Chromatin Preparation and Chromatin Immuno-precipitation from Drosophila Embryos

This protocol provides specific details on how to perform Chromatin immunoprecipitation (ChIP) from Drosophila embryos. ChIP allows the matching of proteins or histone modifications to specific genomic regions. Formaldehyde-cross-linked chromatin is isolated and antibodies against the target of interest are used to determine whether the target is associated with a specific DNA sequence. This can be performed in spatial and temporal manner and it can provide information about the genome-wide localization of a given protein or histone modification if coupled with deep sequencing technology (ChIP-Seq)

The DPOSS II distant compact group survey: the EMMI-NTT spectroscopic sample

This paper presents the results of the redshift survey of 138 candidate compact groups from the DPOSS II catalog (Iovino et al., 2003; de Carvalho et al. 2005), which extends the available redshift range of spectroscopically confirmed compact groups of galaxies to z~0.2. The aims of the survey are to confirm group membership via spectroscopic redshift information, to measure the characteristic parameters of the confirmed groups, namely mass, radius, luminosity, velocity dispersion and crossing time, and to compare them with those of nearby compact groups. Using available information from the literature, we also studied the surrounding group environment and searched for additional, previously unknown, group members, or larger scale structures to whom the group might be associated. Of the 138 observed groups, 96 had three or more concordant galaxies, i.e. a 70% success rate. Of these 96, 62 are isolated on the sky, while the other 34 are close on the sky to a larger scale structure. The remaining objects turned out to be couple of pairs or chance projection of galaxies on the sky. Group environment and the characteristics parameters (mass, crossing time, velocity dispersion) are evaluated and discussed.Comment: Accepted on A&A, version updated to match the printed one. The paper will read well even without printing figures 8 and

Redshift-Space Distortions and the Real-Space Clustering of Different Galaxy Types

We study the distortions induced by peculiar velocities on the redshift-space correlation function of galaxies of different morphological types in the Pisces-Perseus redshift survey. Redshift-space distortions affect early- and late-type galaxies in different ways. In particular, at small separations, the dominant effect comes from virialized cluster cores, where ellipticals are the dominant population. The net result is that a meaningful comparison of the clustering strength of different morphological types can be performed only in real space, i.e., after projecting out the redshift distortions on the two-point correlation function xi(r_p,pi). A power-law fit to the projected function w_p(r_p) on scales smaller than 10/h Mpc gives r_o = 8.35_{-0.76}^{+0.75} /h Mpc, \gamma = 2.05_{-0.08}^{+0.10} for the early-type population, and r_o = 5.55_{-0.45}^{+0.40} /h Mpc, \gamma = 1.73_{-0.08}^{+0.07} for spirals and irregulars. These values are derived for a sample luminosity brighter than M_{Zw} = -19.5. We detect a 25% increase of r_o with luminosity for all types combined, from M_{Zw} = -19 to -20. In the framework of a simple stable-clustering model for the mean streaming of pairs, we estimate sigma_12(1), the one-dimensional pairwise velocity dispersion between 0 and 1 /h Mpc, to be 865^{+250}_{-165} km/s for early-type galaxies and 345^{+95}_{-65} km/s for late types. This latter value should be a fair estimate of the pairwise dispersion for ``field'' galaxies; it is stable with respect to the presence or absence of clusters in the sample, and is consistent with the values found for non-cluster galaxies and IRAS galaxies at similar separations.Comment: 17 LaTeX pages including 3 tables, plus 11 PS figures. Uses AASTeX macro package (aaspp4.sty) and epsf.sty. To appear on ApJ, 489, Nov 199

Do Quasars Lens Quasars?

If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be \sim10^{12}M_{\sun} and the sum of all such quasar lenses would have to contain $\sim0.005$ times the closure density of the Universe. It then seems plausible that a very high fraction of all \sim10^{12} M_{\sun} gravitational lenses with redshifts $z\sim1$ contain quasars. Here I propose that these systems have evolved to form the present population of massive galaxies with M$_{\rm B}\leq-22$ and M >5\times10^{11} M_{\sun}.Comment: 6 pages, aas style, ams symbols, ApJL (accepted

Southern Sky Redshift Survey: Clustering of Local Galaxies

We use the two-point correlation function to calculate the clustering properties of the recently completed SSRS2 survey. The redshift space correlation function for the magnitude-limited SSRS2 is given by xi(s)=(s/5.85 h-1 Mpc)^{-1.60} for separations between 2 < s < 11 h-1 Mpc, while our best estimate for the real space correlation function is xi(r) = (r/5.36 h-1 Mpc)^{-1.86}. Both are comparable to previous measurements using surveys of optical galaxies over much larger and independent volumes. By comparing the correlation function calculated in redshift and real space we find that the redshift distortion on intermediate scales is small. This result implies that the observed redshift-space distribution of galaxies is close to that in real space, and that beta = Omega^{0.6}/b < 1, where Omega is the cosmological density parameter and b is the linear biasing factor for optical galaxies. We also use the SSRS2 to study the dependence of xi on the internal properties of galaxies. We confirm earlier results that luminous galaxies (L>L*) are more clustered than sub-L* galaxies and that the luminosity segregation is scale-independent. We find that early types are more clustered than late types, but that in the absence of rich clusters, the relative bias between early and late types in real space, is not as strong as previously estimated. Furthermore, both morphologies present a luminosity-dependent bias, with the early types showing a slightly stronger dependence on luminosity. We also find that red galaxies are significantly more clustered than blue ones, with a mean relative bias stronger than that seen for morphology. Finally, we find that the relative bias between optical and iras galaxies in real space is b_o/b_I $\sim$ 1.4.Comment: 43 pages, uses AASTeX 4.0 macros. Includes 8 tables and 16 Postscript figures, updated reference

Foreign Body Reaction to Hyaluronic Acid (Restylane®): An Adverse Outcome of Lip Augmentation

Non-animal source hyaluronic acid (Restylane®) is a relatively new redefining dermal filler that is being employed with increasing frequency in the fields of dermatology and cosmetic/facial plastic surgery. We report a case of a 74-year-old woman who presented with a firm submucosal nodule of the lower lip, which clinically was thought to represent a benign neoplasm. An excisional biopsy revealed the presence of multiple cyst-like vacuolated areas surrounded by granulomatous tissue composed predominantly of histiocytes and foamy macrophages, consistent with a foreign body reaction. Subsequent to the pathology findings, the patient acknowledged that she had received injections of Restylane® to the lips approximately 6 months before discovering the nodule. She had not mentioned this to her dentist or oral and maxillofacial surgeon to whom she had been referred because she believed that these two events were not related. Although hyaluronic acid-based dermal fillers reportedly have a low incidence of long term side effects, clinicians should be aware of the possible development of foreign body reactions to these injectable agents