Putting mobile DNA to work: The toolbox

This chapter reviews some mobile DNA tools currently being used in DNA sequencing for manipulating clones efficiently, and in functional analysis of more modest segments of DNA containing one or a few genes as well as entire genomes. It covers the increasing use of transposons as genetic tags and as devices for the delivery and selective destruction of genes. It also provides a brief review of some recent applications of transposons as genetic markers. Two systems have recently been developed to attack the difficulties associated with the often complex subcloning steps required to ensure efficient recombinant protein expression. The original uses of transposons as tools for genome analysis date back to Casadaban's pioneering work with Mu in Escherichia coli . A variation on the footprinting theme for analyzing the genomes of naturally transformable bacteria referred to as genomic analysis and mapping through in vitro transposition (GAMBIT) has also been described. A most powerful technology based on Cre is the activation and shutoff of the target gene in transgenic animals. In recent years, several groups have used mariner/Tc1 elements to perform mutagenesis and to deliver genes to various organisms. The transposon has many attractive features, but its main shortcoming is that it is quite specific for TA dinucleotides in every species examined. This chapter focuses on the practical application of transposons as tangible tools for the manipulation of DNA sequences and of cellular phenotypes.