Poliovirus mutant that contains a cold-sensitive defect in viral RNA synthesis

By manipulating an infectious cDNA clone of poliovirus, we have introduced a single-codon insertion into the 3A region of the viral genome which has been proposed to encode a functional precursor of the virion-linked protein VPg. The resulting mutant was cold sensitive in monkey kidney cells. Viral RNA synthesis was poor at 32.5 degrees C, although no other function of the virus was obviously affected. The synthesis of both positive and negative strands was severely depressed. Temperature shift experiments suggest that a normal level of production of the affected function was required only during the early (exponential) phase of RNA synthesis. Analysis of viral polyprotein processing at the nonpermissive temperature revealed that some of the normal cleavages were not made, most likely as a consequence of the defect in RNA synthesis or as a result of the concomitant reduction in the level of virally encoded proteases

Level structures on the Weierstrass family of cubics

Let W -> A^2 be the universal Weierstrass family of cubic curves over C. For each N >= 2, we construct surfaces parametrizing the three standard kinds of level N structures on the smooth fibers of W. We then complete these surfaces to finite covers of A^2. Since W -> A^2 is the versal deformation space of a cusp singularity, these surfaces convey information about the level structure on any family of curves of genus g degenerating to a cuspidal curve. Our goal in this note is to determine for which values of N these surfaces are smooth over (0,0). From a topological perspective, the results determine the homeomorphism type of certain branched covers of S^3 with monodromy in SL_2(Z/N).Comment: LaTeX, 12 pages; added section giving a topological interpretation of the result

Chaperone OsmY facilitates the biogenesis of a major family of autotransporters

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152790/1/mmi14358.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152790/2/mmi14358_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152790/3/mmi14358-sup-0001-Supinfo.pd

Conserved tertiary base pairing ensures proper RNA folding and efficient assembly of the signal recognition particle Alu domain

Proper folding of the RNA is an essential step in the assembly of functional ribonucleoprotein complexes. We examined the role of conserved base pairs formed between two distant loops in the Alu portion of the mammalian signal recognition particle RNA (SRP RNA) in SRP assembly and functions. Mutations disrupting base pairing interfere with folding of the Alu portion of the SRP RNA as monitored by probing the RNA structure and the binding of the protein SRP9/14. Complementary mutations rescue the defect establishing a role of the tertiary loop-loop interaction in RNA folding. The same mutations in the Alu domain have no major effect on binding of proteins to the S domain suggesting that the S domain can fold independently. Once assembled into a complete SRP, even particles that contain mutant RNA are active in arresting nascent chain elongation and translocation into microsomes, and, therefore, tertiary base pairing does not appear to be essential for these activities. Our results suggest a model in which the loop-loop interaction and binding of the protein SRP9/14 play an important role in the early steps of SRP RNA folding and assembl

Education Can Compensate for Society - a Bit

In this paper I reflect on the findings of a number of loosely related research projects undertaken with colleagues over the last ten years. Their common theme is equity, in formal education and beyond, in wider family and social settings, and with inequity expressed as the stratification of a variety of educational outcomes. The projects are based on a standard mixture of pre-existing records, official documents, large-scale surveys, observations, interviews and focus groups. The numeric data were largely used to create biographical models of educational experiences, and the in-depth data were used to try to explain individual decisions and disparities at each stage of the model. Data have been collected for England and Wales, in five other countries of the European Union and for Japan. A meta-view of these various findings suggests that national school intakes tend to be at least moderately segregated by prior attainment and socio-economic factors, and that learning outcomes as assessed by formal means, such as examinations, are heavily stratified by these same factors. There is no convincing evidence that compulsory schooling does very much to overcome the initial disparity in the resources and attainment of school intakes. On the other hand, there are indications that the nature of a national school system and the social experiences of young people in schools can begin to equalise educational outcomes as more widely envisaged, including learning to trust and willingness to help others, aspirations, and attitudes to continuing in education and training. The cost-free implications of the argument in this paper, if accepted, are that everything possible should be done to make school intakes comprehensive, and that explicit consideration, by teachers and leaders, of the applied principles of equity could reduce potentially harmful misunderstandings in educational contexts

The nil Hecke ring and singularity of Schubert varieties

We give a criterion for smoothness of a point in any Schubert variety in any G/B in terms of the nil Hecke ring.Comment: AMSTE

New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration

We report on the extraction of the structure functions F_2 and Delta xF_3 = xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross sections. The extraction is performed in a physics model independent (PMI) way. This first measurement for Delta xF_3, which is useful in testing models of heavy charm production, is higher than current theoretical predictions. The F_2 (PMI) values measured in neutrino and muon scattering are in good agreement with the predictions of Next to Leading Order PDFs (using massive charm production schemes), thus resolving the long-standing discrepancy between the two sets of data.Comment: 5 pages. Presented by Arie Bodek at the CIPNAP2000 Conference, Quebec City, May 200

A Search for Muon-neutrino to Electron-neutrino and Muon-antineutrino to Electron-antineutrino Oscillations at NuTeV

Limits on $\nu_\mu \to \nu_e$ and $\bar\nu_\mu \to \bar\nu_e$ oscillations are extracted using the NuTeV detector with sign-selected $\nu_\mu$ and \nub_\mu beams. In \nub_\mu mode, for the case of $\sin^2 2\alpha = 1$, $\Delta m^2 > 2.6$ ${\rm eV^2}$ is excluded, and for $\Delta m^2 \gg 1000$ ${\rm eV^2}$, $\sin^2 2\alpha > 1.1 \times 10^{-3}$. The NuTeV data exclude the high $\Delta m^2$ end of $\bar\nu_\mu \to \bar\nu_e$ oscillations parameters favored by the LSND experiment without the need to assume that the oscillation parameters for $\nu$ and \nub are the same. We present the most stringent experimental limits for $\nu_\mu (\bar{\nu}_\mu) \to \nu_e (\bar{\nu}_e)$ oscillations in the large $\Delta m^2$ region.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. Letters, UR-164

Observation of an Anomalous Number of Dimuon Events in a High Energy Neutrino Beam

A search for long-lived neutral particles (N^0's) with masses above 2.2 GeV/c^2 that decay into at least one muon has been performed using an instrumented decay channel at the NuTeV experiment at Fermilab. Data were examined for particles decaying into the final states mu mu, mu e, and mu pi. Three mu mu events were observed over an expected Standard Model background of 0.069 +/- 0.010 events; no events were observed in the other modes.Comment: 5 pages, 3 figures, Submitted to Phys. Rev. Let