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4 Mutation

Robert C. Johnsen, David L. Baillie


Mutations are tools that can be used to study the organization and function of the elements of a genome. Small random alterations in the DNA sequence can provide clues to the number of functional sequences in the genome, the mutability of the various sequences, and the functions of the various sequences. The study of DNA rearrangements such as translocations, duplications, deficiencies, and inversions can lead to an understanding of how homologs recognize each other and how they pair, re-combine, and segregate (see Albertson et al., this volume). A sequenced genome may allow for the identification of all the proteins in the organism, but this does not provide sufficient information to identify the pathways and structures in which those proteins function. To take full advantage of the sequence information, it is necessary to integrate it with the cellular and developmental biology of the organism. This integration requires functional analysis of as many genes as possible, and this is most easily accomplished by mutation. Methods for generating mutations in Caenorhabditis elegans have been reviewed recently (Anderson 1995). In this chapter, we discuss the analysis of mutations.

The three types of mutagenesis are target-selected, spontaneous, and induced; the latter two are nonspecific. Target-selected mutagenesis is a powerful tool for generating mutations in any selected sequence (Plasterk and van Luenen, this volume). A sequence is generally selected because it is known to have some function. The sequence may be a known gene, it may have matches in existing databases, or it may...

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