Building Civic Infrastructure: Implementing Community Partnership Grant Programmes in South Africa

This article examines recent efforts to establish Community Partnership Grant Programmes (CPG) in six South African communities. CPG programmes provide the financial and organizational infrastructure to support citizen-initiated neighbourhood projects

Probing the DNA sequence specificity of Escherichia coli RECA protein

Escherichia coli RecA protein catalyzes the central DNA strand-exchange step of homologous recombination, which is essential for the repair of double-stranded DNA breaks. In this reaction, RecA first polymerizes on single-stranded DNA (ssDNA) to form a right-handed helical filament with one monomer per 3 nt of ssDNA. RecA generally binds to any sequence of ssDNA but has a preference for GT-rich sequences, as found in the recombination hot spot Chi (5′-GCTGGTGG-3′). When this sequence is located within an oligonucleotide, binding of RecA is phased relative to it, with a periodicity of three nucleotides. This implies that there are three separate nucleotide-binding sites within a RecA monomer that may exhibit preferences for the four different nucleotides. Here we have used a RecA coprotease assay to further probe the ssDNA sequence specificity of E.coli RecA protein. The extent of self-cleavage of a λ repressor fragment in the presence of RecA, ADP-AlF(4) and 64 different trinucleotide-repeating 15mer oligonucleotides was determined. The coprotease activity of RecA is strongly dependent on the ssDNA sequence, with TGG-repeating sequences giving by far the highest coprotease activity, and GC and AT-rich sequences the lowest. For selected trinucleotide-repeating sequences, the DNA-dependent ATPase and DNA-binding activities of RecA were also determined. The DNA-binding and coprotease activities of RecA have the same sequence dependence, which is essentially opposite to that of the ATPase activity of RecA. The implications with regard to the biological mechanism of RecA are discussed

Crystallization of a Bacterial Single Stranded Annealing DNA Repair Protein

INTRODUCTION: Single-stranded annealing (SSA) proteins bind to single-stranded DNA (ssDNA) and promote the pairing of homologous DNA strands, a process that is involved in the repair of double-stranded breaks. This work focuses on RecT and β protein, from Escherichia coli and bacteriophage lambda, respectively, which are two classic examples of SSA proteins. The human protein Rad52 promotes the same reactions as RecT and β, and is involved in multiple DNA repair pathways. IMPORTANCE: Cells and DNA have mechanisms that repair mutations and failure to do so may lead to cancer. Chemotherapy requires study of repair mechanisms. Therefore, it is important to understand the DNA repair processes of RecT and β. Electron Microscopy studies propose that the proteins form oligomeric rings and helical filaments, but information on the fold of the proteins and the DNA binding sites on the surface of the oligomers is not available. This information can be obtained from high resolution images of a protein’s structure. AIM: The aim of this study is to determine the mechanism by which SSA proteins bind to ssDNA and promote the annealing of complimentary DNA strands. This will increase our general understanding of how proteins recognize and repair damaged sites of DNA in cells. Our approach will employ the powerful technique of x-ray crystallography to determine the three-dimensional structure of SSA proteins at high resolution. This technique requires that the SSA protein be crystallized. METHODS: A sample of RecT or β is purified and screened for initial crystals which are then optimized to grow larger crystals. Once large crystals form, x-ray diffraction is used to solve the three-dimensional atomic structure of the protein, preferably in complex with DNA substrates. CONCLUSION: The first large crystals of RecT that can diffract to 6-7 Angstroms have been formed in the lab, which is a significant step toward understanding the protein repair mechanism, which will ultimately provide a foundation for improved applications in cancer treatment

Comparing internal migration across the countries of Latin America: A multidimensional approach.

While considerable progress has been made in understanding the way particular aspects of internal migration, such as its intensity, age profile and spatial impact, vary between countries around the world, little attention to date has been given to establishing how these dimensions of migration interact in different national settings. We use recently developed measures of internal migration that are scale-independent to compare the overall intensity, age composition, spatial impact, and distance profile of internal migration in 19 Latin American countries. Comparisons reveal substantial cross-national variation but cluster analysis suggests the different dimensions of migration evolve systematically to form a broad sequence characterised by low intensities, young ages at migration, unbalanced flows and high friction of distance at lower levels of development, trending to high intensities, an older age profile of migration, more closely balanced flows and lower friction of distance at later stages of development. However, the transition is not linear and local contingencies, such as international migration and political control, often distort the migration-development nexus, leading to unique migration patterns in individual national contexts

Important Legal Matters in Retirement.

