An effective technique using an Escherichia coli plasmid system was developed to clone fragments of exogenous DNA of as large as 100 kilobase pairs. The characteristic features of this technique are the use of a low copy number (one to two) mini-F based plasmid vector and the introduction of artificial lambda cosR ends into the termini of DNA sources and then of the cosL ends into those of line...

The maintenance of a plasmid vector-host system that selects for bacteria carrying the plasmid without the need for antibiotics is described. In this system, the bacteriophage 434 repressor gene cloned on the plasmid protects the host from lysis by a lambda imm434 cI- prophage. Cells that occasionally lose the plasmid are killed by prophage induction and therefore do not accumulate in the growi...

The Lyme disease agent Borrelia burgdorferi maintains both linear and circular plasmids that appear to be essential for mammalian infection. Recent studies have characterized the circular plasmid regions that confer autonomous replication, but the genetic elements necessary for linear plasmid maintenance have not been experimentally identified. Two vectors derived from linear plasmids lp25 and ...

Abstract: Coxsackievirus B3 (CVB3) is the most common agent known to cause viral myocarditis. The viral genome encodes a single polyprotein that is cleaved to produce several proteins by virally encoded proteases. Most of this proteolytic processing is catalyzed by a cysteine protease called 3C. The 3C protease plays major role in viral replication and cellular damage. To understand the mecha...

Background: DNA damage is one of the major consequences of radiation exposure onto the biological systems. A series of compounds including flavanoids were found to render DNA protection against radiation damage. In this study we elucidated the potential of rutin and rutin hydrate to protect plasmid DNA against damage induced by irradiation. Materials and Methods: DPPH and hydroxyl radical scave...

A 4.2-kilobase (kb) cryptic plasmid is present in 96% of isolates of Neisseria gonorrhoeae. An inability to construct isogenic derivatives which vary in the presence of the 4.2-kb plasmid has prevented the study of its function. We report a method to deliver an intact 4.2-kb plasmid into plasmidless gonococcal strains. The method involved transformation with novel 15.7-kb hybrid penicillinase-p...

Fifty-four strains of Rhodococcus equi from different clinical sources (mainly horses and pigs) were examined for their plasmid content by two screening methods. Plasmids were detected in 49 of 54 strains. A plasmid of approximately 80 kb was isolated from 21 of 22 isolates from horses and 20 of 28 isolates from pigs, and a 105-kb plasmid was isolated from 7 of 28 isolates from pigs. The 80-kb ...

The efficient partitioning of the 2-microm plasmid of Saccharomyces cerevisiae at cell division is dependent on two plasmid-encoded proteins (Rep1p and Rep2p), together with the cis-acting locus REP3 (STB). In addition, host encoded factors are likely to contribute to plasmid segregation. Direct observation of a 2-microm-derived plasmid in live yeast cells indicates that the multiple plasmid co...

Objective(s): Polyethylenimine (PEI) is one of the most widely used polymers in gene delivery. The aim of this study was to modify PEI by replacing some of its primary amines with Brevinin 2R (BR-2R) peptide in order to increase the efficiency of gene delivery.Materials and Methods: Polyethylenimine was modified by BR-2R peptide by two d...