We present a detailed study of the extrusion of an imperfect palindrome, derived from the terminal regions of vaccinia virus DNA and contained in a superhelical plasmid, into a cruciform containing bulged bases. We monitor the course of extrusion by two-dimensional gel electrophoresis experiments as a function of temperature and linking number. We find that extrusion pauses at partially extrude...

In this paper, a cruciform coupler with half mode substrate integrated waveguide structure is presented. The prototype coupler consists of four half mode SIW structures crossing each other in right angle and two metallic posts are inserted in free section of junction in order to reach the coupling properties. Compact size and broadband operation are the features of this coupler. The size of cou...

It is shown that an orientation anisotropy exists for the magnitude of induced brightness in a cruciform stimulus consisting of a grey test patch positioned at the intersection of two inducing bars, one black and one white, oriented at right angles to each other. When the cruciform was oriented such that the white bar was horizontal, the grey patch appeared darker than when the same cruciform w...

We have analyzed the effect of base composition at the center of symmetry of inverted repeated DNA sequences on cruciform transitions in supercoiled DNA. For this we have constructed two series of palindromic DNA sequences: one set with differing center and one set with differing center and arm sequences. The F series consists of two 96-base pair perfect inverted repeats which are identical exc...

The binding of chromosomal protein HMG1 to a palindromic sequence that can form the cruciform structure in supercoiled DNA and the subsequent effect on the transcription of the sequence were examined with pBR322 and its derivative plasmids. The plasmid DNA under negative supercoiling showed a selective sensitivity to nuclease S1. HMG1 protected against the nuclease S1 digestion. The results of ...

An endonuclease specific for cruciform junctions has been purified from yeast cells treated with a DNA-damaging agent. The activity was followed through five chromatographic steps by assaying for the linearization of supercoiled plasmid DNA, which extrudes cruciform structures in vitro. The sites of cleavage on pColIR215 were sequenced, and nicks were located to positions symmetrically opposed ...

A DNA molecule under negative superhelical stress becomes susceptible to transitions to alternate structures. The accessible alternate conformations depend on base sequence and compete for occupancy. We have developed a method to calculate equilibrium distributions among the states available to such systems, as well as their average thermodynamic properties. Here we extend this approach to incl...

Although the Cold War has been over for a decade, conditions remain that are producing new instabilities—and potential conflicts—in the rapidly changing contemporary world. Missile proliferation issue is a case in point. Missiles, as the most effective delivery vehicles, have the advantages of high velocity, low cost, and great accuracy in a conflict. Few current control or defense measures are...