the production of experimentally induced drug resistance in the laboratory provides valuable opportunities for investigators to study the nature and genetics of drug resistance mechanisms to a given agent, patterns of cross resistance and the mode of action of drugs. at the beginning the continuous drug exposure was chosen as a standard procedure to produce drug— resistant strains of p. falcipa...

Plasmids that contain synthetic genes coding for small oligoribonucleotides called external guide sequences (EGSs) have been introduced into strains of Escherichia coli harboring antibiotic resistance genes. The EGSs direct RNase P to cleave the mRNAs transcribed from these genes thereby converting the phenotype of drug-resistant cells to drug sensitivity. Increasing the EGS-to-target mRNA rati...