Taming the tiger by the tail: modulation of DNA damage responses by telomeres

Telomeres are by definition stable and inert chromosome ends, whereas internal chromosome breaks are potent stimulators of the DNA damage response (DDR). Telomeres do not, as might be expected, exclude DDR proteins from chromosome ends but instead engage with many DDR proteins. However, the most powerful DDRs, those that might induce chromosome fusion or cell-cycle arrest, are inhibited at telomeres. In budding yeast, many DDR proteins that accumulate most rapidly at double strand breaks (DSBs), have important functions in physiological telomere maintenance, whereas DDR proteins that arrive later tend to have less important functions. Considerable diversity in telomere structure has evolved in different organisms and, perhaps reflecting this diversity, different DDR proteins seem to have distinct roles in telomere physiology in different organisms. Drawing principally on studies in simple model organisms such as budding yeast, in which many fundamental aspects of the DDR and telomere biology have been established; current views on how telomeres harness aspects of DDR pathways to maintain telomere stability and permit cell-cycle division are discussed

High-frequency extensions of magnetorotational instability in astrophysical plasmas

High-frequency extensions of magnetorotational instability driven by the Velikhov effect beyond the standard magnetohydrodynamic (MHD) regime are studied. The existence of the well-known Hall regime and a new electron inertia regime is demonstrated. The electron inertia regime is realized for a lesser plasma magnetization of rotating plasma than that in the Hall regime. It includes the subregime of nonmagnetized electrons. It is shown that, in contrast to the standard MHD regime and the Hall regime, magnetorotational instability in this subregime can be driven only at positive values of dln Omega/dlnr, where Omega is the plasma rotation frequency and r is the radial coordinate. The permittivity of rotating plasma beyond the standard MHD regime, including both the Hall regime and the electron inertia regime, is calculated.Russian Foundation for Basic Research[06-02-16767]Russian Foundation for Basic ResearchRF Program for State Support of Leading Scientific Schools[9878.2006.2]RF Program for State Support of Leading Scientific SchoolsInternational Science and Technology CenterInternational Science and Technology Center[G-1217]Science and Technology Center in UkraineScience and Technology Center in Ukraine[3473]Research Foundation of the State of Sao Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Council of Scientific and Technological Development (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Ministry of Science and Technology of the Federative Republic of BrazilMinistry of Science and Technology of the Federative Republic of Brazi

U.S./Russian cooperative efforts to enhance nuclear MPC&A at VNIITF, (Chelyabinsk-70)

The All Russian Scientific Research Institute of Technical Physics (VNIITF) is one of the major sites in the nuclear weapons complex in Russia. The site contains a number of research facilities which use nuclear material as well as assembly, disassembly, and testing of prototypes (pilot samples) of nuclear weapons. VNIITF also has ties to the major nuclear materials production facilities in the Urals region of Russia. The objective of the U.S./Russian Materials Protection Control and Accounting (MPC&A) cooperative program between the US Department of Energy and Russia�s Ministry of Atomic Eneryy, at VNIITF is to improve the protection and accountability of nuclear material at VNIITF. Enhanced safeguards systems have been implemented at a reactor test area called the Pulse Research Reactor Facility (PRR) in Area 20. The area contains three pulse reactors with associated storage areas. The integrated MPC&A system at the PRR was demonstrated to US and Russian audiences in May, 1998. Expansion of work into several new facilities is underway both in Area 20 and at other locations. These include processing and production facilities some of which are considered sensitive facilities, by the Russian side. Methods have been developed to assure that work is done as agreed without actually having access to the buildings. C-70 has developed an extensive computerized system which integrates the physical security alarm station with elements of the nuclear material control system. Under the MPC&A program, the existing systems have been augmented with Russian and US technologies. This paper will describe the work completed at the PRR, and the on-going activities and cooperative effort between the Lawrence Livermore, Los Alamos, Sandia, Oak Ridge, Pacific Northwest, and Brookhaven US Department of Energy National Laboratories in support of VNIITF