Adenosine to inosine editing by ADAR2 requires formation of a ternary complex on the GluR-B R/G site

RNA editing by members of the ADAR (adenosine deaminase that acts on RNA) enzyme family involves hydrolytic deamination of adenosine to inosine within the context of a double-stranded pre-mRNA substrate. Editing of the human GluR-B transcript is catalyzed by, the enzyme ADAR2 at the Q/R and R/G sites. We have established a minimal RNA substrate for editing based on the RIG site and have characterized the interaction of ADAR2 with this RNA by gel shift, kinetic, and cross-linking analyses. Gel shift analysis revealed that two complexes are formed on the RNA as protein concentration is increased; the ADAR monomers can be crosslinked to one another in an RNA-dependent fashion. We performed a detailed kinetic study of the editing reaction; the data from this study are consistent with a reaction scheme in which formation of an ADAR2.RNA ternary complex is required for efficient RNA editing and in which formation of this complex is rate determining. These observations suggest that RNA adenosine deaminases function as homodimers on their RNA substrates and may partially explain regulation of RNA editing in these systems

Regulating speech on the internet

This paper considers the way in which traditional legal tools for regulating speech have been applied in the Internet environment. The paper commences by describing the aspects of this environment which are regarded as attracting regulatory interest. It then moves on to consider the way in which the regimes of defamation law, censorship law and intellectual property law impact on the Internet. Through this examination the paper raises the question of the appropriateness of the current approach of regulation by analogy

Receptor Mechanisms Common to Platelets and Platelet Progenitor Cells

Blood platelets are small, anucleate cells which circulate freely in the cardiovascular system. One of their major physiological functions is concerned with haemostasis - the cessation of bleeding. However, platelets are also involved in the pathological counterpart of haemostasis - thrombosis. Platelets are derived from megakaryocytes which are large nucleated cells located in the bone marrow

A serological survey of ruminant livestock in Kazakhstan during post-Soviet transitions in farming and disease control

The results of a serological survey of livestock in Kazakhstan, carried out in 1997–1998, are reported. Serum samples from 958 animals (cattle, sheep and goats) were tested for antibodies to foot and mouth disease (FMD), bluetongue (BT), epizootic haemorrhagic disease (EHD), rinderpest (RP) and peste des petits ruminants (PPR) viruses, and to Brucella spp. We also investigated the vaccination status of livestock and related this to changes in veterinary provision since independence in 1991. For the 2 diseases under official surveillance (FMD and brucellosis) our results were similar to official data, although we found significantly higher brucellosis levels in 2 districts and widespread ignorance about FMD vaccination status. The seroprevalence for BT virus was 23%, and seropositive animals were widespread suggesting endemicity, despite the disease not having being previously reported. We found a few seropositives for EHDV and PPRV, which may suggest that these diseases are also present in Kazakhstan. An hierarchical model showed that seroprevalence to FMD and BT viruses were clustered at the farm/village level, rather than at a larger spatial scale. This was unexpected for FMD, which is subject to vaccination policies which vary at the raion (county) level

Black holes and Galactic density cusps -- I. Radial orbit cusps and bulges

In this paper, we study the distribution functions that arise naturally during self-similar radial infall of collisionless matter. Such matter may be thought of either as stars or as dark matter particles. If a rigorous steady state is assumed, then the system is infinite and is described by a universal distribution function given the self-similar index. The steady logarithmic potential case is exceptional and yields the familiar Gaussian for an infinite system with an inverse-square density profile. We show subsequently that for time-dependent radial self-similar infall, the logarithmic case is accurately described by the Fridmann and Polyachenko distribution function. The system in this case is finite but growing. We are able to embed a central mass in the universal steady distribution only by iteration, except in the case of massless particles. The iteration yields logarithmic corrections to the massless particle case and requires a `renormalization' of the central mass. A central spherical mass may be accurately embedded in the Fridmann and Polyachenko growing distribution however. Some speculation is given concerning the importance of radial collisionless infall in actual galaxy formation.Comment: 10 pp, 3 fig

S-cone signals invisible to the motion system can improve motion extraction via grouping by color

Peer reviewedPublisher PD

The Existence of Sterile Neutrino Halos in Galactic Centers as an Explanation of the Black Hole mass - Velocity Dispersion Relation

If sterile neutrinos exist and form halos in galactic centers, they can give rise to observational consequences. In particular, the sterile neutrinos decay radiatively and heat up the gas in the protogalaxy to achieve hydrostatic equilibrium, and they provide the mass to form supermassive blackholes. A natural correlation between the blackhole mass and velocity dispersion thus arises $\log(M_{BH,f}/M_{\odot})=\alpha \log (\sigma /200 {\rm km s^{-1}})+ \beta$ with $\alpha \approx 4$ and $\beta \approx 8$.Comment: Accepted in Ap

On the locus formed by the maximum heights of projectile motion with air resistance

We present an analysis on the geometrical place formed by the set of maxima of the trajectories of a projectile launched in a media with linear drag. Such a place, the locus of apexes, is written in term of the Lambert $W$ function in polar coordinates, confirming the special role played by this function in the problem. In order to characterize the locus, a study of its curvature is presented in two parameterizations, in terms of the launch angle and in the polar one. The angles of maximum curvature are compared with other important angles in the projectile problem. As an addendum, we find that the synchronous curve in this problem is a circle as in the drag-free case.Comment: 7 pages, 6 color eps figures. Synchronous curve added. Typos and style corrected

Characterisation of the genetic diversity of Brucella by multilocus sequencing

<p>Abstract</p> <p>Background</p> <p><it>Brucella </it>species include economically important zoonotic pathogens that can infect a wide range of animals. There are currently six classically recognised species of <it>Brucella </it>although, as yet unnamed, isolates from various marine mammal species have been reported. In order to investigate genetic relationships within the group and identify potential diagnostic markers we have sequenced multiple genetic loci from a large sample of <it>Brucella </it>isolates representing the known diversity of the genus.</p> <p>Results</p> <p>Nine discrete genomic loci corresponding to 4,396 bp of sequence were examined from 160 <it>Brucella </it>isolates. By assigning each distinct allele at a locus an arbitrary numerical designation the population was found to represent 27 distinct sequence types (STs). Diversity at each locus ranged from 1.03–2.45% while overall genetic diversity equated to 1.5%. Most loci examined represent housekeeping gene loci and, in all but one case, the ratio of non-synonymous to synonymous change was substantially <1. Analysis of linkage equilibrium between loci indicated a strongly clonal overall population structure. Concatenated sequence data were used to construct an unrooted neighbour-joining tree representing the relationships between STs. This shows that four previously characterized classical <it>Brucella </it>species, <it>B. abortus</it>, <it>B. melitensis</it>, <it>B. ovis </it>and <it>B. neotomae </it>correspond to well-separated clusters. With the exception of biovar 5, <it>B. suis </it>isolates cluster together, although they form a more diverse group than other classical species with a number of distinct STs corresponding to the remaining four biovars. <it>B. canis </it>isolates are located on the same branch very closely related to, but distinguishable from, <it>B. suis </it>biovar 3 and 4 isolates. Marine mammal isolates represent a distinct, though rather weakly supported, cluster within which individual STs display one of three clear host preferences.</p> <p>Conclusion</p> <p>The sequence database provides a powerful dataset for addressing ongoing controversies in <it>Brucella </it>taxonomy and a tool for unambiguously placing atypical, phenotypically discordant or newly emerging <it>Brucella </it>isolates. Furthermore, by using the phylogenetic backbone described here, robust and rationally selected markers for use in diagnostic assay development can be identified.</p