WHAT RESTRICTS THE ACTIVITY OF MARINER-LIKE TRANSPOSABLE ELEMENTS

A number of mechanisms have recently been described that might be impo rtant in restricting the level of activity of mariner-like transposabl e elements (MLEs) in natural populations. These mechanisms include ove rproduction inhibition, in which increasing the dose of transposase de creases net activity. Another mechanism is mediated by certain missens e mutations, in which a mutant transposase protein impairs the activit y of the wild-type transposase in heterozygous mutant/nonmutant genoty pes. A further mechanism is the potential for transposase titration by defective elements that retain transposase binding activity. The issu e of regulation is not only of theoretical importance in understanding the molecular and evolutionary genetics of MLEs, but also of practica l significance in learning how best to use MLEs in the germline transf ormation of insect pests and disease vectors.