THE MU ELEMENTS OF ZEA-MAYS

This chapter focuses on the biology of the mutator (Mu) system in maize. The chapter discusses what is currently known about the structure and properties of the various Mu elements, including the transmission, timing, and maintenance and loss of mutator activity. Extensive genetic and molecular experiments have demonstrated that the increased mutation frequency is caused by a family of transposable elements referred to as Mu elements. The chapter also describes the structure and diversity of the Mu elements. The chapter discusses the process of methylation and the recent discovery and characterization of a Mu element that regulates the transposition of other Mu elements. Various studies that examine Mu element transposition are reviewed in the chapter, along with the discussion on the effects Mu elements on adjacent gene expression and the uses of Mu elements in mutagenesis and transposon tagging. The chapter distinguishes between active and inactive stocks based on whether the activity of the Mu elements is detectable by at least one of a number of different tests presented in the chapter. © 1992 Academic Press Inc.