by shifting thick dust clouds near its surface. These dust clouds form and dissipate at irregular intervals causing the well-known declines in the R Coronae Borealis (RCB) stars. In this way, the central star acts like a lighthouse shining through holes in the dust clouds and lighting up different portions of the nebula. The existence of this nebula provides clues to the evolutionary history of RCB stars possibly linking them to the Planetary Nebulae and the final helium shell flash stars.Comment: To be published in ApJ Letters. 5 pages, 3 figures (2 in color

Constrained Cosmological Simulations of Dark Matter Halos

The formation and structure of dark matter (DM) halos is studied by means of constrained realizations of Gaussian fields using N-body simulations. A series of experiments of the formation of a 10^{12} Msun halo is designed to study the dependence of the density profile on its merging history. We confirm that the halo growth consists of violent and quiescent phases, with the density well approximated by the Navarro-Frenk-White (NFW) profile during the latter phases. We find that (1) the NFW scale radius R_s stays constant during the quiescent phase and grows abruptly during the violent one. In contrast, the virial radius grows linearly during the quiescent and abruptly during the violent phases. (2) The central density stays unchanged during the quiescent phase while dropping abruptly during the violent phase. (3) The value of \rs reflects the violent merging history of the halo, and depends on the number of violent events and their fractional magnitudes, independent of the time and order of these events. It does not reflect the formation time of the halo. (4) The fractional change in R_s is a nonlinear function of the fractional absorbed kinetic energy within R_s in a violent event.Comment: 5 pages, 2 postscript figures, ApJ emulator, submitted to ApJ Letter

Customers as decision-makers: strategic environmental assessment in the private sector

Despite its diversification and global spread, strategic environmental assessment (SEA) remains limited mainly to activities characterised by well-defined planning processes, typically within the public sector. This article explores the possible application of SEA within certain private-sector contexts where higher-level strategy-making itself is inherently weaker and development is often piecemeal and reactive. The possible adaptation of SEA to the preparation of a strategic document by a particular industrial concern in the UK is examined: this draws attention to the multi-actor nature of development processes within the industry. This leads to the suggestion that SEA in this setting should be thought of as a form of environmental advocacy oriented towards industrial customers, who are understood as sharing a decision-making role in infrastructure development.</p

On the Excitation and Formation of Circumstellar Fullerenes

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds; Tc1, SMP SMC16, and SMP LMC56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C60 and little or no emission is present from Polycyclic Aromatic Hydrocarbons (PAHs). The strength of the fullerene bands in the three planetary nebulae is very similar, while the ratio of the [NeIII]15.5um/[NeII]12.8um fine structure lines, an indicator of the strength of the radiation field, is markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9um region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled Hydrogenated Amorphous Carbon that present emission in this region.Comment: 13 pages, 2 tables, 7 figures, Accepted for publication in Ap

Adipose‐Derived Stem Cells Induce Angiogenesis via Microvesicle Transport of miRNA‐31

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135340/1/sct3201654440.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135340/2/Supplemental_Information.pd