The relationship between enzyme architecture and substrate specificity among archaeal pre-tRNA splicing endonucleases has been investigated more deeply, by using biochemical assays and model building. The enzyme from Archeoglobus fulgidus (AF) is particularly interesting: it cleaves the bulge-helix-bulge target without requiring the mature tRNA domain, but, when the target is a bulge-helix-loop...

Context. It has been suggested that the ratio of total-to-selective extinction R V in dust in the interstellar medium differs in the Galactic bulge from its value in the local neighborhood. Aims. We attempt to test this suggestion. Methods. The mid-infrared hydrogen lines in 16 Galactic bulge PNe measured by the Spitzer Space Telescope are used to determine the extinction corrected Hβ flux. Thi...

We have identified five new R Coronae Borealis (RCB) stars in the Galactic bulge using the MACHO Project photometry database, raising the total number of known Galactic RCB stars to about 40. We have obtained spectra to confirm the identifications. The fact that four out of the five newly identified RCB stars are “cool” (Teff < 6000 K) rather than “warm” (Teff > 6000 K) suggests that the prepon...

Adult mammalian epidermis contains multiple stem cell populations in which quiescent and more proliferative stem and progenitor populations coexist. However, the precise interrelation of these populations in homeostasis remains unclear. Here, we blocked the contribution of quiescent keratin 19 (K19)-expressing bulge stem cells to hair follicle formation through genetic ablation of the essential...

We analyze the colour magnitude diagram of the field population in the direction of the bulge cluster NGC 6553 to discuss the stellar field component projected towards the cluster. In particular we investigate the nature of a peculiar feature, called “red flare” which appears as a faint turnoff, located 2 magnitudes about below the turnoff of the cluster, with a sparse trace of a sub-giant bran...

We present abundance results from our Keck/HIRES observations of giants in the Galactic Bulge. We confirm that the metallicity distribution of giants in the low-reddening bulge field Baade’s Window can be well-fit by a closed-box enrichment model. We also confirm previous observations that find enhanced [Mg/Fe], [Si/Fe] and [Ca/Fe] for all bulge giants, including those at super-solar metallicit...

Kn-band imaging of a sample of 30 edge-on spiral galaxies with a boxy or peanut-shaped (B/PS) bulge is discussed. Galaxies with a B/PS bulge tend to have a more complex morphology than galaxies with other bulge types, unsharp-masked images revealing structures that trace the major orbit families of three-dimensional bars. Their surface brightness profiles are also more complex, typically contai...

The interstellar gas flow in the inner disk of M31 is modelled using a new, two dimensional, grid based, hydrodynamics code. The potential of the stellar bulge is derived from its surface brightness profile. The bulge is assumed to be triaxial and rotating in the same plane as the disk in order to explain the twisted nature of M31’s central isophotes and the non circular gas velocities in the i...

A view of the Galactic bulge by means of their globular clusters is fundamental for a deep understanding of its formation and evolution. Connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances, and ages should shed light on different stellar population components. Based on spatial distribution and metallicity, we define a probable b...

The bulge contains the most chemically evolved old stellar population in the Milky Way. Thanks to microlensing, it is now possible to obtain high resolution echelle spectra of bulge stars near the main sequence turn-off, and study the abundance of elements that are affected by stellar evolution, such as lithium. We have observed with the HIRES spectrograph on the Keck I 10m telescope the source...