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Post-meiotic segregation of alleles, which is seen, for example, in the 5:3 distribution of alleles in the products of a single meiosis in fungi, has been thought to be due to the non-repair of heteroduplex regions formed during genetic recombination. In current models of genetic recombination, heteroduplex DNA is formed either as the primary intermediate(More)
PURPOSE Previous studies have demonstrated that some organophosphorus pesticides (OPs) move from application sites to non-target crops. The purpose of this study was to determine if aerial movement and deposition of three organophosphate insecticides (chlorpyrifos, diazinon and parathion or their oxygen analogs) occur on non-target crops as a result of(More)
A number of DNA viruses carry apoptosis-inhibiting genes which enable the virus to escape from the host response. The adenovirus E1B 19K protein can inhibit apoptosis induced by E1A, tumour-necrosis factor-alpha, FAS antigen and nerve growth factor deprivation. The molecular basis of this inhibition remains poorly understood, but the fact that protection is(More)
DNA in the cell is intertwined at several levels: one polynucleotide strand wraps helically around its complement and the double helix is in turn coiled in space. The higher-order intertwining most often takes the form of supercoiling of the helix axis, but can also be observed as the wrapping of one DNA duplex around another, as in catenation. We have(More)
The geometric properties of duplex DNA are systematically altered when the DNA is wrapped on a protein surface. The linking number of surface-wrapped closed circular DNA is the sum of two integers: the winding number, phi, a function of the helical repeat; and the surface linking number, SLk, a newly defined geometric constant that accounts for the effects(More)
It is well known that a large linking number induces an abrupt writhing of a circular rod with zero intrinsic curvature, i.e., the stress-free state of the rod is straight. We show here that for any rod with a uniform natural curvature, no matter how small the intrinsic curvature is, a twist will induce a continuous writhing from the circular configuration(More)
Closed DNA loops that contain intrinsic curvature occur in biologically important structures that are formed by bringing together proteins attached at distinct sites. Such loops constitute topological domains that are characterized by a linking number Delta Lk. We calculate, using finite-element analysis, the structural changes induced by small changes in(More)