The advantages of drosophila for mutation studies

Abstract

Summary The advantages Drosophila has to offer for studies on the induction of mutations and chromosome aberrations are in anifold. The wealth of specific tester strains, special markers, useful inversions, or other rearrangements makes it possible to test in one and the same experiment for the total spectrum of genetic changes ranging from dominant lethals and chromosome loss (as indication for non-restituted breaks) to translocations (misrepaired breaks), recessive lethals, deletions, crossing-over, nondisjunction, complete and mosaic visible mutations in a whole array of different germ cell stages. Moreover, a detailed genetic analysis of each of these is possible and thus may shed light on mechanisms and consequences of induction of the genetic changes involved. Studies on the ability of agents to produce both gene mutations and chromosome aberrations are particularly important when evaluating the relevance of current testing procedures for environmental mutagens in mammalian systems that are based on chromosome reakage effects. Thus, hycanthone, diethyl nitrosamine and diethyl sulphate that all produce recessive sex-linked lethals at high frequency in Drosophila, but no chromosome breakage, would erroneously register as safe in most mammalian test systems. New methods for the detection of autosomal non-disjunction have recently been worked out, and deficiencies which are expected to arise with a much higher frequency after chemical treatment than with X-rays, can be easily discovered by employing simple recessive lethal tests. One piece of recent evidence that strengthens the premise of the suitability of Drosophila for studies in chemical mutagenesis, is that in tests of “indirect mutagens” the flies appear to carry out the same activating transformations as those occurring in the mammalian liver. Furthermore, exact methods for chemical dosimetry are available. In addition to all other advantages, Drosophila certainly offers the quickest test system for mutations available in animals today. Consequently, it may provide guidance on the kind of questions that should be looked for in more laborious systems. Thus, observations on modifications and specificities in Drosophila, show at least that a particular treatment can be modified, and this may then be followed up in mammalian cells.