Meiosis chromosome behavior

All of these methods identify mutations that disturb the formation of spores severely, showing defects in either entry into meiosis, meiotic chromosome behavior, or spore morphogenesis (and, for the ether test, germination). As with any good mutant hunt, secondary screens to identify mutants specifically defective in a particular aspect of meiosis must be established. For instance, ether sensitivity could reflect spore inviability due to chromosome missegregation or could be due to defects in spore wall assembly. Direct spore dissection of candidate mutants can distinguish between these two possibilities. 

Although classic mutant hunts are likely to detect important genes required for meiosis, a subset of genes may fail to be detected due to redundancy of function. Recent advances in molecular genetic approaches should enable researchers to identify a complete sets of genes required for meiotic chromosome behavior. 

Much has been learned about Drosophila meiosis by immunocytochemical studies of whole-mount oocytes lacking functional meiotic proteins and by localization of some of the relevant proteins (McKim et al. 1993 White-Cooper et al. 1993 Afshar et al. 1995 Endow and Komma 1996 Matthies et al. 1996 Moore et al. 1998). However, none of these classic methods easily point out kinetic problems, nor are the earliest points of deviation always readily obvious by static methods. For these reasons, and because the behavior of the highly dynamic components of the meiotic spindle may be perturbed in meiotic mutants, methods have been developed to directly observe the cytoskeleton and chromosomes in living egg chambers (Theurkauf 1994a Endow and Komma 1996 Matthies et al. 1996). 

---