Writing a wrong: Coupled RNA polymerase II transcription and RNA quality control

Processing and maturation of precursor RNA species is coupled to RNA polymerase II transcription. Co-transcriptional RNA processing helps to ensure efficient and proper capping, splicing, and 3' end processing of different RNA species to help ensure quality control of the transcriptome. Many improperly processed transcripts are not exported from the nucleus, are restricted to the site of transcription, and are in some cases degraded, which helps to limit any possibility of aberrant RNA causing harm to cellular health. These critical quality control pathways are regulated by the highly dynamic protein-protein interaction network at the site of transcription. Recent work has further revealed the extent to which the processes of transcription and RNA processing and quality control are integrated, and how critically their coupling relies upon the dynamic protein interactions that take place co-transcriptionally. This review focuses specifically on the intricate balance between 3' end processing and RNA decay during transcription termination. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Processing > 3' End Processing RNA Processing > Splicing Mechanisms RNA Processing > Capping and 5' End Modifications

Nitrogen fertiliser may pay on tropical grass pastures

Low productivity in sown grass pastures due to a lack of available soil nitrogen can reduce beef production by up to 50% across Queensland. The feasibility of strategic nitrogen (N) fertiliser applications to address these losses was assessed by desktop analyses using data from published studies, local fertiliser trials and expert opinion. These analyses suggest that applying nitrogen to rundown sown grass pastures can produce dramatic increases in dry matter yield and animal production. However, high and consistent response rates in pasture productivity, stocking rates and growth rate of cattle were required for the application of nitrogen fertiliser to be profitable. For the suggested 100 kg N/ha fertiliser rate: average gross margins in the year of application were calculated to increase by 121-217% when dry matter yield responses of 40 kg DM/kg N (i.e. an additional 4000 kg/ha) and an additional liveweight gain of 0.2 kg per adult equivalent (AE)/day can be achieved (i.e. an extra 70 kg AE/year). These economics were very sensitive to the assumed response rates in pasture growth, stocking rate and liveweight gain and did not account for uncertainty in climate and beef prices. New research is proposed to re-assess the responses used in this analysis that are largely based on research 25-40 years ago when soils were generally more fertile and pastures less rundown

Measurement of the ΔS=-ΔQ Amplitude from K_(e3)^0 Decay

We have measured the time distribution of the π^+e^-ν and π^-e^+ν modes from initial K^0's in a spark-chamber experiment performed at the Bevatron. From 1079 events between 0.2 and 7 K_S^0 lifetime, we find ReX=-0.069±0.036, ImX=+0.108_(-0.074)^(+0.092). This result is consistent with X=0 (relative probability = 0.25), but more than 4 standard deviations from the existing world average, +0.14 -0.13i

Geological Surprises at Itezhitezhi Dam, Zambia

An outburst of warm springs together with the development of an extensive area of high pore-water pressures occurred during the first filling of the 50m high earth and rock fill Itezhitezhi Dam on the Kafue River in Zambia. These and other unanticipated events led to extensive geological and hydrogeological investigations that resulted in the implementation of unusual remedial measures. The remedial work was completed before the reservoir reached its full supply level. The dam has since performed successfully. The problems are reviewed in terms of the significance of the site geology. The hydrogeologic problems were found to be caused by the presence of a modified karstic terrane developed on a mineralized, faulted and deeply weathered bedrock of granite and associated rocks. Small differences between the river levels and the piezometric levels in deep porings contributed to a delay in problem identification. The problems encountered and their causes are thought to be without precedent

Disentangling the circumnuclear environs of Centaurus A: Gaseous Spiral Arms in a Giant Elliptical Galaxy

We report the existence of spiral arms in the recently formed gaseous and dusty disk of the closest giant elliptical, NGC 5128 (Centaurus A), using high resolution 12CO(2-1) observations of the central 3 arcmin (3 kpc) obtained with the Submillimeter Array (SMA). This provides evidence that spiral-like features can develop within ellipticals if enough cold gas exists. We elucidate the distribution and kinematics of the molecular gas in this region with a resolution of 4.4 x 1.9 (80 pc x 40 pc). The spiral arms extend from the circumnuclear gas at a radius of 200 pc to at least 1 kiloparsec. The general properties of the arms are similar to those in spiral galaxies: they are trailing, the width is \sim 500 \pm 200 pc, and the pitch angle is 20 degrees. From independent estimates of the time when the HI-rich galaxy merger occurred, we infer that the formation of spiral arms happened on a time scale of less than \sim10^8 yr. The formation of spiral arms increases the gas density and thus the star formation efficiency in the early stages of the formation of a disk.Comment: 13 pages, 4 Figures. Accepted for publication in ApJ

Disentangling the Circumnuclear Environs of Centaurus A: III. An Inner Molecular Ring, Nuclear Shocks and the CO to warm H2 interface

We present the distribution and kinematics of the molecular gas in the circumnuclear disk (CND, 400 pc x 200 pc) of Centaurus A with resolutions of ~5 pc (0.3 arcsec) and shed light onto the mechanism feeding the Active Galactic Nucleus (AGN) using CO(3-2), HCO+(4-3), HCN(4-3), and CO(6-5) observations obtained with ALMA. Multiple filaments or streamers of tens to a hundred parsec scale exist within the CND, which form a ring-like structure with an unprojected diameter of 9 x 6 arcsec (162pc x 108pc) and a position angle PA = 155deg. Inside the nuclear ring, there are two leading and straight filamentary structures with lengths of about 30-60pc at PA = 120deg on opposite sides of the AGN, with a rotational symmetry of 180deg and steeper position-velocity diagrams, which are interpreted as nuclear shocks due to non-circular motions. Along the filaments, and unlike other nearby AGNs, several dense molecular clumps present low HCN/HCO+(4-3) ratios (~0.5). The filaments abruptly end in the probed transitions at r = 20pc from the AGN, but previous near-IR H2 (J=1-0) S(1) maps show that they continue in an even ~1000 K), winding up in the form of nuclear spirals, and forming an inner ring structure with another set of symmetric filaments along the N-S direction and within r = 10pc. The molecular gas is governed primarily by non-circular motions, being the successive shock fronts at different scales where loss of angular momentum occurs, a mechanism which may feed efficiently powerful radio galaxies down to parsec scales.Comment: 46 pages. Accepted for publication in Ap

Searches for New Quarks and Leptons Produced in Z-Boson Decay

We have searched for events with new-particle topologies in 390 hadronic Z decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower limits of 40.7 GeV/c^2 for the top-quark mass, 42.0 GeV/c^2 for the mass of a fourth-generation charge - 1/3 quark, and 41.3 GeV/c^2 for the mass of an unstable Dirac neutral lepton