The Semidwarfs - A New Era in Rice Production.

52 p

The Telomere Binding Protein TRF2 Induces Chromatin Compaction

Mammalian telomeres are specialized chromatin structures that require the telomere binding protein, TRF2, for maintaining chromosome stability. In addition to its ability to modulate DNA repair activities, TRF2 also has direct effects on DNA structure and topology. Given that mammalian telomeric chromatin includes nucleosomes, we investigated the effect of this protein on chromatin structure. TRF2 bound to reconstituted telomeric nucleosomal fibers through both its basic N-terminus and its C-terminal DNA binding domain. Analytical agarose gel electrophoresis (AAGE) studies showed that TRF2 promoted the folding of nucleosomal arrays into more compact structures by neutralizing negative surface charge. A construct containing the N-terminal and TRFH domains together altered the charge and radius of nucleosomal arrays similarly to full-length TRF2 suggesting that TRF2-driven changes in global chromatin structure were largely due to these regions. However, the most compact chromatin structures were induced by the isolated basic N-terminal region, as judged by both AAGE and atomic force microscopy. Although the N-terminal region condensed nucleosomal array fibers, the TRFH domain, known to alter DNA topology, was required for stimulation of a strand invasion-like reaction with nucleosomal arrays. Optimal strand invasion also required the C-terminal DNA binding domain. Furthermore, the reaction was not stimulated on linear histone-free DNA. Our data suggest that nucleosomal chromatin has the ability to facilitate this activity of TRF2 which is thought to be involved in stabilizing looped telomere structures

Urban Governance Structure and Wage Disparities across US Metropolitan Areas

This paper analyses the determinants of spatial wage disparities in the US context for the period 1980-2000. Agglomeration benefits are estimated based on city productivity premia which are computed after controlling for the skills distribution among metropolitan areas as well as industry fixed effects. The drivers of productivity differentials that are taken into consideration are the size of the local economy, the spatial interactions among local autonomous economic systems and the structure of urban governance as well as the policy responses to the fragmentation issue. A metropolitan area with ten percentage more administrative units than another of the same size, experiences wages that are between 2.0% and 3.0% lower. The presence of a voluntary governance body is found to mitigate the problem of fragmentation only marginally, while the existence of special purpose districts have a negative impact on regional productivity. The implementation of a metropolitan government with a regional tax system is expected to increase productivity by around 6%

Synapsis of DNA ends by DNA-dependent protein kinase

The catalytic subunit of DNA-dependent protein kinase (DNA-PK(CS)) is required for a non-homologous end-joining pathway that repairs DNA double-strand breaks produced by ionizing radiation or V(D)J recombination; however, its role in this pathway has remained obscure. Using a neutravidin pull-down assay, we found that DNA-PK(CS) mediates formation of a synaptic complex containing two DNA molecules. Furthermore, kinase activity was cooperative with respect to DNA concentration, suggesting that activation of the kinase occurs only after DNA synapsis. Electron microscopy revealed complexes of two DNA ends brought together by two DNA-PK(CS) molecules. Our results suggest that DNA-PK(CS) brings DNA ends together and then undergoes activation of its kinase, presumably to regulate subsequent steps for processing and ligation of the ends

Design of a proposed hydro-electric development on the Desplaines River at Dresden Heights, Ill.

http://www.archive.org/details/designofproposed00curtB.S. in Civil Engineerin