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A Mid-Infrared Study of the Young Stellar Population in the NGC 2024 Cluster

We present the results of the first broadband 10.8 um survey of the NGC 2024 cluster. The mid-infrared data were combined with our previously published JHKL photometry in order to construct spectral energy distributions for all detected sources. The main scientific goals were to investigate the nature of the young stellar objects (YSOs) in the cluster, and to examine the efficiency of detecting circumstellar disk sources from near-infrared JHKL color-color diagrams. Out of 59 sources surveyed having K-band magnitudes K < 10.5, we detected 35 (~59%) at 10 um. Combining these detections, and upper limits for the non-detections, with existing JHKL data, we identify 1 Class I, 6 flat spectrum, 28 Class II and 5 Class III sources. We find a circumstellar disk fraction for NGC 2024 of ~85% +/- 15%, which confirms earlier published suggestions that the majority, if not all, of the stars in NGC 2024 formed with disks, and these disks still exist at the present time. In addition, all but one of the disk sources identified in our survey lie in the infrared excess region of the JHKL color-color diagram for the cluster. This demonstrates that JHKL color-color diagrams are extremely efficient in identifying YSOs with disks. Of the 14 sources with K - L colors suggestive of protostellar objects, \~29% are protostellar in nature, while ~7% are true Class I YSOs. This may be due to extinction producing very red K - L colors in Class II YSOs, thus making them appear similar in color to protostars. This suggests caution must be applied when estimating the sizes and lifetimes of protostellar populations within star forming regions based on K - L colors alone. Finally, we calculate the luminosities of the Class II YSOs in NGC 2024, rho Oph and Taurus and discuss the results.Comment: 30 pages, 8 figures, paper to appear in March A

Infrared and Raman screening of seized novel psychoactive substances:a large scale study of >200 samples

The potential of IR absorption and Raman spectroscopy for rapid identification of novel psychoactive sub- stances (NPS) has been tested using a set of 221 unsorted seized samples suspected of containing NPS. Both IR and Raman spectra showed large variation between the different sub-classifications of NPS and smaller, but still distinguishable, differences between closely related compounds within the same class. In initial tests, screening the samples using spectral searching against a limited reference library allowed only 41% of the samples to be fully identified. The limiting factor in the identification was the large number of active compounds in the seized samples for which no reference vibrational data were available in the libraries rather than poor spectral quality. Therefore, when 33 of these compounds were independently identified by NMR and mass spectrometry and their spectra used to extend the libraries, the percentage of samples identified by IR and Raman screening alone increased to 76%, with only 7% of samples having no identifiable constituents. This study, which is the largest of its type ever carried out, therefore demon- strates that this approach of detecting non-matching samples and then identifying them using standard analytical methods has considerable potential in NPS screening since it allows rapid identification of the constituents of the majority of street quality samples. Only one complete feedback cycle was carried out in this study but there is clearly the potential to carry out continuous identification/updating when this system is used in operational settings

Nonlinear Outcome of Gravitational Instability in Cooling, Gaseous Disks

Thin, Keplerian accretion disks generically become gravitationally unstable at large radius. I investigate the nonlinear outcome of such instability in cool disks using razor-thin, local, numerical models. Cooling, characterized by a constant cooling time t_c, drives the instability. I show analytically that, if the disk can reach a steady state in which heating by dissipation of turbulence balances cooling, then the dimensionless angular momentum flux density \alpha = ((9/4) \gamma (\gamma-1) \Omega t_c)^{-1}. Numerical experiments show that: (1) if t_c \gtrsim 3\Omega^{-1} then the disk reaches a steady, gravito-turbulent state in which Q \sim 1 and cooling is balanced by heating due to dissipation of turbulence; (2) if t_c \lesssim 3\Omega^{-1}, then the disk fragments, possibly forming planets or stars; (3) in a steady, gravito-turbulent state, surface density structures have a characteristic physical scale \sim 64 G \Sigma/\Omega^2 that is independent of the size of the computational domain.Comment: 16 pages, 11 figures, aastex 5.0, to appear in Ap

Interpretation of Serologic Tests for Syphilis

Document outlining information about appropriate laboratory testing, test evaluation, and patient care for persons suspected of having syphilis

The Ursinus Weekly, October 14, 1963

Schwalm and Ball elected to UC Board of Directors • College Bowl qualification test to be given Tuesday in Pfahler • Sunday vespers programs begun • Race to be subject of Groth\u27s talk • Branden to lecture on philosophy of Ayn Rand • Curtain Club plans theatre in round production • Armstrong\u27s class to tour museum • Women seek votes for constitutional revision • 3rd annual Parents Day planned for October 19 • Activities planned by Outing Club • Banquet launches student teachers • Frosh, sophs moan: Et tu, John Adams • Winterthur visit set for Oct. 16-17 • Editorial: Campus renovations • Goldwater: I\u27d be damn mad • Greek gleanings • College, cars and confusion • Mushrooms to Shakespeare; Iceland to England • About the tax cut • Harpsichordist declared outstanding in Forum • Wall added to Spanish dept. • Weekly reporter interviews Eugene Carson Blake • Fall Y-retreat held a success • Johns Hopkins\u27 comeback deadlocks Ursinus, 15-15 • Player of the week: Tony Sermarini • Turnout brightens picture • Interview with Walt Kinderman • UC blanks hockey opponents • Hockey teams win two from Templehttps://digitalcommons.ursinus.edu/weekly/1253/thumbnail.jp